Audit: use new LSM hooks instead of SELinux exports

Stop using the following exported SELinux interfaces:
selinux_get_inode_sid(inode, sid)
selinux_get_ipc_sid(ipcp, sid)
selinux_get_task_sid(tsk, sid)
selinux_sid_to_string(sid, ctx, len)
kfree(ctx)

and use following generic LSM equivalents respectively:
security_inode_getsecid(inode, secid)
security_ipc_getsecid*(ipcp, secid)
security_task_getsecid(tsk, secid)
security_sid_to_secctx(sid, ctx, len)
security_release_secctx(ctx, len)

Call security_release_secctx only if security_secid_to_secctx
succeeded.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: James Morris <jmorris@namei.org>
Reviewed-by: Paul Moore <paul.moore@hp.com>
diff --git a/kernel/audit.c b/kernel/audit.c
index b782b04..784a48e9 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -265,13 +265,13 @@
 		char *ctx = NULL;
 		u32 len;
 
-		rc = selinux_sid_to_string(sid, &ctx, &len);
+		rc = security_secid_to_secctx(sid, &ctx, &len);
 		if (rc) {
 			audit_log_format(ab, " sid=%u", sid);
 			allow_changes = 0; /* Something weird, deny request */
 		} else {
 			audit_log_format(ab, " subj=%s", ctx);
-			kfree(ctx);
+			security_release_secctx(ctx, len);
 		}
 	}
 	audit_log_format(ab, " res=%d", allow_changes);
@@ -550,12 +550,13 @@
 	audit_log_format(*ab, "user pid=%d uid=%u auid=%u",
 			 pid, uid, auid);
 	if (sid) {
-		rc = selinux_sid_to_string(sid, &ctx, &len);
+		rc = security_secid_to_secctx(sid, &ctx, &len);
 		if (rc)
 			audit_log_format(*ab, " ssid=%u", sid);
-		else
+		else {
 			audit_log_format(*ab, " subj=%s", ctx);
-		kfree(ctx);
+			security_release_secctx(ctx, len);
+		}
 	}
 
 	return rc;
@@ -758,18 +759,18 @@
 		break;
 	}
 	case AUDIT_SIGNAL_INFO:
-		err = selinux_sid_to_string(audit_sig_sid, &ctx, &len);
+		err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
 		if (err)
 			return err;
 		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 		if (!sig_data) {
-			kfree(ctx);
+			security_release_secctx(ctx, len);
 			return -ENOMEM;
 		}
 		sig_data->uid = audit_sig_uid;
 		sig_data->pid = audit_sig_pid;
 		memcpy(sig_data->ctx, ctx, len);
-		kfree(ctx);
+		security_release_secctx(ctx, len);
 		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 				0, 0, sig_data, sizeof(*sig_data) + len);
 		kfree(sig_data);