[PATCH v15 09/26] ima: Move ima_lsm_policy_notifier into ima_namespace

From: Stefan Berger <stefanb@linux.ibm.com>
Date: 2023-02-06 14:04:31
Also in: linux-integrity, lkml
Subsystem: extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers: Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds

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@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>

---

v15:
 - Pass ima_namespace into ima_match_rules() to pass to ima_lsm_copy_rule()

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      | 34 ++++++++++++++++--------
 4 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 75993ad061fa..db28d6d222a6 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 e3a3a54dc79e..c7a5f47b50fc 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();

@@ -1096,7 +1092,7 @@ 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 502b1e8021a6..8e71b28855a4 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c

@@ -392,7 +392,8 @@ 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;

@@ -417,19 +418,26 @@ 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)
 {
 	int i;
 	struct ima_rule_entry *nentry;
 
-	nentry = ima_lsm_copy_rule(entry);
+	nentry = ima_lsm_copy_rule(ns, entry);
 	if (!nentry)
 		return -ENOMEM;

@@ -473,7 +481,7 @@ 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;

@@ -484,12 +492,14 @@ 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;
 }

@@ -544,6 +554,7 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
 
 /**
  * ima_match_rules - determine whether an inode matches the policy rule.
+ * @ns: IMA namespace that has the policy
  * @rule: a pointer to a rule
  * @mnt_userns:	user namespace of the mount the inode was found from
  * @inode: a pointer to an inode

@@ -555,7 +566,8 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
  *
  * Returns true on rule match, false on failure.
  */
-static bool ima_match_rules(struct ima_rule_entry *rule,
+static bool ima_match_rules(struct ima_namespace *ns,
+			    struct ima_rule_entry *rule,
 			    struct user_namespace *mnt_userns,
 			    struct inode *inode, const struct cred *cred,
 			    u32 secid, enum ima_hooks func, int mask,

@@ -657,7 +669,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
 		}
 
 		if (rc == -ESTALE && !rule_reinitialized) {
-			lsm_rule = ima_lsm_copy_rule(rule);
+			lsm_rule = ima_lsm_copy_rule(ns, rule);
 			if (lsm_rule) {
 				rule_reinitialized = true;
 				goto retry;

@@ -747,7 +759,7 @@ int ima_match_policy(struct ima_namespace *ns,
 		if (!(entry->action & actmask))
 			continue;
 
-		if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
+		if (!ima_match_rules(ns, entry, mnt_userns, inode, cred, secid,
 				     func, mask, func_data))
 			continue;

-- 
2.37.3

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