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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
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4
fs/f2fs/inline.c
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@@ -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);