Re: [PATCH ghak81 RFC V1 2/5] audit: convert sessionid unset to a macro

[Paul Moore]

On Tue, May 8, 2018 at 9:34 PM, Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> On 2018-05-04 16:54, Richard Guy Briggs wrote:
>> Use a macro, "AUDIT_SID_UNSET", to replace each instance of
>> initialization and comparison to an audit session ID.
>>
>> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
>
> There's a minor issue with this patch, adding a header include to
> init/init_task.c in this patch and removing it from patch 5.  That'll be
> in the next revision.

Okay, thanks for the heads-up.  FWIW, this patch looks reasonable in
principle; changing magic numbers to macros/constants is almost always
a step in the right direction.

> I have dynamic allocation working, so that has a good chance of
> appearing  too.

I'll comment on that in your patch 0, I just want to get through the
rest of the patches first.

>> ---
>>  include/linux/audit.h      | 2 +-
>>  include/net/xfrm.h         | 2 +-
>>  include/uapi/linux/audit.h | 1 +
>>  init/init_task.c           | 2 +-
>>  kernel/auditsc.c           | 4 ++--
>>  5 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/linux/audit.h b/include/linux/audit.h
>> index 75d5b03..5f86f7c 100644
>> --- a/include/linux/audit.h
>> +++ b/include/linux/audit.h
>> @@ -513,7 +513,7 @@ static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
>>  }
>>  static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
>>  {
>> -     return -1;
>> +     return AUDIT_SID_UNSET;
>>  }
>>  static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
>>  { }
>> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
>> index a872379..fcce8ee 100644
>> --- a/include/net/xfrm.h
>> +++ b/include/net/xfrm.h
>> @@ -751,7 +751,7 @@ static inline void xfrm_audit_helper_usrinfo(bool task_valid,
>>                                           audit_get_loginuid(current) :
>>                                           INVALID_UID);
>>       const unsigned int ses = task_valid ? audit_get_sessionid(current) :
>> -             (unsigned int) -1;
>> +             AUDIT_SID_UNSET;
>>
>>       audit_log_format(audit_buf, " auid=%u ses=%u", auid, ses);
>>       audit_log_task_context(audit_buf);
>> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
>> index 4e61a9e..04f9bd2 100644
>> --- a/include/uapi/linux/audit.h
>> +++ b/include/uapi/linux/audit.h
>> @@ -465,6 +465,7 @@ struct audit_tty_status {
>>  };
>>
>>  #define AUDIT_UID_UNSET (unsigned int)-1
>> +#define AUDIT_SID_UNSET ((unsigned int)-1)
>>
>>  /* audit_rule_data supports filter rules with both integer and string
>>   * fields.  It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and
>> diff --git a/init/init_task.c b/init/init_task.c
>> index 3ac6e75..c788f91 100644
>> --- a/init/init_task.c
>> +++ b/init/init_task.c
>> @@ -119,7 +119,7 @@ struct task_struct init_task
>>       .thread_node    = LIST_HEAD_INIT(init_signals.thread_head),
>>  #ifdef CONFIG_AUDITSYSCALL
>>       .loginuid       = INVALID_UID,
>> -     .sessionid      = (unsigned int)-1,
>> +     .sessionid      = AUDIT_SID_UNSET,
>>  #endif
>>  #ifdef CONFIG_PERF_EVENTS
>>       .perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex),
>> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
>> index f3817d0..6e3ceb9 100644
>> --- a/kernel/auditsc.c
>> +++ b/kernel/auditsc.c
>> @@ -2050,7 +2050,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
>>  int audit_set_loginuid(kuid_t loginuid)
>>  {
>>       struct task_struct *task = current;
>> -     unsigned int oldsessionid, sessionid = (unsigned int)-1;
>> +     unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
>>       kuid_t oldloginuid;
>>       int rc;
>>
>> @@ -2064,7 +2064,7 @@ int audit_set_loginuid(kuid_t loginuid)
>>       /* are we setting or clearing? */
>>       if (uid_valid(loginuid)) {
>>               sessionid = (unsigned int)atomic_inc_return(&session_id);
>> -             if (unlikely(sessionid == (unsigned int)-1))
>> +             if (unlikely(sessionid == AUDIT_SID_UNSET))
>>                       sessionid = (unsigned int)atomic_inc_return(&session_id);
>>       }
>>
>> --
>> 1.8.3.1
>>
>> --
>> Linux-audit mailing list
>> Linux-audit@xxxxxxxxxx
>> https://www.redhat.com/mailman/listinfo/linux-audit
>
> - RGB
>
> --
> Richard Guy Briggs <rgb@xxxxxxxxxx>
> Sr. S/W Engineer, Kernel Security, Base Operating Systems
> Remote, Ottawa, Red Hat Canada
> IRC: rgb, SunRaycer
> Voice: +1.647.777.2635, Internal: (81) 32635
>
> --
> Linux-audit mailing list
> Linux-audit@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/linux-audit



-- 
paul moore
www.paul-moore.com