kernel.git/fs/f2fs/dir.c, branch linux-4.4.y

f2fs crypto: avoid unneeded memory allocation in ->readdir

2020-11-10T09:22:12Z

commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b upstream. When decrypting dirents in ->readdir, fscrypt_fname_disk_to_usr won't change content of original encrypted dirent, we don't need to allocate additional buffer for storing mirror of it, so get rid of it. [This backport fixes a regression in 4.4-stable caused by commit 11a6e8f89521 ("f2fs: check memory boundary by insane namelen"), which depended on this missing commit. This bad backport broke f2fs encryption because it moved the incrementing of 'bit_pos' to earlier in f2fs_fill_dentries() without accounting for it being used in the encrypted dir case. This caused readdir() on encrypted directories to start failing. Tested with 'kvm-xfstests -c f2fs -g encrypt'.] Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

f2fs: check if file namelen exceeds max value

2020-08-21T08:52:53Z

[ Upstream commit 720db068634c91553a8e1d9a0fcd8c7050e06d2b ] Dentry bitmap is not enough to detect incorrect dentries. So this patch also checks the namelen value of a dentry. Signed-off-by: Gong Chen Signed-off-by: Sheng Yong Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: check memory boundary by insane namelen

2020-08-21T08:52:53Z

[ Upstream commit 4e240d1bab1ead280ddf5eb05058dba6bbd57d10 ] If namelen is corrupted to have very long value, fill_dentries can copy wrong memory area. Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: fix to convert inline directory correctly

2019-01-26T08:42:45Z

With below serials, we will lose parts of dirents: 1) mount f2fs with inline_dentry option 2) echo 1 > /sys/fs/f2fs/sdX/dir_level 3) mkdir dir 4) touch 180 files named [1-180] in dir 5) touch 181 in dir 6) echo 3 > /proc/sys/vm/drop_caches 7) ll dir ls: cannot access 2: No such file or directory ls: cannot access 4: No such file or directory ls: cannot access 5: No such file or directory ls: cannot access 6: No such file or directory ls: cannot access 8: No such file or directory ls: cannot access 9: No such file or directory ... total 360 drwxr-xr-x 2 root root 4096 Feb 19 15:12 ./ drwxr-xr-x 3 root root 4096 Feb 19 15:11 ../ -rw-r--r-- 1 root root 0 Feb 19 15:12 1 -rw-r--r-- 1 root root 0 Feb 19 15:12 10 -rw-r--r-- 1 root root 0 Feb 19 15:12 100 -????????? ? ? ? ? ? 101 -????????? ? ? ? ? ? 102 -????????? ? ? ? ? ? 103 ... The reason is: when doing the inline dir conversion, we didn't consider that directory has hierarchical hash structure which can be configured through sysfs interface 'dir_level'. By default, dir_level of directory inode is 0, it means we have one bucket in hash table located in first level, all dirents will be hashed in this bucket, so it has no problem for us to do the duplication simply between inline dentry page and converted normal dentry page. However, if we configured dir_level with the value N (greater than 0), it will expand the bucket number of first level hash table by 2^N - 1, it hashs dirents into different buckets according their hash value, if we still move all dirents to first bucket, it makes incorrent locating for inline dirents, the result is, although we can iterate all dirents through ->readdir, we can't stat some of them in ->lookup which based on hash table searching. This patch fixes this issue by rehashing dirents into correct position when converting inline directory. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [bwh: Backported to 4.4: - Keep using f2fs_crypto functions instead of generic fscrypt API - Use remove_dirty_dir_inode() instead of remove_dirty_inode() - Adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

fscrypt: avoid collisions when presenting long encrypted filenames

2017-05-25T12:30:11Z

commit 6b06cdee81d68a8a829ad8e8d0f31d6836744af9 upstream. When accessing an encrypted directory without the key, userspace must operate on filenames derived from the ciphertext names, which contain arbitrary bytes. Since we must support filenames as long as NAME_MAX, we can't always just base64-encode the ciphertext, since that may make it too long. Currently, this is solved by presenting long names in an abbreviated form containing any needed filesystem-specific hashes (e.g. to identify a directory block), then the last 16 bytes of ciphertext. This needs to be sufficient to identify the actual name on lookup. However, there is a bug. It seems to have been assumed that due to the use of a CBC (ciphertext block chaining)-based encryption mode, the last 16 bytes (i.e. the AES block size) of ciphertext would depend on the full plaintext, preventing collisions. However, we actually use CBC with ciphertext stealing (CTS), which handles the last two blocks specially, causing them to appear "flipped". Thus, it's actually the second-to-last block which depends on the full plaintext. This caused long filenames that differ only near the end of their plaintexts to, when observed without the key, point to the wrong inode and be undeletable. For example, with ext4: # echo pass | e4crypt add_key -p 16 edir/ # 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 2004 # rm -rf edir/ rm: cannot remove 'edir/_A7nNFi3rhkEQlJ6P,hdzluhODKOeWx5V': Structure needs cleaning ... To fix this, when presenting long encrypted filenames, encode the second-to-last block of ciphertext rather than the last 16 bytes. Although it would be nice to solve this without depending on a specific encryption mode, that would mean doing a cryptographic hash like SHA-256 which would be much less efficient. This way is sufficient for now, and it's still compatible with encryption modes like HEH which are strong pseudorandom permutations. Also, changing the presented names is still allowed at any time because they are only provided to allow applications to do things like delete encrypted directories. They're not designed to be used to persistently identify files --- which would be hard to do anyway, given that they're encrypted after all. For ease of backports, this patch only makes the minimal fix to both ext4 and f2fs. It leaves ubifs as-is, since ubifs doesn't compare the ciphertext block yet. Follow-on patches will clean things up properly and make the filesystems use a shared helper function. Fixes: 5de0b4d0cd15 ("ext4 crypto: simplify and speed up filename encryption") Reported-by: Gwendal Grignou Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman

f2fs: check entire encrypted bigname when finding a dentry

2017-05-25T12:30:11Z

commit 6332cd32c8290a80e929fc044dc5bdba77396e33 upstream. 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 Signed-off-by: Greg Kroah-Hartman

f2fs: set GFP_NOFS for grab_cache_page

2015-10-12T20:38:03Z

For normal inodes, their pages are allocated with __GFP_FS, which can cause filesystem calls when reclaiming memory. This can incur a dead lock condition accordingly. So, this patch addresses this problem by introducing f2fs_grab_cache_page(.., bool for_write), which calls grab_cache_page_write_begin() with AOP_FLAG_NOFS. Signed-off-by: Jaegeuk Kim

f2fs crypto: allocate buffer for decrypting filename

2015-10-09T23:20:51Z

We got dentry pages from high_mem, and its address space directly goes into the decryption path via f2fs_fname_disk_to_usr. But, sg_init_one assumes the address is not from high_mem, so we can get this panic since it doesn't call kmap_high but kunmap_high is triggered at the end. kernel BUG at ../../../../../../kernel/mm/highmem.c:290! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM ... (kunmap_high+0xb0/0xb8) from [] (__kunmap_atomic+0xa0/0xa4) (__kunmap_atomic+0xa0/0xa4) from [] (blkcipher_walk_done+0x128/0x1ec) (blkcipher_walk_done+0x128/0x1ec) from [] (crypto_cbc_decrypt+0xc0/0x170) (crypto_cbc_decrypt+0xc0/0x170) from [] (crypto_cts_decrypt+0xc0/0x114) (crypto_cts_decrypt+0xc0/0x114) from [] (async_decrypt+0x40/0x48) (async_decrypt+0x40/0x48) from [] (f2fs_fname_disk_to_usr+0x124/0x304) (f2fs_fname_disk_to_usr+0x124/0x304) from [] (f2fs_fill_dentries+0xac/0x188) (f2fs_fill_dentries+0xac/0x188) from [] (f2fs_readdir+0x1f0/0x300) (f2fs_readdir+0x1f0/0x300) from [] (vfs_readdir+0x90/0xb4) (vfs_readdir+0x90/0xb4) from [] (SyS_getdents64+0x64/0xcc) (SyS_getdents64+0x64/0xcc) from [] (ret_fast_syscall+0x0/0x30) Cc: Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs: avoid clear valid page

2015-08-20T16:00:06Z

In f2fs_delete_entry, if last dirent is remove from the dentry page, we will try to punch that page since it has no valid date in it. But truncate_hole which is used for punching could fail because of no memory or IO error, if that happened, we'd better skip clearing this valid dentry page. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim

f2fs crypto: use per-inode tfm structure

2015-06-01T23:21:04Z

This patch applies the following ext4 patch: ext4 crypto: use per-inode tfm structure 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 Signed-off-by: Jaegeuk Kim