4435 lines
110 KiB
C
4435 lines
110 KiB
C
/*
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* linux/fs/namei.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* Some corrections by tytso.
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*/
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/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
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* lookup logic.
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*/
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/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
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*/
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/pagemap.h>
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#include <linux/fsnotify.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/ima.h>
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/fcntl.h>
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#include <linux/device_cgroup.h>
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#include <linux/fs_struct.h>
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#include <linux/posix_acl.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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#include "mount.h"
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/* [Feb-1997 T. Schoebel-Theuer]
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* Fundamental changes in the pathname lookup mechanisms (namei)
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* were necessary because of omirr. The reason is that omirr needs
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* to know the _real_ pathname, not the user-supplied one, in case
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* of symlinks (and also when transname replacements occur).
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*
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* The new code replaces the old recursive symlink resolution with
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* an iterative one (in case of non-nested symlink chains). It does
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* this with calls to <fs>_follow_link().
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* As a side effect, dir_namei(), _namei() and follow_link() are now
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* replaced with a single function lookup_dentry() that can handle all
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* the special cases of the former code.
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*
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* With the new dcache, the pathname is stored at each inode, at least as
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* long as the refcount of the inode is positive. As a side effect, the
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* size of the dcache depends on the inode cache and thus is dynamic.
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*
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* [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
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* resolution to correspond with current state of the code.
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*
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* Note that the symlink resolution is not *completely* iterative.
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* There is still a significant amount of tail- and mid- recursion in
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* the algorithm. Also, note that <fs>_readlink() is not used in
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* lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
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* may return different results than <fs>_follow_link(). Many virtual
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* filesystems (including /proc) exhibit this behavior.
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*/
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/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
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* New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
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* and the name already exists in form of a symlink, try to create the new
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* name indicated by the symlink. The old code always complained that the
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* name already exists, due to not following the symlink even if its target
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* is nonexistent. The new semantics affects also mknod() and link() when
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* the name is a symlink pointing to a non-existent name.
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*
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* I don't know which semantics is the right one, since I have no access
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* to standards. But I found by trial that HP-UX 9.0 has the full "new"
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* semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
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* "old" one. Personally, I think the new semantics is much more logical.
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* Note that "ln old new" where "new" is a symlink pointing to a non-existing
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* file does succeed in both HP-UX and SunOs, but not in Solaris
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* and in the old Linux semantics.
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*/
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/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
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* semantics. See the comments in "open_namei" and "do_link" below.
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*
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* [10-Sep-98 Alan Modra] Another symlink change.
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*/
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/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
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* inside the path - always follow.
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* in the last component in creation/removal/renaming - never follow.
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* if LOOKUP_FOLLOW passed - follow.
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* if the pathname has trailing slashes - follow.
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* otherwise - don't follow.
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* (applied in that order).
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*
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* [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
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* restored for 2.4. This is the last surviving part of old 4.2BSD bug.
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* During the 2.4 we need to fix the userland stuff depending on it -
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* hopefully we will be able to get rid of that wart in 2.5. So far only
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* XEmacs seems to be relying on it...
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*/
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/*
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* [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
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* implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
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* any extra contention...
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*/
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/* In order to reduce some races, while at the same time doing additional
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* checking and hopefully speeding things up, we copy filenames to the
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* kernel data space before using them..
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*
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* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
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* PATH_MAX includes the nul terminator --RR.
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*/
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void final_putname(struct filename *name)
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{
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if (name->separate) {
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__putname(name->name);
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kfree(name);
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} else {
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__putname(name);
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}
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}
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#define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename))
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static struct filename *
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getname_flags(const char __user *filename, int flags, int *empty)
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{
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struct filename *result, *err;
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int len;
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long max;
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char *kname;
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result = audit_reusename(filename);
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if (result)
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return result;
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result = __getname();
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if (unlikely(!result))
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return ERR_PTR(-ENOMEM);
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/*
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* First, try to embed the struct filename inside the names_cache
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* allocation
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*/
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kname = (char *)result + sizeof(*result);
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result->name = kname;
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result->separate = false;
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max = EMBEDDED_NAME_MAX;
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recopy:
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len = strncpy_from_user(kname, filename, max);
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if (unlikely(len < 0)) {
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err = ERR_PTR(len);
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goto error;
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}
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/*
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* Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
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* separate struct filename so we can dedicate the entire
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* names_cache allocation for the pathname, and re-do the copy from
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* userland.
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*/
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if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) {
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kname = (char *)result;
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result = kzalloc(sizeof(*result), GFP_KERNEL);
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if (!result) {
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err = ERR_PTR(-ENOMEM);
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result = (struct filename *)kname;
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goto error;
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}
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result->name = kname;
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result->separate = true;
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max = PATH_MAX;
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goto recopy;
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}
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/* The empty path is special. */
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if (unlikely(!len)) {
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if (empty)
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*empty = 1;
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err = ERR_PTR(-ENOENT);
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if (!(flags & LOOKUP_EMPTY))
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goto error;
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}
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err = ERR_PTR(-ENAMETOOLONG);
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if (unlikely(len >= PATH_MAX))
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goto error;
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result->uptr = filename;
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audit_getname(result);
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return result;
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error:
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final_putname(result);
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return err;
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}
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struct filename *
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getname(const char __user * filename)
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{
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return getname_flags(filename, 0, NULL);
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}
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EXPORT_SYMBOL(getname);
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#ifdef CONFIG_AUDITSYSCALL
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void putname(struct filename *name)
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{
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if (unlikely(!audit_dummy_context()))
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return audit_putname(name);
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final_putname(name);
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}
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#endif
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static int check_acl(struct inode *inode, int mask)
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{
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#ifdef CONFIG_FS_POSIX_ACL
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struct posix_acl *acl;
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if (mask & MAY_NOT_BLOCK) {
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acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
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if (!acl)
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return -EAGAIN;
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/* no ->get_acl() calls in RCU mode... */
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if (acl == ACL_NOT_CACHED)
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return -ECHILD;
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return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
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}
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acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
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/*
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* A filesystem can force a ACL callback by just never filling the
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* ACL cache. But normally you'd fill the cache either at inode
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* instantiation time, or on the first ->get_acl call.
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*
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* If the filesystem doesn't have a get_acl() function at all, we'll
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* just create the negative cache entry.
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*/
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if (acl == ACL_NOT_CACHED) {
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if (inode->i_op->get_acl) {
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acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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} else {
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set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
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return -EAGAIN;
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}
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}
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if (acl) {
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int error = posix_acl_permission(inode, acl, mask);
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posix_acl_release(acl);
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return error;
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}
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#endif
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return -EAGAIN;
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}
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/*
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* This does the basic permission checking
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*/
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static int acl_permission_check(struct inode *inode, int mask)
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{
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unsigned int mode = inode->i_mode;
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if (likely(uid_eq(current_fsuid(), inode->i_uid)))
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mode >>= 6;
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else {
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if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
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int error = check_acl(inode, mask);
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if (error != -EAGAIN)
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return error;
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}
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if (in_group_p(inode->i_gid))
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mode >>= 3;
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}
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/*
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* If the DACs are ok we don't need any capability check.
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*/
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if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
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return 0;
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return -EACCES;
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}
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/**
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* generic_permission - check for access rights on a Posix-like filesystem
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* @inode: inode to check access rights for
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
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*
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* Used to check for read/write/execute permissions on a file.
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* We use "fsuid" for this, letting us set arbitrary permissions
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* for filesystem access without changing the "normal" uids which
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* are used for other things.
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*
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* generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
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* request cannot be satisfied (eg. requires blocking or too much complexity).
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* It would then be called again in ref-walk mode.
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*/
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int generic_permission(struct inode *inode, int mask)
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{
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int ret;
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/*
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* Do the basic permission checks.
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*/
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ret = acl_permission_check(inode, mask);
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if (ret != -EACCES)
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return ret;
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if (S_ISDIR(inode->i_mode)) {
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/* DACs are overridable for directories */
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if (inode_capable(inode, CAP_DAC_OVERRIDE))
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return 0;
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if (!(mask & MAY_WRITE))
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if (inode_capable(inode, CAP_DAC_READ_SEARCH))
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return 0;
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return -EACCES;
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}
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/*
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* Read/write DACs are always overridable.
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* Executable DACs are overridable when there is
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* at least one exec bit set.
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*/
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if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
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if (inode_capable(inode, CAP_DAC_OVERRIDE))
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return 0;
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/*
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* Searching includes executable on directories, else just read.
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*/
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mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
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if (mask == MAY_READ)
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if (inode_capable(inode, CAP_DAC_READ_SEARCH))
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return 0;
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return -EACCES;
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}
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/*
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* We _really_ want to just do "generic_permission()" without
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* even looking at the inode->i_op values. So we keep a cache
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* flag in inode->i_opflags, that says "this has not special
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* permission function, use the fast case".
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*/
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static inline int do_inode_permission(struct inode *inode, int mask)
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{
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if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
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if (likely(inode->i_op->permission))
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return inode->i_op->permission(inode, mask);
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/* This gets set once for the inode lifetime */
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spin_lock(&inode->i_lock);
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inode->i_opflags |= IOP_FASTPERM;
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spin_unlock(&inode->i_lock);
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}
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return generic_permission(inode, mask);
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}
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/**
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* __inode_permission - Check for access rights to a given inode
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* @inode: Inode to check permission on
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* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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*
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* Check for read/write/execute permissions on an inode.
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*
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* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
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*
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* This does not check for a read-only file system. You probably want
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* inode_permission().
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*/
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int __inode_permission(struct inode *inode, int mask)
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{
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int retval;
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if (unlikely(mask & MAY_WRITE)) {
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/*
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* Nobody gets write access to an immutable file.
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*/
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if (IS_IMMUTABLE(inode))
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return -EACCES;
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}
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retval = do_inode_permission(inode, mask);
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if (retval)
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return retval;
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retval = devcgroup_inode_permission(inode, mask);
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if (retval)
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return retval;
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return security_inode_permission(inode, mask);
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}
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|
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/**
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* sb_permission - Check superblock-level permissions
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* @sb: Superblock of inode to check permission on
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* @inode: Inode to check permission on
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* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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*
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* Separate out file-system wide checks from inode-specific permission checks.
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*/
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static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
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{
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if (unlikely(mask & MAY_WRITE)) {
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umode_t mode = inode->i_mode;
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|
|
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/* Nobody gets write access to a read-only fs. */
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if ((sb->s_flags & MS_RDONLY) &&
|
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(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
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return -EROFS;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* inode_permission - Check for access rights to a given inode
|
|
* @inode: Inode to check permission on
|
|
* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
|
|
*
|
|
* Check for read/write/execute permissions on an inode. We use fs[ug]id for
|
|
* this, letting us set arbitrary permissions for filesystem access without
|
|
* changing the "normal" UIDs which are used for other things.
|
|
*
|
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* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
|
|
*/
|
|
int inode_permission(struct inode *inode, int mask)
|
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{
|
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int retval;
|
|
|
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retval = sb_permission(inode->i_sb, inode, mask);
|
|
if (retval)
|
|
return retval;
|
|
return __inode_permission(inode, mask);
|
|
}
|
|
|
|
/**
|
|
* path_get - get a reference to a path
|
|
* @path: path to get the reference to
|
|
*
|
|
* Given a path increment the reference count to the dentry and the vfsmount.
|
|
*/
|
|
void path_get(const struct path *path)
|
|
{
|
|
mntget(path->mnt);
|
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dget(path->dentry);
|
|
}
|
|
EXPORT_SYMBOL(path_get);
|
|
|
|
/**
|
|
* path_put - put a reference to a path
|
|
* @path: path to put the reference to
|
|
*
|
|
* Given a path decrement the reference count to the dentry and the vfsmount.
|
|
*/
|
|
void path_put(const struct path *path)
|
|
{
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
}
|
|
EXPORT_SYMBOL(path_put);
|
|
|
|
/*
|
|
* Path walking has 2 modes, rcu-walk and ref-walk (see
|
|
* Documentation/filesystems/path-lookup.txt). In situations when we can't
|
|
* continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
|
|
* normal reference counts on dentries and vfsmounts to transition to rcu-walk
|
|
* mode. Refcounts are grabbed at the last known good point before rcu-walk
|
|
* got stuck, so ref-walk may continue from there. If this is not successful
|
|
* (eg. a seqcount has changed), then failure is returned and it's up to caller
|
|
* to restart the path walk from the beginning in ref-walk mode.
|
|
*/
|
|
|
|
/**
|
|
* unlazy_walk - try to switch to ref-walk mode.
|
|
* @nd: nameidata pathwalk data
|
|
* @dentry: child of nd->path.dentry or NULL
|
|
* Returns: 0 on success, -ECHILD on failure
|
|
*
|
|
* unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
|
|
* for ref-walk mode. @dentry must be a path found by a do_lookup call on
|
|
* @nd or NULL. Must be called from rcu-walk context.
|
|
*/
|
|
static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
struct dentry *parent = nd->path.dentry;
|
|
|
|
BUG_ON(!(nd->flags & LOOKUP_RCU));
|
|
|
|
/*
|
|
* After legitimizing the bastards, terminate_walk()
|
|
* will do the right thing for non-RCU mode, and all our
|
|
* subsequent exit cases should rcu_read_unlock()
|
|
* before returning. Do vfsmount first; if dentry
|
|
* can't be legitimized, just set nd->path.dentry to NULL
|
|
* and rely on dput(NULL) being a no-op.
|
|
*/
|
|
if (!legitimize_mnt(nd->path.mnt, nd->m_seq))
|
|
return -ECHILD;
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
|
|
if (!lockref_get_not_dead(&parent->d_lockref)) {
|
|
nd->path.dentry = NULL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* For a negative lookup, the lookup sequence point is the parents
|
|
* sequence point, and it only needs to revalidate the parent dentry.
|
|
*
|
|
* For a positive lookup, we need to move both the parent and the
|
|
* dentry from the RCU domain to be properly refcounted. And the
|
|
* sequence number in the dentry validates *both* dentry counters,
|
|
* since we checked the sequence number of the parent after we got
|
|
* the child sequence number. So we know the parent must still
|
|
* be valid if the child sequence number is still valid.
|
|
*/
|
|
if (!dentry) {
|
|
if (read_seqcount_retry(&parent->d_seq, nd->seq))
|
|
goto out;
|
|
BUG_ON(nd->inode != parent->d_inode);
|
|
} else {
|
|
if (!lockref_get_not_dead(&dentry->d_lockref))
|
|
goto out;
|
|
if (read_seqcount_retry(&dentry->d_seq, nd->seq))
|
|
goto drop_dentry;
|
|
}
|
|
|
|
/*
|
|
* Sequence counts matched. Now make sure that the root is
|
|
* still valid and get it if required.
|
|
*/
|
|
if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
|
|
spin_lock(&fs->lock);
|
|
if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry)
|
|
goto unlock_and_drop_dentry;
|
|
path_get(&nd->root);
|
|
spin_unlock(&fs->lock);
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
return 0;
|
|
|
|
unlock_and_drop_dentry:
|
|
spin_unlock(&fs->lock);
|
|
drop_dentry:
|
|
rcu_read_unlock();
|
|
dput(dentry);
|
|
goto drop_root_mnt;
|
|
out:
|
|
rcu_read_unlock();
|
|
drop_root_mnt:
|
|
if (!(nd->flags & LOOKUP_ROOT))
|
|
nd->root.mnt = NULL;
|
|
return -ECHILD;
|
|
}
|
|
|
|
static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
|
|
{
|
|
return dentry->d_op->d_revalidate(dentry, flags);
|
|
}
|
|
|
|
/**
|
|
* complete_walk - successful completion of path walk
|
|
* @nd: pointer nameidata
|
|
*
|
|
* If we had been in RCU mode, drop out of it and legitimize nd->path.
|
|
* Revalidate the final result, unless we'd already done that during
|
|
* the path walk or the filesystem doesn't ask for it. Return 0 on
|
|
* success, -error on failure. In case of failure caller does not
|
|
* need to drop nd->path.
|
|
*/
|
|
static int complete_walk(struct nameidata *nd)
|
|
{
|
|
struct dentry *dentry = nd->path.dentry;
|
|
int status;
|
|
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
if (!(nd->flags & LOOKUP_ROOT))
|
|
nd->root.mnt = NULL;
|
|
|
|
if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) {
|
|
rcu_read_unlock();
|
|
return -ECHILD;
|
|
}
|
|
if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) {
|
|
rcu_read_unlock();
|
|
mntput(nd->path.mnt);
|
|
return -ECHILD;
|
|
}
|
|
if (read_seqcount_retry(&dentry->d_seq, nd->seq)) {
|
|
rcu_read_unlock();
|
|
dput(dentry);
|
|
mntput(nd->path.mnt);
|
|
return -ECHILD;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
if (likely(!(nd->flags & LOOKUP_JUMPED)))
|
|
return 0;
|
|
|
|
if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
|
|
return 0;
|
|
|
|
status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
|
|
if (status > 0)
|
|
return 0;
|
|
|
|
if (!status)
|
|
status = -ESTALE;
|
|
|
|
path_put(&nd->path);
|
|
return status;
|
|
}
|
|
|
|
static __always_inline void set_root(struct nameidata *nd)
|
|
{
|
|
if (!nd->root.mnt)
|
|
get_fs_root(current->fs, &nd->root);
|
|
}
|
|
|
|
static int link_path_walk(const char *, struct nameidata *);
|
|
|
|
static __always_inline void set_root_rcu(struct nameidata *nd)
|
|
{
|
|
if (!nd->root.mnt) {
|
|
struct fs_struct *fs = current->fs;
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
nd->root = fs->root;
|
|
nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
}
|
|
}
|
|
|
|
static void path_put_conditional(struct path *path, struct nameidata *nd)
|
|
{
|
|
dput(path->dentry);
|
|
if (path->mnt != nd->path.mnt)
|
|
mntput(path->mnt);
|
|
}
|
|
|
|
static inline void path_to_nameidata(const struct path *path,
|
|
struct nameidata *nd)
|
|
{
|
|
if (!(nd->flags & LOOKUP_RCU)) {
|
|
dput(nd->path.dentry);
|
|
if (nd->path.mnt != path->mnt)
|
|
mntput(nd->path.mnt);
|
|
}
|
|
nd->path.mnt = path->mnt;
|
|
nd->path.dentry = path->dentry;
|
|
}
|
|
|
|
/*
|
|
* Helper to directly jump to a known parsed path from ->follow_link,
|
|
* caller must have taken a reference to path beforehand.
|
|
*/
|
|
void nd_jump_link(struct nameidata *nd, struct path *path)
|
|
{
|
|
path_put(&nd->path);
|
|
|
|
nd->path = *path;
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
}
|
|
|
|
static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
|
|
{
|
|
struct inode *inode = link->dentry->d_inode;
|
|
if (inode->i_op->put_link)
|
|
inode->i_op->put_link(link->dentry, nd, cookie);
|
|
path_put(link);
|
|
}
|
|
|
|
int sysctl_protected_symlinks __read_mostly = 0;
|
|
int sysctl_protected_hardlinks __read_mostly = 0;
|
|
|
|
/**
|
|
* may_follow_link - Check symlink following for unsafe situations
|
|
* @link: The path of the symlink
|
|
* @nd: nameidata pathwalk data
|
|
*
|
|
* In the case of the sysctl_protected_symlinks sysctl being enabled,
|
|
* CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
|
|
* in a sticky world-writable directory. This is to protect privileged
|
|
* processes from failing races against path names that may change out
|
|
* from under them by way of other users creating malicious symlinks.
|
|
* It will permit symlinks to be followed only when outside a sticky
|
|
* world-writable directory, or when the uid of the symlink and follower
|
|
* match, or when the directory owner matches the symlink's owner.
|
|
*
|
|
* Returns 0 if following the symlink is allowed, -ve on error.
|
|
*/
|
|
static inline int may_follow_link(struct path *link, struct nameidata *nd)
|
|
{
|
|
const struct inode *inode;
|
|
const struct inode *parent;
|
|
|
|
if (!sysctl_protected_symlinks)
|
|
return 0;
|
|
|
|
/* Allowed if owner and follower match. */
|
|
inode = link->dentry->d_inode;
|
|
if (uid_eq(current_cred()->fsuid, inode->i_uid))
|
|
return 0;
|
|
|
|
/* Allowed if parent directory not sticky and world-writable. */
|
|
parent = nd->path.dentry->d_inode;
|
|
if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
|
|
return 0;
|
|
|
|
/* Allowed if parent directory and link owner match. */
|
|
if (uid_eq(parent->i_uid, inode->i_uid))
|
|
return 0;
|
|
|
|
audit_log_link_denied("follow_link", link);
|
|
path_put_conditional(link, nd);
|
|
path_put(&nd->path);
|
|
return -EACCES;
|
|
}
|
|
|
|
/**
|
|
* safe_hardlink_source - Check for safe hardlink conditions
|
|
* @inode: the source inode to hardlink from
|
|
*
|
|
* Return false if at least one of the following conditions:
|
|
* - inode is not a regular file
|
|
* - inode is setuid
|
|
* - inode is setgid and group-exec
|
|
* - access failure for read and write
|
|
*
|
|
* Otherwise returns true.
|
|
*/
|
|
static bool safe_hardlink_source(struct inode *inode)
|
|
{
|
|
umode_t mode = inode->i_mode;
|
|
|
|
/* Special files should not get pinned to the filesystem. */
|
|
if (!S_ISREG(mode))
|
|
return false;
|
|
|
|
/* Setuid files should not get pinned to the filesystem. */
|
|
if (mode & S_ISUID)
|
|
return false;
|
|
|
|
/* Executable setgid files should not get pinned to the filesystem. */
|
|
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
|
|
return false;
|
|
|
|
/* Hardlinking to unreadable or unwritable sources is dangerous. */
|
|
if (inode_permission(inode, MAY_READ | MAY_WRITE))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* may_linkat - Check permissions for creating a hardlink
|
|
* @link: the source to hardlink from
|
|
*
|
|
* Block hardlink when all of:
|
|
* - sysctl_protected_hardlinks enabled
|
|
* - fsuid does not match inode
|
|
* - hardlink source is unsafe (see safe_hardlink_source() above)
|
|
* - not CAP_FOWNER
|
|
*
|
|
* Returns 0 if successful, -ve on error.
|
|
*/
|
|
static int may_linkat(struct path *link)
|
|
{
|
|
const struct cred *cred;
|
|
struct inode *inode;
|
|
|
|
if (!sysctl_protected_hardlinks)
|
|
return 0;
|
|
|
|
cred = current_cred();
|
|
inode = link->dentry->d_inode;
|
|
|
|
/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
|
|
* otherwise, it must be a safe source.
|
|
*/
|
|
if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) ||
|
|
capable(CAP_FOWNER))
|
|
return 0;
|
|
|
|
audit_log_link_denied("linkat", link);
|
|
return -EPERM;
|
|
}
|
|
|
|
static __always_inline int
|
|
follow_link(struct path *link, struct nameidata *nd, void **p)
|
|
{
|
|
struct dentry *dentry = link->dentry;
|
|
int error;
|
|
char *s;
|
|
|
|
BUG_ON(nd->flags & LOOKUP_RCU);
|
|
|
|
if (link->mnt == nd->path.mnt)
|
|
mntget(link->mnt);
|
|
|
|
error = -ELOOP;
|
|
if (unlikely(current->total_link_count >= 40))
|
|
goto out_put_nd_path;
|
|
|
|
cond_resched();
|
|
current->total_link_count++;
|
|
|
|
touch_atime(link);
|
|
nd_set_link(nd, NULL);
|
|
|
|
error = security_inode_follow_link(link->dentry, nd);
|
|
if (error)
|
|
goto out_put_nd_path;
|
|
|
|
nd->last_type = LAST_BIND;
|
|
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
|
|
error = PTR_ERR(*p);
|
|
if (IS_ERR(*p))
|
|
goto out_put_nd_path;
|
|
|
|
error = 0;
|
|
s = nd_get_link(nd);
|
|
if (s) {
|
|
if (unlikely(IS_ERR(s))) {
|
|
path_put(&nd->path);
|
|
put_link(nd, link, *p);
|
|
return PTR_ERR(s);
|
|
}
|
|
if (*s == '/') {
|
|
set_root(nd);
|
|
path_put(&nd->path);
|
|
nd->path = nd->root;
|
|
path_get(&nd->root);
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
}
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
error = link_path_walk(s, nd);
|
|
if (unlikely(error))
|
|
put_link(nd, link, *p);
|
|
}
|
|
|
|
return error;
|
|
|
|
out_put_nd_path:
|
|
*p = NULL;
|
|
path_put(&nd->path);
|
|
path_put(link);
|
|
return error;
|
|
}
|
|
|
|
static int follow_up_rcu(struct path *path)
|
|
{
|
|
struct mount *mnt = real_mount(path->mnt);
|
|
struct mount *parent;
|
|
struct dentry *mountpoint;
|
|
|
|
parent = mnt->mnt_parent;
|
|
if (&parent->mnt == path->mnt)
|
|
return 0;
|
|
mountpoint = mnt->mnt_mountpoint;
|
|
path->dentry = mountpoint;
|
|
path->mnt = &parent->mnt;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* follow_up - Find the mountpoint of path's vfsmount
|
|
*
|
|
* Given a path, find the mountpoint of its source file system.
|
|
* Replace @path with the path of the mountpoint in the parent mount.
|
|
* Up is towards /.
|
|
*
|
|
* Return 1 if we went up a level and 0 if we were already at the
|
|
* root.
|
|
*/
|
|
int follow_up(struct path *path)
|
|
{
|
|
struct mount *mnt = real_mount(path->mnt);
|
|
struct mount *parent;
|
|
struct dentry *mountpoint;
|
|
|
|
read_seqlock_excl(&mount_lock);
|
|
parent = mnt->mnt_parent;
|
|
if (parent == mnt) {
|
|
read_sequnlock_excl(&mount_lock);
|
|
return 0;
|
|
}
|
|
mntget(&parent->mnt);
|
|
mountpoint = dget(mnt->mnt_mountpoint);
|
|
read_sequnlock_excl(&mount_lock);
|
|
dput(path->dentry);
|
|
path->dentry = mountpoint;
|
|
mntput(path->mnt);
|
|
path->mnt = &parent->mnt;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Perform an automount
|
|
* - return -EISDIR to tell follow_managed() to stop and return the path we
|
|
* were called with.
|
|
*/
|
|
static int follow_automount(struct path *path, unsigned flags,
|
|
bool *need_mntput)
|
|
{
|
|
struct vfsmount *mnt;
|
|
int err;
|
|
|
|
if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
|
|
return -EREMOTE;
|
|
|
|
/* We don't want to mount if someone's just doing a stat -
|
|
* unless they're stat'ing a directory and appended a '/' to
|
|
* the name.
|
|
*
|
|
* We do, however, want to mount if someone wants to open or
|
|
* create a file of any type under the mountpoint, wants to
|
|
* traverse through the mountpoint or wants to open the
|
|
* mounted directory. Also, autofs may mark negative dentries
|
|
* as being automount points. These will need the attentions
|
|
* of the daemon to instantiate them before they can be used.
|
|
*/
|
|
if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
|
|
LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
|
|
path->dentry->d_inode)
|
|
return -EISDIR;
|
|
|
|
current->total_link_count++;
|
|
if (current->total_link_count >= 40)
|
|
return -ELOOP;
|
|
|
|
mnt = path->dentry->d_op->d_automount(path);
|
|
if (IS_ERR(mnt)) {
|
|
/*
|
|
* The filesystem is allowed to return -EISDIR here to indicate
|
|
* it doesn't want to automount. For instance, autofs would do
|
|
* this so that its userspace daemon can mount on this dentry.
|
|
*
|
|
* However, we can only permit this if it's a terminal point in
|
|
* the path being looked up; if it wasn't then the remainder of
|
|
* the path is inaccessible and we should say so.
|
|
*/
|
|
if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
|
|
return -EREMOTE;
|
|
return PTR_ERR(mnt);
|
|
}
|
|
|
|
if (!mnt) /* mount collision */
|
|
return 0;
|
|
|
|
if (!*need_mntput) {
|
|
/* lock_mount() may release path->mnt on error */
|
|
mntget(path->mnt);
|
|
*need_mntput = true;
|
|
}
|
|
err = finish_automount(mnt, path);
|
|
|
|
switch (err) {
|
|
case -EBUSY:
|
|
/* Someone else made a mount here whilst we were busy */
|
|
return 0;
|
|
case 0:
|
|
path_put(path);
|
|
path->mnt = mnt;
|
|
path->dentry = dget(mnt->mnt_root);
|
|
return 0;
|
|
default:
|
|
return err;
|
|
}
|
|
|
|
}
|
|
|
|
/*
|
|
* Handle a dentry that is managed in some way.
|
|
* - Flagged for transit management (autofs)
|
|
* - Flagged as mountpoint
|
|
* - Flagged as automount point
|
|
*
|
|
* This may only be called in refwalk mode.
|
|
*
|
|
* Serialization is taken care of in namespace.c
|
|
*/
|
|
static int follow_managed(struct path *path, unsigned flags)
|
|
{
|
|
struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
|
|
unsigned managed;
|
|
bool need_mntput = false;
|
|
int ret = 0;
|
|
|
|
/* Given that we're not holding a lock here, we retain the value in a
|
|
* local variable for each dentry as we look at it so that we don't see
|
|
* the components of that value change under us */
|
|
while (managed = ACCESS_ONCE(path->dentry->d_flags),
|
|
managed &= DCACHE_MANAGED_DENTRY,
|
|
unlikely(managed != 0)) {
|
|
/* Allow the filesystem to manage the transit without i_mutex
|
|
* being held. */
|
|
if (managed & DCACHE_MANAGE_TRANSIT) {
|
|
BUG_ON(!path->dentry->d_op);
|
|
BUG_ON(!path->dentry->d_op->d_manage);
|
|
ret = path->dentry->d_op->d_manage(path->dentry, false);
|
|
if (ret < 0)
|
|
break;
|
|
}
|
|
|
|
/* Transit to a mounted filesystem. */
|
|
if (managed & DCACHE_MOUNTED) {
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (mounted) {
|
|
dput(path->dentry);
|
|
if (need_mntput)
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
need_mntput = true;
|
|
continue;
|
|
}
|
|
|
|
/* Something is mounted on this dentry in another
|
|
* namespace and/or whatever was mounted there in this
|
|
* namespace got unmounted before lookup_mnt() could
|
|
* get it */
|
|
}
|
|
|
|
/* Handle an automount point */
|
|
if (managed & DCACHE_NEED_AUTOMOUNT) {
|
|
ret = follow_automount(path, flags, &need_mntput);
|
|
if (ret < 0)
|
|
break;
|
|
continue;
|
|
}
|
|
|
|
/* We didn't change the current path point */
|
|
break;
|
|
}
|
|
|
|
if (need_mntput && path->mnt == mnt)
|
|
mntput(path->mnt);
|
|
if (ret == -EISDIR)
|
|
ret = 0;
|
|
return ret < 0 ? ret : need_mntput;
|
|
}
|
|
|
|
int follow_down_one(struct path *path)
|
|
{
|
|
struct vfsmount *mounted;
|
|
|
|
mounted = lookup_mnt(path);
|
|
if (mounted) {
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static inline bool managed_dentry_might_block(struct dentry *dentry)
|
|
{
|
|
return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
|
|
dentry->d_op->d_manage(dentry, true) < 0);
|
|
}
|
|
|
|
/*
|
|
* Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
|
|
* we meet a managed dentry that would need blocking.
|
|
*/
|
|
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
|
|
struct inode **inode)
|
|
{
|
|
for (;;) {
|
|
struct mount *mounted;
|
|
/*
|
|
* Don't forget we might have a non-mountpoint managed dentry
|
|
* that wants to block transit.
|
|
*/
|
|
if (unlikely(managed_dentry_might_block(path->dentry)))
|
|
return false;
|
|
|
|
if (!d_mountpoint(path->dentry))
|
|
break;
|
|
|
|
mounted = __lookup_mnt(path->mnt, path->dentry);
|
|
if (!mounted)
|
|
break;
|
|
path->mnt = &mounted->mnt;
|
|
path->dentry = mounted->mnt.mnt_root;
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
|
|
/*
|
|
* Update the inode too. We don't need to re-check the
|
|
* dentry sequence number here after this d_inode read,
|
|
* because a mount-point is always pinned.
|
|
*/
|
|
*inode = path->dentry->d_inode;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static void follow_mount_rcu(struct nameidata *nd)
|
|
{
|
|
while (d_mountpoint(nd->path.dentry)) {
|
|
struct mount *mounted;
|
|
mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
|
|
if (!mounted)
|
|
break;
|
|
nd->path.mnt = &mounted->mnt;
|
|
nd->path.dentry = mounted->mnt.mnt_root;
|
|
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
}
|
|
}
|
|
|
|
static int follow_dotdot_rcu(struct nameidata *nd)
|
|
{
|
|
set_root_rcu(nd);
|
|
|
|
while (1) {
|
|
if (nd->path.dentry == nd->root.dentry &&
|
|
nd->path.mnt == nd->root.mnt) {
|
|
break;
|
|
}
|
|
if (nd->path.dentry != nd->path.mnt->mnt_root) {
|
|
struct dentry *old = nd->path.dentry;
|
|
struct dentry *parent = old->d_parent;
|
|
unsigned seq;
|
|
|
|
seq = read_seqcount_begin(&parent->d_seq);
|
|
if (read_seqcount_retry(&old->d_seq, nd->seq))
|
|
goto failed;
|
|
nd->path.dentry = parent;
|
|
nd->seq = seq;
|
|
break;
|
|
}
|
|
if (!follow_up_rcu(&nd->path))
|
|
break;
|
|
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
}
|
|
follow_mount_rcu(nd);
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
return 0;
|
|
|
|
failed:
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
if (!(nd->flags & LOOKUP_ROOT))
|
|
nd->root.mnt = NULL;
|
|
rcu_read_unlock();
|
|
return -ECHILD;
|
|
}
|
|
|
|
/*
|
|
* Follow down to the covering mount currently visible to userspace. At each
|
|
* point, the filesystem owning that dentry may be queried as to whether the
|
|
* caller is permitted to proceed or not.
|
|
*/
|
|
int follow_down(struct path *path)
|
|
{
|
|
unsigned managed;
|
|
int ret;
|
|
|
|
while (managed = ACCESS_ONCE(path->dentry->d_flags),
|
|
unlikely(managed & DCACHE_MANAGED_DENTRY)) {
|
|
/* Allow the filesystem to manage the transit without i_mutex
|
|
* being held.
|
|
*
|
|
* We indicate to the filesystem if someone is trying to mount
|
|
* something here. This gives autofs the chance to deny anyone
|
|
* other than its daemon the right to mount on its
|
|
* superstructure.
|
|
*
|
|
* The filesystem may sleep at this point.
|
|
*/
|
|
if (managed & DCACHE_MANAGE_TRANSIT) {
|
|
BUG_ON(!path->dentry->d_op);
|
|
BUG_ON(!path->dentry->d_op->d_manage);
|
|
ret = path->dentry->d_op->d_manage(
|
|
path->dentry, false);
|
|
if (ret < 0)
|
|
return ret == -EISDIR ? 0 : ret;
|
|
}
|
|
|
|
/* Transit to a mounted filesystem. */
|
|
if (managed & DCACHE_MOUNTED) {
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (!mounted)
|
|
break;
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
continue;
|
|
}
|
|
|
|
/* Don't handle automount points here */
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
|
|
*/
|
|
static void follow_mount(struct path *path)
|
|
{
|
|
while (d_mountpoint(path->dentry)) {
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (!mounted)
|
|
break;
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
}
|
|
}
|
|
|
|
static void follow_dotdot(struct nameidata *nd)
|
|
{
|
|
set_root(nd);
|
|
|
|
while(1) {
|
|
struct dentry *old = nd->path.dentry;
|
|
|
|
if (nd->path.dentry == nd->root.dentry &&
|
|
nd->path.mnt == nd->root.mnt) {
|
|
break;
|
|
}
|
|
if (nd->path.dentry != nd->path.mnt->mnt_root) {
|
|
/* rare case of legitimate dget_parent()... */
|
|
nd->path.dentry = dget_parent(nd->path.dentry);
|
|
dput(old);
|
|
break;
|
|
}
|
|
if (!follow_up(&nd->path))
|
|
break;
|
|
}
|
|
follow_mount(&nd->path);
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
}
|
|
|
|
/*
|
|
* This looks up the name in dcache, possibly revalidates the old dentry and
|
|
* allocates a new one if not found or not valid. In the need_lookup argument
|
|
* returns whether i_op->lookup is necessary.
|
|
*
|
|
* dir->d_inode->i_mutex must be held
|
|
*/
|
|
static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir,
|
|
unsigned int flags, bool *need_lookup)
|
|
{
|
|
struct dentry *dentry;
|
|
int error;
|
|
|
|
*need_lookup = false;
|
|
dentry = d_lookup(dir, name);
|
|
if (dentry) {
|
|
if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
|
|
error = d_revalidate(dentry, flags);
|
|
if (unlikely(error <= 0)) {
|
|
if (error < 0) {
|
|
dput(dentry);
|
|
return ERR_PTR(error);
|
|
} else if (!d_invalidate(dentry)) {
|
|
dput(dentry);
|
|
dentry = NULL;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!dentry) {
|
|
dentry = d_alloc(dir, name);
|
|
if (unlikely(!dentry))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
*need_lookup = true;
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
/*
|
|
* Call i_op->lookup on the dentry. The dentry must be negative and
|
|
* unhashed.
|
|
*
|
|
* dir->d_inode->i_mutex must be held
|
|
*/
|
|
static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
|
|
unsigned int flags)
|
|
{
|
|
struct dentry *old;
|
|
|
|
/* Don't create child dentry for a dead directory. */
|
|
if (unlikely(IS_DEADDIR(dir))) {
|
|
dput(dentry);
|
|
return ERR_PTR(-ENOENT);
|
|
}
|
|
|
|
old = dir->i_op->lookup(dir, dentry, flags);
|
|
if (unlikely(old)) {
|
|
dput(dentry);
|
|
dentry = old;
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *__lookup_hash(struct qstr *name,
|
|
struct dentry *base, unsigned int flags)
|
|
{
|
|
bool need_lookup;
|
|
struct dentry *dentry;
|
|
|
|
dentry = lookup_dcache(name, base, flags, &need_lookup);
|
|
if (!need_lookup)
|
|
return dentry;
|
|
|
|
return lookup_real(base->d_inode, dentry, flags);
|
|
}
|
|
|
|
/*
|
|
* It's more convoluted than I'd like it to be, but... it's still fairly
|
|
* small and for now I'd prefer to have fast path as straight as possible.
|
|
* It _is_ time-critical.
|
|
*/
|
|
static int lookup_fast(struct nameidata *nd,
|
|
struct path *path, struct inode **inode)
|
|
{
|
|
struct vfsmount *mnt = nd->path.mnt;
|
|
struct dentry *dentry, *parent = nd->path.dentry;
|
|
int need_reval = 1;
|
|
int status = 1;
|
|
int err;
|
|
|
|
/*
|
|
* Rename seqlock is not required here because in the off chance
|
|
* of a false negative due to a concurrent rename, we're going to
|
|
* do the non-racy lookup, below.
|
|
*/
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
unsigned seq;
|
|
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
|
|
if (!dentry)
|
|
goto unlazy;
|
|
|
|
/*
|
|
* This sequence count validates that the inode matches
|
|
* the dentry name information from lookup.
|
|
*/
|
|
*inode = dentry->d_inode;
|
|
if (read_seqcount_retry(&dentry->d_seq, seq))
|
|
return -ECHILD;
|
|
|
|
/*
|
|
* This sequence count validates that the parent had no
|
|
* changes while we did the lookup of the dentry above.
|
|
*
|
|
* The memory barrier in read_seqcount_begin of child is
|
|
* enough, we can use __read_seqcount_retry here.
|
|
*/
|
|
if (__read_seqcount_retry(&parent->d_seq, nd->seq))
|
|
return -ECHILD;
|
|
nd->seq = seq;
|
|
|
|
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
|
|
status = d_revalidate(dentry, nd->flags);
|
|
if (unlikely(status <= 0)) {
|
|
if (status != -ECHILD)
|
|
need_reval = 0;
|
|
goto unlazy;
|
|
}
|
|
}
|
|
path->mnt = mnt;
|
|
path->dentry = dentry;
|
|
if (unlikely(!__follow_mount_rcu(nd, path, inode)))
|
|
goto unlazy;
|
|
if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
|
|
goto unlazy;
|
|
return 0;
|
|
unlazy:
|
|
if (unlazy_walk(nd, dentry))
|
|
return -ECHILD;
|
|
} else {
|
|
dentry = __d_lookup(parent, &nd->last);
|
|
}
|
|
|
|
if (unlikely(!dentry))
|
|
goto need_lookup;
|
|
|
|
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
|
|
status = d_revalidate(dentry, nd->flags);
|
|
if (unlikely(status <= 0)) {
|
|
if (status < 0) {
|
|
dput(dentry);
|
|
return status;
|
|
}
|
|
if (!d_invalidate(dentry)) {
|
|
dput(dentry);
|
|
goto need_lookup;
|
|
}
|
|
}
|
|
|
|
path->mnt = mnt;
|
|
path->dentry = dentry;
|
|
err = follow_managed(path, nd->flags);
|
|
if (unlikely(err < 0)) {
|
|
path_put_conditional(path, nd);
|
|
return err;
|
|
}
|
|
if (err)
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
*inode = path->dentry->d_inode;
|
|
return 0;
|
|
|
|
need_lookup:
|
|
return 1;
|
|
}
|
|
|
|
/* Fast lookup failed, do it the slow way */
|
|
static int lookup_slow(struct nameidata *nd, struct path *path)
|
|
{
|
|
struct dentry *dentry, *parent;
|
|
int err;
|
|
|
|
parent = nd->path.dentry;
|
|
BUG_ON(nd->inode != parent->d_inode);
|
|
|
|
mutex_lock(&parent->d_inode->i_mutex);
|
|
dentry = __lookup_hash(&nd->last, parent, nd->flags);
|
|
mutex_unlock(&parent->d_inode->i_mutex);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
path->mnt = nd->path.mnt;
|
|
path->dentry = dentry;
|
|
err = follow_managed(path, nd->flags);
|
|
if (unlikely(err < 0)) {
|
|
path_put_conditional(path, nd);
|
|
return err;
|
|
}
|
|
if (err)
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
return 0;
|
|
}
|
|
|
|
static inline int may_lookup(struct nameidata *nd)
|
|
{
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
|
|
if (err != -ECHILD)
|
|
return err;
|
|
if (unlazy_walk(nd, NULL))
|
|
return -ECHILD;
|
|
}
|
|
return inode_permission(nd->inode, MAY_EXEC);
|
|
}
|
|
|
|
static inline int handle_dots(struct nameidata *nd, int type)
|
|
{
|
|
if (type == LAST_DOTDOT) {
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (follow_dotdot_rcu(nd))
|
|
return -ECHILD;
|
|
} else
|
|
follow_dotdot(nd);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void terminate_walk(struct nameidata *nd)
|
|
{
|
|
if (!(nd->flags & LOOKUP_RCU)) {
|
|
path_put(&nd->path);
|
|
} else {
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
if (!(nd->flags & LOOKUP_ROOT))
|
|
nd->root.mnt = NULL;
|
|
rcu_read_unlock();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Do we need to follow links? We _really_ want to be able
|
|
* to do this check without having to look at inode->i_op,
|
|
* so we keep a cache of "no, this doesn't need follow_link"
|
|
* for the common case.
|
|
*/
|
|
static inline int should_follow_link(struct dentry *dentry, int follow)
|
|
{
|
|
return unlikely(d_is_symlink(dentry)) ? follow : 0;
|
|
}
|
|
|
|
static inline int walk_component(struct nameidata *nd, struct path *path,
|
|
int follow)
|
|
{
|
|
struct inode *inode;
|
|
int err;
|
|
/*
|
|
* "." and ".." are special - ".." especially so because it has
|
|
* to be able to know about the current root directory and
|
|
* parent relationships.
|
|
*/
|
|
if (unlikely(nd->last_type != LAST_NORM))
|
|
return handle_dots(nd, nd->last_type);
|
|
err = lookup_fast(nd, path, &inode);
|
|
if (unlikely(err)) {
|
|
if (err < 0)
|
|
goto out_err;
|
|
|
|
err = lookup_slow(nd, path);
|
|
if (err < 0)
|
|
goto out_err;
|
|
|
|
inode = path->dentry->d_inode;
|
|
}
|
|
err = -ENOENT;
|
|
if (!inode)
|
|
goto out_path_put;
|
|
|
|
if (should_follow_link(path->dentry, follow)) {
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (unlikely(unlazy_walk(nd, path->dentry))) {
|
|
err = -ECHILD;
|
|
goto out_err;
|
|
}
|
|
}
|
|
BUG_ON(inode != path->dentry->d_inode);
|
|
return 1;
|
|
}
|
|
path_to_nameidata(path, nd);
|
|
nd->inode = inode;
|
|
return 0;
|
|
|
|
out_path_put:
|
|
path_to_nameidata(path, nd);
|
|
out_err:
|
|
terminate_walk(nd);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* This limits recursive symlink follows to 8, while
|
|
* limiting consecutive symlinks to 40.
|
|
*
|
|
* Without that kind of total limit, nasty chains of consecutive
|
|
* symlinks can cause almost arbitrarily long lookups.
|
|
*/
|
|
static inline int nested_symlink(struct path *path, struct nameidata *nd)
|
|
{
|
|
int res;
|
|
|
|
if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
|
|
path_put_conditional(path, nd);
|
|
path_put(&nd->path);
|
|
return -ELOOP;
|
|
}
|
|
BUG_ON(nd->depth >= MAX_NESTED_LINKS);
|
|
|
|
nd->depth++;
|
|
current->link_count++;
|
|
|
|
do {
|
|
struct path link = *path;
|
|
void *cookie;
|
|
|
|
res = follow_link(&link, nd, &cookie);
|
|
if (res)
|
|
break;
|
|
res = walk_component(nd, path, LOOKUP_FOLLOW);
|
|
put_link(nd, &link, cookie);
|
|
} while (res > 0);
|
|
|
|
current->link_count--;
|
|
nd->depth--;
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* We can do the critical dentry name comparison and hashing
|
|
* operations one word at a time, but we are limited to:
|
|
*
|
|
* - Architectures with fast unaligned word accesses. We could
|
|
* do a "get_unaligned()" if this helps and is sufficiently
|
|
* fast.
|
|
*
|
|
* - Little-endian machines (so that we can generate the mask
|
|
* of low bytes efficiently). Again, we *could* do a byte
|
|
* swapping load on big-endian architectures if that is not
|
|
* expensive enough to make the optimization worthless.
|
|
*
|
|
* - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
|
|
* do not trap on the (extremely unlikely) case of a page
|
|
* crossing operation.
|
|
*
|
|
* - Furthermore, we need an efficient 64-bit compile for the
|
|
* 64-bit case in order to generate the "number of bytes in
|
|
* the final mask". Again, that could be replaced with a
|
|
* efficient population count instruction or similar.
|
|
*/
|
|
#ifdef CONFIG_DCACHE_WORD_ACCESS
|
|
|
|
#include <asm/word-at-a-time.h>
|
|
|
|
#ifdef CONFIG_64BIT
|
|
|
|
static inline unsigned int fold_hash(unsigned long hash)
|
|
{
|
|
hash += hash >> (8*sizeof(int));
|
|
return hash;
|
|
}
|
|
|
|
#else /* 32-bit case */
|
|
|
|
#define fold_hash(x) (x)
|
|
|
|
#endif
|
|
|
|
unsigned int full_name_hash(const unsigned char *name, unsigned int len)
|
|
{
|
|
unsigned long a, mask;
|
|
unsigned long hash = 0;
|
|
|
|
for (;;) {
|
|
a = load_unaligned_zeropad(name);
|
|
if (len < sizeof(unsigned long))
|
|
break;
|
|
hash += a;
|
|
hash *= 9;
|
|
name += sizeof(unsigned long);
|
|
len -= sizeof(unsigned long);
|
|
if (!len)
|
|
goto done;
|
|
}
|
|
mask = ~(~0ul << len*8);
|
|
hash += mask & a;
|
|
done:
|
|
return fold_hash(hash);
|
|
}
|
|
EXPORT_SYMBOL(full_name_hash);
|
|
|
|
/*
|
|
* Calculate the length and hash of the path component, and
|
|
* return the length of the component;
|
|
*/
|
|
static inline unsigned long hash_name(const char *name, unsigned int *hashp)
|
|
{
|
|
unsigned long a, b, adata, bdata, mask, hash, len;
|
|
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
|
|
|
hash = a = 0;
|
|
len = -sizeof(unsigned long);
|
|
do {
|
|
hash = (hash + a) * 9;
|
|
len += sizeof(unsigned long);
|
|
a = load_unaligned_zeropad(name+len);
|
|
b = a ^ REPEAT_BYTE('/');
|
|
} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
|
|
|
|
adata = prep_zero_mask(a, adata, &constants);
|
|
bdata = prep_zero_mask(b, bdata, &constants);
|
|
|
|
mask = create_zero_mask(adata | bdata);
|
|
|
|
hash += a & zero_bytemask(mask);
|
|
*hashp = fold_hash(hash);
|
|
|
|
return len + find_zero(mask);
|
|
}
|
|
|
|
#else
|
|
|
|
unsigned int full_name_hash(const unsigned char *name, unsigned int len)
|
|
{
|
|
unsigned long hash = init_name_hash();
|
|
while (len--)
|
|
hash = partial_name_hash(*name++, hash);
|
|
return end_name_hash(hash);
|
|
}
|
|
EXPORT_SYMBOL(full_name_hash);
|
|
|
|
/*
|
|
* We know there's a real path component here of at least
|
|
* one character.
|
|
*/
|
|
static inline unsigned long hash_name(const char *name, unsigned int *hashp)
|
|
{
|
|
unsigned long hash = init_name_hash();
|
|
unsigned long len = 0, c;
|
|
|
|
c = (unsigned char)*name;
|
|
do {
|
|
len++;
|
|
hash = partial_name_hash(c, hash);
|
|
c = (unsigned char)name[len];
|
|
} while (c && c != '/');
|
|
*hashp = end_name_hash(hash);
|
|
return len;
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Name resolution.
|
|
* This is the basic name resolution function, turning a pathname into
|
|
* the final dentry. We expect 'base' to be positive and a directory.
|
|
*
|
|
* Returns 0 and nd will have valid dentry and mnt on success.
|
|
* Returns error and drops reference to input namei data on failure.
|
|
*/
|
|
static int link_path_walk(const char *name, struct nameidata *nd)
|
|
{
|
|
struct path next;
|
|
int err;
|
|
|
|
while (*name=='/')
|
|
name++;
|
|
if (!*name)
|
|
return 0;
|
|
|
|
/* At this point we know we have a real path component. */
|
|
for(;;) {
|
|
struct qstr this;
|
|
long len;
|
|
int type;
|
|
|
|
err = may_lookup(nd);
|
|
if (err)
|
|
break;
|
|
|
|
len = hash_name(name, &this.hash);
|
|
this.name = name;
|
|
this.len = len;
|
|
|
|
type = LAST_NORM;
|
|
if (name[0] == '.') switch (len) {
|
|
case 2:
|
|
if (name[1] == '.') {
|
|
type = LAST_DOTDOT;
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
}
|
|
break;
|
|
case 1:
|
|
type = LAST_DOT;
|
|
}
|
|
if (likely(type == LAST_NORM)) {
|
|
struct dentry *parent = nd->path.dentry;
|
|
nd->flags &= ~LOOKUP_JUMPED;
|
|
if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
|
|
err = parent->d_op->d_hash(parent, &this);
|
|
if (err < 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
nd->last = this;
|
|
nd->last_type = type;
|
|
|
|
if (!name[len])
|
|
return 0;
|
|
/*
|
|
* If it wasn't NUL, we know it was '/'. Skip that
|
|
* slash, and continue until no more slashes.
|
|
*/
|
|
do {
|
|
len++;
|
|
} while (unlikely(name[len] == '/'));
|
|
if (!name[len])
|
|
return 0;
|
|
|
|
name += len;
|
|
|
|
err = walk_component(nd, &next, LOOKUP_FOLLOW);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
if (err) {
|
|
err = nested_symlink(&next, nd);
|
|
if (err)
|
|
return err;
|
|
}
|
|
if (!d_is_directory(nd->path.dentry)) {
|
|
err = -ENOTDIR;
|
|
break;
|
|
}
|
|
}
|
|
terminate_walk(nd);
|
|
return err;
|
|
}
|
|
|
|
static int path_init(int dfd, const char *name, unsigned int flags,
|
|
struct nameidata *nd, struct file **fp)
|
|
{
|
|
int retval = 0;
|
|
|
|
nd->last_type = LAST_ROOT; /* if there are only slashes... */
|
|
nd->flags = flags | LOOKUP_JUMPED;
|
|
nd->depth = 0;
|
|
if (flags & LOOKUP_ROOT) {
|
|
struct dentry *root = nd->root.dentry;
|
|
struct inode *inode = root->d_inode;
|
|
if (*name) {
|
|
if (!d_is_directory(root))
|
|
return -ENOTDIR;
|
|
retval = inode_permission(inode, MAY_EXEC);
|
|
if (retval)
|
|
return retval;
|
|
}
|
|
nd->path = nd->root;
|
|
nd->inode = inode;
|
|
if (flags & LOOKUP_RCU) {
|
|
rcu_read_lock();
|
|
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
nd->m_seq = read_seqbegin(&mount_lock);
|
|
} else {
|
|
path_get(&nd->path);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
nd->root.mnt = NULL;
|
|
|
|
nd->m_seq = read_seqbegin(&mount_lock);
|
|
if (*name=='/') {
|
|
if (flags & LOOKUP_RCU) {
|
|
rcu_read_lock();
|
|
set_root_rcu(nd);
|
|
} else {
|
|
set_root(nd);
|
|
path_get(&nd->root);
|
|
}
|
|
nd->path = nd->root;
|
|
} else if (dfd == AT_FDCWD) {
|
|
if (flags & LOOKUP_RCU) {
|
|
struct fs_struct *fs = current->fs;
|
|
unsigned seq;
|
|
|
|
rcu_read_lock();
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
nd->path = fs->pwd;
|
|
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
} else {
|
|
get_fs_pwd(current->fs, &nd->path);
|
|
}
|
|
} else {
|
|
/* Caller must check execute permissions on the starting path component */
|
|
struct fd f = fdget_raw(dfd);
|
|
struct dentry *dentry;
|
|
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
dentry = f.file->f_path.dentry;
|
|
|
|
if (*name) {
|
|
if (!d_is_directory(dentry)) {
|
|
fdput(f);
|
|
return -ENOTDIR;
|
|
}
|
|
}
|
|
|
|
nd->path = f.file->f_path;
|
|
if (flags & LOOKUP_RCU) {
|
|
if (f.need_put)
|
|
*fp = f.file;
|
|
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
rcu_read_lock();
|
|
} else {
|
|
path_get(&nd->path);
|
|
fdput(f);
|
|
}
|
|
}
|
|
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
return 0;
|
|
}
|
|
|
|
static inline int lookup_last(struct nameidata *nd, struct path *path)
|
|
{
|
|
if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
|
|
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
|
|
nd->flags &= ~LOOKUP_PARENT;
|
|
return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW);
|
|
}
|
|
|
|
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
|
|
static int path_lookupat(int dfd, const char *name,
|
|
unsigned int flags, struct nameidata *nd)
|
|
{
|
|
struct file *base = NULL;
|
|
struct path path;
|
|
int err;
|
|
|
|
/*
|
|
* Path walking is largely split up into 2 different synchronisation
|
|
* schemes, rcu-walk and ref-walk (explained in
|
|
* Documentation/filesystems/path-lookup.txt). These share much of the
|
|
* path walk code, but some things particularly setup, cleanup, and
|
|
* following mounts are sufficiently divergent that functions are
|
|
* duplicated. Typically there is a function foo(), and its RCU
|
|
* analogue, foo_rcu().
|
|
*
|
|
* -ECHILD is the error number of choice (just to avoid clashes) that
|
|
* is returned if some aspect of an rcu-walk fails. Such an error must
|
|
* be handled by restarting a traditional ref-walk (which will always
|
|
* be able to complete).
|
|
*/
|
|
err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
|
|
|
|
if (unlikely(err))
|
|
return err;
|
|
|
|
current->total_link_count = 0;
|
|
err = link_path_walk(name, nd);
|
|
|
|
if (!err && !(flags & LOOKUP_PARENT)) {
|
|
err = lookup_last(nd, &path);
|
|
while (err > 0) {
|
|
void *cookie;
|
|
struct path link = path;
|
|
err = may_follow_link(&link, nd);
|
|
if (unlikely(err))
|
|
break;
|
|
nd->flags |= LOOKUP_PARENT;
|
|
err = follow_link(&link, nd, &cookie);
|
|
if (err)
|
|
break;
|
|
err = lookup_last(nd, &path);
|
|
put_link(nd, &link, cookie);
|
|
}
|
|
}
|
|
|
|
if (!err)
|
|
err = complete_walk(nd);
|
|
|
|
if (!err && nd->flags & LOOKUP_DIRECTORY) {
|
|
if (!d_is_directory(nd->path.dentry)) {
|
|
path_put(&nd->path);
|
|
err = -ENOTDIR;
|
|
}
|
|
}
|
|
|
|
if (base)
|
|
fput(base);
|
|
|
|
if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
|
|
path_put(&nd->root);
|
|
nd->root.mnt = NULL;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int filename_lookup(int dfd, struct filename *name,
|
|
unsigned int flags, struct nameidata *nd)
|
|
{
|
|
int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd);
|
|
if (unlikely(retval == -ECHILD))
|
|
retval = path_lookupat(dfd, name->name, flags, nd);
|
|
if (unlikely(retval == -ESTALE))
|
|
retval = path_lookupat(dfd, name->name,
|
|
flags | LOOKUP_REVAL, nd);
|
|
|
|
if (likely(!retval))
|
|
audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT);
|
|
return retval;
|
|
}
|
|
|
|
static int do_path_lookup(int dfd, const char *name,
|
|
unsigned int flags, struct nameidata *nd)
|
|
{
|
|
struct filename filename = { .name = name };
|
|
|
|
return filename_lookup(dfd, &filename, flags, nd);
|
|
}
|
|
|
|
/* does lookup, returns the object with parent locked */
|
|
struct dentry *kern_path_locked(const char *name, struct path *path)
|
|
{
|
|
struct nameidata nd;
|
|
struct dentry *d;
|
|
int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
if (nd.last_type != LAST_NORM) {
|
|
path_put(&nd.path);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
d = __lookup_hash(&nd.last, nd.path.dentry, 0);
|
|
if (IS_ERR(d)) {
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
path_put(&nd.path);
|
|
return d;
|
|
}
|
|
*path = nd.path;
|
|
return d;
|
|
}
|
|
|
|
int kern_path(const char *name, unsigned int flags, struct path *path)
|
|
{
|
|
struct nameidata nd;
|
|
int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
|
|
if (!res)
|
|
*path = nd.path;
|
|
return res;
|
|
}
|
|
|
|
/**
|
|
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mnt: pointer to vfs mount of the base directory
|
|
* @name: pointer to file name
|
|
* @flags: lookup flags
|
|
* @path: pointer to struct path to fill
|
|
*/
|
|
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *name, unsigned int flags,
|
|
struct path *path)
|
|
{
|
|
struct nameidata nd;
|
|
int err;
|
|
nd.root.dentry = dentry;
|
|
nd.root.mnt = mnt;
|
|
BUG_ON(flags & LOOKUP_PARENT);
|
|
/* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
|
|
err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
|
|
if (!err)
|
|
*path = nd.path;
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Restricted form of lookup. Doesn't follow links, single-component only,
|
|
* needs parent already locked. Doesn't follow mounts.
|
|
* SMP-safe.
|
|
*/
|
|
static struct dentry *lookup_hash(struct nameidata *nd)
|
|
{
|
|
return __lookup_hash(&nd->last, nd->path.dentry, nd->flags);
|
|
}
|
|
|
|
/**
|
|
* lookup_one_len - filesystem helper to lookup single pathname component
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code. Also note that by using this function the
|
|
* nameidata argument is passed to the filesystem methods and a filesystem
|
|
* using this helper needs to be prepared for that.
|
|
*/
|
|
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
|
|
{
|
|
struct qstr this;
|
|
unsigned int c;
|
|
int err;
|
|
|
|
WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
|
|
|
|
this.name = name;
|
|
this.len = len;
|
|
this.hash = full_name_hash(name, len);
|
|
if (!len)
|
|
return ERR_PTR(-EACCES);
|
|
|
|
if (unlikely(name[0] == '.')) {
|
|
if (len < 2 || (len == 2 && name[1] == '.'))
|
|
return ERR_PTR(-EACCES);
|
|
}
|
|
|
|
while (len--) {
|
|
c = *(const unsigned char *)name++;
|
|
if (c == '/' || c == '\0')
|
|
return ERR_PTR(-EACCES);
|
|
}
|
|
/*
|
|
* See if the low-level filesystem might want
|
|
* to use its own hash..
|
|
*/
|
|
if (base->d_flags & DCACHE_OP_HASH) {
|
|
int err = base->d_op->d_hash(base, &this);
|
|
if (err < 0)
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
err = inode_permission(base->d_inode, MAY_EXEC);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
return __lookup_hash(&this, base, 0);
|
|
}
|
|
|
|
int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
|
|
struct path *path, int *empty)
|
|
{
|
|
struct nameidata nd;
|
|
struct filename *tmp = getname_flags(name, flags, empty);
|
|
int err = PTR_ERR(tmp);
|
|
if (!IS_ERR(tmp)) {
|
|
|
|
BUG_ON(flags & LOOKUP_PARENT);
|
|
|
|
err = filename_lookup(dfd, tmp, flags, &nd);
|
|
putname(tmp);
|
|
if (!err)
|
|
*path = nd.path;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
int user_path_at(int dfd, const char __user *name, unsigned flags,
|
|
struct path *path)
|
|
{
|
|
return user_path_at_empty(dfd, name, flags, path, NULL);
|
|
}
|
|
|
|
/*
|
|
* NB: most callers don't do anything directly with the reference to the
|
|
* to struct filename, but the nd->last pointer points into the name string
|
|
* allocated by getname. So we must hold the reference to it until all
|
|
* path-walking is complete.
|
|
*/
|
|
static struct filename *
|
|
user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
|
|
unsigned int flags)
|
|
{
|
|
struct filename *s = getname(path);
|
|
int error;
|
|
|
|
/* only LOOKUP_REVAL is allowed in extra flags */
|
|
flags &= LOOKUP_REVAL;
|
|
|
|
if (IS_ERR(s))
|
|
return s;
|
|
|
|
error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd);
|
|
if (error) {
|
|
putname(s);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
/**
|
|
* mountpoint_last - look up last component for umount
|
|
* @nd: pathwalk nameidata - currently pointing at parent directory of "last"
|
|
* @path: pointer to container for result
|
|
*
|
|
* This is a special lookup_last function just for umount. In this case, we
|
|
* need to resolve the path without doing any revalidation.
|
|
*
|
|
* The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
|
|
* mountpoints are always pinned in the dcache, their ancestors are too. Thus,
|
|
* in almost all cases, this lookup will be served out of the dcache. The only
|
|
* cases where it won't are if nd->last refers to a symlink or the path is
|
|
* bogus and it doesn't exist.
|
|
*
|
|
* Returns:
|
|
* -error: if there was an error during lookup. This includes -ENOENT if the
|
|
* lookup found a negative dentry. The nd->path reference will also be
|
|
* put in this case.
|
|
*
|
|
* 0: if we successfully resolved nd->path and found it to not to be a
|
|
* symlink that needs to be followed. "path" will also be populated.
|
|
* The nd->path reference will also be put.
|
|
*
|
|
* 1: if we successfully resolved nd->last and found it to be a symlink
|
|
* that needs to be followed. "path" will be populated with the path
|
|
* to the link, and nd->path will *not* be put.
|
|
*/
|
|
static int
|
|
mountpoint_last(struct nameidata *nd, struct path *path)
|
|
{
|
|
int error = 0;
|
|
struct dentry *dentry;
|
|
struct dentry *dir = nd->path.dentry;
|
|
|
|
/* If we're in rcuwalk, drop out of it to handle last component */
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (unlazy_walk(nd, NULL)) {
|
|
error = -ECHILD;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
nd->flags &= ~LOOKUP_PARENT;
|
|
|
|
if (unlikely(nd->last_type != LAST_NORM)) {
|
|
error = handle_dots(nd, nd->last_type);
|
|
if (error)
|
|
goto out;
|
|
dentry = dget(nd->path.dentry);
|
|
goto done;
|
|
}
|
|
|
|
mutex_lock(&dir->d_inode->i_mutex);
|
|
dentry = d_lookup(dir, &nd->last);
|
|
if (!dentry) {
|
|
/*
|
|
* No cached dentry. Mounted dentries are pinned in the cache,
|
|
* so that means that this dentry is probably a symlink or the
|
|
* path doesn't actually point to a mounted dentry.
|
|
*/
|
|
dentry = d_alloc(dir, &nd->last);
|
|
if (!dentry) {
|
|
error = -ENOMEM;
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
goto out;
|
|
}
|
|
dentry = lookup_real(dir->d_inode, dentry, nd->flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry)) {
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
goto out;
|
|
}
|
|
}
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
|
|
done:
|
|
if (!dentry->d_inode) {
|
|
error = -ENOENT;
|
|
dput(dentry);
|
|
goto out;
|
|
}
|
|
path->dentry = dentry;
|
|
path->mnt = mntget(nd->path.mnt);
|
|
if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW))
|
|
return 1;
|
|
follow_mount(path);
|
|
error = 0;
|
|
out:
|
|
terminate_walk(nd);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* path_mountpoint - look up a path to be umounted
|
|
* @dfd: directory file descriptor to start walk from
|
|
* @name: full pathname to walk
|
|
* @path: pointer to container for result
|
|
* @flags: lookup flags
|
|
*
|
|
* Look up the given name, but don't attempt to revalidate the last component.
|
|
* Returns 0 and "path" will be valid on success; Returns error otherwise.
|
|
*/
|
|
static int
|
|
path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags)
|
|
{
|
|
struct file *base = NULL;
|
|
struct nameidata nd;
|
|
int err;
|
|
|
|
err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base);
|
|
if (unlikely(err))
|
|
return err;
|
|
|
|
current->total_link_count = 0;
|
|
err = link_path_walk(name, &nd);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = mountpoint_last(&nd, path);
|
|
while (err > 0) {
|
|
void *cookie;
|
|
struct path link = *path;
|
|
err = may_follow_link(&link, &nd);
|
|
if (unlikely(err))
|
|
break;
|
|
nd.flags |= LOOKUP_PARENT;
|
|
err = follow_link(&link, &nd, &cookie);
|
|
if (err)
|
|
break;
|
|
err = mountpoint_last(&nd, path);
|
|
put_link(&nd, &link, cookie);
|
|
}
|
|
out:
|
|
if (base)
|
|
fput(base);
|
|
|
|
if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT))
|
|
path_put(&nd.root);
|
|
|
|
return err;
|
|
}
|
|
|
|
static int
|
|
filename_mountpoint(int dfd, struct filename *s, struct path *path,
|
|
unsigned int flags)
|
|
{
|
|
int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU);
|
|
if (unlikely(error == -ECHILD))
|
|
error = path_mountpoint(dfd, s->name, path, flags);
|
|
if (unlikely(error == -ESTALE))
|
|
error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL);
|
|
if (likely(!error))
|
|
audit_inode(s, path->dentry, 0);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* user_path_mountpoint_at - lookup a path from userland in order to umount it
|
|
* @dfd: directory file descriptor
|
|
* @name: pathname from userland
|
|
* @flags: lookup flags
|
|
* @path: pointer to container to hold result
|
|
*
|
|
* A umount is a special case for path walking. We're not actually interested
|
|
* in the inode in this situation, and ESTALE errors can be a problem. We
|
|
* simply want track down the dentry and vfsmount attached at the mountpoint
|
|
* and avoid revalidating the last component.
|
|
*
|
|
* Returns 0 and populates "path" on success.
|
|
*/
|
|
int
|
|
user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
|
|
struct path *path)
|
|
{
|
|
struct filename *s = getname(name);
|
|
int error;
|
|
if (IS_ERR(s))
|
|
return PTR_ERR(s);
|
|
error = filename_mountpoint(dfd, s, path, flags);
|
|
putname(s);
|
|
return error;
|
|
}
|
|
|
|
int
|
|
kern_path_mountpoint(int dfd, const char *name, struct path *path,
|
|
unsigned int flags)
|
|
{
|
|
struct filename s = {.name = name};
|
|
return filename_mountpoint(dfd, &s, path, flags);
|
|
}
|
|
EXPORT_SYMBOL(kern_path_mountpoint);
|
|
|
|
/*
|
|
* It's inline, so penalty for filesystems that don't use sticky bit is
|
|
* minimal.
|
|
*/
|
|
static inline int check_sticky(struct inode *dir, struct inode *inode)
|
|
{
|
|
kuid_t fsuid = current_fsuid();
|
|
|
|
if (!(dir->i_mode & S_ISVTX))
|
|
return 0;
|
|
if (uid_eq(inode->i_uid, fsuid))
|
|
return 0;
|
|
if (uid_eq(dir->i_uid, fsuid))
|
|
return 0;
|
|
return !inode_capable(inode, CAP_FOWNER);
|
|
}
|
|
|
|
/*
|
|
* Check whether we can remove a link victim from directory dir, check
|
|
* whether the type of victim is right.
|
|
* 1. We can't do it if dir is read-only (done in permission())
|
|
* 2. We should have write and exec permissions on dir
|
|
* 3. We can't remove anything from append-only dir
|
|
* 4. We can't do anything with immutable dir (done in permission())
|
|
* 5. If the sticky bit on dir is set we should either
|
|
* a. be owner of dir, or
|
|
* b. be owner of victim, or
|
|
* c. have CAP_FOWNER capability
|
|
* 6. If the victim is append-only or immutable we can't do antyhing with
|
|
* links pointing to it.
|
|
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
|
|
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
|
|
* 9. We can't remove a root or mountpoint.
|
|
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
|
|
* nfs_async_unlink().
|
|
*/
|
|
static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
|
|
{
|
|
struct inode *inode = victim->d_inode;
|
|
int error;
|
|
|
|
if (d_is_negative(victim))
|
|
return -ENOENT;
|
|
BUG_ON(!inode);
|
|
|
|
BUG_ON(victim->d_parent->d_inode != dir);
|
|
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
|
|
|
|
error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
return error;
|
|
if (IS_APPEND(dir))
|
|
return -EPERM;
|
|
|
|
if (check_sticky(dir, inode) || IS_APPEND(inode) ||
|
|
IS_IMMUTABLE(inode) || IS_SWAPFILE(inode))
|
|
return -EPERM;
|
|
if (isdir) {
|
|
if (!d_is_directory(victim) && !d_is_autodir(victim))
|
|
return -ENOTDIR;
|
|
if (IS_ROOT(victim))
|
|
return -EBUSY;
|
|
} else if (d_is_directory(victim) || d_is_autodir(victim))
|
|
return -EISDIR;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
|
|
return -EBUSY;
|
|
return 0;
|
|
}
|
|
|
|
/* Check whether we can create an object with dentry child in directory
|
|
* dir.
|
|
* 1. We can't do it if child already exists (open has special treatment for
|
|
* this case, but since we are inlined it's OK)
|
|
* 2. We can't do it if dir is read-only (done in permission())
|
|
* 3. We should have write and exec permissions on dir
|
|
* 4. We can't do it if dir is immutable (done in permission())
|
|
*/
|
|
static inline int may_create(struct inode *dir, struct dentry *child)
|
|
{
|
|
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
|
|
if (child->d_inode)
|
|
return -EEXIST;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
return inode_permission(dir, MAY_WRITE | MAY_EXEC);
|
|
}
|
|
|
|
/*
|
|
* p1 and p2 should be directories on the same fs.
|
|
*/
|
|
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
struct dentry *p;
|
|
|
|
if (p1 == p2) {
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
return NULL;
|
|
}
|
|
|
|
mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
|
|
|
|
p = d_ancestor(p2, p1);
|
|
if (p) {
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
p = d_ancestor(p1, p2);
|
|
if (p) {
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return NULL;
|
|
}
|
|
|
|
void unlock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
mutex_unlock(&p1->d_inode->i_mutex);
|
|
if (p1 != p2) {
|
|
mutex_unlock(&p2->d_inode->i_mutex);
|
|
mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
|
|
}
|
|
}
|
|
|
|
int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
bool want_excl)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->create)
|
|
return -EACCES; /* shouldn't it be ENOSYS? */
|
|
mode &= S_IALLUGO;
|
|
mode |= S_IFREG;
|
|
error = security_inode_create(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
error = dir->i_op->create(dir, dentry, mode, want_excl);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
static int may_open(struct path *path, int acc_mode, int flag)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
struct inode *inode = dentry->d_inode;
|
|
int error;
|
|
|
|
/* O_PATH? */
|
|
if (!acc_mode)
|
|
return 0;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
switch (inode->i_mode & S_IFMT) {
|
|
case S_IFLNK:
|
|
return -ELOOP;
|
|
case S_IFDIR:
|
|
if (acc_mode & MAY_WRITE)
|
|
return -EISDIR;
|
|
break;
|
|
case S_IFBLK:
|
|
case S_IFCHR:
|
|
if (path->mnt->mnt_flags & MNT_NODEV)
|
|
return -EACCES;
|
|
/*FALLTHRU*/
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
flag &= ~O_TRUNC;
|
|
break;
|
|
}
|
|
|
|
error = inode_permission(inode, acc_mode);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* An append-only file must be opened in append mode for writing.
|
|
*/
|
|
if (IS_APPEND(inode)) {
|
|
if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
|
|
return -EPERM;
|
|
if (flag & O_TRUNC)
|
|
return -EPERM;
|
|
}
|
|
|
|
/* O_NOATIME can only be set by the owner or superuser */
|
|
if (flag & O_NOATIME && !inode_owner_or_capable(inode))
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int handle_truncate(struct file *filp)
|
|
{
|
|
struct path *path = &filp->f_path;
|
|
struct inode *inode = path->dentry->d_inode;
|
|
int error = get_write_access(inode);
|
|
if (error)
|
|
return error;
|
|
/*
|
|
* Refuse to truncate files with mandatory locks held on them.
|
|
*/
|
|
error = locks_verify_locked(inode);
|
|
if (!error)
|
|
error = security_path_truncate(path);
|
|
if (!error) {
|
|
error = do_truncate(path->dentry, 0,
|
|
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
|
|
filp);
|
|
}
|
|
put_write_access(inode);
|
|
return error;
|
|
}
|
|
|
|
static inline int open_to_namei_flags(int flag)
|
|
{
|
|
if ((flag & O_ACCMODE) == 3)
|
|
flag--;
|
|
return flag;
|
|
}
|
|
|
|
static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode)
|
|
{
|
|
int error = security_path_mknod(dir, dentry, mode, 0);
|
|
if (error)
|
|
return error;
|
|
|
|
error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
return error;
|
|
|
|
return security_inode_create(dir->dentry->d_inode, dentry, mode);
|
|
}
|
|
|
|
/*
|
|
* Attempt to atomically look up, create and open a file from a negative
|
|
* dentry.
|
|
*
|
|
* Returns 0 if successful. The file will have been created and attached to
|
|
* @file by the filesystem calling finish_open().
|
|
*
|
|
* Returns 1 if the file was looked up only or didn't need creating. The
|
|
* caller will need to perform the open themselves. @path will have been
|
|
* updated to point to the new dentry. This may be negative.
|
|
*
|
|
* Returns an error code otherwise.
|
|
*/
|
|
static int atomic_open(struct nameidata *nd, struct dentry *dentry,
|
|
struct path *path, struct file *file,
|
|
const struct open_flags *op,
|
|
bool got_write, bool need_lookup,
|
|
int *opened)
|
|
{
|
|
struct inode *dir = nd->path.dentry->d_inode;
|
|
unsigned open_flag = open_to_namei_flags(op->open_flag);
|
|
umode_t mode;
|
|
int error;
|
|
int acc_mode;
|
|
int create_error = 0;
|
|
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
|
|
bool excl;
|
|
|
|
BUG_ON(dentry->d_inode);
|
|
|
|
/* Don't create child dentry for a dead directory. */
|
|
if (unlikely(IS_DEADDIR(dir))) {
|
|
error = -ENOENT;
|
|
goto out;
|
|
}
|
|
|
|
mode = op->mode;
|
|
if ((open_flag & O_CREAT) && !IS_POSIXACL(dir))
|
|
mode &= ~current_umask();
|
|
|
|
excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT);
|
|
if (excl)
|
|
open_flag &= ~O_TRUNC;
|
|
|
|
/*
|
|
* Checking write permission is tricky, bacuse we don't know if we are
|
|
* going to actually need it: O_CREAT opens should work as long as the
|
|
* file exists. But checking existence breaks atomicity. The trick is
|
|
* to check access and if not granted clear O_CREAT from the flags.
|
|
*
|
|
* Another problem is returing the "right" error value (e.g. for an
|
|
* O_EXCL open we want to return EEXIST not EROFS).
|
|
*/
|
|
if (((open_flag & (O_CREAT | O_TRUNC)) ||
|
|
(open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) {
|
|
if (!(open_flag & O_CREAT)) {
|
|
/*
|
|
* No O_CREATE -> atomicity not a requirement -> fall
|
|
* back to lookup + open
|
|
*/
|
|
goto no_open;
|
|
} else if (open_flag & (O_EXCL | O_TRUNC)) {
|
|
/* Fall back and fail with the right error */
|
|
create_error = -EROFS;
|
|
goto no_open;
|
|
} else {
|
|
/* No side effects, safe to clear O_CREAT */
|
|
create_error = -EROFS;
|
|
open_flag &= ~O_CREAT;
|
|
}
|
|
}
|
|
|
|
if (open_flag & O_CREAT) {
|
|
error = may_o_create(&nd->path, dentry, mode);
|
|
if (error) {
|
|
create_error = error;
|
|
if (open_flag & O_EXCL)
|
|
goto no_open;
|
|
open_flag &= ~O_CREAT;
|
|
}
|
|
}
|
|
|
|
if (nd->flags & LOOKUP_DIRECTORY)
|
|
open_flag |= O_DIRECTORY;
|
|
|
|
file->f_path.dentry = DENTRY_NOT_SET;
|
|
file->f_path.mnt = nd->path.mnt;
|
|
error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode,
|
|
opened);
|
|
if (error < 0) {
|
|
if (create_error && error == -ENOENT)
|
|
error = create_error;
|
|
goto out;
|
|
}
|
|
|
|
if (error) { /* returned 1, that is */
|
|
if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
|
|
error = -EIO;
|
|
goto out;
|
|
}
|
|
if (file->f_path.dentry) {
|
|
dput(dentry);
|
|
dentry = file->f_path.dentry;
|
|
}
|
|
if (*opened & FILE_CREATED)
|
|
fsnotify_create(dir, dentry);
|
|
if (!dentry->d_inode) {
|
|
WARN_ON(*opened & FILE_CREATED);
|
|
if (create_error) {
|
|
error = create_error;
|
|
goto out;
|
|
}
|
|
} else {
|
|
if (excl && !(*opened & FILE_CREATED)) {
|
|
error = -EEXIST;
|
|
goto out;
|
|
}
|
|
}
|
|
goto looked_up;
|
|
}
|
|
|
|
/*
|
|
* We didn't have the inode before the open, so check open permission
|
|
* here.
|
|
*/
|
|
acc_mode = op->acc_mode;
|
|
if (*opened & FILE_CREATED) {
|
|
WARN_ON(!(open_flag & O_CREAT));
|
|
fsnotify_create(dir, dentry);
|
|
acc_mode = MAY_OPEN;
|
|
}
|
|
error = may_open(&file->f_path, acc_mode, open_flag);
|
|
if (error)
|
|
fput(file);
|
|
|
|
out:
|
|
dput(dentry);
|
|
return error;
|
|
|
|
no_open:
|
|
if (need_lookup) {
|
|
dentry = lookup_real(dir, dentry, nd->flags);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
if (create_error) {
|
|
int open_flag = op->open_flag;
|
|
|
|
error = create_error;
|
|
if ((open_flag & O_EXCL)) {
|
|
if (!dentry->d_inode)
|
|
goto out;
|
|
} else if (!dentry->d_inode) {
|
|
goto out;
|
|
} else if ((open_flag & O_TRUNC) &&
|
|
S_ISREG(dentry->d_inode->i_mode)) {
|
|
goto out;
|
|
}
|
|
/* will fail later, go on to get the right error */
|
|
}
|
|
}
|
|
looked_up:
|
|
path->dentry = dentry;
|
|
path->mnt = nd->path.mnt;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Look up and maybe create and open the last component.
|
|
*
|
|
* Must be called with i_mutex held on parent.
|
|
*
|
|
* Returns 0 if the file was successfully atomically created (if necessary) and
|
|
* opened. In this case the file will be returned attached to @file.
|
|
*
|
|
* Returns 1 if the file was not completely opened at this time, though lookups
|
|
* and creations will have been performed and the dentry returned in @path will
|
|
* be positive upon return if O_CREAT was specified. If O_CREAT wasn't
|
|
* specified then a negative dentry may be returned.
|
|
*
|
|
* An error code is returned otherwise.
|
|
*
|
|
* FILE_CREATE will be set in @*opened if the dentry was created and will be
|
|
* cleared otherwise prior to returning.
|
|
*/
|
|
static int lookup_open(struct nameidata *nd, struct path *path,
|
|
struct file *file,
|
|
const struct open_flags *op,
|
|
bool got_write, int *opened)
|
|
{
|
|
struct dentry *dir = nd->path.dentry;
|
|
struct inode *dir_inode = dir->d_inode;
|
|
struct dentry *dentry;
|
|
int error;
|
|
bool need_lookup;
|
|
|
|
*opened &= ~FILE_CREATED;
|
|
dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
/* Cached positive dentry: will open in f_op->open */
|
|
if (!need_lookup && dentry->d_inode)
|
|
goto out_no_open;
|
|
|
|
if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) {
|
|
return atomic_open(nd, dentry, path, file, op, got_write,
|
|
need_lookup, opened);
|
|
}
|
|
|
|
if (need_lookup) {
|
|
BUG_ON(dentry->d_inode);
|
|
|
|
dentry = lookup_real(dir_inode, dentry, nd->flags);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
}
|
|
|
|
/* Negative dentry, just create the file */
|
|
if (!dentry->d_inode && (op->open_flag & O_CREAT)) {
|
|
umode_t mode = op->mode;
|
|
if (!IS_POSIXACL(dir->d_inode))
|
|
mode &= ~current_umask();
|
|
/*
|
|
* This write is needed to ensure that a
|
|
* rw->ro transition does not occur between
|
|
* the time when the file is created and when
|
|
* a permanent write count is taken through
|
|
* the 'struct file' in finish_open().
|
|
*/
|
|
if (!got_write) {
|
|
error = -EROFS;
|
|
goto out_dput;
|
|
}
|
|
*opened |= FILE_CREATED;
|
|
error = security_path_mknod(&nd->path, dentry, mode, 0);
|
|
if (error)
|
|
goto out_dput;
|
|
error = vfs_create(dir->d_inode, dentry, mode,
|
|
nd->flags & LOOKUP_EXCL);
|
|
if (error)
|
|
goto out_dput;
|
|
}
|
|
out_no_open:
|
|
path->dentry = dentry;
|
|
path->mnt = nd->path.mnt;
|
|
return 1;
|
|
|
|
out_dput:
|
|
dput(dentry);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Handle the last step of open()
|
|
*/
|
|
static int do_last(struct nameidata *nd, struct path *path,
|
|
struct file *file, const struct open_flags *op,
|
|
int *opened, struct filename *name)
|
|
{
|
|
struct dentry *dir = nd->path.dentry;
|
|
int open_flag = op->open_flag;
|
|
bool will_truncate = (open_flag & O_TRUNC) != 0;
|
|
bool got_write = false;
|
|
int acc_mode = op->acc_mode;
|
|
struct inode *inode;
|
|
bool symlink_ok = false;
|
|
struct path save_parent = { .dentry = NULL, .mnt = NULL };
|
|
bool retried = false;
|
|
int error;
|
|
|
|
nd->flags &= ~LOOKUP_PARENT;
|
|
nd->flags |= op->intent;
|
|
|
|
if (nd->last_type != LAST_NORM) {
|
|
error = handle_dots(nd, nd->last_type);
|
|
if (error)
|
|
return error;
|
|
goto finish_open;
|
|
}
|
|
|
|
if (!(open_flag & O_CREAT)) {
|
|
if (nd->last.name[nd->last.len])
|
|
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
|
|
symlink_ok = true;
|
|
/* we _can_ be in RCU mode here */
|
|
error = lookup_fast(nd, path, &inode);
|
|
if (likely(!error))
|
|
goto finish_lookup;
|
|
|
|
if (error < 0)
|
|
goto out;
|
|
|
|
BUG_ON(nd->inode != dir->d_inode);
|
|
} else {
|
|
/* create side of things */
|
|
/*
|
|
* This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
|
|
* has been cleared when we got to the last component we are
|
|
* about to look up
|
|
*/
|
|
error = complete_walk(nd);
|
|
if (error)
|
|
return error;
|
|
|
|
audit_inode(name, dir, LOOKUP_PARENT);
|
|
error = -EISDIR;
|
|
/* trailing slashes? */
|
|
if (nd->last.name[nd->last.len])
|
|
goto out;
|
|
}
|
|
|
|
retry_lookup:
|
|
if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
|
|
error = mnt_want_write(nd->path.mnt);
|
|
if (!error)
|
|
got_write = true;
|
|
/*
|
|
* do _not_ fail yet - we might not need that or fail with
|
|
* a different error; let lookup_open() decide; we'll be
|
|
* dropping this one anyway.
|
|
*/
|
|
}
|
|
mutex_lock(&dir->d_inode->i_mutex);
|
|
error = lookup_open(nd, path, file, op, got_write, opened);
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
|
|
if (error <= 0) {
|
|
if (error)
|
|
goto out;
|
|
|
|
if ((*opened & FILE_CREATED) ||
|
|
!S_ISREG(file_inode(file)->i_mode))
|
|
will_truncate = false;
|
|
|
|
audit_inode(name, file->f_path.dentry, 0);
|
|
goto opened;
|
|
}
|
|
|
|
if (*opened & FILE_CREATED) {
|
|
/* Don't check for write permission, don't truncate */
|
|
open_flag &= ~O_TRUNC;
|
|
will_truncate = false;
|
|
acc_mode = MAY_OPEN;
|
|
path_to_nameidata(path, nd);
|
|
goto finish_open_created;
|
|
}
|
|
|
|
/*
|
|
* create/update audit record if it already exists.
|
|
*/
|
|
if (d_is_positive(path->dentry))
|
|
audit_inode(name, path->dentry, 0);
|
|
|
|
/*
|
|
* If atomic_open() acquired write access it is dropped now due to
|
|
* possible mount and symlink following (this might be optimized away if
|
|
* necessary...)
|
|
*/
|
|
if (got_write) {
|
|
mnt_drop_write(nd->path.mnt);
|
|
got_write = false;
|
|
}
|
|
|
|
error = -EEXIST;
|
|
if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))
|
|
goto exit_dput;
|
|
|
|
error = follow_managed(path, nd->flags);
|
|
if (error < 0)
|
|
goto exit_dput;
|
|
|
|
if (error)
|
|
nd->flags |= LOOKUP_JUMPED;
|
|
|
|
BUG_ON(nd->flags & LOOKUP_RCU);
|
|
inode = path->dentry->d_inode;
|
|
finish_lookup:
|
|
/* we _can_ be in RCU mode here */
|
|
error = -ENOENT;
|
|
if (d_is_negative(path->dentry)) {
|
|
path_to_nameidata(path, nd);
|
|
goto out;
|
|
}
|
|
|
|
if (should_follow_link(path->dentry, !symlink_ok)) {
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (unlikely(unlazy_walk(nd, path->dentry))) {
|
|
error = -ECHILD;
|
|
goto out;
|
|
}
|
|
}
|
|
BUG_ON(inode != path->dentry->d_inode);
|
|
return 1;
|
|
}
|
|
|
|
if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) {
|
|
path_to_nameidata(path, nd);
|
|
} else {
|
|
save_parent.dentry = nd->path.dentry;
|
|
save_parent.mnt = mntget(path->mnt);
|
|
nd->path.dentry = path->dentry;
|
|
|
|
}
|
|
nd->inode = inode;
|
|
/* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
|
|
finish_open:
|
|
error = complete_walk(nd);
|
|
if (error) {
|
|
path_put(&save_parent);
|
|
return error;
|
|
}
|
|
audit_inode(name, nd->path.dentry, 0);
|
|
error = -EISDIR;
|
|
if ((open_flag & O_CREAT) &&
|
|
(d_is_directory(nd->path.dentry) || d_is_autodir(nd->path.dentry)))
|
|
goto out;
|
|
error = -ENOTDIR;
|
|
if ((nd->flags & LOOKUP_DIRECTORY) && !d_is_directory(nd->path.dentry))
|
|
goto out;
|
|
if (!S_ISREG(nd->inode->i_mode))
|
|
will_truncate = false;
|
|
|
|
if (will_truncate) {
|
|
error = mnt_want_write(nd->path.mnt);
|
|
if (error)
|
|
goto out;
|
|
got_write = true;
|
|
}
|
|
finish_open_created:
|
|
error = may_open(&nd->path, acc_mode, open_flag);
|
|
if (error)
|
|
goto out;
|
|
file->f_path.mnt = nd->path.mnt;
|
|
error = finish_open(file, nd->path.dentry, NULL, opened);
|
|
if (error) {
|
|
if (error == -EOPENSTALE)
|
|
goto stale_open;
|
|
goto out;
|
|
}
|
|
opened:
|
|
error = open_check_o_direct(file);
|
|
if (error)
|
|
goto exit_fput;
|
|
error = ima_file_check(file, op->acc_mode);
|
|
if (error)
|
|
goto exit_fput;
|
|
|
|
if (will_truncate) {
|
|
error = handle_truncate(file);
|
|
if (error)
|
|
goto exit_fput;
|
|
}
|
|
out:
|
|
if (got_write)
|
|
mnt_drop_write(nd->path.mnt);
|
|
path_put(&save_parent);
|
|
terminate_walk(nd);
|
|
return error;
|
|
|
|
exit_dput:
|
|
path_put_conditional(path, nd);
|
|
goto out;
|
|
exit_fput:
|
|
fput(file);
|
|
goto out;
|
|
|
|
stale_open:
|
|
/* If no saved parent or already retried then can't retry */
|
|
if (!save_parent.dentry || retried)
|
|
goto out;
|
|
|
|
BUG_ON(save_parent.dentry != dir);
|
|
path_put(&nd->path);
|
|
nd->path = save_parent;
|
|
nd->inode = dir->d_inode;
|
|
save_parent.mnt = NULL;
|
|
save_parent.dentry = NULL;
|
|
if (got_write) {
|
|
mnt_drop_write(nd->path.mnt);
|
|
got_write = false;
|
|
}
|
|
retried = true;
|
|
goto retry_lookup;
|
|
}
|
|
|
|
static int do_tmpfile(int dfd, struct filename *pathname,
|
|
struct nameidata *nd, int flags,
|
|
const struct open_flags *op,
|
|
struct file *file, int *opened)
|
|
{
|
|
static const struct qstr name = QSTR_INIT("/", 1);
|
|
struct dentry *dentry, *child;
|
|
struct inode *dir;
|
|
int error = path_lookupat(dfd, pathname->name,
|
|
flags | LOOKUP_DIRECTORY, nd);
|
|
if (unlikely(error))
|
|
return error;
|
|
error = mnt_want_write(nd->path.mnt);
|
|
if (unlikely(error))
|
|
goto out;
|
|
/* we want directory to be writable */
|
|
error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
goto out2;
|
|
dentry = nd->path.dentry;
|
|
dir = dentry->d_inode;
|
|
if (!dir->i_op->tmpfile) {
|
|
error = -EOPNOTSUPP;
|
|
goto out2;
|
|
}
|
|
child = d_alloc(dentry, &name);
|
|
if (unlikely(!child)) {
|
|
error = -ENOMEM;
|
|
goto out2;
|
|
}
|
|
nd->flags &= ~LOOKUP_DIRECTORY;
|
|
nd->flags |= op->intent;
|
|
dput(nd->path.dentry);
|
|
nd->path.dentry = child;
|
|
error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode);
|
|
if (error)
|
|
goto out2;
|
|
audit_inode(pathname, nd->path.dentry, 0);
|
|
error = may_open(&nd->path, op->acc_mode, op->open_flag);
|
|
if (error)
|
|
goto out2;
|
|
file->f_path.mnt = nd->path.mnt;
|
|
error = finish_open(file, nd->path.dentry, NULL, opened);
|
|
if (error)
|
|
goto out2;
|
|
error = open_check_o_direct(file);
|
|
if (error) {
|
|
fput(file);
|
|
} else if (!(op->open_flag & O_EXCL)) {
|
|
struct inode *inode = file_inode(file);
|
|
spin_lock(&inode->i_lock);
|
|
inode->i_state |= I_LINKABLE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
out2:
|
|
mnt_drop_write(nd->path.mnt);
|
|
out:
|
|
path_put(&nd->path);
|
|
return error;
|
|
}
|
|
|
|
static struct file *path_openat(int dfd, struct filename *pathname,
|
|
struct nameidata *nd, const struct open_flags *op, int flags)
|
|
{
|
|
struct file *base = NULL;
|
|
struct file *file;
|
|
struct path path;
|
|
int opened = 0;
|
|
int error;
|
|
|
|
file = get_empty_filp();
|
|
if (IS_ERR(file))
|
|
return file;
|
|
|
|
file->f_flags = op->open_flag;
|
|
|
|
if (unlikely(file->f_flags & __O_TMPFILE)) {
|
|
error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened);
|
|
goto out;
|
|
}
|
|
|
|
error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base);
|
|
if (unlikely(error))
|
|
goto out;
|
|
|
|
current->total_link_count = 0;
|
|
error = link_path_walk(pathname->name, nd);
|
|
if (unlikely(error))
|
|
goto out;
|
|
|
|
error = do_last(nd, &path, file, op, &opened, pathname);
|
|
while (unlikely(error > 0)) { /* trailing symlink */
|
|
struct path link = path;
|
|
void *cookie;
|
|
if (!(nd->flags & LOOKUP_FOLLOW)) {
|
|
path_put_conditional(&path, nd);
|
|
path_put(&nd->path);
|
|
error = -ELOOP;
|
|
break;
|
|
}
|
|
error = may_follow_link(&link, nd);
|
|
if (unlikely(error))
|
|
break;
|
|
nd->flags |= LOOKUP_PARENT;
|
|
nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
|
|
error = follow_link(&link, nd, &cookie);
|
|
if (unlikely(error))
|
|
break;
|
|
error = do_last(nd, &path, file, op, &opened, pathname);
|
|
put_link(nd, &link, cookie);
|
|
}
|
|
out:
|
|
if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
|
|
path_put(&nd->root);
|
|
if (base)
|
|
fput(base);
|
|
if (!(opened & FILE_OPENED)) {
|
|
BUG_ON(!error);
|
|
put_filp(file);
|
|
}
|
|
if (unlikely(error)) {
|
|
if (error == -EOPENSTALE) {
|
|
if (flags & LOOKUP_RCU)
|
|
error = -ECHILD;
|
|
else
|
|
error = -ESTALE;
|
|
}
|
|
file = ERR_PTR(error);
|
|
}
|
|
return file;
|
|
}
|
|
|
|
struct file *do_filp_open(int dfd, struct filename *pathname,
|
|
const struct open_flags *op)
|
|
{
|
|
struct nameidata nd;
|
|
int flags = op->lookup_flags;
|
|
struct file *filp;
|
|
|
|
filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
|
|
if (unlikely(filp == ERR_PTR(-ECHILD)))
|
|
filp = path_openat(dfd, pathname, &nd, op, flags);
|
|
if (unlikely(filp == ERR_PTR(-ESTALE)))
|
|
filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
|
|
return filp;
|
|
}
|
|
|
|
struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *name, const struct open_flags *op)
|
|
{
|
|
struct nameidata nd;
|
|
struct file *file;
|
|
struct filename filename = { .name = name };
|
|
int flags = op->lookup_flags | LOOKUP_ROOT;
|
|
|
|
nd.root.mnt = mnt;
|
|
nd.root.dentry = dentry;
|
|
|
|
if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
|
|
return ERR_PTR(-ELOOP);
|
|
|
|
file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU);
|
|
if (unlikely(file == ERR_PTR(-ECHILD)))
|
|
file = path_openat(-1, &filename, &nd, op, flags);
|
|
if (unlikely(file == ERR_PTR(-ESTALE)))
|
|
file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL);
|
|
return file;
|
|
}
|
|
|
|
struct dentry *kern_path_create(int dfd, const char *pathname,
|
|
struct path *path, unsigned int lookup_flags)
|
|
{
|
|
struct dentry *dentry = ERR_PTR(-EEXIST);
|
|
struct nameidata nd;
|
|
int err2;
|
|
int error;
|
|
bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
|
|
|
|
/*
|
|
* Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
|
|
* other flags passed in are ignored!
|
|
*/
|
|
lookup_flags &= LOOKUP_REVAL;
|
|
|
|
error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
|
|
/*
|
|
* Yucky last component or no last component at all?
|
|
* (foo/., foo/.., /////)
|
|
*/
|
|
if (nd.last_type != LAST_NORM)
|
|
goto out;
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
|
|
|
|
/* don't fail immediately if it's r/o, at least try to report other errors */
|
|
err2 = mnt_want_write(nd.path.mnt);
|
|
/*
|
|
* Do the final lookup.
|
|
*/
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
dentry = lookup_hash(&nd);
|
|
if (IS_ERR(dentry))
|
|
goto unlock;
|
|
|
|
error = -EEXIST;
|
|
if (d_is_positive(dentry))
|
|
goto fail;
|
|
|
|
/*
|
|
* Special case - lookup gave negative, but... we had foo/bar/
|
|
* From the vfs_mknod() POV we just have a negative dentry -
|
|
* all is fine. Let's be bastards - you had / on the end, you've
|
|
* been asking for (non-existent) directory. -ENOENT for you.
|
|
*/
|
|
if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
|
|
error = -ENOENT;
|
|
goto fail;
|
|
}
|
|
if (unlikely(err2)) {
|
|
error = err2;
|
|
goto fail;
|
|
}
|
|
*path = nd.path;
|
|
return dentry;
|
|
fail:
|
|
dput(dentry);
|
|
dentry = ERR_PTR(error);
|
|
unlock:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
if (!err2)
|
|
mnt_drop_write(nd.path.mnt);
|
|
out:
|
|
path_put(&nd.path);
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL(kern_path_create);
|
|
|
|
void done_path_create(struct path *path, struct dentry *dentry)
|
|
{
|
|
dput(dentry);
|
|
mutex_unlock(&path->dentry->d_inode->i_mutex);
|
|
mnt_drop_write(path->mnt);
|
|
path_put(path);
|
|
}
|
|
EXPORT_SYMBOL(done_path_create);
|
|
|
|
struct dentry *user_path_create(int dfd, const char __user *pathname,
|
|
struct path *path, unsigned int lookup_flags)
|
|
{
|
|
struct filename *tmp = getname(pathname);
|
|
struct dentry *res;
|
|
if (IS_ERR(tmp))
|
|
return ERR_CAST(tmp);
|
|
res = kern_path_create(dfd, tmp->name, path, lookup_flags);
|
|
putname(tmp);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(user_path_create);
|
|
|
|
int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
|
|
return -EPERM;
|
|
|
|
if (!dir->i_op->mknod)
|
|
return -EPERM;
|
|
|
|
error = devcgroup_inode_mknod(mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
error = security_inode_mknod(dir, dentry, mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
error = dir->i_op->mknod(dir, dentry, mode, dev);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
static int may_mknod(umode_t mode)
|
|
{
|
|
switch (mode & S_IFMT) {
|
|
case S_IFREG:
|
|
case S_IFCHR:
|
|
case S_IFBLK:
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
case 0: /* zero mode translates to S_IFREG */
|
|
return 0;
|
|
case S_IFDIR:
|
|
return -EPERM;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
|
|
unsigned, dev)
|
|
{
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = 0;
|
|
|
|
error = may_mknod(mode);
|
|
if (error)
|
|
return error;
|
|
retry:
|
|
dentry = user_path_create(dfd, filename, &path, lookup_flags);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
if (!IS_POSIXACL(path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = security_path_mknod(&path, dentry, mode, dev);
|
|
if (error)
|
|
goto out;
|
|
switch (mode & S_IFMT) {
|
|
case 0: case S_IFREG:
|
|
error = vfs_create(path.dentry->d_inode,dentry,mode,true);
|
|
break;
|
|
case S_IFCHR: case S_IFBLK:
|
|
error = vfs_mknod(path.dentry->d_inode,dentry,mode,
|
|
new_decode_dev(dev));
|
|
break;
|
|
case S_IFIFO: case S_IFSOCK:
|
|
error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
|
|
break;
|
|
}
|
|
out:
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
|
|
{
|
|
return sys_mknodat(AT_FDCWD, filename, mode, dev);
|
|
}
|
|
|
|
int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
unsigned max_links = dir->i_sb->s_max_links;
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->mkdir)
|
|
return -EPERM;
|
|
|
|
mode &= (S_IRWXUGO|S_ISVTX);
|
|
error = security_inode_mkdir(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
|
|
if (max_links && dir->i_nlink >= max_links)
|
|
return -EMLINK;
|
|
|
|
error = dir->i_op->mkdir(dir, dentry, mode);
|
|
if (!error)
|
|
fsnotify_mkdir(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_DIRECTORY;
|
|
|
|
retry:
|
|
dentry = user_path_create(dfd, pathname, &path, lookup_flags);
|
|
if (IS_ERR(dentry))
|
|
return PTR_ERR(dentry);
|
|
|
|
if (!IS_POSIXACL(path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = security_path_mkdir(&path, dentry, mode);
|
|
if (!error)
|
|
error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
return sys_mkdirat(AT_FDCWD, pathname, mode);
|
|
}
|
|
|
|
/*
|
|
* The dentry_unhash() helper will try to drop the dentry early: we
|
|
* should have a usage count of 1 if we're the only user of this
|
|
* dentry, and if that is true (possibly after pruning the dcache),
|
|
* then we drop the dentry now.
|
|
*
|
|
* A low-level filesystem can, if it choses, legally
|
|
* do a
|
|
*
|
|
* if (!d_unhashed(dentry))
|
|
* return -EBUSY;
|
|
*
|
|
* if it cannot handle the case of removing a directory
|
|
* that is still in use by something else..
|
|
*/
|
|
void dentry_unhash(struct dentry *dentry)
|
|
{
|
|
shrink_dcache_parent(dentry);
|
|
spin_lock(&dentry->d_lock);
|
|
if (dentry->d_lockref.count == 1)
|
|
__d_drop(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
|
|
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
int error = may_delete(dir, dentry, 1);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->rmdir)
|
|
return -EPERM;
|
|
|
|
dget(dentry);
|
|
mutex_lock(&dentry->d_inode->i_mutex);
|
|
|
|
error = -EBUSY;
|
|
if (d_mountpoint(dentry))
|
|
goto out;
|
|
|
|
error = security_inode_rmdir(dir, dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
shrink_dcache_parent(dentry);
|
|
error = dir->i_op->rmdir(dir, dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
dentry->d_inode->i_flags |= S_DEAD;
|
|
dont_mount(dentry);
|
|
|
|
out:
|
|
mutex_unlock(&dentry->d_inode->i_mutex);
|
|
dput(dentry);
|
|
if (!error)
|
|
d_delete(dentry);
|
|
return error;
|
|
}
|
|
|
|
static long do_rmdir(int dfd, const char __user *pathname)
|
|
{
|
|
int error = 0;
|
|
struct filename *name;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
unsigned int lookup_flags = 0;
|
|
retry:
|
|
name = user_path_parent(dfd, pathname, &nd, lookup_flags);
|
|
if (IS_ERR(name))
|
|
return PTR_ERR(name);
|
|
|
|
switch(nd.last_type) {
|
|
case LAST_DOTDOT:
|
|
error = -ENOTEMPTY;
|
|
goto exit1;
|
|
case LAST_DOT:
|
|
error = -EINVAL;
|
|
goto exit1;
|
|
case LAST_ROOT:
|
|
error = -EBUSY;
|
|
goto exit1;
|
|
}
|
|
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit1;
|
|
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
dentry = lookup_hash(&nd);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto exit2;
|
|
if (!dentry->d_inode) {
|
|
error = -ENOENT;
|
|
goto exit3;
|
|
}
|
|
error = security_path_rmdir(&nd.path, dentry);
|
|
if (error)
|
|
goto exit3;
|
|
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
|
|
exit3:
|
|
dput(dentry);
|
|
exit2:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
mnt_drop_write(nd.path.mnt);
|
|
exit1:
|
|
path_put(&nd.path);
|
|
putname(name);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
|
|
{
|
|
return do_rmdir(AT_FDCWD, pathname);
|
|
}
|
|
|
|
/**
|
|
* vfs_unlink - unlink a filesystem object
|
|
* @dir: parent directory
|
|
* @dentry: victim
|
|
* @delegated_inode: returns victim inode, if the inode is delegated.
|
|
*
|
|
* The caller must hold dir->i_mutex.
|
|
*
|
|
* If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
|
|
* return a reference to the inode in delegated_inode. The caller
|
|
* should then break the delegation on that inode and retry. Because
|
|
* breaking a delegation may take a long time, the caller should drop
|
|
* dir->i_mutex before doing so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*/
|
|
int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
|
|
{
|
|
struct inode *target = dentry->d_inode;
|
|
int error = may_delete(dir, dentry, 0);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->unlink)
|
|
return -EPERM;
|
|
|
|
mutex_lock(&target->i_mutex);
|
|
if (d_mountpoint(dentry))
|
|
error = -EBUSY;
|
|
else {
|
|
error = security_inode_unlink(dir, dentry);
|
|
if (!error) {
|
|
error = try_break_deleg(target, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
error = dir->i_op->unlink(dir, dentry);
|
|
if (!error)
|
|
dont_mount(dentry);
|
|
}
|
|
}
|
|
out:
|
|
mutex_unlock(&target->i_mutex);
|
|
|
|
/* We don't d_delete() NFS sillyrenamed files--they still exist. */
|
|
if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
|
|
fsnotify_link_count(target);
|
|
d_delete(dentry);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Make sure that the actual truncation of the file will occur outside its
|
|
* directory's i_mutex. Truncate can take a long time if there is a lot of
|
|
* writeout happening, and we don't want to prevent access to the directory
|
|
* while waiting on the I/O.
|
|
*/
|
|
static long do_unlinkat(int dfd, const char __user *pathname)
|
|
{
|
|
int error;
|
|
struct filename *name;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
struct inode *inode = NULL;
|
|
struct inode *delegated_inode = NULL;
|
|
unsigned int lookup_flags = 0;
|
|
retry:
|
|
name = user_path_parent(dfd, pathname, &nd, lookup_flags);
|
|
if (IS_ERR(name))
|
|
return PTR_ERR(name);
|
|
|
|
error = -EISDIR;
|
|
if (nd.last_type != LAST_NORM)
|
|
goto exit1;
|
|
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit1;
|
|
retry_deleg:
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
dentry = lookup_hash(&nd);
|
|
error = PTR_ERR(dentry);
|
|
if (!IS_ERR(dentry)) {
|
|
/* Why not before? Because we want correct error value */
|
|
if (nd.last.name[nd.last.len])
|
|
goto slashes;
|
|
inode = dentry->d_inode;
|
|
if (d_is_negative(dentry))
|
|
goto slashes;
|
|
ihold(inode);
|
|
error = security_path_unlink(&nd.path, dentry);
|
|
if (error)
|
|
goto exit2;
|
|
error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode);
|
|
exit2:
|
|
dput(dentry);
|
|
}
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
if (inode)
|
|
iput(inode); /* truncate the inode here */
|
|
inode = NULL;
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(nd.path.mnt);
|
|
exit1:
|
|
path_put(&nd.path);
|
|
putname(name);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
inode = NULL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
|
|
slashes:
|
|
if (d_is_negative(dentry))
|
|
error = -ENOENT;
|
|
else if (d_is_directory(dentry) || d_is_autodir(dentry))
|
|
error = -EISDIR;
|
|
else
|
|
error = -ENOTDIR;
|
|
goto exit2;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
|
|
{
|
|
if ((flag & ~AT_REMOVEDIR) != 0)
|
|
return -EINVAL;
|
|
|
|
if (flag & AT_REMOVEDIR)
|
|
return do_rmdir(dfd, pathname);
|
|
|
|
return do_unlinkat(dfd, pathname);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(unlink, const char __user *, pathname)
|
|
{
|
|
return do_unlinkat(AT_FDCWD, pathname);
|
|
}
|
|
|
|
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->symlink)
|
|
return -EPERM;
|
|
|
|
error = security_inode_symlink(dir, dentry, oldname);
|
|
if (error)
|
|
return error;
|
|
|
|
error = dir->i_op->symlink(dir, dentry, oldname);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
int error;
|
|
struct filename *from;
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
unsigned int lookup_flags = 0;
|
|
|
|
from = getname(oldname);
|
|
if (IS_ERR(from))
|
|
return PTR_ERR(from);
|
|
retry:
|
|
dentry = user_path_create(newdfd, newname, &path, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out_putname;
|
|
|
|
error = security_path_symlink(&path, dentry, from->name);
|
|
if (!error)
|
|
error = vfs_symlink(path.dentry->d_inode, dentry, from->name);
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out_putname:
|
|
putname(from);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_symlinkat(oldname, AT_FDCWD, newname);
|
|
}
|
|
|
|
/**
|
|
* vfs_link - create a new link
|
|
* @old_dentry: object to be linked
|
|
* @dir: new parent
|
|
* @new_dentry: where to create the new link
|
|
* @delegated_inode: returns inode needing a delegation break
|
|
*
|
|
* The caller must hold dir->i_mutex
|
|
*
|
|
* If vfs_link discovers a delegation on the to-be-linked file in need
|
|
* of breaking, it will return -EWOULDBLOCK and return a reference to the
|
|
* inode in delegated_inode. The caller should then break the delegation
|
|
* and retry. Because breaking a delegation may take a long time, the
|
|
* caller should drop the i_mutex before doing so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*/
|
|
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
|
|
{
|
|
struct inode *inode = old_dentry->d_inode;
|
|
unsigned max_links = dir->i_sb->s_max_links;
|
|
int error;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
error = may_create(dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (dir->i_sb != inode->i_sb)
|
|
return -EXDEV;
|
|
|
|
/*
|
|
* A link to an append-only or immutable file cannot be created.
|
|
*/
|
|
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
|
|
return -EPERM;
|
|
if (!dir->i_op->link)
|
|
return -EPERM;
|
|
if (S_ISDIR(inode->i_mode))
|
|
return -EPERM;
|
|
|
|
error = security_inode_link(old_dentry, dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
/* Make sure we don't allow creating hardlink to an unlinked file */
|
|
if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
|
|
error = -ENOENT;
|
|
else if (max_links && inode->i_nlink >= max_links)
|
|
error = -EMLINK;
|
|
else {
|
|
error = try_break_deleg(inode, delegated_inode);
|
|
if (!error)
|
|
error = dir->i_op->link(old_dentry, dir, new_dentry);
|
|
}
|
|
|
|
if (!error && (inode->i_state & I_LINKABLE)) {
|
|
spin_lock(&inode->i_lock);
|
|
inode->i_state &= ~I_LINKABLE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
mutex_unlock(&inode->i_mutex);
|
|
if (!error)
|
|
fsnotify_link(dir, inode, new_dentry);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Hardlinks are often used in delicate situations. We avoid
|
|
* security-related surprises by not following symlinks on the
|
|
* newname. --KAB
|
|
*
|
|
* We don't follow them on the oldname either to be compatible
|
|
* with linux 2.0, and to avoid hard-linking to directories
|
|
* and other special files. --ADM
|
|
*/
|
|
SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname, int, flags)
|
|
{
|
|
struct dentry *new_dentry;
|
|
struct path old_path, new_path;
|
|
struct inode *delegated_inode = NULL;
|
|
int how = 0;
|
|
int error;
|
|
|
|
if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
|
|
return -EINVAL;
|
|
/*
|
|
* To use null names we require CAP_DAC_READ_SEARCH
|
|
* This ensures that not everyone will be able to create
|
|
* handlink using the passed filedescriptor.
|
|
*/
|
|
if (flags & AT_EMPTY_PATH) {
|
|
if (!capable(CAP_DAC_READ_SEARCH))
|
|
return -ENOENT;
|
|
how = LOOKUP_EMPTY;
|
|
}
|
|
|
|
if (flags & AT_SYMLINK_FOLLOW)
|
|
how |= LOOKUP_FOLLOW;
|
|
retry:
|
|
error = user_path_at(olddfd, oldname, how, &old_path);
|
|
if (error)
|
|
return error;
|
|
|
|
new_dentry = user_path_create(newdfd, newname, &new_path,
|
|
(how & LOOKUP_REVAL));
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto out;
|
|
|
|
error = -EXDEV;
|
|
if (old_path.mnt != new_path.mnt)
|
|
goto out_dput;
|
|
error = may_linkat(&old_path);
|
|
if (unlikely(error))
|
|
goto out_dput;
|
|
error = security_path_link(old_path.dentry, &new_path, new_dentry);
|
|
if (error)
|
|
goto out_dput;
|
|
error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode);
|
|
out_dput:
|
|
done_path_create(&new_path, new_dentry);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry;
|
|
}
|
|
if (retry_estale(error, how)) {
|
|
how |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
path_put(&old_path);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
|
|
}
|
|
|
|
/*
|
|
* The worst of all namespace operations - renaming directory. "Perverted"
|
|
* doesn't even start to describe it. Somebody in UCB had a heck of a trip...
|
|
* Problems:
|
|
* a) we can get into loop creation. Check is done in is_subdir().
|
|
* b) race potential - two innocent renames can create a loop together.
|
|
* That's where 4.4 screws up. Current fix: serialization on
|
|
* sb->s_vfs_rename_mutex. We might be more accurate, but that's another
|
|
* story.
|
|
* c) we have to lock _four_ objects - parents and victim (if it exists),
|
|
* and source (if it is not a directory).
|
|
* And that - after we got ->i_mutex on parents (until then we don't know
|
|
* whether the target exists). Solution: try to be smart with locking
|
|
* order for inodes. We rely on the fact that tree topology may change
|
|
* only under ->s_vfs_rename_mutex _and_ that parent of the object we
|
|
* move will be locked. Thus we can rank directories by the tree
|
|
* (ancestors first) and rank all non-directories after them.
|
|
* That works since everybody except rename does "lock parent, lookup,
|
|
* lock child" and rename is under ->s_vfs_rename_mutex.
|
|
* HOWEVER, it relies on the assumption that any object with ->lookup()
|
|
* has no more than 1 dentry. If "hybrid" objects will ever appear,
|
|
* we'd better make sure that there's no link(2) for them.
|
|
* d) conversion from fhandle to dentry may come in the wrong moment - when
|
|
* we are removing the target. Solution: we will have to grab ->i_mutex
|
|
* in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
|
|
* ->i_mutex on parents, which works but leads to some truly excessive
|
|
* locking].
|
|
*/
|
|
static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
int error = 0;
|
|
struct inode *target = new_dentry->d_inode;
|
|
unsigned max_links = new_dir->i_sb->s_max_links;
|
|
|
|
/*
|
|
* If we are going to change the parent - check write permissions,
|
|
* we'll need to flip '..'.
|
|
*/
|
|
if (new_dir != old_dir) {
|
|
error = inode_permission(old_dentry->d_inode, MAY_WRITE);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
dget(new_dentry);
|
|
if (target)
|
|
mutex_lock(&target->i_mutex);
|
|
|
|
error = -EBUSY;
|
|
if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
|
|
goto out;
|
|
|
|
error = -EMLINK;
|
|
if (max_links && !target && new_dir != old_dir &&
|
|
new_dir->i_nlink >= max_links)
|
|
goto out;
|
|
|
|
if (target)
|
|
shrink_dcache_parent(new_dentry);
|
|
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
if (target) {
|
|
target->i_flags |= S_DEAD;
|
|
dont_mount(new_dentry);
|
|
}
|
|
out:
|
|
if (target)
|
|
mutex_unlock(&target->i_mutex);
|
|
dput(new_dentry);
|
|
if (!error)
|
|
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
|
|
d_move(old_dentry,new_dentry);
|
|
return error;
|
|
}
|
|
|
|
static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry,
|
|
struct inode **delegated_inode)
|
|
{
|
|
struct inode *target = new_dentry->d_inode;
|
|
struct inode *source = old_dentry->d_inode;
|
|
int error;
|
|
|
|
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
dget(new_dentry);
|
|
lock_two_nondirectories(source, target);
|
|
|
|
error = -EBUSY;
|
|
if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
|
|
goto out;
|
|
|
|
error = try_break_deleg(source, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
if (target) {
|
|
error = try_break_deleg(target, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
if (target)
|
|
dont_mount(new_dentry);
|
|
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
|
|
d_move(old_dentry, new_dentry);
|
|
out:
|
|
unlock_two_nondirectories(source, target);
|
|
dput(new_dentry);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* vfs_rename - rename a filesystem object
|
|
* @old_dir: parent of source
|
|
* @old_dentry: source
|
|
* @new_dir: parent of destination
|
|
* @new_dentry: destination
|
|
* @delegated_inode: returns an inode needing a delegation break
|
|
*
|
|
* The caller must hold multiple mutexes--see lock_rename()).
|
|
*
|
|
* If vfs_rename discovers a delegation in need of breaking at either
|
|
* the source or destination, it will return -EWOULDBLOCK and return a
|
|
* reference to the inode in delegated_inode. The caller should then
|
|
* break the delegation and retry. Because breaking a delegation may
|
|
* take a long time, the caller should drop all locks before doing
|
|
* so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*/
|
|
int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry,
|
|
struct inode **delegated_inode)
|
|
{
|
|
int error;
|
|
int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry);
|
|
const unsigned char *old_name;
|
|
|
|
if (old_dentry->d_inode == new_dentry->d_inode)
|
|
return 0;
|
|
|
|
error = may_delete(old_dir, old_dentry, is_dir);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!new_dentry->d_inode)
|
|
error = may_create(new_dir, new_dentry);
|
|
else
|
|
error = may_delete(new_dir, new_dentry, is_dir);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!old_dir->i_op->rename)
|
|
return -EPERM;
|
|
|
|
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
|
|
|
|
if (is_dir)
|
|
error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
|
|
else
|
|
error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry,delegated_inode);
|
|
if (!error)
|
|
fsnotify_move(old_dir, new_dir, old_name, is_dir,
|
|
new_dentry->d_inode, old_dentry);
|
|
fsnotify_oldname_free(old_name);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
struct dentry *old_dir, *new_dir;
|
|
struct dentry *old_dentry, *new_dentry;
|
|
struct dentry *trap;
|
|
struct nameidata oldnd, newnd;
|
|
struct inode *delegated_inode = NULL;
|
|
struct filename *from;
|
|
struct filename *to;
|
|
unsigned int lookup_flags = 0;
|
|
bool should_retry = false;
|
|
int error;
|
|
retry:
|
|
from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags);
|
|
if (IS_ERR(from)) {
|
|
error = PTR_ERR(from);
|
|
goto exit;
|
|
}
|
|
|
|
to = user_path_parent(newdfd, newname, &newnd, lookup_flags);
|
|
if (IS_ERR(to)) {
|
|
error = PTR_ERR(to);
|
|
goto exit1;
|
|
}
|
|
|
|
error = -EXDEV;
|
|
if (oldnd.path.mnt != newnd.path.mnt)
|
|
goto exit2;
|
|
|
|
old_dir = oldnd.path.dentry;
|
|
error = -EBUSY;
|
|
if (oldnd.last_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
new_dir = newnd.path.dentry;
|
|
if (newnd.last_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
error = mnt_want_write(oldnd.path.mnt);
|
|
if (error)
|
|
goto exit2;
|
|
|
|
oldnd.flags &= ~LOOKUP_PARENT;
|
|
newnd.flags &= ~LOOKUP_PARENT;
|
|
newnd.flags |= LOOKUP_RENAME_TARGET;
|
|
|
|
retry_deleg:
|
|
trap = lock_rename(new_dir, old_dir);
|
|
|
|
old_dentry = lookup_hash(&oldnd);
|
|
error = PTR_ERR(old_dentry);
|
|
if (IS_ERR(old_dentry))
|
|
goto exit3;
|
|
/* source must exist */
|
|
error = -ENOENT;
|
|
if (d_is_negative(old_dentry))
|
|
goto exit4;
|
|
/* unless the source is a directory trailing slashes give -ENOTDIR */
|
|
if (!d_is_directory(old_dentry) && !d_is_autodir(old_dentry)) {
|
|
error = -ENOTDIR;
|
|
if (oldnd.last.name[oldnd.last.len])
|
|
goto exit4;
|
|
if (newnd.last.name[newnd.last.len])
|
|
goto exit4;
|
|
}
|
|
/* source should not be ancestor of target */
|
|
error = -EINVAL;
|
|
if (old_dentry == trap)
|
|
goto exit4;
|
|
new_dentry = lookup_hash(&newnd);
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto exit4;
|
|
/* target should not be an ancestor of source */
|
|
error = -ENOTEMPTY;
|
|
if (new_dentry == trap)
|
|
goto exit5;
|
|
|
|
error = security_path_rename(&oldnd.path, old_dentry,
|
|
&newnd.path, new_dentry);
|
|
if (error)
|
|
goto exit5;
|
|
error = vfs_rename(old_dir->d_inode, old_dentry,
|
|
new_dir->d_inode, new_dentry,
|
|
&delegated_inode);
|
|
exit5:
|
|
dput(new_dentry);
|
|
exit4:
|
|
dput(old_dentry);
|
|
exit3:
|
|
unlock_rename(new_dir, old_dir);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(oldnd.path.mnt);
|
|
exit2:
|
|
if (retry_estale(error, lookup_flags))
|
|
should_retry = true;
|
|
path_put(&newnd.path);
|
|
putname(to);
|
|
exit1:
|
|
path_put(&oldnd.path);
|
|
putname(from);
|
|
if (should_retry) {
|
|
should_retry = false;
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
exit:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
|
|
}
|
|
|
|
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
|
|
{
|
|
int len;
|
|
|
|
len = PTR_ERR(link);
|
|
if (IS_ERR(link))
|
|
goto out;
|
|
|
|
len = strlen(link);
|
|
if (len > (unsigned) buflen)
|
|
len = buflen;
|
|
if (copy_to_user(buffer, link, len))
|
|
len = -EFAULT;
|
|
out:
|
|
return len;
|
|
}
|
|
|
|
/*
|
|
* A helper for ->readlink(). This should be used *ONLY* for symlinks that
|
|
* have ->follow_link() touching nd only in nd_set_link(). Using (or not
|
|
* using) it for any given inode is up to filesystem.
|
|
*/
|
|
int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
struct nameidata nd;
|
|
void *cookie;
|
|
int res;
|
|
|
|
nd.depth = 0;
|
|
cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
|
|
if (IS_ERR(cookie))
|
|
return PTR_ERR(cookie);
|
|
|
|
res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
|
|
if (dentry->d_inode->i_op->put_link)
|
|
dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
|
|
return res;
|
|
}
|
|
|
|
/* get the link contents into pagecache */
|
|
static char *page_getlink(struct dentry * dentry, struct page **ppage)
|
|
{
|
|
char *kaddr;
|
|
struct page *page;
|
|
struct address_space *mapping = dentry->d_inode->i_mapping;
|
|
page = read_mapping_page(mapping, 0, NULL);
|
|
if (IS_ERR(page))
|
|
return (char*)page;
|
|
*ppage = page;
|
|
kaddr = kmap(page);
|
|
nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
|
|
return kaddr;
|
|
}
|
|
|
|
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
struct page *page = NULL;
|
|
char *s = page_getlink(dentry, &page);
|
|
int res = vfs_readlink(dentry,buffer,buflen,s);
|
|
if (page) {
|
|
kunmap(page);
|
|
page_cache_release(page);
|
|
}
|
|
return res;
|
|
}
|
|
|
|
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
|
|
{
|
|
struct page *page = NULL;
|
|
nd_set_link(nd, page_getlink(dentry, &page));
|
|
return page;
|
|
}
|
|
|
|
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
|
|
{
|
|
struct page *page = cookie;
|
|
|
|
if (page) {
|
|
kunmap(page);
|
|
page_cache_release(page);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
|
|
*/
|
|
int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct page *page;
|
|
void *fsdata;
|
|
int err;
|
|
char *kaddr;
|
|
unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
|
|
if (nofs)
|
|
flags |= AOP_FLAG_NOFS;
|
|
|
|
retry:
|
|
err = pagecache_write_begin(NULL, mapping, 0, len-1,
|
|
flags, &page, &fsdata);
|
|
if (err)
|
|
goto fail;
|
|
|
|
kaddr = kmap_atomic(page);
|
|
memcpy(kaddr, symname, len-1);
|
|
kunmap_atomic(kaddr);
|
|
|
|
err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto fail;
|
|
if (err < len-1)
|
|
goto retry;
|
|
|
|
mark_inode_dirty(inode);
|
|
return 0;
|
|
fail:
|
|
return err;
|
|
}
|
|
|
|
int page_symlink(struct inode *inode, const char *symname, int len)
|
|
{
|
|
return __page_symlink(inode, symname, len,
|
|
!(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
|
|
}
|
|
|
|
const struct inode_operations page_symlink_inode_operations = {
|
|
.readlink = generic_readlink,
|
|
.follow_link = page_follow_link_light,
|
|
.put_link = page_put_link,
|
|
};
|
|
|
|
EXPORT_SYMBOL(user_path_at);
|
|
EXPORT_SYMBOL(follow_down_one);
|
|
EXPORT_SYMBOL(follow_down);
|
|
EXPORT_SYMBOL(follow_up);
|
|
EXPORT_SYMBOL(get_write_access); /* nfsd */
|
|
EXPORT_SYMBOL(lock_rename);
|
|
EXPORT_SYMBOL(lookup_one_len);
|
|
EXPORT_SYMBOL(page_follow_link_light);
|
|
EXPORT_SYMBOL(page_put_link);
|
|
EXPORT_SYMBOL(page_readlink);
|
|
EXPORT_SYMBOL(__page_symlink);
|
|
EXPORT_SYMBOL(page_symlink);
|
|
EXPORT_SYMBOL(page_symlink_inode_operations);
|
|
EXPORT_SYMBOL(kern_path);
|
|
EXPORT_SYMBOL(vfs_path_lookup);
|
|
EXPORT_SYMBOL(inode_permission);
|
|
EXPORT_SYMBOL(unlock_rename);
|
|
EXPORT_SYMBOL(vfs_create);
|
|
EXPORT_SYMBOL(vfs_link);
|
|
EXPORT_SYMBOL(vfs_mkdir);
|
|
EXPORT_SYMBOL(vfs_mknod);
|
|
EXPORT_SYMBOL(generic_permission);
|
|
EXPORT_SYMBOL(vfs_readlink);
|
|
EXPORT_SYMBOL(vfs_rename);
|
|
EXPORT_SYMBOL(vfs_rmdir);
|
|
EXPORT_SYMBOL(vfs_symlink);
|
|
EXPORT_SYMBOL(vfs_unlink);
|
|
EXPORT_SYMBOL(dentry_unhash);
|
|
EXPORT_SYMBOL(generic_readlink);
|