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 * 4. 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_fork.c 8.6 (Berkeley) 4/8/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 #include "opt_mac.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/sysproto.h> 46 #include <sys/eventhandler.h> 47 #include <sys/filedesc.h> 48 #include <sys/kernel.h> 49 #include <sys/kthread.h> 50 #include <sys/sysctl.h> 51 #include <sys/lock.h> 52 #include <sys/malloc.h> 53 #include <sys/mutex.h> 54 #include <sys/priv.h> 55 #include <sys/proc.h> 56 #include <sys/pioctl.h> 57 #include <sys/resourcevar.h> 58 #include <sys/sched.h> 59 #include <sys/syscall.h> 60 #include <sys/vmmeter.h> 61 #include <sys/vnode.h> 62 #include <sys/acct.h> 63 #include <sys/ktr.h> 64 #include <sys/ktrace.h> 65 #include <sys/unistd.h> 66 #include <sys/sx.h> 67 #include <sys/signalvar.h> 68 69 #include <security/audit/audit.h> 70 #include <security/mac/mac_framework.h> 71 72 #include <vm/vm.h> 73 #include <vm/pmap.h> 74 #include <vm/vm_map.h> 75 #include <vm/vm_extern.h> 76 #include <vm/uma.h> 77 78 79 #ifndef _SYS_SYSPROTO_H_ 80 struct fork_args { 81 int dummy; 82 }; 83 #endif 84 85 static int forksleep; /* Place for fork1() to sleep on. */ 86 87 /* 88 * MPSAFE 89 */ 90 /* ARGSUSED */ 91 int 92 fork(td, uap) 93 struct thread *td; 94 struct fork_args *uap; 95 { 96 int error; 97 struct proc *p2; 98 99 error = fork1(td, RFFDG | RFPROC, 0, &p2); 100 if (error == 0) { 101 td->td_retval[0] = p2->p_pid; 102 td->td_retval[1] = 0; 103 } 104 return (error); 105 } 106 107 /* 108 * MPSAFE 109 */ 110 /* ARGSUSED */ 111 int 112 vfork(td, uap) 113 struct thread *td; 114 struct vfork_args *uap; 115 { 116 int error; 117 struct proc *p2; 118 119 error = fork1(td, RFFDG | RFPROC | RFPPWAIT | RFMEM, 0, &p2); 120 if (error == 0) { 121 td->td_retval[0] = p2->p_pid; 122 td->td_retval[1] = 0; 123 } 124 return (error); 125 } 126 127 /* 128 * MPSAFE 129 */ 130 int 131 rfork(td, uap) 132 struct thread *td; 133 struct rfork_args *uap; 134 { 135 struct proc *p2; 136 int error; 137 138 /* Don't allow kernel-only flags. */ 139 if ((uap->flags & RFKERNELONLY) != 0) 140 return (EINVAL); 141 142 AUDIT_ARG(fflags, uap->flags); 143 error = fork1(td, uap->flags, 0, &p2); 144 if (error == 0) { 145 td->td_retval[0] = p2 ? p2->p_pid : 0; 146 td->td_retval[1] = 0; 147 } 148 return (error); 149 } 150 151 int nprocs = 1; /* process 0 */ 152 int lastpid = 0; 153 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0, 154 "Last used PID"); 155 156 /* 157 * Random component to lastpid generation. We mix in a random factor to make 158 * it a little harder to predict. We sanity check the modulus value to avoid 159 * doing it in critical paths. Don't let it be too small or we pointlessly 160 * waste randomness entropy, and don't let it be impossibly large. Using a 161 * modulus that is too big causes a LOT more process table scans and slows 162 * down fork processing as the pidchecked caching is defeated. 163 */ 164 static int randompid = 0; 165 166 static int 167 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 168 { 169 int error, pid; 170 171 error = sysctl_wire_old_buffer(req, sizeof(int)); 172 if (error != 0) 173 return(error); 174 sx_xlock(&allproc_lock); 175 pid = randompid; 176 error = sysctl_handle_int(oidp, &pid, 0, req); 177 if (error == 0 && req->newptr != NULL) { 178 if (pid < 0 || pid > PID_MAX - 100) /* out of range */ 179 pid = PID_MAX - 100; 180 else if (pid < 2) /* NOP */ 181 pid = 0; 182 else if (pid < 100) /* Make it reasonable */ 183 pid = 100; 184 randompid = pid; 185 } 186 sx_xunlock(&allproc_lock); 187 return (error); 188 } 189 190 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 191 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 192 193 int 194 fork1(td, flags, pages, procp) 195 struct thread *td; 196 int flags; 197 int pages; 198 struct proc **procp; 199 { 200 struct proc *p1, *p2, *pptr; 201 struct proc *newproc; 202 int ok, trypid; 203 static int curfail, pidchecked = 0; 204 static struct timeval lastfail; 205 struct filedesc *fd; 206 struct filedesc_to_leader *fdtol; 207 struct thread *td2; 208 #ifdef KSE 209 struct ksegrp *kg2; 210 #endif 211 struct sigacts *newsigacts; 212 int error; 213 214 /* Can't copy and clear. */ 215 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 216 return (EINVAL); 217 218 p1 = td->td_proc; 219 220 /* 221 * Here we don't create a new process, but we divorce 222 * certain parts of a process from itself. 223 */ 224 if ((flags & RFPROC) == 0) { 225 if ((p1->p_flag & P_HADTHREADS) && 226 (flags & (RFCFDG | RFFDG))) { 227 PROC_LOCK(p1); 228 if (thread_single(SINGLE_BOUNDARY)) { 229 PROC_UNLOCK(p1); 230 return (ERESTART); 231 } 232 PROC_UNLOCK(p1); 233 } 234 235 vm_forkproc(td, NULL, NULL, flags); 236 237 /* 238 * Close all file descriptors. 239 */ 240 if (flags & RFCFDG) { 241 struct filedesc *fdtmp; 242 fdtmp = fdinit(td->td_proc->p_fd); 243 fdfree(td); 244 p1->p_fd = fdtmp; 245 } 246 247 /* 248 * Unshare file descriptors (from parent). 249 */ 250 if (flags & RFFDG) 251 fdunshare(p1, td); 252 253 if ((p1->p_flag & P_HADTHREADS) && 254 (flags & (RFCFDG | RFFDG))) { 255 PROC_LOCK(p1); 256 thread_single_end(); 257 PROC_UNLOCK(p1); 258 } 259 *procp = NULL; 260 return (0); 261 } 262 263 /* 264 * Note 1:1 allows for forking with one thread coming out on the 265 * other side with the expectation that the process is about to 266 * exec. 267 */ 268 if (p1->p_flag & P_HADTHREADS) { 269 /* 270 * Idle the other threads for a second. 271 * Since the user space is copied, it must remain stable. 272 * In addition, all threads (from the user perspective) 273 * need to either be suspended or in the kernel, 274 * where they will try restart in the parent and will 275 * be aborted in the child. 276 */ 277 PROC_LOCK(p1); 278 if (thread_single(SINGLE_NO_EXIT)) { 279 /* Abort. Someone else is single threading before us. */ 280 PROC_UNLOCK(p1); 281 return (ERESTART); 282 } 283 PROC_UNLOCK(p1); 284 /* 285 * All other activity in this process 286 * is now suspended at the user boundary, 287 * (or other safe places if we think of any). 288 */ 289 } 290 291 /* Allocate new proc. */ 292 newproc = uma_zalloc(proc_zone, M_WAITOK); 293 #ifdef MAC 294 mac_init_proc(newproc); 295 #endif 296 #ifdef AUDIT 297 audit_proc_alloc(newproc); 298 #endif 299 knlist_init(&newproc->p_klist, &newproc->p_mtx, NULL, NULL, NULL); 300 STAILQ_INIT(&newproc->p_ktr); 301 302 /* We have to lock the process tree while we look for a pid. */ 303 sx_slock(&proctree_lock); 304 305 /* 306 * Although process entries are dynamically created, we still keep 307 * a global limit on the maximum number we will create. Don't allow 308 * a nonprivileged user to use the last ten processes; don't let root 309 * exceed the limit. The variable nprocs is the current number of 310 * processes, maxproc is the limit. 311 */ 312 sx_xlock(&allproc_lock); 313 if ((nprocs >= maxproc - 10 && 314 priv_check_cred(td->td_ucred, PRIV_MAXPROC, SUSER_RUID) != 0) || 315 nprocs >= maxproc) { 316 error = EAGAIN; 317 goto fail; 318 } 319 320 /* 321 * Increment the count of procs running with this uid. Don't allow 322 * a nonprivileged user to exceed their current limit. 323 * 324 * XXXRW: Can we avoid privilege here if it's not needed? 325 */ 326 error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, SUSER_RUID | 327 SUSER_ALLOWJAIL); 328 if (error == 0) 329 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0); 330 else { 331 PROC_LOCK(p1); 332 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 333 lim_cur(p1, RLIMIT_NPROC)); 334 PROC_UNLOCK(p1); 335 } 336 if (!ok) { 337 error = EAGAIN; 338 goto fail; 339 } 340 341 /* 342 * Increment the nprocs resource before blocking can occur. There 343 * are hard-limits as to the number of processes that can run. 344 */ 345 nprocs++; 346 347 /* 348 * Find an unused process ID. We remember a range of unused IDs 349 * ready to use (from lastpid+1 through pidchecked-1). 350 * 351 * If RFHIGHPID is set (used during system boot), do not allocate 352 * low-numbered pids. 353 */ 354 trypid = lastpid + 1; 355 if (flags & RFHIGHPID) { 356 if (trypid < 10) 357 trypid = 10; 358 } else { 359 if (randompid) 360 trypid += arc4random() % randompid; 361 } 362 retry: 363 /* 364 * If the process ID prototype has wrapped around, 365 * restart somewhat above 0, as the low-numbered procs 366 * tend to include daemons that don't exit. 367 */ 368 if (trypid >= PID_MAX) { 369 trypid = trypid % PID_MAX; 370 if (trypid < 100) 371 trypid += 100; 372 pidchecked = 0; 373 } 374 if (trypid >= pidchecked) { 375 int doingzomb = 0; 376 377 pidchecked = PID_MAX; 378 /* 379 * Scan the active and zombie procs to check whether this pid 380 * is in use. Remember the lowest pid that's greater 381 * than trypid, so we can avoid checking for a while. 382 */ 383 p2 = LIST_FIRST(&allproc); 384 again: 385 for (; p2 != NULL; p2 = LIST_NEXT(p2, p_list)) { 386 while (p2->p_pid == trypid || 387 (p2->p_pgrp != NULL && 388 (p2->p_pgrp->pg_id == trypid || 389 (p2->p_session != NULL && 390 p2->p_session->s_sid == trypid)))) { 391 trypid++; 392 if (trypid >= pidchecked) 393 goto retry; 394 } 395 if (p2->p_pid > trypid && pidchecked > p2->p_pid) 396 pidchecked = p2->p_pid; 397 if (p2->p_pgrp != NULL) { 398 if (p2->p_pgrp->pg_id > trypid && 399 pidchecked > p2->p_pgrp->pg_id) 400 pidchecked = p2->p_pgrp->pg_id; 401 if (p2->p_session != NULL && 402 p2->p_session->s_sid > trypid && 403 pidchecked > p2->p_session->s_sid) 404 pidchecked = p2->p_session->s_sid; 405 } 406 } 407 if (!doingzomb) { 408 doingzomb = 1; 409 p2 = LIST_FIRST(&zombproc); 410 goto again; 411 } 412 } 413 sx_sunlock(&proctree_lock); 414 415 /* 416 * RFHIGHPID does not mess with the lastpid counter during boot. 417 */ 418 if (flags & RFHIGHPID) 419 pidchecked = 0; 420 else 421 lastpid = trypid; 422 423 p2 = newproc; 424 p2->p_state = PRS_NEW; /* protect against others */ 425 p2->p_pid = trypid; 426 AUDIT_ARG(pid, p2->p_pid); 427 LIST_INSERT_HEAD(&allproc, p2, p_list); 428 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 429 sx_xunlock(&allproc_lock); 430 431 /* 432 * Malloc things while we don't hold any locks. 433 */ 434 if (flags & RFSIGSHARE) 435 newsigacts = NULL; 436 else 437 newsigacts = sigacts_alloc(); 438 439 /* 440 * Copy filedesc. 441 */ 442 if (flags & RFCFDG) { 443 fd = fdinit(p1->p_fd); 444 fdtol = NULL; 445 } else if (flags & RFFDG) { 446 fd = fdcopy(p1->p_fd); 447 fdtol = NULL; 448 } else { 449 fd = fdshare(p1->p_fd); 450 if (p1->p_fdtol == NULL) 451 p1->p_fdtol = 452 filedesc_to_leader_alloc(NULL, 453 NULL, 454 p1->p_leader); 455 if ((flags & RFTHREAD) != 0) { 456 /* 457 * Shared file descriptor table and 458 * shared process leaders. 459 */ 460 fdtol = p1->p_fdtol; 461 FILEDESC_LOCK_FAST(p1->p_fd); 462 fdtol->fdl_refcount++; 463 FILEDESC_UNLOCK_FAST(p1->p_fd); 464 } else { 465 /* 466 * Shared file descriptor table, and 467 * different process leaders 468 */ 469 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, 470 p1->p_fd, 471 p2); 472 } 473 } 474 /* 475 * Make a proc table entry for the new process. 476 * Start by zeroing the section of proc that is zero-initialized, 477 * then copy the section that is copied directly from the parent. 478 */ 479 td2 = FIRST_THREAD_IN_PROC(p2); 480 #ifdef KSE 481 kg2 = FIRST_KSEGRP_IN_PROC(p2); 482 #endif 483 484 /* Allocate and switch to an alternate kstack if specified. */ 485 if (pages != 0) 486 vm_thread_new_altkstack(td2, pages); 487 488 PROC_LOCK(p2); 489 PROC_LOCK(p1); 490 491 bzero(&p2->p_startzero, 492 __rangeof(struct proc, p_startzero, p_endzero)); 493 bzero(&td2->td_startzero, 494 __rangeof(struct thread, td_startzero, td_endzero)); 495 #ifdef KSE 496 bzero(&kg2->kg_startzero, 497 __rangeof(struct ksegrp, kg_startzero, kg_endzero)); 498 #endif 499 500 bcopy(&p1->p_startcopy, &p2->p_startcopy, 501 __rangeof(struct proc, p_startcopy, p_endcopy)); 502 bcopy(&td->td_startcopy, &td2->td_startcopy, 503 __rangeof(struct thread, td_startcopy, td_endcopy)); 504 #ifdef KSE 505 bcopy(&td->td_ksegrp->kg_startcopy, &kg2->kg_startcopy, 506 __rangeof(struct ksegrp, kg_startcopy, kg_endcopy)); 507 #endif 508 509 td2->td_sigstk = td->td_sigstk; 510 td2->td_sigmask = td->td_sigmask; 511 512 /* 513 * Duplicate sub-structures as needed. 514 * Increase reference counts on shared objects. 515 */ 516 p2->p_flag = 0; 517 if (p1->p_flag & P_PROFIL) 518 startprofclock(p2); 519 mtx_lock_spin(&sched_lock); 520 p2->p_sflag = PS_INMEM; 521 /* 522 * Allow the scheduler to adjust the priority of the child and 523 * parent while we hold the sched_lock. 524 */ 525 sched_fork(td, td2); 526 527 mtx_unlock_spin(&sched_lock); 528 p2->p_ucred = crhold(td->td_ucred); 529 #ifdef KSE 530 td2->td_ucred = crhold(p2->p_ucred); /* XXXKSE */ 531 #else 532 td2->td_ucred = crhold(p2->p_ucred); 533 #endif 534 #ifdef AUDIT 535 audit_proc_fork(p1, p2); 536 #endif 537 pargs_hold(p2->p_args); 538 539 if (flags & RFSIGSHARE) { 540 p2->p_sigacts = sigacts_hold(p1->p_sigacts); 541 } else { 542 sigacts_copy(newsigacts, p1->p_sigacts); 543 p2->p_sigacts = newsigacts; 544 } 545 if (flags & RFLINUXTHPN) 546 p2->p_sigparent = SIGUSR1; 547 else 548 p2->p_sigparent = SIGCHLD; 549 550 p2->p_textvp = p1->p_textvp; 551 p2->p_fd = fd; 552 p2->p_fdtol = fdtol; 553 554 /* 555 * p_limit is copy-on-write. Bump its refcount. 556 */ 557 p2->p_limit = lim_hold(p1->p_limit); 558 559 pstats_fork(p1->p_stats, p2->p_stats); 560 561 PROC_UNLOCK(p1); 562 PROC_UNLOCK(p2); 563 564 /* Bump references to the text vnode (for procfs) */ 565 if (p2->p_textvp) 566 vref(p2->p_textvp); 567 568 /* 569 * Set up linkage for kernel based threading. 570 */ 571 if ((flags & RFTHREAD) != 0) { 572 mtx_lock(&ppeers_lock); 573 p2->p_peers = p1->p_peers; 574 p1->p_peers = p2; 575 p2->p_leader = p1->p_leader; 576 mtx_unlock(&ppeers_lock); 577 PROC_LOCK(p1->p_leader); 578 if ((p1->p_leader->p_flag & P_WEXIT) != 0) { 579 PROC_UNLOCK(p1->p_leader); 580 /* 581 * The task leader is exiting, so process p1 is 582 * going to be killed shortly. Since p1 obviously 583 * isn't dead yet, we know that the leader is either 584 * sending SIGKILL's to all the processes in this 585 * task or is sleeping waiting for all the peers to 586 * exit. We let p1 complete the fork, but we need 587 * to go ahead and kill the new process p2 since 588 * the task leader may not get a chance to send 589 * SIGKILL to it. We leave it on the list so that 590 * the task leader will wait for this new process 591 * to commit suicide. 592 */ 593 PROC_LOCK(p2); 594 psignal(p2, SIGKILL); 595 PROC_UNLOCK(p2); 596 } else 597 PROC_UNLOCK(p1->p_leader); 598 } else { 599 p2->p_peers = NULL; 600 p2->p_leader = p2; 601 } 602 603 sx_xlock(&proctree_lock); 604 PGRP_LOCK(p1->p_pgrp); 605 PROC_LOCK(p2); 606 PROC_LOCK(p1); 607 608 /* 609 * Preserve some more flags in subprocess. P_PROFIL has already 610 * been preserved. 611 */ 612 p2->p_flag |= p1->p_flag & P_SUGID; 613 td2->td_pflags |= td->td_pflags & TDP_ALTSTACK; 614 SESS_LOCK(p1->p_session); 615 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 616 p2->p_flag |= P_CONTROLT; 617 SESS_UNLOCK(p1->p_session); 618 if (flags & RFPPWAIT) 619 p2->p_flag |= P_PPWAIT; 620 621 p2->p_pgrp = p1->p_pgrp; 622 LIST_INSERT_AFTER(p1, p2, p_pglist); 623 PGRP_UNLOCK(p1->p_pgrp); 624 LIST_INIT(&p2->p_children); 625 626 callout_init(&p2->p_itcallout, CALLOUT_MPSAFE); 627 628 #ifdef KTRACE 629 /* 630 * Copy traceflag and tracefile if enabled. 631 */ 632 mtx_lock(&ktrace_mtx); 633 KASSERT(p2->p_tracevp == NULL, ("new process has a ktrace vnode")); 634 if (p1->p_traceflag & KTRFAC_INHERIT) { 635 p2->p_traceflag = p1->p_traceflag; 636 if ((p2->p_tracevp = p1->p_tracevp) != NULL) { 637 VREF(p2->p_tracevp); 638 KASSERT(p1->p_tracecred != NULL, 639 ("ktrace vnode with no cred")); 640 p2->p_tracecred = crhold(p1->p_tracecred); 641 } 642 } 643 mtx_unlock(&ktrace_mtx); 644 #endif 645 646 /* 647 * If PF_FORK is set, the child process inherits the 648 * procfs ioctl flags from its parent. 649 */ 650 if (p1->p_pfsflags & PF_FORK) { 651 p2->p_stops = p1->p_stops; 652 p2->p_pfsflags = p1->p_pfsflags; 653 } 654 655 /* 656 * This begins the section where we must prevent the parent 657 * from being swapped. 658 */ 659 _PHOLD(p1); 660 PROC_UNLOCK(p1); 661 662 /* 663 * Attach the new process to its parent. 664 * 665 * If RFNOWAIT is set, the newly created process becomes a child 666 * of init. This effectively disassociates the child from the 667 * parent. 668 */ 669 if (flags & RFNOWAIT) 670 pptr = initproc; 671 else 672 pptr = p1; 673 p2->p_pptr = pptr; 674 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 675 sx_xunlock(&proctree_lock); 676 677 /* Inform accounting that we have forked. */ 678 p2->p_acflag = AFORK; 679 PROC_UNLOCK(p2); 680 681 /* 682 * Finish creating the child process. It will return via a different 683 * execution path later. (ie: directly into user mode) 684 */ 685 vm_forkproc(td, p2, td2, flags); 686 687 if (flags == (RFFDG | RFPROC)) { 688 atomic_add_int(&cnt.v_forks, 1); 689 atomic_add_int(&cnt.v_forkpages, p2->p_vmspace->vm_dsize + 690 p2->p_vmspace->vm_ssize); 691 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 692 atomic_add_int(&cnt.v_vforks, 1); 693 atomic_add_int(&cnt.v_vforkpages, p2->p_vmspace->vm_dsize + 694 p2->p_vmspace->vm_ssize); 695 } else if (p1 == &proc0) { 696 atomic_add_int(&cnt.v_kthreads, 1); 697 atomic_add_int(&cnt.v_kthreadpages, p2->p_vmspace->vm_dsize + 698 p2->p_vmspace->vm_ssize); 699 } else { 700 atomic_add_int(&cnt.v_rforks, 1); 701 atomic_add_int(&cnt.v_rforkpages, p2->p_vmspace->vm_dsize + 702 p2->p_vmspace->vm_ssize); 703 } 704 705 /* 706 * Both processes are set up, now check if any loadable modules want 707 * to adjust anything. 708 * What if they have an error? XXX 709 */ 710 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags); 711 712 /* 713 * Set the child start time and mark the process as being complete. 714 */ 715 microuptime(&p2->p_stats->p_start); 716 mtx_lock_spin(&sched_lock); 717 p2->p_state = PRS_NORMAL; 718 719 /* 720 * If RFSTOPPED not requested, make child runnable and add to 721 * run queue. 722 */ 723 if ((flags & RFSTOPPED) == 0) { 724 TD_SET_CAN_RUN(td2); 725 setrunqueue(td2, SRQ_BORING); 726 } 727 mtx_unlock_spin(&sched_lock); 728 729 /* 730 * Now can be swapped. 731 */ 732 PROC_LOCK(p1); 733 _PRELE(p1); 734 735 /* 736 * Tell any interested parties about the new process. 737 */ 738 KNOTE_LOCKED(&p1->p_klist, NOTE_FORK | p2->p_pid); 739 740 PROC_UNLOCK(p1); 741 742 /* 743 * Preserve synchronization semantics of vfork. If waiting for 744 * child to exec or exit, set P_PPWAIT on child, and sleep on our 745 * proc (in case of exit). 746 */ 747 PROC_LOCK(p2); 748 while (p2->p_flag & P_PPWAIT) 749 msleep(p1, &p2->p_mtx, PWAIT, "ppwait", 0); 750 PROC_UNLOCK(p2); 751 752 /* 753 * If other threads are waiting, let them continue now. 754 */ 755 if (p1->p_flag & P_HADTHREADS) { 756 PROC_LOCK(p1); 757 thread_single_end(); 758 PROC_UNLOCK(p1); 759 } 760 761 /* 762 * Return child proc pointer to parent. 763 */ 764 *procp = p2; 765 return (0); 766 fail: 767 sx_sunlock(&proctree_lock); 768 if (ppsratecheck(&lastfail, &curfail, 1)) 769 printf("maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5).\n", 770 td->td_ucred->cr_ruid); 771 sx_xunlock(&allproc_lock); 772 #ifdef MAC 773 mac_destroy_proc(newproc); 774 #endif 775 #ifdef AUDIT 776 audit_proc_free(newproc); 777 #endif 778 uma_zfree(proc_zone, newproc); 779 if (p1->p_flag & P_HADTHREADS) { 780 PROC_LOCK(p1); 781 thread_single_end(); 782 PROC_UNLOCK(p1); 783 } 784 tsleep(&forksleep, PUSER, "fork", hz / 2); 785 return (error); 786 } 787 788 /* 789 * Handle the return of a child process from fork1(). This function 790 * is called from the MD fork_trampoline() entry point. 791 */ 792 void 793 fork_exit(callout, arg, frame) 794 void (*callout)(void *, struct trapframe *); 795 void *arg; 796 struct trapframe *frame; 797 { 798 struct proc *p; 799 struct thread *td; 800 801 /* 802 * Finish setting up thread glue so that it begins execution in a 803 * non-nested critical section with sched_lock held but not recursed. 804 */ 805 td = curthread; 806 p = td->td_proc; 807 td->td_oncpu = PCPU_GET(cpuid); 808 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new")); 809 810 sched_lock.mtx_lock = (uintptr_t)td; 811 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 812 CTR4(KTR_PROC, "fork_exit: new thread %p (kse %p, pid %d, %s)", 813 td, td->td_sched, p->p_pid, p->p_comm); 814 815 /* 816 * Processes normally resume in mi_switch() after being 817 * cpu_switch()'ed to, but when children start up they arrive here 818 * instead, so we must do much the same things as mi_switch() would. 819 */ 820 821 if ((td = PCPU_GET(deadthread))) { 822 PCPU_SET(deadthread, NULL); 823 thread_stash(td); 824 } 825 td = curthread; 826 mtx_unlock_spin(&sched_lock); 827 828 /* 829 * cpu_set_fork_handler intercepts this function call to 830 * have this call a non-return function to stay in kernel mode. 831 * initproc has its own fork handler, but it does return. 832 */ 833 KASSERT(callout != NULL, ("NULL callout in fork_exit")); 834 callout(arg, frame); 835 836 /* 837 * Check if a kernel thread misbehaved and returned from its main 838 * function. 839 */ 840 if (p->p_flag & P_KTHREAD) { 841 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 842 p->p_comm, p->p_pid); 843 kthread_exit(0); 844 } 845 mtx_assert(&Giant, MA_NOTOWNED); 846 847 EVENTHANDLER_INVOKE(schedtail, p); 848 } 849 850 /* 851 * Simplified back end of syscall(), used when returning from fork() 852 * directly into user mode. Giant is not held on entry, and must not 853 * be held on return. This function is passed in to fork_exit() as the 854 * first parameter and is called when returning to a new userland process. 855 */ 856 void 857 fork_return(td, frame) 858 struct thread *td; 859 struct trapframe *frame; 860 { 861 862 userret(td, frame); 863 #ifdef KTRACE 864 if (KTRPOINT(td, KTR_SYSRET)) 865 ktrsysret(SYS_fork, 0, 0); 866 #endif 867 mtx_assert(&Giant, MA_NOTOWNED); 868 } 869