On 02/16/2017 12:40 PM, Tyler Hicks wrote:
> On 02/15/2017 07:10 PM, Kees Cook wrote:
>> On Mon, Feb 13, 2017 at 7:55 PM, Tyler Hicks <tyhicks@xxxxxxxxxxxxx> wrote:
>>> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
>>> index e36dfe9..270a227 100644
>>> --- a/kernel/seccomp.c
>>> +++ b/kernel/seccomp.c
>>> @@ -509,6 +509,22 @@ static void seccomp_send_sigsys(int syscall, int reason)
>>> }
>>> #endif /* CONFIG_SECCOMP_FILTER */
>>>
>>> +static u32 seccomp_log_max_action = SECCOMP_RET_KILL;
>>> +
>>> +static inline void seccomp_log(unsigned long syscall, long signr, u32 action)
>>> +{
>>> + /* Force an audit message to be emitted when the action is not greater
>>> + * than the configured maximum action.
>>> + */
>>> + if (action <= seccomp_log_max_action)
>>> + return __audit_seccomp(syscall, signr, action);
>>> +
>>> + /* Let the audit subsystem decide if the action should be audited based
>>> + * on whether the current task itself is being audited.
>>> + */
>>
>> Nitpick on comment style, please use:
>>
>> /*
>> * line 1
>> * line 2...
>> */
>
> No problem.
>
>>
>>> + return audit_seccomp(syscall, signr, action);
>>> +}
>>> +
>>> /*
>>> * Secure computing mode 1 allows only read/write/exit/sigreturn.
>>> * To be fully secure this must be combined with rlimit
>>> @@ -534,7 +550,7 @@ static void __secure_computing_strict(int this_syscall)
>>> #ifdef SECCOMP_DEBUG
>>> dump_stack();
>>> #endif
>>> - audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL);
>>> + seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL);
>>> do_exit(SIGKILL);
>>> }
>>>
>>> @@ -633,18 +649,30 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
>>> return 0;
>>>
>>> case SECCOMP_RET_ALLOW:
>>> + /* Open-coded seccomp_log(), optimized for the RET_ALLOW hot
>>> + * path.
>>> + *
>>> + * We only want to log RET_ALLOW actions when the admin has
>>> + * configured them to be logged via the log_max_action sysctl.
>>> + * Therefore, call __audit_seccomp() directly so that RET_ALLOW
>>> + * actions are not audited simply because the task is being
>>> + * audited.
>>> + */
>>> + if (unlikely(seccomp_log_max_action == SECCOMP_RET_ALLOW))
>>> + __audit_seccomp(this_syscall, 0, action);
>>> +
>>> return 0;
>>>
>>> case SECCOMP_RET_KILL:
>>> default:
>>> - audit_seccomp(this_syscall, SIGSYS, action);
>>> + seccomp_log(this_syscall, SIGSYS, action);
>>> do_exit(SIGSYS);
>>> }
>>>
>>> unreachable();
>>>
>>> skip:
>>> - audit_seccomp(this_syscall, 0, action);
>>> + seccomp_log(this_syscall, 0, action);
>>> return -1;
>>> }
>>> #else
>>> @@ -917,12 +945,96 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
>>> #define SECCOMP_RET_TRACE_NAME "trace"
>>> #define SECCOMP_RET_ALLOW_NAME "allow"
>>>
>>> +/* Largest strlen() of all action names */
>>> +#define SECCOMP_RET_MAX_NAME_LEN 5
>>> +
>>> static char seccomp_actions_avail[] = SECCOMP_RET_KILL_NAME " "
>>> SECCOMP_RET_TRAP_NAME " "
>>> SECCOMP_RET_ERRNO_NAME " "
>>> SECCOMP_RET_TRACE_NAME " "
>>> SECCOMP_RET_ALLOW_NAME;
>>>
>>> +struct seccomp_action_name {
>>> + u32 action;
>>> + const char *name;
>>> +};
>>> +
>>> +static struct seccomp_action_name seccomp_action_names[] = {
>>
>> As long as I'm nit-picking, this can be const too. :)
>
> I'll have to cast to a non-const pointer when assigning ctl_table.data
> but I think that's fine in this case.
I was confused about which array you were talking about. I thought you
were talking about seccomp_actions_avail[].
No casts are needed when making seccomp_action_names[] const.
Tyler
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