3320 lines
85 KiB
C
3320 lines
85 KiB
C
/*
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* linux/kernel/signal.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
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*
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* 2003-06-02 Jim Houston - Concurrent Computer Corp.
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* Changes to use preallocated sigqueue structures
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* to allow signals to be sent reliably.
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*/
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/tty.h>
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#include <linux/binfmts.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/ptrace.h>
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#include <linux/signal.h>
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#include <linux/signalfd.h>
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#include <linux/ratelimit.h>
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#include <linux/tracehook.h>
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#include <linux/capability.h>
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#include <linux/freezer.h>
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#include <linux/pid_namespace.h>
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#include <linux/nsproxy.h>
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#include <linux/user_namespace.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/signal.h>
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#include <asm/param.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/siginfo.h>
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#include <asm/cacheflush.h>
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#include "audit.h" /* audit_signal_info() */
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/*
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* SLAB caches for signal bits.
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*/
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static struct kmem_cache *sigqueue_cachep;
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int print_fatal_signals __read_mostly;
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static void __user *sig_handler(struct task_struct *t, int sig)
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{
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return t->sighand->action[sig - 1].sa.sa_handler;
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}
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static int sig_handler_ignored(void __user *handler, int sig)
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{
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/* Is it explicitly or implicitly ignored? */
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return handler == SIG_IGN ||
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(handler == SIG_DFL && sig_kernel_ignore(sig));
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}
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static int sig_task_ignored(struct task_struct *t, int sig, bool force)
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{
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void __user *handler;
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handler = sig_handler(t, sig);
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if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
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handler == SIG_DFL && !force)
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return 1;
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return sig_handler_ignored(handler, sig);
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}
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static int sig_ignored(struct task_struct *t, int sig, bool force)
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{
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/*
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* Blocked signals are never ignored, since the
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* signal handler may change by the time it is
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* unblocked.
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*/
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if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
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return 0;
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if (!sig_task_ignored(t, sig, force))
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return 0;
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/*
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* Tracers may want to know about even ignored signals.
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*/
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return !t->ptrace;
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}
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/*
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* Re-calculate pending state from the set of locally pending
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* signals, globally pending signals, and blocked signals.
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*/
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static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
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{
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unsigned long ready;
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long i;
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switch (_NSIG_WORDS) {
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default:
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for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
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ready |= signal->sig[i] &~ blocked->sig[i];
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break;
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case 4: ready = signal->sig[3] &~ blocked->sig[3];
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ready |= signal->sig[2] &~ blocked->sig[2];
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ready |= signal->sig[1] &~ blocked->sig[1];
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ready |= signal->sig[0] &~ blocked->sig[0];
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break;
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case 2: ready = signal->sig[1] &~ blocked->sig[1];
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ready |= signal->sig[0] &~ blocked->sig[0];
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break;
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case 1: ready = signal->sig[0] &~ blocked->sig[0];
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}
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return ready != 0;
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}
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#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
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static int recalc_sigpending_tsk(struct task_struct *t)
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{
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if ((t->jobctl & JOBCTL_PENDING_MASK) ||
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PENDING(&t->pending, &t->blocked) ||
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PENDING(&t->signal->shared_pending, &t->blocked)) {
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set_tsk_thread_flag(t, TIF_SIGPENDING);
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return 1;
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}
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/*
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* We must never clear the flag in another thread, or in current
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* when it's possible the current syscall is returning -ERESTART*.
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* So we don't clear it here, and only callers who know they should do.
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*/
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return 0;
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}
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/*
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* After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
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* This is superfluous when called on current, the wakeup is a harmless no-op.
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*/
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void recalc_sigpending_and_wake(struct task_struct *t)
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{
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if (recalc_sigpending_tsk(t))
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signal_wake_up(t, 0);
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}
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void recalc_sigpending(void)
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{
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if (!recalc_sigpending_tsk(current) && !freezing(current))
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clear_thread_flag(TIF_SIGPENDING);
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}
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/* Given the mask, find the first available signal that should be serviced. */
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#define SYNCHRONOUS_MASK \
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(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
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sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))
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int next_signal(struct sigpending *pending, sigset_t *mask)
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{
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unsigned long i, *s, *m, x;
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int sig = 0;
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s = pending->signal.sig;
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m = mask->sig;
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/*
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* Handle the first word specially: it contains the
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* synchronous signals that need to be dequeued first.
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*/
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x = *s &~ *m;
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if (x) {
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if (x & SYNCHRONOUS_MASK)
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x &= SYNCHRONOUS_MASK;
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sig = ffz(~x) + 1;
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return sig;
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}
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switch (_NSIG_WORDS) {
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default:
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for (i = 1; i < _NSIG_WORDS; ++i) {
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x = *++s &~ *++m;
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if (!x)
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continue;
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sig = ffz(~x) + i*_NSIG_BPW + 1;
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break;
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}
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break;
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case 2:
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x = s[1] &~ m[1];
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if (!x)
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break;
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sig = ffz(~x) + _NSIG_BPW + 1;
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break;
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case 1:
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/* Nothing to do */
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break;
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}
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return sig;
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}
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static inline void print_dropped_signal(int sig)
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{
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static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
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if (!print_fatal_signals)
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return;
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if (!__ratelimit(&ratelimit_state))
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return;
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printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
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current->comm, current->pid, sig);
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}
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/**
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* task_set_jobctl_pending - set jobctl pending bits
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* @task: target task
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* @mask: pending bits to set
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*
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* Clear @mask from @task->jobctl. @mask must be subset of
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* %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
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* %JOBCTL_TRAPPING. If stop signo is being set, the existing signo is
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* cleared. If @task is already being killed or exiting, this function
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* becomes noop.
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*
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* CONTEXT:
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* Must be called with @task->sighand->siglock held.
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*
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* RETURNS:
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* %true if @mask is set, %false if made noop because @task was dying.
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*/
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bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
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{
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BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
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JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
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BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
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if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
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return false;
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if (mask & JOBCTL_STOP_SIGMASK)
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task->jobctl &= ~JOBCTL_STOP_SIGMASK;
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task->jobctl |= mask;
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return true;
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}
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/**
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* task_clear_jobctl_trapping - clear jobctl trapping bit
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* @task: target task
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*
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* If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
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* Clear it and wake up the ptracer. Note that we don't need any further
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* locking. @task->siglock guarantees that @task->parent points to the
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* ptracer.
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*
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* CONTEXT:
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* Must be called with @task->sighand->siglock held.
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*/
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void task_clear_jobctl_trapping(struct task_struct *task)
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{
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if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
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task->jobctl &= ~JOBCTL_TRAPPING;
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wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
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}
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}
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/**
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* task_clear_jobctl_pending - clear jobctl pending bits
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* @task: target task
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* @mask: pending bits to clear
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*
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* Clear @mask from @task->jobctl. @mask must be subset of
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* %JOBCTL_PENDING_MASK. If %JOBCTL_STOP_PENDING is being cleared, other
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* STOP bits are cleared together.
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*
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* If clearing of @mask leaves no stop or trap pending, this function calls
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* task_clear_jobctl_trapping().
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*
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* CONTEXT:
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* Must be called with @task->sighand->siglock held.
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*/
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void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
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{
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BUG_ON(mask & ~JOBCTL_PENDING_MASK);
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if (mask & JOBCTL_STOP_PENDING)
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mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
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task->jobctl &= ~mask;
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if (!(task->jobctl & JOBCTL_PENDING_MASK))
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task_clear_jobctl_trapping(task);
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}
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/**
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* task_participate_group_stop - participate in a group stop
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* @task: task participating in a group stop
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*
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* @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
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* Group stop states are cleared and the group stop count is consumed if
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* %JOBCTL_STOP_CONSUME was set. If the consumption completes the group
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* stop, the appropriate %SIGNAL_* flags are set.
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*
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* CONTEXT:
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* Must be called with @task->sighand->siglock held.
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*
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* RETURNS:
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* %true if group stop completion should be notified to the parent, %false
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* otherwise.
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*/
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static bool task_participate_group_stop(struct task_struct *task)
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{
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struct signal_struct *sig = task->signal;
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bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
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WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
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task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
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if (!consume)
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return false;
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if (!WARN_ON_ONCE(sig->group_stop_count == 0))
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sig->group_stop_count--;
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/*
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* Tell the caller to notify completion iff we are entering into a
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* fresh group stop. Read comment in do_signal_stop() for details.
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*/
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if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
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sig->flags = SIGNAL_STOP_STOPPED;
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return true;
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}
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return false;
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}
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/*
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* allocate a new signal queue record
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* - this may be called without locks if and only if t == current, otherwise an
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* appropriate lock must be held to stop the target task from exiting
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*/
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static struct sigqueue *
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__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
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{
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struct sigqueue *q = NULL;
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struct user_struct *user;
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/*
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* Protect access to @t credentials. This can go away when all
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* callers hold rcu read lock.
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*/
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rcu_read_lock();
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user = get_uid(__task_cred(t)->user);
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atomic_inc(&user->sigpending);
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rcu_read_unlock();
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if (override_rlimit ||
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atomic_read(&user->sigpending) <=
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task_rlimit(t, RLIMIT_SIGPENDING)) {
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q = kmem_cache_alloc(sigqueue_cachep, flags);
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} else {
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print_dropped_signal(sig);
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}
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if (unlikely(q == NULL)) {
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atomic_dec(&user->sigpending);
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free_uid(user);
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} else {
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INIT_LIST_HEAD(&q->list);
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q->flags = 0;
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q->user = user;
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}
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return q;
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}
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static void __sigqueue_free(struct sigqueue *q)
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{
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if (q->flags & SIGQUEUE_PREALLOC)
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return;
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atomic_dec(&q->user->sigpending);
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free_uid(q->user);
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kmem_cache_free(sigqueue_cachep, q);
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}
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void flush_sigqueue(struct sigpending *queue)
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{
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struct sigqueue *q;
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sigemptyset(&queue->signal);
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while (!list_empty(&queue->list)) {
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q = list_entry(queue->list.next, struct sigqueue , list);
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list_del_init(&q->list);
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__sigqueue_free(q);
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}
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}
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/*
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* Flush all pending signals for a task.
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*/
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void __flush_signals(struct task_struct *t)
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{
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clear_tsk_thread_flag(t, TIF_SIGPENDING);
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flush_sigqueue(&t->pending);
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flush_sigqueue(&t->signal->shared_pending);
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}
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void flush_signals(struct task_struct *t)
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{
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unsigned long flags;
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spin_lock_irqsave(&t->sighand->siglock, flags);
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__flush_signals(t);
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spin_unlock_irqrestore(&t->sighand->siglock, flags);
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}
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static void __flush_itimer_signals(struct sigpending *pending)
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{
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sigset_t signal, retain;
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struct sigqueue *q, *n;
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signal = pending->signal;
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sigemptyset(&retain);
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list_for_each_entry_safe(q, n, &pending->list, list) {
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int sig = q->info.si_signo;
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if (likely(q->info.si_code != SI_TIMER)) {
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sigaddset(&retain, sig);
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} else {
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sigdelset(&signal, sig);
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list_del_init(&q->list);
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__sigqueue_free(q);
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}
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}
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sigorsets(&pending->signal, &signal, &retain);
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}
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void flush_itimer_signals(void)
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{
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struct task_struct *tsk = current;
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unsigned long flags;
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spin_lock_irqsave(&tsk->sighand->siglock, flags);
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__flush_itimer_signals(&tsk->pending);
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__flush_itimer_signals(&tsk->signal->shared_pending);
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spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
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}
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void ignore_signals(struct task_struct *t)
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{
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int i;
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for (i = 0; i < _NSIG; ++i)
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t->sighand->action[i].sa.sa_handler = SIG_IGN;
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flush_signals(t);
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}
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|
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/*
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* Flush all handlers for a task.
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*/
|
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|
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void
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flush_signal_handlers(struct task_struct *t, int force_default)
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{
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int i;
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struct k_sigaction *ka = &t->sighand->action[0];
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for (i = _NSIG ; i != 0 ; i--) {
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if (force_default || ka->sa.sa_handler != SIG_IGN)
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ka->sa.sa_handler = SIG_DFL;
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ka->sa.sa_flags = 0;
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sigemptyset(&ka->sa.sa_mask);
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ka++;
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}
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}
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|
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int unhandled_signal(struct task_struct *tsk, int sig)
|
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{
|
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void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
|
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if (is_global_init(tsk))
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return 1;
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if (handler != SIG_IGN && handler != SIG_DFL)
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return 0;
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/* if ptraced, let the tracer determine */
|
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return !tsk->ptrace;
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}
|
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|
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/*
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* Notify the system that a driver wants to block all signals for this
|
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* process, and wants to be notified if any signals at all were to be
|
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* sent/acted upon. If the notifier routine returns non-zero, then the
|
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* signal will be acted upon after all. If the notifier routine returns 0,
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* then then signal will be blocked. Only one block per process is
|
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* allowed. priv is a pointer to private data that the notifier routine
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* can use to determine if the signal should be blocked or not.
|
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*/
|
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void
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block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
|
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{
|
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unsigned long flags;
|
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|
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spin_lock_irqsave(¤t->sighand->siglock, flags);
|
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current->notifier_mask = mask;
|
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current->notifier_data = priv;
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current->notifier = notifier;
|
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spin_unlock_irqrestore(¤t->sighand->siglock, flags);
|
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}
|
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|
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/* Notify the system that blocking has ended. */
|
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|
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void
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unblock_all_signals(void)
|
|
{
|
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unsigned long flags;
|
|
|
|
spin_lock_irqsave(¤t->sighand->siglock, flags);
|
|
current->notifier = NULL;
|
|
current->notifier_data = NULL;
|
|
recalc_sigpending();
|
|
spin_unlock_irqrestore(¤t->sighand->siglock, flags);
|
|
}
|
|
|
|
static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
|
|
{
|
|
struct sigqueue *q, *first = NULL;
|
|
|
|
/*
|
|
* Collect the siginfo appropriate to this signal. Check if
|
|
* there is another siginfo for the same signal.
|
|
*/
|
|
list_for_each_entry(q, &list->list, list) {
|
|
if (q->info.si_signo == sig) {
|
|
if (first)
|
|
goto still_pending;
|
|
first = q;
|
|
}
|
|
}
|
|
|
|
sigdelset(&list->signal, sig);
|
|
|
|
if (first) {
|
|
still_pending:
|
|
list_del_init(&first->list);
|
|
copy_siginfo(info, &first->info);
|
|
__sigqueue_free(first);
|
|
} else {
|
|
/*
|
|
* Ok, it wasn't in the queue. This must be
|
|
* a fast-pathed signal or we must have been
|
|
* out of queue space. So zero out the info.
|
|
*/
|
|
info->si_signo = sig;
|
|
info->si_errno = 0;
|
|
info->si_code = SI_USER;
|
|
info->si_pid = 0;
|
|
info->si_uid = 0;
|
|
}
|
|
}
|
|
|
|
static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
|
|
siginfo_t *info)
|
|
{
|
|
int sig = next_signal(pending, mask);
|
|
|
|
if (sig) {
|
|
if (current->notifier) {
|
|
if (sigismember(current->notifier_mask, sig)) {
|
|
if (!(current->notifier)(current->notifier_data)) {
|
|
clear_thread_flag(TIF_SIGPENDING);
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
collect_signal(sig, pending, info);
|
|
}
|
|
|
|
return sig;
|
|
}
|
|
|
|
/*
|
|
* Dequeue a signal and return the element to the caller, which is
|
|
* expected to free it.
|
|
*
|
|
* All callers have to hold the siglock.
|
|
*/
|
|
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
|
|
{
|
|
int signr;
|
|
|
|
/* We only dequeue private signals from ourselves, we don't let
|
|
* signalfd steal them
|
|
*/
|
|
signr = __dequeue_signal(&tsk->pending, mask, info);
|
|
if (!signr) {
|
|
signr = __dequeue_signal(&tsk->signal->shared_pending,
|
|
mask, info);
|
|
/*
|
|
* itimer signal ?
|
|
*
|
|
* itimers are process shared and we restart periodic
|
|
* itimers in the signal delivery path to prevent DoS
|
|
* attacks in the high resolution timer case. This is
|
|
* compliant with the old way of self-restarting
|
|
* itimers, as the SIGALRM is a legacy signal and only
|
|
* queued once. Changing the restart behaviour to
|
|
* restart the timer in the signal dequeue path is
|
|
* reducing the timer noise on heavy loaded !highres
|
|
* systems too.
|
|
*/
|
|
if (unlikely(signr == SIGALRM)) {
|
|
struct hrtimer *tmr = &tsk->signal->real_timer;
|
|
|
|
if (!hrtimer_is_queued(tmr) &&
|
|
tsk->signal->it_real_incr.tv64 != 0) {
|
|
hrtimer_forward(tmr, tmr->base->get_time(),
|
|
tsk->signal->it_real_incr);
|
|
hrtimer_restart(tmr);
|
|
}
|
|
}
|
|
}
|
|
|
|
recalc_sigpending();
|
|
if (!signr)
|
|
return 0;
|
|
|
|
if (unlikely(sig_kernel_stop(signr))) {
|
|
/*
|
|
* Set a marker that we have dequeued a stop signal. Our
|
|
* caller might release the siglock and then the pending
|
|
* stop signal it is about to process is no longer in the
|
|
* pending bitmasks, but must still be cleared by a SIGCONT
|
|
* (and overruled by a SIGKILL). So those cases clear this
|
|
* shared flag after we've set it. Note that this flag may
|
|
* remain set after the signal we return is ignored or
|
|
* handled. That doesn't matter because its only purpose
|
|
* is to alert stop-signal processing code when another
|
|
* processor has come along and cleared the flag.
|
|
*/
|
|
current->jobctl |= JOBCTL_STOP_DEQUEUED;
|
|
}
|
|
if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
|
|
/*
|
|
* Release the siglock to ensure proper locking order
|
|
* of timer locks outside of siglocks. Note, we leave
|
|
* irqs disabled here, since the posix-timers code is
|
|
* about to disable them again anyway.
|
|
*/
|
|
spin_unlock(&tsk->sighand->siglock);
|
|
do_schedule_next_timer(info);
|
|
spin_lock(&tsk->sighand->siglock);
|
|
}
|
|
return signr;
|
|
}
|
|
|
|
/*
|
|
* Tell a process that it has a new active signal..
|
|
*
|
|
* NOTE! we rely on the previous spin_lock to
|
|
* lock interrupts for us! We can only be called with
|
|
* "siglock" held, and the local interrupt must
|
|
* have been disabled when that got acquired!
|
|
*
|
|
* No need to set need_resched since signal event passing
|
|
* goes through ->blocked
|
|
*/
|
|
void signal_wake_up(struct task_struct *t, int resume)
|
|
{
|
|
unsigned int mask;
|
|
|
|
set_tsk_thread_flag(t, TIF_SIGPENDING);
|
|
|
|
/*
|
|
* For SIGKILL, we want to wake it up in the stopped/traced/killable
|
|
* case. We don't check t->state here because there is a race with it
|
|
* executing another processor and just now entering stopped state.
|
|
* By using wake_up_state, we ensure the process will wake up and
|
|
* handle its death signal.
|
|
*/
|
|
mask = TASK_INTERRUPTIBLE;
|
|
if (resume)
|
|
mask |= TASK_WAKEKILL;
|
|
if (!wake_up_state(t, mask))
|
|
kick_process(t);
|
|
}
|
|
|
|
/*
|
|
* Remove signals in mask from the pending set and queue.
|
|
* Returns 1 if any signals were found.
|
|
*
|
|
* All callers must be holding the siglock.
|
|
*
|
|
* This version takes a sigset mask and looks at all signals,
|
|
* not just those in the first mask word.
|
|
*/
|
|
static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
|
|
{
|
|
struct sigqueue *q, *n;
|
|
sigset_t m;
|
|
|
|
sigandsets(&m, mask, &s->signal);
|
|
if (sigisemptyset(&m))
|
|
return 0;
|
|
|
|
sigandnsets(&s->signal, &s->signal, mask);
|
|
list_for_each_entry_safe(q, n, &s->list, list) {
|
|
if (sigismember(mask, q->info.si_signo)) {
|
|
list_del_init(&q->list);
|
|
__sigqueue_free(q);
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
/*
|
|
* Remove signals in mask from the pending set and queue.
|
|
* Returns 1 if any signals were found.
|
|
*
|
|
* All callers must be holding the siglock.
|
|
*/
|
|
static int rm_from_queue(unsigned long mask, struct sigpending *s)
|
|
{
|
|
struct sigqueue *q, *n;
|
|
|
|
if (!sigtestsetmask(&s->signal, mask))
|
|
return 0;
|
|
|
|
sigdelsetmask(&s->signal, mask);
|
|
list_for_each_entry_safe(q, n, &s->list, list) {
|
|
if (q->info.si_signo < SIGRTMIN &&
|
|
(mask & sigmask(q->info.si_signo))) {
|
|
list_del_init(&q->list);
|
|
__sigqueue_free(q);
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static inline int is_si_special(const struct siginfo *info)
|
|
{
|
|
return info <= SEND_SIG_FORCED;
|
|
}
|
|
|
|
static inline bool si_fromuser(const struct siginfo *info)
|
|
{
|
|
return info == SEND_SIG_NOINFO ||
|
|
(!is_si_special(info) && SI_FROMUSER(info));
|
|
}
|
|
|
|
/*
|
|
* called with RCU read lock from check_kill_permission()
|
|
*/
|
|
static int kill_ok_by_cred(struct task_struct *t)
|
|
{
|
|
const struct cred *cred = current_cred();
|
|
const struct cred *tcred = __task_cred(t);
|
|
|
|
if (uid_eq(cred->euid, tcred->suid) ||
|
|
uid_eq(cred->euid, tcred->uid) ||
|
|
uid_eq(cred->uid, tcred->suid) ||
|
|
uid_eq(cred->uid, tcred->uid))
|
|
return 1;
|
|
|
|
if (ns_capable(tcred->user_ns, CAP_KILL))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Bad permissions for sending the signal
|
|
* - the caller must hold the RCU read lock
|
|
*/
|
|
static int check_kill_permission(int sig, struct siginfo *info,
|
|
struct task_struct *t)
|
|
{
|
|
struct pid *sid;
|
|
int error;
|
|
|
|
if (!valid_signal(sig))
|
|
return -EINVAL;
|
|
|
|
if (!si_fromuser(info))
|
|
return 0;
|
|
|
|
error = audit_signal_info(sig, t); /* Let audit system see the signal */
|
|
if (error)
|
|
return error;
|
|
|
|
if (!same_thread_group(current, t) &&
|
|
!kill_ok_by_cred(t)) {
|
|
switch (sig) {
|
|
case SIGCONT:
|
|
sid = task_session(t);
|
|
/*
|
|
* We don't return the error if sid == NULL. The
|
|
* task was unhashed, the caller must notice this.
|
|
*/
|
|
if (!sid || sid == task_session(current))
|
|
break;
|
|
default:
|
|
return -EPERM;
|
|
}
|
|
}
|
|
|
|
return security_task_kill(t, info, sig, 0);
|
|
}
|
|
|
|
/**
|
|
* ptrace_trap_notify - schedule trap to notify ptracer
|
|
* @t: tracee wanting to notify tracer
|
|
*
|
|
* This function schedules sticky ptrace trap which is cleared on the next
|
|
* TRAP_STOP to notify ptracer of an event. @t must have been seized by
|
|
* ptracer.
|
|
*
|
|
* If @t is running, STOP trap will be taken. If trapped for STOP and
|
|
* ptracer is listening for events, tracee is woken up so that it can
|
|
* re-trap for the new event. If trapped otherwise, STOP trap will be
|
|
* eventually taken without returning to userland after the existing traps
|
|
* are finished by PTRACE_CONT.
|
|
*
|
|
* CONTEXT:
|
|
* Must be called with @task->sighand->siglock held.
|
|
*/
|
|
static void ptrace_trap_notify(struct task_struct *t)
|
|
{
|
|
WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
|
|
assert_spin_locked(&t->sighand->siglock);
|
|
|
|
task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
|
|
signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
|
|
}
|
|
|
|
/*
|
|
* Handle magic process-wide effects of stop/continue signals. Unlike
|
|
* the signal actions, these happen immediately at signal-generation
|
|
* time regardless of blocking, ignoring, or handling. This does the
|
|
* actual continuing for SIGCONT, but not the actual stopping for stop
|
|
* signals. The process stop is done as a signal action for SIG_DFL.
|
|
*
|
|
* Returns true if the signal should be actually delivered, otherwise
|
|
* it should be dropped.
|
|
*/
|
|
static int prepare_signal(int sig, struct task_struct *p, bool force)
|
|
{
|
|
struct signal_struct *signal = p->signal;
|
|
struct task_struct *t;
|
|
|
|
if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
|
|
/*
|
|
* The process is in the middle of dying, nothing to do.
|
|
*/
|
|
} else if (sig_kernel_stop(sig)) {
|
|
/*
|
|
* This is a stop signal. Remove SIGCONT from all queues.
|
|
*/
|
|
rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
|
|
t = p;
|
|
do {
|
|
rm_from_queue(sigmask(SIGCONT), &t->pending);
|
|
} while_each_thread(p, t);
|
|
} else if (sig == SIGCONT) {
|
|
unsigned int why;
|
|
/*
|
|
* Remove all stop signals from all queues, wake all threads.
|
|
*/
|
|
rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
|
|
t = p;
|
|
do {
|
|
task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
|
|
rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
|
|
if (likely(!(t->ptrace & PT_SEIZED)))
|
|
wake_up_state(t, __TASK_STOPPED);
|
|
else
|
|
ptrace_trap_notify(t);
|
|
} while_each_thread(p, t);
|
|
|
|
/*
|
|
* Notify the parent with CLD_CONTINUED if we were stopped.
|
|
*
|
|
* If we were in the middle of a group stop, we pretend it
|
|
* was already finished, and then continued. Since SIGCHLD
|
|
* doesn't queue we report only CLD_STOPPED, as if the next
|
|
* CLD_CONTINUED was dropped.
|
|
*/
|
|
why = 0;
|
|
if (signal->flags & SIGNAL_STOP_STOPPED)
|
|
why |= SIGNAL_CLD_CONTINUED;
|
|
else if (signal->group_stop_count)
|
|
why |= SIGNAL_CLD_STOPPED;
|
|
|
|
if (why) {
|
|
/*
|
|
* The first thread which returns from do_signal_stop()
|
|
* will take ->siglock, notice SIGNAL_CLD_MASK, and
|
|
* notify its parent. See get_signal_to_deliver().
|
|
*/
|
|
signal->flags = why | SIGNAL_STOP_CONTINUED;
|
|
signal->group_stop_count = 0;
|
|
signal->group_exit_code = 0;
|
|
}
|
|
}
|
|
|
|
return !sig_ignored(p, sig, force);
|
|
}
|
|
|
|
/*
|
|
* Test if P wants to take SIG. After we've checked all threads with this,
|
|
* it's equivalent to finding no threads not blocking SIG. Any threads not
|
|
* blocking SIG were ruled out because they are not running and already
|
|
* have pending signals. Such threads will dequeue from the shared queue
|
|
* as soon as they're available, so putting the signal on the shared queue
|
|
* will be equivalent to sending it to one such thread.
|
|
*/
|
|
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 (task_is_stopped_or_traced(p))
|
|
return 0;
|
|
return task_curr(p) || !signal_pending(p);
|
|
}
|
|
|
|
static void complete_signal(int sig, struct task_struct *p, int group)
|
|
{
|
|
struct signal_struct *signal = p->signal;
|
|
struct task_struct *t;
|
|
|
|
/*
|
|
* 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))
|
|
t = p;
|
|
else if (!group || thread_group_empty(p))
|
|
/*
|
|
* There is just one thread and it does not need to be woken.
|
|
* It will dequeue unblocked signals before it runs again.
|
|
*/
|
|
return;
|
|
else {
|
|
/*
|
|
* Otherwise try to find a suitable thread.
|
|
*/
|
|
t = signal->curr_target;
|
|
while (!wants_signal(sig, t)) {
|
|
t = next_thread(t);
|
|
if (t == signal->curr_target)
|
|
/*
|
|
* No thread needs to be woken.
|
|
* Any eligible threads will see
|
|
* the signal in the queue soon.
|
|
*/
|
|
return;
|
|
}
|
|
signal->curr_target = t;
|
|
}
|
|
|
|
/*
|
|
* Found a killable thread. If the signal will be fatal,
|
|
* then start taking the whole group down immediately.
|
|
*/
|
|
if (sig_fatal(p, sig) &&
|
|
!(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
|
|
!sigismember(&t->real_blocked, sig) &&
|
|
(sig == SIGKILL || !t->ptrace)) {
|
|
/*
|
|
* This signal will be fatal to the whole group.
|
|
*/
|
|
if (!sig_kernel_coredump(sig)) {
|
|
/*
|
|
* Start a group exit and wake everybody up.
|
|
* This way we don't have other threads
|
|
* running and doing things after a slower
|
|
* thread has the fatal signal pending.
|
|
*/
|
|
signal->flags = SIGNAL_GROUP_EXIT;
|
|
signal->group_exit_code = sig;
|
|
signal->group_stop_count = 0;
|
|
t = p;
|
|
do {
|
|
task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
|
|
sigaddset(&t->pending.signal, SIGKILL);
|
|
signal_wake_up(t, 1);
|
|
} while_each_thread(p, t);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The signal is already in the shared-pending queue.
|
|
* Tell the chosen thread to wake up and dequeue it.
|
|
*/
|
|
signal_wake_up(t, sig == SIGKILL);
|
|
return;
|
|
}
|
|
|
|
static inline int legacy_queue(struct sigpending *signals, int sig)
|
|
{
|
|
return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
|
|
}
|
|
|
|
#ifdef CONFIG_USER_NS
|
|
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
|
|
{
|
|
if (current_user_ns() == task_cred_xxx(t, user_ns))
|
|
return;
|
|
|
|
if (SI_FROMKERNEL(info))
|
|
return;
|
|
|
|
rcu_read_lock();
|
|
info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
|
|
make_kuid(current_user_ns(), info->si_uid));
|
|
rcu_read_unlock();
|
|
}
|
|
#else
|
|
static inline void userns_fixup_signal_uid(struct siginfo *info, struct task_struct *t)
|
|
{
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
|
|
int group, int from_ancestor_ns)
|
|
{
|
|
struct sigpending *pending;
|
|
struct sigqueue *q;
|
|
int override_rlimit;
|
|
int ret = 0, result;
|
|
|
|
assert_spin_locked(&t->sighand->siglock);
|
|
|
|
result = TRACE_SIGNAL_IGNORED;
|
|
if (!prepare_signal(sig, t,
|
|
from_ancestor_ns || (info == SEND_SIG_FORCED)))
|
|
goto ret;
|
|
|
|
pending = group ? &t->signal->shared_pending : &t->pending;
|
|
/*
|
|
* Short-circuit ignored signals and support queuing
|
|
* exactly one non-rt signal, so that we can get more
|
|
* detailed information about the cause of the signal.
|
|
*/
|
|
result = TRACE_SIGNAL_ALREADY_PENDING;
|
|
if (legacy_queue(pending, sig))
|
|
goto ret;
|
|
|
|
result = TRACE_SIGNAL_DELIVERED;
|
|
/*
|
|
* fast-pathed signals for kernel-internal things like SIGSTOP
|
|
* or SIGKILL.
|
|
*/
|
|
if (info == SEND_SIG_FORCED)
|
|
goto out_set;
|
|
|
|
/*
|
|
* Real-time signals must be queued if sent by sigqueue, or
|
|
* some other real-time mechanism. It is implementation
|
|
* defined whether kill() does so. We attempt to do so, on
|
|
* the principle of least surprise, but since kill is not
|
|
* allowed to fail with EAGAIN when low on memory we just
|
|
* make sure at least one signal gets delivered and don't
|
|
* pass on the info struct.
|
|
*/
|
|
if (sig < SIGRTMIN)
|
|
override_rlimit = (is_si_special(info) || info->si_code >= 0);
|
|
else
|
|
override_rlimit = 0;
|
|
|
|
q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
|
|
override_rlimit);
|
|
if (q) {
|
|
list_add_tail(&q->list, &pending->list);
|
|
switch ((unsigned long) info) {
|
|
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 = task_tgid_nr_ns(current,
|
|
task_active_pid_ns(t));
|
|
q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
|
|
break;
|
|
case (unsigned long) SEND_SIG_PRIV:
|
|
q->info.si_signo = sig;
|
|
q->info.si_errno = 0;
|
|
q->info.si_code = SI_KERNEL;
|
|
q->info.si_pid = 0;
|
|
q->info.si_uid = 0;
|
|
break;
|
|
default:
|
|
copy_siginfo(&q->info, info);
|
|
if (from_ancestor_ns)
|
|
q->info.si_pid = 0;
|
|
break;
|
|
}
|
|
|
|
userns_fixup_signal_uid(&q->info, t);
|
|
|
|
} 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().
|
|
*/
|
|
result = TRACE_SIGNAL_OVERFLOW_FAIL;
|
|
ret = -EAGAIN;
|
|
goto ret;
|
|
} else {
|
|
/*
|
|
* This is a silent loss of information. We still
|
|
* send the signal, but the *info bits are lost.
|
|
*/
|
|
result = TRACE_SIGNAL_LOSE_INFO;
|
|
}
|
|
}
|
|
|
|
out_set:
|
|
signalfd_notify(t, sig);
|
|
sigaddset(&pending->signal, sig);
|
|
complete_signal(sig, t, group);
|
|
ret:
|
|
trace_signal_generate(sig, info, t, group, result);
|
|
return ret;
|
|
}
|
|
|
|
static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
|
|
int group)
|
|
{
|
|
int from_ancestor_ns = 0;
|
|
|
|
#ifdef CONFIG_PID_NS
|
|
from_ancestor_ns = si_fromuser(info) &&
|
|
!task_pid_nr_ns(current, task_active_pid_ns(t));
|
|
#endif
|
|
|
|
return __send_signal(sig, info, t, group, from_ancestor_ns);
|
|
}
|
|
|
|
static void print_fatal_signal(struct pt_regs *regs, int signr)
|
|
{
|
|
printk("%s/%d: potentially unexpected fatal signal %d.\n",
|
|
current->comm, task_pid_nr(current), signr);
|
|
|
|
#if defined(__i386__) && !defined(__arch_um__)
|
|
printk("code at %08lx: ", regs->ip);
|
|
{
|
|
int i;
|
|
for (i = 0; i < 16; i++) {
|
|
unsigned char insn;
|
|
|
|
if (get_user(insn, (unsigned char *)(regs->ip + i)))
|
|
break;
|
|
printk("%02x ", insn);
|
|
}
|
|
}
|
|
#endif
|
|
printk("\n");
|
|
preempt_disable();
|
|
show_regs(regs);
|
|
preempt_enable();
|
|
}
|
|
|
|
static int __init setup_print_fatal_signals(char *str)
|
|
{
|
|
get_option (&str, &print_fatal_signals);
|
|
|
|
return 1;
|
|
}
|
|
|
|
__setup("print-fatal-signals=", setup_print_fatal_signals);
|
|
|
|
int
|
|
__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
|
|
{
|
|
return send_signal(sig, info, p, 1);
|
|
}
|
|
|
|
static int
|
|
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
|
|
{
|
|
return send_signal(sig, info, t, 0);
|
|
}
|
|
|
|
int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
|
|
bool group)
|
|
{
|
|
unsigned long flags;
|
|
int ret = -ESRCH;
|
|
|
|
if (lock_task_sighand(p, &flags)) {
|
|
ret = send_signal(sig, info, p, group);
|
|
unlock_task_sighand(p, &flags);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Force a signal that the process can't ignore: if necessary
|
|
* we unblock the signal and change any SIG_IGN to SIG_DFL.
|
|
*
|
|
* Note: If we unblock the signal, we always reset it to SIG_DFL,
|
|
* since we do not want to have a signal handler that was blocked
|
|
* be invoked when user space had explicitly blocked it.
|
|
*
|
|
* We don't want to have recursive SIGSEGV's etc, for example,
|
|
* that is why we also clear SIGNAL_UNKILLABLE.
|
|
*/
|
|
int
|
|
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
|
|
{
|
|
unsigned long int flags;
|
|
int ret, blocked, ignored;
|
|
struct k_sigaction *action;
|
|
|
|
spin_lock_irqsave(&t->sighand->siglock, flags);
|
|
action = &t->sighand->action[sig-1];
|
|
ignored = action->sa.sa_handler == SIG_IGN;
|
|
blocked = sigismember(&t->blocked, sig);
|
|
if (blocked || ignored) {
|
|
action->sa.sa_handler = SIG_DFL;
|
|
if (blocked) {
|
|
sigdelset(&t->blocked, sig);
|
|
recalc_sigpending_and_wake(t);
|
|
}
|
|
}
|
|
if (action->sa.sa_handler == SIG_DFL)
|
|
t->signal->flags &= ~SIGNAL_UNKILLABLE;
|
|
ret = specific_send_sig_info(sig, info, t);
|
|
spin_unlock_irqrestore(&t->sighand->siglock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Nuke all other threads in the group.
|
|
*/
|
|
int zap_other_threads(struct task_struct *p)
|
|
{
|
|
struct task_struct *t = p;
|
|
int count = 0;
|
|
|
|
p->signal->group_stop_count = 0;
|
|
|
|
while_each_thread(p, t) {
|
|
task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
|
|
count++;
|
|
|
|
/* Don't bother with already dead threads */
|
|
if (t->exit_state)
|
|
continue;
|
|
sigaddset(&t->pending.signal, SIGKILL);
|
|
signal_wake_up(t, 1);
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
|
|
unsigned long *flags)
|
|
{
|
|
struct sighand_struct *sighand;
|
|
|
|
for (;;) {
|
|
local_irq_save(*flags);
|
|
rcu_read_lock();
|
|
sighand = rcu_dereference(tsk->sighand);
|
|
if (unlikely(sighand == NULL)) {
|
|
rcu_read_unlock();
|
|
local_irq_restore(*flags);
|
|
break;
|
|
}
|
|
|
|
spin_lock(&sighand->siglock);
|
|
if (likely(sighand == tsk->sighand)) {
|
|
rcu_read_unlock();
|
|
break;
|
|
}
|
|
spin_unlock(&sighand->siglock);
|
|
rcu_read_unlock();
|
|
local_irq_restore(*flags);
|
|
}
|
|
|
|
return sighand;
|
|
}
|
|
|
|
/*
|
|
* send signal info to all the members of a group
|
|
*/
|
|
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
|
|
{
|
|
int ret;
|
|
|
|
rcu_read_lock();
|
|
ret = check_kill_permission(sig, info, p);
|
|
rcu_read_unlock();
|
|
|
|
if (!ret && sig)
|
|
ret = do_send_sig_info(sig, info, p, true);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* __kill_pgrp_info() sends a signal to a process group: this is what the tty
|
|
* control characters do (^C, ^Z etc)
|
|
* - the caller must hold at least a readlock on tasklist_lock
|
|
*/
|
|
int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
|
|
{
|
|
struct task_struct *p = NULL;
|
|
int retval, success;
|
|
|
|
success = 0;
|
|
retval = -ESRCH;
|
|
do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
|
|
int err = group_send_sig_info(sig, info, p);
|
|
success |= !err;
|
|
retval = err;
|
|
} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
|
|
return success ? 0 : retval;
|
|
}
|
|
|
|
int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
|
|
{
|
|
int error = -ESRCH;
|
|
struct task_struct *p;
|
|
|
|
rcu_read_lock();
|
|
retry:
|
|
p = pid_task(pid, PIDTYPE_PID);
|
|
if (p) {
|
|
error = group_send_sig_info(sig, info, p);
|
|
if (unlikely(error == -ESRCH))
|
|
/*
|
|
* The task was unhashed in between, try again.
|
|
* If it is dead, pid_task() will return NULL,
|
|
* if we race with de_thread() it will find the
|
|
* new leader.
|
|
*/
|
|
goto retry;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return error;
|
|
}
|
|
|
|
int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
|
|
{
|
|
int error;
|
|
rcu_read_lock();
|
|
error = kill_pid_info(sig, info, find_vpid(pid));
|
|
rcu_read_unlock();
|
|
return error;
|
|
}
|
|
|
|
static int kill_as_cred_perm(const struct cred *cred,
|
|
struct task_struct *target)
|
|
{
|
|
const struct cred *pcred = __task_cred(target);
|
|
if (!uid_eq(cred->euid, pcred->suid) && !uid_eq(cred->euid, pcred->uid) &&
|
|
!uid_eq(cred->uid, pcred->suid) && !uid_eq(cred->uid, pcred->uid))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/* like kill_pid_info(), but doesn't use uid/euid of "current" */
|
|
int kill_pid_info_as_cred(int sig, struct siginfo *info, struct pid *pid,
|
|
const struct cred *cred, u32 secid)
|
|
{
|
|
int ret = -EINVAL;
|
|
struct task_struct *p;
|
|
unsigned long flags;
|
|
|
|
if (!valid_signal(sig))
|
|
return ret;
|
|
|
|
rcu_read_lock();
|
|
p = pid_task(pid, PIDTYPE_PID);
|
|
if (!p) {
|
|
ret = -ESRCH;
|
|
goto out_unlock;
|
|
}
|
|
if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
|
|
ret = -EPERM;
|
|
goto out_unlock;
|
|
}
|
|
ret = security_task_kill(p, info, sig, secid);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
if (sig) {
|
|
if (lock_task_sighand(p, &flags)) {
|
|
ret = __send_signal(sig, info, p, 1, 0);
|
|
unlock_task_sighand(p, &flags);
|
|
} else
|
|
ret = -ESRCH;
|
|
}
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
|
|
|
|
/*
|
|
* kill_something_info() interprets pid in interesting ways just like kill(2).
|
|
*
|
|
* POSIX specifies that kill(-1,sig) is unspecified, but what we have
|
|
* is probably wrong. Should make it like BSD or SYSV.
|
|
*/
|
|
|
|
static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
|
|
{
|
|
int ret;
|
|
|
|
if (pid > 0) {
|
|
rcu_read_lock();
|
|
ret = kill_pid_info(sig, info, find_vpid(pid));
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
read_lock(&tasklist_lock);
|
|
if (pid != -1) {
|
|
ret = __kill_pgrp_info(sig, info,
|
|
pid ? find_vpid(-pid) : task_pgrp(current));
|
|
} else {
|
|
int retval = 0, count = 0;
|
|
struct task_struct * p;
|
|
|
|
for_each_process(p) {
|
|
if (task_pid_vnr(p) > 1 &&
|
|
!same_thread_group(p, current)) {
|
|
int err = group_send_sig_info(sig, info, p);
|
|
++count;
|
|
if (err != -EPERM)
|
|
retval = err;
|
|
}
|
|
}
|
|
ret = count ? retval : -ESRCH;
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* These are for backward compatibility with the rest of the kernel source.
|
|
*/
|
|
|
|
int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
|
|
{
|
|
/*
|
|
* Make sure legacy kernel users don't send in bad values
|
|
* (normal paths check this in check_kill_permission).
|
|
*/
|
|
if (!valid_signal(sig))
|
|
return -EINVAL;
|
|
|
|
return do_send_sig_info(sig, info, p, false);
|
|
}
|
|
|
|
#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, __si_special(priv), p);
|
|
}
|
|
|
|
void
|
|
force_sig(int sig, struct task_struct *p)
|
|
{
|
|
force_sig_info(sig, SEND_SIG_PRIV, p);
|
|
}
|
|
|
|
/*
|
|
* When things go south during signal handling, we
|
|
* will force a SIGSEGV. And if the signal that caused
|
|
* the problem was already a SIGSEGV, we'll want to
|
|
* make sure we don't even try to deliver the signal..
|
|
*/
|
|
int
|
|
force_sigsegv(int sig, struct task_struct *p)
|
|
{
|
|
if (sig == SIGSEGV) {
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&p->sighand->siglock, flags);
|
|
p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
|
|
spin_unlock_irqrestore(&p->sighand->siglock, flags);
|
|
}
|
|
force_sig(SIGSEGV, p);
|
|
return 0;
|
|
}
|
|
|
|
int kill_pgrp(struct pid *pid, int sig, int priv)
|
|
{
|
|
int ret;
|
|
|
|
read_lock(&tasklist_lock);
|
|
ret = __kill_pgrp_info(sig, __si_special(priv), pid);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(kill_pgrp);
|
|
|
|
int kill_pid(struct pid *pid, int sig, int priv)
|
|
{
|
|
return kill_pid_info(sig, __si_special(priv), pid);
|
|
}
|
|
EXPORT_SYMBOL(kill_pid);
|
|
|
|
/*
|
|
* These functions support sending signals using preallocated sigqueue
|
|
* structures. This is needed "because realtime applications cannot
|
|
* afford to lose notifications of asynchronous events, like timer
|
|
* expirations or I/O completions". In the case of POSIX Timers
|
|
* we allocate the sigqueue structure from the timer_create. If this
|
|
* allocation fails we are able to report the failure to the application
|
|
* with an EAGAIN error.
|
|
*/
|
|
struct sigqueue *sigqueue_alloc(void)
|
|
{
|
|
struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
|
|
|
|
if (q)
|
|
q->flags |= SIGQUEUE_PREALLOC;
|
|
|
|
return q;
|
|
}
|
|
|
|
void sigqueue_free(struct sigqueue *q)
|
|
{
|
|
unsigned long flags;
|
|
spinlock_t *lock = ¤t->sighand->siglock;
|
|
|
|
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
|
|
/*
|
|
* We must hold ->siglock while testing q->list
|
|
* to serialize with collect_signal() or with
|
|
* __exit_signal()->flush_sigqueue().
|
|
*/
|
|
spin_lock_irqsave(lock, flags);
|
|
q->flags &= ~SIGQUEUE_PREALLOC;
|
|
/*
|
|
* If it is queued it will be freed when dequeued,
|
|
* like the "regular" sigqueue.
|
|
*/
|
|
if (!list_empty(&q->list))
|
|
q = NULL;
|
|
spin_unlock_irqrestore(lock, flags);
|
|
|
|
if (q)
|
|
__sigqueue_free(q);
|
|
}
|
|
|
|
int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
|
|
{
|
|
int sig = q->info.si_signo;
|
|
struct sigpending *pending;
|
|
unsigned long flags;
|
|
int ret, result;
|
|
|
|
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
|
|
|
|
ret = -1;
|
|
if (!likely(lock_task_sighand(t, &flags)))
|
|
goto ret;
|
|
|
|
ret = 1; /* the signal is ignored */
|
|
result = TRACE_SIGNAL_IGNORED;
|
|
if (!prepare_signal(sig, t, false))
|
|
goto out;
|
|
|
|
ret = 0;
|
|
if (unlikely(!list_empty(&q->list))) {
|
|
/*
|
|
* If an SI_TIMER entry is already queue just increment
|
|
* the overrun count.
|
|
*/
|
|
BUG_ON(q->info.si_code != SI_TIMER);
|
|
q->info.si_overrun++;
|
|
result = TRACE_SIGNAL_ALREADY_PENDING;
|
|
goto out;
|
|
}
|
|
q->info.si_overrun = 0;
|
|
|
|
signalfd_notify(t, sig);
|
|
pending = group ? &t->signal->shared_pending : &t->pending;
|
|
list_add_tail(&q->list, &pending->list);
|
|
sigaddset(&pending->signal, sig);
|
|
complete_signal(sig, t, group);
|
|
result = TRACE_SIGNAL_DELIVERED;
|
|
out:
|
|
trace_signal_generate(sig, &q->info, t, group, result);
|
|
unlock_task_sighand(t, &flags);
|
|
ret:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Let a parent know about the death of a child.
|
|
* For a stopped/continued status change, use do_notify_parent_cldstop instead.
|
|
*
|
|
* Returns true if our parent ignored us and so we've switched to
|
|
* self-reaping.
|
|
*/
|
|
bool do_notify_parent(struct task_struct *tsk, int sig)
|
|
{
|
|
struct siginfo info;
|
|
unsigned long flags;
|
|
struct sighand_struct *psig;
|
|
bool autoreap = false;
|
|
|
|
BUG_ON(sig == -1);
|
|
|
|
/* do_notify_parent_cldstop should have been called instead. */
|
|
BUG_ON(task_is_stopped_or_traced(tsk));
|
|
|
|
BUG_ON(!tsk->ptrace &&
|
|
(tsk->group_leader != tsk || !thread_group_empty(tsk)));
|
|
|
|
if (sig != SIGCHLD) {
|
|
/*
|
|
* This is only possible if parent == real_parent.
|
|
* Check if it has changed security domain.
|
|
*/
|
|
if (tsk->parent_exec_id != tsk->parent->self_exec_id)
|
|
sig = SIGCHLD;
|
|
}
|
|
|
|
info.si_signo = sig;
|
|
info.si_errno = 0;
|
|
/*
|
|
* we are under tasklist_lock here so our parent is tied to
|
|
* us and cannot exit and release its namespace.
|
|
*
|
|
* the only it can is to switch its nsproxy with sys_unshare,
|
|
* bu uncharing pid namespaces is not allowed, so we'll always
|
|
* see relevant namespace
|
|
*
|
|
* write_lock() currently calls preempt_disable() which is the
|
|
* same as rcu_read_lock(), but according to Oleg, this is not
|
|
* correct to rely on this
|
|
*/
|
|
rcu_read_lock();
|
|
info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
|
|
info.si_uid = from_kuid_munged(task_cred_xxx(tsk->parent, user_ns),
|
|
task_uid(tsk));
|
|
rcu_read_unlock();
|
|
|
|
info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
|
|
info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
|
|
|
|
info.si_status = tsk->exit_code & 0x7f;
|
|
if (tsk->exit_code & 0x80)
|
|
info.si_code = CLD_DUMPED;
|
|
else if (tsk->exit_code & 0x7f)
|
|
info.si_code = CLD_KILLED;
|
|
else {
|
|
info.si_code = CLD_EXITED;
|
|
info.si_status = tsk->exit_code >> 8;
|
|
}
|
|
|
|
psig = tsk->parent->sighand;
|
|
spin_lock_irqsave(&psig->siglock, flags);
|
|
if (!tsk->ptrace && sig == SIGCHLD &&
|
|
(psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
|
|
(psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
|
|
/*
|
|
* We are exiting and our parent doesn't care. POSIX.1
|
|
* defines special semantics for setting SIGCHLD to SIG_IGN
|
|
* or setting the SA_NOCLDWAIT flag: we should be reaped
|
|
* automatically and not left for our parent's wait4 call.
|
|
* Rather than having the parent do it as a magic kind of
|
|
* signal handler, we just set this to tell do_exit that we
|
|
* can be cleaned up without becoming a zombie. Note that
|
|
* we still call __wake_up_parent in this case, because a
|
|
* blocked sys_wait4 might now return -ECHILD.
|
|
*
|
|
* Whether we send SIGCHLD or not for SA_NOCLDWAIT
|
|
* is implementation-defined: we do (if you don't want
|
|
* it, just use SIG_IGN instead).
|
|
*/
|
|
autoreap = true;
|
|
if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
|
|
sig = 0;
|
|
}
|
|
if (valid_signal(sig) && sig)
|
|
__group_send_sig_info(sig, &info, tsk->parent);
|
|
__wake_up_parent(tsk, tsk->parent);
|
|
spin_unlock_irqrestore(&psig->siglock, flags);
|
|
|
|
return autoreap;
|
|
}
|
|
|
|
/**
|
|
* do_notify_parent_cldstop - notify parent of stopped/continued state change
|
|
* @tsk: task reporting the state change
|
|
* @for_ptracer: the notification is for ptracer
|
|
* @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
|
|
*
|
|
* Notify @tsk's parent that the stopped/continued state has changed. If
|
|
* @for_ptracer is %false, @tsk's group leader notifies to its real parent.
|
|
* If %true, @tsk reports to @tsk->parent which should be the ptracer.
|
|
*
|
|
* CONTEXT:
|
|
* Must be called with tasklist_lock at least read locked.
|
|
*/
|
|
static void do_notify_parent_cldstop(struct task_struct *tsk,
|
|
bool for_ptracer, int why)
|
|
{
|
|
struct siginfo info;
|
|
unsigned long flags;
|
|
struct task_struct *parent;
|
|
struct sighand_struct *sighand;
|
|
|
|
if (for_ptracer) {
|
|
parent = tsk->parent;
|
|
} else {
|
|
tsk = tsk->group_leader;
|
|
parent = tsk->real_parent;
|
|
}
|
|
|
|
info.si_signo = SIGCHLD;
|
|
info.si_errno = 0;
|
|
/*
|
|
* see comment in do_notify_parent() about the following 4 lines
|
|
*/
|
|
rcu_read_lock();
|
|
info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
|
|
info.si_uid = from_kuid_munged(task_cred_xxx(parent, user_ns), task_uid(tsk));
|
|
rcu_read_unlock();
|
|
|
|
info.si_utime = cputime_to_clock_t(tsk->utime);
|
|
info.si_stime = cputime_to_clock_t(tsk->stime);
|
|
|
|
info.si_code = why;
|
|
switch (why) {
|
|
case CLD_CONTINUED:
|
|
info.si_status = SIGCONT;
|
|
break;
|
|
case CLD_STOPPED:
|
|
info.si_status = tsk->signal->group_exit_code & 0x7f;
|
|
break;
|
|
case CLD_TRAPPED:
|
|
info.si_status = tsk->exit_code & 0x7f;
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
sighand = parent->sighand;
|
|
spin_lock_irqsave(&sighand->siglock, flags);
|
|
if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
|
|
!(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
|
|
__group_send_sig_info(SIGCHLD, &info, parent);
|
|
/*
|
|
* Even if SIGCHLD is not generated, we must wake up wait4 calls.
|
|
*/
|
|
__wake_up_parent(tsk, parent);
|
|
spin_unlock_irqrestore(&sighand->siglock, flags);
|
|
}
|
|
|
|
static inline int may_ptrace_stop(void)
|
|
{
|
|
if (!likely(current->ptrace))
|
|
return 0;
|
|
/*
|
|
* Are we in the middle of do_coredump?
|
|
* If so and our tracer is also part of the coredump stopping
|
|
* is a deadlock situation, and pointless because our tracer
|
|
* is dead so don't allow us to stop.
|
|
* If SIGKILL was already sent before the caller unlocked
|
|
* ->siglock we must see ->core_state != NULL. Otherwise it
|
|
* is safe to enter schedule().
|
|
*/
|
|
if (unlikely(current->mm->core_state) &&
|
|
unlikely(current->mm == current->parent->mm))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Return non-zero if there is a SIGKILL that should be waking us up.
|
|
* Called with the siglock held.
|
|
*/
|
|
static int sigkill_pending(struct task_struct *tsk)
|
|
{
|
|
return sigismember(&tsk->pending.signal, SIGKILL) ||
|
|
sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
|
|
}
|
|
|
|
/*
|
|
* This must be called with current->sighand->siglock held.
|
|
*
|
|
* This should be the path for all ptrace stops.
|
|
* We always set current->last_siginfo while stopped here.
|
|
* That makes it a way to test a stopped process for
|
|
* being ptrace-stopped vs being job-control-stopped.
|
|
*
|
|
* If we actually decide not to stop at all because the tracer
|
|
* is gone, we keep current->exit_code unless clear_code.
|
|
*/
|
|
static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
|
|
__releases(¤t->sighand->siglock)
|
|
__acquires(¤t->sighand->siglock)
|
|
{
|
|
bool gstop_done = false;
|
|
|
|
if (arch_ptrace_stop_needed(exit_code, info)) {
|
|
/*
|
|
* The arch code has something special to do before a
|
|
* ptrace stop. This is allowed to block, e.g. for faults
|
|
* on user stack pages. We can't keep the siglock while
|
|
* calling arch_ptrace_stop, so we must release it now.
|
|
* To preserve proper semantics, we must do this before
|
|
* any signal bookkeeping like checking group_stop_count.
|
|
* Meanwhile, a SIGKILL could come in before we retake the
|
|
* siglock. That must prevent us from sleeping in TASK_TRACED.
|
|
* So after regaining the lock, we must check for SIGKILL.
|
|
*/
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
arch_ptrace_stop(exit_code, info);
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
if (sigkill_pending(current))
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We're committing to trapping. TRACED should be visible before
|
|
* TRAPPING is cleared; otherwise, the tracer might fail do_wait().
|
|
* Also, transition to TRACED and updates to ->jobctl should be
|
|
* atomic with respect to siglock and should be done after the arch
|
|
* hook as siglock is released and regrabbed across it.
|
|
*/
|
|
set_current_state(TASK_TRACED);
|
|
|
|
current->last_siginfo = info;
|
|
current->exit_code = exit_code;
|
|
|
|
/*
|
|
* If @why is CLD_STOPPED, we're trapping to participate in a group
|
|
* stop. Do the bookkeeping. Note that if SIGCONT was delievered
|
|
* across siglock relocks since INTERRUPT was scheduled, PENDING
|
|
* could be clear now. We act as if SIGCONT is received after
|
|
* TASK_TRACED is entered - ignore it.
|
|
*/
|
|
if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
|
|
gstop_done = task_participate_group_stop(current);
|
|
|
|
/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
|
|
task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
|
|
if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
|
|
task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
|
|
|
|
/* entering a trap, clear TRAPPING */
|
|
task_clear_jobctl_trapping(current);
|
|
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
read_lock(&tasklist_lock);
|
|
if (may_ptrace_stop()) {
|
|
/*
|
|
* Notify parents of the stop.
|
|
*
|
|
* While ptraced, there are two parents - the ptracer and
|
|
* the real_parent of the group_leader. The ptracer should
|
|
* know about every stop while the real parent is only
|
|
* interested in the completion of group stop. The states
|
|
* for the two don't interact with each other. Notify
|
|
* separately unless they're gonna be duplicates.
|
|
*/
|
|
do_notify_parent_cldstop(current, true, why);
|
|
if (gstop_done && ptrace_reparented(current))
|
|
do_notify_parent_cldstop(current, false, why);
|
|
|
|
/*
|
|
* Don't want to allow preemption here, because
|
|
* sys_ptrace() needs this task to be inactive.
|
|
*
|
|
* XXX: implement read_unlock_no_resched().
|
|
*/
|
|
preempt_disable();
|
|
read_unlock(&tasklist_lock);
|
|
preempt_enable_no_resched();
|
|
schedule();
|
|
} else {
|
|
/*
|
|
* By the time we got the lock, our tracer went away.
|
|
* Don't drop the lock yet, another tracer may come.
|
|
*
|
|
* If @gstop_done, the ptracer went away between group stop
|
|
* completion and here. During detach, it would have set
|
|
* JOBCTL_STOP_PENDING on us and we'll re-enter
|
|
* TASK_STOPPED in do_signal_stop() on return, so notifying
|
|
* the real parent of the group stop completion is enough.
|
|
*/
|
|
if (gstop_done)
|
|
do_notify_parent_cldstop(current, false, why);
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
if (clear_code)
|
|
current->exit_code = 0;
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
/*
|
|
* While in TASK_TRACED, we were considered "frozen enough".
|
|
* Now that we woke up, it's crucial if we're supposed to be
|
|
* frozen that we freeze now before running anything substantial.
|
|
*/
|
|
try_to_freeze();
|
|
|
|
/*
|
|
* We are back. Now reacquire the siglock before touching
|
|
* last_siginfo, so that we are sure to have synchronized with
|
|
* any signal-sending on another CPU that wants to examine it.
|
|
*/
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
current->last_siginfo = NULL;
|
|
|
|
/* LISTENING can be set only during STOP traps, clear it */
|
|
current->jobctl &= ~JOBCTL_LISTENING;
|
|
|
|
/*
|
|
* Queued signals ignored us while we were stopped for tracing.
|
|
* So check for any that we should take before resuming user mode.
|
|
* This sets TIF_SIGPENDING, but never clears it.
|
|
*/
|
|
recalc_sigpending_tsk(current);
|
|
}
|
|
|
|
static void ptrace_do_notify(int signr, int exit_code, int why)
|
|
{
|
|
siginfo_t info;
|
|
|
|
memset(&info, 0, sizeof info);
|
|
info.si_signo = signr;
|
|
info.si_code = exit_code;
|
|
info.si_pid = task_pid_vnr(current);
|
|
info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
|
|
|
|
/* Let the debugger run. */
|
|
ptrace_stop(exit_code, why, 1, &info);
|
|
}
|
|
|
|
void ptrace_notify(int exit_code)
|
|
{
|
|
BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
}
|
|
|
|
/**
|
|
* do_signal_stop - handle group stop for SIGSTOP and other stop signals
|
|
* @signr: signr causing group stop if initiating
|
|
*
|
|
* If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
|
|
* and participate in it. If already set, participate in the existing
|
|
* group stop. If participated in a group stop (and thus slept), %true is
|
|
* returned with siglock released.
|
|
*
|
|
* If ptraced, this function doesn't handle stop itself. Instead,
|
|
* %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
|
|
* untouched. The caller must ensure that INTERRUPT trap handling takes
|
|
* places afterwards.
|
|
*
|
|
* CONTEXT:
|
|
* Must be called with @current->sighand->siglock held, which is released
|
|
* on %true return.
|
|
*
|
|
* RETURNS:
|
|
* %false if group stop is already cancelled or ptrace trap is scheduled.
|
|
* %true if participated in group stop.
|
|
*/
|
|
static bool do_signal_stop(int signr)
|
|
__releases(¤t->sighand->siglock)
|
|
{
|
|
struct signal_struct *sig = current->signal;
|
|
|
|
if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
|
|
unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
|
|
struct task_struct *t;
|
|
|
|
/* signr will be recorded in task->jobctl for retries */
|
|
WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
|
|
|
|
if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
|
|
unlikely(signal_group_exit(sig)))
|
|
return false;
|
|
/*
|
|
* There is no group stop already in progress. We must
|
|
* initiate one now.
|
|
*
|
|
* While ptraced, a task may be resumed while group stop is
|
|
* still in effect and then receive a stop signal and
|
|
* initiate another group stop. This deviates from the
|
|
* usual behavior as two consecutive stop signals can't
|
|
* cause two group stops when !ptraced. That is why we
|
|
* also check !task_is_stopped(t) below.
|
|
*
|
|
* The condition can be distinguished by testing whether
|
|
* SIGNAL_STOP_STOPPED is already set. Don't generate
|
|
* group_exit_code in such case.
|
|
*
|
|
* This is not necessary for SIGNAL_STOP_CONTINUED because
|
|
* an intervening stop signal is required to cause two
|
|
* continued events regardless of ptrace.
|
|
*/
|
|
if (!(sig->flags & SIGNAL_STOP_STOPPED))
|
|
sig->group_exit_code = signr;
|
|
|
|
sig->group_stop_count = 0;
|
|
|
|
if (task_set_jobctl_pending(current, signr | gstop))
|
|
sig->group_stop_count++;
|
|
|
|
for (t = next_thread(current); t != current;
|
|
t = next_thread(t)) {
|
|
/*
|
|
* Setting state to TASK_STOPPED for a group
|
|
* stop is always done with the siglock held,
|
|
* so this check has no races.
|
|
*/
|
|
if (!task_is_stopped(t) &&
|
|
task_set_jobctl_pending(t, signr | gstop)) {
|
|
sig->group_stop_count++;
|
|
if (likely(!(t->ptrace & PT_SEIZED)))
|
|
signal_wake_up(t, 0);
|
|
else
|
|
ptrace_trap_notify(t);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (likely(!current->ptrace)) {
|
|
int notify = 0;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (task_participate_group_stop(current))
|
|
notify = CLD_STOPPED;
|
|
|
|
__set_current_state(TASK_STOPPED);
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Notify the parent of the group stop completion. Because
|
|
* we're not holding either the siglock or tasklist_lock
|
|
* here, ptracer may attach inbetween; however, this is for
|
|
* group stop and should always be delivered to the real
|
|
* parent of the group leader. The new ptracer will get
|
|
* its notification when this task transitions into
|
|
* TASK_TRACED.
|
|
*/
|
|
if (notify) {
|
|
read_lock(&tasklist_lock);
|
|
do_notify_parent_cldstop(current, false, notify);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
/* Now we don't run again until woken by SIGCONT or SIGKILL */
|
|
schedule();
|
|
return true;
|
|
} else {
|
|
/*
|
|
* While ptraced, group stop is handled by STOP trap.
|
|
* Schedule it and let the caller deal with it.
|
|
*/
|
|
task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* do_jobctl_trap - take care of ptrace jobctl traps
|
|
*
|
|
* When PT_SEIZED, it's used for both group stop and explicit
|
|
* SEIZE/INTERRUPT traps. Both generate PTRACE_EVENT_STOP trap with
|
|
* accompanying siginfo. If stopped, lower eight bits of exit_code contain
|
|
* the stop signal; otherwise, %SIGTRAP.
|
|
*
|
|
* When !PT_SEIZED, it's used only for group stop trap with stop signal
|
|
* number as exit_code and no siginfo.
|
|
*
|
|
* CONTEXT:
|
|
* Must be called with @current->sighand->siglock held, which may be
|
|
* released and re-acquired before returning with intervening sleep.
|
|
*/
|
|
static void do_jobctl_trap(void)
|
|
{
|
|
struct signal_struct *signal = current->signal;
|
|
int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
|
|
|
|
if (current->ptrace & PT_SEIZED) {
|
|
if (!signal->group_stop_count &&
|
|
!(signal->flags & SIGNAL_STOP_STOPPED))
|
|
signr = SIGTRAP;
|
|
WARN_ON_ONCE(!signr);
|
|
ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
|
|
CLD_STOPPED);
|
|
} else {
|
|
WARN_ON_ONCE(!signr);
|
|
ptrace_stop(signr, CLD_STOPPED, 0, NULL);
|
|
current->exit_code = 0;
|
|
}
|
|
}
|
|
|
|
static int ptrace_signal(int signr, siginfo_t *info,
|
|
struct pt_regs *regs, void *cookie)
|
|
{
|
|
ptrace_signal_deliver(regs, cookie);
|
|
/*
|
|
* We do not check sig_kernel_stop(signr) but set this marker
|
|
* unconditionally because we do not know whether debugger will
|
|
* change signr. This flag has no meaning unless we are going
|
|
* to stop after return from ptrace_stop(). In this case it will
|
|
* be checked in do_signal_stop(), we should only stop if it was
|
|
* not cleared by SIGCONT while we were sleeping. See also the
|
|
* comment in dequeue_signal().
|
|
*/
|
|
current->jobctl |= JOBCTL_STOP_DEQUEUED;
|
|
ptrace_stop(signr, CLD_TRAPPED, 0, info);
|
|
|
|
/* We're back. Did the debugger cancel the sig? */
|
|
signr = current->exit_code;
|
|
if (signr == 0)
|
|
return signr;
|
|
|
|
current->exit_code = 0;
|
|
|
|
/*
|
|
* Update the siginfo structure if the signal has
|
|
* changed. If the debugger wanted something
|
|
* specific in the siginfo structure then it should
|
|
* have updated *info via PTRACE_SETSIGINFO.
|
|
*/
|
|
if (signr != info->si_signo) {
|
|
info->si_signo = signr;
|
|
info->si_errno = 0;
|
|
info->si_code = SI_USER;
|
|
rcu_read_lock();
|
|
info->si_pid = task_pid_vnr(current->parent);
|
|
info->si_uid = from_kuid_munged(current_user_ns(),
|
|
task_uid(current->parent));
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/* If the (new) signal is now blocked, requeue it. */
|
|
if (sigismember(¤t->blocked, signr)) {
|
|
specific_send_sig_info(signr, info, current);
|
|
signr = 0;
|
|
}
|
|
|
|
return signr;
|
|
}
|
|
|
|
int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
|
|
struct pt_regs *regs, void *cookie)
|
|
{
|
|
struct sighand_struct *sighand = current->sighand;
|
|
struct signal_struct *signal = current->signal;
|
|
int signr;
|
|
|
|
relock:
|
|
/*
|
|
* We'll jump back here after any time we were stopped in TASK_STOPPED.
|
|
* While in TASK_STOPPED, we were considered "frozen enough".
|
|
* Now that we woke up, it's crucial if we're supposed to be
|
|
* frozen that we freeze now before running anything substantial.
|
|
*/
|
|
try_to_freeze();
|
|
|
|
spin_lock_irq(&sighand->siglock);
|
|
/*
|
|
* Every stopped thread goes here after wakeup. Check to see if
|
|
* we should notify the parent, prepare_signal(SIGCONT) encodes
|
|
* the CLD_ si_code into SIGNAL_CLD_MASK bits.
|
|
*/
|
|
if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
|
|
int why;
|
|
|
|
if (signal->flags & SIGNAL_CLD_CONTINUED)
|
|
why = CLD_CONTINUED;
|
|
else
|
|
why = CLD_STOPPED;
|
|
|
|
signal->flags &= ~SIGNAL_CLD_MASK;
|
|
|
|
spin_unlock_irq(&sighand->siglock);
|
|
|
|
/*
|
|
* Notify the parent that we're continuing. This event is
|
|
* always per-process and doesn't make whole lot of sense
|
|
* for ptracers, who shouldn't consume the state via
|
|
* wait(2) either, but, for backward compatibility, notify
|
|
* the ptracer of the group leader too unless it's gonna be
|
|
* a duplicate.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
do_notify_parent_cldstop(current, false, why);
|
|
|
|
if (ptrace_reparented(current->group_leader))
|
|
do_notify_parent_cldstop(current->group_leader,
|
|
true, why);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
goto relock;
|
|
}
|
|
|
|
for (;;) {
|
|
struct k_sigaction *ka;
|
|
|
|
if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
|
|
do_signal_stop(0))
|
|
goto relock;
|
|
|
|
if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
|
|
do_jobctl_trap();
|
|
spin_unlock_irq(&sighand->siglock);
|
|
goto relock;
|
|
}
|
|
|
|
signr = dequeue_signal(current, ¤t->blocked, info);
|
|
|
|
if (!signr)
|
|
break; /* will return 0 */
|
|
|
|
if (unlikely(current->ptrace) && signr != SIGKILL) {
|
|
signr = ptrace_signal(signr, info,
|
|
regs, cookie);
|
|
if (!signr)
|
|
continue;
|
|
}
|
|
|
|
ka = &sighand->action[signr-1];
|
|
|
|
/* Trace actually delivered signals. */
|
|
trace_signal_deliver(signr, info, ka);
|
|
|
|
if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
|
|
continue;
|
|
if (ka->sa.sa_handler != SIG_DFL) {
|
|
/* Run the handler. */
|
|
*return_ka = *ka;
|
|
|
|
if (ka->sa.sa_flags & SA_ONESHOT)
|
|
ka->sa.sa_handler = SIG_DFL;
|
|
|
|
break; /* will return non-zero "signr" value */
|
|
}
|
|
|
|
/*
|
|
* Now we are doing the default action for this signal.
|
|
*/
|
|
if (sig_kernel_ignore(signr)) /* Default is nothing. */
|
|
continue;
|
|
|
|
/*
|
|
* Global init gets no signals it doesn't want.
|
|
* Container-init gets no signals it doesn't want from same
|
|
* container.
|
|
*
|
|
* Note that if global/container-init sees a sig_kernel_only()
|
|
* signal here, the signal must have been generated internally
|
|
* or must have come from an ancestor namespace. In either
|
|
* case, the signal cannot be dropped.
|
|
*/
|
|
if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
|
|
!sig_kernel_only(signr))
|
|
continue;
|
|
|
|
if (sig_kernel_stop(signr)) {
|
|
/*
|
|
* The default action is to stop all threads in
|
|
* the thread group. The job control signals
|
|
* do nothing in an orphaned pgrp, but SIGSTOP
|
|
* always works. Note that siglock needs to be
|
|
* dropped during the call to is_orphaned_pgrp()
|
|
* because of lock ordering with tasklist_lock.
|
|
* This allows an intervening SIGCONT to be posted.
|
|
* We need to check for that and bail out if necessary.
|
|
*/
|
|
if (signr != SIGSTOP) {
|
|
spin_unlock_irq(&sighand->siglock);
|
|
|
|
/* signals can be posted during this window */
|
|
|
|
if (is_current_pgrp_orphaned())
|
|
goto relock;
|
|
|
|
spin_lock_irq(&sighand->siglock);
|
|
}
|
|
|
|
if (likely(do_signal_stop(info->si_signo))) {
|
|
/* It released the siglock. */
|
|
goto relock;
|
|
}
|
|
|
|
/*
|
|
* We didn't actually stop, due to a race
|
|
* with SIGCONT or something like that.
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
spin_unlock_irq(&sighand->siglock);
|
|
|
|
/*
|
|
* Anything else is fatal, maybe with a core dump.
|
|
*/
|
|
current->flags |= PF_SIGNALED;
|
|
|
|
if (sig_kernel_coredump(signr)) {
|
|
if (print_fatal_signals)
|
|
print_fatal_signal(regs, info->si_signo);
|
|
/*
|
|
* If it was able to dump core, this kills all
|
|
* other threads in the group and synchronizes with
|
|
* their demise. If we lost the race with another
|
|
* thread getting here, it set group_exit_code
|
|
* first and our do_group_exit call below will use
|
|
* that value and ignore the one we pass it.
|
|
*/
|
|
do_coredump(info->si_signo, info->si_signo, regs);
|
|
}
|
|
|
|
/*
|
|
* Death signals, no core dump.
|
|
*/
|
|
do_group_exit(info->si_signo);
|
|
/* NOTREACHED */
|
|
}
|
|
spin_unlock_irq(&sighand->siglock);
|
|
return signr;
|
|
}
|
|
|
|
/**
|
|
* block_sigmask - add @ka's signal mask to current->blocked
|
|
* @ka: action for @signr
|
|
* @signr: signal that has been successfully delivered
|
|
*
|
|
* This function should be called when a signal has succesfully been
|
|
* delivered. It adds the mask of signals for @ka to current->blocked
|
|
* so that they are blocked during the execution of the signal
|
|
* handler. In addition, @signr will be blocked unless %SA_NODEFER is
|
|
* set in @ka->sa.sa_flags.
|
|
*/
|
|
void block_sigmask(struct k_sigaction *ka, int signr)
|
|
{
|
|
sigset_t blocked;
|
|
|
|
sigorsets(&blocked, ¤t->blocked, &ka->sa.sa_mask);
|
|
if (!(ka->sa.sa_flags & SA_NODEFER))
|
|
sigaddset(&blocked, signr);
|
|
set_current_blocked(&blocked);
|
|
}
|
|
|
|
/*
|
|
* It could be that complete_signal() picked us to notify about the
|
|
* group-wide signal. Other threads should be notified now to take
|
|
* the shared signals in @which since we will not.
|
|
*/
|
|
static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
|
|
{
|
|
sigset_t retarget;
|
|
struct task_struct *t;
|
|
|
|
sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
|
|
if (sigisemptyset(&retarget))
|
|
return;
|
|
|
|
t = tsk;
|
|
while_each_thread(tsk, t) {
|
|
if (t->flags & PF_EXITING)
|
|
continue;
|
|
|
|
if (!has_pending_signals(&retarget, &t->blocked))
|
|
continue;
|
|
/* Remove the signals this thread can handle. */
|
|
sigandsets(&retarget, &retarget, &t->blocked);
|
|
|
|
if (!signal_pending(t))
|
|
signal_wake_up(t, 0);
|
|
|
|
if (sigisemptyset(&retarget))
|
|
break;
|
|
}
|
|
}
|
|
|
|
void exit_signals(struct task_struct *tsk)
|
|
{
|
|
int group_stop = 0;
|
|
sigset_t unblocked;
|
|
|
|
/*
|
|
* @tsk is about to have PF_EXITING set - lock out users which
|
|
* expect stable threadgroup.
|
|
*/
|
|
threadgroup_change_begin(tsk);
|
|
|
|
if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
|
|
tsk->flags |= PF_EXITING;
|
|
threadgroup_change_end(tsk);
|
|
return;
|
|
}
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
/*
|
|
* From now this task is not visible for group-wide signals,
|
|
* see wants_signal(), do_signal_stop().
|
|
*/
|
|
tsk->flags |= PF_EXITING;
|
|
|
|
threadgroup_change_end(tsk);
|
|
|
|
if (!signal_pending(tsk))
|
|
goto out;
|
|
|
|
unblocked = tsk->blocked;
|
|
signotset(&unblocked);
|
|
retarget_shared_pending(tsk, &unblocked);
|
|
|
|
if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
|
|
task_participate_group_stop(tsk))
|
|
group_stop = CLD_STOPPED;
|
|
out:
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
/*
|
|
* If group stop has completed, deliver the notification. This
|
|
* should always go to the real parent of the group leader.
|
|
*/
|
|
if (unlikely(group_stop)) {
|
|
read_lock(&tasklist_lock);
|
|
do_notify_parent_cldstop(tsk, false, group_stop);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(recalc_sigpending);
|
|
EXPORT_SYMBOL_GPL(dequeue_signal);
|
|
EXPORT_SYMBOL(flush_signals);
|
|
EXPORT_SYMBOL(force_sig);
|
|
EXPORT_SYMBOL(send_sig);
|
|
EXPORT_SYMBOL(send_sig_info);
|
|
EXPORT_SYMBOL(sigprocmask);
|
|
EXPORT_SYMBOL(block_all_signals);
|
|
EXPORT_SYMBOL(unblock_all_signals);
|
|
|
|
|
|
/*
|
|
* System call entry points.
|
|
*/
|
|
|
|
/**
|
|
* sys_restart_syscall - restart a system call
|
|
*/
|
|
SYSCALL_DEFINE0(restart_syscall)
|
|
{
|
|
struct restart_block *restart = ¤t_thread_info()->restart_block;
|
|
return restart->fn(restart);
|
|
}
|
|
|
|
long do_no_restart_syscall(struct restart_block *param)
|
|
{
|
|
return -EINTR;
|
|
}
|
|
|
|
static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
|
|
{
|
|
if (signal_pending(tsk) && !thread_group_empty(tsk)) {
|
|
sigset_t newblocked;
|
|
/* A set of now blocked but previously unblocked signals. */
|
|
sigandnsets(&newblocked, newset, ¤t->blocked);
|
|
retarget_shared_pending(tsk, &newblocked);
|
|
}
|
|
tsk->blocked = *newset;
|
|
recalc_sigpending();
|
|
}
|
|
|
|
/**
|
|
* set_current_blocked - change current->blocked mask
|
|
* @newset: new mask
|
|
*
|
|
* It is wrong to change ->blocked directly, this helper should be used
|
|
* to ensure the process can't miss a shared signal we are going to block.
|
|
*/
|
|
void set_current_blocked(const sigset_t *newset)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
__set_task_blocked(tsk, newset);
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
}
|
|
|
|
/*
|
|
* This is also useful for kernel threads that want to temporarily
|
|
* (or permanently) block certain signals.
|
|
*
|
|
* NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
|
|
* interface happily blocks "unblockable" signals like SIGKILL
|
|
* and friends.
|
|
*/
|
|
int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
sigset_t newset;
|
|
|
|
/* Lockless, only current can change ->blocked, never from irq */
|
|
if (oldset)
|
|
*oldset = tsk->blocked;
|
|
|
|
switch (how) {
|
|
case SIG_BLOCK:
|
|
sigorsets(&newset, &tsk->blocked, set);
|
|
break;
|
|
case SIG_UNBLOCK:
|
|
sigandnsets(&newset, &tsk->blocked, set);
|
|
break;
|
|
case SIG_SETMASK:
|
|
newset = *set;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
set_current_blocked(&newset);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sys_rt_sigprocmask - change the list of currently blocked signals
|
|
* @how: whether to add, remove, or set signals
|
|
* @nset: stores pending signals
|
|
* @oset: previous value of signal mask if non-null
|
|
* @sigsetsize: size of sigset_t type
|
|
*/
|
|
SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
|
|
sigset_t __user *, oset, size_t, sigsetsize)
|
|
{
|
|
sigset_t old_set, new_set;
|
|
int error;
|
|
|
|
/* XXX: Don't preclude handling different sized sigset_t's. */
|
|
if (sigsetsize != sizeof(sigset_t))
|
|
return -EINVAL;
|
|
|
|
old_set = current->blocked;
|
|
|
|
if (nset) {
|
|
if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
|
|
return -EFAULT;
|
|
sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
|
|
|
|
error = sigprocmask(how, &new_set, NULL);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
if (oset) {
|
|
if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
long do_sigpending(void __user *set, unsigned long sigsetsize)
|
|
{
|
|
long error = -EINVAL;
|
|
sigset_t pending;
|
|
|
|
if (sigsetsize > sizeof(sigset_t))
|
|
goto out;
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
sigorsets(&pending, ¤t->pending.signal,
|
|
¤t->signal->shared_pending.signal);
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
/* Outside the lock because only this thread touches it. */
|
|
sigandsets(&pending, ¤t->blocked, &pending);
|
|
|
|
error = -EFAULT;
|
|
if (!copy_to_user(set, &pending, sigsetsize))
|
|
error = 0;
|
|
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* sys_rt_sigpending - examine a pending signal that has been raised
|
|
* while blocked
|
|
* @set: stores pending signals
|
|
* @sigsetsize: size of sigset_t type or larger
|
|
*/
|
|
SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
|
|
{
|
|
return do_sigpending(set, sigsetsize);
|
|
}
|
|
|
|
#ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
|
|
|
|
int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
|
|
{
|
|
int err;
|
|
|
|
if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
|
|
return -EFAULT;
|
|
if (from->si_code < 0)
|
|
return __copy_to_user(to, from, sizeof(siginfo_t))
|
|
? -EFAULT : 0;
|
|
/*
|
|
* If you change siginfo_t structure, please be sure
|
|
* this code is fixed accordingly.
|
|
* Please remember to update the signalfd_copyinfo() function
|
|
* inside fs/signalfd.c too, in case siginfo_t changes.
|
|
* It should never copy any pad contained in the structure
|
|
* to avoid security leaks, but must copy the generic
|
|
* 3 ints plus the relevant union member.
|
|
*/
|
|
err = __put_user(from->si_signo, &to->si_signo);
|
|
err |= __put_user(from->si_errno, &to->si_errno);
|
|
err |= __put_user((short)from->si_code, &to->si_code);
|
|
switch (from->si_code & __SI_MASK) {
|
|
case __SI_KILL:
|
|
err |= __put_user(from->si_pid, &to->si_pid);
|
|
err |= __put_user(from->si_uid, &to->si_uid);
|
|
break;
|
|
case __SI_TIMER:
|
|
err |= __put_user(from->si_tid, &to->si_tid);
|
|
err |= __put_user(from->si_overrun, &to->si_overrun);
|
|
err |= __put_user(from->si_ptr, &to->si_ptr);
|
|
break;
|
|
case __SI_POLL:
|
|
err |= __put_user(from->si_band, &to->si_band);
|
|
err |= __put_user(from->si_fd, &to->si_fd);
|
|
break;
|
|
case __SI_FAULT:
|
|
err |= __put_user(from->si_addr, &to->si_addr);
|
|
#ifdef __ARCH_SI_TRAPNO
|
|
err |= __put_user(from->si_trapno, &to->si_trapno);
|
|
#endif
|
|
#ifdef BUS_MCEERR_AO
|
|
/*
|
|
* Other callers might not initialize the si_lsb field,
|
|
* so check explicitly for the right codes here.
|
|
*/
|
|
if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
|
|
err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
|
|
#endif
|
|
break;
|
|
case __SI_CHLD:
|
|
err |= __put_user(from->si_pid, &to->si_pid);
|
|
err |= __put_user(from->si_uid, &to->si_uid);
|
|
err |= __put_user(from->si_status, &to->si_status);
|
|
err |= __put_user(from->si_utime, &to->si_utime);
|
|
err |= __put_user(from->si_stime, &to->si_stime);
|
|
break;
|
|
case __SI_RT: /* This is not generated by the kernel as of now. */
|
|
case __SI_MESGQ: /* But this is */
|
|
err |= __put_user(from->si_pid, &to->si_pid);
|
|
err |= __put_user(from->si_uid, &to->si_uid);
|
|
err |= __put_user(from->si_ptr, &to->si_ptr);
|
|
break;
|
|
#ifdef __ARCH_SIGSYS
|
|
case __SI_SYS:
|
|
err |= __put_user(from->si_call_addr, &to->si_call_addr);
|
|
err |= __put_user(from->si_syscall, &to->si_syscall);
|
|
err |= __put_user(from->si_arch, &to->si_arch);
|
|
break;
|
|
#endif
|
|
default: /* this is just in case for now ... */
|
|
err |= __put_user(from->si_pid, &to->si_pid);
|
|
err |= __put_user(from->si_uid, &to->si_uid);
|
|
break;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
#endif
|
|
|
|
/**
|
|
* do_sigtimedwait - wait for queued signals specified in @which
|
|
* @which: queued signals to wait for
|
|
* @info: if non-null, the signal's siginfo is returned here
|
|
* @ts: upper bound on process time suspension
|
|
*/
|
|
int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
|
|
const struct timespec *ts)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
long timeout = MAX_SCHEDULE_TIMEOUT;
|
|
sigset_t mask = *which;
|
|
int sig;
|
|
|
|
if (ts) {
|
|
if (!timespec_valid(ts))
|
|
return -EINVAL;
|
|
timeout = timespec_to_jiffies(ts);
|
|
/*
|
|
* We can be close to the next tick, add another one
|
|
* to ensure we will wait at least the time asked for.
|
|
*/
|
|
if (ts->tv_sec || ts->tv_nsec)
|
|
timeout++;
|
|
}
|
|
|
|
/*
|
|
* Invert the set of allowed signals to get those we want to block.
|
|
*/
|
|
sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
|
|
signotset(&mask);
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
sig = dequeue_signal(tsk, &mask, info);
|
|
if (!sig && timeout) {
|
|
/*
|
|
* None ready, temporarily unblock those we're interested
|
|
* while we are sleeping in so that we'll be awakened when
|
|
* they arrive. Unblocking is always fine, we can avoid
|
|
* set_current_blocked().
|
|
*/
|
|
tsk->real_blocked = tsk->blocked;
|
|
sigandsets(&tsk->blocked, &tsk->blocked, &mask);
|
|
recalc_sigpending();
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
timeout = schedule_timeout_interruptible(timeout);
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
__set_task_blocked(tsk, &tsk->real_blocked);
|
|
siginitset(&tsk->real_blocked, 0);
|
|
sig = dequeue_signal(tsk, &mask, info);
|
|
}
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
if (sig)
|
|
return sig;
|
|
return timeout ? -EINTR : -EAGAIN;
|
|
}
|
|
|
|
/**
|
|
* sys_rt_sigtimedwait - synchronously wait for queued signals specified
|
|
* in @uthese
|
|
* @uthese: queued signals to wait for
|
|
* @uinfo: if non-null, the signal's siginfo is returned here
|
|
* @uts: upper bound on process time suspension
|
|
* @sigsetsize: size of sigset_t type
|
|
*/
|
|
SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
|
|
siginfo_t __user *, uinfo, const struct timespec __user *, uts,
|
|
size_t, sigsetsize)
|
|
{
|
|
sigset_t these;
|
|
struct timespec ts;
|
|
siginfo_t info;
|
|
int ret;
|
|
|
|
/* XXX: Don't preclude handling different sized sigset_t's. */
|
|
if (sigsetsize != sizeof(sigset_t))
|
|
return -EINVAL;
|
|
|
|
if (copy_from_user(&these, uthese, sizeof(these)))
|
|
return -EFAULT;
|
|
|
|
if (uts) {
|
|
if (copy_from_user(&ts, uts, sizeof(ts)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
|
|
|
|
if (ret > 0 && uinfo) {
|
|
if (copy_siginfo_to_user(uinfo, &info))
|
|
ret = -EFAULT;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_kill - send a signal to a process
|
|
* @pid: the PID of the process
|
|
* @sig: signal to be sent
|
|
*/
|
|
SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
|
|
{
|
|
struct siginfo info;
|
|
|
|
info.si_signo = sig;
|
|
info.si_errno = 0;
|
|
info.si_code = SI_USER;
|
|
info.si_pid = task_tgid_vnr(current);
|
|
info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
|
|
|
|
return kill_something_info(sig, &info, pid);
|
|
}
|
|
|
|
static int
|
|
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
|
|
{
|
|
struct task_struct *p;
|
|
int error = -ESRCH;
|
|
|
|
rcu_read_lock();
|
|
p = find_task_by_vpid(pid);
|
|
if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
|
|
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) {
|
|
error = do_send_sig_info(sig, info, p, false);
|
|
/*
|
|
* If lock_task_sighand() failed we pretend the task
|
|
* dies after receiving the signal. The window is tiny,
|
|
* and the signal is private anyway.
|
|
*/
|
|
if (unlikely(error == -ESRCH))
|
|
error = 0;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return error;
|
|
}
|
|
|
|
static int do_tkill(pid_t tgid, pid_t pid, int sig)
|
|
{
|
|
struct siginfo info;
|
|
|
|
info.si_signo = sig;
|
|
info.si_errno = 0;
|
|
info.si_code = SI_TKILL;
|
|
info.si_pid = task_tgid_vnr(current);
|
|
info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
|
|
|
|
return do_send_specific(tgid, pid, sig, &info);
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
|
|
{
|
|
/* This is only valid for single tasks */
|
|
if (pid <= 0 || tgid <= 0)
|
|
return -EINVAL;
|
|
|
|
return do_tkill(tgid, pid, sig);
|
|
}
|
|
|
|
/**
|
|
* sys_tkill - send signal to one specific task
|
|
* @pid: the PID of the task
|
|
* @sig: signal to be sent
|
|
*
|
|
* Send a signal to only one task, even if it's a CLONE_THREAD task.
|
|
*/
|
|
SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
|
|
{
|
|
/* This is only valid for single tasks */
|
|
if (pid <= 0)
|
|
return -EINVAL;
|
|
|
|
return do_tkill(0, pid, sig);
|
|
}
|
|
|
|
/**
|
|
* sys_rt_sigqueueinfo - send signal information to a signal
|
|
* @pid: the PID of the thread
|
|
* @sig: signal to be sent
|
|
* @uinfo: signal info to be sent
|
|
*/
|
|
SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
|
|
siginfo_t __user *, uinfo)
|
|
{
|
|
siginfo_t info;
|
|
|
|
if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
|
|
return -EFAULT;
|
|
|
|
/* Not even root can pretend to send signals from the kernel.
|
|
* Nor can they impersonate a kill()/tgkill(), which adds source info.
|
|
*/
|
|
if (info.si_code >= 0 || info.si_code == SI_TKILL) {
|
|
/* We used to allow any < 0 si_code */
|
|
WARN_ON_ONCE(info.si_code < 0);
|
|
return -EPERM;
|
|
}
|
|
info.si_signo = sig;
|
|
|
|
/* POSIX.1b doesn't mention process groups. */
|
|
return kill_proc_info(sig, &info, pid);
|
|
}
|
|
|
|
long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
|
|
{
|
|
/* This is only valid for single tasks */
|
|
if (pid <= 0 || tgid <= 0)
|
|
return -EINVAL;
|
|
|
|
/* Not even root can pretend to send signals from the kernel.
|
|
* Nor can they impersonate a kill()/tgkill(), which adds source info.
|
|
*/
|
|
if (info->si_code >= 0 || info->si_code == SI_TKILL) {
|
|
/* We used to allow any < 0 si_code */
|
|
WARN_ON_ONCE(info->si_code < 0);
|
|
return -EPERM;
|
|
}
|
|
info->si_signo = sig;
|
|
|
|
return do_send_specific(tgid, pid, sig, info);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
|
|
siginfo_t __user *, uinfo)
|
|
{
|
|
siginfo_t info;
|
|
|
|
if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
|
|
return -EFAULT;
|
|
|
|
return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
|
|
}
|
|
|
|
int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
|
|
{
|
|
struct task_struct *t = current;
|
|
struct k_sigaction *k;
|
|
sigset_t mask;
|
|
|
|
if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
|
|
return -EINVAL;
|
|
|
|
k = &t->sighand->action[sig-1];
|
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
if (oact)
|
|
*oact = *k;
|
|
|
|
if (act) {
|
|
sigdelsetmask(&act->sa.sa_mask,
|
|
sigmask(SIGKILL) | sigmask(SIGSTOP));
|
|
*k = *act;
|
|
/*
|
|
* POSIX 3.3.1.3:
|
|
* "Setting a signal action to SIG_IGN for a signal that is
|
|
* pending shall cause the pending signal to be discarded,
|
|
* whether or not it is blocked."
|
|
*
|
|
* "Setting a signal action to SIG_DFL for a signal that is
|
|
* pending and whose default action is to ignore the signal
|
|
* (for example, SIGCHLD), shall cause the pending signal to
|
|
* be discarded, whether or not it is blocked"
|
|
*/
|
|
if (sig_handler_ignored(sig_handler(t, sig), sig)) {
|
|
sigemptyset(&mask);
|
|
sigaddset(&mask, sig);
|
|
rm_from_queue_full(&mask, &t->signal->shared_pending);
|
|
do {
|
|
rm_from_queue_full(&mask, &t->pending);
|
|
t = next_thread(t);
|
|
} while (t != current);
|
|
}
|
|
}
|
|
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
return 0;
|
|
}
|
|
|
|
int
|
|
do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
|
|
{
|
|
stack_t oss;
|
|
int error;
|
|
|
|
oss.ss_sp = (void __user *) current->sas_ss_sp;
|
|
oss.ss_size = current->sas_ss_size;
|
|
oss.ss_flags = sas_ss_flags(sp);
|
|
|
|
if (uss) {
|
|
void __user *ss_sp;
|
|
size_t ss_size;
|
|
int ss_flags;
|
|
|
|
error = -EFAULT;
|
|
if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
|
|
goto out;
|
|
error = __get_user(ss_sp, &uss->ss_sp) |
|
|
__get_user(ss_flags, &uss->ss_flags) |
|
|
__get_user(ss_size, &uss->ss_size);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = -EPERM;
|
|
if (on_sig_stack(sp))
|
|
goto out;
|
|
|
|
error = -EINVAL;
|
|
/*
|
|
* Note - this code used to test ss_flags incorrectly:
|
|
* old code may have been written using ss_flags==0
|
|
* to mean ss_flags==SS_ONSTACK (as this was the only
|
|
* way that worked) - this fix preserves that older
|
|
* mechanism.
|
|
*/
|
|
if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
|
|
goto out;
|
|
|
|
if (ss_flags == SS_DISABLE) {
|
|
ss_size = 0;
|
|
ss_sp = NULL;
|
|
} else {
|
|
error = -ENOMEM;
|
|
if (ss_size < MINSIGSTKSZ)
|
|
goto out;
|
|
}
|
|
|
|
current->sas_ss_sp = (unsigned long) ss_sp;
|
|
current->sas_ss_size = ss_size;
|
|
}
|
|
|
|
error = 0;
|
|
if (uoss) {
|
|
error = -EFAULT;
|
|
if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
|
|
goto out;
|
|
error = __put_user(oss.ss_sp, &uoss->ss_sp) |
|
|
__put_user(oss.ss_size, &uoss->ss_size) |
|
|
__put_user(oss.ss_flags, &uoss->ss_flags);
|
|
}
|
|
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_SIGPENDING
|
|
|
|
/**
|
|
* sys_sigpending - examine pending signals
|
|
* @set: where mask of pending signal is returned
|
|
*/
|
|
SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
|
|
{
|
|
return do_sigpending(set, sizeof(*set));
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef __ARCH_WANT_SYS_SIGPROCMASK
|
|
/**
|
|
* sys_sigprocmask - examine and change blocked signals
|
|
* @how: whether to add, remove, or set signals
|
|
* @nset: signals to add or remove (if non-null)
|
|
* @oset: previous value of signal mask if non-null
|
|
*
|
|
* Some platforms have their own version with special arguments;
|
|
* others support only sys_rt_sigprocmask.
|
|
*/
|
|
|
|
SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
|
|
old_sigset_t __user *, oset)
|
|
{
|
|
old_sigset_t old_set, new_set;
|
|
sigset_t new_blocked;
|
|
|
|
old_set = current->blocked.sig[0];
|
|
|
|
if (nset) {
|
|
if (copy_from_user(&new_set, nset, sizeof(*nset)))
|
|
return -EFAULT;
|
|
new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
|
|
|
|
new_blocked = current->blocked;
|
|
|
|
switch (how) {
|
|
case SIG_BLOCK:
|
|
sigaddsetmask(&new_blocked, new_set);
|
|
break;
|
|
case SIG_UNBLOCK:
|
|
sigdelsetmask(&new_blocked, new_set);
|
|
break;
|
|
case SIG_SETMASK:
|
|
new_blocked.sig[0] = new_set;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
set_current_blocked(&new_blocked);
|
|
}
|
|
|
|
if (oset) {
|
|
if (copy_to_user(oset, &old_set, sizeof(*oset)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_SIGPROCMASK */
|
|
|
|
#ifdef __ARCH_WANT_SYS_RT_SIGACTION
|
|
/**
|
|
* sys_rt_sigaction - alter an action taken by a process
|
|
* @sig: signal to be sent
|
|
* @act: new sigaction
|
|
* @oact: used to save the previous sigaction
|
|
* @sigsetsize: size of sigset_t type
|
|
*/
|
|
SYSCALL_DEFINE4(rt_sigaction, int, sig,
|
|
const struct sigaction __user *, act,
|
|
struct sigaction __user *, oact,
|
|
size_t, sigsetsize)
|
|
{
|
|
struct k_sigaction new_sa, old_sa;
|
|
int ret = -EINVAL;
|
|
|
|
/* XXX: Don't preclude handling different sized sigset_t's. */
|
|
if (sigsetsize != sizeof(sigset_t))
|
|
goto out;
|
|
|
|
if (act) {
|
|
if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
|
|
|
|
if (!ret && oact) {
|
|
if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
|
|
return -EFAULT;
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_RT_SIGACTION */
|
|
|
|
#ifdef __ARCH_WANT_SYS_SGETMASK
|
|
|
|
/*
|
|
* For backwards compatibility. Functionality superseded by sigprocmask.
|
|
*/
|
|
SYSCALL_DEFINE0(sgetmask)
|
|
{
|
|
/* SMP safe */
|
|
return current->blocked.sig[0];
|
|
}
|
|
|
|
SYSCALL_DEFINE1(ssetmask, int, newmask)
|
|
{
|
|
int old = current->blocked.sig[0];
|
|
sigset_t newset;
|
|
|
|
siginitset(&newset, newmask & ~(sigmask(SIGKILL) | sigmask(SIGSTOP)));
|
|
set_current_blocked(&newset);
|
|
|
|
return old;
|
|
}
|
|
#endif /* __ARCH_WANT_SGETMASK */
|
|
|
|
#ifdef __ARCH_WANT_SYS_SIGNAL
|
|
/*
|
|
* For backwards compatibility. Functionality superseded by sigaction.
|
|
*/
|
|
SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
|
|
{
|
|
struct k_sigaction new_sa, old_sa;
|
|
int ret;
|
|
|
|
new_sa.sa.sa_handler = handler;
|
|
new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
|
|
sigemptyset(&new_sa.sa.sa_mask);
|
|
|
|
ret = do_sigaction(sig, &new_sa, &old_sa);
|
|
|
|
return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_SIGNAL */
|
|
|
|
#ifdef __ARCH_WANT_SYS_PAUSE
|
|
|
|
SYSCALL_DEFINE0(pause)
|
|
{
|
|
while (!signal_pending(current)) {
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
schedule();
|
|
}
|
|
return -ERESTARTNOHAND;
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef HAVE_SET_RESTORE_SIGMASK
|
|
int sigsuspend(sigset_t *set)
|
|
{
|
|
sigdelsetmask(set, sigmask(SIGKILL)|sigmask(SIGSTOP));
|
|
|
|
current->saved_sigmask = current->blocked;
|
|
set_current_blocked(set);
|
|
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
schedule();
|
|
set_restore_sigmask();
|
|
return -ERESTARTNOHAND;
|
|
}
|
|
#endif
|
|
|
|
#ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
|
|
/**
|
|
* sys_rt_sigsuspend - replace the signal mask for a value with the
|
|
* @unewset value until a signal is received
|
|
* @unewset: new signal mask value
|
|
* @sigsetsize: size of sigset_t type
|
|
*/
|
|
SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
|
|
{
|
|
sigset_t newset;
|
|
|
|
/* XXX: Don't preclude handling different sized sigset_t's. */
|
|
if (sigsetsize != sizeof(sigset_t))
|
|
return -EINVAL;
|
|
|
|
if (copy_from_user(&newset, unewset, sizeof(newset)))
|
|
return -EFAULT;
|
|
return sigsuspend(&newset);
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
|
|
|
|
__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
void __init signals_init(void)
|
|
{
|
|
sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
|
|
}
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
#include <linux/kdb.h>
|
|
/*
|
|
* kdb_send_sig_info - Allows kdb to send signals without exposing
|
|
* signal internals. This function checks if the required locks are
|
|
* available before calling the main signal code, to avoid kdb
|
|
* deadlocks.
|
|
*/
|
|
void
|
|
kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
|
|
{
|
|
static struct task_struct *kdb_prev_t;
|
|
int sig, new_t;
|
|
if (!spin_trylock(&t->sighand->siglock)) {
|
|
kdb_printf("Can't do kill command now.\n"
|
|
"The sigmask lock is held somewhere else in "
|
|
"kernel, try again later\n");
|
|
return;
|
|
}
|
|
spin_unlock(&t->sighand->siglock);
|
|
new_t = kdb_prev_t != t;
|
|
kdb_prev_t = t;
|
|
if (t->state != TASK_RUNNING && new_t) {
|
|
kdb_printf("Process is not RUNNING, sending a signal from "
|
|
"kdb risks deadlock\n"
|
|
"on the run queue locks. "
|
|
"The signal has _not_ been sent.\n"
|
|
"Reissue the kill command if you want to risk "
|
|
"the deadlock.\n");
|
|
return;
|
|
}
|
|
sig = info->si_signo;
|
|
if (send_sig_info(sig, info, t))
|
|
kdb_printf("Fail to deliver Signal %d to process %d.\n",
|
|
sig, t->pid);
|
|
else
|
|
kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
|
|
}
|
|
#endif /* CONFIG_KGDB_KDB */
|