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authorDavid Howells <dhowells@redhat.com>2018-05-16 21:25:46 +0100
committerDavid Howells <dhowells@redhat.com>2018-05-16 21:35:23 +0100
commit378831e4daec75fbba6d3612bcf3b4dd00ddbf08 (patch)
tree66cdf5ae7efa2fe90491caa6cd15c6158791f17e /fs/afs/security.c
parent21b9f1c7e319f654de3b2574fe8d4e4114c9143f (diff)
downloadlinux-378831e4daec75fbba6d3612bcf3b4dd00ddbf08.tar.bz2
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/afs/security.c')
-rw-r--r--fs/afs/security.c10
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))