Re: [PATCH v4 05/23] LSM: Use lsmblob in security_audit_rule_match

[John Johansen <john.johansen@canonical.com>]

On 6/26/19 12:22 PM, Casey Schaufler wrote:
> 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.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

Reviewed-by: John Johansen <john.johansen@canonical.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(-)
> 
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 5bb8b9a6fa84..4f8b478bc3a1 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1761,7 +1761,8 @@ 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
> @@ -1777,8 +1778,8 @@ 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 63f8b3f26fab..8786b95b60bd 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -1324,6 +1324,7 @@ 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:
> @@ -1354,8 +1355,10 @@ 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 d1eab1d4a930..18ee5556c086 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);
> @@ -630,7 +631,9 @@ 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);
>  			}
> @@ -645,15 +648,17 @@ 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)) {
> @@ -665,7 +670,8 @@ 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 d213e835c498..5a337239d9e4 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -307,8 +307,8 @@ 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 e0cc323f948f..e7b8ce942950 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -327,6 +327,7 @@ 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;
>  		int retried = 0;
>  
>  		if (!rule->lsm[i].rule)
> @@ -337,7 +338,8 @@ 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);
> @@ -345,7 +347,8 @@ 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 27e2db3d6b04..46ca4b85ad96 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -424,7 +424,7 @@ 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;
>  
>  /**
>   * security_add_hooks - Add a modules hooks to the hook lists.
> @@ -2433,9 +2433,21 @@ 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 */
>  
>