[PATCH v12 03/25] LSM: Use lsmblob in security_audit_rule_match
Casey Schaufler
casey at schaufler-ca.com
Wed Dec 18 00:28:38 UTC 2019
On 12/17/2019 3:47 PM, Kees Cook wrote:
> On Tue, Dec 17, 2019 at 02:01:19PM -0800, Casey Schaufler wrote:
>> On 12/17/2019 9:34 AM, Stephen Smalley wrote:
>>> On 12/16/19 5:35 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.
>>>>
>>>> Reviewed-by: Kees Cook <keescook at chromium.org>
>>>> Reviewed-by: John Johansen <john.johansen at canonical.com>
>>>> Signed-off-by: Casey Schaufler <casey at 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(-)
>>>>
>>>> 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;
>>> Do you think we really need to retain these WARN_ON()s?
>> Kees was especially keen on having the WARN_ON().
>> I'd be fine with removing it.
> It should really really never happen, so I like the WARN_ON staying.
>
> -Kees
Given that Mr. Hardening likes it the way it is, I'm inclined to leave
it as is. Would that prevent an Ack?
>
>>
>>> If not, then you could dispense with it now and leave lsm_slot as __initdata? Otherwise,
>>> Acked-by: Stephen Smalley <sds at tycho.nsa.gov>
>>>
>>>> + rc = hp->hook.audit_rule_match(blob->secid[hp->lsmid->slot],
>>>> + field, op, lsmrule);
>>>> + if (rc != 0)
>>>> + return rc;
>>>> + }
>>>> + return 0;
>>>> }
>>>> #endif /* CONFIG_AUDIT */
>>>>
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