posix-timers: Move compat_timer_create() to native, get rid of set_fs()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-14-viro@ZenIV.linux.org.uk

3 files changed, 42 insertions, 36 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 582c38bfdf60..4544eb63edfa 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -580,24 +580,6 @@ int put_compat_itimerspec(struct compat_itimerspec __user *dst,
         return 0;
 }
 
-COMPAT_SYSCALL_DEFINE3(timer_create, clockid_t, which_clock,
-                       struct compat_sigevent __user *, timer_event_spec,
-                       timer_t __user *, created_timer_id)
-{
-        struct sigevent __user *event = NULL;
-
-        if (timer_event_spec) {
-                struct sigevent kevent;
-
-                event = compat_alloc_user_space(sizeof(*event));
-                if (get_compat_sigevent(&kevent, timer_event_spec) ||
-                    copy_to_user(event, &kevent, sizeof(*event)))
-                        return -EFAULT;
-        }
-
-        return sys_timer_create(which_clock, event, created_timer_id);
-}
-
 /*
  * We currently only need the following fields from the sigevent
  * structure: sigev_value, sigev_signo, sig_notify and (sometimes
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index a375c31cb352..38f3b20efa29 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -41,6 +41,7 @@ SYS_NI(setitimer);
 #ifdef __ARCH_WANT_SYS_ALARM
 SYS_NI(alarm);
 #endif
+COMPAT_SYS_NI(timer_create);
 COMPAT_SYS_NI(clock_adjtime);
 COMPAT_SYS_NI(timer_settime);
 COMPAT_SYS_NI(timer_gettime);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 61a5fb91a3c7..c9f45a84fb8b 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -490,15 +490,12 @@ static int common_timer_create(struct k_itimer *new_timer)
 }
 
 /* Create a POSIX.1b interval timer. */
-
-SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
-                struct sigevent __user *, timer_event_spec,
-                timer_t __user *, created_timer_id)
+static int do_timer_create(clockid_t which_clock, struct sigevent *event,
+                           timer_t __user *created_timer_id)
 {
         const struct k_clock *kc = clockid_to_kclock(which_clock);
         struct k_itimer *new_timer;
         int error, new_timer_id;
-        sigevent_t event;
         int it_id_set = IT_ID_NOT_SET;
 
         if (!kc)
@@ -523,29 +520,25 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
         new_timer->kclock = kc;
         new_timer->it_overrun = -1;
 
-        if (timer_event_spec) {
-                if (copy_from_user(&event, timer_event_spec, sizeof (event))) {
-                        error = -EFAULT;
-                        goto out;
-                }
+        if (event) {
                 rcu_read_lock();
-                new_timer->it_pid = get_pid(good_sigevent(&event));
+                new_timer->it_pid = get_pid(good_sigevent(event));
                 rcu_read_unlock();
                 if (!new_timer->it_pid) {
                         error = -EINVAL;
                         goto out;
                 }
+                new_timer->it_sigev_notify     = event->sigev_notify;
+                new_timer->sigq->info.si_signo = event->sigev_signo;
+                new_timer->sigq->info.si_value = event->sigev_value;
         } else {
-                memset(&event.sigev_value, 0, sizeof(event.sigev_value));
-                event.sigev_notify = SIGEV_SIGNAL;
-                event.sigev_signo = SIGALRM;
-                event.sigev_value.sival_int = new_timer->it_id;
+                new_timer->it_sigev_notify     = SIGEV_SIGNAL;
+                new_timer->sigq->info.si_signo = SIGALRM;
+                memset(&new_timer->sigq->info.si_value, 0, sizeof(sigval_t));
+                new_timer->sigq->info.si_value.sival_int = new_timer->it_id;
                 new_timer->it_pid = get_pid(task_tgid(current));
         }
 
-        new_timer->it_sigev_notify     = event.sigev_notify;
-        new_timer->sigq->info.si_signo = event.sigev_signo;
-        new_timer->sigq->info.si_value = event.sigev_value;
         new_timer->sigq->info.si_tid   = new_timer->it_id;
         new_timer->sigq->info.si_code  = SI_TIMER;
 
@@ -576,6 +569,36 @@ out:
         return error;
 }
 
+SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock,
+                struct sigevent __user *, timer_event_spec,
+                timer_t __user *, created_timer_id)
+{
+        if (timer_event_spec) {
+                sigevent_t event;
+
+                if (copy_from_user(&event, timer_event_spec, sizeof (event)))
+                        return -EFAULT;
+                return do_timer_create(which_clock, &event, created_timer_id);
+        }
+        return do_timer_create(which_clock, NULL, created_timer_id);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE3(timer_create, clockid_t, which_clock,
+                       struct compat_sigevent __user *, timer_event_spec,
+                       timer_t __user *, created_timer_id)
+{
+        if (timer_event_spec) {
+                sigevent_t event;
+
+                if (get_compat_sigevent(&event, timer_event_spec))
+                        return -EFAULT;
+                return do_timer_create(which_clock, &event, created_timer_id);
+        }
+        return do_timer_create(which_clock, NULL, created_timer_id);
+}
+#endif
+
 /*
  * Locking issues: We need to protect the result of the id look up until
  * we get the timer locked down so it is not deleted under us.  The