On 09/28/2015 04:54 PM, Andy Lutomirski wrote:
On Mon, Sep 28, 2015 at 11:17 AM, Chris Metcalf <cmetcalf@xxxxxxxxxx> 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@xxxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
