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linux/fs/ecryptfs
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Tyler Hicks e86281e700 eCryptfs: don't pass up plaintext names when using filename encryption 
Both ecryptfs_filldir() and ecryptfs_readlink_lower() use
ecryptfs_decode_and_decrypt_filename() to translate lower filenames to
upper filenames. The function correctly passes up lower filenames,
unchanged, when filename encryption isn't in use. However, it was also
passing up lower filenames when the filename wasn't encrypted or
when decryption failed. Since 88ae4ab980, eCryptfs refuses to lookup
lower plaintext names when filename encryption is enabled so this
resulted in a situation where userspace would see lower plaintext
filenames in calls to getdents(2) but then not be able to lookup those
filenames.

An example of this can be seen when enabling filename encryption on an
eCryptfs mount at the root directory of an Ext4 filesystem:

$ ls -1i /lower
12 ECRYPTFS_FNEK_ENCRYPTED.FWYZD8TcW.5FV-TKTEYOHsheiHX9a-w.NURCCYIMjI8pn5BDB9-h3fXwrE--
11 lost+found
$ ls -1i /upper
ls: cannot access '/upper/lost+found': No such file or directory
 ? lost+found
12 test

With this change, the lower lost+found dentry is ignored:

$ ls -1i /lower
12 ECRYPTFS_FNEK_ENCRYPTED.FWYZD8TcW.5FV-TKTEYOHsheiHX9a-w.NURCCYIMjI8pn5BDB9-h3fXwrE--
11 lost+found
$ ls -1i /upper
12 test

Additionally, some potentially noisy error/info messages in the related
code paths are turned into debug messages so that the logs can't be
easily filled.

Fixes: 88ae4ab980 ("ecryptfs_lookup(): try either only encrypted or plaintext name")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
2018-04-16 18:51:22 +00:00
..
crypto.c eCryptfs: don't pass up plaintext names when using filename encryption 2018-04-16 18:51:22 +00:00
debug.c
dentry.c eCryptfs: Invalidate dcache entries when lower i_nlink is zero 2015-08-18 17:29:48 -05:00
ecryptfs_kernel.h ecryptfs: remove private bin2hex implementation 2017-11-04 22:16:41 +00:00
file.c eCryptfs: don't pass up plaintext names when using filename encryption 2018-04-16 18:51:22 +00:00
inode.c ecryptfs: lookup: Don't check if mount_crypt_stat is NULL 2018-03-29 01:33:29 +00:00
Kconfig
keystore.c ecryptfs: fix spelling mistake: "cadidate" -> "candidate" 2018-03-29 01:33:30 +00:00
kthread.c scripts/spelling.txt: add "againt" pattern and fix typo instances 2017-02-27 18:43:47 -08:00
main.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
Makefile
messaging.c ecryptfs: Delete 21 error messages for a failed memory allocation 2017-11-06 18:23:29 +00:00
miscdev.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
mmap.c ecryptfs: Delete 21 error messages for a failed memory allocation 2017-11-06 18:23:29 +00:00
read_write.c fs: fix kernel_write prototype 2017-09-04 19:05:15 -04:00
super.c eCryptfs: Do not allocate hash tfm in NORECLAIM context 2016-04-20 17:50:01 +08:00