On 09/28/2015 04:54 PM, Andy Lutomirski wrote:
On Mon, Sep 28, 2015 at 11:17 AM, Chris Metcalf <cmetc...@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 <cmetc...@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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