From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [PATCH 1/6] f2fs: check entire encrypted bigname when finding a dentry Date: Mon, 24 Apr 2017 17:10:23 -0700 Message-ID: <20170425001023.GA4983@jaegeuk.local> References: <20170424170013.85175-1-ebiggers3@gmail.com> <20170424170013.85175-2-ebiggers3@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fscrypt@vger.kernel.org, "Theodore Y . Ts'o" , linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org, linux-mtd@lists.infradead.org, Gwendal Grignou , hashimoto@chromium.org, kinaba@chromium.org, stable@vger.kernel.org, Eric Biggers To: Eric Biggers Return-path: Content-Disposition: inline In-Reply-To: <20170424170013.85175-2-ebiggers3@gmail.com> Sender: stable-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi Eric, This looks good to me. I'll drop it from my tree, so please move forward through fscrypt. Thanks, On 04/24, Eric Biggers wrote: > From: Jaegeuk Kim > > 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 > --- > 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