[PATCH v11 10/27] ima: Move ima_lsm_policy_notifier into ima_namespace

[Stefan Berger]

Move the ima_lsm_policy_notifier into the ima_namespace. Each IMA
namespace can now register its own LSM policy change notifier callback.
The policy change notifier for the init_ima_ns still remains in init_ima()
and therefore handle the registration of the callback for all other
namespaces in init_ima_namespace().

Rate-limit the kernel warning 'rule for LSM <label> is undefined` for
IMA namespace to avoid flooding the kernel log with this type of message.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>

---
v11:
 - Renamed 'rc' to 'ret'
 - Use pr_warn_ratelimited('rule for LSM...') for IMA namespaces

v10:
 - Only call pr_warn('rule for LSM <label> is undefined`) for init_ima_ns
---
 security/integrity/ima/ima.h             |  2 ++
 security/integrity/ima/ima_init_ima_ns.c | 14 +++++++++++++
 security/integrity/ima/ima_main.c        |  6 +-----
 security/integrity/ima/ima_policy.c      | 26 ++++++++++++++++--------
 4 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b35c8504ef87..c68b5117d034 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -144,6 +144,8 @@ struct ima_namespace {
 	int valid_policy;
 
 	struct dentry *ima_policy;
+
+	struct notifier_block ima_lsm_policy_notifier;
 } __randomize_layout;
 extern struct ima_namespace init_ima_ns;
 
diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
index 425eed1c6838..c4fe8f3e9a73 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -10,6 +10,8 @@
 
 static int ima_init_namespace(struct ima_namespace *ns)
 {
+	int ret;
+
 	INIT_LIST_HEAD(&ns->ima_default_rules);
 	INIT_LIST_HEAD(&ns->ima_policy_rules);
 	INIT_LIST_HEAD(&ns->ima_temp_rules);
@@ -30,6 +32,15 @@ static int ima_init_namespace(struct ima_namespace *ns)
 	ns->valid_policy = 1;
 	ns->ima_fs_flags = 0;
 
+	if (ns != &init_ima_ns) {
+		ns->ima_lsm_policy_notifier.notifier_call =
+						ima_lsm_policy_change;
+		ret = register_blocking_lsm_notifier
+						(&ns->ima_lsm_policy_notifier);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 
@@ -39,5 +50,8 @@ int __init ima_ns_init(void)
 }
 
 struct ima_namespace init_ima_ns = {
+	.ima_lsm_policy_notifier = {
+		.notifier_call = ima_lsm_policy_change,
+	},
 };
 EXPORT_SYMBOL(init_ima_ns);
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index c654c28fda14..b95cc0c427d5 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -38,10 +38,6 @@ int ima_appraise;
 int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
 static int hash_setup_done;
 
-static struct notifier_block ima_lsm_policy_notifier = {
-	.notifier_call = ima_lsm_policy_change,
-};
-
 static int __init hash_setup(char *str)
 {
 	struct ima_template_desc *template_desc = ima_template_desc_current();
@@ -1072,7 +1068,7 @@ static int __init init_ima(void)
 	if (error)
 		return error;
 
-	error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
+	error = register_blocking_lsm_notifier(&ns->ima_lsm_policy_notifier);
 	if (error)
 		pr_warn("Couldn't register LSM notifier, error %d\n", error);
 
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 05b2bc06ab0c..94a41572527a 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -369,7 +369,8 @@ static void ima_free_rule(struct ima_rule_entry *entry)
 	kfree(entry);
 }
 
-static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
+static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_namespace *ns,
+						struct ima_rule_entry *entry)
 {
 	struct ima_rule_entry *nentry;
 	int i;
@@ -400,18 +401,25 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 		ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
 				     nentry->lsm[i].args_p,
 				     &nentry->lsm[i].rule);
-		if (!nentry->lsm[i].rule)
-			pr_warn("rule for LSM \'%s\' is undefined\n",
-				nentry->lsm[i].args_p);
+		if (!nentry->lsm[i].rule) {
+			if (ns == &init_ima_ns)
+				pr_warn("rule for LSM \'%s\' is undefined\n",
+					nentry->lsm[i].args_p);
+			else
+				pr_warn_ratelimited
+					("rule for LSM \'%s\' is undefined\n",
+					 nentry->lsm[i].args_p);
+		}
 	}
 	return nentry;
 }
 
-static int ima_lsm_update_rule(struct ima_rule_entry *entry)
+static int ima_lsm_update_rule(struct ima_namespace *ns,
+			       struct ima_rule_entry *entry)
 {
 	struct ima_rule_entry *nentry;
 
-	nentry = ima_lsm_copy_rule(entry);
+	nentry = ima_lsm_copy_rule(ns, entry);
 	if (!nentry)
 		return -ENOMEM;
 
@@ -454,7 +462,7 @@ static void ima_lsm_update_rules(struct ima_namespace *ns)
 		if (!ima_rule_contains_lsm_cond(entry))
 			continue;
 
-		result = ima_lsm_update_rule(entry);
+		result = ima_lsm_update_rule(ns, entry);
 		if (result) {
 			pr_err("lsm rule update error %d\n", result);
 			return;
@@ -465,12 +473,14 @@ static void ima_lsm_update_rules(struct ima_namespace *ns)
 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
 			  void *lsm_data)
 {
-	struct ima_namespace *ns = &init_ima_ns;
+	struct ima_namespace *ns;
 
 	if (event != LSM_POLICY_CHANGE)
 		return NOTIFY_DONE;
 
+	ns = container_of(nb, struct ima_namespace, ima_lsm_policy_notifier);
 	ima_lsm_update_rules(ns);
+
 	return NOTIFY_OK;
 }
 
-- 
2.31.1