Re: [PATCH v3 0/4] Better integrate seccomp logging and auditing

[Paul Moore]

On Sun, May 6, 2018 at 7:36 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> On Sun, May 6, 2018 at 2:31 PM, Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
>> On Thu, May 3, 2018 at 9:08 PM, Tyler Hicks <tyhicks@xxxxxxxxxxxxx> wrote:
>>> Seccomp received improved logging controls in v4.14. Applications can opt into
>>> logging of "handled" actions (SECCOMP_RET_TRAP, SECCOMP_RET_TRACE,
>>> SECCOMP_RET_ERRNO) using the SECCOMP_FILTER_FLAG_LOG bit when loading filters.
>>> They can also debug filter matching with the new SECCOMP_RET_LOG action.
>>> Administrators can prevent specific actions from being logged using the
>>> kernel.seccomp.actions_logged sysctl.
>>>
>>> However, one corner case intentionally wasn't addressed in those v4.14 changes.
>>> When a process is being inspected by the audit subsystem, seccomp's decision
>>> making for logging ignores the new controls and unconditionally logs every
>>> action taken except for SECCOMP_RET_ALLOW. This isn't particularly useful since
>>> many existing applications don't intend to log handled actions due to them
>>> occurring very frequently. This amount of logging fills the audit logs without
>>> providing many benefits now that application authors have fine grained controls
>>> at their disposal.
>>>
>>> This patch set aligns the seccomp logging behavior for both audited and
>>> non-audited processes. It also emits an audit record, if auditing is enabled,
>>> when the kernel.seccomp.actions_logged sysctl is written to so that there's a
>>> paper trail when entire actions are quieted.
>>>
>>> Changes in v3:
>>> * Patch 3
>>>   - Never drop a field when emitting the audit record
>>>   - Use the value "?" for the actions field when an error occurred while
>>>     writing to the sysctl
>>>   - Use the value "?" for the actions and/or old-actions fields when a failure
>>>     to translate actions to names
>>>   - Use the value "(none)" for the actions and/or old-actions fields when no
>>>     actions are specified
>>>     + This is possible when writing an empty string to the sysctl
>>>   - Update the commit message to note the new values and give an example of
>>>     when an empty string is written
>>> * Patch 4
>>>   - Adjust the control flow of seccomp_log() to exit early if nothing should be
>>>     logged
>>>
>>> Changes in v2:
>>> * Patch 2
>>>   - New patch, allowing for a configurable separator between action names
>>> * Patch 3
>>>   - The value of the actions field in the audit record now uses a comma instead
>>>     of a space
>>>   - The value of the actions field in the audit record is no longer enclosed in
>>>     quotes
>>>   - audit_log_start() is called with the current processes' audit_context in
>>>     audit_seccomp_actions_logged()
>>>   - audit_seccomp_actions_logged() no longer records the pid, uid, auid, tty,
>>>     ses, task context, comm, or executable path
>>>   - The new and old value of seccomp_actions_logged is recorded in the
>>>     AUDIT_CONFIG_CHANGE record
>>>   - The value of the "res" field in the CONFIG_CHANGE audit record is corrected
>>>     (1 indicates success, 0 failure)
>>>   - Updated patch 3's commit message to reflect the updated audit record format
>>>     in the examples
>>> * Patch 4
>>>   - A function comment for audit_seccomp() was added to explain, among other
>>>     things, that event filtering is performed in seccomp_log()
>>
>> Kees, are you still okay with v3?  Also, are you okay with these
>> patches going in via the audit tree, or would you prefer to take them
>> via seccomp?  I've got a slight preference for the audit tree myself,
>> but as I said before, as long as it hits Linus' tree I'm happy.
>
> Yup, it looks good. I have no tree preference, so you win! :) Please
> consider the whole series:
>
> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

Merged into audit/next, thanks guys.

-- 
paul moore
www.paul-moore.com