Thread (38 messages) 38 messages, 5 authors, 2021-02-23

[PATCH v24 16/25] LSM: Use lsmcontext in security_secid_to_secctx

From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2021-01-27 00:00:46
Also in: linux-security-module, lkml, netdev, netfilter-devel
Subsystem: android drivers, audit subsystem, netfilter, networking [general], networking [ipv4/ipv6], networking [labeled] (netlabel, labeled ipsec, secmark), security subsystem, the rest · Maintainers: Greg Kroah-Hartman, Arve Hjønnevåg, Todd Kjos, Christian Brauner, Carlos Llamas, Alice Ryhl, Paul Moore, Eric Paris, Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, James Morris, "Serge E. Hallyn", Linus Torvalds

Replace the (secctx,seclen) pointer pair with a single
lsmcontext pointer to allow return of the LSM identifier
along with the context and context length. This allows
security_release_secctx() to know how to release the
context. Callers have been modified to use or save the
returned data from the new structure.

Reviewed-by: Kees Cook <redacted>
Acked-by: Stephen Smalley <redacted>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: netdev@vger.kernel.org
Cc: linux-audit@redhat.com
Cc: netfilter-devel@vger.kernel.org
---
 drivers/android/binder.c                | 26 +++++++---------
 include/linux/security.h                |  4 +--
 include/net/scm.h                       |  9 ++----
 kernel/audit.c                          | 39 +++++++++++-------------
 kernel/auditsc.c                        | 31 +++++++------------
 net/ipv4/ip_sockglue.c                  |  8 ++---
 net/netfilter/nf_conntrack_netlink.c    | 18 +++++------
 net/netfilter/nf_conntrack_standalone.c |  7 ++---
 net/netfilter/nfnetlink_queue.c         |  5 +++-
 net/netlabel/netlabel_unlabeled.c       | 40 ++++++++-----------------
 net/netlabel/netlabel_user.c            |  7 ++---
 security/security.c                     | 10 +++++--
 12 files changed, 81 insertions(+), 123 deletions(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index f74a72867ec9..4c810ea52ab7 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2446,9 +2446,7 @@ static void binder_transaction(struct binder_proc *proc,
 	binder_size_t last_fixup_min_off = 0;
 	struct binder_context *context = proc->context;
 	int t_debug_id = atomic_inc_return(&binder_last_id);
-	char *secctx = NULL;
-	u32 secctx_sz = 0;
-	struct lsmcontext scaff; /* scaffolding */
+	struct lsmcontext lsmctx = { };
 
 	e = binder_transaction_log_add(&binder_transaction_log);
 	e->debug_id = t_debug_id;
@@ -2702,14 +2700,14 @@ static void binder_transaction(struct binder_proc *proc,
 		size_t added_size;
 
 		security_task_getsecid(proc->tsk, &blob);
-		ret = security_secid_to_secctx(&blob, &secctx, &secctx_sz);
+		ret = security_secid_to_secctx(&blob, &lsmctx);
 		if (ret) {
 			return_error = BR_FAILED_REPLY;
 			return_error_param = ret;
 			return_error_line = __LINE__;
 			goto err_get_secctx_failed;
 		}
-		added_size = ALIGN(secctx_sz, sizeof(u64));
+		added_size = ALIGN(lsmctx.len, sizeof(u64));
 		extra_buffers_size += added_size;
 		if (extra_buffers_size < added_size) {
 			/* integer overflow of extra_buffers_size */
@@ -2736,24 +2734,22 @@ static void binder_transaction(struct binder_proc *proc,
 		t->buffer = NULL;
 		goto err_binder_alloc_buf_failed;
 	}
-	if (secctx) {
+	if (lsmctx.context) {
 		int err;
 		size_t buf_offset = ALIGN(tr->data_size, sizeof(void *)) +
 				    ALIGN(tr->offsets_size, sizeof(void *)) +
 				    ALIGN(extra_buffers_size, sizeof(void *)) -
-				    ALIGN(secctx_sz, sizeof(u64));
+				    ALIGN(lsmctx.len, sizeof(u64));
 
 		t->security_ctx = (uintptr_t)t->buffer->user_data + buf_offset;
 		err = binder_alloc_copy_to_buffer(&target_proc->alloc,
 						  t->buffer, buf_offset,
-						  secctx, secctx_sz);
+						  lsmctx.context, lsmctx.len);
 		if (err) {
 			t->security_ctx = 0;
 			WARN_ON(1);
 		}
-		lsmcontext_init(&scaff, secctx, secctx_sz, 0);
-		security_release_secctx(&scaff);
-		secctx = NULL;
+		security_release_secctx(&lsmctx);
 	}
 	t->buffer->debug_id = t->debug_id;
 	t->buffer->transaction = t;
@@ -2810,7 +2806,7 @@ static void binder_transaction(struct binder_proc *proc,
 	off_end_offset = off_start_offset + tr->offsets_size;
 	sg_buf_offset = ALIGN(off_end_offset, sizeof(void *));
 	sg_buf_end_offset = sg_buf_offset + extra_buffers_size -
-		ALIGN(secctx_sz, sizeof(u64));
+		ALIGN(lsmctx.len, sizeof(u64));
 	off_min = 0;
 	for (buffer_offset = off_start_offset; buffer_offset < off_end_offset;
 	     buffer_offset += sizeof(binder_size_t)) {
@@ -3086,10 +3082,8 @@ static void binder_transaction(struct binder_proc *proc,
 	binder_alloc_free_buf(&target_proc->alloc, t->buffer);
 err_binder_alloc_buf_failed:
 err_bad_extra_size:
-	if (secctx) {
-		lsmcontext_init(&scaff, secctx, secctx_sz, 0);
-		security_release_secctx(&scaff);
-	}
+	if (lsmctx.context)
+		security_release_secctx(&lsmctx);
 err_get_secctx_failed:
 	kfree(tcomplete);
 	binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
diff --git a/include/linux/security.h b/include/linux/security.h
index cfa19eb9533b..ead44674cea2 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -564,7 +564,7 @@ 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, char **secdata, u32 *seclen);
+int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
 int security_secctx_to_secid(const char *secdata, u32 seclen,
 			     struct lsmblob *blob);
 void security_release_secctx(struct lsmcontext *cp);
@@ -1390,7 +1390,7 @@ static inline int security_ismaclabel(const char *name)
 }
 
 static inline int security_secid_to_secctx(struct lsmblob *blob,
-					   char **secdata, u32 *seclen)
+					   struct lsmcontext *cp)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/include/net/scm.h b/include/net/scm.h
index f273c4d777ec..b77a52f93389 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -94,8 +94,6 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
 {
 	struct lsmcontext context;
 	struct lsmblob lb;
-	char *secdata;
-	u32 seclen;
 	int err;
 
 	if (test_bit(SOCK_PASSSEC, &sock->flags)) {
@@ -103,12 +101,11 @@ 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, &secdata, &seclen);
+		err = security_secid_to_secctx(&lb, &context);
 
 		if (!err) {
-			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
-			/*scaffolding*/
-			lsmcontext_init(&context, secdata, seclen, 0);
+			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, context.len,
+				 context.context);
 			security_release_secctx(&context);
 		}
 	}
diff --git a/kernel/audit.c b/kernel/audit.c
index 902962ea9be6..ce90ea8373d3 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1190,9 +1190,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	struct audit_buffer	*ab;
 	u16			msg_type = nlh->nlmsg_type;
 	struct audit_sig_info   *sig_data;
-	char			*ctx = NULL;
-	u32			len;
-	struct lsmcontext	scaff; /* scaffolding */
 
 	err = audit_netlink_ok(skb, msg_type);
 	if (err)
@@ -1440,33 +1437,34 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		kfree(new);
 		break;
 	}
-	case AUDIT_SIGNAL_INFO:
-		len = 0;
+	case AUDIT_SIGNAL_INFO: {
+		struct lsmcontext context = { };
+		int len = 0;
+
 		if (lsmblob_is_set(&audit_sig_lsm)) {
-			err = security_secid_to_secctx(&audit_sig_lsm, &ctx,
-						       &len);
+			err = security_secid_to_secctx(&audit_sig_lsm,
+						       &context);
 			if (err)
 				return err;
 		}
-		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
+		sig_data = kmalloc(sizeof(*sig_data) + context.len, GFP_KERNEL);
 		if (!sig_data) {
-			if (lsmblob_is_set(&audit_sig_lsm)) {
-				lsmcontext_init(&scaff, ctx, len, 0);
-				security_release_secctx(&scaff);
-			}
+			if (lsmblob_is_set(&audit_sig_lsm))
+				security_release_secctx(&context);
 			return -ENOMEM;
 		}
 		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
 		sig_data->pid = audit_sig_pid;
 		if (lsmblob_is_set(&audit_sig_lsm)) {
-			memcpy(sig_data->ctx, ctx, len);
-			lsmcontext_init(&scaff, ctx, len, 0);
-			security_release_secctx(&scaff);
+			len = context.len;
+			memcpy(sig_data->ctx, context.context, len);
+			security_release_secctx(&context);
 		}
 		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
 				 sig_data, sizeof(*sig_data) + len);
 		kfree(sig_data);
 		break;
+	}
 	case AUDIT_TTY_GET: {
 		struct audit_tty_status s;
 		unsigned int t;
@@ -2132,26 +2130,23 @@ void audit_log_key(struct audit_buffer *ab, char *key)
 
 int audit_log_task_context(struct audit_buffer *ab)
 {
-	char *ctx = NULL;
-	unsigned len;
 	int error;
 	struct lsmblob blob;
-	struct lsmcontext scaff; /* scaffolding */
+	struct lsmcontext context;
 
 	security_task_getsecid(current, &blob);
 	if (!lsmblob_is_set(&blob))
 		return 0;
 
-	error = security_secid_to_secctx(&blob, &ctx, &len);
+	error = security_secid_to_secctx(&blob, &context);
 	if (error) {
 		if (error != -EINVAL)
 			goto error_path;
 		return 0;
 	}
 
-	audit_log_format(ab, " subj=%s", ctx);
-	lsmcontext_init(&scaff, ctx, len, 0);
-	security_release_secctx(&scaff);
+	audit_log_format(ab, " subj=%s", context.context);
+	security_release_secctx(&context);
 	return 0;
 
 error_path:
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index a73253515bc9..de2b2ecb3aea 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -998,9 +998,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
 				 struct lsmblob *blob, char *comm)
 {
 	struct audit_buffer *ab;
-	struct lsmcontext lsmcxt;
-	char *ctx = NULL;
-	u32 len;
+	struct lsmcontext lsmctx;
 	int rc = 0;
 
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
@@ -1011,13 +1009,12 @@ 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, &ctx, &len)) {
+		if (security_secid_to_secctx(blob, &lsmctx)) {
 			audit_log_format(ab, " obj=(none)");
 			rc = 1;
 		} else {
-			audit_log_format(ab, " obj=%s", ctx);
-			lsmcontext_init(&lsmcxt, ctx, len, 0); /*scaffolding*/
-			security_release_secctx(&lsmcxt);
+			audit_log_format(ab, " obj=%s", lsmctx.context);
+			security_release_secctx(&lsmctx);
 		}
 	}
 	audit_log_format(ab, " ocomm=");
@@ -1230,7 +1227,6 @@ static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
 
 static void show_special(struct audit_context *context, int *call_panic)
 {
-	struct lsmcontext lsmcxt;
 	struct audit_buffer *ab;
 	int i;
 
@@ -1254,17 +1250,15 @@ static void show_special(struct audit_context *context, int *call_panic)
 				 from_kgid(&init_user_ns, context->ipc.gid),
 				 context->ipc.mode);
 		if (osid) {
-			char *ctx = NULL;
-			u32 len;
+			struct lsmcontext lsmcxt;
 			struct lsmblob blob;
 
 			lsmblob_init(&blob, osid);
-			if (security_secid_to_secctx(&blob, &ctx, &len)) {
+			if (security_secid_to_secctx(&blob, &lsmcxt)) {
 				audit_log_format(ab, " osid=%u", osid);
 				*call_panic = 1;
 			} else {
-				audit_log_format(ab, " obj=%s", ctx);
-				lsmcontext_init(&lsmcxt, ctx, len, 0);
+				audit_log_format(ab, " obj=%s", lsmcxt.context);
 				security_release_secctx(&lsmcxt);
 			}
 		}
@@ -1411,20 +1405,17 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
 				 MAJOR(n->rdev),
 				 MINOR(n->rdev));
 	if (n->osid != 0) {
-		char *ctx = NULL;
-		u32 len;
 		struct lsmblob blob;
-		struct lsmcontext lsmcxt;
+		struct lsmcontext lsmctx;
 
 		lsmblob_init(&blob, n->osid);
-		if (security_secid_to_secctx(&blob, &ctx, &len)) {
+		if (security_secid_to_secctx(&blob, &lsmctx)) {
 			audit_log_format(ab, " osid=%u", n->osid);
 			if (call_panic)
 				*call_panic = 2;
 		} else {
-			audit_log_format(ab, " obj=%s", ctx);
-			lsmcontext_init(&lsmcxt, ctx, len, 0); /* scaffolding */
-			security_release_secctx(&lsmcxt);
+			audit_log_format(ab, " obj=%s", lsmctx.context);
+			security_release_secctx(&lsmctx);
 		}
 	}
 
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index a7e4c1b34b6c..ae073b642fa7 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -132,8 +132,7 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
 {
 	struct lsmcontext context;
 	struct lsmblob lb;
-	char *secdata;
-	u32 seclen, secid;
+	u32 secid;
 	int err;
 
 	err = security_socket_getpeersec_dgram(NULL, skb, &secid);
@@ -141,12 +140,11 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
 		return;
 
 	lsmblob_init(&lb, secid);
-	err = security_secid_to_secctx(&lb, &secdata, &seclen);
+	err = security_secid_to_secctx(&lb, &context);
 	if (err)
 		return;
 
-	put_cmsg(msg, SOL_IP, SCM_SECURITY, seclen, secdata);
-	lsmcontext_init(&context, secdata, seclen, 0); /* scaffolding */
+	put_cmsg(msg, SOL_IP, SCM_SECURITY, context.len, context.context);
 	security_release_secctx(&context);
 }
 
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 3b9cf2a1fed7..42570b8da17a 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -336,8 +336,7 @@ static int ctnetlink_dump_mark(struct sk_buff *skb, const struct nf_conn *ct)
 static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
 {
 	struct nlattr *nest_secctx;
-	int len, ret;
-	char *secctx;
+	int ret;
 	struct lsmblob blob;
 	struct lsmcontext context;
 
@@ -345,7 +344,7 @@ 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, &secctx, &len);
+	ret = security_secid_to_secctx(&blob, &context);
 	if (ret)
 		return 0;
 
@@ -354,13 +353,12 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
 	if (!nest_secctx)
 		goto nla_put_failure;
 
-	if (nla_put_string(skb, CTA_SECCTX_NAME, secctx))
+	if (nla_put_string(skb, CTA_SECCTX_NAME, context.context))
 		goto nla_put_failure;
 	nla_nest_end(skb, nest_secctx);
 
 	ret = 0;
 nla_put_failure:
-	lsmcontext_init(&context, secctx, len, 0); /* scaffolding */
 	security_release_secctx(&context);
 	return ret;
 }
@@ -660,15 +658,15 @@ static inline int ctnetlink_secctx_size(const struct nf_conn *ct)
 #ifdef CONFIG_NF_CONNTRACK_SECMARK
 	int len, ret;
 	struct lsmblob blob;
+	struct lsmcontext context;
 
-	/* lsmblob_init() puts ct->secmark into all of the secids in blob.
-	 * 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, NULL, &len);
+	ret = security_secid_to_secctx(&blob, &context);
 	if (ret)
 		return 0;
 
+	len = context.len;
+	security_release_secctx(&context);
+
 	return nla_total_size(0) /* CTA_SECCTX */
 	       + nla_total_size(sizeof(char) * len); /* CTA_SECCTX_NAME */
 #else
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index e2bdc851a477..c6112960fc73 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -173,19 +173,16 @@ static void ct_seq_stop(struct seq_file *s, void *v)
 static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
 {
 	int ret;
-	u32 len;
-	char *secctx;
 	struct lsmblob blob;
 	struct lsmcontext context;
 
 	lsmblob_init(&blob, ct->secmark);
-	ret = security_secid_to_secctx(&blob, &secctx, &len);
+	ret = security_secid_to_secctx(&blob, &context);
 	if (ret)
 		return;
 
-	seq_printf(s, "secctx=%s ", secctx);
+	seq_printf(s, "secctx=%s ", context.context);
 
-	lsmcontext_init(&context, secctx, len, 0); /* scaffolding */
 	security_release_secctx(&context);
 }
 #else
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index dcc31cb7f287..84be5a49a157 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -306,6 +306,7 @@ static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
 	u32 seclen = 0;
 #if IS_ENABLED(CONFIG_NETWORK_SECMARK)
 	struct lsmblob blob;
+	struct lsmcontext context = { };
 
 	if (!skb || !sk_fullsock(skb->sk))
 		return 0;
@@ -317,10 +318,12 @@ static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
 		 * 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, secdata, &seclen);
+		security_secid_to_secctx(&blob, &context);
+		*secdata = context.context;
 	}
 
 	read_unlock_bh(&skb->sk->sk_callback_lock);
+	seclen = context.len;
 #endif
 	return seclen;
 }
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 32b6eea7ba0c..aa53a94115f4 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -375,8 +375,6 @@ int netlbl_unlhsh_add(struct net *net,
 	struct netlbl_unlhsh_iface *iface;
 	struct audit_buffer *audit_buf = NULL;
 	struct lsmcontext context;
-	char *secctx = NULL;
-	u32 secctx_len;
 	struct lsmblob blob;
 
 	if (addr_len != sizeof(struct in_addr) &&
@@ -444,12 +442,9 @@ int netlbl_unlhsh_add(struct net *net,
 		 * security_secid_to_secctx() will know which security module
 		 * to use to create the secctx.  */
 		lsmblob_init(&blob, secid);
-		if (security_secid_to_secctx(&blob,
-					     &secctx,
-					     &secctx_len) == 0) {
-			audit_log_format(audit_buf, " sec_obj=%s", secctx);
-			/* scaffolding */
-			lsmcontext_init(&context, secctx, secctx_len, 0);
+		if (security_secid_to_secctx(&blob, &context) == 0) {
+			audit_log_format(audit_buf, " sec_obj=%s",
+					 context.context);
 			security_release_secctx(&context);
 		}
 		audit_log_format(audit_buf, " res=%u", ret_val == 0 ? 1 : 0);
@@ -482,8 +477,6 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
 	struct audit_buffer *audit_buf;
 	struct net_device *dev;
 	struct lsmcontext context;
-	char *secctx;
-	u32 secctx_len;
 	struct lsmblob blob;
 
 	spin_lock(&netlbl_unlhsh_lock);
@@ -510,11 +503,9 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
 		if (entry != NULL)
 			lsmblob_init(&blob, entry->secid);
 		if (entry != NULL &&
-		    security_secid_to_secctx(&blob,
-					     &secctx, &secctx_len) == 0) {
-			audit_log_format(audit_buf, " sec_obj=%s", secctx);
-			/* scaffolding */
-			lsmcontext_init(&context, secctx, secctx_len, 0);
+		    security_secid_to_secctx(&blob, &context) == 0) {
+			audit_log_format(audit_buf, " sec_obj=%s",
+					 context.context);
 			security_release_secctx(&context);
 		}
 		audit_log_format(audit_buf, " res=%u", entry != NULL ? 1 : 0);
@@ -553,8 +544,6 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
 	struct audit_buffer *audit_buf;
 	struct net_device *dev;
 	struct lsmcontext context;
-	char *secctx;
-	u32 secctx_len;
 	struct lsmblob blob;
 
 	spin_lock(&netlbl_unlhsh_lock);
@@ -580,10 +569,9 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
 		if (entry != NULL)
 			lsmblob_init(&blob, entry->secid);
 		if (entry != NULL &&
-		    security_secid_to_secctx(&blob,
-					     &secctx, &secctx_len) == 0) {
-			audit_log_format(audit_buf, " sec_obj=%s", secctx);
-			lsmcontext_init(&context, secctx, secctx_len, 0);
+		    security_secid_to_secctx(&blob, &context) == 0) {
+			audit_log_format(audit_buf, " sec_obj=%s",
+					 context.context);
 			security_release_secctx(&context);
 		}
 		audit_log_format(audit_buf, " res=%u", entry != NULL ? 1 : 0);
@@ -1106,8 +1094,6 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
 	struct lsmcontext context;
 	void *data;
 	u32 secid;
-	char *secctx;
-	u32 secctx_len;
 	struct lsmblob blob;
 
 	data = genlmsg_put(cb_arg->skb, NETLINK_CB(cb_arg->nl_cb->skb).portid,
@@ -1167,15 +1153,13 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
 	 * security_secid_to_secctx() will know which security module
 	 * to use to create the secctx.  */
 	lsmblob_init(&blob, secid);
-	ret_val = security_secid_to_secctx(&blob, &secctx, &secctx_len);
+	ret_val = security_secid_to_secctx(&blob, &context);
 	if (ret_val != 0)
 		goto list_cb_failure;
 	ret_val = nla_put(cb_arg->skb,
 			  NLBL_UNLABEL_A_SECCTX,
-			  secctx_len,
-			  secctx);
-	/* scaffolding */
-	lsmcontext_init(&context, secctx, secctx_len, 0);
+			  context.len,
+			  context.context);
 	security_release_secctx(&context);
 	if (ret_val != 0)
 		goto list_cb_failure;
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index ef139d8ae7cd..951ba0639d20 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -85,8 +85,6 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 {
 	struct audit_buffer *audit_buf;
 	struct lsmcontext context;
-	char *secctx;
-	u32 secctx_len;
 	struct lsmblob blob;
 
 	if (audit_enabled == AUDIT_OFF)
@@ -102,9 +100,8 @@ 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, &secctx, &secctx_len) == 0) {
-		audit_log_format(audit_buf, " subj=%s", secctx);
-		lsmcontext_init(&context, secctx, secctx_len, 0);/*scaffolding*/
+	    security_secid_to_secctx(&blob, &context) == 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 904ae6c46be0..aab6d3f86e4a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2252,18 +2252,22 @@ int security_ismaclabel(const char *name)
 }
 EXPORT_SYMBOL(security_ismaclabel);
 
-int security_secid_to_secctx(struct lsmblob *blob, char **secdata, u32 *seclen)
+int security_secid_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
 {
 	struct security_hook_list *hp;
 	int ilsm = lsm_task_ilsm(current);
 
+	memset(cp, 0, sizeof(*cp));
+
 	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;
-		if (ilsm == LSMBLOB_INVALID || ilsm == hp->lsmid->slot)
+		if (ilsm == LSMBLOB_INVALID || ilsm == hp->lsmid->slot) {
+			cp->slot = hp->lsmid->slot;
 			return hp->hook.secid_to_secctx(
 					blob->secid[hp->lsmid->slot],
-					secdata, seclen);
+					&cp->context, &cp->len);
+		}
 	}
 
 	return LSM_RET_DEFAULT(secid_to_secctx);
-- 
2.25.4
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