0098-Netfilter-Add-a-selection-for-Smack.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Casey Schaufler <casey@schaufler-ca.com>
Date: Fri, 31 Aug 2018 17:23:41 -0700
Subject: [PATCH] Netfilter: Add a selection for Smack

If you are running a single security module it's
fine to tell the netfilter system that your security
filters are for SELinux, and everything will work just
fine. If you have Smack and SELinux at the same time
you need to be able to differentiate. The netfilter
secmark (xt_SECMARK) code is set up for multiple security
modules, although as a comment points out, only one at
a time. The code wasn't set up to pass the information
about who should process the secmark in the case of
multiple security modules, so that had to be fixed.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/lsm_hooks.h                 |  4 +-
 include/linux/security.h                  | 20 ++++----
 include/uapi/linux/netfilter/xt_SECMARK.h |  1 +
 kernel/audit.c                            |  2 +
 kernel/auditsc.c                          |  2 +
 net/netfilter/nf_conntrack_netlink.c      | 10 ++++
 net/netfilter/nf_conntrack_standalone.c   |  5 ++
 net/netfilter/nfnetlink_queue.c           |  5 ++
 net/netfilter/xt_SECMARK.c                | 39 +++++++++++++---
 net/netlabel/netlabel_user.c              |  2 +-
 net/unix/af_unix.c                        |  8 +++-
 security/security.c                       | 37 +++++++++++----
 security/selinux/hooks.c                  | 13 +++++-
 security/smack/smack_lsm.c                | 56 +++++++++++++++++++----
 security/smack/smack_netfilter.c          | 11 +++++
 15 files changed, 175 insertions(+), 40 deletions(-)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 1b27b8bcc779..381dae9c3ec5 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1703,8 +1703,8 @@ union security_list_options {
 				const struct request_sock *req);
 	void (*inet_conn_established)(struct sock *sk, struct sk_buff *skb);
 	int (*secmark_relabel_packet)(struct secids *secid);
-	void (*secmark_refcount_inc)(void);
-	void (*secmark_refcount_dec)(void);
+	void (*secmark_refcount_inc)(u8 lsm);
+	void (*secmark_refcount_dec)(u8 lsm);
 	void (*req_classify_flow)(const struct request_sock *req,
 					struct flowi *fl);
 	int (*tun_dev_alloc_security)(void **security);
diff --git a/include/linux/security.h b/include/linux/security.h
index ad146916f19b..bb4b8ac9e1b2 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -83,15 +83,9 @@ enum lsm_event {
 
 struct secids {
 	u32 common;
-#ifdef CONFIG_SECURITY_SELINUX
 	u32 selinux;
-#endif
-#ifdef CONFIG_SECURITY_SMACK
 	u32 smack;
-#endif
-#ifdef CONFIG_SECURITY_APPARMOR
 	u32 apparmor;
-#endif
 	u32 flags;
 };
 
@@ -1315,8 +1309,9 @@ void security_inet_csk_clone(struct sock *newsk,
 void security_inet_conn_established(struct sock *sk,
 			struct sk_buff *skb);
 int security_secmark_relabel_packet(struct secids *secid);
-void security_secmark_refcount_inc(void);
-void security_secmark_refcount_dec(void);
+void security_secmark_refcount_inc(u8 lsm);
+void security_secmark_refcount_dec(u8 lsm);
+int security_secmark_mode(u8 lsm);
 int security_tun_dev_alloc_security(void **security);
 void security_tun_dev_free_security(void *security);
 int security_tun_dev_create(void);
@@ -1494,14 +1489,19 @@ static inline int security_secmark_relabel_packet(struct secids *secid)
 	return 0;
 }
 
-static inline void security_secmark_refcount_inc(void)
+static inline void security_secmark_refcount_inc(u8 lsm)
 {
 }
 
-static inline void security_secmark_refcount_dec(void)
+static inline void security_secmark_refcount_dec(u8 lsm)
 {
 }
 
+static inline int security_secmark_mode(u8 lsm)
+{
+	return 0;
+}
+
 static inline int security_tun_dev_alloc_security(void **security)
 {
 	return 0;
diff --git a/include/uapi/linux/netfilter/xt_SECMARK.h b/include/uapi/linux/netfilter/xt_SECMARK.h
index beb2cadba8a9..1f9f1b912d22 100644
--- a/include/uapi/linux/netfilter/xt_SECMARK.h
+++ b/include/uapi/linux/netfilter/xt_SECMARK.h
@@ -12,6 +12,7 @@
  * packets are being marked for.
  */
 #define SECMARK_MODE_SEL	0x01		/* SELinux */
+#define SECMARK_MODE_SMACK	0x02		/* Smack */
 #define SECMARK_SECCTX_MAX	256
 
 struct xt_secmark_target_info {
diff --git a/kernel/audit.c b/kernel/audit.c
index fdde19d100eb..4b227a99fc85 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2181,7 +2181,9 @@ void audit_log_name(struct audit_context *context, struct audit_names *n,
 		u32 len;
 		if (security_secid_to_secctx(
 			&n->osid, &ctx, &len)) {
+#ifndef CONFIG_SECURITY_STACKING
 			audit_log_format(ab, " osid=%u", n->osid.common);
+#endif
 			if (call_panic)
 				*call_panic = 2;
 		} else {
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8018f6cbd9be..498d8942c344 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1214,7 +1214,9 @@ static void show_special(struct audit_context *context, int *call_panic)
 			char *ctx = NULL;
 			u32 len;
 			if (security_secid_to_secctx(&osid, &ctx, &len)) {
+#ifndef CONFIG_SECURITY_STACKING
 				audit_log_format(ab, " osid=%u", osid.common);
+#endif
 				*call_panic = 1;
 			} else {
 				audit_log_format(ab, " obj=%s", ctx);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 157425412d1e..a3c80402f7a8 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -335,8 +335,13 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
 	char *secctx;
 	struct secids secid;
 
+#ifdef CONFIG_SECURITY_STACKING
 	secid_init(&secid);
+	secid.selinux = ct->secmark;
+	secid.smack = ct->secmark;
+#else
 	secid.common = ct->secmark;
+#endif
 
 	ret = security_secid_to_secctx(&secid, &secctx, &len);
 	if (ret)
@@ -629,8 +634,13 @@ static inline int ctnetlink_secctx_size(const struct nf_conn *ct)
 	int len, ret;
 	struct secids secid;
 
+#ifdef CONFIG_SECURITY_STACKING
 	secid_init(&secid);
+	secid.selinux = ct->secmark;
+	secid.smack = ct->secmark;
+#else
 	secid.common = ct->secmark;
+#endif
 
 	ret = security_secid_to_secctx(&secid, NULL, &len);
 	if (ret)
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index b9dd474c25de..24df21902d81 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -173,8 +173,13 @@ static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
 	char *secctx;
 	struct secids secid;
 
+#ifdef CONFIG_SECURITY_STACKING
 	secid_init(&secid);
+	secid.selinux = ct->secmark;
+	secid.smack = ct->secmark;
+#else
 	secid.common = ct->secmark;
+#endif
 
 	ret = security_secid_to_secctx(&secid, &secctx, &len);
 	if (ret)
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index e91fabdbe9e0..b5fe7f87f180 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -317,8 +317,13 @@ static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
 	read_lock_bh(&skb->sk->sk_callback_lock);
 
 	if (skb->secmark) {
+#ifdef CONFIG_SECURITY_STACKING
 		secid_init(&secid);
+		secid.selinux = skb->secmark;
+		secid.smack = skb->secmark;
+#else
 		secid.common = skb->secmark;
+#endif
 		security_secid_to_secctx(&secid, secdata, &seclen);
 	}
 
diff --git a/net/netfilter/xt_SECMARK.c b/net/netfilter/xt_SECMARK.c
index 08ad57b503b8..d46fd431e785 100644
--- a/net/netfilter/xt_SECMARK.c
+++ b/net/netfilter/xt_SECMARK.c
@@ -40,6 +40,9 @@ secmark_tg(struct sk_buff *skb, const struct xt_secmark_target_info_v1 *info)
 	case SECMARK_MODE_SEL:
 		secmark = info->secid;
 		break;
+	case SECMARK_MODE_SMACK:
+		secmark = info->secid;
+		break;
 	default:
 		BUG();
 	}
@@ -58,7 +61,16 @@ static int checkentry_lsm(struct xt_secmark_target_info_v1 *info)
 
 	err = security_secctx_to_secid(info->secctx, strlen(info->secctx),
 				       &secid);
-	info->secid = secid.selinux;
+	switch (info->mode) {
+	case SECMARK_MODE_SEL:
+		info->secid = secid.selinux;
+		break;
+	case SECMARK_MODE_SMACK:
+		info->secid = secid.smack;
+		break;
+	default:
+		BUG();
+	}
 
 	if (err) {
 		if (err == -EINVAL)
@@ -79,7 +91,8 @@ static int checkentry_lsm(struct xt_secmark_target_info_v1 *info)
 		return err;
 	}
 
-	security_secmark_refcount_inc();
+	if (mode)
+		security_secmark_refcount_inc(mode);
 	return 0;
 }
 
@@ -95,15 +108,23 @@ secmark_tg_check(const char *table, struct xt_secmark_target_info_v1 *info)
 		return -EINVAL;
 	}
 
-	if (mode && mode != info->mode) {
-		pr_info_ratelimited("mode already set to %hu cannot mix with rules for mode %hu\n",
-				    mode, info->mode);
+	if (mode) {
+		if (mode != info->mode) {
+			pr_info("mode already set to %hu cannot mix with "
+				"rules for mode %hu\n", mode, info->mode);
+			return -EINVAL;
+		}
+	} else if (security_secmark_mode(info->mode)) {
+		pr_info("mode already set and cannot mix with "
+			"rules for mode %hu\n", info->mode);
 		return -EINVAL;
 	}
 
 	switch (info->mode) {
 	case SECMARK_MODE_SEL:
 		break;
+	case SECMARK_MODE_SMACK:
+		break;
 	default:
 		pr_info_ratelimited("invalid mode: %hu\n", info->mode);
 		return -EINVAL;
@@ -122,8 +143,14 @@ static void secmark_tg_destroy(const struct xt_tgdtor_param *par)
 {
 	switch (mode) {
 	case SECMARK_MODE_SEL:
-		security_secmark_refcount_dec();
+		break;
+	case SECMARK_MODE_SMACK:
+		break;
+	default:
+		pr_info("invalid mode: %hu\n", mode);
+		return;
 	}
+	security_secmark_refcount_dec(mode);
 }
 
 static int secmark_tg_check_v0(const struct xt_tgchk_param *par)
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 22474f5c93d7..42ee220f6940 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -112,7 +112,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 			 from_kuid(&init_user_ns, audit_info->loginuid),
 			 audit_info->sessionid);
 
-	if (audit_info->secid.common != 0 &&
+	if (secid_valid(&audit_info->secid) &&
 	    security_secid_to_secctx(&audit_info->secid,
 				     &secctx,
 				     &secctx_len) == 0) {
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 991d3540f50d..a7b3dc16cde6 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -141,9 +141,10 @@ static struct hlist_head *unix_sockets_unbound(void *addr)
 #ifdef CONFIG_SECURITY_NETWORK
 static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
 {
-	UNIXCB(skb).secid = scm->secid.common;
 #ifdef CONFIG_SECURITY_STACKING
 	secid_to_skb(&scm->secid, skb);
+#else
+	UNIXCB(skb).secid = scm->secid.common;
 #endif
 }
 
@@ -158,7 +159,12 @@ static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
 
 static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
 {
+#ifdef CONFIG_SECURITY_STACKING
+	return memcmp(&scm->secid, &(UNIXCB(skb).secid),
+		      sizeof(scm->secid)) == 0;
+#else
 	return (scm->secid.common == UNIXCB(skb).secid);
+#endif
 }
 #else
 static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
diff --git a/security/security.c b/security/security.c
index 96e795600adb..5a8047fcb9cd 100644
--- a/security/security.c
+++ b/security/security.c
@@ -351,10 +351,9 @@ void __init security_add_blobs(struct lsm_blob_sizes *needed)
 	lsm_set_size(&needed->lbs_key, &blob_sizes.lbs_key);
 #endif
 	lsm_set_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
-#ifdef CONFIG_NETWORK_SECMARK
+#ifdef CONFIG_SECURITY_NETWORK
 	/*
-	 * Store the most likely secmark with the socket
-	 * so that it doesn't have to be a managed object.
+	 * Store the secids with the socket for UDS.
 	 */
 	if (needed->lbs_sock && blob_sizes.lbs_sock == 0)
 		blob_sizes.lbs_sock = sizeof(struct secids);
@@ -2238,11 +2237,17 @@ int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
 #ifdef CONFIG_SECURITY_STACKING
 	struct security_hook_list *hp;
 	int rc = -ENOPROTOOPT;
+	int trc;
 
 	secid_init(secid);
 	hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_dgram,
-				list)
-		rc = hp->hook.socket_getpeersec_dgram(sock, skb, secid);
+				list) {
+		trc = hp->hook.socket_getpeersec_dgram(sock, skb, secid);
+		if (trc == 0)
+			rc = 0;
+		else if (trc != -ENOPROTOOPT)
+			return trc;
+	}
 
 	return rc;
 #else
@@ -2332,18 +2337,32 @@ int security_secmark_relabel_packet(struct secids *secid)
 }
 EXPORT_SYMBOL(security_secmark_relabel_packet);
 
-void security_secmark_refcount_inc(void)
+void security_secmark_refcount_inc(u8 lsm)
 {
-	call_void_hook(secmark_refcount_inc);
+	call_void_hook(secmark_refcount_inc, lsm);
 }
 EXPORT_SYMBOL(security_secmark_refcount_inc);
 
-void security_secmark_refcount_dec(void)
+void security_secmark_refcount_dec(u8 lsm)
 {
-	call_void_hook(secmark_refcount_dec);
+	call_void_hook(secmark_refcount_dec, lsm);
 }
 EXPORT_SYMBOL(security_secmark_refcount_dec);
 
+static u8 security_secmark_mode_value;
+
+int security_secmark_mode(u8 lsm)
+{
+	if (security_secmark_mode_value == 0) {
+		security_secmark_mode_value = lsm;
+		return 0;
+	}
+	if (security_secmark_mode_value == lsm)
+		return 0;
+	return -EBUSY;
+}
+EXPORT_SYMBOL(security_secmark_mode);
+
 int security_tun_dev_alloc_security(void **security)
 {
 	return call_int_hook(tun_dev_alloc_security, 0, security);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 666f2b631614..02a9aab5e901 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -50,6 +50,7 @@
 #include <linux/mount.h>
 #include <linux/netfilter_ipv4.h>
 #include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/xt_SECMARK.h>
 #include <linux/tty.h>
 #include <net/icmp.h>
 #include <net/ip.h>		/* for local_port_range[] */
@@ -5407,13 +5408,21 @@ static int selinux_secmark_relabel_packet(struct secids *secid)
 			    PACKET__RELABELTO, NULL);
 }
 
-static void selinux_secmark_refcount_inc(void)
+static void selinux_secmark_refcount_inc(u8 lsm)
 {
+#ifdef CONFIG_SECURITY_STACKING
+	if (lsm != SECMARK_MODE_SEL)
+		return;
+#endif
 	atomic_inc(&selinux_secmark_refcount);
 }
 
-static void selinux_secmark_refcount_dec(void)
+static void selinux_secmark_refcount_dec(u8 lsm)
 {
+#ifdef CONFIG_SECURITY_STACKING
+	if (lsm != SECMARK_MODE_SEL)
+		return;
+#endif
 	atomic_dec(&selinux_secmark_refcount);
 }
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index dd0313001e5e..bf2e6537dce7 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -35,6 +35,7 @@
 #include <net/cipso_ipv4.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
+#include <linux/netfilter/xt_SECMARK.h>
 #include <linux/audit.h>
 #include <linux/magic.h>
 #include <linux/dcache.h>
@@ -52,6 +53,11 @@
 #define SMK_RECEIVING	1
 #define SMK_SENDING	2
 
+/*
+ * SECMARK reference count
+ */
+static atomic_t smack_secmark_refcount = ATOMIC_INIT(0);
+
 #ifdef SMACK_IPV6_PORT_LABELING
 DEFINE_MUTEX(smack_ipv6_lock);
 static LIST_HEAD(smk_ipv6_port_list);
@@ -3815,6 +3821,19 @@ static int smk_skb_to_addr_ipv6(struct sk_buff *skb, struct sockaddr_in6 *sip)
 }
 #endif /* CONFIG_IPV6 */
 
+#ifdef CONFIG_SECURITY_SMACK_NETFILTER
+static bool smack_owns_secmark(const struct sk_buff *skb)
+{
+	if (skb == NULL || skb->secmark == 0)
+		return false;
+#ifdef CONFIG_SECURITY_STACKING
+	return atomic_read(&smack_secmark_refcount) != 0;
+#else
+	return true;
+#endif
+}
+#endif /* CONFIG_SECURITY_SMACK_NETFILTER */
+
 /**
  * smack_socket_sock_rcv_skb - Smack packet delivery access check
  * @sk: socket
@@ -3849,7 +3868,7 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		 * If there is no secmark fall back to CIPSO.
 		 * The secmark is assumed to reflect policy better.
 		 */
-		if (skb && skb->secmark != 0) {
+		if (smack_owns_secmark(skb)) {
 			skp = smack_from_secid(skb->secmark);
 			goto access_check;
 		}
@@ -3895,7 +3914,7 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		    proto != IPPROTO_TCP && proto != IPPROTO_DCCP)
 			break;
 #ifdef SMACK_IPV6_SECMARK_LABELING
-		if (skb)
+		if (smack_owns_secmark(skb))
 			skp = smack_from_secid(skb->secmark);
 		else
 			skp = smack_ipv6host_label(&sadd);
@@ -3997,7 +4016,7 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
 		break;
 	case PF_INET:
 #ifdef CONFIG_SECURITY_SMACK_NETFILTER
-		if (skb->secmark) {
+		if (smack_owns_secmark(skb)) {
 			s = skb->secmark;
 			if (s != 0)
 				break;
@@ -4018,7 +4037,8 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
 		break;
 	case PF_INET6:
 #ifdef SMACK_IPV6_SECMARK_LABELING
-		s = skb->secmark;
+		if (smack_owns_secmark(skb))
+			s = skb->secmark;
 #endif
 		break;
 	}
@@ -4096,11 +4116,9 @@ static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	 * If there is no secmark fall back to CIPSO.
 	 * The secmark is assumed to reflect policy better.
 	 */
-	if (skb) {
-		if (skb->secmark != 0) {
-			skp = smack_from_secid(skb->secmark);
-			goto access_check;
-		}
+	if (smack_owns_secmark(skb)) {
+		skp = smack_from_secid(skb->secmark);
+		goto access_check;
 	}
 #endif /* CONFIG_SECURITY_SMACK_NETFILTER */
 
@@ -4176,6 +4194,24 @@ static void smack_inet_csk_clone(struct sock *sk,
 		ssp->smk_packet = NULL;
 }
 
+static void smack_secmark_refcount_inc(u8 lsm)
+{
+#ifdef CONFIG_SECURITY_STACKING
+	if (lsm != SECMARK_MODE_SMACK)
+		return;
+#endif
+	atomic_inc(&smack_secmark_refcount);
+}
+
+static void smack_secmark_refcount_dec(u8 lsm)
+{
+#ifdef CONFIG_SECURITY_STACKING
+	if (lsm != SECMARK_MODE_SMACK)
+		return;
+#endif
+	atomic_dec(&smack_secmark_refcount);
+}
+
 /*
  * Key management security hooks
  *
@@ -4690,6 +4726,8 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sock_graft, smack_sock_graft),
 	LSM_HOOK_INIT(inet_conn_request, smack_inet_conn_request),
 	LSM_HOOK_INIT(inet_csk_clone, smack_inet_csk_clone),
+	LSM_HOOK_INIT(secmark_refcount_inc, smack_secmark_refcount_inc),
+	LSM_HOOK_INIT(secmark_refcount_dec, smack_secmark_refcount_dec),
 
  /* key management security hooks */
 #ifdef CONFIG_KEYS
diff --git a/security/smack/smack_netfilter.c b/security/smack/smack_netfilter.c
index 701a1cc1bdcc..596aba2e4d6b 100644
--- a/security/smack/smack_netfilter.c
+++ b/security/smack/smack_netfilter.c
@@ -16,6 +16,7 @@
 
 #include <linux/netfilter_ipv4.h>
 #include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/xt_SECMARK.h>
 #include <linux/netdevice.h>
 #include <net/inet_sock.h>
 #include <net/net_namespace.h>
@@ -31,6 +32,11 @@ static unsigned int smack_ipv6_output(void *priv,
 	struct socket_smack *ssp;
 	struct smack_known *skp;
 
+#ifdef CONFIG_SECURITY_STACKING
+	if (security_secmark_mode(SECMARK_MODE_SMACK))
+		return NF_ACCEPT;
+#endif
+
 	if (sk && smack_sock(sk)) {
 		ssp = smack_sock(sk);
 		skp = ssp->smk_out;
@@ -49,6 +55,11 @@ static unsigned int smack_ipv4_output(void *priv,
 	struct socket_smack *ssp;
 	struct smack_known *skp;
 
+#ifdef CONFIG_SECURITY_STACKING
+	if (security_secmark_mode(SECMARK_MODE_SMACK))
+		return NF_ACCEPT;
+#endif
+
 	if (sk && smack_sock(sk)) {
 		ssp = smack_sock(sk);
 		skp = ssp->smk_out;
-- 
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