[PATCH v39 18/42] LSM: Use lsmcontext in security_lsmblob_to_secctx

[Casey Schaufler <casey@schaufler-ca.com>]

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.

security_lsmblob_to_secctx() will now return the length value
on success instead of 0.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: netdev@vger.kernel.org
Cc: audit@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org
Cc: Todd Kjos <tkjos@google.com>
---
 include/linux/lsm_hook_defs.h     |  2 +-
 include/linux/security.h          |  5 ++---
 kernel/audit.c                    |  9 ++++-----
 kernel/auditsc.c                  | 17 ++++++-----------
 net/netlabel/netlabel_user.c      |  3 +--
 security/apparmor/include/secid.h |  3 +--
 security/apparmor/secid.c         | 14 ++++++++------
 security/security.c               | 24 +++++++++++-------------
 security/selinux/hooks.c          | 18 +++++++++++++++---
 security/smack/smack_lsm.c        | 16 ++++++++++------
 10 files changed, 59 insertions(+), 52 deletions(-)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 8e0155ac6697..339a4559daf8 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -275,7 +275,7 @@ LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size)
 LSM_HOOK(int, 0, ismaclabel, const char *name)
 LSM_HOOK(int, -EOPNOTSUPP, secid_to_secctx, u32 secid, struct lsmcontext *cp)
 LSM_HOOK(int, -EOPNOTSUPP, lsmblob_to_secctx, struct lsmblob *blob,
-	 char **secdata, u32 *seclen)
+	 struct lsmcontext *cp)
 LSM_HOOK(int, 0, secctx_to_secid, const char *secdata, u32 seclen, u32 *secid)
 LSM_HOOK(void, LSM_RET_VOID, release_secctx, struct lsmcontext *cp)
 LSM_HOOK(void, LSM_RET_VOID, inode_invalidate_secctx, struct inode *inode)
diff --git a/include/linux/security.h b/include/linux/security.h
index 03b79089eaf7..2a0615a62125 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -563,8 +563,7 @@ int security_setprocattr(int lsmid, 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(u32 secid, struct lsmcontext *cp);
-int security_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-			       u32 *seclen);
+int security_lsmblob_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
 int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void security_release_secctx(struct lsmcontext *cp);
 void security_inode_invalidate_secctx(struct inode *inode);
@@ -1493,7 +1492,7 @@ static inline int security_secid_to_secctx(u32 secid, struct lsmcontext *cp)
 }
 
 static inline int security_lsmblob_to_secctx(struct lsmblob *blob,
-					     char **secdata, u32 *seclen)
+					     struct lsmcontext *cp)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/kernel/audit.c b/kernel/audit.c
index 47cfb6b20c3c..a93a710c980e 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1462,9 +1462,8 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 
 		if (lsmblob_is_set(&audit_sig_lsm)) {
 			err = security_lsmblob_to_secctx(&audit_sig_lsm,
-							 &lsmctx.context,
-							 &lsmctx.len);
-			if (err)
+							 &lsmctx);
+			if (err < 0)
 				return err;
 		}
 		sig_data_size = struct_size(sig_data, ctx, lsmctx.len);
@@ -2175,8 +2174,8 @@ int audit_log_task_context(struct audit_buffer *ab)
 	if (!lsmblob_is_set(&blob))
 		return 0;
 
-	error = security_lsmblob_to_secctx(&blob, &ctx.context, &ctx.len);
-	if (error) {
+	error = security_lsmblob_to_secctx(&blob, &ctx);
+	if (error < 0) {
 		if (error != -EINVAL)
 			goto error_path;
 		return 0;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 2874255f5f25..c37cc02ea4cc 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1109,7 +1109,7 @@ 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_lsmblob_to_secctx(blob, &ctx.context, &ctx.len)) {
+		if (security_lsmblob_to_secctx(blob, &ctx) < 0) {
 			audit_log_format(ab, " obj=(none)");
 			rc = 1;
 		} else {
@@ -1370,7 +1370,7 @@ static void audit_log_time(struct audit_context *context, struct audit_buffer **
 
 static void show_special(struct audit_context *context, int *call_panic)
 {
-	struct lsmcontext lsmcxt;
+	struct lsmcontext lsmctx;
 	struct audit_buffer *ab;
 	int i;
 
@@ -1393,16 +1393,12 @@ static void show_special(struct audit_context *context, int *call_panic)
 				 from_kgid(&init_user_ns, context->ipc.gid),
 				 context->ipc.mode);
 		if (lsmblob_is_set(&context->ipc.oblob)) {
-			char *ctx = NULL;
-			u32 len;
-
 			if (security_lsmblob_to_secctx(&context->ipc.oblob,
-						       &ctx, &len)) {
+						       &lsmctx) < 0) {
 				*call_panic = 1;
 			} else {
-				audit_log_format(ab, " obj=%s", ctx);
-				lsmcontext_init(&lsmcxt, ctx, len, 0);
-				security_release_secctx(&lsmcxt);
+				audit_log_format(ab, " obj=%s", lsmctx.context);
+				security_release_secctx(&lsmctx);
 			}
 		}
 		if (context->ipc.has_perm) {
@@ -1563,8 +1559,7 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
 	if (lsmblob_is_set(&n->oblob)) {
 		struct lsmcontext ctx;
 
-		if (security_lsmblob_to_secctx(&n->oblob, &ctx.context,
-					       &ctx.len)) {
+		if (security_lsmblob_to_secctx(&n->oblob, &ctx) < 0) {
 			if (call_panic)
 				*call_panic = 2;
 		} else {
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index b9289a22b363..561e1e476a49 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -98,8 +98,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 			 audit_info->sessionid);
 
 	if (lsmblob_is_set(&audit_info->blob) &&
-	    security_lsmblob_to_secctx(&audit_info->blob, &ctx.context,
-				       &ctx.len) == 0) {
+	    security_lsmblob_to_secctx(&audit_info->blob, &ctx) >= 0) {
 		audit_log_format(audit_buf, " subj=%s", ctx.context);
 		security_release_secctx(&ctx);
 	}
diff --git a/security/apparmor/include/secid.h b/security/apparmor/include/secid.h
index b66c2d043a02..568820a11efc 100644
--- a/security/apparmor/include/secid.h
+++ b/security/apparmor/include/secid.h
@@ -26,8 +26,7 @@ extern int apparmor_display_secid_mode;
 
 struct aa_label *aa_secid_to_label(u32 secid);
 int apparmor_secid_to_secctx(u32 secid, struct lsmcontext *cp);
-int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-			       u32 *seclen);
+int apparmor_lsmblob_to_secctx(struct lsmblob *blob, struct lsmcontext *cp);
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void apparmor_release_secctx(struct lsmcontext *cp);
 
diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c
index 55d6c54fe90e..c9b9a8d90afa 100644
--- a/security/apparmor/secid.c
+++ b/security/apparmor/secid.c
@@ -93,8 +93,7 @@ int apparmor_secid_to_secctx(u32 secid, struct lsmcontext *cp)
 	return len;
 }
 
-int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-			       u32 *seclen)
+int apparmor_lsmblob_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
 {
 	/* TODO: cache secctx and ref count so we don't have to recreate */
 	struct aa_label *label;
@@ -115,8 +114,8 @@ int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
 	if (apparmor_display_secid_mode)
 		flags |= FLAG_SHOW_MODE;
 
-	if (secdata)
-		len = aa_label_asxprint(secdata, root_ns, label,
+	if (cp)
+		len = aa_label_asxprint(&cp->context, root_ns, label,
 					flags, GFP_ATOMIC);
 	else
 		len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
@@ -124,9 +123,12 @@ int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
 	if (len < 0)
 		return -ENOMEM;
 
-	*seclen = len;
+	if (cp) {
+		cp->len = len;
+		cp->id = LSM_ID_APPARMOR;
+	}
 
-	return 0;
+	return len;
 }
 
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
diff --git a/security/security.c b/security/security.c
index 708a26a88447..e070a6cd4089 100644
--- a/security/security.c
+++ b/security/security.c
@@ -4203,30 +4203,28 @@ EXPORT_SYMBOL(security_secid_to_secctx);
 /**
  * security_lsmblob_to_secctx() - Convert a lsmblob to a secctx
  * @blob: lsm specific information
- * @secdata: secctx
- * @seclen: secctx length
+ * @cp: the LSM context
  *
- * Convert a @blob entry to security context.  If @secdata is NULL the
- * length of the result will be returned in @seclen, but no @secdata
- * will be returned.  This does mean that the length could change between
- * calls to check the length and the next call which actually allocates
- * and returns the @secdata.
+ * Convert a @blob entry to security context. If @cp is NULL the
+ * length of the result will be returned, but no data will be returned.
+ * This does mean that the length could change between calls to check
+ * the length and the next call which actually allocates and returns
+ * the data.
  *
- * Return: Return 0 on success, error on failure.
+ * Return: Return length of data on success, error on failure.
  */
-int security_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-			       u32 *seclen)
+int security_lsmblob_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
 {
 	struct security_hook_list *hp;
 	int rc;
 
 	hlist_for_each_entry(hp, &security_hook_heads.lsmblob_to_secctx, list) {
-		rc = hp->hook.lsmblob_to_secctx(blob, secdata, seclen);
-		if (rc != LSM_RET_DEFAULT(secid_to_secctx))
+		rc = hp->hook.lsmblob_to_secctx(blob, cp);
+		if (rc != LSM_RET_DEFAULT(lsmblob_to_secctx))
 			return rc;
 	}
 
-	return LSM_RET_DEFAULT(secid_to_secctx);
+	return LSM_RET_DEFAULT(lsmblob_to_secctx);
 }
 EXPORT_SYMBOL(security_lsmblob_to_secctx);
 
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 37b97cf81da1..d138aa692abd 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6583,16 +6583,28 @@ static int selinux_secid_to_secctx(u32 secid, struct lsmcontext *cp)
 	return seclen;
 }
 
-static int selinux_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-				     u32 *seclen)
+static int selinux_lsmblob_to_secctx(struct lsmblob *blob,
+				     struct lsmcontext *cp)
 {
 	u32 secid = blob->selinux.secid;
+	u32 seclen;
+	u32 ret;
 
 	/* stacking scaffolding */
 	if (!secid)
 		secid = blob->scaffold.secid;
 
-	return security_sid_to_context(secid, secdata, seclen);
+	if (cp) {
+		cp->id = LSM_ID_SELINUX;
+		ret = security_sid_to_context(secid, &cp->context, &cp->len);
+		if (ret < 0)
+			return ret;
+		return cp->len;
+	}
+	ret = security_sid_to_context(secid, NULL, &seclen);
+	if (ret < 0)
+		return ret;
+	return seclen;
 }
 
 static int selinux_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d82753bc52ab..1fdd4233a9b3 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4839,19 +4839,23 @@ static int smack_secid_to_secctx(u32 secid, struct lsmcontext *cp)
  *
  * Exists for audit code.
  */
-static int smack_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
-				   u32 *seclen)
+static int smack_lsmblob_to_secctx(struct lsmblob *blob, struct lsmcontext *cp)
 {
 	struct smack_known *skp = blob->smack.skp;
+	int len;
 
 	/* stacking scaffolding */
 	if (!skp && blob->scaffold.secid)
 		skp = smack_from_secid(blob->scaffold.secid);
 
-	if (secdata)
-		*secdata = skp->smk_known;
-	*seclen = strlen(skp->smk_known);
-	return 0;
+	len = strlen(skp->smk_known);
+
+	if (cp) {
+		cp->context = skp->smk_known;
+		cp->len = len;
+		cp->id = LSM_ID_SMACK;
+	}
+	return len;
 }
 
 /**
-- 
2.41.0