From 6332cd32c8290a80e929fc044dc5bdba77396e33 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Mon, 24 Apr 2017 10:00:08 -0700 Subject: [PATCH] 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: Reported-by: Eric Biggers Signed-off-by: Jaegeuk Kim (fixed f2fs_dentry_hash() to work even when the hash is 0) Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o --- 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 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) { diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 0a6e115562f6..05d7e2cefc56 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -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 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 e32a9e527968..fa729ff6b2f9 100644 --- a/fs/f2fs/inline.c +++ b/fs/f2fs/inline.c @@ -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); -- 2.20.1