linux-stable/fs/erofs/super.c
Gao Xiang bde545295b erofs: fix shift-out-of-bounds of blkszbits
syzbot generated a crafted bitszbits which can be shifted
out-of-bounds[1]. So directly print unsupported blkszbits
instead of blksize.

[1] https://lore.kernel.org/r/000000000000c72ddd05b9444d2f@google.com

Link: https://lore.kernel.org/r/20210120013016.14071-1-hsiangkao@aol.com
Reported-by: syzbot+c68f467cd7c45860e8d4@syzkaller.appspotmail.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
2021-02-11 11:54:57 +08:00

610 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* https://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
#include <linux/module.h>
#include <linux/buffer_head.h>
#include <linux/statfs.h>
#include <linux/parser.h>
#include <linux/seq_file.h>
#include <linux/crc32c.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include "xattr.h"
#define CREATE_TRACE_POINTS
#include <trace/events/erofs.h>
static struct kmem_cache *erofs_inode_cachep __read_mostly;
void _erofs_err(struct super_block *sb, const char *function,
const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("(device %s): %s: %pV", sb->s_id, function, &vaf);
va_end(args);
}
void _erofs_info(struct super_block *sb, const char *function,
const char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_info("(device %s): %pV", sb->s_id, &vaf);
va_end(args);
}
static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
{
struct erofs_super_block *dsb;
u32 expected_crc, crc;
dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET,
EROFS_BLKSIZ - EROFS_SUPER_OFFSET, GFP_KERNEL);
if (!dsb)
return -ENOMEM;
expected_crc = le32_to_cpu(dsb->checksum);
dsb->checksum = 0;
/* to allow for x86 boot sectors and other oddities. */
crc = crc32c(~0, dsb, EROFS_BLKSIZ - EROFS_SUPER_OFFSET);
kfree(dsb);
if (crc != expected_crc) {
erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
crc, expected_crc);
return -EBADMSG;
}
return 0;
}
static void erofs_inode_init_once(void *ptr)
{
struct erofs_inode *vi = ptr;
inode_init_once(&vi->vfs_inode);
}
static struct inode *erofs_alloc_inode(struct super_block *sb)
{
struct erofs_inode *vi =
kmem_cache_alloc(erofs_inode_cachep, GFP_KERNEL);
if (!vi)
return NULL;
/* zero out everything except vfs_inode */
memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
return &vi->vfs_inode;
}
static void erofs_free_inode(struct inode *inode)
{
struct erofs_inode *vi = EROFS_I(inode);
/* be careful of RCU symlink path */
if (inode->i_op == &erofs_fast_symlink_iops)
kfree(inode->i_link);
kfree(vi->xattr_shared_xattrs);
kmem_cache_free(erofs_inode_cachep, vi);
}
static bool check_layout_compatibility(struct super_block *sb,
struct erofs_super_block *dsb)
{
const unsigned int feature = le32_to_cpu(dsb->feature_incompat);
EROFS_SB(sb)->feature_incompat = feature;
/* check if current kernel meets all mandatory requirements */
if (feature & (~EROFS_ALL_FEATURE_INCOMPAT)) {
erofs_err(sb,
"unidentified incompatible feature %x, please upgrade kernel version",
feature & ~EROFS_ALL_FEATURE_INCOMPAT);
return false;
}
return true;
}
static int erofs_read_superblock(struct super_block *sb)
{
struct erofs_sb_info *sbi;
struct page *page;
struct erofs_super_block *dsb;
unsigned int blkszbits;
void *data;
int ret;
page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
if (IS_ERR(page)) {
erofs_err(sb, "cannot read erofs superblock");
return PTR_ERR(page);
}
sbi = EROFS_SB(sb);
data = kmap(page);
dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);
ret = -EINVAL;
if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
erofs_err(sb, "cannot find valid erofs superblock");
goto out;
}
sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
ret = erofs_superblock_csum_verify(sb, data);
if (ret)
goto out;
}
blkszbits = dsb->blkszbits;
/* 9(512 bytes) + LOG_SECTORS_PER_BLOCK == LOG_BLOCK_SIZE */
if (blkszbits != LOG_BLOCK_SIZE) {
erofs_err(sb, "blkszbits %u isn't supported on this platform",
blkszbits);
goto out;
}
if (!check_layout_compatibility(sb, dsb))
goto out;
sbi->blocks = le32_to_cpu(dsb->blocks);
sbi->meta_blkaddr = le32_to_cpu(dsb->meta_blkaddr);
#ifdef CONFIG_EROFS_FS_XATTR
sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
#endif
sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
sbi->root_nid = le16_to_cpu(dsb->root_nid);
sbi->inos = le64_to_cpu(dsb->inos);
sbi->build_time = le64_to_cpu(dsb->build_time);
sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
memcpy(&sb->s_uuid, dsb->uuid, sizeof(dsb->uuid));
ret = strscpy(sbi->volume_name, dsb->volume_name,
sizeof(dsb->volume_name));
if (ret < 0) { /* -E2BIG */
erofs_err(sb, "bad volume name without NIL terminator");
ret = -EFSCORRUPTED;
goto out;
}
ret = 0;
out:
kunmap(page);
put_page(page);
return ret;
}
/* set up default EROFS parameters */
static void erofs_default_options(struct erofs_fs_context *ctx)
{
#ifdef CONFIG_EROFS_FS_ZIP
ctx->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
ctx->max_sync_decompress_pages = 3;
#endif
#ifdef CONFIG_EROFS_FS_XATTR
set_opt(ctx, XATTR_USER);
#endif
#ifdef CONFIG_EROFS_FS_POSIX_ACL
set_opt(ctx, POSIX_ACL);
#endif
}
enum {
Opt_user_xattr,
Opt_acl,
Opt_cache_strategy,
Opt_err
};
static const struct constant_table erofs_param_cache_strategy[] = {
{"disabled", EROFS_ZIP_CACHE_DISABLED},
{"readahead", EROFS_ZIP_CACHE_READAHEAD},
{"readaround", EROFS_ZIP_CACHE_READAROUND},
{}
};
static const struct fs_parameter_spec erofs_fs_parameters[] = {
fsparam_flag_no("user_xattr", Opt_user_xattr),
fsparam_flag_no("acl", Opt_acl),
fsparam_enum("cache_strategy", Opt_cache_strategy,
erofs_param_cache_strategy),
{}
};
static int erofs_fc_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{
struct erofs_fs_context *ctx __maybe_unused = fc->fs_private;
struct fs_parse_result result;
int opt;
opt = fs_parse(fc, erofs_fs_parameters, param, &result);
if (opt < 0)
return opt;
switch (opt) {
case Opt_user_xattr:
#ifdef CONFIG_EROFS_FS_XATTR
if (result.boolean)
set_opt(ctx, XATTR_USER);
else
clear_opt(ctx, XATTR_USER);
#else
errorfc(fc, "{,no}user_xattr options not supported");
#endif
break;
case Opt_acl:
#ifdef CONFIG_EROFS_FS_POSIX_ACL
if (result.boolean)
set_opt(ctx, POSIX_ACL);
else
clear_opt(ctx, POSIX_ACL);
#else
errorfc(fc, "{,no}acl options not supported");
#endif
break;
case Opt_cache_strategy:
#ifdef CONFIG_EROFS_FS_ZIP
ctx->cache_strategy = result.uint_32;
#else
errorfc(fc, "compression not supported, cache_strategy ignored");
#endif
break;
default:
return -ENOPARAM;
}
return 0;
}
#ifdef CONFIG_EROFS_FS_ZIP
static const struct address_space_operations managed_cache_aops;
static int erofs_managed_cache_releasepage(struct page *page, gfp_t gfp_mask)
{
int ret = 1; /* 0 - busy */
struct address_space *const mapping = page->mapping;
DBG_BUGON(!PageLocked(page));
DBG_BUGON(mapping->a_ops != &managed_cache_aops);
if (PagePrivate(page))
ret = erofs_try_to_free_cached_page(mapping, page);
return ret;
}
static void erofs_managed_cache_invalidatepage(struct page *page,
unsigned int offset,
unsigned int length)
{
const unsigned int stop = length + offset;
DBG_BUGON(!PageLocked(page));
/* Check for potential overflow in debug mode */
DBG_BUGON(stop > PAGE_SIZE || stop < length);
if (offset == 0 && stop == PAGE_SIZE)
while (!erofs_managed_cache_releasepage(page, GFP_NOFS))
cond_resched();
}
static const struct address_space_operations managed_cache_aops = {
.releasepage = erofs_managed_cache_releasepage,
.invalidatepage = erofs_managed_cache_invalidatepage,
};
static int erofs_init_managed_cache(struct super_block *sb)
{
struct erofs_sb_info *const sbi = EROFS_SB(sb);
struct inode *const inode = new_inode(sb);
if (!inode)
return -ENOMEM;
set_nlink(inode, 1);
inode->i_size = OFFSET_MAX;
inode->i_mapping->a_ops = &managed_cache_aops;
mapping_set_gfp_mask(inode->i_mapping,
GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
sbi->managed_cache = inode;
return 0;
}
#else
static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
#endif
static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct inode *inode;
struct erofs_sb_info *sbi;
struct erofs_fs_context *ctx = fc->fs_private;
int err;
sb->s_magic = EROFS_SUPER_MAGIC;
if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
erofs_err(sb, "failed to set erofs blksize");
return -EINVAL;
}
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sb->s_fs_info = sbi;
err = erofs_read_superblock(sb);
if (err)
return err;
sb->s_flags |= SB_RDONLY | SB_NOATIME;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_time_gran = 1;
sb->s_op = &erofs_sops;
sb->s_xattr = erofs_xattr_handlers;
if (test_opt(ctx, POSIX_ACL))
sb->s_flags |= SB_POSIXACL;
else
sb->s_flags &= ~SB_POSIXACL;
sbi->ctx = *ctx;
#ifdef CONFIG_EROFS_FS_ZIP
xa_init(&sbi->managed_pslots);
#endif
/* get the root inode */
inode = erofs_iget(sb, ROOT_NID(sbi), true);
if (IS_ERR(inode))
return PTR_ERR(inode);
if (!S_ISDIR(inode->i_mode)) {
erofs_err(sb, "rootino(nid %llu) is not a directory(i_mode %o)",
ROOT_NID(sbi), inode->i_mode);
iput(inode);
return -EINVAL;
}
sb->s_root = d_make_root(inode);
if (!sb->s_root)
return -ENOMEM;
erofs_shrinker_register(sb);
/* sb->s_umount is already locked, SB_ACTIVE and SB_BORN are not set */
err = erofs_init_managed_cache(sb);
if (err)
return err;
erofs_info(sb, "mounted with root inode @ nid %llu.", ROOT_NID(sbi));
return 0;
}
static int erofs_fc_get_tree(struct fs_context *fc)
{
return get_tree_bdev(fc, erofs_fc_fill_super);
}
static int erofs_fc_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct erofs_fs_context *ctx = fc->fs_private;
DBG_BUGON(!sb_rdonly(sb));
if (test_opt(ctx, POSIX_ACL))
fc->sb_flags |= SB_POSIXACL;
else
fc->sb_flags &= ~SB_POSIXACL;
sbi->ctx = *ctx;
fc->sb_flags |= SB_RDONLY;
return 0;
}
static void erofs_fc_free(struct fs_context *fc)
{
kfree(fc->fs_private);
}
static const struct fs_context_operations erofs_context_ops = {
.parse_param = erofs_fc_parse_param,
.get_tree = erofs_fc_get_tree,
.reconfigure = erofs_fc_reconfigure,
.free = erofs_fc_free,
};
static int erofs_init_fs_context(struct fs_context *fc)
{
fc->fs_private = kzalloc(sizeof(struct erofs_fs_context), GFP_KERNEL);
if (!fc->fs_private)
return -ENOMEM;
/* set default mount options */
erofs_default_options(fc->fs_private);
fc->ops = &erofs_context_ops;
return 0;
}
/*
* could be triggered after deactivate_locked_super()
* is called, thus including umount and failed to initialize.
*/
static void erofs_kill_sb(struct super_block *sb)
{
struct erofs_sb_info *sbi;
WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
kill_block_super(sb);
sbi = EROFS_SB(sb);
if (!sbi)
return;
kfree(sbi);
sb->s_fs_info = NULL;
}
/* called when ->s_root is non-NULL */
static void erofs_put_super(struct super_block *sb)
{
struct erofs_sb_info *const sbi = EROFS_SB(sb);
DBG_BUGON(!sbi);
erofs_shrinker_unregister(sb);
#ifdef CONFIG_EROFS_FS_ZIP
iput(sbi->managed_cache);
sbi->managed_cache = NULL;
#endif
}
static struct file_system_type erofs_fs_type = {
.owner = THIS_MODULE,
.name = "erofs",
.init_fs_context = erofs_init_fs_context,
.kill_sb = erofs_kill_sb,
.fs_flags = FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("erofs");
static int __init erofs_module_init(void)
{
int err;
erofs_check_ondisk_layout_definitions();
erofs_inode_cachep = kmem_cache_create("erofs_inode",
sizeof(struct erofs_inode), 0,
SLAB_RECLAIM_ACCOUNT,
erofs_inode_init_once);
if (!erofs_inode_cachep) {
err = -ENOMEM;
goto icache_err;
}
err = erofs_init_shrinker();
if (err)
goto shrinker_err;
err = z_erofs_init_zip_subsystem();
if (err)
goto zip_err;
err = register_filesystem(&erofs_fs_type);
if (err)
goto fs_err;
return 0;
fs_err:
z_erofs_exit_zip_subsystem();
zip_err:
erofs_exit_shrinker();
shrinker_err:
kmem_cache_destroy(erofs_inode_cachep);
icache_err:
return err;
}
static void __exit erofs_module_exit(void)
{
unregister_filesystem(&erofs_fs_type);
z_erofs_exit_zip_subsystem();
erofs_exit_shrinker();
/* Ensure all RCU free inodes are safe before cache is destroyed. */
rcu_barrier();
kmem_cache_destroy(erofs_inode_cachep);
}
/* get filesystem statistics */
static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
struct erofs_sb_info *sbi = EROFS_SB(sb);
u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
buf->f_type = sb->s_magic;
buf->f_bsize = EROFS_BLKSIZ;
buf->f_blocks = sbi->blocks;
buf->f_bfree = buf->f_bavail = 0;
buf->f_files = ULLONG_MAX;
buf->f_ffree = ULLONG_MAX - sbi->inos;
buf->f_namelen = EROFS_NAME_LEN;
buf->f_fsid = u64_to_fsid(id);
return 0;
}
static int erofs_show_options(struct seq_file *seq, struct dentry *root)
{
struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);
struct erofs_fs_context *ctx __maybe_unused = &sbi->ctx;
#ifdef CONFIG_EROFS_FS_XATTR
if (test_opt(ctx, XATTR_USER))
seq_puts(seq, ",user_xattr");
else
seq_puts(seq, ",nouser_xattr");
#endif
#ifdef CONFIG_EROFS_FS_POSIX_ACL
if (test_opt(ctx, POSIX_ACL))
seq_puts(seq, ",acl");
else
seq_puts(seq, ",noacl");
#endif
#ifdef CONFIG_EROFS_FS_ZIP
if (ctx->cache_strategy == EROFS_ZIP_CACHE_DISABLED)
seq_puts(seq, ",cache_strategy=disabled");
else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAHEAD)
seq_puts(seq, ",cache_strategy=readahead");
else if (ctx->cache_strategy == EROFS_ZIP_CACHE_READAROUND)
seq_puts(seq, ",cache_strategy=readaround");
#endif
return 0;
}
const struct super_operations erofs_sops = {
.put_super = erofs_put_super,
.alloc_inode = erofs_alloc_inode,
.free_inode = erofs_free_inode,
.statfs = erofs_statfs,
.show_options = erofs_show_options,
};
module_init(erofs_module_init);
module_exit(erofs_module_exit);
MODULE_DESCRIPTION("Enhanced ROM File System");
MODULE_AUTHOR("Gao Xiang, Chao Yu, Miao Xie, CONSUMER BG, HUAWEI Inc.");
MODULE_LICENSE("GPL");