diff options
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 173 |
1 files changed, 36 insertions, 137 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 2b4087d545a3..364fc95bf97c 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -12,7 +12,6 @@ #include <linux/slab.h> #include <linux/module.h> -#include <linux/smp_lock.h> #include <linux/init.h> #include <linux/sched.h> #include <linux/fs.h> @@ -22,6 +21,7 @@ #include <linux/syscalls.h> #include <linux/ptrace.h> #include <linux/signal.h> +#include <linux/signalfd.h> #include <linux/capability.h> #include <linux/freezer.h> #include <linux/pid_namespace.h> @@ -39,125 +39,6 @@ static struct kmem_cache *sigqueue_cachep; -/* - * In POSIX a signal is sent either to a specific thread (Linux task) - * or to the process as a whole (Linux thread group). How the signal - * is sent determines whether it's to one thread or the whole group, - * which determines which signal mask(s) are involved in blocking it - * from being delivered until later. When the signal is delivered, - * either it's caught or ignored by a user handler or it has a default - * effect that applies to the whole thread group (POSIX process). - * - * The possible effects an unblocked signal set to SIG_DFL can have are: - * ignore - Nothing Happens - * terminate - kill the process, i.e. all threads in the group, - * similar to exit_group. The group leader (only) reports - * WIFSIGNALED status to its parent. - * coredump - write a core dump file describing all threads using - * the same mm and then kill all those threads - * stop - stop all the threads in the group, i.e. TASK_STOPPED state - * - * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored. - * Other signals when not blocked and set to SIG_DFL behaves as follows. - * The job control signals also have other special effects. - * - * +--------------------+------------------+ - * | POSIX signal | default action | - * +--------------------+------------------+ - * | SIGHUP | terminate | - * | SIGINT | terminate | - * | SIGQUIT | coredump | - * | SIGILL | coredump | - * | SIGTRAP | coredump | - * | SIGABRT/SIGIOT | coredump | - * | SIGBUS | coredump | - * | SIGFPE | coredump | - * | SIGKILL | terminate(+) | - * | SIGUSR1 | terminate | - * | SIGSEGV | coredump | - * | SIGUSR2 | terminate | - * | SIGPIPE | terminate | - * | SIGALRM | terminate | - * | SIGTERM | terminate | - * | SIGCHLD | ignore | - * | SIGCONT | ignore(*) | - * | SIGSTOP | stop(*)(+) | - * | SIGTSTP | stop(*) | - * | SIGTTIN | stop(*) | - * | SIGTTOU | stop(*) | - * | SIGURG | ignore | - * | SIGXCPU | coredump | - * | SIGXFSZ | coredump | - * | SIGVTALRM | terminate | - * | SIGPROF | terminate | - * | SIGPOLL/SIGIO | terminate | - * | SIGSYS/SIGUNUSED | coredump | - * | SIGSTKFLT | terminate | - * | SIGWINCH | ignore | - * | SIGPWR | terminate | - * | SIGRTMIN-SIGRTMAX | terminate | - * +--------------------+------------------+ - * | non-POSIX signal | default action | - * +--------------------+------------------+ - * | SIGEMT | coredump | - * +--------------------+------------------+ - * - * (+) For SIGKILL and SIGSTOP the action is "always", not just "default". - * (*) Special job control effects: - * When SIGCONT is sent, it resumes the process (all threads in the group) - * from TASK_STOPPED state and also clears any pending/queued stop signals - * (any of those marked with "stop(*)"). This happens regardless of blocking, - * catching, or ignoring SIGCONT. When any stop signal is sent, it clears - * any pending/queued SIGCONT signals; this happens regardless of blocking, - * catching, or ignored the stop signal, though (except for SIGSTOP) the - * default action of stopping the process may happen later or never. - */ - -#ifdef SIGEMT -#define M_SIGEMT M(SIGEMT) -#else -#define M_SIGEMT 0 -#endif - -#if SIGRTMIN > BITS_PER_LONG -#define M(sig) (1ULL << ((sig)-1)) -#else -#define M(sig) (1UL << ((sig)-1)) -#endif -#define T(sig, mask) (M(sig) & (mask)) - -#define SIG_KERNEL_ONLY_MASK (\ - M(SIGKILL) | M(SIGSTOP) ) - -#define SIG_KERNEL_STOP_MASK (\ - M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) ) - -#define SIG_KERNEL_COREDUMP_MASK (\ - M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \ - M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \ - M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT ) - -#define SIG_KERNEL_IGNORE_MASK (\ - M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) ) - -#define sig_kernel_only(sig) \ - (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK)) -#define sig_kernel_coredump(sig) \ - (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK)) -#define sig_kernel_ignore(sig) \ - (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK)) -#define sig_kernel_stop(sig) \ - (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK)) - -#define sig_needs_tasklist(sig) ((sig) == SIGCONT) - -#define sig_user_defined(t, signr) \ - (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \ - ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN)) - -#define sig_fatal(t, signr) \ - (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \ - (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL) static int sig_ignored(struct task_struct *t, int sig) { @@ -233,8 +114,7 @@ void recalc_sigpending(void) /* Given the mask, find the first available signal that should be serviced. */ -static int -next_signal(struct sigpending *pending, sigset_t *mask) +int next_signal(struct sigpending *pending, sigset_t *mask) { unsigned long i, *s, *m, x; int sig = 0; @@ -329,6 +209,16 @@ void flush_signals(struct task_struct *t) spin_unlock_irqrestore(&t->sighand->siglock, flags); } +void ignore_signals(struct task_struct *t) +{ + int i; + + for (i = 0; i < _NSIG; ++i) + t->sighand->action[i].sa.sa_handler = SIG_IGN; + + flush_signals(t); +} + /* * Flush all handlers for a task. */ @@ -607,6 +497,11 @@ static int check_kill_permission(int sig, struct siginfo *info, int error = -EINVAL; if (!valid_signal(sig)) return error; + + error = audit_signal_info(sig, t); /* Let audit system see the signal */ + if (error) + return error; + error = -EPERM; if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) && ((sig != SIGCONT) || @@ -616,10 +511,7 @@ static int check_kill_permission(int sig, struct siginfo *info, && !capable(CAP_KILL)) return error; - error = security_task_kill(t, info, sig, 0); - if (!error) - audit_signal_info(sig, t); /* Let audit system see the signal */ - return error; + return security_task_kill(t, info, sig, 0); } /* forward decl */ @@ -740,6 +632,12 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, int ret = 0; /* + * Deliver the signal to listening signalfds. This must be called + * with the sighand lock held. + */ + signalfd_notify(t, sig); + + /* * fast-pathed signals for kernel-internal things like SIGSTOP * or SIGKILL. */ @@ -1033,17 +931,6 @@ void zap_other_threads(struct task_struct *p) if (t->exit_state) continue; - /* - * We don't want to notify the parent, since we are - * killed as part of a thread group due to another - * thread doing an execve() or similar. So set the - * exit signal to -1 to allow immediate reaping of - * the process. But don't detach the thread group - * leader. - */ - if (t != p->group_leader) - t->exit_signal = -1; - /* SIGKILL will be handled before any pending SIGSTOP */ sigaddset(&t->pending.signal, SIGKILL); signal_wake_up(t, 1); @@ -1401,6 +1288,11 @@ int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) ret = 1; goto out; } + /* + * Deliver the signal to listening signalfds. This must be called + * with the sighand lock held. + */ + signalfd_notify(p, sig); list_add_tail(&q->list, &p->pending.list); sigaddset(&p->pending.signal, sig); @@ -1444,6 +1336,11 @@ send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p) q->info.si_overrun++; goto out; } + /* + * Deliver the signal to listening signalfds. This must be called + * with the sighand lock held. + */ + signalfd_notify(p, sig); /* * Put this signal on the shared-pending queue. @@ -2104,6 +2001,8 @@ int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from) /* * 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. |