From 24122c7f4969adeeaeca3fb1656a31569e9aa59b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 20 Jul 2018 14:30:23 -0500 Subject: signal: Pass pid and pid type into send_sigqueue Make the code more maintainable by performing more of the signal related work in send_sigqueue. A quick inspection of do_timer_create will show that this code path does not lookup a thread group by a thread's pid. Making it safe to find the task pointed to by it_pid with "pid_task(it_pid, type)"; This supports the changes needed in fork to tell if a signal was sent to a single process or a group of processes. Having the pid to task transition in signal.c will also make it easier to sort out races with de_thread and and the thread group leader exiting when it comes time to address that. Signed-off-by: "Eric W. Biederman" --- include/linux/sched/signal.h | 2 +- kernel/signal.c | 14 +++++++++----- kernel/time/posix-timers.c | 13 ++++--------- 3 files changed, 14 insertions(+), 15 deletions(-) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index ee30a5ba475f..94558ffa82ab 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -330,7 +330,7 @@ extern int send_sig(int, struct task_struct *, int); extern int zap_other_threads(struct task_struct *p); extern struct sigqueue *sigqueue_alloc(void); extern void sigqueue_free(struct sigqueue *); -extern int send_sigqueue(struct sigqueue *, struct task_struct *, int group); +extern int send_sigqueue(struct sigqueue *, struct pid *, enum pid_type); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); static inline int restart_syscall(void) diff --git a/kernel/signal.c b/kernel/signal.c index 8d8a940422a8..40feb14e276d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1664,17 +1664,20 @@ void sigqueue_free(struct sigqueue *q) __sigqueue_free(q); } -int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) +int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) { int sig = q->info.si_signo; struct sigpending *pending; + struct task_struct *t; unsigned long flags; int ret, result; BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); ret = -1; - if (!likely(lock_task_sighand(t, &flags))) + rcu_read_lock(); + t = pid_task(pid, type); + if (!t || !likely(lock_task_sighand(t, &flags))) goto ret; ret = 1; /* the signal is ignored */ @@ -1696,15 +1699,16 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) q->info.si_overrun = 0; signalfd_notify(t, sig); - pending = group ? &t->signal->shared_pending : &t->pending; + pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending; list_add_tail(&q->list, &pending->list); sigaddset(&pending->signal, sig); - complete_signal(sig, t, group); + complete_signal(sig, t, type != PIDTYPE_PID); result = TRACE_SIGNAL_DELIVERED; out: - trace_signal_generate(sig, &q->info, t, group, result); + trace_signal_generate(sig, &q->info, t, type != PIDTYPE_PID, result); unlock_task_sighand(t, &flags); ret: + rcu_read_unlock(); return ret; } diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index 2bdf08a2bae9..2d2e739fbc57 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -332,8 +332,8 @@ void posixtimer_rearm(struct siginfo *info) int posix_timer_event(struct k_itimer *timr, int si_private) { - struct task_struct *task; - int shared, ret = -1; + enum pid_type type; + int ret = -1; /* * FIXME: if ->sigq is queued we can race with * dequeue_signal()->posixtimer_rearm(). @@ -347,13 +347,8 @@ int posix_timer_event(struct k_itimer *timr, int si_private) */ timr->sigq->info.si_sys_private = si_private; - rcu_read_lock(); - task = pid_task(timr->it_pid, PIDTYPE_PID); - if (task) { - shared = !(timr->it_sigev_notify & SIGEV_THREAD_ID); - ret = send_sigqueue(timr->sigq, task, shared); - } - rcu_read_unlock(); + type = !(timr->it_sigev_notify & SIGEV_THREAD_ID) ? PIDTYPE_TGID : PIDTYPE_PID; + ret = send_sigqueue(timr->sigq, timr->it_pid, type); /* If we failed to send the signal the timer stops. */ return ret > 0; } -- cgit