diff options
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 325 |
1 files changed, 147 insertions, 178 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index ca1186eef938..1bf3c39d6109 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -262,7 +262,7 @@ next_signal(struct sigpending *pending, sigset_t *mask) return sig; } -static struct sigqueue *__sigqueue_alloc(struct task_struct *t, unsigned int __nocast flags, +static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags, int override_rlimit) { struct sigqueue *q = NULL; @@ -277,7 +277,6 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, unsigned int __n } else { INIT_LIST_HEAD(&q->list); q->flags = 0; - q->lock = NULL; q->user = get_uid(t->user); } return(q); @@ -397,20 +396,8 @@ void __exit_signal(struct task_struct *tsk) flush_sigqueue(&tsk->pending); if (sig) { /* - * We are cleaning up the signal_struct here. We delayed - * calling exit_itimers until after flush_sigqueue, just in - * case our thread-local pending queue contained a queued - * timer signal that would have been cleared in - * exit_itimers. When that called sigqueue_free, it would - * attempt to re-take the tasklist_lock and deadlock. This - * can never happen if we ensure that all queues the - * timer's signal might be queued on have been flushed - * first. The shared_pending queue, and our own pending - * queue are the only queues the timer could be on, since - * there are no other threads left in the group and timer - * signals are constrained to threads inside the group. + * We are cleaning up the signal_struct here. */ - exit_itimers(sig); exit_thread_group_keys(sig); kmem_cache_free(signal_cachep, sig); } @@ -418,6 +405,8 @@ void __exit_signal(struct task_struct *tsk) void exit_signal(struct task_struct *tsk) { + atomic_dec(&tsk->signal->live); + write_lock_irq(&tasklist_lock); __exit_signal(tsk); write_unlock_irq(&tasklist_lock); @@ -578,7 +567,8 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) * is to alert stop-signal processing code when another * processor has come along and cleared the flag. */ - tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; + if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) + tsk->signal->flags |= SIGNAL_STOP_DEQUEUED; } if ( signr && ((info->si_code & __SI_MASK) == __SI_TIMER) && @@ -661,8 +651,7 @@ static int check_kill_permission(int sig, struct siginfo *info, if (!valid_signal(sig)) return error; error = -EPERM; - if ((!info || ((unsigned long)info != 1 && - (unsigned long)info != 2 && SI_FROMUSER(info))) + if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) && ((sig != SIGCONT) || (current->signal->session != t->signal->session)) && (current->euid ^ t->suid) && (current->euid ^ t->uid) @@ -678,7 +667,7 @@ static int check_kill_permission(int sig, struct siginfo *info, /* forward decl */ static void do_notify_parent_cldstop(struct task_struct *tsk, - struct task_struct *parent, + int to_self, int why); /* @@ -692,7 +681,7 @@ static void handle_stop_signal(int sig, struct task_struct *p) { struct task_struct *t; - if (p->flags & SIGNAL_GROUP_EXIT) + if (p->signal->flags & SIGNAL_GROUP_EXIT) /* * The process is in the middle of dying already. */ @@ -729,14 +718,7 @@ static void handle_stop_signal(int sig, struct task_struct *p) p->signal->group_stop_count = 0; p->signal->flags = SIGNAL_STOP_CONTINUED; spin_unlock(&p->sighand->siglock); - if (p->ptrace & PT_PTRACED) - do_notify_parent_cldstop(p, p->parent, - CLD_STOPPED); - else - do_notify_parent_cldstop( - p->group_leader, - p->group_leader->real_parent, - CLD_STOPPED); + do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED); spin_lock(&p->sighand->siglock); } rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending); @@ -777,14 +759,7 @@ static void handle_stop_signal(int sig, struct task_struct *p) p->signal->flags = SIGNAL_STOP_CONTINUED; p->signal->group_exit_code = 0; spin_unlock(&p->sighand->siglock); - if (p->ptrace & PT_PTRACED) - do_notify_parent_cldstop(p, p->parent, - CLD_CONTINUED); - else - do_notify_parent_cldstop( - p->group_leader, - p->group_leader->real_parent, - CLD_CONTINUED); + do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED); spin_lock(&p->sighand->siglock); } else { /* @@ -813,7 +788,7 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, * fast-pathed signals for kernel-internal things like SIGSTOP * or SIGKILL. */ - if ((unsigned long)info == 2) + if (info == SEND_SIG_FORCED) goto out_set; /* Real-time signals must be queued if sent by sigqueue, or @@ -825,19 +800,19 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, pass on the info struct. */ q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN && - ((unsigned long) info < 2 || + (is_si_special(info) || info->si_code >= 0))); if (q) { list_add_tail(&q->list, &signals->list); switch ((unsigned long) info) { - case 0: + case (unsigned long) SEND_SIG_NOINFO: q->info.si_signo = sig; q->info.si_errno = 0; q->info.si_code = SI_USER; q->info.si_pid = current->pid; q->info.si_uid = current->uid; break; - case 1: + case (unsigned long) SEND_SIG_PRIV: q->info.si_signo = sig; q->info.si_errno = 0; q->info.si_code = SI_KERNEL; @@ -848,20 +823,13 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, copy_siginfo(&q->info, info); break; } - } else { - if (sig >= SIGRTMIN && info && (unsigned long)info != 1 - && info->si_code != SI_USER) + } else if (!is_si_special(info)) { + if (sig >= SIGRTMIN && info->si_code != SI_USER) /* * Queue overflow, abort. We may abort if the signal was rt * and sent by user using something other than kill(). */ return -EAGAIN; - if (((unsigned long)info > 1) && (info->si_code == SI_TIMER)) - /* - * Set up a return to indicate that we dropped - * the signal. - */ - ret = info->si_sys_private; } out_set: @@ -882,12 +850,6 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) BUG(); assert_spin_locked(&t->sighand->siglock); - if (((unsigned long)info > 2) && (info->si_code == SI_TIMER)) - /* - * Set up a return to indicate that we dropped the signal. - */ - ret = info->si_sys_private; - /* Short-circuit ignored signals. */ if (sig_ignored(t, sig)) goto out; @@ -917,11 +879,13 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) int ret; spin_lock_irqsave(&t->sighand->siglock, flags); - if (sigismember(&t->blocked, sig) || t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) { + if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) { t->sighand->action[sig-1].sa.sa_handler = SIG_DFL; + } + if (sigismember(&t->blocked, sig)) { sigdelset(&t->blocked, sig); - recalc_sigpending_tsk(t); } + recalc_sigpending_tsk(t); ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); @@ -931,15 +895,7 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) void force_sig_specific(int sig, struct task_struct *t) { - unsigned long int flags; - - spin_lock_irqsave(&t->sighand->siglock, flags); - if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) - t->sighand->action[sig-1].sa.sa_handler = SIG_DFL; - sigdelset(&t->blocked, sig); - recalc_sigpending_tsk(t); - specific_send_sig_info(sig, (void *)2, t); - spin_unlock_irqrestore(&t->sighand->siglock, flags); + force_sig_info(sig, SEND_SIG_FORCED, t); } /* @@ -950,34 +906,31 @@ force_sig_specific(int sig, struct task_struct *t) * as soon as they're available, so putting the signal on the shared queue * will be equivalent to sending it to one such thread. */ -#define wants_signal(sig, p, mask) \ - (!sigismember(&(p)->blocked, sig) \ - && !((p)->state & mask) \ - && !((p)->flags & PF_EXITING) \ - && (task_curr(p) || !signal_pending(p))) - +static inline int wants_signal(int sig, struct task_struct *p) +{ + if (sigismember(&p->blocked, sig)) + return 0; + if (p->flags & PF_EXITING) + return 0; + if (sig == SIGKILL) + return 1; + if (p->state & (TASK_STOPPED | TASK_TRACED)) + return 0; + return task_curr(p) || !signal_pending(p); +} static void __group_complete_signal(int sig, struct task_struct *p) { - unsigned int mask; struct task_struct *t; /* - * Don't bother traced and stopped tasks (but - * SIGKILL will punch through that). - */ - mask = TASK_STOPPED | TASK_TRACED; - if (sig == SIGKILL) - mask = 0; - - /* * Now find a thread we can wake up to take the signal off the queue. * * If the main thread wants the signal, it gets first crack. * Probably the least surprising to the average bear. */ - if (wants_signal(sig, p, mask)) + if (wants_signal(sig, p)) t = p; else if (thread_group_empty(p)) /* @@ -995,7 +948,7 @@ __group_complete_signal(int sig, struct task_struct *p) t = p->signal->curr_target = p; BUG_ON(t->tgid != p->tgid); - while (!wants_signal(sig, t, mask)) { + while (!wants_signal(sig, t)) { t = next_thread(t); if (t == p->signal->curr_target) /* @@ -1077,12 +1030,6 @@ __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p) assert_spin_locked(&p->sighand->siglock); handle_stop_signal(sig, p); - if (((unsigned long)info > 2) && (info->si_code == SI_TIMER)) - /* - * Set up a return to indicate that we dropped the signal. - */ - ret = info->si_sys_private; - /* Short-circuit ignored signals. */ if (sig_ignored(p, sig)) return ret; @@ -1135,8 +1082,8 @@ void zap_other_threads(struct task_struct *p) if (t != p->group_leader) t->exit_signal = -1; + /* SIGKILL will be handled before any pending SIGSTOP */ sigaddset(&t->pending.signal, SIGKILL); - rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); signal_wake_up(t, 1); } } @@ -1209,6 +1156,40 @@ kill_proc_info(int sig, struct siginfo *info, pid_t pid) return error; } +/* like kill_proc_info(), but doesn't use uid/euid of "current" */ +int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid, + uid_t uid, uid_t euid) +{ + int ret = -EINVAL; + struct task_struct *p; + + if (!valid_signal(sig)) + return ret; + + read_lock(&tasklist_lock); + p = find_task_by_pid(pid); + if (!p) { + ret = -ESRCH; + goto out_unlock; + } + if ((!info || ((unsigned long)info != 1 && + (unsigned long)info != 2 && SI_FROMUSER(info))) + && (euid != p->suid) && (euid != p->uid) + && (uid != p->suid) && (uid != p->uid)) { + ret = -EPERM; + goto out_unlock; + } + if (sig && p->sighand) { + unsigned long flags; + spin_lock_irqsave(&p->sighand->siglock, flags); + ret = __group_send_sig_info(sig, info, p); + spin_unlock_irqrestore(&p->sighand->siglock, flags); + } +out_unlock: + read_unlock(&tasklist_lock); + return ret; +} +EXPORT_SYMBOL_GPL(kill_proc_info_as_uid); /* * kill_something_info() interprets pid in interesting ways just like kill(2). @@ -1278,10 +1259,13 @@ send_sig_info(int sig, struct siginfo *info, struct task_struct *p) return ret; } +#define __si_special(priv) \ + ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO) + int send_sig(int sig, struct task_struct *p, int priv) { - return send_sig_info(sig, (void*)(long)(priv != 0), p); + return send_sig_info(sig, __si_special(priv), p); } /* @@ -1301,7 +1285,7 @@ send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p) void force_sig(int sig, struct task_struct *p) { - force_sig_info(sig, (void*)1L, p); + force_sig_info(sig, SEND_SIG_PRIV, p); } /* @@ -1326,13 +1310,13 @@ force_sigsegv(int sig, struct task_struct *p) int kill_pg(pid_t pgrp, int sig, int priv) { - return kill_pg_info(sig, (void *)(long)(priv != 0), pgrp); + return kill_pg_info(sig, __si_special(priv), pgrp); } int kill_proc(pid_t pid, int sig, int priv) { - return kill_proc_info(sig, (void *)(long)(priv != 0), pid); + return kill_proc_info(sig, __si_special(priv), pid); } /* @@ -1363,11 +1347,12 @@ void sigqueue_free(struct sigqueue *q) * pending queue. */ if (unlikely(!list_empty(&q->list))) { - read_lock(&tasklist_lock); - spin_lock_irqsave(q->lock, flags); + spinlock_t *lock = ¤t->sighand->siglock; + read_lock(&tasklist_lock); + spin_lock_irqsave(lock, flags); if (!list_empty(&q->list)) list_del_init(&q->list); - spin_unlock_irqrestore(q->lock, flags); + spin_unlock_irqrestore(lock, flags); read_unlock(&tasklist_lock); } q->flags &= ~SIGQUEUE_PREALLOC; @@ -1380,16 +1365,16 @@ send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) unsigned long flags; int ret = 0; - /* - * We need the tasklist lock even for the specific - * thread case (when we don't need to follow the group - * lists) in order to avoid races with "p->sighand" - * going away or changing from under us. - */ BUG_ON(!(q->flags & SIGQUEUE_PREALLOC)); - read_lock(&tasklist_lock); + read_lock(&tasklist_lock); + + if (unlikely(p->flags & PF_EXITING)) { + ret = -1; + goto out_err; + } + spin_lock_irqsave(&p->sighand->siglock, flags); - + if (unlikely(!list_empty(&q->list))) { /* * If an SI_TIMER entry is already queue just increment @@ -1399,14 +1384,13 @@ send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) BUG(); q->info.si_overrun++; goto out; - } + } /* Short-circuit ignored signals. */ if (sig_ignored(p, sig)) { ret = 1; goto out; } - q->lock = &p->sighand->siglock; list_add_tail(&q->list, &p->pending.list); sigaddset(&p->pending.signal, sig); if (!sigismember(&p->blocked, sig)) @@ -1414,8 +1398,10 @@ send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) out: spin_unlock_irqrestore(&p->sighand->siglock, flags); +out_err: read_unlock(&tasklist_lock); - return(ret); + + return ret; } int @@ -1452,7 +1438,6 @@ send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) * We always use the shared queue for process-wide signals, * to avoid several races. */ - q->lock = &p->sighand->siglock; list_add_tail(&q->list, &p->signal->shared_pending.list); sigaddset(&p->signal->shared_pending.signal, sig); @@ -1542,14 +1527,20 @@ void do_notify_parent(struct task_struct *tsk, int sig) spin_unlock_irqrestore(&psig->siglock, flags); } -static void -do_notify_parent_cldstop(struct task_struct *tsk, struct task_struct *parent, - int why) +static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why) { struct siginfo info; unsigned long flags; + struct task_struct *parent; struct sighand_struct *sighand; + if (to_self) + parent = tsk->parent; + else { + tsk = tsk->group_leader; + parent = tsk->real_parent; + } + info.si_signo = SIGCHLD; info.si_errno = 0; info.si_pid = tsk->pid; @@ -1618,8 +1609,7 @@ static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info) !(current->ptrace & PT_ATTACHED)) && (likely(current->parent->signal != current->signal) || !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) { - do_notify_parent_cldstop(current, current->parent, - CLD_TRAPPED); + do_notify_parent_cldstop(current, 1, CLD_TRAPPED); read_unlock(&tasklist_lock); schedule(); } else { @@ -1668,25 +1658,25 @@ void ptrace_notify(int exit_code) static void finish_stop(int stop_count) { + int to_self; + /* * If there are no other threads in the group, or if there is * a group stop in progress and we are the last to stop, * report to the parent. When ptraced, every thread reports itself. */ - if (stop_count < 0 || (current->ptrace & PT_PTRACED)) { - read_lock(&tasklist_lock); - do_notify_parent_cldstop(current, current->parent, - CLD_STOPPED); - read_unlock(&tasklist_lock); - } - else if (stop_count == 0) { - read_lock(&tasklist_lock); - do_notify_parent_cldstop(current->group_leader, - current->group_leader->real_parent, - CLD_STOPPED); - read_unlock(&tasklist_lock); - } + if (stop_count < 0 || (current->ptrace & PT_PTRACED)) + to_self = 1; + else if (stop_count == 0) + to_self = 0; + else + goto out; + + read_lock(&tasklist_lock); + do_notify_parent_cldstop(current, to_self, CLD_STOPPED); + read_unlock(&tasklist_lock); +out: schedule(); /* * Now we don't run again until continued. @@ -1773,7 +1763,8 @@ do_signal_stop(int signr) * stop is always done with the siglock held, * so this check has no races. */ - if (t->state < TASK_STOPPED) { + if (!t->exit_state && + !(t->state & (TASK_STOPPED|TASK_TRACED))) { stop_count++; signal_wake_up(t, 0); } @@ -1865,9 +1856,9 @@ relock: /* Let the debugger run. */ ptrace_stop(signr, signr, info); - /* We're back. Did the debugger cancel the sig? */ + /* We're back. Did the debugger cancel the sig or group_exit? */ signr = current->exit_code; - if (signr == 0) + if (signr == 0 || current->signal->flags & SIGNAL_GROUP_EXIT) continue; current->exit_code = 0; @@ -2228,8 +2219,7 @@ sys_rt_sigtimedwait(const sigset_t __user *uthese, recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); - current->state = TASK_INTERRUPTIBLE; - timeout = schedule_timeout(timeout); + timeout = schedule_timeout_interruptible(timeout); try_to_freeze(); spin_lock_irq(¤t->sighand->siglock); @@ -2270,26 +2260,13 @@ sys_kill(int pid, int sig) return kill_something_info(sig, &info, pid); } -/** - * sys_tgkill - send signal to one specific thread - * @tgid: the thread group ID of the thread - * @pid: the PID of the thread - * @sig: signal to be sent - * - * This syscall also checks the tgid and returns -ESRCH even if the PID - * exists but it's not belonging to the target process anymore. This - * method solves the problem of threads exiting and PIDs getting reused. - */ -asmlinkage long sys_tgkill(int tgid, int pid, int sig) +static int do_tkill(int tgid, int pid, int sig) { - struct siginfo info; int error; + struct siginfo info; struct task_struct *p; - /* This is only valid for single tasks */ - if (pid <= 0 || tgid <= 0) - return -EINVAL; - + error = -ESRCH; info.si_signo = sig; info.si_errno = 0; info.si_code = SI_TKILL; @@ -2298,8 +2275,7 @@ asmlinkage long sys_tgkill(int tgid, int pid, int sig) read_lock(&tasklist_lock); p = find_task_by_pid(pid); - error = -ESRCH; - if (p && (p->tgid == tgid)) { + if (p && (tgid <= 0 || p->tgid == tgid)) { error = check_kill_permission(sig, &info, p); /* * The null signal is a permissions and process existence @@ -2313,47 +2289,40 @@ asmlinkage long sys_tgkill(int tgid, int pid, int sig) } } read_unlock(&tasklist_lock); + return error; } +/** + * sys_tgkill - send signal to one specific thread + * @tgid: the thread group ID of the thread + * @pid: the PID of the thread + * @sig: signal to be sent + * + * This syscall also checks the tgid and returns -ESRCH even if the PID + * exists but it's not belonging to the target process anymore. This + * method solves the problem of threads exiting and PIDs getting reused. + */ +asmlinkage long sys_tgkill(int tgid, int pid, int sig) +{ + /* This is only valid for single tasks */ + if (pid <= 0 || tgid <= 0) + return -EINVAL; + + return do_tkill(tgid, pid, sig); +} + /* * Send a signal to only one task, even if it's a CLONE_THREAD task. */ asmlinkage long sys_tkill(int pid, int sig) { - struct siginfo info; - int error; - struct task_struct *p; - /* This is only valid for single tasks */ if (pid <= 0) return -EINVAL; - info.si_signo = sig; - info.si_errno = 0; - info.si_code = SI_TKILL; - info.si_pid = current->tgid; - info.si_uid = current->uid; - - read_lock(&tasklist_lock); - p = find_task_by_pid(pid); - error = -ESRCH; - if (p) { - error = check_kill_permission(sig, &info, p); - /* - * The null signal is a permissions and process existence - * probe. No signal is actually delivered. - */ - if (!error && sig && p->sighand) { - spin_lock_irq(&p->sighand->siglock); - handle_stop_signal(sig, p); - error = specific_send_sig_info(sig, &info, p); - spin_unlock_irq(&p->sighand->siglock); - } - } - read_unlock(&tasklist_lock); - return error; + return do_tkill(0, pid, sig); } asmlinkage long |