xfs: don't generate selinux audit messages for capability testing

There are a few places where we test the current process' capability set
to decide if we're going to be more or less generous with resource
acquisition for a system call.  If the process doesn't have the
capability, we can continue the call, albeit in a degraded mode.

These are /not/ the actual security decisions, so it's not proper to use
capable(), which (in certain selinux setups) causes audit messages to
get logged.  Switch them to has_capability_noaudit.

Fixes: 7317a03 ("xfs: refactor inode ownership change transaction/inode/quota allocation idiom")
Fixes: ea9a46e ("xfs: only return detailed fsmap info if the caller has CAP_SYS_ADMIN")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>

fs/xfs/xfs_fsmap.c

@@ -864,8 +864,8 @@ xfs_getfsmap(
 	    !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1]))
 		return -EINVAL;
 
-	use_rmap = capable(CAP_SYS_ADMIN) &&
-		   xfs_has_rmapbt(mp);
+	use_rmap = xfs_has_rmapbt(mp) &&
+		   has_capability_noaudit(current, CAP_SYS_ADMIN);
 	head->fmh_entries = 0;
 
 	/* Set up our device handlers. */

fs/xfs/xfs_ioctl.c

@@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans(
 		goto out_error;
 
 	error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp,
-			capable(CAP_FOWNER), &tp);
+			has_capability_noaudit(current, CAP_FOWNER), &tp);
 	if (error)
 		goto out_error;
 

fs/xfs/xfs_iops.c

@@ -723,7 +723,7 @@ xfs_setattr_nonsize(
 	}
 
 	error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL,
-			capable(CAP_FOWNER), &tp);
+			has_capability_noaudit(current, CAP_FOWNER), &tp);
 	if (error)
 		goto out_dqrele;
 

kernel/capability.c

@@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap)
 {
 	return has_ns_capability_noaudit(t, &init_user_ns, cap);
 }
+EXPORT_SYMBOL(has_capability_noaudit);
 
 static bool ns_capable_common(struct user_namespace *ns,
 			      int cap,