Messages in this thread | | | Subject | Re: [PATCH v7 04/11] task_isolation: provide strict mode configurable signal | From | Chris Metcalf <> | Date | Mon, 28 Sep 2015 17:54:59 -0400 |
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On 09/28/2015 04:54 PM, Andy Lutomirski wrote: > On Mon, Sep 28, 2015 at 11:17 AM, Chris Metcalf <cmetcalf@ezchip.com> wrote: >> Allow userspace to override the default SIGKILL delivered >> when a task_isolation process in STRICT mode does a syscall >> or otherwise synchronously enters the kernel. >> >> In addition to being able to set the signal, we now also >> pass whether or not the interruption was from a syscall in >> the si_code field of the siginfo. >> >> Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com> >> --- >> include/uapi/linux/prctl.h | 2 ++ >> kernel/isolation.c | 17 +++++++++++++---- >> 2 files changed, 15 insertions(+), 4 deletions(-) >> >> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h >> index 2b8038b0d1e1..a5582ace987f 100644 >> --- a/include/uapi/linux/prctl.h >> +++ b/include/uapi/linux/prctl.h >> @@ -202,5 +202,7 @@ struct prctl_mm_map { >> #define PR_GET_TASK_ISOLATION 49 >> # define PR_TASK_ISOLATION_ENABLE (1 << 0) >> # define PR_TASK_ISOLATION_STRICT (1 << 1) >> +# define PR_TASK_ISOLATION_SET_SIG(sig) (((sig) & 0x7f) << 8) >> +# define PR_TASK_ISOLATION_GET_SIG(bits) (((bits) >> 8) & 0x7f) >> >> #endif /* _LINUX_PRCTL_H */ >> diff --git a/kernel/isolation.c b/kernel/isolation.c >> index 3779ba670472..44bafcd08bca 100644 >> --- a/kernel/isolation.c >> +++ b/kernel/isolation.c >> @@ -77,14 +77,23 @@ void task_isolation_enter(void) >> } >> } >> >> -static void kill_task_isolation_strict_task(void) >> +static void kill_task_isolation_strict_task(int is_syscall) >> { >> + siginfo_t info = {}; >> + int sig; >> + >> /* RCU should have been enabled prior to this point. */ >> RCU_LOCKDEP_WARN(!rcu_is_watching(), "kernel entry without RCU"); >> >> dump_stack(); >> current->task_isolation_flags &= ~PR_TASK_ISOLATION_ENABLE; >> - send_sig(SIGKILL, current, 1); >> + >> + sig = PR_TASK_ISOLATION_GET_SIG(current->task_isolation_flags); >> + if (sig == 0) >> + sig = SIGKILL; >> + info.si_signo = sig; >> + info.si_code = is_syscall; > I think this needs real SI_ defines.
Yeah, it's a fair point, but of course SIGKILL has no SI_ defines at all right now. I'm tempted to suggest we just back out setting si_code altogether. It might be worth a one-line console message (a la show_signal_message()), and use that to pack in the extra information, instead of trying to fuss with the siginfo data.
>> + send_sig_info(sig, &info, current); >> } >> >> /* >> @@ -103,7 +112,7 @@ void task_isolation_syscall(int syscall) >> >> pr_warn("%s/%d: task_isolation strict mode violated by syscall %d\n", >> current->comm, current->pid, syscall); >> - kill_task_isolation_strict_task(); >> + kill_task_isolation_strict_task(1); > No magic numbers please.
I think mooted by the above, but, good point.
-- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com
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