Re: [PATCH 8/8] ima: Differentiate auditing policy rules from "audit" actions

Stefan Berger
2018-05-30T21:38:27Z

On 05/30/2018 05:22 PM, Paul Moore wrote:
> On Wed, May 30, 2018 at 9:08 AM, Stefan Berger
> <stefanb@linux.vnet.ibm.com> wrote:
>> On 05/30/2018 08:49 AM, Richard Guy Briggs wrote:
>>> On 2018-05-24 16:11, Stefan Berger wrote:
>>>> The AUDIT_INTEGRITY_RULE is used for auditing IMA policy rules and
>>>> the IMA "audit" policy action. This patch defines
>>>> AUDIT_INTEGRITY_POLICY_RULE to reflect the IMA policy rules.
>>>>
>>>> With this change we now call integrity_audit_msg_common() to get
>>>> common integrity auditing fields. This now produces the following
>>>> record when parsing an IMA policy rule:
>>>>
>>>> type=UNKNOWN[1806] msg=audit(1527004216.690:311): action=dont_measure \
>>>> fsmagic=0x9fa0 pid=1613 uid=0 auid=0 ses=2 \
>>>> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 \
>>>> op=policy_update cause=parse_rule comm="echo" exe="/usr/bin/echo" \
>>>> tty=tty2 res=1
>>>>
>>>> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
>>>> ---
>>>> include/uapi/linux/audit.h | 3 ++-
>>>> security/integrity/ima/ima_policy.c | 5 +++--
>>>> 2 files changed, 5 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
>>>> index 4e61a9e05132..776e0abd35cf 100644
>>>> --- a/include/uapi/linux/audit.h
>>>> +++ b/include/uapi/linux/audit.h
>>>> @@ -146,7 +146,8 @@
>>>> #define AUDIT_INTEGRITY_STATUS 1802 /* Integrity enable
>>>> status */
>>>> #define AUDIT_INTEGRITY_HASH 1803 /* Integrity HASH type */
>>>> #define AUDIT_INTEGRITY_PCR 1804 /* PCR invalidation msgs */
>>>> -#define AUDIT_INTEGRITY_RULE 1805 /* policy rule */
>>>> +#define AUDIT_INTEGRITY_RULE 1805 /* IMA "audit" action policy
>>>> msgs */
>>>> +#define AUDIT_INTEGRITY_POLICY_RULE 1806 /* IMA policy rules */
>>>> #define AUDIT_KERNEL 2000 /* Asynchronous audit
>>>> record. NOT A REQUEST. */
>>>> diff --git a/security/integrity/ima/ima_policy.c
>>>> b/security/integrity/ima/ima_policy.c
>>>> index 3aed25a7178a..a8ae47a386b4 100644
>>>> --- a/security/integrity/ima/ima_policy.c
>>>> +++ b/security/integrity/ima/ima_policy.c
>>>> @@ -634,7 +634,7 @@ static int ima_parse_rule(char *rule, struct
>>>> ima_rule_entry *entry)
>>>> int result = 0;
>>>> ab = integrity_audit_log_start(NULL, GFP_KERNEL,
>>>> - AUDIT_INTEGRITY_RULE);
>>>> + AUDIT_INTEGRITY_POLICY_RULE);
>>> Is it possible to connect this record to a syscall by replacing the
>>> first parameter (NULL) by current->context?
> We're likely going to need to "associate" this record (audit speak for
> making the first parameter non-NULL) with others for the audit
> container ID work. If you do it now, Richard's patches will likely
> get a few lines smaller and that will surely make him a bit happier :)

Richard is also introducing a local context that we can then create and
use instead of the NULL. Can we not use that then?

Steven seems to say: "We don't want to add syscall records to
everything. That messes up schemas and existing code. The integrity
events are 1 record in size and should stay that way. This saves disk
space and improves readability."

>
>> We would have to fix current->context in this case since it is NULL. We get
>> to this location by root cat'ing a policy or writing a policy filename into
>> /sys/kernel/security/ima/policy.
> Perhaps I'm missing something, but current in this case should point
> to the process which is writing to the policy file, yes?
>
Yes, but current->context is NULL for some reason.