selinux: change the handling of unknown classes

If allow_unknown==deny, SELinux treats an undefined kernel security
class as an error condition rather than as a typical permission denial
and thus does not allow permissions on undefined classes even when in
permissive mode.  Change the SELinux logic so that this case is handled
as a typical permission denial, subject to the usual permissive mode and
permissive domain handling.

Also drop the 'requested' argument from security_compute_av() and
helpers as it is a legacy of the original security server interface and
is unused.

Changes:
- Handle permissive domains consistently by moving up the test for a
permissive domain.
- Make security_compute_av_user() consistent with security_compute_av();
the only difference now is that security_compute_av() performs mapping
between the kernel-private class and permission indices and the policy
values.  In the userspace case, this mapping is handled by libselinux.
- Moved avd_init inside the policy lock.

Based in part on a patch by Paul Moore <paul.moore@hp.com>.

Reported-by: Andrew Worsley <amworsley@gmail.com>
Signed-off-by:  Stephen D. Smalley <sds@tycho.nsa.gov>
Reviewed-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 1 insertions, 4 deletions

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index f2dde26..3ee9b6a 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -746,9 +746,7 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 		else
 			avd = &avd_entry;
 
-		rc = security_compute_av(ssid, tsid, tclass, requested, avd);
-		if (rc)
-			goto out;
+		security_compute_av(ssid, tsid, tclass, avd);
 		rcu_read_lock();
 		node = avc_insert(ssid, tsid, tclass, avd);
 	} else {
@@ -770,7 +768,6 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 	}
 
 	rcu_read_unlock();
-out:
 	return rc;
 }