diff mbox series

[v35,21/29] LSM: Extend security_secid_to_secctx to include module selection

Message ID 20220418145945.38797-22-casey@schaufler-ca.com (mailing list archive)
State New
Headers show
Series [v35,01/29] integrity: disassociate ima_filter_rule from security_audit_rule | expand

Commit Message

Casey Schaufler April 18, 2022, 2:59 p.m. UTC
Add a parameter to security_secid_to_secctx() to identify
which of the security modules that may be active should
provide the security context. If the parameter is greater
than or equal to zero, the security module associated with
that LSM "slot" is used. If the value is LSMBLOB_DISPLAY
the "interface lsm" is used. If the value is LSMBLOB_FIRST
the first security module providing a hook is used.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 drivers/android/binder.c                |  2 +-
 include/linux/security.h                |  7 +++++--
 include/net/scm.h                       |  2 +-
 kernel/audit.c                          |  4 ++--
 kernel/auditsc.c                        |  7 ++++---
 net/ipv4/ip_sockglue.c                  |  2 +-
 net/netfilter/nf_conntrack_netlink.c    |  4 ++--
 net/netfilter/nf_conntrack_standalone.c |  2 +-
 net/netfilter/nfnetlink_queue.c         |  2 +-
 net/netlabel/netlabel_unlabeled.c       | 11 +++++++----
 net/netlabel/netlabel_user.c            |  2 +-
 security/security.c                     | 20 ++++++++++++++++++--
 12 files changed, 44 insertions(+), 21 deletions(-)

Comments

John Johansen April 25, 2022, 11:32 p.m. UTC | #1
On 4/18/22 07:59, Casey Schaufler wrote:
> Add a parameter to security_secid_to_secctx() to identify
> which of the security modules that may be active should
> provide the security context. If the parameter is greater
> than or equal to zero, the security module associated with
> that LSM "slot" is used. If the value is LSMBLOB_DISPLAY
> the "interface lsm" is used. If the value is LSMBLOB_FIRST
> the first security module providing a hook is used.
> 

So the patch does change behavior from previously doing
effectively LSMBLOB_DISPLAY everywhere to using LSMBLOB_FIRST
in certain cases. I think the reason for the change needs
to called out. I think a note in the patch description
would do.


> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>  drivers/android/binder.c                |  2 +-
>  include/linux/security.h                |  7 +++++--
>  include/net/scm.h                       |  2 +-
>  kernel/audit.c                          |  4 ++--
>  kernel/auditsc.c                        |  7 ++++---
>  net/ipv4/ip_sockglue.c                  |  2 +-
>  net/netfilter/nf_conntrack_netlink.c    |  4 ++--
>  net/netfilter/nf_conntrack_standalone.c |  2 +-
>  net/netfilter/nfnetlink_queue.c         |  2 +-
>  net/netlabel/netlabel_unlabeled.c       | 11 +++++++----
>  net/netlabel/netlabel_user.c            |  2 +-
>  security/security.c                     | 20 ++++++++++++++++++--
>  12 files changed, 44 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 259f5e38e6ba..d59c4ebf7e22 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -2983,7 +2983,7 @@ static void binder_transaction(struct binder_proc *proc,
>  		size_t added_size;
>  
>  		security_cred_getsecid(proc->cred, &blob);
> -		ret = security_secid_to_secctx(&blob, &lsmctx);
> +		ret = security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_DISPLAY);
>  		if (ret) {
>  			return_error = BR_FAILED_REPLY;
>  			return_error_param = ret;
> diff --git a/include/linux/security.h b/include/linux/security.h
> index dc66f3f48456..2150016492be 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -184,6 +184,8 @@ struct lsmblob {
>  #define LSMBLOB_INVALID		-1	/* Not a valid LSM slot number */
>  #define LSMBLOB_NEEDED		-2	/* Slot requested on initialization */
>  #define LSMBLOB_NOT_NEEDED	-3	/* Slot not requested */
> +#define LSMBLOB_DISPLAY		-4	/* Use the "interface_lsm" slot */
> +#define LSMBLOB_FIRST		-5	/* Use the first slot */
>  
>  /**
>   * lsmblob_init - initialize a lsmblob structure
> @@ -615,7 +617,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
>  			 size_t size);
>  int security_netlink_send(struct sock *sk, struct sk_buff *skb);
>  int security_ismaclabel(const char *name);
> -int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
> +int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
> +			     int ilsm);
>  int security_secctx_to_secid(const char *secdata, u32 seclen,
>  			     struct lsmblob *blob);
>  void security_release_secctx(struct lsmcontext *cp);
> @@ -1470,7 +1473,7 @@ static inline int security_ismaclabel(const char *name)
>  }
>  
>  static inline int security_secid_to_secctx(struct lsmblob *blob,
> -					   struct lsmcontext *cp)
> +					   struct lsmcontext *cp, int ilsm)
>  {
>  	return -EOPNOTSUPP;
>  }
> diff --git a/include/net/scm.h b/include/net/scm.h
> index b77a52f93389..f4d567d4885e 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -101,7 +101,7 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
>  		 * and the infrastructure will know which it is.
>  		 */
>  		lsmblob_init(&lb, scm->secid);
> -		err = security_secid_to_secctx(&lb, &context);
> +		err = security_secid_to_secctx(&lb, &context, LSMBLOB_DISPLAY);
>  
>  		if (!err) {
>  			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, context.len,
> diff --git a/kernel/audit.c b/kernel/audit.c
> index a885ebdbb91e..28ff7a5f90bd 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1464,7 +1464,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>  
>  		if (lsmblob_is_set(&audit_sig_lsm)) {
>  			err = security_secid_to_secctx(&audit_sig_lsm,
> -						       &context);
> +						       &context, LSMBLOB_FIRST);
>  			if (err)
>  				return err;
>  		}
> @@ -2176,7 +2176,7 @@ int audit_log_task_context(struct audit_buffer *ab)
>  	if (!lsmblob_is_set(&blob))
>  		return 0;
>  
> -	error = security_secid_to_secctx(&blob, &context);
> +	error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST);
>  
>  	if (error) {
>  		if (error != -EINVAL)
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 802de65259d8..231631f61550 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1132,7 +1132,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
>  			 from_kuid(&init_user_ns, auid),
>  			 from_kuid(&init_user_ns, uid), sessionid);
>  	if (lsmblob_is_set(blob)) {
> -		if (security_secid_to_secctx(blob, &lsmctx)) {
> +		if (security_secid_to_secctx(blob, &lsmctx, LSMBLOB_FIRST)) {
>  			audit_log_format(ab, " obj=(none)");
>  			rc = 1;
>  		} else {
> @@ -1425,7 +1425,8 @@ static void show_special(struct audit_context *context, int *call_panic)
>  			struct lsmblob blob;
>  
>  			lsmblob_init(&blob, osid);
> -			if (security_secid_to_secctx(&blob, &lsmcxt)) {
> +			if (security_secid_to_secctx(&blob, &lsmcxt,
> +						     LSMBLOB_FIRST)) {
>  				audit_log_format(ab, " osid=%u", osid);
>  				*call_panic = 1;
>  			} else {
> @@ -1593,7 +1594,7 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
>  		struct lsmcontext lsmctx;
>  
>  		lsmblob_init(&blob, n->osid);
> -		if (security_secid_to_secctx(&blob, &lsmctx)) {
> +		if (security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_FIRST)) {
>  			audit_log_format(ab, " osid=%u", n->osid);
>  			if (call_panic)
>  				*call_panic = 2;
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index ad5be7707bca..9b5c44dec1e9 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -140,7 +140,7 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
>  		return;
>  
>  	lsmblob_init(&lb, secid);
> -	err = security_secid_to_secctx(&lb, &context);
> +	err = security_secid_to_secctx(&lb, &context, LSMBLOB_DISPLAY);
>  	if (err)
>  		return;
>  
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index 07660c7dd342..5d72d2f41562 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -353,7 +353,7 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
>  	 * security_secid_to_secctx() will know which security module
>  	 * to use to create the secctx.  */
>  	lsmblob_init(&blob, ct->secmark);
> -	ret = security_secid_to_secctx(&blob, &context);
> +	ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
>  	if (ret)
>  		return 0;
>  
> @@ -663,7 +663,7 @@ static inline int ctnetlink_secctx_size(const struct nf_conn *ct)
>  	int len;
>  	struct lsmblob blob;
>  
> -	len = security_secid_to_secctx(&blob, NULL);
> +	len = security_secid_to_secctx(&blob, NULL, LSMBLOB_DISPLAY);
>  	if (len <= 0)
>  		return 0;
>  
> diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
> index 36338660df3c..cb4b8b636f6a 100644
> --- a/net/netfilter/nf_conntrack_standalone.c
> +++ b/net/netfilter/nf_conntrack_standalone.c
> @@ -180,7 +180,7 @@ static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
>  	struct lsmcontext context;
>  
>  	lsmblob_init(&blob, ct->secmark);
> -	ret = security_secid_to_secctx(&blob, &context);
> +	ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
>  	if (ret)
>  		return;
>  
> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index f60a0b6240ff..844955b2e163 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -316,7 +316,7 @@ static void nfqnl_get_sk_secctx(struct sk_buff *skb, struct lsmcontext *context)
>  		 * blob. security_secid_to_secctx() will know which security
>  		 * module to use to create the secctx.  */
>  		lsmblob_init(&blob, skb->secmark);
> -		security_secid_to_secctx(&blob, context);
> +		security_secid_to_secctx(&blob, context, LSMBLOB_DISPLAY);
>  	}
>  
>  	read_unlock_bh(&skb->sk->sk_callback_lock);
> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
> index 910a03f15b0d..8deee7e176a9 100644
> --- a/net/netlabel/netlabel_unlabeled.c
> +++ b/net/netlabel/netlabel_unlabeled.c
> @@ -437,7 +437,8 @@ int netlbl_unlhsh_add(struct net *net,
>  unlhsh_add_return:
>  	rcu_read_unlock();
>  	if (audit_buf != NULL) {
> -		if (security_secid_to_secctx(lsmblob, &context) == 0) {
> +		if (security_secid_to_secctx(lsmblob, &context,
> +					     LSMBLOB_FIRST) == 0) {
>  			audit_log_format(audit_buf, " sec_obj=%s",
>  					 context.context);
>  			security_release_secctx(&context);
> @@ -491,7 +492,8 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
>  					  addr->s_addr, mask->s_addr);
>  		dev_put(dev);
>  		if (entry != NULL &&
> -		    security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
> +		    security_secid_to_secctx(&entry->lsmblob, &context,
> +					     LSMBLOB_FIRST) == 0) {
>  			audit_log_format(audit_buf, " sec_obj=%s",
>  					 context.context);
>  			security_release_secctx(&context);
> @@ -550,7 +552,8 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
>  					  addr, mask);
>  		dev_put(dev);
>  		if (entry != NULL &&
> -		    security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
> +		    security_secid_to_secctx(&entry->lsmblob, &context,
> +					     LSMBLOB_FIRST) == 0) {
>  			audit_log_format(audit_buf, " sec_obj=%s",
>  					 context.context);
>  			security_release_secctx(&context);
> @@ -1120,7 +1123,7 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
>  		lsmb = (struct lsmblob *)&addr6->lsmblob;
>  	}
>  
> -	ret_val = security_secid_to_secctx(lsmb, &context);
> +	ret_val = security_secid_to_secctx(lsmb, &context, LSMBLOB_FIRST);
>  	if (ret_val != 0)
>  		goto list_cb_failure;
>  	ret_val = nla_put(cb_arg->skb,
> diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
> index 951ba0639d20..1941877fd16f 100644
> --- a/net/netlabel/netlabel_user.c
> +++ b/net/netlabel/netlabel_user.c
> @@ -100,7 +100,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
>  
>  	lsmblob_init(&blob, audit_info->secid);
>  	if (audit_info->secid != 0 &&
> -	    security_secid_to_secctx(&blob, &context) == 0) {
> +	    security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST) == 0) {
>  		audit_log_format(audit_buf, " subj=%s", context.context);
>  		security_release_secctx(&context);
>  	}
> diff --git a/security/security.c b/security/security.c
> index 64073d807240..be6682768760 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2347,20 +2347,36 @@ EXPORT_SYMBOL(security_ismaclabel);
>   * security_secid_to_secctx - convert secid to secctx
>   * @blob: set of secids
>   * @cp: lsm context into which result is put
> + * @ilsm: which security module to report
>   *
>   * Translate secid information into a secctx string.
>   * Return a negative value on error.
>   * If cp is NULL return the length of the string.
>   * Otherwise, return 0.
>   */
> -int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
> +int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
> +			     int ilsm)
>  {
>  	struct security_hook_list *hp;
> -	int ilsm = lsm_task_ilsm(current);
>  
>  	if (cp)
>  		memset(cp, 0, sizeof(*cp));
>  
> +	/*
> +	 * ilsm either is the slot number use for formatting
> +	 * or an instruction on which relative slot to use.
> +	 */
> +	if (ilsm == LSMBLOB_DISPLAY)
> +		ilsm = lsm_task_ilsm(current);
> +	else if (ilsm == LSMBLOB_FIRST)
> +		ilsm = LSMBLOB_INVALID;
> +	else if (ilsm < 0) {
> +		WARN_ONCE(true, "LSM: %s unknown interface LSM\n", __func__);
> +		ilsm = LSMBLOB_INVALID;
> +	} else if (ilsm >= lsm_slot) {
> +		WARN_ONCE(true, "LSM: %s invalid interface LSM\n", __func__);
> +		ilsm = LSMBLOB_INVALID;
> +	}
>  	hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
>  		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
>  			continue;
diff mbox series

Patch

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 259f5e38e6ba..d59c4ebf7e22 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2983,7 +2983,7 @@  static void binder_transaction(struct binder_proc *proc,
 		size_t added_size;
 
 		security_cred_getsecid(proc->cred, &blob);
-		ret = security_secid_to_secctx(&blob, &lsmctx);
+		ret = security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_DISPLAY);
 		if (ret) {
 			return_error = BR_FAILED_REPLY;
 			return_error_param = ret;
diff --git a/include/linux/security.h b/include/linux/security.h
index dc66f3f48456..2150016492be 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -184,6 +184,8 @@  struct lsmblob {
 #define LSMBLOB_INVALID		-1	/* Not a valid LSM slot number */
 #define LSMBLOB_NEEDED		-2	/* Slot requested on initialization */
 #define LSMBLOB_NOT_NEEDED	-3	/* Slot not requested */
+#define LSMBLOB_DISPLAY		-4	/* Use the "interface_lsm" slot */
+#define LSMBLOB_FIRST		-5	/* Use the first slot */
 
 /**
  * lsmblob_init - initialize a lsmblob structure
@@ -615,7 +617,8 @@  int security_setprocattr(const char *lsm, const char *name, void *value,
 			 size_t size);
 int security_netlink_send(struct sock *sk, struct sk_buff *skb);
 int security_ismaclabel(const char *name);
-int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
+int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
+			     int ilsm);
 int security_secctx_to_secid(const char *secdata, u32 seclen,
 			     struct lsmblob *blob);
 void security_release_secctx(struct lsmcontext *cp);
@@ -1470,7 +1473,7 @@  static inline int security_ismaclabel(const char *name)
 }
 
 static inline int security_secid_to_secctx(struct lsmblob *blob,
-					   struct lsmcontext *cp)
+					   struct lsmcontext *cp, int ilsm)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/include/net/scm.h b/include/net/scm.h
index b77a52f93389..f4d567d4885e 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -101,7 +101,7 @@  static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
 		 * and the infrastructure will know which it is.
 		 */
 		lsmblob_init(&lb, scm->secid);
-		err = security_secid_to_secctx(&lb, &context);
+		err = security_secid_to_secctx(&lb, &context, LSMBLOB_DISPLAY);
 
 		if (!err) {
 			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, context.len,
diff --git a/kernel/audit.c b/kernel/audit.c
index a885ebdbb91e..28ff7a5f90bd 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1464,7 +1464,7 @@  static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 
 		if (lsmblob_is_set(&audit_sig_lsm)) {
 			err = security_secid_to_secctx(&audit_sig_lsm,
-						       &context);
+						       &context, LSMBLOB_FIRST);
 			if (err)
 				return err;
 		}
@@ -2176,7 +2176,7 @@  int audit_log_task_context(struct audit_buffer *ab)
 	if (!lsmblob_is_set(&blob))
 		return 0;
 
-	error = security_secid_to_secctx(&blob, &context);
+	error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST);
 
 	if (error) {
 		if (error != -EINVAL)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 802de65259d8..231631f61550 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1132,7 +1132,7 @@  static int audit_log_pid_context(struct audit_context *context, pid_t pid,
 			 from_kuid(&init_user_ns, auid),
 			 from_kuid(&init_user_ns, uid), sessionid);
 	if (lsmblob_is_set(blob)) {
-		if (security_secid_to_secctx(blob, &lsmctx)) {
+		if (security_secid_to_secctx(blob, &lsmctx, LSMBLOB_FIRST)) {
 			audit_log_format(ab, " obj=(none)");
 			rc = 1;
 		} else {
@@ -1425,7 +1425,8 @@  static void show_special(struct audit_context *context, int *call_panic)
 			struct lsmblob blob;
 
 			lsmblob_init(&blob, osid);
-			if (security_secid_to_secctx(&blob, &lsmcxt)) {
+			if (security_secid_to_secctx(&blob, &lsmcxt,
+						     LSMBLOB_FIRST)) {
 				audit_log_format(ab, " osid=%u", osid);
 				*call_panic = 1;
 			} else {
@@ -1593,7 +1594,7 @@  static void audit_log_name(struct audit_context *context, struct audit_names *n,
 		struct lsmcontext lsmctx;
 
 		lsmblob_init(&blob, n->osid);
-		if (security_secid_to_secctx(&blob, &lsmctx)) {
+		if (security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_FIRST)) {
 			audit_log_format(ab, " osid=%u", n->osid);
 			if (call_panic)
 				*call_panic = 2;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ad5be7707bca..9b5c44dec1e9 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -140,7 +140,7 @@  static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
 		return;
 
 	lsmblob_init(&lb, secid);
-	err = security_secid_to_secctx(&lb, &context);
+	err = security_secid_to_secctx(&lb, &context, LSMBLOB_DISPLAY);
 	if (err)
 		return;
 
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 07660c7dd342..5d72d2f41562 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -353,7 +353,7 @@  static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
 	 * security_secid_to_secctx() will know which security module
 	 * to use to create the secctx.  */
 	lsmblob_init(&blob, ct->secmark);
-	ret = security_secid_to_secctx(&blob, &context);
+	ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
 	if (ret)
 		return 0;
 
@@ -663,7 +663,7 @@  static inline int ctnetlink_secctx_size(const struct nf_conn *ct)
 	int len;
 	struct lsmblob blob;
 
-	len = security_secid_to_secctx(&blob, NULL);
+	len = security_secid_to_secctx(&blob, NULL, LSMBLOB_DISPLAY);
 	if (len <= 0)
 		return 0;
 
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 36338660df3c..cb4b8b636f6a 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -180,7 +180,7 @@  static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
 	struct lsmcontext context;
 
 	lsmblob_init(&blob, ct->secmark);
-	ret = security_secid_to_secctx(&blob, &context);
+	ret = security_secid_to_secctx(&blob, &context, LSMBLOB_DISPLAY);
 	if (ret)
 		return;
 
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index f60a0b6240ff..844955b2e163 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -316,7 +316,7 @@  static void nfqnl_get_sk_secctx(struct sk_buff *skb, struct lsmcontext *context)
 		 * blob. security_secid_to_secctx() will know which security
 		 * module to use to create the secctx.  */
 		lsmblob_init(&blob, skb->secmark);
-		security_secid_to_secctx(&blob, context);
+		security_secid_to_secctx(&blob, context, LSMBLOB_DISPLAY);
 	}
 
 	read_unlock_bh(&skb->sk->sk_callback_lock);
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 910a03f15b0d..8deee7e176a9 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -437,7 +437,8 @@  int netlbl_unlhsh_add(struct net *net,
 unlhsh_add_return:
 	rcu_read_unlock();
 	if (audit_buf != NULL) {
-		if (security_secid_to_secctx(lsmblob, &context) == 0) {
+		if (security_secid_to_secctx(lsmblob, &context,
+					     LSMBLOB_FIRST) == 0) {
 			audit_log_format(audit_buf, " sec_obj=%s",
 					 context.context);
 			security_release_secctx(&context);
@@ -491,7 +492,8 @@  static int netlbl_unlhsh_remove_addr4(struct net *net,
 					  addr->s_addr, mask->s_addr);
 		dev_put(dev);
 		if (entry != NULL &&
-		    security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
+		    security_secid_to_secctx(&entry->lsmblob, &context,
+					     LSMBLOB_FIRST) == 0) {
 			audit_log_format(audit_buf, " sec_obj=%s",
 					 context.context);
 			security_release_secctx(&context);
@@ -550,7 +552,8 @@  static int netlbl_unlhsh_remove_addr6(struct net *net,
 					  addr, mask);
 		dev_put(dev);
 		if (entry != NULL &&
-		    security_secid_to_secctx(&entry->lsmblob, &context) == 0) {
+		    security_secid_to_secctx(&entry->lsmblob, &context,
+					     LSMBLOB_FIRST) == 0) {
 			audit_log_format(audit_buf, " sec_obj=%s",
 					 context.context);
 			security_release_secctx(&context);
@@ -1120,7 +1123,7 @@  static int netlbl_unlabel_staticlist_gen(u32 cmd,
 		lsmb = (struct lsmblob *)&addr6->lsmblob;
 	}
 
-	ret_val = security_secid_to_secctx(lsmb, &context);
+	ret_val = security_secid_to_secctx(lsmb, &context, LSMBLOB_FIRST);
 	if (ret_val != 0)
 		goto list_cb_failure;
 	ret_val = nla_put(cb_arg->skb,
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 951ba0639d20..1941877fd16f 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -100,7 +100,7 @@  struct audit_buffer *netlbl_audit_start_common(int type,
 
 	lsmblob_init(&blob, audit_info->secid);
 	if (audit_info->secid != 0 &&
-	    security_secid_to_secctx(&blob, &context) == 0) {
+	    security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST) == 0) {
 		audit_log_format(audit_buf, " subj=%s", context.context);
 		security_release_secctx(&context);
 	}
diff --git a/security/security.c b/security/security.c
index 64073d807240..be6682768760 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2347,20 +2347,36 @@  EXPORT_SYMBOL(security_ismaclabel);
  * security_secid_to_secctx - convert secid to secctx
  * @blob: set of secids
  * @cp: lsm context into which result is put
+ * @ilsm: which security module to report
  *
  * Translate secid information into a secctx string.
  * Return a negative value on error.
  * If cp is NULL return the length of the string.
  * Otherwise, return 0.
  */
-int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
+int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp,
+			     int ilsm)
 {
 	struct security_hook_list *hp;
-	int ilsm = lsm_task_ilsm(current);
 
 	if (cp)
 		memset(cp, 0, sizeof(*cp));
 
+	/*
+	 * ilsm either is the slot number use for formatting
+	 * or an instruction on which relative slot to use.
+	 */
+	if (ilsm == LSMBLOB_DISPLAY)
+		ilsm = lsm_task_ilsm(current);
+	else if (ilsm == LSMBLOB_FIRST)
+		ilsm = LSMBLOB_INVALID;
+	else if (ilsm < 0) {
+		WARN_ONCE(true, "LSM: %s unknown interface LSM\n", __func__);
+		ilsm = LSMBLOB_INVALID;
+	} else if (ilsm >= lsm_slot) {
+		WARN_ONCE(true, "LSM: %s invalid interface LSM\n", __func__);
+		ilsm = LSMBLOB_INVALID;
+	}
 	hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
 		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
 			continue;