OpenCloudOS-Kernel/fs/romfs/super.c

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/* Block- or MTD-based romfs
*
* Copyright © 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* Derived from: ROMFS file system, Linux implementation
*
* Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu>
*
* Using parts of the minix filesystem
* Copyright © 1991, 1992 Linus Torvalds
*
* and parts of the affs filesystem additionally
* Copyright © 1993 Ray Burr
* Copyright © 1996 Hans-Joachim Widmaier
*
* Changes
* Changed for 2.1.19 modules
* Jan 1997 Initial release
* Jun 1997 2.1.43+ changes
* Proper page locking in readpage
* Changed to work with 2.1.45+ fs
* Jul 1997 Fixed follow_link
* 2.1.47
* lookup shouldn't return -ENOENT
* from Horst von Brand:
* fail on wrong checksum
* double unlock_super was possible
* correct namelen for statfs
* spotted by Bill Hawes:
* readlink shouldn't iput()
* Jun 1998 2.1.106 from Avery Pennarun: glibc scandir()
* exposed a problem in readdir
* 2.1.107 code-freeze spellchecker run
* Aug 1998 2.1.118+ VFS changes
* Sep 1998 2.1.122 another VFS change (follow_link)
* Apr 1999 2.2.7 no more EBADF checking in
* lookup/readdir, use ERR_PTR
* Jun 1999 2.3.6 d_alloc_root use changed
* 2.3.9 clean up usage of ENOENT/negative
* dentries in lookup
* clean up page flags setting
* (error, uptodate, locking) in
* in readpage
* use init_special_inode for
* fifos/sockets (and streamline) in
* read_inode, fix _ops table order
* Aug 1999 2.3.16 __initfunc() => __init change
* Oct 1999 2.3.24 page->owner hack obsoleted
* Nov 1999 2.3.27 2.3.25+ page->offset => index change
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/parser.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/statfs.h>
#include <linux/mtd/super.h>
#include <linux/ctype.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/uaccess.h>
romfs: use different way to generate fsid for BLOCK or MTD Commit 8a59f5d25265 ("fs/romfs: return f_fsid for statfs(2)") generates a 64bit id from sb->s_bdev->bd_dev. This is only correct when romfs is defined with CONFIG_ROMFS_ON_BLOCK. If romfs is only defined with CONFIG_ROMFS_ON_MTD, sb->s_bdev is NULL, referencing sb->s_bdev->bd_dev will triger an oops. Richard Weinberger points out that when CONFIG_ROMFS_BACKED_BY_BOTH=y, both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD are defined. Therefore when calling huge_encode_dev() to generate a 64bit id, I use the follow order to choose parameter, - CONFIG_ROMFS_ON_BLOCK defined use sb->s_bdev->bd_dev - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined use sb->s_dev when, - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined leave id as 0 When CONFIG_ROMFS_ON_MTD is defined and sb->s_mtd is not NULL, sb->s_dev is set to a device ID generated by MTD_BLOCK_MAJOR and mtd index, otherwise sb->s_dev is 0. This is a try-best effort to generate a uniq file system ID, if all the above conditions are not meet, f_fsid of this romfs instance will be 0. Generally only one romfs can be built on single MTD block device, this method is enough to identify multiple romfs instances in a computer. Link: http://lkml.kernel.org/r/1482928596-115155-1-git-send-email-colyli@suse.de Signed-off-by: Coly Li <colyli@suse.de> Reported-by: Nong Li <nongli1031@gmail.com> Tested-by: Nong Li <nongli1031@gmail.com> Cc: Richard Weinberger <richard.weinberger@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-25 07:18:46 +08:00
#include <linux/major.h>
#include "internal.h"
static struct kmem_cache *romfs_inode_cachep;
static const umode_t romfs_modemap[8] = {
0, /* hard link */
S_IFDIR | 0644, /* directory */
S_IFREG | 0644, /* regular file */
S_IFLNK | 0777, /* symlink */
S_IFBLK | 0600, /* blockdev */
S_IFCHR | 0600, /* chardev */
S_IFSOCK | 0644, /* socket */
S_IFIFO | 0644 /* FIFO */
};
static const unsigned char romfs_dtype_table[] = {
DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
};
static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
/*
* read a page worth of data from the image
*/
static int romfs_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
loff_t offset, size;
unsigned long fillsize, pos;
void *buf;
int ret;
buf = kmap(page);
if (!buf)
return -ENOMEM;
/* 32 bit warning -- but not for us :) */
offset = page_offset(page);
size = i_size_read(inode);
fillsize = 0;
ret = 0;
if (offset < size) {
size -= offset;
fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
pos = ROMFS_I(inode)->i_dataoffset + offset;
ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
if (ret < 0) {
SetPageError(page);
fillsize = 0;
ret = -EIO;
}
}
if (fillsize < PAGE_SIZE)
memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
if (ret == 0)
SetPageUptodate(page);
flush_dcache_page(page);
kunmap(page);
unlock_page(page);
return ret;
}
static const struct address_space_operations romfs_aops = {
.readpage = romfs_readpage
};
/*
* read the entries from a directory
*/
static int romfs_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *i = file_inode(file);
struct romfs_inode ri;
unsigned long offset, maxoff;
int j, ino, nextfh;
char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
int ret;
maxoff = romfs_maxsize(i->i_sb);
offset = ctx->pos;
if (!offset) {
offset = i->i_ino & ROMFH_MASK;
ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
if (ret < 0)
goto out;
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
}
/* Not really failsafe, but we are read-only... */
for (;;) {
if (!offset || offset >= maxoff) {
offset = maxoff;
ctx->pos = offset;
goto out;
}
ctx->pos = offset;
/* Fetch inode info */
ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
if (ret < 0)
goto out;
j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
sizeof(fsname) - 1);
if (j < 0)
goto out;
ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
if (ret < 0)
goto out;
fsname[j] = '\0';
ino = offset;
nextfh = be32_to_cpu(ri.next);
if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
ino = be32_to_cpu(ri.spec);
if (!dir_emit(ctx, fsname, j, ino,
romfs_dtype_table[nextfh & ROMFH_TYPE]))
goto out;
offset = nextfh & ROMFH_MASK;
}
out:
return 0;
}
/*
* look up an entry in a directory
*/
static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
unsigned long offset, maxoff;
struct inode *inode = NULL;
struct romfs_inode ri;
const char *name; /* got from dentry */
int len, ret;
offset = dir->i_ino & ROMFH_MASK;
ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
if (ret < 0)
goto error;
/* search all the file entries in the list starting from the one
* pointed to by the directory's special data */
maxoff = romfs_maxsize(dir->i_sb);
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
name = dentry->d_name.name;
len = dentry->d_name.len;
for (;;) {
if (!offset || offset >= maxoff)
break;
ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
if (ret < 0)
goto error;
/* try to match the first 16 bytes of name */
ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
len);
if (ret < 0)
goto error;
if (ret == 1) {
/* Hard link handling */
if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
inode = romfs_iget(dir->i_sb, offset);
break;
}
/* next entry */
offset = be32_to_cpu(ri.next) & ROMFH_MASK;
}
return d_splice_alias(inode, dentry);
error:
return ERR_PTR(ret);
}
static const struct file_operations romfs_dir_operations = {
.read = generic_read_dir,
.iterate_shared = romfs_readdir,
.llseek = generic_file_llseek,
};
static const struct inode_operations romfs_dir_inode_operations = {
.lookup = romfs_lookup,
};
/*
* get a romfs inode based on its position in the image (which doubles as the
* inode number)
*/
static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
{
struct romfs_inode_info *inode;
struct romfs_inode ri;
struct inode *i;
unsigned long nlen;
unsigned nextfh;
int ret;
umode_t mode;
/* we might have to traverse a chain of "hard link" file entries to get
* to the actual file */
for (;;) {
ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
if (ret < 0)
goto error;
/* XXX: do romfs_checksum here too (with name) */
nextfh = be32_to_cpu(ri.next);
if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
break;
pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
}
/* determine the length of the filename */
nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
if (IS_ERR_VALUE(nlen))
goto eio;
/* get an inode for this image position */
i = iget_locked(sb, pos);
if (!i)
return ERR_PTR(-ENOMEM);
if (!(i->i_state & I_NEW))
return i;
/* precalculate the data offset */
inode = ROMFS_I(i);
inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
inode->i_dataoffset = pos + inode->i_metasize;
set_nlink(i, 1); /* Hard to decide.. */
i->i_size = be32_to_cpu(ri.size);
i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
/* set up mode and ops */
mode = romfs_modemap[nextfh & ROMFH_TYPE];
switch (nextfh & ROMFH_TYPE) {
case ROMFH_DIR:
i->i_size = ROMFS_I(i)->i_metasize;
i->i_op = &romfs_dir_inode_operations;
i->i_fop = &romfs_dir_operations;
if (nextfh & ROMFH_EXEC)
mode |= S_IXUGO;
break;
case ROMFH_REG:
i->i_fop = &romfs_ro_fops;
i->i_data.a_ops = &romfs_aops;
if (nextfh & ROMFH_EXEC)
mode |= S_IXUGO;
break;
case ROMFH_SYM:
i->i_op = &page_symlink_inode_operations;
inode_nohighmem(i);
i->i_data.a_ops = &romfs_aops;
mode |= S_IRWXUGO;
break;
default:
/* depending on MBZ for sock/fifos */
nextfh = be32_to_cpu(ri.spec);
init_special_inode(i, mode, MKDEV(nextfh >> 16,
nextfh & 0xffff));
break;
}
i->i_mode = mode;
unlock_new_inode(i);
return i;
eio:
ret = -EIO;
error:
pr_err("read error for inode 0x%lx\n", pos);
return ERR_PTR(ret);
}
/*
* allocate a new inode
*/
static struct inode *romfs_alloc_inode(struct super_block *sb)
{
struct romfs_inode_info *inode;
inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
return inode ? &inode->vfs_inode : NULL;
}
/*
* return a spent inode to the slab cache
*/
static void romfs_free_inode(struct inode *inode)
{
kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
}
/*
* get filesystem statistics
*/
static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
romfs: use different way to generate fsid for BLOCK or MTD Commit 8a59f5d25265 ("fs/romfs: return f_fsid for statfs(2)") generates a 64bit id from sb->s_bdev->bd_dev. This is only correct when romfs is defined with CONFIG_ROMFS_ON_BLOCK. If romfs is only defined with CONFIG_ROMFS_ON_MTD, sb->s_bdev is NULL, referencing sb->s_bdev->bd_dev will triger an oops. Richard Weinberger points out that when CONFIG_ROMFS_BACKED_BY_BOTH=y, both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD are defined. Therefore when calling huge_encode_dev() to generate a 64bit id, I use the follow order to choose parameter, - CONFIG_ROMFS_ON_BLOCK defined use sb->s_bdev->bd_dev - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined use sb->s_dev when, - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined leave id as 0 When CONFIG_ROMFS_ON_MTD is defined and sb->s_mtd is not NULL, sb->s_dev is set to a device ID generated by MTD_BLOCK_MAJOR and mtd index, otherwise sb->s_dev is 0. This is a try-best effort to generate a uniq file system ID, if all the above conditions are not meet, f_fsid of this romfs instance will be 0. Generally only one romfs can be built on single MTD block device, this method is enough to identify multiple romfs instances in a computer. Link: http://lkml.kernel.org/r/1482928596-115155-1-git-send-email-colyli@suse.de Signed-off-by: Coly Li <colyli@suse.de> Reported-by: Nong Li <nongli1031@gmail.com> Tested-by: Nong Li <nongli1031@gmail.com> Cc: Richard Weinberger <richard.weinberger@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-25 07:18:46 +08:00
u64 id = 0;
/* When calling huge_encode_dev(),
* use sb->s_bdev->bd_dev when,
* - CONFIG_ROMFS_ON_BLOCK defined
* use sb->s_dev when,
* - CONFIG_ROMFS_ON_BLOCK undefined and
* - CONFIG_ROMFS_ON_MTD defined
* leave id as 0 when,
* - CONFIG_ROMFS_ON_BLOCK undefined and
* - CONFIG_ROMFS_ON_MTD undefined
*/
if (sb->s_bdev)
id = huge_encode_dev(sb->s_bdev->bd_dev);
else if (sb->s_dev)
id = huge_encode_dev(sb->s_dev);
buf->f_type = ROMFS_MAGIC;
buf->f_namelen = ROMFS_MAXFN;
buf->f_bsize = ROMBSIZE;
buf->f_bfree = buf->f_bavail = buf->f_ffree;
buf->f_blocks =
(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
buf->f_fsid.val[0] = (u32)id;
buf->f_fsid.val[1] = (u32)(id >> 32);
return 0;
}
/*
* remounting must involve read-only
*/
static int romfs_remount(struct super_block *sb, int *flags, char *data)
{
fs: push sync_filesystem() down to the file system's remount_fs() Previously, the no-op "mount -o mount /dev/xxx" operation when the file system is already mounted read-write causes an implied, unconditional syncfs(). This seems pretty stupid, and it's certainly documented or guaraunteed to do this, nor is it particularly useful, except in the case where the file system was mounted rw and is getting remounted read-only. However, it's possible that there might be some file systems that are actually depending on this behavior. In most file systems, it's probably fine to only call sync_filesystem() when transitioning from read-write to read-only, and there are some file systems where this is not needed at all (for example, for a pseudo-filesystem or something like romfs). Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: Jan Kara <jack@suse.cz> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Anders Larsen <al@alarsen.net> Cc: Phillip Lougher <phillip@squashfs.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Cc: Petr Vandrovec <petr@vandrovec.name> Cc: xfs@oss.sgi.com Cc: linux-btrfs@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: codalist@coda.cs.cmu.edu Cc: linux-ext4@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: fuse-devel@lists.sourceforge.net Cc: cluster-devel@redhat.com Cc: linux-mtd@lists.infradead.org Cc: jfs-discussion@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: linux-nilfs@vger.kernel.org Cc: linux-ntfs-dev@lists.sourceforge.net Cc: ocfs2-devel@oss.oracle.com Cc: reiserfs-devel@vger.kernel.org
2014-03-13 22:14:33 +08:00
sync_filesystem(sb);
Rename superblock flags (MS_xyz -> SB_xyz) This is a pure automated search-and-replace of the internal kernel superblock flags. The s_flags are now called SB_*, with the names and the values for the moment mirroring the MS_* flags that they're equivalent to. Note how the MS_xyz flags are the ones passed to the mount system call, while the SB_xyz flags are what we then use in sb->s_flags. The script to do this was: # places to look in; re security/*: it generally should *not* be # touched (that stuff parses mount(2) arguments directly), but # there are two places where we really deal with superblock flags. FILES="drivers/mtd drivers/staging/lustre fs ipc mm \ include/linux/fs.h include/uapi/linux/bfs_fs.h \ security/apparmor/apparmorfs.c security/apparmor/include/lib.h" # the list of MS_... constants SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \ DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \ POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \ I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \ ACTIVE NOUSER" SED_PROG= for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done # we want files that contain at least one of MS_..., # with fs/namespace.c and fs/pnode.c excluded. L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c') for f in $L; do sed -i $f $SED_PROG; done Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-28 05:05:09 +08:00
*flags |= SB_RDONLY;
return 0;
}
static const struct super_operations romfs_super_ops = {
.alloc_inode = romfs_alloc_inode,
.free_inode = romfs_free_inode,
.statfs = romfs_statfs,
.remount_fs = romfs_remount,
};
/*
* checksum check on part of a romfs filesystem
*/
static __u32 romfs_checksum(const void *data, int size)
{
const __be32 *ptr = data;
__u32 sum;
sum = 0;
size >>= 2;
while (size > 0) {
sum += be32_to_cpu(*ptr++);
size--;
}
return sum;
}
/*
* fill in the superblock
*/
static int romfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct romfs_super_block *rsb;
struct inode *root;
unsigned long pos, img_size;
const char *storage;
size_t len;
int ret;
#ifdef CONFIG_BLOCK
if (!sb->s_mtd) {
sb_set_blocksize(sb, ROMBSIZE);
} else {
sb->s_blocksize = ROMBSIZE;
sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
}
#endif
sb->s_maxbytes = 0xFFFFFFFF;
sb->s_magic = ROMFS_MAGIC;
Rename superblock flags (MS_xyz -> SB_xyz) This is a pure automated search-and-replace of the internal kernel superblock flags. The s_flags are now called SB_*, with the names and the values for the moment mirroring the MS_* flags that they're equivalent to. Note how the MS_xyz flags are the ones passed to the mount system call, while the SB_xyz flags are what we then use in sb->s_flags. The script to do this was: # places to look in; re security/*: it generally should *not* be # touched (that stuff parses mount(2) arguments directly), but # there are two places where we really deal with superblock flags. FILES="drivers/mtd drivers/staging/lustre fs ipc mm \ include/linux/fs.h include/uapi/linux/bfs_fs.h \ security/apparmor/apparmorfs.c security/apparmor/include/lib.h" # the list of MS_... constants SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \ DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \ POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \ I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \ ACTIVE NOUSER" SED_PROG= for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done # we want files that contain at least one of MS_..., # with fs/namespace.c and fs/pnode.c excluded. L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c') for f in $L; do sed -i $f $SED_PROG; done Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-28 05:05:09 +08:00
sb->s_flags |= SB_RDONLY | SB_NOATIME;
sb->s_op = &romfs_super_ops;
romfs: use different way to generate fsid for BLOCK or MTD Commit 8a59f5d25265 ("fs/romfs: return f_fsid for statfs(2)") generates a 64bit id from sb->s_bdev->bd_dev. This is only correct when romfs is defined with CONFIG_ROMFS_ON_BLOCK. If romfs is only defined with CONFIG_ROMFS_ON_MTD, sb->s_bdev is NULL, referencing sb->s_bdev->bd_dev will triger an oops. Richard Weinberger points out that when CONFIG_ROMFS_BACKED_BY_BOTH=y, both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD are defined. Therefore when calling huge_encode_dev() to generate a 64bit id, I use the follow order to choose parameter, - CONFIG_ROMFS_ON_BLOCK defined use sb->s_bdev->bd_dev - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined use sb->s_dev when, - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined leave id as 0 When CONFIG_ROMFS_ON_MTD is defined and sb->s_mtd is not NULL, sb->s_dev is set to a device ID generated by MTD_BLOCK_MAJOR and mtd index, otherwise sb->s_dev is 0. This is a try-best effort to generate a uniq file system ID, if all the above conditions are not meet, f_fsid of this romfs instance will be 0. Generally only one romfs can be built on single MTD block device, this method is enough to identify multiple romfs instances in a computer. Link: http://lkml.kernel.org/r/1482928596-115155-1-git-send-email-colyli@suse.de Signed-off-by: Coly Li <colyli@suse.de> Reported-by: Nong Li <nongli1031@gmail.com> Tested-by: Nong Li <nongli1031@gmail.com> Cc: Richard Weinberger <richard.weinberger@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-25 07:18:46 +08:00
#ifdef CONFIG_ROMFS_ON_MTD
/* Use same dev ID from the underlying mtdblock device */
if (sb->s_mtd)
sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
#endif
/* read the image superblock and check it */
rsb = kmalloc(512, GFP_KERNEL);
if (!rsb)
return -ENOMEM;
sb->s_fs_info = (void *) 512;
ret = romfs_dev_read(sb, 0, rsb, 512);
if (ret < 0)
goto error_rsb;
img_size = be32_to_cpu(rsb->size);
if (sb->s_mtd && img_size > sb->s_mtd->size)
goto error_rsb_inval;
sb->s_fs_info = (void *) img_size;
if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
img_size < ROMFH_SIZE) {
if (!silent)
pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
sb->s_id);
goto error_rsb_inval;
}
if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
pr_err("bad initial checksum on dev %s.\n", sb->s_id);
goto error_rsb_inval;
}
storage = sb->s_mtd ? "MTD" : "the block layer";
len = strnlen(rsb->name, ROMFS_MAXFN);
if (!silent)
pr_notice("Mounting image '%*.*s' through %s\n",
(unsigned) len, (unsigned) len, rsb->name, storage);
kfree(rsb);
rsb = NULL;
/* find the root directory */
pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
root = romfs_iget(sb, pos);
if (IS_ERR(root))
return PTR_ERR(root);
sb->s_root = d_make_root(root);
if (!sb->s_root)
return -ENOMEM;
return 0;
error_rsb_inval:
ret = -EINVAL;
error_rsb:
kfree(rsb);
return ret;
}
/*
* get a superblock for mounting
*/
static struct dentry *romfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
struct dentry *ret = ERR_PTR(-EINVAL);
#ifdef CONFIG_ROMFS_ON_MTD
ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
if (ret == ERR_PTR(-EINVAL))
ret = mount_bdev(fs_type, flags, dev_name, data,
romfs_fill_super);
#endif
return ret;
}
/*
* destroy a romfs superblock in the appropriate manner
*/
static void romfs_kill_sb(struct super_block *sb)
{
#ifdef CONFIG_ROMFS_ON_MTD
if (sb->s_mtd) {
kill_mtd_super(sb);
return;
}
#endif
#ifdef CONFIG_ROMFS_ON_BLOCK
if (sb->s_bdev) {
kill_block_super(sb);
return;
}
#endif
}
static struct file_system_type romfs_fs_type = {
.owner = THIS_MODULE,
.name = "romfs",
.mount = romfs_mount,
.kill_sb = romfs_kill_sb,
.fs_flags = FS_REQUIRES_DEV,
};
fs: Limit sys_mount to only request filesystem modules. Modify the request_module to prefix the file system type with "fs-" and add aliases to all of the filesystems that can be built as modules to match. A common practice is to build all of the kernel code and leave code that is not commonly needed as modules, with the result that many users are exposed to any bug anywhere in the kernel. Looking for filesystems with a fs- prefix limits the pool of possible modules that can be loaded by mount to just filesystems trivially making things safer with no real cost. Using aliases means user space can control the policy of which filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. This also addresses a rare but unfortunate problem where the filesystem name is not the same as it's module name and module auto-loading would not work. While writing this patch I saw a handful of such cases. The most significant being autofs that lives in the module autofs4. This is relevant to user namespaces because we can reach the request module in get_fs_type() without having any special permissions, and people get uncomfortable when a user specified string (in this case the filesystem type) goes all of the way to request_module. After having looked at this issue I don't think there is any particular reason to perform any filtering or permission checks beyond making it clear in the module request that we want a filesystem module. The common pattern in the kernel is to call request_module() without regards to the users permissions. In general all a filesystem module does once loaded is call register_filesystem() and go to sleep. Which means there is not much attack surface exposed by loading a filesytem module unless the filesystem is mounted. In a user namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT, which most filesystems do not set today. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Reported-by: Kees Cook <keescook@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-03-03 11:39:14 +08:00
MODULE_ALIAS_FS("romfs");
/*
* inode storage initialiser
*/
static void romfs_i_init_once(void *_inode)
{
struct romfs_inode_info *inode = _inode;
inode_init_once(&inode->vfs_inode);
}
/*
* romfs module initialisation
*/
static int __init init_romfs_fs(void)
{
int ret;
pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
romfs_inode_cachep =
kmem_cache_create("romfs_i",
sizeof(struct romfs_inode_info), 0,
2016-01-15 07:18:21 +08:00
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
SLAB_ACCOUNT, romfs_i_init_once);
if (!romfs_inode_cachep) {
pr_err("Failed to initialise inode cache\n");
return -ENOMEM;
}
ret = register_filesystem(&romfs_fs_type);
if (ret) {
pr_err("Failed to register filesystem\n");
goto error_register;
}
return 0;
error_register:
kmem_cache_destroy(romfs_inode_cachep);
return ret;
}
/*
* romfs module removal
*/
static void __exit exit_romfs_fs(void)
{
unregister_filesystem(&romfs_fs_type);
/*
* Make sure all delayed rcu free inodes are flushed before we
* destroy cache.
*/
rcu_barrier();
kmem_cache_destroy(romfs_inode_cachep);
}
module_init(init_romfs_fs);
module_exit(exit_romfs_fs);
MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */