selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link
commit bda0be7ad9948 ("security: make inode_follow_link RCU-walk aware")
switched selinux_inode_follow_link() to use avc_has_perm_flags() and
pass down the MAY_NOT_BLOCK flag if called during RCU walk. However,
the only test of MAY_NOT_BLOCK occurs during slow_avc_audit()
and only if passing an inode as audit data (LSM_AUDIT_DATA_INODE). Since
selinux_inode_follow_link() passes a dentry directly, passing MAY_NOT_BLOCK
here serves no purpose. Switch selinux_inode_follow_link() to use
avc_has_perm() and drop avc_has_perm_flags() since there are no other
users.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 5de18a6..9b63d8e 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -867,9 +867,8 @@
* permissive mode that only appear when in enforcing mode.
*
* See the corresponding handling in slow_avc_audit(), and the
- * logic in selinux_inode_follow_link and selinux_inode_permission
- * for the VFS MAY_NOT_BLOCK flag, which is transliterated into
- * AVC_NONBLOCKING for avc_has_perm_noaudit().
+ * logic in selinux_inode_permission for the MAY_NOT_BLOCK flag,
+ * which is transliterated into AVC_NONBLOCKING.
*/
if (flags & AVC_NONBLOCKING)
return 0;
@@ -1209,25 +1208,6 @@
return rc;
}
-int avc_has_perm_flags(struct selinux_state *state,
- u32 ssid, u32 tsid, u16 tclass, u32 requested,
- struct common_audit_data *auditdata,
- int flags)
-{
- struct av_decision avd;
- int rc, rc2;
-
- rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested,
- (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
- &avd);
-
- rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
- auditdata, flags);
- if (rc2)
- return rc2;
- return rc;
-}
-
u32 avc_policy_seqno(struct selinux_state *state)
{
return state->avc->avc_cache.latest_notif;