[PATCH v23 03/23] LSM: Use lsmblob in security_audit_rule_match

From: Casey Schaufler <casey@schaufler-ca.com>
To: casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: casey@schaufler-ca.com, linux-audit@redhat.com,
	keescook@chromium.org, john.johansen@canonical.com,
	penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com,
	sds@tycho.nsa.gov, linux-kernel@vger.kernel.org,
	linux-integrity@vger.kernel.org
Subject: [PATCH v23 03/23] LSM: Use lsmblob in security_audit_rule_match
Date: Fri, 20 Nov 2020 12:14:47 -0800	[thread overview]
Message-ID: <20201120201507.11993-4-casey@schaufler-ca.com> (raw)
In-Reply-To: <20201120201507.11993-1-casey@schaufler-ca.com>

Change the secid parameter of security_audit_rule_match
to a lsmblob structure pointer. Pass the entry from the
lsmblob structure for the approprite slot to the LSM hook.

Change the users of security_audit_rule_match to use the
lsmblob instead of a u32. The scaffolding function lsmblob_init()
fills the blob with the value of the old secid, ensuring that
it is available to the appropriate module hook. The sources of
the secid, security_task_getsecid() and security_inode_getsecid(),
will be converted to use the blob structure later in the series.
At the point the use of lsmblob_init() is dropped.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: linux-audit@redhat.com
Cc: linux-integrity@vger.kernel.org
To: Mimi Zohar <zohar@linux.ibm.com
---
 include/linux/security.h            |  7 ++++---
 kernel/auditfilter.c                |  6 ++++--
 kernel/auditsc.c                    | 14 ++++++++++----
 security/integrity/ima/ima.h        |  4 ++--
 security/integrity/ima/ima_policy.c |  7 +++++--
 security/security.c                 | 10 ++++++++--
 6 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index fdb6e95c98e8..89c538aa283e 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1892,7 +1892,8 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)
 #ifdef CONFIG_SECURITY
 int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule);
 int security_audit_rule_known(struct audit_krule *krule);
-int security_audit_rule_match(u32 secid, u32 field, u32 op, void **lsmrule);
+int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
+			      void **lsmrule);
 void security_audit_rule_free(void **lsmrule);
 
 #else
@@ -1908,8 +1909,8 @@ static inline int security_audit_rule_known(struct audit_krule *krule)
 	return 0;
 }
 
-static inline int security_audit_rule_match(u32 secid, u32 field, u32 op,
-					    void **lsmrule)
+static inline int security_audit_rule_match(struct lsmblob *blob, u32 field,
+					    u32 op, void **lsmrule)
 {
 	return 0;
 }
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 45da229f9f1f..e27424216159 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1331,6 +1331,7 @@ int audit_filter(int msgtype, unsigned int listtype)
 			struct audit_field *f = &e->rule.fields[i];
 			pid_t pid;
 			u32 sid;
+			struct lsmblob blob;
 
 			switch (f->type) {
 			case AUDIT_PID:
@@ -1361,8 +1362,9 @@ int audit_filter(int msgtype, unsigned int listtype)
 			case AUDIT_SUBJ_CLR:
 				if (f->lsm_isset) {
 					security_task_getsecid(current, &sid);
-					result = security_audit_rule_match(sid,
-						   f->type, f->op,
+					lsmblob_init(&blob, sid);
+					result = security_audit_rule_match(
+						   &blob, f->type, f->op,
 						   f->lsm_rules);
 				}
 				break;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 16e3430f7d07..7dd6b815a9eb 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -474,6 +474,7 @@ static int audit_filter_rules(struct task_struct *tsk,
 	const struct cred *cred;
 	int i, need_sid = 1;
 	u32 sid;
+	struct lsmblob blob;
 	unsigned int sessionid;
 
 	cred = rcu_dereference_check(tsk->cred, tsk == current || task_creation);
@@ -672,7 +673,9 @@ static int audit_filter_rules(struct task_struct *tsk,
 					security_task_getsecid(tsk, &sid);
 					need_sid = 0;
 				}
-				result = security_audit_rule_match(sid, f->type,
+				lsmblob_init(&blob, sid);
+				result = security_audit_rule_match(&blob,
+								   f->type,
 								   f->op,
 								   f->lsm_rules);
 			}
@@ -687,15 +690,17 @@ static int audit_filter_rules(struct task_struct *tsk,
 			if (f->lsm_isset) {
 				/* Find files that match */
 				if (name) {
+					lsmblob_init(&blob, name->osid);
 					result = security_audit_rule_match(
-								name->osid,
+								&blob,
 								f->type,
 								f->op,
 								f->lsm_rules);
 				} else if (ctx) {
 					list_for_each_entry(n, &ctx->names_list, list) {
+						lsmblob_init(&blob, name->osid);
 						if (security_audit_rule_match(
-								n->osid,
+								&blob,
 								f->type,
 								f->op,
 								f->lsm_rules)) {
@@ -707,7 +712,8 @@ static int audit_filter_rules(struct task_struct *tsk,
 				/* Find ipc objects that match */
 				if (!ctx || ctx->type != AUDIT_IPC)
 					break;
-				if (security_audit_rule_match(ctx->ipc.osid,
+				lsmblob_init(&blob, ctx->ipc.osid);
+				if (security_audit_rule_match(&blob,
 							      f->type, f->op,
 							      f->lsm_rules))
 					++result;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 6ebefec616e4..6bae2ee9b251 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -429,8 +429,8 @@ static inline void ima_filter_rule_free(void *lsmrule)
 {
 }
 
-static inline int ima_filter_rule_match(u32 secid, u32 field, u32 op,
-					void *lsmrule)
+static inline int ima_filter_rule_match(struct lsmblob *blob, u32 field,
+					u32 op, void *lsmrule)
 {
 	return -EINVAL;
 }
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index cd393aaa17d5..3e47cc9b7400 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -562,6 +562,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 	for (i = 0; i < MAX_LSM_RULES; i++) {
 		int rc = 0;
 		u32 osid;
+		struct lsmblob lsmdata;
 
 		if (!ima_lsm_isset(rule->lsm[i].rules)) {
 			if (!rule->lsm[i].args_p)
@@ -574,14 +575,16 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 		case LSM_OBJ_ROLE:
 		case LSM_OBJ_TYPE:
 			security_inode_getsecid(inode, &osid);
-			rc = ima_filter_rule_match(osid, rule->lsm[i].type,
+			lsmblob_init(&lsmdata, osid);
+			rc = ima_filter_rule_match(&lsmdata, rule->lsm[i].type,
 						   Audit_equal,
 						   rule->lsm[i].rules);
 			break;
 		case LSM_SUBJ_USER:
 		case LSM_SUBJ_ROLE:
 		case LSM_SUBJ_TYPE:
-			rc = ima_filter_rule_match(secid, rule->lsm[i].type,
+			lsmblob_init(&lsmdata, secid);
+			rc = ima_filter_rule_match(&lsmdata, rule->lsm[i].type,
 						   Audit_equal,
 						   rule->lsm[i].rules);
 		default:
diff --git a/security/security.c b/security/security.c
index d01363cb0082..4ecbef074809 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2558,11 +2558,14 @@ void security_audit_rule_free(void **lsmrule)
 	hlist_for_each_entry(hp, &security_hook_heads.audit_rule_free, list) {
 		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
 			continue;
+		if (lsmrule[hp->lsmid->slot] == NULL)
+			continue;
 		hp->hook.audit_rule_free(lsmrule[hp->lsmid->slot]);
 	}
 }
 
-int security_audit_rule_match(u32 secid, u32 field, u32 op, void **lsmrule)
+int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
+			      void **lsmrule)
 {
 	struct security_hook_list *hp;
 	int rc;
@@ -2570,7 +2573,10 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op, void **lsmrule)
 	hlist_for_each_entry(hp, &security_hook_heads.audit_rule_match, list) {
 		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
 			continue;
-		rc = hp->hook.audit_rule_match(secid, field, op,
+		if (lsmrule[hp->lsmid->slot] == NULL)
+			continue;
+		rc = hp->hook.audit_rule_match(blob->secid[hp->lsmid->slot],
+					       field, op,
 					       &lsmrule[hp->lsmid->slot]);
 		if (rc)
 			return rc;
-- 
2.24.1

