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From: Casey Schaufler <casey@schaufler-ca.com>
To: casey@schaufler-ca.com,
	paul@paul-moore.com,
	linux-security-module@vger.kernel.org
Cc: jmorris@namei.org,
	serge@hallyn.com,
	keescook@chromium.org,
	john.johansen@canonical.com,
	penguin-kernel@i-love.sakura.ne.jp,
	stephen.smalley.work@gmail.com,
	linux-kernel@vger.kernel.org,
	mic@digikod.net
Subject: [PATCH v39 26/42] Audit: Add record for multiple object contexts
Date: Fri, 15 Dec 2023 14:16:20 -0800
Message-ID: <20231215221636.105680-27-casey@schaufler-ca.com>
In-Reply-To: <20231215221636.105680-1-casey@schaufler-ca.com>
References: <20231215221636.105680-1-casey@schaufler-ca.com>
Precedence: bulk
MIME-Version: 1.0
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Create a new audit record AUDIT_MAC_OBJ_CONTEXTS.
An example of the MAC_OBJ_CONTEXTS (1421) record is:

    type=MAC_OBJ_CONTEXTS[1421]
    msg=audit(1601152467.009:1050):
    obj_selinux=unconfined_u:object_r:user_home_t:s0

When an audit event includes a AUDIT_MAC_OBJ_CONTEXTS record
the "obj=" field in other records in the event will be "obj=?".
An AUDIT_MAC_OBJ_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based
on an object security context.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Paul Moore <paul@paul-moore.com>
---
 include/linux/audit.h      |  5 +++
 include/uapi/linux/audit.h |  1 +
 kernel/audit.c             | 51 +++++++++++++++++++++++-
 kernel/auditsc.c           | 81 ++++++++++++--------------------------
 4 files changed, 82 insertions(+), 56 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 8974500f730f..914cfd563ce3 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -185,6 +185,8 @@ extern void		    audit_log_path_denied(int type,
 						  const char *operation);
 extern void		    audit_log_lost(const char *message);
 
+extern void audit_log_object_context(struct audit_buffer *ab,
+				     struct lsmblob *blob);
 extern int audit_log_subject_context(struct audit_buffer *ab,
 				     struct lsmblob *blob);
 extern int audit_log_task_context(struct audit_buffer *ab);
@@ -247,6 +249,9 @@ static inline void audit_log_key(struct audit_buffer *ab, char *key)
 { }
 static inline void audit_log_path_denied(int type, const char *operation)
 { }
+static inline  void audit_log_object_context(struct audit_buffer *ab,
+					     struct lsmblob *blob)
+{ }
 static inline int audit_log_subject_context(struct audit_buffer *ab,
 					    struct lsmblob *blob)
 {
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index dc045164b86b..bed324162a7c 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -144,6 +144,7 @@
 #define AUDIT_MAC_CALIPSO_ADD	1418	/* NetLabel: add CALIPSO DOI entry */
 #define AUDIT_MAC_CALIPSO_DEL	1419	/* NetLabel: del CALIPSO DOI entry */
 #define AUDIT_MAC_TASK_CONTEXTS	1420	/* Multiple LSM task contexts */
+#define AUDIT_MAC_OBJ_CONTEXTS	1421	/* Multiple LSM objext contexts */
 
 #define AUDIT_FIRST_KERN_ANOM_MSG   1700
 #define AUDIT_LAST_KERN_ANOM_MSG    1799
diff --git a/kernel/audit.c b/kernel/audit.c
index 626942c38bca..dc11dd4c41fc 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1105,7 +1105,6 @@ static int is_audit_feature_set(int i)
 	return af.features & AUDIT_FEATURE_TO_MASK(i);
 }
 
-
 static int audit_get_feature(struct sk_buff *skb)
 {
 	u32 seq;
@@ -2289,6 +2288,56 @@ int audit_log_task_context(struct audit_buffer *ab)
 }
 EXPORT_SYMBOL(audit_log_task_context);
 
+void audit_log_object_context(struct audit_buffer *ab, struct lsmblob *blob)
+{
+	int i;
+	int error;
+	bool space = false;
+	struct lsmcontext context;
+
+	if (lsm_blob_cnt < 2) {
+		error = security_lsmblob_to_secctx(blob, &context,
+						   LSM_ID_UNDEF);
+		if (error) {
+			if (error != -EINVAL)
+				goto error_path;
+			return;
+		}
+		audit_log_format(ab, " obj=%s", context.context);
+		security_release_secctx(&context);
+		return;
+	}
+	audit_log_format(ab, " obj=?");
+	error = audit_buffer_aux_new(ab, AUDIT_MAC_OBJ_CONTEXTS);
+	if (error)
+		goto error_path;
+
+	for (i = 0; i < lsm_blob_cnt; i++) {
+		if (!lsm_idlist[i]->lsmblob)
+			continue;
+		error = security_lsmblob_to_secctx(blob, &context,
+						   lsm_idlist[i]->id);
+		if (error) {
+			audit_log_format(ab, "%sobj_%s=?",
+					 space ? " " : "", lsm_idlist[i]->name);
+			if (error != -EINVAL)
+				audit_panic("error in audit_log_object_context");
+		} else {
+			audit_log_format(ab, "%sobj_%s=%s",
+					 space ? " " : "", lsm_idlist[i]->name,
+					 context.context);
+			security_release_secctx(&context);
+		}
+		space = true;
+	}
+
+	audit_buffer_aux_end(ab);
+	return;
+
+error_path:
+	audit_panic("error in audit_log_object_context");
+}
+
 void audit_log_d_path_exe(struct audit_buffer *ab,
 			  struct mm_struct *mm)
 {
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 23f72c14276d..bc13666dd6ed 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1092,36 +1092,27 @@ static inline void audit_free_context(struct audit_context *context)
 	kfree(context);
 }
 
-static int audit_log_pid_context(struct audit_context *context, pid_t pid,
-				 kuid_t auid, kuid_t uid,
-				 unsigned int sessionid, struct lsmblob *blob,
-				 char *comm)
+static void audit_log_pid_context(struct audit_context *context, pid_t pid,
+				  kuid_t auid, kuid_t uid,
+				  unsigned int sessionid, struct lsmblob *blob,
+				  char *comm)
 {
 	struct audit_buffer *ab;
-	struct lsmcontext ctx;
-	int rc = 0;
 
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
 	if (!ab)
-		return rc;
+		return;
 
 	audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", 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, LSM_ID_UNDEF) < 0) {
-			audit_log_format(ab, " obj=(none)");
-			rc = 1;
-		} else {
-			audit_log_format(ab, " obj=%s", ctx.context);
-			security_release_secctx(&ctx);
-		}
-	}
+	if (lsmblob_is_set(blob))
+		audit_log_object_context(ab, blob);
 	audit_log_format(ab, " ocomm=");
 	audit_log_untrustedstring(ab, comm);
 	audit_log_end(ab);
 
-	return rc;
+	return;
 }
 
 static void audit_log_execve_info(struct audit_context *context,
@@ -1370,7 +1361,6 @@ 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 lsmctx;
 	struct audit_buffer *ab;
 	int i;
 
@@ -1392,16 +1382,8 @@ static void show_special(struct audit_context *context, int *call_panic)
 				 from_kuid(&init_user_ns, context->ipc.uid),
 				 from_kgid(&init_user_ns, context->ipc.gid),
 				 context->ipc.mode);
-		if (lsmblob_is_set(&context->ipc.oblob)) {
-			if (security_lsmblob_to_secctx(&context->ipc.oblob,
-						       &lsmctx,
-						       LSM_ID_UNDEF) < 0) {
-				*call_panic = 1;
-			} else {
-				audit_log_format(ab, " obj=%s", lsmctx.context);
-				security_release_secctx(&lsmctx);
-			}
-		}
+		if (lsmblob_is_set(&context->ipc.oblob))
+			audit_log_object_context(ab, &context->ipc.oblob);
 		if (context->ipc.has_perm) {
 			audit_log_end(ab);
 			ab = audit_log_start(context, GFP_KERNEL,
@@ -1557,18 +1539,8 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
 				 from_kgid(&init_user_ns, n->gid),
 				 MAJOR(n->rdev),
 				 MINOR(n->rdev));
-	if (lsmblob_is_set(&n->oblob)) {
-		struct lsmcontext ctx;
-
-		if (security_lsmblob_to_secctx(&n->oblob, &ctx,
-					       LSM_ID_UNDEF) < 0) {
-			if (call_panic)
-				*call_panic = 2;
-		} else {
-			audit_log_format(ab, " obj=%s", ctx.context);
-			security_release_secctx(&ctx);
-		}
-	}
+	if (lsmblob_is_set(&n->oblob))
+		audit_log_object_context(ab, &n->oblob);
 
 	/* log the audit_names record type */
 	switch (n->type) {
@@ -1773,21 +1745,20 @@ static void audit_log_exit(void)
 		struct audit_aux_data_pids *axs = (void *)aux;
 
 		for (i = 0; i < axs->pid_count; i++)
-			if (audit_log_pid_context(context, axs->target_pid[i],
-						  axs->target_auid[i],
-						  axs->target_uid[i],
-						  axs->target_sessionid[i],
-						  &axs->target_blob[i],
-						  axs->target_comm[i]))
-				call_panic = 1;
-	}
-
-	if (context->target_pid &&
-	    audit_log_pid_context(context, context->target_pid,
-				  context->target_auid, context->target_uid,
-				  context->target_sessionid,
-				  &context->target_blob, context->target_comm))
-			call_panic = 1;
+			audit_log_pid_context(context, axs->target_pid[i],
+					      axs->target_auid[i],
+					      axs->target_uid[i],
+					      axs->target_sessionid[i],
+					      &axs->target_blob[i],
+					      axs->target_comm[i]);
+	}
+
+	if (context->target_pid)
+		audit_log_pid_context(context, context->target_pid,
+				      context->target_auid, context->target_uid,
+				      context->target_sessionid,
+				      &context->target_blob,
+				      context->target_comm);
 
 	if (context->pwd.dentry && context->pwd.mnt) {
 		ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
-- 
2.41.0