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| author | David Howells <dhowells@redhat.com> | 2018-05-16 22:25:46 +0200 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2018-05-16 22:35:23 +0200 |
| commit | 378831e4daec75fbba6d3612bcf3b4dd00ddbf08 (patch) | |
| tree | 66cdf5ae7efa2fe90491caa6cd15c6158791f17e /fs | |
| parent | Merge tag 'afs-fixes-20180514' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff) | |
| download | linux-378831e4daec75fbba6d3612bcf3b4dd00ddbf08.tar.xz linux-378831e4daec75fbba6d3612bcf3b4dd00ddbf08.zip | |
afs: Fix directory permissions check
Doing faccessat("/afs/some/directory", 0) triggers a BUG in the permissions
check code.
Fix this by just removing the BUG section. If no permissions are asked
for, just return okay if the file exists.
Also:
(1) Split up the directory check so that it has separate if-statements
rather than if-else-if (e.g. checking for MAY_EXEC shouldn't skip the
check for MAY_READ and MAY_WRITE).
(2) Check for MAY_CHDIR as MAY_EXEC.
Without the main fix, the following BUG may occur:
kernel BUG at fs/afs/security.c:386!
invalid opcode: 0000 [#1] SMP PTI
...
RIP: 0010:afs_permission+0x19d/0x1a0 [kafs]
...
Call Trace:
? inode_permission+0xbe/0x180
? do_faccessat+0xdc/0x270
? do_syscall_64+0x60/0x1f0
? entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: 00d3b7a4533e ("[AFS]: Add security support.")
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/afs/security.c | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/fs/afs/security.c b/fs/afs/security.c index 1992b0ffa543..81dfedb7879f 100644 --- a/fs/afs/security.c +++ b/fs/afs/security.c @@ -372,18 +372,14 @@ int afs_permission(struct inode *inode, int mask) mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file"); if (S_ISDIR(inode->i_mode)) { - if (mask & MAY_EXEC) { + if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) { if (!(access & AFS_ACE_LOOKUP)) goto permission_denied; - } else if (mask & MAY_READ) { - if (!(access & AFS_ACE_LOOKUP)) - goto permission_denied; - } else if (mask & MAY_WRITE) { + } + if (mask & MAY_WRITE) { if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */ AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */ goto permission_denied; - } else { - BUG(); } } else { if (!(access & AFS_ACE_LOOKUP)) |