kernel/git/stable/linux.git/fs/ext4/dir.c, branch linux-4.4.y

ext4: fix potential infinite loop in ext4_dx_readdir()

2021-10-06T08:22:25+00:00

commit 42cb447410d024e9d54139ae9c21ea132a8c384c upstream. When ext4_htree_fill_tree() fails, ext4_dx_readdir() can run into an infinite loop since if info->last_pos != ctx->pos this will reset the directory scan and reread the failing entry. For example: 1. a dx_dir which has 3 block, block 0 as dx_root block, block 1/2 as leaf block which own the ext4_dir_entry_2 2. block 1 read ok and call_filldir which will fill the dirent and update the ctx->pos 3. block 2 read fail, but we has already fill some dirent, so we will return back to userspace will a positive return val(see ksys_getdents64) 4. the second ext4_dx_readdir will reset the world since info->last_pos != ctx->pos, and will also init the curr_hash which pos to block 1 5. So we will read block1 too, and once block2 still read fail, we can only fill one dirent because the hash of the entry in block1(besides the last one) won't greater than curr_hash 6. this time, we forget update last_pos too since the read for block2 will fail, and since we has got the one entry, ksys_getdents64 can return success 7. Latter we will trapped in a loop with step 4~6 Cc: stable@kernel.org Signed-off-by: yangerkun Reviewed-by: Jan Kara Signed-off-by: Theodore Ts'o Link: https://lore.kernel.org/r/20210914111415.3921954-1-yangerkun@huawei.com Signed-off-by: Greg Kroah-Hartman

ext4: fix checksum errors with indexed dirs

2020-02-28T14:38:48+00:00

commit 48a34311953d921235f4d7bbd2111690d2e469cf upstream. DIR_INDEX has been introduced as a compat ext4 feature. That means that even kernels / tools that don't understand the feature may modify the filesystem. This works because for kernels not understanding indexed dir format, internal htree nodes appear just as empty directory entries. Index dir aware kernels then check the htree structure is still consistent before using the data. This all worked reasonably well until metadata checksums were introduced. The problem is that these effectively made DIR_INDEX only ro-compatible because internal htree nodes store checksums in a different place than normal directory blocks. Thus any modification ignorant to DIR_INDEX (or just clearing EXT4_INDEX_FL from the inode) will effectively cause checksum mismatch and trigger kernel errors. So we have to be more careful when dealing with indexed directories on filesystems with checksumming enabled. 1) We just disallow loading any directory inodes with EXT4_INDEX_FL when DIR_INDEX is not enabled. This is harsh but it should be very rare (it means someone disabled DIR_INDEX on existing filesystem and didn't run e2fsck), e2fsck can fix the problem, and we don't want to answer the difficult question: "Should we rather corrupt the directory more or should we ignore that DIR_INDEX feature is not set?" 2) When we find out htree structure is corrupted (but the filesystem and the directory should in support htrees), we continue just ignoring htree information for reading but we refuse to add new entries to the directory to avoid corrupting it more. Link: https://lore.kernel.org/r/20200210144316.22081-1-jack@suse.cz Fixes: dbe89444042a ("ext4: Calculate and verify checksums for htree nodes") Reviewed-by: Andreas Dilger Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman

ext4: check for directory entries too close to block end

2020-01-04T12:34:22+00:00

commit 109ba779d6cca2d519c5dd624a3276d03e21948e upstream. ext4_check_dir_entry() currently does not catch a case when a directory entry ends so close to the block end that the header of the next directory entry would not fit in the remaining space. This can lead to directory iteration code trying to access address beyond end of current buffer head leading to oops. CC: stable@vger.kernel.org Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20191202170213.4761-3-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

ext4: avoid divide by zero fault when deleting corrupted inline directories

2018-09-29T10:08:53+00:00

commit 4d982e25d0bdc83d8c64e66fdeca0b89240b3b85 upstream. A specially crafted file system can trick empty_inline_dir() into reading past the last valid entry in a inline directory, and then run into the end of xattr marker. This will trigger a divide by zero fault. Fix this by using the size of the inline directory instead of dir->i_size. Also clean up error reporting in __ext4_check_dir_entry so that the message is clearer and more understandable --- and avoids the division by zero trap if the size passed in is zero. (I'm not sure why we coded it that way in the first place; printing offset % size is actually more confusing and less useful.) https://bugzilla.kernel.org/show_bug.cgi?id=200933 Signed-off-by: Theodore Ts'o Reported-by: Wen Xu Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

ext4 crypto: revalidate dentry after adding or removing the key

2017-05-08T05:46:02+00:00

commit 28b4c263961c47da84ed8b5be0b5116bad1133eb upstream. Add a validation check for dentries for encrypted directory to make sure we're not caching stale data after a key has been added or removed. Also check to make sure that status of the encryption key is updated when readdir(2) is executed. Signed-off-by: Theodore Ts'o Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

ext4: clean up feature test macros with predicate functions

2015-10-17T20:18:43+00:00

Create separate predicate functions to test/set/clear feature flags, thereby replacing the wordy old macros. Furthermore, clean out the places where we open-coded feature tests. Signed-off-by: Darrick J. Wong

ext4: call out CRC and corruption errors with specific error codes

2015-10-17T20:16:04+00:00

Instead of overloading EIO for CRC errors and corrupt structures, return the same error codes that XFS returns for the same issues. Signed-off-by: Darrick J. Wong Signed-off-by: Theodore Ts'o

ext4 crypto: make sure the encryption info is initialized on opendir(2)

2015-05-31T17:34:57+00:00

Signed-off-by: Theodore Ts'o

ext4 crypto: use per-inode tfm structure

2015-05-31T17:34:22+00:00

As suggested by Herbert Xu, we shouldn't allocate a new tfm each time we read or write a page. Instead we can use a single tfm hanging off the inode's crypt_info structure for all of our encryption needs for that inode, since the tfm can be used by multiple crypto requests in parallel. Also use cmpxchg() to avoid races that could result in crypt_info structure getting doubly allocated or doubly freed. Signed-off-by: Theodore Ts'o

ext4 crypto: reorganize how we store keys in the inode

2015-05-18T17:17:47+00:00

This is a pretty massive patch which does a number of different things: 1) The per-inode encryption information is now stored in an allocated data structure, ext4_crypt_info, instead of directly in the node. This reduces the size usage of an in-memory inode when it is not using encryption. 2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode encryption structure instead. This remove an unnecessary memory allocation and free for the fname_crypto_ctx as well as allowing us to reuse the ctfm in a directory for multiple lookups and file creations. 3) We also cache the inode's policy information in the ext4_crypt_info structure so we don't have to continually read it out of the extended attributes. 4) We now keep the keyring key in the inode's encryption structure instead of releasing it after we are done using it to derive the per-inode key. This allows us to test to see if the key has been revoked; if it has, we prevent the use of the derived key and free it. 5) When an inode is released (or when the derived key is freed), we will use memset_explicit() to zero out the derived key, so it's not left hanging around in memory. This implies that when a user logs out, it is important to first revoke the key, and then unlink it, and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to release any decrypted pages and dcache entries from the system caches. 6) All this, and we also shrink the number of lines of code by around 100. :-) Signed-off-by: Theodore Ts'o