1 /* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_sig.c 8.7 (Berkeley) 4/18/94 35 * $FreeBSD: src/sys/kern/kern_sig.c,v 1.72.2.17 2003/05/16 16:34:34 obrien Exp $ 36 */ 37 38 #include "opt_ktrace.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/sysmsg.h> 44 #include <sys/signalvar.h> 45 #include <sys/resourcevar.h> 46 #include <sys/vnode.h> 47 #include <sys/event.h> 48 #include <sys/proc.h> 49 #include <sys/nlookup.h> 50 #include <sys/pioctl.h> 51 #include <sys/acct.h> 52 #include <sys/fcntl.h> 53 #include <sys/lock.h> 54 #include <sys/wait.h> 55 #include <sys/ktrace.h> 56 #include <sys/syslog.h> 57 #include <sys/stat.h> 58 #include <sys/sysent.h> 59 #include <sys/sysctl.h> 60 #include <sys/malloc.h> 61 #include <sys/interrupt.h> 62 #include <sys/unistd.h> 63 #include <sys/kern_syscall.h> 64 #include <sys/vkernel.h> 65 66 #include <sys/signal2.h> 67 #include <sys/thread2.h> 68 #include <sys/spinlock2.h> 69 70 #include <machine/cpu.h> 71 #include <machine/smp.h> 72 73 static int coredump(struct lwp *, int); 74 static char *expand_name(const char *, uid_t, pid_t); 75 static int dokillpg(int sig, int pgid, int all); 76 static int sig_ffs(sigset_t *set); 77 static int sigprop(int sig); 78 static void lwp_signotify(struct lwp *lp); 79 static void lwp_signotify_remote(void *arg); 80 static int kern_sigtimedwait(sigset_t set, siginfo_t *info, 81 struct timespec *timeout); 82 static void proc_stopwait(struct proc *p); 83 84 static int filt_sigattach(struct knote *kn); 85 static void filt_sigdetach(struct knote *kn); 86 static int filt_signal(struct knote *kn, long hint); 87 88 struct filterops sig_filtops = 89 { FILTEROP_MPSAFE, filt_sigattach, filt_sigdetach, filt_signal }; 90 91 static int kern_logsigexit = 1; 92 SYSCTL_INT(_kern, KERN_LOGSIGEXIT, logsigexit, CTLFLAG_RW, 93 &kern_logsigexit, 0, 94 "Log processes quitting on abnormal signals to syslog(3)"); 95 96 /* 97 * Can process p send the signal sig to process q? Only processes within 98 * the current reaper or children of the current reaper can be signaled. 99 * Normally the reaper itself cannot be signalled, unless initok is set. 100 */ 101 #define CANSIGNAL(q, sig, initok) \ 102 ((!p_trespass(curproc->p_ucred, (q)->p_ucred) && \ 103 reaper_sigtest(curproc, p, initok)) || \ 104 ((sig) == SIGCONT && (q)->p_session == curproc->p_session)) 105 106 /* 107 * Policy -- Can real uid ruid with ucred uc send a signal to process q? 108 */ 109 #define CANSIGIO(ruid, uc, q) \ 110 ((uc)->cr_uid == 0 || \ 111 (ruid) == (q)->p_ucred->cr_ruid || \ 112 (uc)->cr_uid == (q)->p_ucred->cr_ruid || \ 113 (ruid) == (q)->p_ucred->cr_uid || \ 114 (uc)->cr_uid == (q)->p_ucred->cr_uid) 115 116 int sugid_coredump; 117 SYSCTL_INT(_kern, OID_AUTO, sugid_coredump, CTLFLAG_RW, 118 &sugid_coredump, 0, "Enable coredumping set user/group ID processes"); 119 120 static int do_coredump = 1; 121 SYSCTL_INT(_kern, OID_AUTO, coredump, CTLFLAG_RW, 122 &do_coredump, 0, "Enable/Disable coredumps"); 123 124 /* 125 * Signal properties and actions. 126 * The array below categorizes the signals and their default actions 127 * according to the following properties: 128 */ 129 #define SA_KILL 0x01 /* terminates process by default */ 130 #define SA_CORE 0x02 /* ditto and coredumps */ 131 #define SA_STOP 0x04 /* suspend process */ 132 #define SA_TTYSTOP 0x08 /* ditto, from tty */ 133 #define SA_IGNORE 0x10 /* ignore by default */ 134 #define SA_CONT 0x20 /* continue if suspended */ 135 #define SA_CANTMASK 0x40 /* non-maskable, catchable */ 136 #define SA_CKPT 0x80 /* checkpoint process */ 137 138 139 static int sigproptbl[NSIG] = { 140 SA_KILL, /* SIGHUP */ 141 SA_KILL, /* SIGINT */ 142 SA_KILL|SA_CORE, /* SIGQUIT */ 143 SA_KILL|SA_CORE, /* SIGILL */ 144 SA_KILL|SA_CORE, /* SIGTRAP */ 145 SA_KILL|SA_CORE, /* SIGABRT */ 146 SA_KILL|SA_CORE, /* SIGEMT */ 147 SA_KILL|SA_CORE, /* SIGFPE */ 148 SA_KILL, /* SIGKILL */ 149 SA_KILL|SA_CORE, /* SIGBUS */ 150 SA_KILL|SA_CORE, /* SIGSEGV */ 151 SA_KILL|SA_CORE, /* SIGSYS */ 152 SA_KILL, /* SIGPIPE */ 153 SA_KILL, /* SIGALRM */ 154 SA_KILL, /* SIGTERM */ 155 SA_IGNORE, /* SIGURG */ 156 SA_STOP, /* SIGSTOP */ 157 SA_STOP|SA_TTYSTOP, /* SIGTSTP */ 158 SA_IGNORE|SA_CONT, /* SIGCONT */ 159 SA_IGNORE, /* SIGCHLD */ 160 SA_STOP|SA_TTYSTOP, /* SIGTTIN */ 161 SA_STOP|SA_TTYSTOP, /* SIGTTOU */ 162 SA_IGNORE, /* SIGIO */ 163 SA_KILL, /* SIGXCPU */ 164 SA_KILL, /* SIGXFSZ */ 165 SA_KILL, /* SIGVTALRM */ 166 SA_KILL, /* SIGPROF */ 167 SA_IGNORE, /* SIGWINCH */ 168 SA_IGNORE, /* SIGINFO */ 169 SA_KILL, /* SIGUSR1 */ 170 SA_KILL, /* SIGUSR2 */ 171 SA_IGNORE, /* SIGTHR */ 172 SA_CKPT, /* SIGCKPT */ 173 SA_KILL|SA_CKPT, /* SIGCKPTEXIT */ 174 SA_IGNORE, 175 SA_IGNORE, 176 SA_IGNORE, 177 SA_IGNORE, 178 SA_IGNORE, 179 SA_IGNORE, 180 SA_IGNORE, 181 SA_IGNORE, 182 SA_IGNORE, 183 SA_IGNORE, 184 SA_IGNORE, 185 SA_IGNORE, 186 SA_IGNORE, 187 SA_IGNORE, 188 SA_IGNORE, 189 SA_IGNORE, 190 SA_IGNORE, 191 SA_IGNORE, 192 SA_IGNORE, 193 SA_IGNORE, 194 SA_IGNORE, 195 SA_IGNORE, 196 SA_IGNORE, 197 SA_IGNORE, 198 SA_IGNORE, 199 SA_IGNORE, 200 SA_IGNORE, 201 SA_IGNORE, 202 SA_IGNORE, 203 SA_IGNORE, 204 }; 205 206 __read_mostly sigset_t sigcantmask_mask; 207 208 static __inline int 209 sigprop(int sig) 210 { 211 212 if (sig > 0 && sig < NSIG) 213 return (sigproptbl[_SIG_IDX(sig)]); 214 215 return (0); 216 } 217 218 static __inline int 219 sig_ffs(sigset_t *set) 220 { 221 int i; 222 223 for (i = 0; i < _SIG_WORDS; i++) 224 if (set->__bits[i]) 225 return (ffs(set->__bits[i]) + (i * 32)); 226 return (0); 227 } 228 229 /* 230 * Allows us to populate siginfo->si_pid and si_uid in the target process 231 * (p) from the originating thread (td). This function must work properly 232 * even if a kernel thread is sending the signal. 233 * 234 * NOTE: Signals are not queued, so if multiple signals are received the 235 * signal handler will only see the most recent pid and uid for any 236 * given signal number. 237 */ 238 static __inline void 239 sigsetfrompid(thread_t td, struct proc *p, int sig) 240 { 241 struct sigacts *sap; 242 243 if ((sap = p->p_sigacts) == NULL) 244 return; 245 if (td->td_proc) { 246 sap->ps_frominfo[sig].pid = td->td_proc->p_pid; 247 sap->ps_frominfo[sig].uid = td->td_ucred->cr_uid; 248 } else { 249 sap->ps_frominfo[sig].pid = 0; 250 sap->ps_frominfo[sig].uid = 0; 251 } 252 } 253 254 /* 255 * No requirements. 256 */ 257 int 258 kern_sigaction(int sig, struct sigaction *act, struct sigaction *oact) 259 { 260 struct thread *td = curthread; 261 struct proc *p = td->td_proc; 262 struct lwp *lp; 263 struct sigacts *ps = p->p_sigacts; 264 265 if (sig <= 0 || sig >= _SIG_MAXSIG) 266 return (EINVAL); 267 268 lwkt_gettoken(&p->p_token); 269 270 if (oact) { 271 oact->sa_handler = ps->ps_sigact[_SIG_IDX(sig)]; 272 oact->sa_mask = ps->ps_catchmask[_SIG_IDX(sig)]; 273 oact->sa_flags = 0; 274 if (SIGISMEMBER(ps->ps_sigonstack, sig)) 275 oact->sa_flags |= SA_ONSTACK; 276 if (!SIGISMEMBER(ps->ps_sigintr, sig)) 277 oact->sa_flags |= SA_RESTART; 278 if (SIGISMEMBER(ps->ps_sigreset, sig)) 279 oact->sa_flags |= SA_RESETHAND; 280 if (SIGISMEMBER(ps->ps_signodefer, sig)) 281 oact->sa_flags |= SA_NODEFER; 282 if (SIGISMEMBER(ps->ps_siginfo, sig)) 283 oact->sa_flags |= SA_SIGINFO; 284 if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDSTOP) 285 oact->sa_flags |= SA_NOCLDSTOP; 286 if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDWAIT) 287 oact->sa_flags |= SA_NOCLDWAIT; 288 } 289 if (act) { 290 /* 291 * Check for invalid requests. KILL and STOP cannot be 292 * caught. 293 */ 294 if (sig == SIGKILL || sig == SIGSTOP) { 295 if (act->sa_handler != SIG_DFL) { 296 lwkt_reltoken(&p->p_token); 297 return (EINVAL); 298 } 299 } 300 301 /* 302 * Change setting atomically. 303 */ 304 ps->ps_catchmask[_SIG_IDX(sig)] = act->sa_mask; 305 SIG_CANTMASK(ps->ps_catchmask[_SIG_IDX(sig)]); 306 if (act->sa_flags & SA_SIGINFO) { 307 ps->ps_sigact[_SIG_IDX(sig)] = 308 (__sighandler_t *)act->sa_sigaction; 309 SIGADDSET(ps->ps_siginfo, sig); 310 } else { 311 ps->ps_sigact[_SIG_IDX(sig)] = act->sa_handler; 312 SIGDELSET(ps->ps_siginfo, sig); 313 } 314 if (!(act->sa_flags & SA_RESTART)) 315 SIGADDSET(ps->ps_sigintr, sig); 316 else 317 SIGDELSET(ps->ps_sigintr, sig); 318 if (act->sa_flags & SA_ONSTACK) 319 SIGADDSET(ps->ps_sigonstack, sig); 320 else 321 SIGDELSET(ps->ps_sigonstack, sig); 322 if (act->sa_flags & SA_RESETHAND) 323 SIGADDSET(ps->ps_sigreset, sig); 324 else 325 SIGDELSET(ps->ps_sigreset, sig); 326 if (act->sa_flags & SA_NODEFER) 327 SIGADDSET(ps->ps_signodefer, sig); 328 else 329 SIGDELSET(ps->ps_signodefer, sig); 330 if (sig == SIGCHLD) { 331 if (act->sa_flags & SA_NOCLDSTOP) 332 p->p_sigacts->ps_flag |= PS_NOCLDSTOP; 333 else 334 p->p_sigacts->ps_flag &= ~PS_NOCLDSTOP; 335 if (act->sa_flags & SA_NOCLDWAIT) { 336 /* 337 * Paranoia: since SA_NOCLDWAIT is implemented 338 * by reparenting the dying child to PID 1 (and 339 * trust it to reap the zombie), PID 1 itself 340 * is forbidden to set SA_NOCLDWAIT. 341 */ 342 if (p->p_pid == 1) 343 p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT; 344 else 345 p->p_sigacts->ps_flag |= PS_NOCLDWAIT; 346 } else { 347 p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT; 348 } 349 if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN) 350 ps->ps_flag |= PS_CLDSIGIGN; 351 else 352 ps->ps_flag &= ~PS_CLDSIGIGN; 353 } 354 /* 355 * Set bit in p_sigignore for signals that are set to SIG_IGN, 356 * and for signals set to SIG_DFL where the default is to 357 * ignore. However, don't put SIGCONT in p_sigignore, as we 358 * have to restart the process. 359 * 360 * Also remove the signal from the process and lwp signal 361 * list. 362 */ 363 if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN || 364 (sigprop(sig) & SA_IGNORE && 365 ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)) { 366 SIGDELSET_ATOMIC(p->p_siglist, sig); 367 FOREACH_LWP_IN_PROC(lp, p) { 368 spin_lock(&lp->lwp_spin); 369 SIGDELSET(lp->lwp_siglist, sig); 370 spin_unlock(&lp->lwp_spin); 371 } 372 if (sig != SIGCONT) { 373 /* easier in ksignal */ 374 SIGADDSET(p->p_sigignore, sig); 375 } 376 SIGDELSET(p->p_sigcatch, sig); 377 } else { 378 SIGDELSET(p->p_sigignore, sig); 379 if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL) 380 SIGDELSET(p->p_sigcatch, sig); 381 else 382 SIGADDSET(p->p_sigcatch, sig); 383 } 384 } 385 lwkt_reltoken(&p->p_token); 386 return (0); 387 } 388 389 int 390 sys_sigaction(struct sysmsg *sysmsg, const struct sigaction_args *uap) 391 { 392 struct sigaction act, oact; 393 struct sigaction *actp, *oactp; 394 int error; 395 396 actp = (uap->act != NULL) ? &act : NULL; 397 oactp = (uap->oact != NULL) ? &oact : NULL; 398 if (actp) { 399 error = copyin(uap->act, actp, sizeof(act)); 400 if (error) 401 return (error); 402 } 403 error = kern_sigaction(uap->sig, actp, oactp); 404 if (oactp && !error) { 405 error = copyout(oactp, uap->oact, sizeof(oact)); 406 } 407 return (error); 408 } 409 410 /* 411 * Initialize signal state for process 0; 412 * set to ignore signals that are ignored by default. 413 */ 414 void 415 siginit(struct proc *p) 416 { 417 int i; 418 419 for (i = 1; i <= NSIG; i++) { 420 if (sigprop(i) & SA_IGNORE && i != SIGCONT) 421 SIGADDSET(p->p_sigignore, i); 422 } 423 424 /* 425 * Also initialize signal-related global state. 426 */ 427 SIGSETOR_CANTMASK(sigcantmask_mask); 428 } 429 430 /* 431 * Reset signals for an exec of the specified process. 432 */ 433 void 434 execsigs(struct proc *p) 435 { 436 struct sigacts *ps = p->p_sigacts; 437 struct lwp *lp; 438 int sig; 439 440 lp = ONLY_LWP_IN_PROC(p); 441 442 /* 443 * Reset caught signals. Held signals remain held 444 * through p_sigmask (unless they were caught, 445 * and are now ignored by default). 446 */ 447 while (SIGNOTEMPTY(p->p_sigcatch)) { 448 sig = sig_ffs(&p->p_sigcatch); 449 SIGDELSET(p->p_sigcatch, sig); 450 if (sigprop(sig) & SA_IGNORE) { 451 if (sig != SIGCONT) 452 SIGADDSET(p->p_sigignore, sig); 453 SIGDELSET_ATOMIC(p->p_siglist, sig); 454 /* don't need spinlock */ 455 SIGDELSET(lp->lwp_siglist, sig); 456 } 457 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL; 458 } 459 460 /* 461 * Reset stack state to the user stack. 462 * Clear set of signals caught on the signal stack. 463 */ 464 lp->lwp_sigstk.ss_flags = SS_DISABLE; 465 lp->lwp_sigstk.ss_size = 0; 466 lp->lwp_sigstk.ss_sp = NULL; 467 lp->lwp_flags &= ~LWP_ALTSTACK; 468 /* 469 * Reset no zombies if child dies flag as Solaris does. 470 */ 471 p->p_sigacts->ps_flag &= ~(PS_NOCLDWAIT | PS_CLDSIGIGN); 472 if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN) 473 ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL; 474 } 475 476 /* 477 * kern_sigprocmask() - MP SAFE ONLY IF p == curproc 478 * 479 * Manipulate signal mask. This routine is MP SAFE *ONLY* if 480 * p == curproc. 481 */ 482 int 483 kern_sigprocmask(int how, sigset_t *set, sigset_t *oset) 484 { 485 struct thread *td = curthread; 486 struct lwp *lp = td->td_lwp; 487 struct proc *p = td->td_proc; 488 int error; 489 490 lwkt_gettoken(&p->p_token); 491 492 if (oset != NULL) 493 *oset = lp->lwp_sigmask; 494 495 error = 0; 496 if (set != NULL) { 497 switch (how) { 498 case SIG_BLOCK: 499 SIG_CANTMASK(*set); 500 SIGSETOR(lp->lwp_sigmask, *set); 501 break; 502 case SIG_UNBLOCK: 503 SIGSETNAND(lp->lwp_sigmask, *set); 504 break; 505 case SIG_SETMASK: 506 SIG_CANTMASK(*set); 507 lp->lwp_sigmask = *set; 508 break; 509 default: 510 error = EINVAL; 511 break; 512 } 513 } 514 515 lwkt_reltoken(&p->p_token); 516 517 return (error); 518 } 519 520 /* 521 * sigprocmask() 522 * 523 * MPSAFE 524 */ 525 int 526 sys_sigprocmask(struct sysmsg *sysmsg, const struct sigprocmask_args *uap) 527 { 528 sigset_t set, oset; 529 sigset_t *setp, *osetp; 530 int error; 531 532 setp = (uap->set != NULL) ? &set : NULL; 533 osetp = (uap->oset != NULL) ? &oset : NULL; 534 if (setp) { 535 error = copyin(uap->set, setp, sizeof(set)); 536 if (error) 537 return (error); 538 } 539 error = kern_sigprocmask(uap->how, setp, osetp); 540 if (osetp && !error) { 541 error = copyout(osetp, uap->oset, sizeof(oset)); 542 } 543 return (error); 544 } 545 546 /* 547 * MPSAFE 548 */ 549 int 550 kern_sigpending(sigset_t *set) 551 { 552 struct lwp *lp = curthread->td_lwp; 553 554 *set = lwp_sigpend(lp); 555 556 return (0); 557 } 558 559 /* 560 * MPSAFE 561 */ 562 int 563 sys_sigpending(struct sysmsg *sysmsg, const struct sigpending_args *uap) 564 { 565 sigset_t set; 566 int error; 567 568 error = kern_sigpending(&set); 569 570 if (error == 0) 571 error = copyout(&set, uap->set, sizeof(set)); 572 return (error); 573 } 574 575 /* 576 * Suspend process until signal, providing mask to be set 577 * in the meantime. 578 * 579 * MPSAFE 580 */ 581 int 582 kern_sigsuspend(sigset_t *set) 583 { 584 struct thread *td = curthread; 585 struct lwp *lp = td->td_lwp; 586 struct proc *p = td->td_proc; 587 struct sigacts *ps = p->p_sigacts; 588 589 /* 590 * When returning from sigsuspend, we want 591 * the old mask to be restored after the 592 * signal handler has finished. Thus, we 593 * save it here and mark the sigacts structure 594 * to indicate this. 595 */ 596 lp->lwp_oldsigmask = lp->lwp_sigmask; 597 lp->lwp_flags |= LWP_OLDMASK; 598 599 SIG_CANTMASK(*set); 600 lp->lwp_sigmask = *set; 601 while (tsleep(ps, PCATCH, "pause", 0) == 0) 602 /* void */; 603 /* always return EINTR rather than ERESTART... */ 604 return (EINTR); 605 } 606 607 /* 608 * Note nonstandard calling convention: libc stub passes mask, not 609 * pointer, to save a copyin. 610 * 611 * MPSAFE 612 */ 613 int 614 sys_sigsuspend(struct sysmsg *sysmsg, const struct sigsuspend_args *uap) 615 { 616 sigset_t mask; 617 int error; 618 619 error = copyin(uap->sigmask, &mask, sizeof(mask)); 620 if (error) 621 return (error); 622 623 error = kern_sigsuspend(&mask); 624 625 return (error); 626 } 627 628 /* 629 * MPSAFE 630 */ 631 int 632 kern_sigaltstack(stack_t *ss, stack_t *oss) 633 { 634 struct thread *td = curthread; 635 struct lwp *lp = td->td_lwp; 636 struct proc *p = td->td_proc; 637 638 if ((lp->lwp_flags & LWP_ALTSTACK) == 0) 639 lp->lwp_sigstk.ss_flags |= SS_DISABLE; 640 641 if (oss) 642 *oss = lp->lwp_sigstk; 643 644 if (ss) { 645 if (ss->ss_flags & ~SS_DISABLE) 646 return (EINVAL); 647 if (ss->ss_flags & SS_DISABLE) { 648 if (lp->lwp_sigstk.ss_flags & SS_ONSTACK) 649 return (EPERM); 650 lp->lwp_flags &= ~LWP_ALTSTACK; 651 lp->lwp_sigstk.ss_flags = ss->ss_flags; 652 } else { 653 if (ss->ss_size < p->p_sysent->sv_minsigstksz) 654 return (ENOMEM); 655 lp->lwp_flags |= LWP_ALTSTACK; 656 lp->lwp_sigstk = *ss; 657 } 658 } 659 660 return (0); 661 } 662 663 /* 664 * MPSAFE 665 */ 666 int 667 sys_sigaltstack(struct sysmsg *sysmsg, const struct sigaltstack_args *uap) 668 { 669 stack_t ss, oss; 670 int error; 671 672 if (uap->ss) { 673 error = copyin(uap->ss, &ss, sizeof(ss)); 674 if (error) 675 return (error); 676 } 677 678 error = kern_sigaltstack(uap->ss ? &ss : NULL, uap->oss ? &oss : NULL); 679 680 if (error == 0 && uap->oss) 681 error = copyout(&oss, uap->oss, sizeof(*uap->oss)); 682 return (error); 683 } 684 685 /* 686 * Common code for kill process group/broadcast kill. 687 * cp is calling process. 688 */ 689 struct killpg_info { 690 int nfound; 691 int sig; 692 }; 693 694 static int killpg_all_callback(struct proc *p, void *data); 695 696 static int 697 dokillpg(int sig, int pgid, int all) 698 { 699 struct killpg_info info; 700 struct proc *cp = curproc; 701 struct proc *p; 702 struct pgrp *pgrp; 703 704 info.nfound = 0; 705 info.sig = sig; 706 707 if (all) { 708 /* 709 * broadcast 710 */ 711 allproc_scan(killpg_all_callback, &info, 0); 712 } else { 713 if (pgid == 0) { 714 /* 715 * zero pgid means send to my process group. 716 */ 717 pgrp = cp->p_pgrp; 718 pgref(pgrp); 719 } else { 720 pgrp = pgfind(pgid); 721 if (pgrp == NULL) 722 return (ESRCH); 723 } 724 725 /* 726 * Must interlock all signals against fork 727 */ 728 lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE); 729 LIST_FOREACH(p, &pgrp->pg_members, p_pglist) { 730 if (p->p_pid <= 1 || 731 p->p_stat == SZOMB || 732 (p->p_flags & P_SYSTEM) || 733 !CANSIGNAL(p, sig, 0)) { 734 continue; 735 } 736 ++info.nfound; 737 if (sig) 738 ksignal(p, sig); 739 } 740 lockmgr(&pgrp->pg_lock, LK_RELEASE); 741 pgrel(pgrp); 742 } 743 return (info.nfound ? 0 : ESRCH); 744 } 745 746 static int 747 killpg_all_callback(struct proc *p, void *data) 748 { 749 struct killpg_info *info = data; 750 751 if (p->p_pid <= 1 || (p->p_flags & P_SYSTEM) || 752 p == curproc || !CANSIGNAL(p, info->sig, 0)) { 753 return (0); 754 } 755 ++info->nfound; 756 if (info->sig) 757 ksignal(p, info->sig); 758 return(0); 759 } 760 761 /* 762 * Send a general signal to a process or LWPs within that process. 763 * 764 * Note that new signals cannot be sent if a process is exiting or already 765 * a zombie, but we return success anyway as userland is likely to not handle 766 * the race properly. 767 * 768 * No requirements. 769 */ 770 int 771 kern_kill(int sig, pid_t pid, lwpid_t tid) 772 { 773 int t; 774 775 if ((u_int)sig >= _SIG_MAXSIG) 776 return (EINVAL); 777 778 if (pid > 0) { 779 struct proc *p; 780 struct lwp *lp = NULL; 781 782 /* 783 * Sending a signal to pid 1 as root requires that we 784 * are not reboot-restricted. 785 */ 786 if (pid == 1 && caps_priv_check_self(SYSCAP_NOREBOOT)) 787 return EPERM; 788 789 /* 790 * Send a signal to a single process. If the kill() is 791 * racing an exiting process which has not yet been reaped 792 * act as though the signal was delivered successfully but 793 * don't actually try to deliver the signal. 794 */ 795 if ((p = pfind(pid)) == NULL) { 796 if ((p = zpfind(pid)) == NULL) 797 return (ESRCH); 798 PRELE(p); 799 return (0); 800 } 801 if (p != curproc) { 802 lwkt_gettoken_shared(&p->p_token); 803 if (!CANSIGNAL(p, sig, 1)) { 804 lwkt_reltoken(&p->p_token); 805 PRELE(p); 806 return (EPERM); 807 } 808 lwkt_reltoken(&p->p_token); 809 } 810 811 /* 812 * NOP if the process is exiting. Note that lwpsignal() is 813 * called directly with P_WEXIT set to kill individual LWPs 814 * during exit, which is allowed. 815 */ 816 if (p->p_flags & P_WEXIT) { 817 PRELE(p); 818 return (0); 819 } 820 if (tid != -1) { 821 lwkt_gettoken_shared(&p->p_token); 822 lp = lwp_rb_tree_RB_LOOKUP(&p->p_lwp_tree, tid); 823 if (lp == NULL) { 824 lwkt_reltoken(&p->p_token); 825 PRELE(p); 826 return (ESRCH); 827 } 828 LWPHOLD(lp); 829 lwkt_reltoken(&p->p_token); 830 } 831 if (sig) 832 lwpsignal(p, lp, sig); 833 if (lp) 834 LWPRELE(lp); 835 PRELE(p); 836 837 return (0); 838 } 839 840 /* 841 * If we come here, pid is a special broadcast pid. 842 * This doesn't mix with a tid. 843 */ 844 if (tid != -1) 845 return (EINVAL); 846 847 switch (pid) { 848 case -1: /* broadcast signal */ 849 t = (dokillpg(sig, 0, 1)); 850 break; 851 case 0: /* signal own process group */ 852 t = (dokillpg(sig, 0, 0)); 853 break; 854 default: /* negative explicit process group */ 855 t = (dokillpg(sig, -pid, 0)); 856 break; 857 } 858 return t; 859 } 860 861 int 862 sys_kill(struct sysmsg *sysmsg, const struct kill_args *uap) 863 { 864 int error; 865 866 error = kern_kill(uap->signum, uap->pid, -1); 867 return (error); 868 } 869 870 int 871 sys_lwp_kill(struct sysmsg *sysmsg, const struct lwp_kill_args *uap) 872 { 873 int error; 874 pid_t pid = uap->pid; 875 876 /* 877 * A tid is mandatory for lwp_kill(), otherwise 878 * you could simply use kill(). 879 */ 880 if (uap->tid == -1) 881 return (EINVAL); 882 883 /* 884 * To save on a getpid() function call for intra-process 885 * signals, pid == -1 means current process. 886 */ 887 if (pid == -1) 888 pid = curproc->p_pid; 889 890 error = kern_kill(uap->signum, pid, uap->tid); 891 return (error); 892 } 893 894 /* 895 * Send a signal to a process group. 896 */ 897 void 898 gsignal(int pgid, int sig) 899 { 900 struct pgrp *pgrp; 901 902 if (pgid && (pgrp = pgfind(pgid))) 903 pgsignal(pgrp, sig, 0); 904 } 905 906 /* 907 * Send a signal to a process group. If checktty is 1, 908 * limit to members which have a controlling terminal. 909 * 910 * pg_lock interlocks against a fork that might be in progress, to 911 * ensure that the new child process picks up the signal. 912 */ 913 void 914 pgsignal(struct pgrp *pgrp, int sig, int checkctty) 915 { 916 struct proc *p; 917 918 /* 919 * Must interlock all signals against fork 920 */ 921 if (pgrp) { 922 pgref(pgrp); 923 lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE); 924 LIST_FOREACH(p, &pgrp->pg_members, p_pglist) { 925 if (checkctty == 0 || p->p_flags & P_CONTROLT) 926 ksignal(p, sig); 927 } 928 lockmgr(&pgrp->pg_lock, LK_RELEASE); 929 pgrel(pgrp); 930 } 931 } 932 933 /* 934 * Send a signal caused by a trap to the current lwp. If it will be caught 935 * immediately, deliver it with correct code. Otherwise, post it normally. 936 * 937 * These signals may ONLY be delivered to the specified lwp and may never 938 * be delivered to the process generically. 939 * 940 * lpmap->blockallsigs is ignored. 941 */ 942 void 943 trapsignal(struct lwp *lp, int sig, u_long code) 944 { 945 struct proc *p = lp->lwp_proc; 946 struct sigacts *ps = p->p_sigacts; 947 948 /* 949 * If we are a virtual kernel running an emulated user process 950 * context, switch back to the virtual kernel context before 951 * trying to post the signal. 952 */ 953 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 954 struct trapframe *tf = lp->lwp_md.md_regs; 955 tf->tf_trapno = 0; 956 vkernel_trap(lp, tf); 957 } 958 959 if ((p->p_flags & P_TRACED) == 0 && SIGISMEMBER(p->p_sigcatch, sig) && 960 !SIGISMEMBER(lp->lwp_sigmask, sig)) { 961 lp->lwp_ru.ru_nsignals++; 962 #ifdef KTRACE 963 if (KTRPOINT(lp->lwp_thread, KTR_PSIG)) 964 ktrpsig(lp, sig, ps->ps_sigact[_SIG_IDX(sig)], 965 &lp->lwp_sigmask, code); 966 #endif 967 (*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)], sig, 968 &lp->lwp_sigmask, code); 969 SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]); 970 if (!SIGISMEMBER(ps->ps_signodefer, sig)) 971 SIGADDSET(lp->lwp_sigmask, sig); 972 if (SIGISMEMBER(ps->ps_sigreset, sig)) { 973 /* 974 * See kern_sigaction() for origin of this code. 975 */ 976 SIGDELSET(p->p_sigcatch, sig); 977 if (sig != SIGCONT && 978 sigprop(sig) & SA_IGNORE) 979 SIGADDSET(p->p_sigignore, sig); 980 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL; 981 } 982 } else { 983 lp->lwp_code = code; /* XXX for core dump/debugger */ 984 lp->lwp_sig = sig; /* XXX to verify code */ 985 lwpsignal(p, lp, sig); 986 } 987 } 988 989 /* 990 * Find a suitable lwp to deliver the signal to. Returns NULL if all 991 * lwps hold the signal blocked. 992 * 993 * Caller must hold p->p_token. 994 * 995 * Returns a lp or NULL. If non-NULL the lp is held and its token is 996 * acquired. 997 */ 998 static struct lwp * 999 find_lwp_for_signal(struct proc *p, int sig) 1000 { 1001 struct lwp *lp; 1002 struct lwp *run, *sleep, *stop; 1003 1004 /* 1005 * If the running/preempted thread belongs to the proc to which 1006 * the signal is being delivered and this thread does not block 1007 * the signal, then we can avoid a context switch by delivering 1008 * the signal to this thread, because it will return to userland 1009 * soon anyways. 1010 */ 1011 lp = lwkt_preempted_proc(); 1012 if (lp != NULL && lp->lwp_proc == p) { 1013 LWPHOLD(lp); 1014 lwkt_gettoken(&lp->lwp_token); 1015 if (!SIGISMEMBER(lp->lwp_sigmask, sig)) { 1016 /* return w/ token held */ 1017 return (lp); 1018 } 1019 lwkt_reltoken(&lp->lwp_token); 1020 LWPRELE(lp); 1021 } 1022 1023 run = sleep = stop = NULL; 1024 FOREACH_LWP_IN_PROC(lp, p) { 1025 /* 1026 * If the signal is being blocked by the lwp, then this 1027 * lwp is not eligible for receiving the signal. 1028 */ 1029 LWPHOLD(lp); 1030 lwkt_gettoken(&lp->lwp_token); 1031 1032 if (SIGISMEMBER(lp->lwp_sigmask, sig)) { 1033 lwkt_reltoken(&lp->lwp_token); 1034 LWPRELE(lp); 1035 continue; 1036 } 1037 1038 switch (lp->lwp_stat) { 1039 case LSRUN: 1040 if (sleep) { 1041 lwkt_token_swap(); 1042 lwkt_reltoken(&sleep->lwp_token); 1043 LWPRELE(sleep); 1044 sleep = NULL; 1045 run = lp; 1046 } else if (stop) { 1047 lwkt_token_swap(); 1048 lwkt_reltoken(&stop->lwp_token); 1049 LWPRELE(stop); 1050 stop = NULL; 1051 run = lp; 1052 } else { 1053 run = lp; 1054 } 1055 break; 1056 case LSSLEEP: 1057 if (lp->lwp_flags & LWP_SINTR) { 1058 if (sleep) { 1059 lwkt_reltoken(&lp->lwp_token); 1060 LWPRELE(lp); 1061 } else if (stop) { 1062 lwkt_token_swap(); 1063 lwkt_reltoken(&stop->lwp_token); 1064 LWPRELE(stop); 1065 stop = NULL; 1066 sleep = lp; 1067 } else { 1068 sleep = lp; 1069 } 1070 } else { 1071 lwkt_reltoken(&lp->lwp_token); 1072 LWPRELE(lp); 1073 } 1074 break; 1075 case LSSTOP: 1076 if (sleep) { 1077 lwkt_reltoken(&lp->lwp_token); 1078 LWPRELE(lp); 1079 } else if (stop) { 1080 lwkt_reltoken(&lp->lwp_token); 1081 LWPRELE(lp); 1082 } else { 1083 stop = lp; 1084 } 1085 break; 1086 } 1087 if (run) 1088 break; 1089 } 1090 1091 if (run != NULL) 1092 return (run); 1093 else if (sleep != NULL) 1094 return (sleep); 1095 else 1096 return (stop); 1097 } 1098 1099 /* 1100 * Send the signal to the process. If the signal has an action, the action 1101 * is usually performed by the target process rather than the caller; we add 1102 * the signal to the set of pending signals for the process. 1103 * 1104 * Exceptions: 1105 * o When a stop signal is sent to a sleeping process that takes the 1106 * default action, the process is stopped without awakening it. 1107 * o SIGCONT restarts stopped processes (or puts them back to sleep) 1108 * regardless of the signal action (eg, blocked or ignored). 1109 * 1110 * Other ignored signals are discarded immediately. 1111 * 1112 * If the caller wishes to call this function from a hard code section the 1113 * caller must already hold p->p_token (see kern_clock.c). 1114 * 1115 * No requirements. 1116 */ 1117 void 1118 ksignal(struct proc *p, int sig) 1119 { 1120 lwpsignal(p, NULL, sig); 1121 } 1122 1123 /* 1124 * The core for ksignal. lp may be NULL, then a suitable thread 1125 * will be chosen. If not, lp MUST be a member of p. 1126 * 1127 * If the caller wishes to call this function from a hard code section the 1128 * caller must already hold p->p_token. 1129 * 1130 * No requirements. 1131 */ 1132 void 1133 lwpsignal(struct proc *p, struct lwp *lp, int sig) 1134 { 1135 struct proc *q; 1136 sig_t action; 1137 int prop; 1138 1139 if (sig >= _SIG_MAXSIG || sig <= 0) { 1140 kprintf("lwpsignal: signal %d\n", sig); 1141 panic("lwpsignal signal number"); 1142 } 1143 1144 KKASSERT(lp == NULL || lp->lwp_proc == p); 1145 1146 /* 1147 * We don't want to race... well, all sorts of things. Get appropriate 1148 * tokens. 1149 * 1150 * Don't try to deliver a generic signal to an exiting process, 1151 * the signal structures could be in flux. We check the LWP later 1152 * on. 1153 */ 1154 PHOLD(p); 1155 if (lp) { 1156 LWPHOLD(lp); 1157 lwkt_gettoken(&lp->lwp_token); 1158 } else { 1159 lwkt_gettoken(&p->p_token); 1160 if (p->p_flags & P_WEXIT) 1161 goto out; 1162 } 1163 1164 prop = sigprop(sig); 1165 1166 /* 1167 * If proc is traced, always give parent a chance; 1168 * if signal event is tracked by procfs, give *that* 1169 * a chance, as well. 1170 */ 1171 if ((p->p_flags & P_TRACED) || (p->p_stops & S_SIG)) { 1172 action = SIG_DFL; 1173 } else { 1174 /* 1175 * Do not try to deliver signals to an exiting lwp other 1176 * than SIGKILL. Note that we must still deliver the signal 1177 * if P_WEXIT is set in the process flags. 1178 */ 1179 if (lp && (lp->lwp_mpflags & LWP_MP_WEXIT) && sig != SIGKILL) { 1180 lwkt_reltoken(&lp->lwp_token); 1181 LWPRELE(lp); 1182 PRELE(p); 1183 return; 1184 } 1185 1186 /* 1187 * If the signal is being ignored, then we forget about 1188 * it immediately. NOTE: We don't set SIGCONT in p_sigignore, 1189 * and if it is set to SIG_IGN, action will be SIG_DFL here. 1190 */ 1191 if (SIGISMEMBER(p->p_sigignore, sig)) { 1192 /* 1193 * Even if a signal is set SIG_IGN, it may still be 1194 * lurking in a kqueue. 1195 */ 1196 KNOTE(&p->p_klist, NOTE_SIGNAL | sig); 1197 if (lp) { 1198 lwkt_reltoken(&lp->lwp_token); 1199 LWPRELE(lp); 1200 } else { 1201 lwkt_reltoken(&p->p_token); 1202 } 1203 PRELE(p); 1204 return; 1205 } 1206 if (SIGISMEMBER(p->p_sigcatch, sig)) 1207 action = SIG_CATCH; 1208 else 1209 action = SIG_DFL; 1210 } 1211 1212 /* 1213 * If continuing, clear any pending STOP signals for the whole 1214 * process. 1215 */ 1216 if (prop & SA_CONT) { 1217 lwkt_gettoken(&p->p_token); 1218 SIG_STOPSIGMASK_ATOMIC(p->p_siglist); 1219 lwkt_reltoken(&p->p_token); 1220 } 1221 1222 if (prop & SA_STOP) { 1223 /* 1224 * If sending a tty stop signal to a member of an orphaned 1225 * process group, discard the signal here if the action 1226 * is default; don't stop the process below if sleeping, 1227 * and don't clear any pending SIGCONT. 1228 */ 1229 if ((prop & SA_TTYSTOP) && p->p_pgrp->pg_jobc == 0 && 1230 action == SIG_DFL) { 1231 if (lp) { 1232 lwkt_reltoken(&lp->lwp_token); 1233 LWPRELE(lp); 1234 } else { 1235 lwkt_reltoken(&p->p_token); 1236 } 1237 PRELE(p); 1238 return; 1239 } 1240 lwkt_gettoken(&p->p_token); 1241 SIG_CONTSIGMASK_ATOMIC(p->p_siglist); 1242 p->p_flags &= ~P_CONTINUED; 1243 lwkt_reltoken(&p->p_token); 1244 } 1245 1246 if (p->p_stat == SSTOP) { 1247 /* 1248 * Nobody can handle this signal, add it to the lwp or 1249 * process pending list 1250 */ 1251 lwkt_gettoken(&p->p_token); 1252 if (p->p_stat != SSTOP) { 1253 lwkt_reltoken(&p->p_token); 1254 goto not_stopped; 1255 } 1256 sigsetfrompid(curthread, p, sig); 1257 if (lp) { 1258 spin_lock(&lp->lwp_spin); 1259 SIGADDSET(lp->lwp_siglist, sig); 1260 spin_unlock(&lp->lwp_spin); 1261 } else { 1262 SIGADDSET_ATOMIC(p->p_siglist, sig); 1263 } 1264 1265 /* 1266 * If the process is stopped and is being traced, then no 1267 * further action is necessary. 1268 */ 1269 if (p->p_flags & P_TRACED) { 1270 lwkt_reltoken(&p->p_token); 1271 goto out; 1272 } 1273 1274 /* 1275 * If the process is stopped and receives a KILL signal, 1276 * make the process runnable. 1277 */ 1278 if (sig == SIGKILL) { 1279 proc_unstop(p, SSTOP); 1280 lwkt_reltoken(&p->p_token); 1281 goto active_process; 1282 } 1283 1284 /* 1285 * If the process is stopped and receives a CONT signal, 1286 * then try to make the process runnable again. 1287 */ 1288 if (prop & SA_CONT) { 1289 /* 1290 * If SIGCONT is default (or ignored), we continue the 1291 * process but don't leave the signal in p_siglist, as 1292 * it has no further action. If SIGCONT is held, we 1293 * continue the process and leave the signal in 1294 * p_siglist. If the process catches SIGCONT, let it 1295 * handle the signal itself. 1296 * 1297 * XXX what if the signal is being held blocked? 1298 * 1299 * Token required to interlock kern_wait(). 1300 * Reparenting can also cause a race so we have to 1301 * hold (q). 1302 */ 1303 q = p->p_pptr; 1304 PHOLD(q); 1305 lwkt_gettoken(&q->p_token); 1306 p->p_flags |= P_CONTINUED; 1307 wakeup(q); 1308 if (action == SIG_DFL) 1309 SIGDELSET_ATOMIC(p->p_siglist, sig); 1310 proc_unstop(p, SSTOP); 1311 lwkt_reltoken(&q->p_token); 1312 PRELE(q); 1313 lwkt_reltoken(&p->p_token); 1314 if (action == SIG_CATCH) 1315 goto active_process; 1316 goto out; 1317 } 1318 1319 /* 1320 * If the process is stopped and receives another STOP 1321 * signal, we do not need to stop it again. If we did 1322 * the shell could get confused. 1323 * 1324 * However, if the current/preempted lwp is part of the 1325 * process receiving the signal, we need to keep it, 1326 * so that this lwp can stop in issignal() later, as 1327 * we don't want to wait until it reaches userret! 1328 */ 1329 if (prop & SA_STOP) { 1330 if (lwkt_preempted_proc() == NULL || 1331 lwkt_preempted_proc()->lwp_proc != p) { 1332 SIGDELSET_ATOMIC(p->p_siglist, sig); 1333 } 1334 } 1335 1336 /* 1337 * Otherwise the process is stopped and it received some 1338 * signal, which does not change its stopped state. When 1339 * the process is continued a wakeup(p) will be issued which 1340 * will wakeup any threads sleeping in tstop(). 1341 */ 1342 lwkt_reltoken(&p->p_token); 1343 goto out; 1344 /* NOTREACHED */ 1345 } 1346 not_stopped: 1347 ; 1348 /* else not stopped */ 1349 active_process: 1350 1351 /* 1352 * Never deliver a lwp-specific signal to a random lwp. 1353 */ 1354 if (lp == NULL) { 1355 /* NOTE: returns lp w/ token held */ 1356 lp = find_lwp_for_signal(p, sig); 1357 if (lp) { 1358 if (SIGISMEMBER(lp->lwp_sigmask, sig)) { 1359 lwkt_reltoken(&lp->lwp_token); 1360 LWPRELE(lp); 1361 lp = NULL; 1362 /* maintain proc token */ 1363 } else { 1364 lwkt_token_swap(); 1365 lwkt_reltoken(&p->p_token); 1366 /* maintain lp token */ 1367 } 1368 } 1369 } 1370 1371 /* 1372 * Deliver to the process generically if (1) the signal is being 1373 * sent to any thread or (2) we could not find a thread to deliver 1374 * it to. 1375 */ 1376 if (lp == NULL) { 1377 sigsetfrompid(curthread, p, sig); 1378 KNOTE(&p->p_klist, NOTE_SIGNAL | sig); 1379 SIGADDSET_ATOMIC(p->p_siglist, sig); 1380 goto out; 1381 } 1382 1383 /* 1384 * Deliver to a specific LWP whether it masks it or not. It will 1385 * not be dispatched if masked but we must still deliver it. 1386 */ 1387 if (p->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) && 1388 (p->p_flags & P_TRACED) == 0) { 1389 lwkt_gettoken(&p->p_token); 1390 p->p_nice = NZERO; 1391 lwkt_reltoken(&p->p_token); 1392 } 1393 1394 /* 1395 * If the process receives a STOP signal which indeed needs to 1396 * stop the process, do so. If the process chose to catch the 1397 * signal, it will be treated like any other signal. 1398 */ 1399 if ((prop & SA_STOP) && action == SIG_DFL) { 1400 /* 1401 * If a child holding parent blocked, stopping 1402 * could cause deadlock. Take no action at this 1403 * time. 1404 */ 1405 lwkt_gettoken(&p->p_token); 1406 if (p->p_flags & P_PPWAIT) { 1407 sigsetfrompid(curthread, p, sig); 1408 SIGADDSET_ATOMIC(p->p_siglist, sig); 1409 lwkt_reltoken(&p->p_token); 1410 goto out; 1411 } 1412 1413 /* 1414 * Do not actually try to manipulate the process, but simply 1415 * stop it. Lwps will stop as soon as they safely can. 1416 * 1417 * Ignore stop if the process is exiting. 1418 */ 1419 if ((p->p_flags & P_WEXIT) == 0) { 1420 p->p_xstat = sig; 1421 proc_stop(p, SSTOP); 1422 } 1423 lwkt_reltoken(&p->p_token); 1424 goto out; 1425 } 1426 1427 /* 1428 * If it is a CONT signal with default action, just ignore it. 1429 */ 1430 if ((prop & SA_CONT) && action == SIG_DFL) 1431 goto out; 1432 1433 /* 1434 * Mark signal pending at this specific thread. 1435 */ 1436 sigsetfrompid(curthread, p, sig); 1437 spin_lock(&lp->lwp_spin); 1438 SIGADDSET(lp->lwp_siglist, sig); 1439 spin_unlock(&lp->lwp_spin); 1440 1441 lwp_signotify(lp); 1442 1443 out: 1444 if (lp) { 1445 lwkt_reltoken(&lp->lwp_token); 1446 LWPRELE(lp); 1447 } else { 1448 lwkt_reltoken(&p->p_token); 1449 } 1450 PRELE(p); 1451 } 1452 1453 /* 1454 * Notify the LWP that a signal has arrived. The LWP does not have to be 1455 * sleeping on the current cpu. 1456 * 1457 * p->p_token and lp->lwp_token must be held on call. 1458 * 1459 * We can only safely schedule the thread on its current cpu and only if 1460 * one of the SINTR flags is set. If an SINTR flag is set AND we are on 1461 * the correct cpu we are properly interlocked, otherwise we could be 1462 * racing other thread transition states (or the lwp is on the user scheduler 1463 * runq but not scheduled) and must not do anything. 1464 * 1465 * Since we hold the lwp token we know the lwp cannot be ripped out from 1466 * under us so we can safely hold it to prevent it from being ripped out 1467 * from under us if we are forced to IPI another cpu to make the local 1468 * checks there. 1469 * 1470 * Adjustment of lp->lwp_stat can only occur when we hold the lwp_token, 1471 * which we won't in an IPI so any fixups have to be done here, effectively 1472 * replicating part of what setrunnable() does. 1473 */ 1474 static void 1475 lwp_signotify(struct lwp *lp) 1476 { 1477 thread_t dtd; 1478 1479 ASSERT_LWKT_TOKEN_HELD(&lp->lwp_token); 1480 dtd = lp->lwp_thread; 1481 1482 crit_enter(); 1483 if (lp == lwkt_preempted_proc()) { 1484 /* 1485 * lwp is on the current cpu AND it is currently running 1486 * (we preempted it). 1487 */ 1488 signotify(); 1489 } else if (lp->lwp_flags & LWP_SINTR) { 1490 /* 1491 * lwp is sitting in tsleep() with PCATCH set 1492 */ 1493 if (dtd->td_gd == mycpu) { 1494 setrunnable(lp); 1495 } else { 1496 /* 1497 * We can only adjust lwp_stat while we hold the 1498 * lwp_token, and we won't in the IPI function. 1499 */ 1500 LWPHOLD(lp); 1501 if (lp->lwp_stat == LSSTOP) 1502 lp->lwp_stat = LSSLEEP; 1503 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp); 1504 } 1505 } else if (dtd->td_flags & TDF_SINTR) { 1506 /* 1507 * lwp is sitting in lwkt_sleep() with PCATCH set. 1508 */ 1509 if (dtd->td_gd == mycpu) { 1510 setrunnable(lp); 1511 } else { 1512 /* 1513 * We can only adjust lwp_stat while we hold the 1514 * lwp_token, and we won't in the IPI function. 1515 */ 1516 LWPHOLD(lp); 1517 if (lp->lwp_stat == LSSTOP) 1518 lp->lwp_stat = LSSLEEP; 1519 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp); 1520 } 1521 } else { 1522 /* 1523 * Otherwise the lwp is either in some uninterruptible state 1524 * or it is on the userland scheduler's runqueue waiting to 1525 * be scheduled to a cpu, or it is running in userland. We 1526 * generally want to send an IPI so a running target gets the 1527 * signal ASAP, otherwise a scheduler-tick worth of latency 1528 * will occur. 1529 * 1530 * Issue an IPI to the remote cpu to knock it into the kernel, 1531 * remote cpu will issue the cpu-local signotify() if the IPI 1532 * preempts the desired thread. 1533 */ 1534 if (dtd->td_gd != mycpu) { 1535 LWPHOLD(lp); 1536 lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp); 1537 } 1538 } 1539 crit_exit(); 1540 } 1541 1542 /* 1543 * This function is called via an IPI so we cannot call setrunnable() here 1544 * (because while we hold the lp we don't own its token, and can't get it 1545 * from an IPI). 1546 * 1547 * We are interlocked by virtue of being on the same cpu as the target. If 1548 * we still are and LWP_SINTR or TDF_SINTR is set we can safely schedule 1549 * the target thread. 1550 */ 1551 static void 1552 lwp_signotify_remote(void *arg) 1553 { 1554 struct lwp *lp = arg; 1555 thread_t td = lp->lwp_thread; 1556 1557 if (lp == lwkt_preempted_proc()) { 1558 signotify(); 1559 LWPRELE(lp); 1560 } else if (td->td_gd == mycpu) { 1561 if ((lp->lwp_flags & LWP_SINTR) || 1562 (td->td_flags & TDF_SINTR)) { 1563 lwkt_schedule(td); 1564 } 1565 LWPRELE(lp); 1566 } else { 1567 lwkt_send_ipiq(td->td_gd, lwp_signotify_remote, lp); 1568 /* LWPHOLD() is forwarded to the target cpu */ 1569 } 1570 } 1571 1572 /* 1573 * Caller must hold p->p_token 1574 */ 1575 void 1576 proc_stop(struct proc *p, int stat) 1577 { 1578 struct proc *q; 1579 struct lwp *lp; 1580 1581 ASSERT_LWKT_TOKEN_HELD(&p->p_token); 1582 1583 /* 1584 * If somebody raced us, be happy with it. SCORE overrides SSTOP. 1585 */ 1586 if (stat == SCORE) { 1587 if (p->p_stat == SCORE || p->p_stat == SZOMB) 1588 return; 1589 } else { 1590 if (p->p_stat == SSTOP || p->p_stat == SCORE || 1591 p->p_stat == SZOMB) { 1592 return; 1593 } 1594 } 1595 p->p_stat = stat; 1596 1597 FOREACH_LWP_IN_PROC(lp, p) { 1598 LWPHOLD(lp); 1599 lwkt_gettoken(&lp->lwp_token); 1600 1601 switch (lp->lwp_stat) { 1602 case LSSTOP: 1603 /* 1604 * Do nothing, we are already counted in 1605 * p_nstopped. 1606 */ 1607 break; 1608 1609 case LSSLEEP: 1610 /* 1611 * We're sleeping, but we will stop before 1612 * returning to userspace, so count us 1613 * as stopped as well. We set LWP_MP_WSTOP 1614 * to signal the lwp that it should not 1615 * increase p_nstopped when reaching tstop(). 1616 * 1617 * LWP_MP_WSTOP is protected by lp->lwp_token. 1618 */ 1619 if ((lp->lwp_mpflags & LWP_MP_WSTOP) == 0) { 1620 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WSTOP); 1621 ++p->p_nstopped; 1622 } 1623 break; 1624 1625 case LSRUN: 1626 /* 1627 * We might notify ourself, but that's not 1628 * a problem. 1629 */ 1630 lwp_signotify(lp); 1631 break; 1632 } 1633 lwkt_reltoken(&lp->lwp_token); 1634 LWPRELE(lp); 1635 } 1636 1637 if (p->p_nstopped == p->p_nthreads) { 1638 /* 1639 * Token required to interlock kern_wait(). Reparenting can 1640 * also cause a race so we have to hold (q). 1641 */ 1642 q = p->p_pptr; 1643 PHOLD(q); 1644 lwkt_gettoken(&q->p_token); 1645 p->p_flags &= ~P_WAITED; 1646 wakeup(q); 1647 if ((q->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0) 1648 ksignal(p->p_pptr, SIGCHLD); 1649 lwkt_reltoken(&q->p_token); 1650 PRELE(q); 1651 } 1652 } 1653 1654 /* 1655 * Caller must hold p_token 1656 */ 1657 void 1658 proc_unstop(struct proc *p, int stat) 1659 { 1660 struct lwp *lp; 1661 1662 ASSERT_LWKT_TOKEN_HELD(&p->p_token); 1663 1664 if (p->p_stat != stat) 1665 return; 1666 1667 p->p_stat = SACTIVE; 1668 1669 FOREACH_LWP_IN_PROC(lp, p) { 1670 LWPHOLD(lp); 1671 lwkt_gettoken(&lp->lwp_token); 1672 1673 switch (lp->lwp_stat) { 1674 case LSRUN: 1675 /* 1676 * Uh? Not stopped? Well, I guess that's okay. 1677 */ 1678 if (bootverbose) 1679 kprintf("proc_unstop: lwp %d/%d not sleeping\n", 1680 p->p_pid, lp->lwp_tid); 1681 break; 1682 1683 case LSSLEEP: 1684 /* 1685 * Still sleeping. Don't bother waking it up. 1686 * However, if this thread was counted as 1687 * stopped, undo this. 1688 * 1689 * Nevertheless we call setrunnable() so that it 1690 * will wake up in case a signal or timeout arrived 1691 * in the meantime. 1692 * 1693 * LWP_MP_WSTOP is protected by lp->lwp_token. 1694 */ 1695 if (lp->lwp_mpflags & LWP_MP_WSTOP) { 1696 atomic_clear_int(&lp->lwp_mpflags, 1697 LWP_MP_WSTOP); 1698 --p->p_nstopped; 1699 } else { 1700 if (bootverbose) 1701 kprintf("proc_unstop: lwp %d/%d sleeping, not stopped\n", 1702 p->p_pid, lp->lwp_tid); 1703 } 1704 /* FALLTHROUGH */ 1705 1706 case LSSTOP: 1707 /* 1708 * This handles any lwp's waiting in a tsleep with 1709 * SIGCATCH. 1710 */ 1711 lwp_signotify(lp); 1712 break; 1713 1714 } 1715 lwkt_reltoken(&lp->lwp_token); 1716 LWPRELE(lp); 1717 } 1718 1719 /* 1720 * This handles any lwp's waiting in tstop(). We have interlocked 1721 * the setting of p_stat by acquiring and releasing each lpw's 1722 * token. 1723 */ 1724 wakeup(p); 1725 } 1726 1727 /* 1728 * Wait for all threads except the current thread to stop. 1729 */ 1730 static void 1731 proc_stopwait(struct proc *p) 1732 { 1733 while ((p->p_stat == SSTOP || p->p_stat == SCORE) && 1734 p->p_nstopped < p->p_nthreads - 1) { 1735 tsleep_interlock(&p->p_nstopped, 0); 1736 if (p->p_nstopped < p->p_nthreads - 1) { 1737 tsleep(&p->p_nstopped, PINTERLOCKED, "stopwt", hz); 1738 } 1739 } 1740 } 1741 1742 /* 1743 * No requirements. 1744 */ 1745 static int 1746 kern_sigtimedwait(sigset_t waitset, siginfo_t *info, struct timespec *timeout) 1747 { 1748 sigset_t savedmask, set; 1749 struct proc *p = curproc; 1750 struct lwp *lp = curthread->td_lwp; 1751 int error, sig, hz, timevalid = 0; 1752 struct timespec rts, ets, ts; 1753 struct timeval tv; 1754 1755 error = 0; 1756 sig = 0; 1757 ets.tv_sec = 0; /* silence compiler warning */ 1758 ets.tv_nsec = 0; /* silence compiler warning */ 1759 SIG_CANTMASK(waitset); 1760 savedmask = lp->lwp_sigmask; 1761 1762 if (timeout) { 1763 if (timeout->tv_sec >= 0 && timeout->tv_nsec >= 0 && 1764 timeout->tv_nsec < 1000000000) { 1765 timevalid = 1; 1766 getnanouptime(&rts); 1767 timespecadd(&rts, timeout, &ets); 1768 } 1769 } 1770 1771 for (;;) { 1772 set = lwp_sigpend(lp); 1773 SIGSETAND(set, waitset); 1774 if ((sig = sig_ffs(&set)) != 0) { 1775 SIGFILLSET(lp->lwp_sigmask); 1776 SIGDELSET(lp->lwp_sigmask, sig); 1777 SIG_CANTMASK(lp->lwp_sigmask); 1778 sig = issignal(lp, 1, 0); 1779 /* 1780 * It may be a STOP signal, in the case, issignal 1781 * returns 0, because we may stop there, and new 1782 * signal can come in, we should restart if we got 1783 * nothing. 1784 */ 1785 if (sig == 0) 1786 continue; 1787 else 1788 break; 1789 } 1790 1791 /* 1792 * Previous checking got nothing, and we retried but still 1793 * got nothing, we should return the error status. 1794 */ 1795 if (error) 1796 break; 1797 1798 /* 1799 * POSIX says this must be checked after looking for pending 1800 * signals. 1801 */ 1802 if (timeout) { 1803 if (timevalid == 0) { 1804 error = EINVAL; 1805 break; 1806 } 1807 getnanouptime(&rts); 1808 if (timespeccmp(&rts, &ets, >=)) { 1809 error = EAGAIN; 1810 break; 1811 } 1812 timespecsub(&ets, &rts, &ts); 1813 TIMESPEC_TO_TIMEVAL(&tv, &ts); 1814 hz = tvtohz_high(&tv); 1815 } else { 1816 hz = 0; 1817 } 1818 1819 lp->lwp_sigmask = savedmask; 1820 SIGSETNAND(lp->lwp_sigmask, waitset); 1821 /* 1822 * We won't ever be woken up. Instead, our sleep will 1823 * be broken in lwpsignal(). 1824 */ 1825 error = tsleep(&p->p_sigacts, PCATCH, "sigwt", hz); 1826 if (timeout) { 1827 if (error == ERESTART) { 1828 /* can not restart a timeout wait. */ 1829 error = EINTR; 1830 } else if (error == EAGAIN) { 1831 /* will calculate timeout by ourself. */ 1832 error = 0; 1833 } 1834 } 1835 /* Retry ... */ 1836 } 1837 1838 lp->lwp_sigmask = savedmask; 1839 if (sig) { 1840 error = 0; 1841 bzero(info, sizeof(*info)); 1842 info->si_signo = sig; 1843 spin_lock(&lp->lwp_spin); 1844 lwp_delsig(lp, sig, 1); /* take the signal! */ 1845 spin_unlock(&lp->lwp_spin); 1846 1847 if (sig == SIGKILL) { 1848 sigexit(lp, sig); 1849 /* NOT REACHED */ 1850 } 1851 } 1852 1853 return (error); 1854 } 1855 1856 /* 1857 * MPALMOSTSAFE 1858 */ 1859 int 1860 sys_sigtimedwait(struct sysmsg *sysmsg, const struct sigtimedwait_args *uap) 1861 { 1862 struct timespec ts; 1863 struct timespec *timeout; 1864 sigset_t set; 1865 siginfo_t info; 1866 int error; 1867 1868 if (uap->timeout) { 1869 error = copyin(uap->timeout, &ts, sizeof(ts)); 1870 if (error) 1871 return (error); 1872 timeout = &ts; 1873 } else { 1874 timeout = NULL; 1875 } 1876 error = copyin(uap->set, &set, sizeof(set)); 1877 if (error) 1878 return (error); 1879 error = kern_sigtimedwait(set, &info, timeout); 1880 if (error) 1881 return (error); 1882 if (uap->info) 1883 error = copyout(&info, uap->info, sizeof(info)); 1884 /* Repost if we got an error. */ 1885 /* 1886 * XXX lwp 1887 * 1888 * This could transform a thread-specific signal to another 1889 * thread / process pending signal. 1890 */ 1891 if (error) { 1892 ksignal(curproc, info.si_signo); 1893 } else { 1894 sysmsg->sysmsg_result = info.si_signo; 1895 } 1896 return (error); 1897 } 1898 1899 /* 1900 * MPALMOSTSAFE 1901 */ 1902 int 1903 sys_sigwaitinfo(struct sysmsg *sysmsg, const struct sigwaitinfo_args *uap) 1904 { 1905 siginfo_t info; 1906 sigset_t set; 1907 int error; 1908 1909 error = copyin(uap->set, &set, sizeof(set)); 1910 if (error) 1911 return (error); 1912 error = kern_sigtimedwait(set, &info, NULL); 1913 if (error) 1914 return (error); 1915 if (uap->info) 1916 error = copyout(&info, uap->info, sizeof(info)); 1917 /* Repost if we got an error. */ 1918 /* 1919 * XXX lwp 1920 * 1921 * This could transform a thread-specific signal to another 1922 * thread / process pending signal. 1923 */ 1924 if (error) { 1925 ksignal(curproc, info.si_signo); 1926 } else { 1927 sysmsg->sysmsg_result = info.si_signo; 1928 } 1929 return (error); 1930 } 1931 1932 /* 1933 * If the current process has received a signal that would interrupt a 1934 * system call, return EINTR or ERESTART as appropriate. 1935 */ 1936 int 1937 iscaught(struct lwp *lp) 1938 { 1939 struct proc *p = lp->lwp_proc; 1940 int sig; 1941 1942 if (p) { 1943 if ((sig = CURSIG(lp)) != 0) { 1944 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 1945 return (EINTR); 1946 return (ERESTART); 1947 } 1948 } 1949 return(EWOULDBLOCK); 1950 } 1951 1952 /* 1953 * If the current lwp/proc has received a signal (should be caught or cause 1954 * termination, should interrupt current syscall), return the signal number. 1955 * Stop signals with default action are processed immediately, then cleared; 1956 * they aren't returned. This is checked after each entry to the system for 1957 * a syscall or trap (though this can usually be done without calling issignal 1958 * by checking the pending signal masks in the CURSIG macro). 1959 * 1960 * This routine is called via CURSIG/__cursig. We will acquire and release 1961 * p->p_token but if the caller needs to interlock the test the caller must 1962 * also hold p->p_token. 1963 * 1964 * while (sig = CURSIG(curproc)) 1965 * postsig(sig); 1966 */ 1967 int 1968 issignal(struct lwp *lp, int maytrace, int *ptokp) 1969 { 1970 struct proc *p = lp->lwp_proc; 1971 sigset_t mask; 1972 int sig, prop; 1973 int haveptok; 1974 1975 for (;;) { 1976 int traced = (p->p_flags & P_TRACED) || (p->p_stops & S_SIG); 1977 1978 haveptok = 0; 1979 1980 /* 1981 * NOTE: Do not tstop here. Issue the proc_stop() 1982 * so other parties see that we know we need 1983 * to stop, but don't block here. Locks might 1984 * be held. 1985 * 1986 * XXX If this process is supposed to stop, stop this thread. 1987 * removed. 1988 */ 1989 #if 0 1990 if (STOPLWP(p, lp)) { 1991 lwkt_gettoken(&p->p_token); 1992 tstop(); 1993 lwkt_reltoken(&p->p_token); 1994 } 1995 #endif 1996 1997 /* 1998 * Quick check without token 1999 */ 2000 mask = lwp_sigpend(lp); 2001 SIGSETNAND(mask, lp->lwp_sigmask); 2002 if (p->p_flags & P_PPWAIT) 2003 SIG_STOPSIGMASK(mask); 2004 SIG_CONDBLOCKALLSIGS(mask, lp); 2005 2006 if (SIGISEMPTY(mask)) /* no signal to send */ 2007 return (0); 2008 2009 /* 2010 * If the signal is a member of the process signal set 2011 * we need p_token (even if it is also a member of the 2012 * lwp signal set). 2013 */ 2014 sig = sig_ffs(&mask); 2015 if (SIGISMEMBER(p->p_siglist, sig)) { 2016 /* 2017 * Recheck with token 2018 */ 2019 haveptok = 1; 2020 lwkt_gettoken(&p->p_token); 2021 2022 mask = lwp_sigpend(lp); 2023 SIGSETNAND(mask, lp->lwp_sigmask); 2024 if (p->p_flags & P_PPWAIT) 2025 SIG_STOPSIGMASK(mask); 2026 if (SIGISEMPTY(mask)) { /* no signal to send */ 2027 /* haveptok is TRUE */ 2028 lwkt_reltoken(&p->p_token); 2029 return (0); 2030 } 2031 sig = sig_ffs(&mask); 2032 } 2033 2034 STOPEVENT(p, S_SIG, sig); 2035 2036 /* 2037 * We should see pending but ignored signals 2038 * only if P_TRACED was on when they were posted. 2039 */ 2040 if (SIGISMEMBER(p->p_sigignore, sig) && (traced == 0)) { 2041 spin_lock(&lp->lwp_spin); 2042 lwp_delsig(lp, sig, haveptok); 2043 spin_unlock(&lp->lwp_spin); 2044 if (haveptok) 2045 lwkt_reltoken(&p->p_token); 2046 continue; 2047 } 2048 if (maytrace && 2049 (p->p_flags & P_TRACED) && 2050 (p->p_flags & P_PPWAIT) == 0) { 2051 /* 2052 * If traced, always stop, and stay stopped until 2053 * released by the parent. 2054 * 2055 * NOTE: SSTOP may get cleared during the loop, but 2056 * we do not re-notify the parent if we have 2057 * to loop several times waiting for the parent 2058 * to let us continue. XXX not sure if this is 2059 * still true 2060 * 2061 * NOTE: Do not tstop here. Issue the proc_stop() 2062 * so other parties see that we know we need 2063 * to stop, but don't block here. Locks might 2064 * be held. 2065 */ 2066 if (haveptok == 0) { 2067 lwkt_gettoken(&p->p_token); 2068 haveptok = 1; 2069 } 2070 p->p_xstat = sig; 2071 proc_stop(p, SSTOP); 2072 2073 /* 2074 * Normally we don't stop until we return to userland, but 2075 * make an exception when tracing and 'maytrace' is asserted. 2076 */ 2077 if (p->p_flags & P_TRACED) 2078 tstop(); 2079 2080 /* 2081 * If parent wants us to take the signal, 2082 * then it will leave it in p->p_xstat; 2083 * otherwise we just look for signals again. 2084 */ 2085 spin_lock(&lp->lwp_spin); 2086 lwp_delsig(lp, sig, 1); /* clear old signal */ 2087 spin_unlock(&lp->lwp_spin); 2088 sig = p->p_xstat; 2089 if (sig == 0) { 2090 /* haveptok is TRUE */ 2091 lwkt_reltoken(&p->p_token); 2092 continue; 2093 } 2094 2095 /* 2096 * Put the new signal into p_siglist. If the 2097 * signal is being masked, look for other signals. 2098 * 2099 * XXX lwp might need a call to ksignal() 2100 */ 2101 SIGADDSET_ATOMIC(p->p_siglist, sig); 2102 if (SIGISMEMBER(lp->lwp_sigmask, sig)) { 2103 /* haveptok is TRUE */ 2104 lwkt_reltoken(&p->p_token); 2105 continue; 2106 } 2107 2108 /* 2109 * If the traced bit got turned off, go back up 2110 * to the top to rescan signals. This ensures 2111 * that p_sig* and ps_sigact are consistent. 2112 */ 2113 if ((p->p_flags & P_TRACED) == 0) { 2114 /* haveptok is TRUE */ 2115 lwkt_reltoken(&p->p_token); 2116 continue; 2117 } 2118 } 2119 2120 /* 2121 * p_token may be held here 2122 */ 2123 prop = sigprop(sig); 2124 2125 /* 2126 * Decide whether the signal should be returned. 2127 * Return the signal's number, or fall through 2128 * to clear it from the pending mask. 2129 */ 2130 switch ((intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)]) { 2131 case (intptr_t)SIG_DFL: 2132 /* 2133 * Don't take default actions on system processes. 2134 */ 2135 if (p->p_pid <= 1) { 2136 #ifdef DIAGNOSTIC 2137 /* 2138 * Are you sure you want to ignore SIGSEGV 2139 * in init? XXX 2140 */ 2141 kprintf("Process (pid %lu) got signal %d\n", 2142 (u_long)p->p_pid, sig); 2143 #endif 2144 break; /* == ignore */ 2145 } 2146 2147 /* 2148 * Handle the in-kernel checkpoint action 2149 */ 2150 if (prop & SA_CKPT) { 2151 if (haveptok == 0) { 2152 lwkt_gettoken(&p->p_token); 2153 haveptok = 1; 2154 } 2155 checkpoint_signal_handler(lp); 2156 break; 2157 } 2158 2159 /* 2160 * If there is a pending stop signal to process 2161 * with default action, stop here, 2162 * then clear the signal. However, 2163 * if process is member of an orphaned 2164 * process group, ignore tty stop signals. 2165 */ 2166 if (prop & SA_STOP) { 2167 if (haveptok == 0) { 2168 lwkt_gettoken(&p->p_token); 2169 haveptok = 1; 2170 } 2171 if (p->p_flags & P_TRACED || 2172 (p->p_pgrp->pg_jobc == 0 && 2173 prop & SA_TTYSTOP)) 2174 break; /* == ignore */ 2175 if ((p->p_flags & P_WEXIT) == 0) { 2176 /* 2177 * NOTE: We do not block here. Issue 2178 * stopthe stop so other parties 2179 * see that we know we need to 2180 * stop. Locks might be held. 2181 */ 2182 p->p_xstat = sig; 2183 proc_stop(p, SSTOP); 2184 2185 #if 0 2186 tstop(); 2187 #endif 2188 } 2189 break; 2190 } else if (prop & SA_IGNORE) { 2191 /* 2192 * Except for SIGCONT, shouldn't get here. 2193 * Default action is to ignore; drop it. 2194 */ 2195 break; /* == ignore */ 2196 } else { 2197 if (ptokp) 2198 *ptokp = haveptok; 2199 else if (haveptok) 2200 lwkt_reltoken(&p->p_token); 2201 return (sig); 2202 } 2203 2204 /*NOTREACHED*/ 2205 2206 case (intptr_t)SIG_IGN: 2207 /* 2208 * Masking above should prevent us ever trying 2209 * to take action on an ignored signal other 2210 * than SIGCONT, unless process is traced. 2211 */ 2212 if ((prop & SA_CONT) == 0 && 2213 (p->p_flags & P_TRACED) == 0) 2214 kprintf("issignal\n"); 2215 break; /* == ignore */ 2216 2217 default: 2218 /* 2219 * This signal has an action, let 2220 * postsig() process it. 2221 */ 2222 if (ptokp) 2223 *ptokp = haveptok; 2224 else if (haveptok) 2225 lwkt_reltoken(&p->p_token); 2226 return (sig); 2227 } 2228 spin_lock(&lp->lwp_spin); 2229 lwp_delsig(lp, sig, haveptok); /* take the signal! */ 2230 spin_unlock(&lp->lwp_spin); 2231 2232 if (haveptok) 2233 lwkt_reltoken(&p->p_token); 2234 } 2235 /* NOTREACHED */ 2236 } 2237 2238 /* 2239 * Take the action for the specified signal from the current set of 2240 * pending signals. 2241 * 2242 * haveptok indicates whether the caller is holding p->p_token. If the 2243 * caller is, we are responsible for releasing it. 2244 * 2245 * This routine can only be called from the top-level trap from usermode. 2246 * It is expecting to be able to modify the top-level stack frame. 2247 */ 2248 void 2249 postsig(int sig, int haveptok) 2250 { 2251 struct lwp *lp = curthread->td_lwp; 2252 struct proc *p = lp->lwp_proc; 2253 struct sigacts *ps = p->p_sigacts; 2254 sig_t action; 2255 sigset_t returnmask; 2256 int code; 2257 2258 KASSERT(sig != 0, ("postsig")); 2259 2260 /* 2261 * If we are a virtual kernel running an emulated user process 2262 * context, switch back to the virtual kernel context before 2263 * trying to post the signal. 2264 */ 2265 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 2266 struct trapframe *tf = lp->lwp_md.md_regs; 2267 tf->tf_trapno = 0; 2268 vkernel_trap(lp, tf); 2269 } 2270 2271 KNOTE(&p->p_klist, NOTE_SIGNAL | sig); 2272 2273 spin_lock(&lp->lwp_spin); 2274 lwp_delsig(lp, sig, haveptok); 2275 spin_unlock(&lp->lwp_spin); 2276 action = ps->ps_sigact[_SIG_IDX(sig)]; 2277 #ifdef KTRACE 2278 if (KTRPOINT(lp->lwp_thread, KTR_PSIG)) 2279 ktrpsig(lp, sig, action, lp->lwp_flags & LWP_OLDMASK ? 2280 &lp->lwp_oldsigmask : &lp->lwp_sigmask, 0); 2281 #endif 2282 /* 2283 * We don't need p_token after this point. 2284 */ 2285 if (haveptok) 2286 lwkt_reltoken(&p->p_token); 2287 2288 STOPEVENT(p, S_SIG, sig); 2289 2290 if (action == SIG_DFL) { 2291 /* 2292 * Default action, where the default is to kill 2293 * the process. (Other cases were ignored above.) 2294 */ 2295 sigexit(lp, sig); 2296 /* NOTREACHED */ 2297 } else { 2298 /* 2299 * If we get here, the signal must be caught. 2300 */ 2301 KASSERT(action != SIG_IGN && !SIGISMEMBER(lp->lwp_sigmask, sig), 2302 ("postsig action")); 2303 2304 /* 2305 * Reset the signal handler if asked to 2306 */ 2307 if (SIGISMEMBER(ps->ps_sigreset, sig)) { 2308 /* 2309 * See kern_sigaction() for origin of this code. 2310 */ 2311 SIGDELSET(p->p_sigcatch, sig); 2312 if (sig != SIGCONT && 2313 sigprop(sig) & SA_IGNORE) 2314 SIGADDSET(p->p_sigignore, sig); 2315 ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL; 2316 } 2317 2318 /* 2319 * Set the signal mask and calculate the mask to restore 2320 * when the signal function returns. 2321 * 2322 * Special case: user has done a sigsuspend. Here the 2323 * current mask is not of interest, but rather the 2324 * mask from before the sigsuspend is what we want 2325 * restored after the signal processing is completed. 2326 */ 2327 if (lp->lwp_flags & LWP_OLDMASK) { 2328 returnmask = lp->lwp_oldsigmask; 2329 lp->lwp_flags &= ~LWP_OLDMASK; 2330 } else { 2331 returnmask = lp->lwp_sigmask; 2332 } 2333 2334 SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]); 2335 if (!SIGISMEMBER(ps->ps_signodefer, sig)) 2336 SIGADDSET(lp->lwp_sigmask, sig); 2337 2338 lp->lwp_ru.ru_nsignals++; 2339 if (lp->lwp_sig != sig) { 2340 code = 0; 2341 } else { 2342 code = lp->lwp_code; 2343 lp->lwp_code = 0; 2344 lp->lwp_sig = 0; 2345 } 2346 (*p->p_sysent->sv_sendsig)(action, sig, &returnmask, code); 2347 } 2348 } 2349 2350 /* 2351 * Kill the current process for stated reason. 2352 */ 2353 void 2354 killproc(struct proc *p, char *why) 2355 { 2356 log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n", 2357 p->p_pid, p->p_comm, 2358 p->p_ucred ? p->p_ucred->cr_uid : -1, why); 2359 ksignal(p, SIGKILL); 2360 } 2361 2362 /* 2363 * Force the current process to exit with the specified signal, dumping core 2364 * if appropriate. We bypass the normal tests for masked and caught signals, 2365 * allowing unrecoverable failures to terminate the process without changing 2366 * signal state. Mark the accounting record with the signal termination. 2367 * If dumping core, save the signal number for the debugger. Calls exit and 2368 * does not return. 2369 * 2370 * This routine does not return. 2371 */ 2372 void 2373 sigexit(struct lwp *lp, int sig) 2374 { 2375 struct proc *p = lp->lwp_proc; 2376 2377 lwkt_gettoken(&p->p_token); 2378 p->p_acflag |= AXSIG; 2379 if (sigprop(sig) & SA_CORE) { 2380 lp->lwp_sig = sig; 2381 2382 /* 2383 * All threads must be stopped before we can safely coredump. 2384 * Stop threads using SCORE, which cannot be overridden. 2385 */ 2386 if (p->p_stat != SCORE) { 2387 proc_stop(p, SCORE); 2388 proc_stopwait(p); 2389 2390 if (coredump(lp, sig) == 0) 2391 sig |= WCOREFLAG; 2392 p->p_stat = SSTOP; 2393 } 2394 2395 /* 2396 * Log signals which would cause core dumps 2397 * (Log as LOG_INFO to appease those who don't want 2398 * these messages.) 2399 * XXX : Todo, as well as euid, write out ruid too 2400 */ 2401 if (kern_logsigexit) { 2402 log(LOG_INFO, 2403 "pid %d (%s), uid %d: exited on signal %d%s\n", 2404 p->p_pid, p->p_comm, 2405 p->p_ucred ? p->p_ucred->cr_uid : -1, 2406 sig &~ WCOREFLAG, 2407 sig & WCOREFLAG ? " (core dumped)" : ""); 2408 if (kern_logsigexit > 1) 2409 kprintf("DEBUG - waiting on kern.logsigexit\n"); 2410 while (kern_logsigexit > 1) { 2411 tsleep(&kern_logsigexit, 0, "DEBUG", hz); 2412 } 2413 } 2414 } 2415 lwkt_reltoken(&p->p_token); 2416 exit1(W_EXITCODE(0, sig)); 2417 /* NOTREACHED */ 2418 } 2419 2420 static char corefilename[MAXPATHLEN+1] = {"%N.core"}; 2421 SYSCTL_STRING(_kern, OID_AUTO, corefile, CTLFLAG_RW, corefilename, 2422 sizeof(corefilename), "process corefile name format string"); 2423 2424 /* 2425 * expand_name(name, uid, pid) 2426 * Expand the name described in corefilename, using name, uid, and pid. 2427 * corefilename is a kprintf-like string, with three format specifiers: 2428 * %N name of process ("name") 2429 * %P process id (pid) 2430 * %U user id (uid) 2431 * For example, "%N.core" is the default; they can be disabled completely 2432 * by using "/dev/null", or all core files can be stored in "/cores/%U/%N-%P". 2433 * This is controlled by the sysctl variable kern.corefile (see above). 2434 */ 2435 2436 static char * 2437 expand_name(const char *name, uid_t uid, pid_t pid) 2438 { 2439 char *temp; 2440 char buf[11]; /* Buffer for pid/uid -- max 4B */ 2441 int i, n; 2442 char *format = corefilename; 2443 size_t namelen; 2444 2445 temp = kmalloc(MAXPATHLEN + 1, M_TEMP, M_NOWAIT); 2446 if (temp == NULL) 2447 return NULL; 2448 namelen = strlen(name); 2449 for (i = 0, n = 0; n < MAXPATHLEN && format[i]; i++) { 2450 int l; 2451 switch (format[i]) { 2452 case '%': /* Format character */ 2453 i++; 2454 switch (format[i]) { 2455 case '%': 2456 temp[n++] = '%'; 2457 break; 2458 case 'N': /* process name */ 2459 if ((n + namelen) > MAXPATHLEN) { 2460 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n", 2461 pid, name, uid, temp, name); 2462 kfree(temp, M_TEMP); 2463 return NULL; 2464 } 2465 memcpy(temp+n, name, namelen); 2466 n += namelen; 2467 break; 2468 case 'P': /* process id */ 2469 l = ksprintf(buf, "%u", pid); 2470 if ((n + l) > MAXPATHLEN) { 2471 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n", 2472 pid, name, uid, temp, name); 2473 kfree(temp, M_TEMP); 2474 return NULL; 2475 } 2476 memcpy(temp+n, buf, l); 2477 n += l; 2478 break; 2479 case 'U': /* user id */ 2480 l = ksprintf(buf, "%u", uid); 2481 if ((n + l) > MAXPATHLEN) { 2482 log(LOG_ERR, "pid %d (%s), uid (%u): Path `%s%s' is too long\n", 2483 pid, name, uid, temp, name); 2484 kfree(temp, M_TEMP); 2485 return NULL; 2486 } 2487 memcpy(temp+n, buf, l); 2488 n += l; 2489 break; 2490 default: 2491 log(LOG_ERR, "Unknown format character %c in `%s'\n", format[i], format); 2492 } 2493 break; 2494 default: 2495 temp[n++] = format[i]; 2496 } 2497 } 2498 temp[n] = '\0'; 2499 return temp; 2500 } 2501 2502 /* 2503 * Dump a process' core. The main routine does some 2504 * policy checking, and creates the name of the coredump; 2505 * then it passes on a vnode and a size limit to the process-specific 2506 * coredump routine if there is one; if there _is not_ one, it returns 2507 * ENOSYS; otherwise it returns the error from the process-specific routine. 2508 * 2509 * The parameter `lp' is the lwp which triggered the coredump. 2510 */ 2511 2512 static int 2513 coredump(struct lwp *lp, int sig) 2514 { 2515 struct proc *p = lp->lwp_proc; 2516 struct vnode *vp; 2517 struct ucred *cred = p->p_ucred; 2518 struct flock lf; 2519 struct nlookupdata nd; 2520 struct vattr vattr; 2521 int error, error1; 2522 char *name; /* name of corefile */ 2523 off_t limit; 2524 2525 STOPEVENT(p, S_CORE, 0); 2526 2527 if (((sugid_coredump == 0) && (p->p_flags & P_SUGID)) || 2528 do_coredump == 0) 2529 { 2530 return (EFAULT); 2531 } 2532 2533 /* 2534 * Note that the bulk of limit checking is done after 2535 * the corefile is created. The exception is if the limit 2536 * for corefiles is 0, in which case we don't bother 2537 * creating the corefile at all. This layout means that 2538 * a corefile is truncated instead of not being created, 2539 * if it is larger than the limit. 2540 */ 2541 limit = p->p_rlimit[RLIMIT_CORE].rlim_cur; 2542 if (limit == 0) 2543 return EFBIG; 2544 2545 name = expand_name(p->p_comm, p->p_ucred->cr_uid, p->p_pid); 2546 if (name == NULL) 2547 return (EINVAL); 2548 error = nlookup_init(&nd, name, UIO_SYSSPACE, NLC_LOCKVP); 2549 if (error == 0) 2550 error = vn_open(&nd, NULL, 2551 O_CREAT | FWRITE | O_NOFOLLOW, 2552 S_IRUSR | S_IWUSR); 2553 kfree(name, M_TEMP); 2554 if (error) { 2555 nlookup_done(&nd); 2556 return (error); 2557 } 2558 vp = nd.nl_open_vp; 2559 nd.nl_open_vp = NULL; 2560 nlookup_done(&nd); 2561 2562 vn_unlock(vp); 2563 lf.l_whence = SEEK_SET; 2564 lf.l_start = 0; 2565 lf.l_len = 0; 2566 lf.l_type = F_WRLCK; 2567 error = VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &lf, 0); 2568 if (error) 2569 goto out2; 2570 2571 /* Don't dump to non-regular files or files with links. */ 2572 if (vp->v_type != VREG || 2573 VOP_GETATTR(vp, &vattr) || vattr.va_nlink != 1) { 2574 error = EFAULT; 2575 goto out1; 2576 } 2577 2578 /* Don't dump to files current user does not own */ 2579 if (vattr.va_uid != p->p_ucred->cr_uid) { 2580 error = EFAULT; 2581 goto out1; 2582 } 2583 2584 VATTR_NULL(&vattr); 2585 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2586 vattr.va_size = 0; 2587 VOP_SETATTR(vp, &vattr, cred); 2588 p->p_acflag |= ACORE; 2589 vn_unlock(vp); 2590 2591 error = p->p_sysent->sv_coredump ? 2592 p->p_sysent->sv_coredump(lp, sig, vp, limit) : ENOSYS; 2593 2594 out1: 2595 lf.l_type = F_UNLCK; 2596 VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &lf, 0); 2597 out2: 2598 error1 = vn_close(vp, FWRITE, NULL); 2599 if (error == 0) 2600 error = error1; 2601 return (error); 2602 } 2603 2604 /* 2605 * Nonexistent system call-- signal process (may want to handle it). 2606 * Flag error in case process won't see signal immediately (blocked or ignored). 2607 * 2608 * MPALMOSTSAFE 2609 */ 2610 /* ARGSUSED */ 2611 int 2612 sys_nosys(struct sysmsg *sysmsg, const struct nosys_args *args) 2613 { 2614 lwpsignal(curproc, curthread->td_lwp, SIGSYS); 2615 return (EINVAL); 2616 } 2617 2618 /* 2619 * Send a SIGIO or SIGURG signal to a process or process group using 2620 * stored credentials rather than those of the current process. 2621 */ 2622 void 2623 pgsigio(struct sigio *sigio, int sig, int checkctty) 2624 { 2625 if (sigio == NULL) 2626 return; 2627 2628 if (sigio->sio_pgid > 0) { 2629 if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, 2630 sigio->sio_proc)) 2631 ksignal(sigio->sio_proc, sig); 2632 } else if (sigio->sio_pgid < 0) { 2633 struct proc *p; 2634 struct pgrp *pg = sigio->sio_pgrp; 2635 2636 /* 2637 * Must interlock all signals against fork 2638 */ 2639 pgref(pg); 2640 lockmgr(&pg->pg_lock, LK_EXCLUSIVE); 2641 LIST_FOREACH(p, &pg->pg_members, p_pglist) { 2642 if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, p) && 2643 (checkctty == 0 || (p->p_flags & P_CONTROLT))) 2644 ksignal(p, sig); 2645 } 2646 lockmgr(&pg->pg_lock, LK_RELEASE); 2647 pgrel(pg); 2648 } 2649 } 2650 2651 static int 2652 filt_sigattach(struct knote *kn) 2653 { 2654 struct proc *p = curproc; 2655 2656 kn->kn_ptr.p_proc = p; 2657 kn->kn_flags |= EV_CLEAR; /* automatically set */ 2658 2659 /* XXX lock the proc here while adding to the list? */ 2660 knote_insert(&p->p_klist, kn); 2661 2662 return (0); 2663 } 2664 2665 static void 2666 filt_sigdetach(struct knote *kn) 2667 { 2668 struct proc *p = kn->kn_ptr.p_proc; 2669 2670 knote_remove(&p->p_klist, kn); 2671 } 2672 2673 /* 2674 * signal knotes are shared with proc knotes, so we apply a mask to 2675 * the hint in order to differentiate them from process hints. This 2676 * could be avoided by using a signal-specific knote list, but probably 2677 * isn't worth the trouble. 2678 */ 2679 static int 2680 filt_signal(struct knote *kn, long hint) 2681 { 2682 if (hint & NOTE_SIGNAL) { 2683 hint &= ~NOTE_SIGNAL; 2684 2685 if (kn->kn_id == hint) 2686 kn->kn_data++; 2687 } 2688 return (kn->kn_data != 0); 2689 } 2690