linux-kernel - [PATCH v3 01/12] ima: Have the LSM free its audit rule

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Date:   Thu,  9 Jul 2020 01:19:00 -0500
From:   Tyler Hicks <tyhicks@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc:     James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Prakhar Srivastava <prsriva02@...il.com>,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Janne Karhunen <janne.karhunen@...il.com>,
        Casey Schaufler <casey@...aufler-ca.com>
Subject: [PATCH v3 01/12] ima: Have the LSM free its audit rule

Ask the LSM to free its audit rule rather than directly calling kfree().
Both AppArmor and SELinux do additional work in their audit_rule_free()
hooks. Fix memory leaks by allowing the LSMs to perform necessary work.

Fixes: b16942455193 ("ima: use the lsm policy update notifier")
Signed-off-by: Tyler Hicks <tyhicks@...ux.microsoft.com>
Cc: Janne Karhunen <janne.karhunen@...il.com>
Cc: Casey Schaufler <casey@...aufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
---

* v3
  - No change
* v2
  - Fixed build warning by dropping the 'return -EINVAL' from
    the stubbed out security_filter_rule_free() since it has a void
    return type
  - Added Mimi's Reviewed-by
  - Developed a follow-on patch to rename security_filter_rule_*()
    functions, to address Casey's request, but I'll submit it
    independently of this patch series since it is somewhat unrelated

 security/integrity/ima/ima.h        | 5 +++++
 security/integrity/ima/ima_policy.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 4515975cc540..59ec28f5c117 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -420,6 +420,7 @@ static inline void ima_free_modsig(struct modsig *modsig)
 #ifdef CONFIG_IMA_LSM_RULES
 
 #define security_filter_rule_init security_audit_rule_init
+#define security_filter_rule_free security_audit_rule_free
 #define security_filter_rule_match security_audit_rule_match
 
 #else
@@ -430,6 +431,10 @@ static inline int security_filter_rule_init(u32 field, u32 op, char *rulestr,
 	return -EINVAL;
 }
 
+static inline void security_filter_rule_free(void *lsmrule)
+{
+}
+
 static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
 					     void *lsmrule)
 {
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 66aa3e17a888..d7c268c2b0ce 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -258,7 +258,7 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry)
 	int i;
 
 	for (i = 0; i < MAX_LSM_RULES; i++) {
-		kfree(entry->lsm[i].rule);
+		security_filter_rule_free(entry->lsm[i].rule);
 		kfree(entry->lsm[i].args_p);
 	}
 	kfree(entry);
-- 
2.25.1