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f2fs: check entire encrypted bigname when finding a dentry

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If user has no key under an encrypted dir, fscrypt gives digested dentries.
Previously, when looking up a dentry, f2fs only checks its hash value with
first 4 bytes of the digested dentry, which didn't handle hash collisions fully.
This patch enhances to check entire dentry bytes likewise ext4.

Eric reported how to reproduce this issue by:

 # seq -f "edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
 # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
100000
 # sync
 # echo 3 > /proc/sys/vm/drop_caches
 # keyctl new_session
 # find edir -type f | xargs stat -c %i | sort | uniq | wc -l
99999

Cc: <stable@vger.kernel.org>
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(fixed f2fs_dentry_hash() to work even when the hash is 0)
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jaegeuk Kim 2017-04-24 10:00:08 -07:00 committed by Theodore Ts'o
parent 413d5a9edb
commit 6332cd32c8
4 changed files with 31 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
fs/f2fs/dir.c
View File

@ -130,19 +130,29 @@ struct f2fs_dir_entry *find_target_dentry(struct fscrypt_name *fname,
continue;
}
/* encrypted case */
if (de->hash_code != namehash)
goto not_match;
de_name.name = d->filename[bit_pos];
de_name.len = le16_to_cpu(de->name_len);
/* show encrypted name */
if (fname->hash) {
if (de->hash_code == cpu_to_le32(fname->hash))
goto found;
} else if (de_name.len == name->len &&
de->hash_code == namehash &&
!memcmp(de_name.name, name->name, name->len))
#ifdef CONFIG_F2FS_FS_ENCRYPTION
if (unlikely(!name->name)) {
if (fname->usr_fname->name[0] == '_') {
if (de_name.len >= 16 &&
!memcmp(de_name.name + de_name.len - 16,
fname->crypto_buf.name + 8, 16))
goto found;
goto not_match;
}
name->name = fname->crypto_buf.name;
name->len = fname->crypto_buf.len;
}
#endif
if (de_name.len == name->len &&
!memcmp(de_name.name, name->name, name->len))
goto found;
not_match:
if (max_slots && max_len > *max_slots)
*max_slots = max_len;
max_len = 0;
@ -170,12 +180,7 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
struct f2fs_dir_entry *de = NULL;
bool room = false;
int max_slots;
f2fs_hash_t namehash;
if(fname->hash)
namehash = cpu_to_le32(fname->hash);
else
namehash = f2fs_dentry_hash(&name);
f2fs_hash_t namehash = f2fs_dentry_hash(&name, fname);
nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
nblock = bucket_blocks(level);
@ -542,7 +547,7 @@ int f2fs_add_regular_entry(struct inode *dir, const struct qstr *new_name,
level = 0;
slots = GET_DENTRY_SLOTS(new_name->len);
dentry_hash = f2fs_dentry_hash(new_name);
dentry_hash = f2fs_dentry_hash(new_name, NULL);
current_depth = F2FS_I(dir)->i_current_depth;
if (F2FS_I(dir)->chash == dentry_hash) {

3
fs/f2fs/f2fs.h
View File

@ -2133,7 +2133,8 @@ int sanity_check_ckpt(struct f2fs_sb_info *sbi);
/*
* hash.c
*/
f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info);
f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info,
struct fscrypt_name *fname);
/*
* node.c

7
fs/f2fs/hash.c
View File

@ -70,7 +70,8 @@ static void str2hashbuf(const unsigned char *msg, size_t len,
*buf++ = pad;
}
f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info)
f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info,
struct fscrypt_name *fname)
{
__u32 hash;
f2fs_hash_t f2fs_hash;
@ -79,6 +80,10 @@ f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info)
const unsigned char *name = name_info->name;
size_t len = name_info->len;
/* encrypted bigname case */
if (fname && !fname->disk_name.name)
return cpu_to_le32(fname->hash);
if (is_dot_dotdot(name_info))
return 0;

4
fs/f2fs/inline.c
View File

@ -296,7 +296,7 @@ struct f2fs_dir_entry *find_in_inline_dir(struct inode *dir,
return NULL;
}
namehash = f2fs_dentry_hash(&name);
namehash = f2fs_dentry_hash(&name, fname);
inline_dentry = inline_data_addr(ipage);
@ -533,7 +533,7 @@ int f2fs_add_inline_entry(struct inode *dir, const struct qstr *new_name,
f2fs_wait_on_page_writeback(ipage, NODE, true);
name_hash = f2fs_dentry_hash(new_name);
name_hash = f2fs_dentry_hash(new_name, NULL);
make_dentry_ptr(NULL, &d, (void *)dentry_blk, 2);
f2fs_update_dentry(ino, mode, &d, new_name, name_hash, bit_pos);