1287 lines
34 KiB
C
1287 lines
34 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (C) 2011 Novell Inc.
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*/
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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#include <linux/xattr.h>
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#include <linux/posix_acl.h>
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#include <linux/ratelimit.h>
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#include <linux/fiemap.h>
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#include <linux/fileattr.h>
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#include <linux/security.h>
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#include <linux/namei.h>
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#include "overlayfs.h"
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int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
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struct iattr *attr)
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{
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int err;
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struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
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bool full_copy_up = false;
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struct dentry *upperdentry;
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const struct cred *old_cred;
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err = setattr_prepare(&init_user_ns, dentry, attr);
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if (err)
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return err;
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err = ovl_want_write(dentry);
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if (err)
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goto out;
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if (attr->ia_valid & ATTR_SIZE) {
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/* Truncate should trigger data copy up as well */
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full_copy_up = true;
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}
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if (!full_copy_up)
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err = ovl_copy_up(dentry);
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else
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err = ovl_copy_up_with_data(dentry);
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if (!err) {
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struct inode *winode = NULL;
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upperdentry = ovl_dentry_upper(dentry);
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if (attr->ia_valid & ATTR_SIZE) {
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winode = d_inode(upperdentry);
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err = get_write_access(winode);
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if (err)
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goto out_drop_write;
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}
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if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
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attr->ia_valid &= ~ATTR_MODE;
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/*
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* We might have to translate ovl file into real file object
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* once use cases emerge. For now, simply don't let underlying
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* filesystem rely on attr->ia_file
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*/
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attr->ia_valid &= ~ATTR_FILE;
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/*
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* If open(O_TRUNC) is done, VFS calls ->setattr with ATTR_OPEN
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* set. Overlayfs does not pass O_TRUNC flag to underlying
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* filesystem during open -> do not pass ATTR_OPEN. This
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* disables optimization in fuse which assumes open(O_TRUNC)
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* already set file size to 0. But we never passed O_TRUNC to
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* fuse. So by clearing ATTR_OPEN, fuse will be forced to send
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* setattr request to server.
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*/
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attr->ia_valid &= ~ATTR_OPEN;
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inode_lock(upperdentry->d_inode);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = ovl_do_notify_change(ofs, upperdentry, attr);
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revert_creds(old_cred);
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if (!err)
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ovl_copyattr(dentry->d_inode);
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inode_unlock(upperdentry->d_inode);
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if (winode)
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put_write_access(winode);
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}
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out_drop_write:
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ovl_drop_write(dentry);
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out:
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return err;
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}
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static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
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{
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bool samefs = ovl_same_fs(dentry->d_sb);
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unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
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unsigned int xinoshift = 64 - xinobits;
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if (samefs) {
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/*
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* When all layers are on the same fs, all real inode
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* number are unique, so we use the overlay st_dev,
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* which is friendly to du -x.
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*/
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stat->dev = dentry->d_sb->s_dev;
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return;
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} else if (xinobits) {
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/*
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* All inode numbers of underlying fs should not be using the
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* high xinobits, so we use high xinobits to partition the
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* overlay st_ino address space. The high bits holds the fsid
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* (upper fsid is 0). The lowest xinobit is reserved for mapping
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* the non-persistent inode numbers range in case of overflow.
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* This way all overlay inode numbers are unique and use the
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* overlay st_dev.
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*/
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if (likely(!(stat->ino >> xinoshift))) {
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stat->ino |= ((u64)fsid) << (xinoshift + 1);
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stat->dev = dentry->d_sb->s_dev;
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return;
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} else if (ovl_xino_warn(dentry->d_sb)) {
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pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
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dentry, stat->ino, xinobits);
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}
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}
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/* The inode could not be mapped to a unified st_ino address space */
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if (S_ISDIR(dentry->d_inode->i_mode)) {
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/*
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* Always use the overlay st_dev for directories, so 'find
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* -xdev' will scan the entire overlay mount and won't cross the
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* overlay mount boundaries.
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*
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* If not all layers are on the same fs the pair {real st_ino;
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* overlay st_dev} is not unique, so use the non persistent
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* overlay st_ino for directories.
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*/
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stat->dev = dentry->d_sb->s_dev;
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stat->ino = dentry->d_inode->i_ino;
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} else {
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/*
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* For non-samefs setup, if we cannot map all layers st_ino
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* to a unified address space, we need to make sure that st_dev
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* is unique per underlying fs, so we use the unique anonymous
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* bdev assigned to the underlying fs.
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*/
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stat->dev = OVL_FS(dentry->d_sb)->fs[fsid].pseudo_dev;
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}
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}
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int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
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struct kstat *stat, u32 request_mask, unsigned int flags)
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{
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struct dentry *dentry = path->dentry;
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enum ovl_path_type type;
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struct path realpath;
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const struct cred *old_cred;
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struct inode *inode = d_inode(dentry);
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bool is_dir = S_ISDIR(inode->i_mode);
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int fsid = 0;
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int err;
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bool metacopy_blocks = false;
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metacopy_blocks = ovl_is_metacopy_dentry(dentry);
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type = ovl_path_real(dentry, &realpath);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = vfs_getattr(&realpath, stat, request_mask, flags);
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if (err)
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goto out;
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/* Report the effective immutable/append-only STATX flags */
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generic_fill_statx_attr(inode, stat);
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/*
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* For non-dir or same fs, we use st_ino of the copy up origin.
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* This guaranties constant st_dev/st_ino across copy up.
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* With xino feature and non-samefs, we use st_ino of the copy up
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* origin masked with high bits that represent the layer id.
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*
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* If lower filesystem supports NFS file handles, this also guaranties
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* persistent st_ino across mount cycle.
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*/
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if (!is_dir || ovl_same_dev(dentry->d_sb)) {
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if (!OVL_TYPE_UPPER(type)) {
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fsid = ovl_layer_lower(dentry)->fsid;
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} else if (OVL_TYPE_ORIGIN(type)) {
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struct kstat lowerstat;
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u32 lowermask = STATX_INO | STATX_BLOCKS |
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(!is_dir ? STATX_NLINK : 0);
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ovl_path_lower(dentry, &realpath);
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err = vfs_getattr(&realpath, &lowerstat,
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lowermask, flags);
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if (err)
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goto out;
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/*
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* Lower hardlinks may be broken on copy up to different
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* upper files, so we cannot use the lower origin st_ino
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* for those different files, even for the same fs case.
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*
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* Similarly, several redirected dirs can point to the
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* same dir on a lower layer. With the "verify_lower"
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* feature, we do not use the lower origin st_ino, if
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* we haven't verified that this redirect is unique.
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*
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* With inodes index enabled, it is safe to use st_ino
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* of an indexed origin. The index validates that the
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* upper hardlink is not broken and that a redirected
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* dir is the only redirect to that origin.
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*/
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if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
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(!ovl_verify_lower(dentry->d_sb) &&
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(is_dir || lowerstat.nlink == 1))) {
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fsid = ovl_layer_lower(dentry)->fsid;
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stat->ino = lowerstat.ino;
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}
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/*
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* If we are querying a metacopy dentry and lower
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* dentry is data dentry, then use the blocks we
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* queried just now. We don't have to do additional
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* vfs_getattr(). If lower itself is metacopy, then
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* additional vfs_getattr() is unavoidable.
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*/
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if (metacopy_blocks &&
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realpath.dentry == ovl_dentry_lowerdata(dentry)) {
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stat->blocks = lowerstat.blocks;
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metacopy_blocks = false;
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}
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}
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if (metacopy_blocks) {
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/*
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* If lower is not same as lowerdata or if there was
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* no origin on upper, we can end up here.
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*/
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struct kstat lowerdatastat;
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u32 lowermask = STATX_BLOCKS;
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ovl_path_lowerdata(dentry, &realpath);
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err = vfs_getattr(&realpath, &lowerdatastat,
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lowermask, flags);
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if (err)
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goto out;
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stat->blocks = lowerdatastat.blocks;
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}
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}
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ovl_map_dev_ino(dentry, stat, fsid);
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/*
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* It's probably not worth it to count subdirs to get the
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* correct link count. nlink=1 seems to pacify 'find' and
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* other utilities.
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*/
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if (is_dir && OVL_TYPE_MERGE(type))
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stat->nlink = 1;
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/*
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* Return the overlay inode nlinks for indexed upper inodes.
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* Overlay inode nlink counts the union of the upper hardlinks
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* and non-covered lower hardlinks. It does not include the upper
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* index hardlink.
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*/
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if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
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stat->nlink = dentry->d_inode->i_nlink;
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out:
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revert_creds(old_cred);
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return err;
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}
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int ovl_permission(struct user_namespace *mnt_userns,
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struct inode *inode, int mask)
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{
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struct inode *upperinode = ovl_inode_upper(inode);
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struct inode *realinode;
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struct path realpath;
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const struct cred *old_cred;
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int err;
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/* Careful in RCU walk mode */
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ovl_i_path_real(inode, &realpath);
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if (!realpath.dentry) {
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WARN_ON(!(mask & MAY_NOT_BLOCK));
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return -ECHILD;
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}
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/*
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* Check overlay inode with the creds of task and underlying inode
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* with creds of mounter
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*/
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err = generic_permission(&init_user_ns, inode, mask);
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if (err)
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return err;
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realinode = d_inode(realpath.dentry);
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old_cred = ovl_override_creds(inode->i_sb);
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if (!upperinode &&
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!special_file(realinode->i_mode) && mask & MAY_WRITE) {
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mask &= ~(MAY_WRITE | MAY_APPEND);
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/* Make sure mounter can read file for copy up later */
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mask |= MAY_READ;
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}
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err = inode_permission(mnt_user_ns(realpath.mnt), realinode, mask);
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revert_creds(old_cred);
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return err;
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}
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static const char *ovl_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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const struct cred *old_cred;
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const char *p;
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if (!dentry)
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return ERR_PTR(-ECHILD);
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old_cred = ovl_override_creds(dentry->d_sb);
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p = vfs_get_link(ovl_dentry_real(dentry), done);
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revert_creds(old_cred);
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return p;
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}
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bool ovl_is_private_xattr(struct super_block *sb, const char *name)
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{
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struct ovl_fs *ofs = sb->s_fs_info;
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if (ofs->config.userxattr)
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return strncmp(name, OVL_XATTR_USER_PREFIX,
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sizeof(OVL_XATTR_USER_PREFIX) - 1) == 0;
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else
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return strncmp(name, OVL_XATTR_TRUSTED_PREFIX,
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sizeof(OVL_XATTR_TRUSTED_PREFIX) - 1) == 0;
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}
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int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
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const void *value, size_t size, int flags)
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{
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int err;
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struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
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struct dentry *upperdentry = ovl_i_dentry_upper(inode);
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struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
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struct path realpath;
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const struct cred *old_cred;
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err = ovl_want_write(dentry);
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if (err)
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goto out;
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if (!value && !upperdentry) {
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ovl_path_lower(dentry, &realpath);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = vfs_getxattr(mnt_user_ns(realpath.mnt), realdentry, name, NULL, 0);
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revert_creds(old_cred);
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if (err < 0)
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goto out_drop_write;
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}
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if (!upperdentry) {
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err = ovl_copy_up(dentry);
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if (err)
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goto out_drop_write;
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realdentry = ovl_dentry_upper(dentry);
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}
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old_cred = ovl_override_creds(dentry->d_sb);
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if (value) {
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err = ovl_do_setxattr(ofs, realdentry, name, value, size,
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flags);
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} else {
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WARN_ON(flags != XATTR_REPLACE);
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err = ovl_do_removexattr(ofs, realdentry, name);
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}
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revert_creds(old_cred);
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/* copy c/mtime */
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ovl_copyattr(inode);
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out_drop_write:
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ovl_drop_write(dentry);
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out:
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return err;
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}
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int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
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void *value, size_t size)
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{
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ssize_t res;
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const struct cred *old_cred;
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struct path realpath;
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ovl_i_path_real(inode, &realpath);
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old_cred = ovl_override_creds(dentry->d_sb);
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res = vfs_getxattr(mnt_user_ns(realpath.mnt), realpath.dentry, name, value, size);
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revert_creds(old_cred);
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return res;
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}
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static bool ovl_can_list(struct super_block *sb, const char *s)
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{
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/* Never list private (.overlay) */
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if (ovl_is_private_xattr(sb, s))
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return false;
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/* List all non-trusted xattrs */
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if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
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return true;
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/* list other trusted for superuser only */
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return ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
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}
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ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
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{
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struct dentry *realdentry = ovl_dentry_real(dentry);
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ssize_t res;
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size_t len;
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char *s;
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const struct cred *old_cred;
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old_cred = ovl_override_creds(dentry->d_sb);
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res = vfs_listxattr(realdentry, list, size);
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revert_creds(old_cred);
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if (res <= 0 || size == 0)
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return res;
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/* filter out private xattrs */
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for (s = list, len = res; len;) {
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size_t slen = strnlen(s, len) + 1;
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|
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/* underlying fs providing us with an broken xattr list? */
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if (WARN_ON(slen > len))
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return -EIO;
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len -= slen;
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if (!ovl_can_list(dentry->d_sb, s)) {
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res -= slen;
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memmove(s, s + slen, len);
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} else {
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s += slen;
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}
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}
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|
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return res;
|
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}
|
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|
|
#ifdef CONFIG_FS_POSIX_ACL
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/*
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* Apply the idmapping of the layer to POSIX ACLs. The caller must pass a clone
|
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* of the POSIX ACLs retrieved from the lower layer to this function to not
|
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* alter the POSIX ACLs for the underlying filesystem.
|
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*/
|
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static void ovl_idmap_posix_acl(struct inode *realinode,
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struct user_namespace *mnt_userns,
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struct posix_acl *acl)
|
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{
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struct user_namespace *fs_userns = i_user_ns(realinode);
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for (unsigned int i = 0; i < acl->a_count; i++) {
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vfsuid_t vfsuid;
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vfsgid_t vfsgid;
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|
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struct posix_acl_entry *e = &acl->a_entries[i];
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switch (e->e_tag) {
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case ACL_USER:
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vfsuid = make_vfsuid(mnt_userns, fs_userns, e->e_uid);
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e->e_uid = vfsuid_into_kuid(vfsuid);
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break;
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case ACL_GROUP:
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vfsgid = make_vfsgid(mnt_userns, fs_userns, e->e_gid);
|
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e->e_gid = vfsgid_into_kgid(vfsgid);
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break;
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}
|
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}
|
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}
|
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|
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/*
|
|
* When the relevant layer is an idmapped mount we need to take the idmapping
|
|
* of the layer into account and translate any ACL_{GROUP,USER} values
|
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* according to the idmapped mount.
|
|
*
|
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* We cannot alter the ACLs returned from the relevant layer as that would
|
|
* alter the cached values filesystem wide for the lower filesystem. Instead we
|
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* can clone the ACLs and then apply the relevant idmapping of the layer.
|
|
*
|
|
* This is obviously only relevant when idmapped layers are used.
|
|
*/
|
|
struct posix_acl *ovl_get_acl(struct inode *inode, int type, bool rcu)
|
|
{
|
|
struct inode *realinode = ovl_inode_real(inode);
|
|
struct posix_acl *acl, *clone;
|
|
struct path realpath;
|
|
|
|
if (!IS_POSIXACL(realinode))
|
|
return NULL;
|
|
|
|
/* Careful in RCU walk mode */
|
|
ovl_i_path_real(inode, &realpath);
|
|
if (!realpath.dentry) {
|
|
WARN_ON(!rcu);
|
|
return ERR_PTR(-ECHILD);
|
|
}
|
|
|
|
if (rcu) {
|
|
acl = get_cached_acl_rcu(realinode, type);
|
|
} else {
|
|
const struct cred *old_cred;
|
|
|
|
old_cred = ovl_override_creds(inode->i_sb);
|
|
acl = get_acl(realinode, type);
|
|
revert_creds(old_cred);
|
|
}
|
|
/*
|
|
* If there are no POSIX ACLs, or we encountered an error,
|
|
* or the layer isn't idmapped we don't need to do anything.
|
|
*/
|
|
if (!is_idmapped_mnt(realpath.mnt) || IS_ERR_OR_NULL(acl))
|
|
return acl;
|
|
|
|
/*
|
|
* We only get here if the layer is idmapped. So drop out of RCU path
|
|
* walk so we can clone the ACLs. There's no need to release the ACLs
|
|
* since get_cached_acl_rcu() doesn't take a reference on the ACLs.
|
|
*/
|
|
if (rcu)
|
|
return ERR_PTR(-ECHILD);
|
|
|
|
clone = posix_acl_clone(acl, GFP_KERNEL);
|
|
if (!clone)
|
|
clone = ERR_PTR(-ENOMEM);
|
|
else
|
|
ovl_idmap_posix_acl(realinode, mnt_user_ns(realpath.mnt), clone);
|
|
/*
|
|
* Since we're not in RCU path walk we always need to release the
|
|
* original ACLs.
|
|
*/
|
|
posix_acl_release(acl);
|
|
return clone;
|
|
}
|
|
#endif
|
|
|
|
int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
|
|
{
|
|
if (flags & S_ATIME) {
|
|
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
|
|
struct path upperpath = {
|
|
.mnt = ovl_upper_mnt(ofs),
|
|
.dentry = ovl_upperdentry_dereference(OVL_I(inode)),
|
|
};
|
|
|
|
if (upperpath.dentry) {
|
|
touch_atime(&upperpath);
|
|
inode->i_atime = d_inode(upperpath.dentry)->i_atime;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
|
|
u64 start, u64 len)
|
|
{
|
|
int err;
|
|
struct inode *realinode = ovl_inode_realdata(inode);
|
|
const struct cred *old_cred;
|
|
|
|
if (!realinode->i_op->fiemap)
|
|
return -EOPNOTSUPP;
|
|
|
|
old_cred = ovl_override_creds(inode->i_sb);
|
|
err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
|
|
revert_creds(old_cred);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Work around the fact that security_file_ioctl() takes a file argument.
|
|
* Introducing security_inode_fileattr_get/set() hooks would solve this issue
|
|
* properly.
|
|
*/
|
|
static int ovl_security_fileattr(struct path *realpath, struct fileattr *fa,
|
|
bool set)
|
|
{
|
|
struct file *file;
|
|
unsigned int cmd;
|
|
int err;
|
|
|
|
file = dentry_open(realpath, O_RDONLY, current_cred());
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
if (set)
|
|
cmd = fa->fsx_valid ? FS_IOC_FSSETXATTR : FS_IOC_SETFLAGS;
|
|
else
|
|
cmd = fa->fsx_valid ? FS_IOC_FSGETXATTR : FS_IOC_GETFLAGS;
|
|
|
|
err = security_file_ioctl(file, cmd, 0);
|
|
fput(file);
|
|
|
|
return err;
|
|
}
|
|
|
|
int ovl_real_fileattr_set(struct path *realpath, struct fileattr *fa)
|
|
{
|
|
int err;
|
|
|
|
err = ovl_security_fileattr(realpath, fa, true);
|
|
if (err)
|
|
return err;
|
|
|
|
return vfs_fileattr_set(mnt_user_ns(realpath->mnt), realpath->dentry, fa);
|
|
}
|
|
|
|
int ovl_fileattr_set(struct user_namespace *mnt_userns,
|
|
struct dentry *dentry, struct fileattr *fa)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
struct path upperpath;
|
|
const struct cred *old_cred;
|
|
unsigned int flags;
|
|
int err;
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = ovl_copy_up(dentry);
|
|
if (!err) {
|
|
ovl_path_real(dentry, &upperpath);
|
|
|
|
old_cred = ovl_override_creds(inode->i_sb);
|
|
/*
|
|
* Store immutable/append-only flags in xattr and clear them
|
|
* in upper fileattr (in case they were set by older kernel)
|
|
* so children of "ovl-immutable" directories lower aliases of
|
|
* "ovl-immutable" hardlinks could be copied up.
|
|
* Clear xattr when flags are cleared.
|
|
*/
|
|
err = ovl_set_protattr(inode, upperpath.dentry, fa);
|
|
if (!err)
|
|
err = ovl_real_fileattr_set(&upperpath, fa);
|
|
revert_creds(old_cred);
|
|
|
|
/*
|
|
* Merge real inode flags with inode flags read from
|
|
* overlay.protattr xattr
|
|
*/
|
|
flags = ovl_inode_real(inode)->i_flags & OVL_COPY_I_FLAGS_MASK;
|
|
|
|
BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
|
|
flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
|
|
inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
|
|
|
|
/* Update ctime */
|
|
ovl_copyattr(inode);
|
|
}
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/* Convert inode protection flags to fileattr flags */
|
|
static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
|
|
{
|
|
BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
|
|
BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
|
|
|
|
if (inode->i_flags & S_APPEND) {
|
|
fa->flags |= FS_APPEND_FL;
|
|
fa->fsx_xflags |= FS_XFLAG_APPEND;
|
|
}
|
|
if (inode->i_flags & S_IMMUTABLE) {
|
|
fa->flags |= FS_IMMUTABLE_FL;
|
|
fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
|
|
}
|
|
}
|
|
|
|
int ovl_real_fileattr_get(struct path *realpath, struct fileattr *fa)
|
|
{
|
|
int err;
|
|
|
|
err = ovl_security_fileattr(realpath, fa, false);
|
|
if (err)
|
|
return err;
|
|
|
|
err = vfs_fileattr_get(realpath->dentry, fa);
|
|
if (err == -ENOIOCTLCMD)
|
|
err = -ENOTTY;
|
|
return err;
|
|
}
|
|
|
|
int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
struct path realpath;
|
|
const struct cred *old_cred;
|
|
int err;
|
|
|
|
ovl_path_real(dentry, &realpath);
|
|
|
|
old_cred = ovl_override_creds(inode->i_sb);
|
|
err = ovl_real_fileattr_get(&realpath, fa);
|
|
ovl_fileattr_prot_flags(inode, fa);
|
|
revert_creds(old_cred);
|
|
|
|
return err;
|
|
}
|
|
|
|
static const struct inode_operations ovl_file_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.permission = ovl_permission,
|
|
.getattr = ovl_getattr,
|
|
.listxattr = ovl_listxattr,
|
|
.get_acl = ovl_get_acl,
|
|
.update_time = ovl_update_time,
|
|
.fiemap = ovl_fiemap,
|
|
.fileattr_get = ovl_fileattr_get,
|
|
.fileattr_set = ovl_fileattr_set,
|
|
};
|
|
|
|
static const struct inode_operations ovl_symlink_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.get_link = ovl_get_link,
|
|
.getattr = ovl_getattr,
|
|
.listxattr = ovl_listxattr,
|
|
.update_time = ovl_update_time,
|
|
};
|
|
|
|
static const struct inode_operations ovl_special_inode_operations = {
|
|
.setattr = ovl_setattr,
|
|
.permission = ovl_permission,
|
|
.getattr = ovl_getattr,
|
|
.listxattr = ovl_listxattr,
|
|
.get_acl = ovl_get_acl,
|
|
.update_time = ovl_update_time,
|
|
};
|
|
|
|
static const struct address_space_operations ovl_aops = {
|
|
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
|
|
.direct_IO = noop_direct_IO,
|
|
};
|
|
|
|
/*
|
|
* It is possible to stack overlayfs instance on top of another
|
|
* overlayfs instance as lower layer. We need to annotate the
|
|
* stackable i_mutex locks according to stack level of the super
|
|
* block instance. An overlayfs instance can never be in stack
|
|
* depth 0 (there is always a real fs below it). An overlayfs
|
|
* inode lock will use the lockdep annotation ovl_i_mutex_key[depth].
|
|
*
|
|
* For example, here is a snip from /proc/lockdep_chains after
|
|
* dir_iterate of nested overlayfs:
|
|
*
|
|
* [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
|
|
* [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
|
|
* [...] &type->i_mutex_dir_key (stack_depth=0)
|
|
*
|
|
* Locking order w.r.t ovl_want_write() is important for nested overlayfs.
|
|
*
|
|
* This chain is valid:
|
|
* - inode->i_rwsem (inode_lock[2])
|
|
* - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
|
|
* - OVL_I(inode)->lock (ovl_inode_lock[2])
|
|
* - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
|
|
*
|
|
* And this chain is valid:
|
|
* - inode->i_rwsem (inode_lock[2])
|
|
* - OVL_I(inode)->lock (ovl_inode_lock[2])
|
|
* - lowerinode->i_rwsem (inode_lock[1])
|
|
* - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
|
|
*
|
|
* But lowerinode->i_rwsem SHOULD NOT be acquired while ovl_want_write() is
|
|
* held, because it is in reverse order of the non-nested case using the same
|
|
* upper fs:
|
|
* - inode->i_rwsem (inode_lock[1])
|
|
* - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
|
|
* - OVL_I(inode)->lock (ovl_inode_lock[1])
|
|
*/
|
|
#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
|
|
|
|
static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
|
|
{
|
|
#ifdef CONFIG_LOCKDEP
|
|
static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING];
|
|
static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING];
|
|
static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING];
|
|
|
|
int depth = inode->i_sb->s_stack_depth - 1;
|
|
|
|
if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING))
|
|
depth = 0;
|
|
|
|
if (S_ISDIR(inode->i_mode))
|
|
lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]);
|
|
else
|
|
lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]);
|
|
|
|
lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]);
|
|
#endif
|
|
}
|
|
|
|
static void ovl_next_ino(struct inode *inode)
|
|
{
|
|
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
|
|
|
|
inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
|
|
if (unlikely(!inode->i_ino))
|
|
inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
|
|
}
|
|
|
|
static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid)
|
|
{
|
|
int xinobits = ovl_xino_bits(inode->i_sb);
|
|
unsigned int xinoshift = 64 - xinobits;
|
|
|
|
/*
|
|
* When d_ino is consistent with st_ino (samefs or i_ino has enough
|
|
* bits to encode layer), set the same value used for st_ino to i_ino,
|
|
* so inode number exposed via /proc/locks and a like will be
|
|
* consistent with d_ino and st_ino values. An i_ino value inconsistent
|
|
* with d_ino also causes nfsd readdirplus to fail.
|
|
*/
|
|
inode->i_ino = ino;
|
|
if (ovl_same_fs(inode->i_sb)) {
|
|
return;
|
|
} else if (xinobits && likely(!(ino >> xinoshift))) {
|
|
inode->i_ino |= (unsigned long)fsid << (xinoshift + 1);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* For directory inodes on non-samefs with xino disabled or xino
|
|
* overflow, we allocate a non-persistent inode number, to be used for
|
|
* resolving st_ino collisions in ovl_map_dev_ino().
|
|
*
|
|
* To avoid ino collision with legitimate xino values from upper
|
|
* layer (fsid 0), use the lowest xinobit to map the non
|
|
* persistent inode numbers to the unified st_ino address space.
|
|
*/
|
|
if (S_ISDIR(inode->i_mode)) {
|
|
ovl_next_ino(inode);
|
|
if (xinobits) {
|
|
inode->i_ino &= ~0UL >> xinobits;
|
|
inode->i_ino |= 1UL << xinoshift;
|
|
}
|
|
}
|
|
}
|
|
|
|
void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
|
|
unsigned long ino, int fsid)
|
|
{
|
|
struct inode *realinode;
|
|
struct ovl_inode *oi = OVL_I(inode);
|
|
|
|
if (oip->upperdentry)
|
|
oi->__upperdentry = oip->upperdentry;
|
|
if (oip->lowerpath && oip->lowerpath->dentry) {
|
|
oi->lowerpath.dentry = dget(oip->lowerpath->dentry);
|
|
oi->lowerpath.layer = oip->lowerpath->layer;
|
|
}
|
|
if (oip->lowerdata)
|
|
oi->lowerdata = igrab(d_inode(oip->lowerdata));
|
|
|
|
realinode = ovl_inode_real(inode);
|
|
ovl_copyattr(inode);
|
|
ovl_copyflags(realinode, inode);
|
|
ovl_map_ino(inode, ino, fsid);
|
|
}
|
|
|
|
static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
|
|
{
|
|
inode->i_mode = mode;
|
|
inode->i_flags |= S_NOCMTIME;
|
|
#ifdef CONFIG_FS_POSIX_ACL
|
|
inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
|
|
#endif
|
|
|
|
ovl_lockdep_annotate_inode_mutex_key(inode);
|
|
|
|
switch (mode & S_IFMT) {
|
|
case S_IFREG:
|
|
inode->i_op = &ovl_file_inode_operations;
|
|
inode->i_fop = &ovl_file_operations;
|
|
inode->i_mapping->a_ops = &ovl_aops;
|
|
break;
|
|
|
|
case S_IFDIR:
|
|
inode->i_op = &ovl_dir_inode_operations;
|
|
inode->i_fop = &ovl_dir_operations;
|
|
break;
|
|
|
|
case S_IFLNK:
|
|
inode->i_op = &ovl_symlink_inode_operations;
|
|
break;
|
|
|
|
default:
|
|
inode->i_op = &ovl_special_inode_operations;
|
|
init_special_inode(inode, mode, rdev);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* With inodes index enabled, an overlay inode nlink counts the union of upper
|
|
* hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
|
|
* upper inode, the following nlink modifying operations can happen:
|
|
*
|
|
* 1. Lower hardlink copy up
|
|
* 2. Upper hardlink created, unlinked or renamed over
|
|
* 3. Lower hardlink whiteout or renamed over
|
|
*
|
|
* For the first, copy up case, the union nlink does not change, whether the
|
|
* operation succeeds or fails, but the upper inode nlink may change.
|
|
* Therefore, before copy up, we store the union nlink value relative to the
|
|
* lower inode nlink in the index inode xattr .overlay.nlink.
|
|
*
|
|
* For the second, upper hardlink case, the union nlink should be incremented
|
|
* or decremented IFF the operation succeeds, aligned with nlink change of the
|
|
* upper inode. Therefore, before link/unlink/rename, we store the union nlink
|
|
* value relative to the upper inode nlink in the index inode.
|
|
*
|
|
* For the last, lower cover up case, we simplify things by preceding the
|
|
* whiteout or cover up with copy up. This makes sure that there is an index
|
|
* upper inode where the nlink xattr can be stored before the copied up upper
|
|
* entry is unlink.
|
|
*/
|
|
#define OVL_NLINK_ADD_UPPER (1 << 0)
|
|
|
|
/*
|
|
* On-disk format for indexed nlink:
|
|
*
|
|
* nlink relative to the upper inode - "U[+-]NUM"
|
|
* nlink relative to the lower inode - "L[+-]NUM"
|
|
*/
|
|
|
|
static int ovl_set_nlink_common(struct dentry *dentry,
|
|
struct dentry *realdentry, const char *format)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
struct inode *realinode = d_inode(realdentry);
|
|
char buf[13];
|
|
int len;
|
|
|
|
len = snprintf(buf, sizeof(buf), format,
|
|
(int) (inode->i_nlink - realinode->i_nlink));
|
|
|
|
if (WARN_ON(len >= sizeof(buf)))
|
|
return -EIO;
|
|
|
|
return ovl_setxattr(OVL_FS(inode->i_sb), ovl_dentry_upper(dentry),
|
|
OVL_XATTR_NLINK, buf, len);
|
|
}
|
|
|
|
int ovl_set_nlink_upper(struct dentry *dentry)
|
|
{
|
|
return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
|
|
}
|
|
|
|
int ovl_set_nlink_lower(struct dentry *dentry)
|
|
{
|
|
return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
|
|
}
|
|
|
|
unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
|
|
struct dentry *upperdentry,
|
|
unsigned int fallback)
|
|
{
|
|
int nlink_diff;
|
|
int nlink;
|
|
char buf[13];
|
|
int err;
|
|
|
|
if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
|
|
return fallback;
|
|
|
|
err = ovl_getxattr_upper(ofs, upperdentry, OVL_XATTR_NLINK,
|
|
&buf, sizeof(buf) - 1);
|
|
if (err < 0)
|
|
goto fail;
|
|
|
|
buf[err] = '\0';
|
|
if ((buf[0] != 'L' && buf[0] != 'U') ||
|
|
(buf[1] != '+' && buf[1] != '-'))
|
|
goto fail;
|
|
|
|
err = kstrtoint(buf + 1, 10, &nlink_diff);
|
|
if (err < 0)
|
|
goto fail;
|
|
|
|
nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
|
|
nlink += nlink_diff;
|
|
|
|
if (nlink <= 0)
|
|
goto fail;
|
|
|
|
return nlink;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("failed to get index nlink (%pd2, err=%i)\n",
|
|
upperdentry, err);
|
|
return fallback;
|
|
}
|
|
|
|
struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
|
|
{
|
|
struct inode *inode;
|
|
|
|
inode = new_inode(sb);
|
|
if (inode)
|
|
ovl_fill_inode(inode, mode, rdev);
|
|
|
|
return inode;
|
|
}
|
|
|
|
static int ovl_inode_test(struct inode *inode, void *data)
|
|
{
|
|
return inode->i_private == data;
|
|
}
|
|
|
|
static int ovl_inode_set(struct inode *inode, void *data)
|
|
{
|
|
inode->i_private = data;
|
|
return 0;
|
|
}
|
|
|
|
static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
|
|
struct dentry *upperdentry, bool strict)
|
|
{
|
|
/*
|
|
* For directories, @strict verify from lookup path performs consistency
|
|
* checks, so NULL lower/upper in dentry must match NULL lower/upper in
|
|
* inode. Non @strict verify from NFS handle decode path passes NULL for
|
|
* 'unknown' lower/upper.
|
|
*/
|
|
if (S_ISDIR(inode->i_mode) && strict) {
|
|
/* Real lower dir moved to upper layer under us? */
|
|
if (!lowerdentry && ovl_inode_lower(inode))
|
|
return false;
|
|
|
|
/* Lookup of an uncovered redirect origin? */
|
|
if (!upperdentry && ovl_inode_upper(inode))
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
|
|
* This happens when finding a copied up overlay inode for a renamed
|
|
* or hardlinked overlay dentry and lower dentry cannot be followed
|
|
* by origin because lower fs does not support file handles.
|
|
*/
|
|
if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
|
|
return false;
|
|
|
|
/*
|
|
* Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
|
|
* This happens when finding a lower alias for a copied up hard link.
|
|
*/
|
|
if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
|
|
bool is_upper)
|
|
{
|
|
struct inode *inode, *key = d_inode(real);
|
|
|
|
inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
|
|
if (!inode)
|
|
return NULL;
|
|
|
|
if (!ovl_verify_inode(inode, is_upper ? NULL : real,
|
|
is_upper ? real : NULL, false)) {
|
|
iput(inode);
|
|
return ERR_PTR(-ESTALE);
|
|
}
|
|
|
|
return inode;
|
|
}
|
|
|
|
bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir)
|
|
{
|
|
struct inode *key = d_inode(dir);
|
|
struct inode *trap;
|
|
bool res;
|
|
|
|
trap = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
|
|
if (!trap)
|
|
return false;
|
|
|
|
res = IS_DEADDIR(trap) && !ovl_inode_upper(trap) &&
|
|
!ovl_inode_lower(trap);
|
|
|
|
iput(trap);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Create an inode cache entry for layer root dir, that will intentionally
|
|
* fail ovl_verify_inode(), so any lookup that will find some layer root
|
|
* will fail.
|
|
*/
|
|
struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir)
|
|
{
|
|
struct inode *key = d_inode(dir);
|
|
struct inode *trap;
|
|
|
|
if (!d_is_dir(dir))
|
|
return ERR_PTR(-ENOTDIR);
|
|
|
|
trap = iget5_locked(sb, (unsigned long) key, ovl_inode_test,
|
|
ovl_inode_set, key);
|
|
if (!trap)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
if (!(trap->i_state & I_NEW)) {
|
|
/* Conflicting layer roots? */
|
|
iput(trap);
|
|
return ERR_PTR(-ELOOP);
|
|
}
|
|
|
|
trap->i_mode = S_IFDIR;
|
|
trap->i_flags = S_DEAD;
|
|
unlock_new_inode(trap);
|
|
|
|
return trap;
|
|
}
|
|
|
|
/*
|
|
* Does overlay inode need to be hashed by lower inode?
|
|
*/
|
|
static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
|
|
struct dentry *lower, bool index)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
|
|
/* No, if pure upper */
|
|
if (!lower)
|
|
return false;
|
|
|
|
/* Yes, if already indexed */
|
|
if (index)
|
|
return true;
|
|
|
|
/* Yes, if won't be copied up */
|
|
if (!ovl_upper_mnt(ofs))
|
|
return true;
|
|
|
|
/* No, if lower hardlink is or will be broken on copy up */
|
|
if ((upper || !ovl_indexdir(sb)) &&
|
|
!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
|
|
return false;
|
|
|
|
/* No, if non-indexed upper with NFS export */
|
|
if (sb->s_export_op && upper)
|
|
return false;
|
|
|
|
/* Otherwise, hash by lower inode for fsnotify */
|
|
return true;
|
|
}
|
|
|
|
static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode,
|
|
struct inode *key)
|
|
{
|
|
return newinode ? inode_insert5(newinode, (unsigned long) key,
|
|
ovl_inode_test, ovl_inode_set, key) :
|
|
iget5_locked(sb, (unsigned long) key,
|
|
ovl_inode_test, ovl_inode_set, key);
|
|
}
|
|
|
|
struct inode *ovl_get_inode(struct super_block *sb,
|
|
struct ovl_inode_params *oip)
|
|
{
|
|
struct ovl_fs *ofs = OVL_FS(sb);
|
|
struct dentry *upperdentry = oip->upperdentry;
|
|
struct ovl_path *lowerpath = oip->lowerpath;
|
|
struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
|
|
struct inode *inode;
|
|
struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
|
|
struct path realpath = {
|
|
.dentry = upperdentry ?: lowerdentry,
|
|
.mnt = upperdentry ? ovl_upper_mnt(ofs) : lowerpath->layer->mnt,
|
|
};
|
|
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
|
|
oip->index);
|
|
int fsid = bylower ? lowerpath->layer->fsid : 0;
|
|
bool is_dir;
|
|
unsigned long ino = 0;
|
|
int err = oip->newinode ? -EEXIST : -ENOMEM;
|
|
|
|
if (!realinode)
|
|
realinode = d_inode(lowerdentry);
|
|
|
|
/*
|
|
* Copy up origin (lower) may exist for non-indexed upper, but we must
|
|
* not use lower as hash key if this is a broken hardlink.
|
|
*/
|
|
is_dir = S_ISDIR(realinode->i_mode);
|
|
if (upperdentry || bylower) {
|
|
struct inode *key = d_inode(bylower ? lowerdentry :
|
|
upperdentry);
|
|
unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
|
|
|
|
inode = ovl_iget5(sb, oip->newinode, key);
|
|
if (!inode)
|
|
goto out_err;
|
|
if (!(inode->i_state & I_NEW)) {
|
|
/*
|
|
* Verify that the underlying files stored in the inode
|
|
* match those in the dentry.
|
|
*/
|
|
if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
|
|
true)) {
|
|
iput(inode);
|
|
err = -ESTALE;
|
|
goto out_err;
|
|
}
|
|
|
|
dput(upperdentry);
|
|
kfree(oip->redirect);
|
|
goto out;
|
|
}
|
|
|
|
/* Recalculate nlink for non-dir due to indexing */
|
|
if (!is_dir)
|
|
nlink = ovl_get_nlink(ofs, lowerdentry, upperdentry,
|
|
nlink);
|
|
set_nlink(inode, nlink);
|
|
ino = key->i_ino;
|
|
} else {
|
|
/* Lower hardlink that will be broken on copy up */
|
|
inode = new_inode(sb);
|
|
if (!inode) {
|
|
err = -ENOMEM;
|
|
goto out_err;
|
|
}
|
|
ino = realinode->i_ino;
|
|
fsid = lowerpath->layer->fsid;
|
|
}
|
|
ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
|
|
ovl_inode_init(inode, oip, ino, fsid);
|
|
|
|
if (upperdentry && ovl_is_impuredir(sb, upperdentry))
|
|
ovl_set_flag(OVL_IMPURE, inode);
|
|
|
|
if (oip->index)
|
|
ovl_set_flag(OVL_INDEX, inode);
|
|
|
|
OVL_I(inode)->redirect = oip->redirect;
|
|
|
|
if (bylower)
|
|
ovl_set_flag(OVL_CONST_INO, inode);
|
|
|
|
/* Check for non-merge dir that may have whiteouts */
|
|
if (is_dir) {
|
|
if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
|
|
ovl_path_check_origin_xattr(ofs, &realpath)) {
|
|
ovl_set_flag(OVL_WHITEOUTS, inode);
|
|
}
|
|
}
|
|
|
|
/* Check for immutable/append-only inode flags in xattr */
|
|
if (upperdentry)
|
|
ovl_check_protattr(inode, upperdentry);
|
|
|
|
if (inode->i_state & I_NEW)
|
|
unlock_new_inode(inode);
|
|
out:
|
|
return inode;
|
|
|
|
out_err:
|
|
pr_warn_ratelimited("failed to get inode (%i)\n", err);
|
|
inode = ERR_PTR(err);
|
|
goto out;
|
|
}
|