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authorJaegeuk Kim <jaegeuk@kernel.org>2017-04-24 10:00:08 -0700
committerTheodore Ts'o <tytso@mit.edu>2017-05-04 11:44:35 -0400
commit6332cd32c8290a80e929fc044dc5bdba77396e33 (patch)
tree24f76cfe6d3dddfd9aa15189ee6445584f71fee6 /fs/f2fs/dir.c
parent413d5a9edbb45eec4dbb1904fe689b561ea5d143 (diff)
f2fs: check entire encrypted bigname when finding a dentry
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>
Diffstat (limited to 'fs/f2fs/dir.c')
-rw-r--r--fs/f2fs/dir.c37
1 files changed, 21 insertions, 16 deletions
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 8d5c62b07b28..f32e23eaf8dc 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -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) {