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_kdtrace.h" 41 #include "opt_ktrace.h" 42 #include "opt_kstack_pages.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/sysproto.h> 47 #include <sys/eventhandler.h> 48 #include <sys/filedesc.h> 49 #include <sys/jail.h> 50 #include <sys/kernel.h> 51 #include <sys/kthread.h> 52 #include <sys/sysctl.h> 53 #include <sys/lock.h> 54 #include <sys/malloc.h> 55 #include <sys/mutex.h> 56 #include <sys/priv.h> 57 #include <sys/proc.h> 58 #include <sys/pioctl.h> 59 #include <sys/resourcevar.h> 60 #include <sys/sched.h> 61 #include <sys/syscall.h> 62 #include <sys/vmmeter.h> 63 #include <sys/vnode.h> 64 #include <sys/acct.h> 65 #include <sys/ktr.h> 66 #include <sys/ktrace.h> 67 #include <sys/unistd.h> 68 #include <sys/sdt.h> 69 #include <sys/sx.h> 70 #include <sys/signalvar.h> 71 72 #include <security/audit/audit.h> 73 #include <security/mac/mac_framework.h> 74 75 #include <vm/vm.h> 76 #include <vm/pmap.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_extern.h> 79 #include <vm/uma.h> 80 81 #ifdef KDTRACE_HOOKS 82 #include <sys/dtrace_bsd.h> 83 dtrace_fork_func_t dtrace_fasttrap_fork; 84 #endif 85 86 SDT_PROVIDER_DECLARE(proc); 87 SDT_PROBE_DEFINE(proc, kernel, , create, create); 88 SDT_PROBE_ARGTYPE(proc, kernel, , create, 0, "struct proc *"); 89 SDT_PROBE_ARGTYPE(proc, kernel, , create, 1, "struct proc *"); 90 SDT_PROBE_ARGTYPE(proc, kernel, , create, 2, "int"); 91 92 #ifndef _SYS_SYSPROTO_H_ 93 struct fork_args { 94 int dummy; 95 }; 96 #endif 97 98 /* ARGSUSED */ 99 int 100 fork(struct thread *td, struct fork_args *uap) 101 { 102 int error; 103 struct proc *p2; 104 105 error = fork1(td, RFFDG | RFPROC, 0, &p2); 106 if (error == 0) { 107 td->td_retval[0] = p2->p_pid; 108 td->td_retval[1] = 0; 109 } 110 return (error); 111 } 112 113 /* ARGSUSED */ 114 int 115 vfork(td, uap) 116 struct thread *td; 117 struct vfork_args *uap; 118 { 119 int error, flags; 120 struct proc *p2; 121 122 #ifdef XEN 123 flags = RFFDG | RFPROC; /* validate that this is still an issue */ 124 #else 125 flags = RFFDG | RFPROC | RFPPWAIT | RFMEM; 126 #endif 127 error = fork1(td, flags, 0, &p2); 128 if (error == 0) { 129 td->td_retval[0] = p2->p_pid; 130 td->td_retval[1] = 0; 131 } 132 return (error); 133 } 134 135 int 136 rfork(struct thread *td, struct rfork_args *uap) 137 { 138 struct proc *p2; 139 int error; 140 141 /* Don't allow kernel-only flags. */ 142 if ((uap->flags & RFKERNELONLY) != 0) 143 return (EINVAL); 144 145 AUDIT_ARG_FFLAGS(uap->flags); 146 error = fork1(td, uap->flags, 0, &p2); 147 if (error == 0) { 148 td->td_retval[0] = p2 ? p2->p_pid : 0; 149 td->td_retval[1] = 0; 150 } 151 return (error); 152 } 153 154 int nprocs = 1; /* process 0 */ 155 int lastpid = 0; 156 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0, 157 "Last used PID"); 158 159 /* 160 * Random component to lastpid generation. We mix in a random factor to make 161 * it a little harder to predict. We sanity check the modulus value to avoid 162 * doing it in critical paths. Don't let it be too small or we pointlessly 163 * waste randomness entropy, and don't let it be impossibly large. Using a 164 * modulus that is too big causes a LOT more process table scans and slows 165 * down fork processing as the pidchecked caching is defeated. 166 */ 167 static int randompid = 0; 168 169 static int 170 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 171 { 172 int error, pid; 173 174 error = sysctl_wire_old_buffer(req, sizeof(int)); 175 if (error != 0) 176 return(error); 177 sx_xlock(&allproc_lock); 178 pid = randompid; 179 error = sysctl_handle_int(oidp, &pid, 0, req); 180 if (error == 0 && req->newptr != NULL) { 181 if (pid < 0 || pid > PID_MAX - 100) /* out of range */ 182 pid = PID_MAX - 100; 183 else if (pid < 2) /* NOP */ 184 pid = 0; 185 else if (pid < 100) /* Make it reasonable */ 186 pid = 100; 187 randompid = pid; 188 } 189 sx_xunlock(&allproc_lock); 190 return (error); 191 } 192 193 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 194 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 195 196 static int 197 fork_norfproc(struct thread *td, int flags, struct proc **procp) 198 { 199 int error; 200 struct proc *p1; 201 202 KASSERT((flags & RFPROC) == 0, 203 ("fork_norfproc called with RFPROC set")); 204 p1 = td->td_proc; 205 *procp = NULL; 206 207 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 208 (flags & (RFCFDG | RFFDG))) { 209 PROC_LOCK(p1); 210 if (thread_single(SINGLE_BOUNDARY)) { 211 PROC_UNLOCK(p1); 212 return (ERESTART); 213 } 214 PROC_UNLOCK(p1); 215 } 216 217 error = vm_forkproc(td, NULL, NULL, NULL, flags); 218 if (error) 219 goto fail; 220 221 /* 222 * Close all file descriptors. 223 */ 224 if (flags & RFCFDG) { 225 struct filedesc *fdtmp; 226 fdtmp = fdinit(td->td_proc->p_fd); 227 fdfree(td); 228 p1->p_fd = fdtmp; 229 } 230 231 /* 232 * Unshare file descriptors (from parent). 233 */ 234 if (flags & RFFDG) 235 fdunshare(p1, td); 236 237 fail: 238 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 239 (flags & (RFCFDG | RFFDG))) { 240 PROC_LOCK(p1); 241 thread_single_end(); 242 PROC_UNLOCK(p1); 243 } 244 return (error); 245 } 246 247 int 248 fork1(struct thread *td, int flags, int pages, struct proc **procp) 249 { 250 struct proc *p1, *p2, *pptr; 251 struct proc *newproc; 252 int ok, trypid; 253 static int curfail, pidchecked = 0; 254 static struct timeval lastfail; 255 struct filedesc *fd; 256 struct filedesc_to_leader *fdtol; 257 struct thread *td2; 258 struct sigacts *newsigacts; 259 struct vmspace *vm2; 260 vm_ooffset_t mem_charged; 261 int error; 262 263 /* Can't copy and clear. */ 264 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 265 return (EINVAL); 266 267 p1 = td->td_proc; 268 269 /* 270 * Here we don't create a new process, but we divorce 271 * certain parts of a process from itself. 272 */ 273 if ((flags & RFPROC) == 0) 274 return (fork_norfproc(td, flags, procp)); 275 276 /* 277 * XXX 278 * We did have single-threading code here 279 * however it proved un-needed and caused problems 280 */ 281 282 mem_charged = 0; 283 vm2 = NULL; 284 if (pages == 0) 285 pages = KSTACK_PAGES; 286 /* Allocate new proc. */ 287 newproc = uma_zalloc(proc_zone, M_WAITOK); 288 td2 = FIRST_THREAD_IN_PROC(newproc); 289 if (td2 == NULL) { 290 td2 = thread_alloc(pages); 291 if (td2 == NULL) { 292 error = ENOMEM; 293 goto fail1; 294 } 295 proc_linkup(newproc, td2); 296 } else { 297 if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) { 298 if (td2->td_kstack != 0) 299 vm_thread_dispose(td2); 300 if (!thread_alloc_stack(td2, pages)) { 301 error = ENOMEM; 302 goto fail1; 303 } 304 } 305 } 306 307 if ((flags & RFMEM) == 0) { 308 vm2 = vmspace_fork(p1->p_vmspace, &mem_charged); 309 if (vm2 == NULL) { 310 error = ENOMEM; 311 goto fail1; 312 } 313 if (!swap_reserve(mem_charged)) { 314 /* 315 * The swap reservation failed. The accounting 316 * from the entries of the copied vm2 will be 317 * substracted in vmspace_free(), so force the 318 * reservation there. 319 */ 320 swap_reserve_force(mem_charged); 321 error = ENOMEM; 322 goto fail1; 323 } 324 } else 325 vm2 = NULL; 326 #ifdef MAC 327 mac_proc_init(newproc); 328 #endif 329 knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx); 330 STAILQ_INIT(&newproc->p_ktr); 331 332 /* We have to lock the process tree while we look for a pid. */ 333 sx_slock(&proctree_lock); 334 335 /* 336 * Although process entries are dynamically created, we still keep 337 * a global limit on the maximum number we will create. Don't allow 338 * a nonprivileged user to use the last ten processes; don't let root 339 * exceed the limit. The variable nprocs is the current number of 340 * processes, maxproc is the limit. 341 */ 342 sx_xlock(&allproc_lock); 343 if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred, 344 PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) { 345 error = EAGAIN; 346 goto fail; 347 } 348 349 /* 350 * Increment the count of procs running with this uid. Don't allow 351 * a nonprivileged user to exceed their current limit. 352 * 353 * XXXRW: Can we avoid privilege here if it's not needed? 354 */ 355 error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0); 356 if (error == 0) 357 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0); 358 else { 359 PROC_LOCK(p1); 360 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 361 lim_cur(p1, RLIMIT_NPROC)); 362 PROC_UNLOCK(p1); 363 } 364 if (!ok) { 365 error = EAGAIN; 366 goto fail; 367 } 368 369 /* 370 * Increment the nprocs resource before blocking can occur. There 371 * are hard-limits as to the number of processes that can run. 372 */ 373 nprocs++; 374 375 /* 376 * Find an unused process ID. We remember a range of unused IDs 377 * ready to use (from lastpid+1 through pidchecked-1). 378 * 379 * If RFHIGHPID is set (used during system boot), do not allocate 380 * low-numbered pids. 381 */ 382 trypid = lastpid + 1; 383 if (flags & RFHIGHPID) { 384 if (trypid < 10) 385 trypid = 10; 386 } else { 387 if (randompid) 388 trypid += arc4random() % randompid; 389 } 390 retry: 391 /* 392 * If the process ID prototype has wrapped around, 393 * restart somewhat above 0, as the low-numbered procs 394 * tend to include daemons that don't exit. 395 */ 396 if (trypid >= PID_MAX) { 397 trypid = trypid % PID_MAX; 398 if (trypid < 100) 399 trypid += 100; 400 pidchecked = 0; 401 } 402 if (trypid >= pidchecked) { 403 int doingzomb = 0; 404 405 pidchecked = PID_MAX; 406 /* 407 * Scan the active and zombie procs to check whether this pid 408 * is in use. Remember the lowest pid that's greater 409 * than trypid, so we can avoid checking for a while. 410 */ 411 p2 = LIST_FIRST(&allproc); 412 again: 413 for (; p2 != NULL; p2 = LIST_NEXT(p2, p_list)) { 414 while (p2->p_pid == trypid || 415 (p2->p_pgrp != NULL && 416 (p2->p_pgrp->pg_id == trypid || 417 (p2->p_session != NULL && 418 p2->p_session->s_sid == trypid)))) { 419 trypid++; 420 if (trypid >= pidchecked) 421 goto retry; 422 } 423 if (p2->p_pid > trypid && pidchecked > p2->p_pid) 424 pidchecked = p2->p_pid; 425 if (p2->p_pgrp != NULL) { 426 if (p2->p_pgrp->pg_id > trypid && 427 pidchecked > p2->p_pgrp->pg_id) 428 pidchecked = p2->p_pgrp->pg_id; 429 if (p2->p_session != NULL && 430 p2->p_session->s_sid > trypid && 431 pidchecked > p2->p_session->s_sid) 432 pidchecked = p2->p_session->s_sid; 433 } 434 } 435 if (!doingzomb) { 436 doingzomb = 1; 437 p2 = LIST_FIRST(&zombproc); 438 goto again; 439 } 440 } 441 sx_sunlock(&proctree_lock); 442 443 /* 444 * RFHIGHPID does not mess with the lastpid counter during boot. 445 */ 446 if (flags & RFHIGHPID) 447 pidchecked = 0; 448 else 449 lastpid = trypid; 450 451 p2 = newproc; 452 p2->p_state = PRS_NEW; /* protect against others */ 453 p2->p_pid = trypid; 454 /* 455 * Allow the scheduler to initialize the child. 456 */ 457 thread_lock(td); 458 sched_fork(td, td2); 459 thread_unlock(td); 460 AUDIT_ARG_PID(p2->p_pid); 461 LIST_INSERT_HEAD(&allproc, p2, p_list); 462 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 463 tidhash_add(td2); 464 PROC_LOCK(p2); 465 PROC_LOCK(p1); 466 467 sx_xunlock(&allproc_lock); 468 469 bcopy(&p1->p_startcopy, &p2->p_startcopy, 470 __rangeof(struct proc, p_startcopy, p_endcopy)); 471 pargs_hold(p2->p_args); 472 PROC_UNLOCK(p1); 473 474 bzero(&p2->p_startzero, 475 __rangeof(struct proc, p_startzero, p_endzero)); 476 477 p2->p_ucred = crhold(td->td_ucred); 478 479 /* Tell the prison that we exist. */ 480 prison_proc_hold(p2->p_ucred->cr_prison); 481 482 PROC_UNLOCK(p2); 483 484 /* 485 * Malloc things while we don't hold any locks. 486 */ 487 if (flags & RFSIGSHARE) 488 newsigacts = NULL; 489 else 490 newsigacts = sigacts_alloc(); 491 492 /* 493 * Copy filedesc. 494 */ 495 if (flags & RFCFDG) { 496 fd = fdinit(p1->p_fd); 497 fdtol = NULL; 498 } else if (flags & RFFDG) { 499 fd = fdcopy(p1->p_fd); 500 fdtol = NULL; 501 } else { 502 fd = fdshare(p1->p_fd); 503 if (p1->p_fdtol == NULL) 504 p1->p_fdtol = 505 filedesc_to_leader_alloc(NULL, 506 NULL, 507 p1->p_leader); 508 if ((flags & RFTHREAD) != 0) { 509 /* 510 * Shared file descriptor table and 511 * shared process leaders. 512 */ 513 fdtol = p1->p_fdtol; 514 FILEDESC_XLOCK(p1->p_fd); 515 fdtol->fdl_refcount++; 516 FILEDESC_XUNLOCK(p1->p_fd); 517 } else { 518 /* 519 * Shared file descriptor table, and 520 * different process leaders 521 */ 522 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, 523 p1->p_fd, 524 p2); 525 } 526 } 527 /* 528 * Make a proc table entry for the new process. 529 * Start by zeroing the section of proc that is zero-initialized, 530 * then copy the section that is copied directly from the parent. 531 */ 532 533 PROC_LOCK(p2); 534 PROC_LOCK(p1); 535 536 bzero(&td2->td_startzero, 537 __rangeof(struct thread, td_startzero, td_endzero)); 538 539 bcopy(&td->td_startcopy, &td2->td_startcopy, 540 __rangeof(struct thread, td_startcopy, td_endcopy)); 541 542 bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name)); 543 td2->td_sigstk = td->td_sigstk; 544 td2->td_sigmask = td->td_sigmask; 545 td2->td_flags = TDF_INMEM; 546 td2->td_lend_user_pri = PRI_MAX; 547 548 #ifdef VIMAGE 549 td2->td_vnet = NULL; 550 td2->td_vnet_lpush = NULL; 551 #endif 552 553 /* 554 * Duplicate sub-structures as needed. 555 * Increase reference counts on shared objects. 556 */ 557 p2->p_flag = P_INMEM; 558 p2->p_swtick = ticks; 559 if (p1->p_flag & P_PROFIL) 560 startprofclock(p2); 561 td2->td_ucred = crhold(p2->p_ucred); 562 563 if (flags & RFSIGSHARE) { 564 p2->p_sigacts = sigacts_hold(p1->p_sigacts); 565 } else { 566 sigacts_copy(newsigacts, p1->p_sigacts); 567 p2->p_sigacts = newsigacts; 568 } 569 if (flags & RFLINUXTHPN) 570 p2->p_sigparent = SIGUSR1; 571 else 572 p2->p_sigparent = SIGCHLD; 573 574 p2->p_textvp = p1->p_textvp; 575 p2->p_fd = fd; 576 p2->p_fdtol = fdtol; 577 578 /* 579 * p_limit is copy-on-write. Bump its refcount. 580 */ 581 lim_fork(p1, p2); 582 583 pstats_fork(p1->p_stats, p2->p_stats); 584 585 PROC_UNLOCK(p1); 586 PROC_UNLOCK(p2); 587 588 /* Bump references to the text vnode (for procfs) */ 589 if (p2->p_textvp) 590 vref(p2->p_textvp); 591 592 /* 593 * Set up linkage for kernel based threading. 594 */ 595 if ((flags & RFTHREAD) != 0) { 596 mtx_lock(&ppeers_lock); 597 p2->p_peers = p1->p_peers; 598 p1->p_peers = p2; 599 p2->p_leader = p1->p_leader; 600 mtx_unlock(&ppeers_lock); 601 PROC_LOCK(p1->p_leader); 602 if ((p1->p_leader->p_flag & P_WEXIT) != 0) { 603 PROC_UNLOCK(p1->p_leader); 604 /* 605 * The task leader is exiting, so process p1 is 606 * going to be killed shortly. Since p1 obviously 607 * isn't dead yet, we know that the leader is either 608 * sending SIGKILL's to all the processes in this 609 * task or is sleeping waiting for all the peers to 610 * exit. We let p1 complete the fork, but we need 611 * to go ahead and kill the new process p2 since 612 * the task leader may not get a chance to send 613 * SIGKILL to it. We leave it on the list so that 614 * the task leader will wait for this new process 615 * to commit suicide. 616 */ 617 PROC_LOCK(p2); 618 psignal(p2, SIGKILL); 619 PROC_UNLOCK(p2); 620 } else 621 PROC_UNLOCK(p1->p_leader); 622 } else { 623 p2->p_peers = NULL; 624 p2->p_leader = p2; 625 } 626 627 sx_xlock(&proctree_lock); 628 PGRP_LOCK(p1->p_pgrp); 629 PROC_LOCK(p2); 630 PROC_LOCK(p1); 631 632 /* 633 * Preserve some more flags in subprocess. P_PROFIL has already 634 * been preserved. 635 */ 636 p2->p_flag |= p1->p_flag & P_SUGID; 637 td2->td_pflags |= td->td_pflags & TDP_ALTSTACK; 638 SESS_LOCK(p1->p_session); 639 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 640 p2->p_flag |= P_CONTROLT; 641 SESS_UNLOCK(p1->p_session); 642 if (flags & RFPPWAIT) 643 p2->p_flag |= P_PPWAIT; 644 645 p2->p_pgrp = p1->p_pgrp; 646 LIST_INSERT_AFTER(p1, p2, p_pglist); 647 PGRP_UNLOCK(p1->p_pgrp); 648 LIST_INIT(&p2->p_children); 649 650 callout_init(&p2->p_itcallout, CALLOUT_MPSAFE); 651 652 #ifdef KTRACE 653 ktrprocfork(p1, p2); 654 #endif 655 656 /* 657 * If PF_FORK is set, the child process inherits the 658 * procfs ioctl flags from its parent. 659 */ 660 if (p1->p_pfsflags & PF_FORK) { 661 p2->p_stops = p1->p_stops; 662 p2->p_pfsflags = p1->p_pfsflags; 663 } 664 665 /* 666 * This begins the section where we must prevent the parent 667 * from being swapped. 668 */ 669 _PHOLD(p1); 670 PROC_UNLOCK(p1); 671 672 /* 673 * Attach the new process to its parent. 674 * 675 * If RFNOWAIT is set, the newly created process becomes a child 676 * of init. This effectively disassociates the child from the 677 * parent. 678 */ 679 if (flags & RFNOWAIT) 680 pptr = initproc; 681 else 682 pptr = p1; 683 p2->p_pptr = pptr; 684 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 685 sx_xunlock(&proctree_lock); 686 687 /* Inform accounting that we have forked. */ 688 p2->p_acflag = AFORK; 689 PROC_UNLOCK(p2); 690 691 /* 692 * Finish creating the child process. It will return via a different 693 * execution path later. (ie: directly into user mode) 694 */ 695 vm_forkproc(td, p2, td2, vm2, flags); 696 697 if (flags == (RFFDG | RFPROC)) { 698 PCPU_INC(cnt.v_forks); 699 PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize + 700 p2->p_vmspace->vm_ssize); 701 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 702 PCPU_INC(cnt.v_vforks); 703 PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize + 704 p2->p_vmspace->vm_ssize); 705 } else if (p1 == &proc0) { 706 PCPU_INC(cnt.v_kthreads); 707 PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize + 708 p2->p_vmspace->vm_ssize); 709 } else { 710 PCPU_INC(cnt.v_rforks); 711 PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize + 712 p2->p_vmspace->vm_ssize); 713 } 714 715 /* 716 * Both processes are set up, now check if any loadable modules want 717 * to adjust anything. 718 * What if they have an error? XXX 719 */ 720 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags); 721 722 /* 723 * Set the child start time and mark the process as being complete. 724 */ 725 microuptime(&p2->p_stats->p_start); 726 PROC_SLOCK(p2); 727 p2->p_state = PRS_NORMAL; 728 PROC_SUNLOCK(p2); 729 #ifdef KDTRACE_HOOKS 730 /* 731 * Tell the DTrace fasttrap provider about the new process 732 * if it has registered an interest. We have to do this only after 733 * p_state is PRS_NORMAL since the fasttrap module will use pfind() 734 * later on. 735 */ 736 if (dtrace_fasttrap_fork) { 737 PROC_LOCK(p1); 738 PROC_LOCK(p2); 739 dtrace_fasttrap_fork(p1, p2); 740 PROC_UNLOCK(p2); 741 PROC_UNLOCK(p1); 742 } 743 #endif 744 745 /* 746 * If RFSTOPPED not requested, make child runnable and add to 747 * run queue. 748 */ 749 if ((flags & RFSTOPPED) == 0) { 750 thread_lock(td2); 751 TD_SET_CAN_RUN(td2); 752 sched_add(td2, SRQ_BORING); 753 thread_unlock(td2); 754 } 755 756 /* 757 * Now can be swapped. 758 */ 759 PROC_LOCK(p1); 760 _PRELE(p1); 761 PROC_UNLOCK(p1); 762 763 /* 764 * Tell any interested parties about the new process. 765 */ 766 knote_fork(&p1->p_klist, p2->p_pid); 767 SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0); 768 769 /* 770 * Preserve synchronization semantics of vfork. If waiting for 771 * child to exec or exit, set P_PPWAIT on child, and sleep on our 772 * proc (in case of exit). 773 */ 774 PROC_LOCK(p2); 775 while (p2->p_flag & P_PPWAIT) 776 cv_wait(&p2->p_pwait, &p2->p_mtx); 777 PROC_UNLOCK(p2); 778 779 /* 780 * Return child proc pointer to parent. 781 */ 782 *procp = p2; 783 return (0); 784 fail: 785 sx_sunlock(&proctree_lock); 786 if (ppsratecheck(&lastfail, &curfail, 1)) 787 printf("maxproc limit exceeded by uid %i, please see tuning(7) and login.conf(5).\n", 788 td->td_ucred->cr_ruid); 789 sx_xunlock(&allproc_lock); 790 #ifdef MAC 791 mac_proc_destroy(newproc); 792 #endif 793 fail1: 794 if (vm2 != NULL) 795 vmspace_free(vm2); 796 uma_zfree(proc_zone, newproc); 797 pause("fork", hz / 2); 798 return (error); 799 } 800 801 /* 802 * Handle the return of a child process from fork1(). This function 803 * is called from the MD fork_trampoline() entry point. 804 */ 805 void 806 fork_exit(void (*callout)(void *, struct trapframe *), void *arg, 807 struct trapframe *frame) 808 { 809 struct proc *p; 810 struct thread *td; 811 struct thread *dtd; 812 813 td = curthread; 814 p = td->td_proc; 815 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new")); 816 817 CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)", 818 td, td->td_sched, p->p_pid, td->td_name); 819 820 sched_fork_exit(td); 821 /* 822 * Processes normally resume in mi_switch() after being 823 * cpu_switch()'ed to, but when children start up they arrive here 824 * instead, so we must do much the same things as mi_switch() would. 825 */ 826 if ((dtd = PCPU_GET(deadthread))) { 827 PCPU_SET(deadthread, NULL); 828 thread_stash(dtd); 829 } 830 thread_unlock(td); 831 832 /* 833 * cpu_set_fork_handler intercepts this function call to 834 * have this call a non-return function to stay in kernel mode. 835 * initproc has its own fork handler, but it does return. 836 */ 837 KASSERT(callout != NULL, ("NULL callout in fork_exit")); 838 callout(arg, frame); 839 840 /* 841 * Check if a kernel thread misbehaved and returned from its main 842 * function. 843 */ 844 if (p->p_flag & P_KTHREAD) { 845 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 846 td->td_name, p->p_pid); 847 kproc_exit(0); 848 } 849 mtx_assert(&Giant, MA_NOTOWNED); 850 851 EVENTHANDLER_INVOKE(schedtail, p); 852 } 853 854 /* 855 * Simplified back end of syscall(), used when returning from fork() 856 * directly into user mode. Giant is not held on entry, and must not 857 * be held on return. This function is passed in to fork_exit() as the 858 * first parameter and is called when returning to a new userland process. 859 */ 860 void 861 fork_return(struct thread *td, struct trapframe *frame) 862 { 863 864 userret(td, frame); 865 #ifdef KTRACE 866 if (KTRPOINT(td, KTR_SYSRET)) 867 ktrsysret(SYS_fork, 0, 0); 868 #endif 869 mtx_assert(&Giant, MA_NOTOWNED); 870 } 871