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