diff mbox series

[v12,03/25] LSM: Use lsmblob in security_audit_rule_match

Message ID 20191224231915.7208-4-casey@schaufler-ca.com (mailing list archive)
State Superseded
Headers show
Series [v12,01/25] LSM: Infrastructure management of the sock security | expand

Commit Message

Casey Schaufler Dec. 24, 2019, 11:18 p.m. UTC 
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. In some cases this requires a
temporary conversion using lsmblob_init() that will go
away when other interfaces get converted.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/security.h            |  7 ++++---
 kernel/auditfilter.c                |  7 +++++--
 kernel/auditsc.c                    | 14 ++++++++++----
 security/integrity/ima/ima.h        |  4 ++--
 security/integrity/ima/ima_policy.c |  7 +++++--
 security/security.c                 | 18 +++++++++++++++---
 6 files changed, 41 insertions(+), 16 deletions(-)

Comments

Mimi Zohar Dec. 31, 2019, 5:14 p.m. UTC | #1 
[Cc'ing Matthew Garret based on the additional bprm call to
process_measurement() - commit d906c10d8a31 ("IMA: Support using new
creds in appraisal policy")]

On Tue, 2019-12-24 at 15:18 -0800, Casey Schaufler wrote:
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index f19a895ad7cd..193ddd55420b 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -414,6 +414,7 @@ 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 blob;
> 
>  		if (!rule->lsm[i].rule)
>  			continue;
> @@ -423,7 +424,8 @@ 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 = security_filter_rule_match(osid,
> +			lsmblob_init(&blob, osid);
> +			rc = security_filter_rule_match(&blob,
>  							rule->lsm[i].type,
>  							Audit_equal,
>  							rule->lsm[i].rule);
> @@ -431,7 +433,8 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>  		case LSM_SUBJ_USER:
>  		case LSM_SUBJ_ROLE:
>  		case LSM_SUBJ_TYPE:
> -			rc = security_filter_rule_match(secid,
> +			lsmblob_init(&blob, secid);
> +			rc = security_filter_rule_match(&blob,

On the bprm hook, IMA calls process_measurement() twice.  The first
time the secid is passed as an argument based on a call to
security_task_getsecid(), while the second time it is based on
security_cred_getsecid().  process_measurement() passes the correct
secid converted to a blob, but instead of using the passed variable,
this code uses the locally defined blob field.  A later patch removes
the the lsmblob_init(), leaving the local blob uninitialized.
 Something is terribly wrong here.

Mimi

>  							rule->lsm[i].type,
>  							Audit_equal,
>  							rule->lsm[i].rule);



>
Casey Schaufler Dec. 31, 2019, 5:36 p.m. UTC | #2 
On 12/31/2019 9:14 AM, Mimi Zohar wrote:
> [Cc'ing Matthew Garret based on the additional bprm call to
> process_measurement() - commit d906c10d8a31 ("IMA: Support using new
> creds in appraisal policy")]
>
> On Tue, 2019-12-24 at 15:18 -0800, Casey Schaufler wrote:
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index f19a895ad7cd..193ddd55420b 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -414,6 +414,7 @@ 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 blob;
>>
>>  		if (!rule->lsm[i].rule)
>>  			continue;
>> @@ -423,7 +424,8 @@ 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 = security_filter_rule_match(osid,
>> +			lsmblob_init(&blob, osid);
>> +			rc = security_filter_rule_match(&blob,
>>  							rule->lsm[i].type,
>>  							Audit_equal,
>>  							rule->lsm[i].rule);
>> @@ -431,7 +433,8 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>>  		case LSM_SUBJ_USER:
>>  		case LSM_SUBJ_ROLE:
>>  		case LSM_SUBJ_TYPE:
>> -			rc = security_filter_rule_match(secid,
>> +			lsmblob_init(&blob, secid);
>> +			rc = security_filter_rule_match(&blob,
> On the bprm hook, IMA calls process_measurement() twice.  The first
> time the secid is passed as an argument based on a call to
> security_task_getsecid(), while the second time it is based on
> security_cred_getsecid().  process_measurement() passes the correct
> secid converted to a blob, but instead of using the passed variable,
> this code uses the locally defined blob field.  A later patch removes
> the the lsmblob_init(), leaving the local blob uninitialized.
>  Something is terribly wrong here.

I can see that there's significant work required on audit rule
filtering. security_audit_rule_init() isn't going to work correctly
the way it is. 

I'll admit that the aliasing of audit_rule to filter_rule had me
very confused for some time.

>
> Mimi
>
>>  							rule->lsm[i].type,
>>  							Audit_equal,
>>  							rule->lsm[i].rule);
>
>
diff mbox series

Patch

diff --git a/include/linux/security.h b/include/linux/security.h
index b74dc70088ca..9c6dbe248eaf 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1837,7 +1837,8 @@  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
@@ -1853,8 +1854,8 @@  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 b0126e9c0743..356db1dd276c 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1325,6 +1325,7 @@  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:
@@ -1355,8 +1356,10 @@  int audit_filter(int msgtype, unsigned int listtype)
 			case AUDIT_SUBJ_CLR:
 				if (f->lsm_rule) {
 					security_task_getsecid(current, &sid);
-					result = security_audit_rule_match(sid,
-						   f->type, f->op, f->lsm_rule);
+					lsmblob_init(&blob, sid);
+					result = security_audit_rule_match(
+							&blob, f->type,
+							f->op, f->lsm_rule);
 				}
 				break;
 			case AUDIT_EXE:
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4effe01ebbe2..7566e5b1c419 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -445,6 +445,7 @@  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);
@@ -643,7 +644,9 @@  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_rule);
 			}
@@ -658,15 +661,17 @@  static int audit_filter_rules(struct task_struct *tsk,
 			if (f->lsm_rule) {
 				/* 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_rule);
 				} else if (ctx) {
 					list_for_each_entry(n, &ctx->names_list, list) {
+						lsmblob_init(&blob, n->osid);
 						if (security_audit_rule_match(
-								n->osid,
+								&blob,
 								f->type,
 								f->op,
 								f->lsm_rule)) {
@@ -678,7 +683,8 @@  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_rule))
 					++result;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index df4ca482fb53..d95b0ece7434 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -381,8 +381,8 @@  static inline int security_filter_rule_init(u32 field, u32 op, char *rulestr,
 	return -EINVAL;
 }
 
-static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
-					     void *lsmrule)
+static inline int security_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 f19a895ad7cd..193ddd55420b 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -414,6 +414,7 @@  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 blob;
 
 		if (!rule->lsm[i].rule)
 			continue;
@@ -423,7 +424,8 @@  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 = security_filter_rule_match(osid,
+			lsmblob_init(&blob, osid);
+			rc = security_filter_rule_match(&blob,
 							rule->lsm[i].type,
 							Audit_equal,
 							rule->lsm[i].rule);
@@ -431,7 +433,8 @@  static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 		case LSM_SUBJ_USER:
 		case LSM_SUBJ_ROLE:
 		case LSM_SUBJ_TYPE:
-			rc = security_filter_rule_match(secid,
+			lsmblob_init(&blob, secid);
+			rc = security_filter_rule_match(&blob,
 							rule->lsm[i].type,
 							Audit_equal,
 							rule->lsm[i].rule);
diff --git a/security/security.c b/security/security.c
index a89634af639a..bfea9739c084 100644
--- a/security/security.c
+++ b/security/security.c
@@ -439,7 +439,7 @@  static int lsm_append(const char *new, char **result)
 /*
  * Current index to use while initializing the lsmblob secid list.
  */
-static int lsm_slot __initdata;
+static int lsm_slot __lsm_ro_after_init;
 
 /**
  * security_add_hooks - Add a modules hooks to the hook lists.
@@ -2412,9 +2412,21 @@  void security_audit_rule_free(void *lsmrule)
 	call_void_hook(audit_rule_free, lsmrule);
 }
 
-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)
 {
-	return call_int_hook(audit_rule_match, 0, secid, field, op, lsmrule);
+	struct security_hook_list *hp;
+	int rc;
+
+	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(blob->secid[hp->lsmid->slot],
+					       field, op, lsmrule);
+		if (rc != 0)
+			return rc;
+	}
+	return 0;
 }
 #endif /* CONFIG_AUDIT */