[PATCH v6 4/6] task_isolation: provide strict mode configurable signal

Chris Metcalf
2015-08-25T19:57:29Z

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 e16e13911e8a..2a4ddc890e22 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -195,5 +195,7 @@ struct prctl_mm_map {
#define PR_GET_TASK_ISOLATION 48
# 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 a89a6e9adfb4..b776aa632c8f 100644
--- a/kernel/isolation.c
+++ b/kernel/isolation.c
@@ -75,11 +75,20 @@ 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;
+
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;
+ send_sig_info(sig, &info, current);
}

/*
@@ -98,7 +107,7 @@ 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);
}

/*
@@ -109,5 +118,5 @@ void task_isolation_exception(void)
{
pr_warn("%s/%d: task_isolation strict mode violated by exception\n",
current->comm, current->pid);
- kill_task_isolation_strict_task();
+ kill_task_isolation_strict_task(0);
}
--
2.1.2