From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
(fixed f2fs_dentry_hash() to work even when the hash is 0)
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/f2fs/dir.c | 37 +++++++++++++++++++++----------------
fs/f2fs/f2fs.h | 3 ++-
fs/f2fs/hash.c | 7 ++++++-
fs/f2fs/inline.c | 4 ++--
4 files changed, 31 insertions(+), 20 deletions(-)
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index c143dffcae6e..374e4b8f9b70 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);
@@ -527,7 +532,7 @@ 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) {
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 562db8989a4e..5bc232e21a6e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2145,7 +2145,8 @@ 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
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;
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 0ccdefe9fdba..e4c527c4e7d0 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -298,7 +298,7 @@ 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_inline(NULL, &d, dentry_blk);
f2fs_update_dentry(ino, mode, &d, new_name, name_hash, bit_pos);
--
2.12.2.816.g2cccc81164-goog