/* $NetBSD: sys_sig.c,v 1.47.4.4 2024/08/07 10:11:45 martin Exp $ */ /*- * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Andrew Doran. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_sig.c 8.14 (Berkeley) 5/14/95 */ #include __KERNEL_RCSID(0, "$NetBSD: sys_sig.c,v 1.47.4.4 2024/08/07 10:11:45 martin Exp $"); #include "opt_dtrace.h" #include #include #include #include #include #include #include #include #include #include #include #include SDT_PROVIDER_DECLARE(proc); SDT_PROBE_DEFINE2(proc, kernel, , signal__clear, "int", /* signal */ "ksiginfo_t *"); /* signal-info */ int sys___sigaction_sigtramp(struct lwp *l, const struct sys___sigaction_sigtramp_args *uap, register_t *retval) { /* { syscallarg(int) signum; syscallarg(const struct sigaction *) nsa; syscallarg(struct sigaction *) osa; syscallarg(void *) tramp; syscallarg(int) vers; } */ struct sigaction nsa, osa; int error; if (SCARG(uap, nsa)) { error = copyin(SCARG(uap, nsa), &nsa, sizeof(nsa)); if (error) return (error); } error = sigaction1(l, SCARG(uap, signum), SCARG(uap, nsa) ? &nsa : 0, SCARG(uap, osa) ? &osa : 0, SCARG(uap, tramp), SCARG(uap, vers)); if (error) return (error); if (SCARG(uap, osa)) { error = copyout(&osa, SCARG(uap, osa), sizeof(osa)); if (error) return (error); } return 0; } /* * Manipulate signal mask. Note that we receive new mask, not pointer, and * return old mask as return value; the library stub does the rest. */ int sys___sigprocmask14(struct lwp *l, const struct sys___sigprocmask14_args *uap, register_t *retval) { /* { syscallarg(int) how; syscallarg(const sigset_t *) set; syscallarg(sigset_t *) oset; } */ struct proc *p = l->l_proc; sigset_t nss, oss; int error; if (SCARG(uap, set)) { error = copyin(SCARG(uap, set), &nss, sizeof(nss)); if (error) return error; } mutex_enter(p->p_lock); error = sigprocmask1(l, SCARG(uap, how), SCARG(uap, set) ? &nss : 0, SCARG(uap, oset) ? &oss : 0); mutex_exit(p->p_lock); if (error) return error; if (SCARG(uap, oset)) { error = copyout(&oss, SCARG(uap, oset), sizeof(oss)); if (error) return error; } return 0; } int sys___sigpending14(struct lwp *l, const struct sys___sigpending14_args *uap, register_t *retval) { /* { syscallarg(sigset_t *) set; } */ sigset_t ss; sigpending1(l, &ss); return copyout(&ss, SCARG(uap, set), sizeof(ss)); } /* * Suspend process until signal, providing mask to be set in the meantime. * Note nonstandard calling convention: libc stub passes mask, not pointer, * to save a copyin. */ int sys___sigsuspend14(struct lwp *l, const struct sys___sigsuspend14_args *uap, register_t *retval) { /* { syscallarg(const sigset_t *) set; } */ sigset_t ss; int error; if (SCARG(uap, set)) { error = copyin(SCARG(uap, set), &ss, sizeof(ss)); if (error) return error; } return sigsuspend1(l, SCARG(uap, set) ? &ss : 0); } int sys___sigaltstack14(struct lwp *l, const struct sys___sigaltstack14_args *uap, register_t *retval) { /* { syscallarg(const struct sigaltstack *) nss; syscallarg(struct sigaltstack *) oss; } */ struct sigaltstack nss, oss; int error; if (SCARG(uap, nss)) { error = copyin(SCARG(uap, nss), &nss, sizeof(nss)); if (error) return error; } error = sigaltstack1(l, SCARG(uap, nss) ? &nss : 0, SCARG(uap, oss) ? &oss : 0); if (error) return error; if (SCARG(uap, oss)) { error = copyout(&oss, SCARG(uap, oss), sizeof(oss)); if (error) return error; } return 0; } int kill1(struct lwp *l, pid_t pid, ksiginfo_t *ksi, register_t *retval) { int error; struct proc *p; if ((u_int)ksi->ksi_signo >= NSIG) return EINVAL; if (pid != l->l_proc->p_pid) { if (ksi->ksi_pid != l->l_proc->p_pid) return EPERM; if (ksi->ksi_uid != kauth_cred_geteuid(l->l_cred)) return EPERM; switch (ksi->ksi_code) { case SI_USER: case SI_QUEUE: break; default: return EPERM; } } if (pid > 0) { /* kill single process */ mutex_enter(proc_lock); p = proc_find_raw(pid); if (p == NULL || (p->p_stat != SACTIVE && p->p_stat != SSTOP)) { mutex_exit(proc_lock); /* IEEE Std 1003.1-2001: return success for zombies */ return p ? 0 : ESRCH; } mutex_enter(p->p_lock); error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_SIGNAL, p, KAUTH_ARG(ksi->ksi_signo), NULL, NULL); if (!error && ksi->ksi_signo) { error = kpsignal2(p, ksi); } mutex_exit(p->p_lock); mutex_exit(proc_lock); return error; } switch (pid) { case -1: /* broadcast signal */ return killpg1(l, ksi, 0, 1); case 0: /* signal own process group */ return killpg1(l, ksi, 0, 0); default: /* negative explicit process group */ if (pid <= INT_MIN) return ESRCH; return killpg1(l, ksi, -pid, 0); } /* NOTREACHED */ } int sys_sigqueueinfo(struct lwp *l, const struct sys_sigqueueinfo_args *uap, register_t *retval) { /* { syscallarg(pid_t int) pid; syscallarg(const siginfo_t *) info; } */ ksiginfo_t ksi; int error; KSI_INIT(&ksi); if ((error = copyin(&SCARG(uap, info)->_info, &ksi.ksi_info, sizeof(ksi.ksi_info))) != 0) return error; return kill1(l, SCARG(uap, pid), &ksi, retval); } int sys_kill(struct lwp *l, const struct sys_kill_args *uap, register_t *retval) { /* { syscallarg(pid_t) pid; syscallarg(int) signum; } */ ksiginfo_t ksi; KSI_INIT(&ksi); ksi.ksi_signo = SCARG(uap, signum); ksi.ksi_code = SI_USER; ksi.ksi_pid = l->l_proc->p_pid; ksi.ksi_uid = kauth_cred_geteuid(l->l_cred); return kill1(l, SCARG(uap, pid), &ksi, retval); } int sys_getcontext(struct lwp *l, const struct sys_getcontext_args *uap, register_t *retval) { /* { syscallarg(struct __ucontext *) ucp; } */ struct proc *p = l->l_proc; ucontext_t uc; memset(&uc, 0, sizeof(uc)); mutex_enter(p->p_lock); getucontext(l, &uc); mutex_exit(p->p_lock); return copyout(&uc, SCARG(uap, ucp), sizeof (*SCARG(uap, ucp))); } int sys_setcontext(struct lwp *l, const struct sys_setcontext_args *uap, register_t *retval) { /* { syscallarg(const ucontext_t *) ucp; } */ struct proc *p = l->l_proc; ucontext_t uc; int error; error = copyin(SCARG(uap, ucp), &uc, sizeof (uc)); if (error) return error; if ((uc.uc_flags & _UC_CPU) == 0) return EINVAL; mutex_enter(p->p_lock); error = setucontext(l, &uc); mutex_exit(p->p_lock); if (error) return error; return EJUSTRETURN; } /* * sigtimedwait(2) system call, used also for implementation * of sigwaitinfo() and sigwait(). * * This only handles single LWP in signal wait. libpthread provides * its own sigtimedwait() wrapper to DTRT WRT individual threads. */ int sys_____sigtimedwait50(struct lwp *l, const struct sys_____sigtimedwait50_args *uap, register_t *retval) { return sigtimedwait1(l, uap, retval, copyin, copyout, copyin, copyout); } int sigaction1(struct lwp *l, int signum, const struct sigaction *nsa, struct sigaction *osa, const void *tramp, int vers) { struct proc *p; struct sigacts *ps; sigset_t tset; int prop, error; ksiginfoq_t kq; static bool v0v1valid; if (signum <= 0 || signum >= NSIG) return EINVAL; p = l->l_proc; error = 0; ksiginfo_queue_init(&kq); /* * Trampoline ABI version 0 is reserved for the legacy kernel * provided on-stack trampoline. Conversely, if we are using a * non-0 ABI version, we must have a trampoline. Only validate the * vers if a new sigaction was supplied and there was an actual * handler specified (not SIG_IGN or SIG_DFL), which don't require * a trampoline. Emulations use legacy kernel trampolines with * version 0, alternatively check for that too. * * If version < 2, we try to autoload the compat module. Note * that we interlock with the unload check in compat_modcmd() * using kernconfig_lock. If the autoload fails, we don't try it * again for this process. */ if (nsa != NULL && nsa->sa_handler != SIG_IGN && nsa->sa_handler != SIG_DFL) { if (__predict_false(vers < 2)) { if (p->p_flag & PK_32) v0v1valid = true; else if ((p->p_lflag & PL_SIGCOMPAT) == 0) { kernconfig_lock(); (void)module_autoload("compat_16", MODULE_CLASS_ANY); if (sendsig_sigcontext_16_hook.hooked) { /* * We need to remember if the * sigcontext method may be useable, * because libc may use it even * if siginfo is available. */ v0v1valid = true; } mutex_enter(proc_lock); /* * Prevent unload of compat module while * this process remains. */ p->p_lflag |= PL_SIGCOMPAT; mutex_exit(proc_lock); kernconfig_unlock(); } } switch (vers) { case 0: /* sigcontext, kernel supplied trampoline. */ if (tramp != NULL || !v0v1valid) { return EINVAL; } break; case 1: /* sigcontext, user supplied trampoline. */ if (tramp == NULL || !v0v1valid) { return EINVAL; } break; case 2: case 3: /* siginfo, user supplied trampoline. */ if (tramp == NULL) { return EINVAL; } break; default: return EINVAL; } } mutex_enter(p->p_lock); ps = p->p_sigacts; if (osa) sigaction_copy(osa, &SIGACTION_PS(ps, signum)); if (!nsa) goto out; prop = sigprop[signum]; if ((nsa->sa_flags & ~SA_ALLBITS) || (prop & SA_CANTMASK)) { error = EINVAL; goto out; } sigaction_copy(&SIGACTION_PS(ps, signum), nsa); ps->sa_sigdesc[signum].sd_tramp = tramp; ps->sa_sigdesc[signum].sd_vers = vers; sigminusset(&sigcantmask, &SIGACTION_PS(ps, signum).sa_mask); if ((prop & SA_NORESET) != 0) SIGACTION_PS(ps, signum).sa_flags &= ~SA_RESETHAND; if (signum == SIGCHLD) { if (nsa->sa_flags & SA_NOCLDSTOP) p->p_sflag |= PS_NOCLDSTOP; else p->p_sflag &= ~PS_NOCLDSTOP; if (nsa->sa_flags & SA_NOCLDWAIT) { /* * Paranoia: since SA_NOCLDWAIT is implemented by * reparenting the dying child to PID 1 (and trust * it to reap the zombie), PID 1 itself is forbidden * to set SA_NOCLDWAIT. */ if (p->p_pid == 1) p->p_flag &= ~PK_NOCLDWAIT; else p->p_flag |= PK_NOCLDWAIT; } else p->p_flag &= ~PK_NOCLDWAIT; if (nsa->sa_handler == SIG_IGN) { /* * Paranoia: same as above. */ if (p->p_pid == 1) p->p_flag &= ~PK_CLDSIGIGN; else p->p_flag |= PK_CLDSIGIGN; } else p->p_flag &= ~PK_CLDSIGIGN; } if ((nsa->sa_flags & SA_NODEFER) == 0) sigaddset(&SIGACTION_PS(ps, signum).sa_mask, signum); else sigdelset(&SIGACTION_PS(ps, signum).sa_mask, signum); /* * Set bit in p_sigctx.ps_sigignore for signals that are set to * SIG_IGN, and for signals set to SIG_DFL where the default is to * ignore. However, don't put SIGCONT in p_sigctx.ps_sigignore, as * we have to restart the process. */ if (nsa->sa_handler == SIG_IGN || (nsa->sa_handler == SIG_DFL && (prop & SA_IGNORE) != 0)) { /* Never to be seen again. */ sigemptyset(&tset); sigaddset(&tset, signum); sigclearall(p, &tset, &kq); if (signum != SIGCONT) { /* Easier in psignal */ sigaddset(&p->p_sigctx.ps_sigignore, signum); } sigdelset(&p->p_sigctx.ps_sigcatch, signum); } else { sigdelset(&p->p_sigctx.ps_sigignore, signum); if (nsa->sa_handler == SIG_DFL) sigdelset(&p->p_sigctx.ps_sigcatch, signum); else sigaddset(&p->p_sigctx.ps_sigcatch, signum); } /* * Previously held signals may now have become visible. Ensure that * we check for them before returning to userspace. */ if (sigispending(l, 0)) { lwp_lock(l); l->l_flag |= LW_PENDSIG; lwp_unlock(l); } out: mutex_exit(p->p_lock); ksiginfo_queue_drain(&kq); return error; } int sigprocmask1(struct lwp *l, int how, const sigset_t *nss, sigset_t *oss) { sigset_t *mask = &l->l_sigmask; bool more; KASSERT(mutex_owned(l->l_proc->p_lock)); if (oss) { *oss = *mask; } if (nss == NULL) { return 0; } switch (how) { case SIG_BLOCK: sigplusset(nss, mask); more = false; break; case SIG_UNBLOCK: sigminusset(nss, mask); more = true; break; case SIG_SETMASK: *mask = *nss; more = true; break; default: return EINVAL; } sigminusset(&sigcantmask, mask); if (more && sigispending(l, 0)) { /* * Check for pending signals on return to user. */ lwp_lock(l); l->l_flag |= LW_PENDSIG; lwp_unlock(l); } return 0; } void sigpending1(struct lwp *l, sigset_t *ss) { struct proc *p = l->l_proc; mutex_enter(p->p_lock); *ss = l->l_sigpend.sp_set; sigplusset(&p->p_sigpend.sp_set, ss); mutex_exit(p->p_lock); } void sigsuspendsetup(struct lwp *l, const sigset_t *ss) { struct proc *p = l->l_proc; /* * When returning from sigsuspend/pselect/pollts, we want * the old mask to be restored after the * signal handler has finished. Thus, we * save it here and mark the sigctx structure * to indicate this. */ mutex_enter(p->p_lock); l->l_sigrestore = 1; l->l_sigoldmask = l->l_sigmask; l->l_sigmask = *ss; sigminusset(&sigcantmask, &l->l_sigmask); /* Check for pending signals when sleeping. */ if (sigispending(l, 0)) { lwp_lock(l); l->l_flag |= LW_PENDSIG; lwp_unlock(l); } mutex_exit(p->p_lock); } void sigsuspendteardown(struct lwp *l) { struct proc *p = l->l_proc; mutex_enter(p->p_lock); /* Check for pending signals when sleeping. */ if (l->l_sigrestore) { if (sigispending(l, 0)) { lwp_lock(l); l->l_flag |= LW_PENDSIG; lwp_unlock(l); } else { l->l_sigrestore = 0; l->l_sigmask = l->l_sigoldmask; } } mutex_exit(p->p_lock); } int sigsuspend1(struct lwp *l, const sigset_t *ss) { if (ss) sigsuspendsetup(l, ss); while (kpause("pause", true, 0, NULL) == 0) ; /* always return EINTR rather than ERESTART... */ return EINTR; } int sigaltstack1(struct lwp *l, const struct sigaltstack *nss, struct sigaltstack *oss) { struct proc *p = l->l_proc; int error = 0; mutex_enter(p->p_lock); if (oss) *oss = l->l_sigstk; if (nss) { if (nss->ss_flags & ~SS_ALLBITS) error = EINVAL; else if (nss->ss_flags & SS_DISABLE) { if (l->l_sigstk.ss_flags & SS_ONSTACK) error = EINVAL; } else if (nss->ss_size < MINSIGSTKSZ) error = ENOMEM; if (!error) l->l_sigstk = *nss; } mutex_exit(p->p_lock); return error; } int sigtimedwait1(struct lwp *l, const struct sys_____sigtimedwait50_args *uap, register_t *retval, copyin_t fetchss, copyout_t storeinf, copyin_t fetchts, copyout_t storets) { /* { syscallarg(const sigset_t *) set; syscallarg(siginfo_t *) info; syscallarg(struct timespec *) timeout; } */ struct proc *p = l->l_proc; int error, signum, timo; struct timespec ts, tsstart, tsnow; ksiginfo_t ksi; /* * Calculate timeout, if it was specified. * * NULL pointer means an infinite timeout. * {.tv_sec = 0, .tv_nsec = 0} means do not block. */ if (SCARG(uap, timeout)) { error = (*fetchts)(SCARG(uap, timeout), &ts, sizeof(ts)); if (error) return error; if ((error = itimespecfix(&ts)) != 0) return error; timo = tstohz(&ts); if (timo == 0) { if (ts.tv_sec == 0 && ts.tv_nsec == 0) timo = -1; /* do not block */ else timo = 1; /* the shortest possible timeout */ } /* * Remember current uptime, it would be used in * ECANCELED/ERESTART case. */ getnanouptime(&tsstart); } else { memset(&tsstart, 0, sizeof(tsstart)); /* XXXgcc */ timo = 0; /* infinite timeout */ } error = (*fetchss)(SCARG(uap, set), &l->l_sigwaitset, sizeof(l->l_sigwaitset)); if (error) return error; /* * Silently ignore SA_CANTMASK signals. psignal1() would ignore * SA_CANTMASK signals in waitset, we do this only for the below * siglist check. */ sigminusset(&sigcantmask, &l->l_sigwaitset); memset(&ksi.ksi_info, 0, sizeof(ksi.ksi_info)); mutex_enter(p->p_lock); /* Check for pending signals in the process, if no - then in LWP. */ if ((signum = sigget(&p->p_sigpend, &ksi, 0, &l->l_sigwaitset)) == 0) signum = sigget(&l->l_sigpend, &ksi, 0, &l->l_sigwaitset); if (signum != 0) { /* If found a pending signal, just copy it out to the user. */ mutex_exit(p->p_lock); goto out; } if (timo < 0) { /* If not allowed to block, return an error */ mutex_exit(p->p_lock); return EAGAIN; } /* * Set up the sigwait list and wait for signal to arrive. * We can either be woken up or time out. */ l->l_sigwaited = &ksi; LIST_INSERT_HEAD(&p->p_sigwaiters, l, l_sigwaiter); error = cv_timedwait_sig(&l->l_sigcv, p->p_lock, timo); /* * Need to find out if we woke as a result of _lwp_wakeup() or a * signal outside our wait set. */ if (l->l_sigwaited != NULL) { if (error == EINTR) { /* Wakeup via _lwp_wakeup(). */ error = ECANCELED; } else if (!error) { /* Spurious wakeup - arrange for syscall restart. */ error = ERESTART; } l->l_sigwaited = NULL; LIST_REMOVE(l, l_sigwaiter); } mutex_exit(p->p_lock); /* * If the sleep was interrupted (either by signal or wakeup), update * the timeout and copyout new value back. It would be used when * the syscall would be restarted or called again. */ if (timo && (error == ERESTART || error == ECANCELED)) { getnanouptime(&tsnow); /* Compute how much time has passed since start. */ timespecsub(&tsnow, &tsstart, &tsnow); /* Substract passed time from timeout. */ timespecsub(&ts, &tsnow, &ts); if (ts.tv_sec < 0) error = EAGAIN; else { /* Copy updated timeout to userland. */ error = (*storets)(&ts, SCARG(uap, timeout), sizeof(ts)); } } out: /* * If a signal from the wait set arrived, copy it to userland. * Copy only the used part of siginfo, the padding part is * left unchanged (userland is not supposed to touch it anyway). */ if (error == 0 && SCARG(uap, info)) { error = (*storeinf)(&ksi.ksi_info, SCARG(uap, info), sizeof(ksi.ksi_info)); } if (error == 0) { *retval = ksi.ksi_info._signo; SDT_PROBE(proc, kernel, , signal__clear, *retval, &ksi, 0, 0, 0); } return error; }