[PATCH v12 03/25] LSM: Use lsmblob in security_audit_rule_match
Stephen Smalley
sds at tycho.nsa.gov
Wed Dec 18 13:16:31 UTC 2019
On 12/17/19 7:28 PM, Casey Schaufler wrote:
> 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?
No, I already acked it in my reply, just thought I'd ask about the WARN_ON.
>
>
>>
>>>
>>>> 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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