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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/hash.c
parent413d5a9edbb45eec4dbb1904fe689b561ea5d143 (diff)
downloadlinux-6332cd32c8290a80e929fc044dc5bdba77396e33.tar.bz2
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/hash.c')
-rw-r--r--fs/f2fs/hash.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index 71b7206c431e..eb2e031ea887 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -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;