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#include "opt_procdesc.h" 44 45#include <sys/param.h> 46#include <sys/systm.h> 47#include <sys/sysproto.h> 48#include <sys/eventhandler.h> 49#include <sys/fcntl.h> 50#include <sys/filedesc.h> 51#include <sys/jail.h> 52#include <sys/kernel.h> 53#include <sys/kthread.h> 54#include <sys/sysctl.h> 55#include <sys/lock.h> 56#include <sys/malloc.h> 57#include <sys/mutex.h> 58#include <sys/priv.h> 59#include <sys/proc.h> 60#include <sys/procdesc.h> 61#include <sys/pioctl.h> 62#include <sys/racct.h> 63#include <sys/resourcevar.h> 64#include <sys/sched.h> 65#include <sys/syscall.h> 66#include <sys/vmmeter.h> 67#include <sys/vnode.h> 68#include <sys/acct.h> 69#include <sys/ktr.h> 70#include <sys/ktrace.h> 71#include <sys/unistd.h> 72#include <sys/sdt.h> 73#include <sys/sx.h> 74#include <sys/sysent.h> 75#include <sys/signalvar.h> 76 77#include <security/audit/audit.h> 78#include <security/mac/mac_framework.h> 79 80#include <vm/vm.h> 81#include <vm/pmap.h> 82#include <vm/vm_map.h> 83#include <vm/vm_extern.h> 84#include <vm/uma.h> 85 86#ifdef KDTRACE_HOOKS 87#include <sys/dtrace_bsd.h> 88dtrace_fork_func_t dtrace_fasttrap_fork; 89#endif 90 91SDT_PROVIDER_DECLARE(proc); 92SDT_PROBE_DEFINE3(proc, kernel, , create, "struct proc *", 93 "struct proc *", "int"); 94 95#ifndef _SYS_SYSPROTO_H_ 96struct fork_args { 97 int dummy; 98}; 99#endif 100 101/* ARGSUSED */ 102int 103sys_fork(struct thread *td, struct fork_args *uap) 104{ 105 int error; 106 struct proc *p2; 107 108 error = fork1(td, RFFDG | RFPROC, 0, &p2, NULL, 0); 109 if (error == 0) { 110 td->td_retval[0] = p2->p_pid; 111 td->td_retval[1] = 0; 112 } 113 return (error); 114} 115 116/* ARGUSED */ 117int 118sys_pdfork(td, uap) 119 struct thread *td; 120 struct pdfork_args *uap; 121{ 122#ifdef PROCDESC 123 int error, fd; 124 struct proc *p2; 125 126 /* 127 * It is necessary to return fd by reference because 0 is a valid file 128 * descriptor number, and the child needs to be able to distinguish 129 * itself from the parent using the return value. 130 */ 131 error = fork1(td, RFFDG | RFPROC | RFPROCDESC, 0, &p2, 132 &fd, uap->flags); 133 if (error == 0) { 134 td->td_retval[0] = p2->p_pid; 135 td->td_retval[1] = 0; 136 error = copyout(&fd, uap->fdp, sizeof(fd)); 137 } 138 return (error); 139#else 140 return (ENOSYS); 141#endif 142} 143 144/* ARGSUSED */ 145int 146sys_vfork(struct thread *td, struct vfork_args *uap) 147{ 148 int error, flags; 149 struct proc *p2; 150 151#ifdef XEN 152 flags = RFFDG | RFPROC; /* validate that this is still an issue */ 153#else 154 flags = RFFDG | RFPROC | RFPPWAIT | RFMEM; 155#endif 156 error = fork1(td, flags, 0, &p2, NULL, 0); 157 if (error == 0) { 158 td->td_retval[0] = p2->p_pid; 159 td->td_retval[1] = 0; 160 } 161 return (error); 162} 163 164int 165sys_rfork(struct thread *td, struct rfork_args *uap) 166{ 167 struct proc *p2; 168 int error; 169 170 /* Don't allow kernel-only flags. */ 171 if ((uap->flags & RFKERNELONLY) != 0) 172 return (EINVAL); 173 174 AUDIT_ARG_FFLAGS(uap->flags); 175 error = fork1(td, uap->flags, 0, &p2, NULL, 0); 176 if (error == 0) { 177 td->td_retval[0] = p2 ? p2->p_pid : 0; 178 td->td_retval[1] = 0; 179 } 180 return (error); 181} 182 183int nprocs = 1; /* process 0 */ 184int lastpid = 0; 185SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0, 186 "Last used PID"); 187 188/* 189 * Random component to lastpid generation. We mix in a random factor to make 190 * it a little harder to predict. We sanity check the modulus value to avoid 191 * doing it in critical paths. Don't let it be too small or we pointlessly 192 * waste randomness entropy, and don't let it be impossibly large. Using a 193 * modulus that is too big causes a LOT more process table scans and slows 194 * down fork processing as the pidchecked caching is defeated. 195 */ 196static int randompid = 0; 197 198static int 199sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 200{ 201 int error, pid; 202 203 error = sysctl_wire_old_buffer(req, sizeof(int)); 204 if (error != 0) 205 return(error); 206 sx_xlock(&allproc_lock); 207 pid = randompid; 208 error = sysctl_handle_int(oidp, &pid, 0, req); 209 if (error == 0 && req->newptr != NULL) { 210 if (pid < 0 || pid > pid_max - 100) /* out of range */ 211 pid = pid_max - 100; 212 else if (pid < 2) /* NOP */ 213 pid = 0; 214 else if (pid < 100) /* Make it reasonable */ 215 pid = 100; 216 randompid = pid; 217 } 218 sx_xunlock(&allproc_lock); 219 return (error); 220} 221 222SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 223 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 224 225static int 226fork_findpid(int flags) 227{ 228 struct proc *p; 229 int trypid; 230 static int pidchecked = 0; 231 232 /* 233 * Requires allproc_lock in order to iterate over the list 234 * of processes, and proctree_lock to access p_pgrp. 235 */ 236 sx_assert(&allproc_lock, SX_LOCKED); 237 sx_assert(&proctree_lock, SX_LOCKED); 238 239 /* 240 * Find an unused process ID. We remember a range of unused IDs 241 * ready to use (from lastpid+1 through pidchecked-1). 242 * 243 * If RFHIGHPID is set (used during system boot), do not allocate 244 * low-numbered pids. 245 */ 246 trypid = lastpid + 1; 247 if (flags & RFHIGHPID) { 248 if (trypid < 10) 249 trypid = 10; 250 } else { 251 if (randompid) 252 trypid += arc4random() % randompid; 253 } 254retry: 255 /* 256 * If the process ID prototype has wrapped around, 257 * restart somewhat above 0, as the low-numbered procs 258 * tend to include daemons that don't exit. 259 */ 260 if (trypid >= pid_max) { 261 trypid = trypid % pid_max; 262 if (trypid < 100) 263 trypid += 100; 264 pidchecked = 0; 265 } 266 if (trypid >= pidchecked) { 267 int doingzomb = 0; 268 269 pidchecked = PID_MAX; 270 /* 271 * Scan the active and zombie procs to check whether this pid 272 * is in use. Remember the lowest pid that's greater 273 * than trypid, so we can avoid checking for a while. 274 */ 275 p = LIST_FIRST(&allproc); 276again: 277 for (; p != NULL; p = LIST_NEXT(p, p_list)) { 278 while (p->p_pid == trypid || 279 (p->p_pgrp != NULL && 280 (p->p_pgrp->pg_id == trypid || 281 (p->p_session != NULL && 282 p->p_session->s_sid == trypid)))) { 283 trypid++; 284 if (trypid >= pidchecked) 285 goto retry; 286 } 287 if (p->p_pid > trypid && pidchecked > p->p_pid) 288 pidchecked = p->p_pid; 289 if (p->p_pgrp != NULL) { 290 if (p->p_pgrp->pg_id > trypid && 291 pidchecked > p->p_pgrp->pg_id) 292 pidchecked = p->p_pgrp->pg_id; 293 if (p->p_session != NULL && 294 p->p_session->s_sid > trypid && 295 pidchecked > p->p_session->s_sid) 296 pidchecked = p->p_session->s_sid; 297 } 298 } 299 if (!doingzomb) { 300 doingzomb = 1; 301 p = LIST_FIRST(&zombproc); 302 goto again; 303 } 304 } 305 306 /* 307 * RFHIGHPID does not mess with the lastpid counter during boot. 308 */ 309 if (flags & RFHIGHPID) 310 pidchecked = 0; 311 else 312 lastpid = trypid; 313 314 return (trypid); 315} 316 317static int 318fork_norfproc(struct thread *td, int flags) 319{ 320 int error; 321 struct proc *p1; 322 323 KASSERT((flags & RFPROC) == 0, 324 ("fork_norfproc called with RFPROC set")); 325 p1 = td->td_proc; 326 327 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 328 (flags & (RFCFDG | RFFDG))) { 329 PROC_LOCK(p1); 330 if (thread_single(SINGLE_BOUNDARY)) { 331 PROC_UNLOCK(p1); 332 return (ERESTART); 333 } 334 PROC_UNLOCK(p1); 335 } 336 337 error = vm_forkproc(td, NULL, NULL, NULL, flags); 338 if (error) 339 goto fail; 340 341 /* 342 * Close all file descriptors. 343 */ 344 if (flags & RFCFDG) { 345 struct filedesc *fdtmp; 346 fdtmp = fdinit(td->td_proc->p_fd); 347 fdfree(td); 348 p1->p_fd = fdtmp; 349 } 350 351 /* 352 * Unshare file descriptors (from parent). 353 */ 354 if (flags & RFFDG) 355 fdunshare(p1, td); 356 357fail: 358 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 359 (flags & (RFCFDG | RFFDG))) { 360 PROC_LOCK(p1); 361 thread_single_end(); 362 PROC_UNLOCK(p1); 363 } 364 return (error); 365} 366 367static void 368do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2, 369 struct vmspace *vm2, int pdflags) 370{ 371 struct proc *p1, *pptr; 372 int p2_held, trypid; 373 struct filedesc *fd; 374 struct filedesc_to_leader *fdtol; 375 struct sigacts *newsigacts; 376 377 sx_assert(&proctree_lock, SX_SLOCKED); 378 sx_assert(&allproc_lock, SX_XLOCKED); 379 380 p2_held = 0; 381 p1 = td->td_proc; 382 383 /* 384 * Increment the nprocs resource before blocking can occur. There 385 * are hard-limits as to the number of processes that can run. 386 */ 387 nprocs++; 388 389 trypid = fork_findpid(flags); 390 391 sx_sunlock(&proctree_lock); 392 393 p2->p_state = PRS_NEW; /* protect against others */ 394 p2->p_pid = trypid; 395 AUDIT_ARG_PID(p2->p_pid); 396 LIST_INSERT_HEAD(&allproc, p2, p_list); 397 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 398 tidhash_add(td2); 399 PROC_LOCK(p2); 400 PROC_LOCK(p1); 401 402 sx_xunlock(&allproc_lock); 403 404 bcopy(&p1->p_startcopy, &p2->p_startcopy, 405 __rangeof(struct proc, p_startcopy, p_endcopy)); 406 pargs_hold(p2->p_args); 407 PROC_UNLOCK(p1); 408 409 bzero(&p2->p_startzero, 410 __rangeof(struct proc, p_startzero, p_endzero)); 411 412 p2->p_ucred = crhold(td->td_ucred); 413 414 /* Tell the prison that we exist. */ 415 prison_proc_hold(p2->p_ucred->cr_prison); 416 417 PROC_UNLOCK(p2); 418 419 /* 420 * Malloc things while we don't hold any locks. 421 */ 422 if (flags & RFSIGSHARE) 423 newsigacts = NULL; 424 else 425 newsigacts = sigacts_alloc(); 426 427 /* 428 * Copy filedesc. 429 */ 430 if (flags & RFCFDG) { 431 fd = fdinit(p1->p_fd); 432 fdtol = NULL; 433 } else if (flags & RFFDG) { 434 fd = fdcopy(p1->p_fd); 435 fdtol = NULL; 436 } else { 437 fd = fdshare(p1->p_fd); 438 if (p1->p_fdtol == NULL) 439 p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL, 440 p1->p_leader); 441 if ((flags & RFTHREAD) != 0) { 442 /* 443 * Shared file descriptor table, and shared 444 * process leaders. 445 */ 446 fdtol = p1->p_fdtol; 447 FILEDESC_XLOCK(p1->p_fd); 448 fdtol->fdl_refcount++; 449 FILEDESC_XUNLOCK(p1->p_fd); 450 } else { 451 /* 452 * Shared file descriptor table, and different 453 * process leaders. 454 */ 455 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, 456 p1->p_fd, p2); 457 } 458 } 459 /* 460 * Make a proc table entry for the new process. 461 * Start by zeroing the section of proc that is zero-initialized, 462 * then copy the section that is copied directly from the parent. 463 */ 464 465 PROC_LOCK(p2); 466 PROC_LOCK(p1); 467 468 bzero(&td2->td_startzero, 469 __rangeof(struct thread, td_startzero, td_endzero)); 470 471 bcopy(&td->td_startcopy, &td2->td_startcopy, 472 __rangeof(struct thread, td_startcopy, td_endcopy)); 473 474 bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name)); 475 td2->td_sigstk = td->td_sigstk; 476 td2->td_sigmask = td->td_sigmask; 477 td2->td_flags = TDF_INMEM; 478 td2->td_lend_user_pri = PRI_MAX; 479 480#ifdef VIMAGE 481 td2->td_vnet = NULL; 482 td2->td_vnet_lpush = NULL; 483#endif 484 485 /* 486 * Allow the scheduler to initialize the child. 487 */ 488 thread_lock(td); 489 sched_fork(td, td2); 490 thread_unlock(td); 491 492 /* 493 * Duplicate sub-structures as needed. 494 * Increase reference counts on shared objects. 495 */ 496 p2->p_flag = P_INMEM; 497 p2->p_flag2 = 0; 498 p2->p_swtick = ticks; 499 if (p1->p_flag & P_PROFIL) 500 startprofclock(p2); 501 td2->td_ucred = crhold(p2->p_ucred); 502 503 if (flags & RFSIGSHARE) { 504 p2->p_sigacts = sigacts_hold(p1->p_sigacts); 505 } else { 506 sigacts_copy(newsigacts, p1->p_sigacts); 507 p2->p_sigacts = newsigacts; 508 } 509 510 if (flags & RFTSIGZMB) 511 p2->p_sigparent = RFTSIGNUM(flags); 512 else if (flags & RFLINUXTHPN) 513 p2->p_sigparent = SIGUSR1; 514 else 515 p2->p_sigparent = SIGCHLD; 516 517 p2->p_textvp = p1->p_textvp; 518 p2->p_fd = fd; 519 p2->p_fdtol = fdtol; 520 521 if (p1->p_flag2 & P2_INHERIT_PROTECTED) { 522 p2->p_flag |= P_PROTECTED; 523 p2->p_flag2 |= P2_INHERIT_PROTECTED; 524 } 525 526 /* 527 * p_limit is copy-on-write. Bump its refcount. 528 */ 529 lim_fork(p1, p2); 530 531 pstats_fork(p1->p_stats, p2->p_stats); 532 533 PROC_UNLOCK(p1); 534 PROC_UNLOCK(p2); 535 536 /* Bump references to the text vnode (for procfs). */ 537 if (p2->p_textvp) 538 vref(p2->p_textvp); 539 540 /* 541 * Set up linkage for kernel based threading. 542 */ 543 if ((flags & RFTHREAD) != 0) { 544 mtx_lock(&ppeers_lock); 545 p2->p_peers = p1->p_peers; 546 p1->p_peers = p2; 547 p2->p_leader = p1->p_leader; 548 mtx_unlock(&ppeers_lock); 549 PROC_LOCK(p1->p_leader); 550 if ((p1->p_leader->p_flag & P_WEXIT) != 0) { 551 PROC_UNLOCK(p1->p_leader); 552 /* 553 * The task leader is exiting, so process p1 is 554 * going to be killed shortly. Since p1 obviously 555 * isn't dead yet, we know that the leader is either 556 * sending SIGKILL's to all the processes in this 557 * task or is sleeping waiting for all the peers to 558 * exit. We let p1 complete the fork, but we need 559 * to go ahead and kill the new process p2 since 560 * the task leader may not get a chance to send 561 * SIGKILL to it. We leave it on the list so that 562 * the task leader will wait for this new process 563 * to commit suicide. 564 */ 565 PROC_LOCK(p2); 566 kern_psignal(p2, SIGKILL); 567 PROC_UNLOCK(p2); 568 } else 569 PROC_UNLOCK(p1->p_leader); 570 } else { 571 p2->p_peers = NULL; 572 p2->p_leader = p2; 573 } 574 575 sx_xlock(&proctree_lock); 576 PGRP_LOCK(p1->p_pgrp); 577 PROC_LOCK(p2); 578 PROC_LOCK(p1); 579 580 /* 581 * Preserve some more flags in subprocess. P_PROFIL has already 582 * been preserved. 583 */ 584 p2->p_flag |= p1->p_flag & P_SUGID; 585 td2->td_pflags |= td->td_pflags & TDP_ALTSTACK; 586 SESS_LOCK(p1->p_session); 587 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 588 p2->p_flag |= P_CONTROLT; 589 SESS_UNLOCK(p1->p_session); 590 if (flags & RFPPWAIT) 591 p2->p_flag |= P_PPWAIT; 592 593 p2->p_pgrp = p1->p_pgrp; 594 LIST_INSERT_AFTER(p1, p2, p_pglist); 595 PGRP_UNLOCK(p1->p_pgrp); 596 LIST_INIT(&p2->p_children); 597 LIST_INIT(&p2->p_orphans); 598 599 callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0); 600 601 /* 602 * If PF_FORK is set, the child process inherits the 603 * procfs ioctl flags from its parent. 604 */ 605 if (p1->p_pfsflags & PF_FORK) { 606 p2->p_stops = p1->p_stops; 607 p2->p_pfsflags = p1->p_pfsflags; 608 } 609 610 /* 611 * This begins the section where we must prevent the parent 612 * from being swapped. 613 */ 614 _PHOLD(p1); 615 PROC_UNLOCK(p1); 616 617 /* 618 * Attach the new process to its parent. 619 * 620 * If RFNOWAIT is set, the newly created process becomes a child 621 * of init. This effectively disassociates the child from the 622 * parent. 623 */ 624 if (flags & RFNOWAIT) 625 pptr = initproc; 626 else 627 pptr = p1; 628 p2->p_pptr = pptr; 629 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 630 sx_xunlock(&proctree_lock); 631 632 /* Inform accounting that we have forked. */ 633 p2->p_acflag = AFORK; 634 PROC_UNLOCK(p2); 635 636#ifdef KTRACE 637 ktrprocfork(p1, p2); 638#endif 639 640 /* 641 * Finish creating the child process. It will return via a different 642 * execution path later. (ie: directly into user mode) 643 */ 644 vm_forkproc(td, p2, td2, vm2, flags); 645 646 if (flags == (RFFDG | RFPROC)) { 647 PCPU_INC(cnt.v_forks); 648 PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize + 649 p2->p_vmspace->vm_ssize); 650 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 651 PCPU_INC(cnt.v_vforks); 652 PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize + 653 p2->p_vmspace->vm_ssize); 654 } else if (p1 == &proc0) { 655 PCPU_INC(cnt.v_kthreads); 656 PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize + 657 p2->p_vmspace->vm_ssize); 658 } else { 659 PCPU_INC(cnt.v_rforks); 660 PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize + 661 p2->p_vmspace->vm_ssize); 662 } 663 664#ifdef PROCDESC 665 /* 666 * Associate the process descriptor with the process before anything 667 * can happen that might cause that process to need the descriptor. 668 * However, don't do this until after fork(2) can no longer fail. 669 */ 670 if (flags & RFPROCDESC) 671 procdesc_new(p2, pdflags); 672#endif 673 674 /* 675 * Both processes are set up, now check if any loadable modules want 676 * to adjust anything. 677 */ 678 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags); 679 680 /* 681 * Set the child start time and mark the process as being complete. 682 */ 683 PROC_LOCK(p2); 684 PROC_LOCK(p1); 685 microuptime(&p2->p_stats->p_start); 686 PROC_SLOCK(p2); 687 p2->p_state = PRS_NORMAL; 688 PROC_SUNLOCK(p2); 689 690#ifdef KDTRACE_HOOKS 691 /* 692 * Tell the DTrace fasttrap provider about the new process so that any 693 * tracepoints inherited from the parent can be removed. We have to do 694 * this only after p_state is PRS_NORMAL since the fasttrap module will 695 * use pfind() later on. 696 */ 697 if ((flags & RFMEM) == 0 && dtrace_fasttrap_fork) 698 dtrace_fasttrap_fork(p1, p2); 699#endif 700 if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED | 701 P_FOLLOWFORK)) { 702 /* 703 * Arrange for debugger to receive the fork event. 704 * 705 * We can report PL_FLAG_FORKED regardless of 706 * P_FOLLOWFORK settings, but it does not make a sense 707 * for runaway child. 708 */ 709 td->td_dbgflags |= TDB_FORK; 710 td->td_dbg_forked = p2->p_pid; 711 td2->td_dbgflags |= TDB_STOPATFORK; 712 _PHOLD(p2); 713 p2_held = 1; 714 } 715 if (flags & RFPPWAIT) { 716 td->td_pflags |= TDP_RFPPWAIT; 717 td->td_rfppwait_p = p2; 718 } 719 PROC_UNLOCK(p2); 720 if ((flags & RFSTOPPED) == 0) { 721 /* 722 * If RFSTOPPED not requested, make child runnable and 723 * add to run queue. 724 */ 725 thread_lock(td2); 726 TD_SET_CAN_RUN(td2); 727 sched_add(td2, SRQ_BORING); 728 thread_unlock(td2); 729 } 730 731 /* 732 * Now can be swapped. 733 */ 734 _PRELE(p1); 735 PROC_UNLOCK(p1); 736 737 /* 738 * Tell any interested parties about the new process. 739 */ 740 knote_fork(&p1->p_klist, p2->p_pid); 741 SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0); 742 743 /* 744 * Wait until debugger is attached to child. 745 */ 746 PROC_LOCK(p2); 747 while ((td2->td_dbgflags & TDB_STOPATFORK) != 0) 748 cv_wait(&p2->p_dbgwait, &p2->p_mtx); 749 if (p2_held) 750 _PRELE(p2); 751 PROC_UNLOCK(p2); 752} 753 754int 755fork1(struct thread *td, int flags, int pages, struct proc **procp, 756 int *procdescp, int pdflags) 757{ 758 struct proc *p1; 759 struct proc *newproc; 760 int ok; 761 struct thread *td2; 762 struct vmspace *vm2; 763 vm_ooffset_t mem_charged; 764 int error; 765 static int curfail; 766 static struct timeval lastfail; 767#ifdef PROCDESC 768 struct file *fp_procdesc = NULL; 769#endif 770 771 /* Check for the undefined or unimplemented flags. */ 772 if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0) 773 return (EINVAL); 774 775 /* Signal value requires RFTSIGZMB. */ 776 if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0) 777 return (EINVAL); 778 779 /* Can't copy and clear. */ 780 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 781 return (EINVAL); 782 783 /* Check the validity of the signal number. */ 784 if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG) 785 return (EINVAL); 786 787#ifdef PROCDESC 788 if ((flags & RFPROCDESC) != 0) { 789 /* Can't not create a process yet get a process descriptor. */ 790 if ((flags & RFPROC) == 0) 791 return (EINVAL); 792 793 /* Must provide a place to put a procdesc if creating one. */ 794 if (procdescp == NULL) 795 return (EINVAL); 796 } 797#endif 798 799 p1 = td->td_proc; 800 801 /* 802 * Here we don't create a new process, but we divorce 803 * certain parts of a process from itself. 804 */ 805 if ((flags & RFPROC) == 0) { 806 *procp = NULL; 807 return (fork_norfproc(td, flags)); 808 } 809 810#ifdef PROCDESC 811 /* 812 * If required, create a process descriptor in the parent first; we 813 * will abandon it if something goes wrong. We don't finit() until 814 * later. 815 */ 816 if (flags & RFPROCDESC) { 817 error = falloc(td, &fp_procdesc, procdescp, 0); 818 if (error != 0) 819 return (error); 820 } 821#endif 822 823 mem_charged = 0; 824 vm2 = NULL; 825 if (pages == 0) 826 pages = KSTACK_PAGES; 827 /* Allocate new proc. */ 828 newproc = uma_zalloc(proc_zone, M_WAITOK); 829 td2 = FIRST_THREAD_IN_PROC(newproc); 830 if (td2 == NULL) { 831 td2 = thread_alloc(pages); 832 if (td2 == NULL) { 833 error = ENOMEM; 834 goto fail1; 835 } 836 proc_linkup(newproc, td2); 837 } else { 838 if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) { 839 if (td2->td_kstack != 0) 840 vm_thread_dispose(td2); 841 if (!thread_alloc_stack(td2, pages)) { 842 error = ENOMEM; 843 goto fail1; 844 } 845 } 846 } 847 848 if ((flags & RFMEM) == 0) { 849 vm2 = vmspace_fork(p1->p_vmspace, &mem_charged); 850 if (vm2 == NULL) { 851 error = ENOMEM; 852 goto fail1; 853 } 854 if (!swap_reserve(mem_charged)) { 855 /* 856 * The swap reservation failed. The accounting 857 * from the entries of the copied vm2 will be 858 * substracted in vmspace_free(), so force the 859 * reservation there. 860 */ 861 swap_reserve_force(mem_charged); 862 error = ENOMEM; 863 goto fail1; 864 } 865 } else 866 vm2 = NULL; 867 868 /* 869 * XXX: This is ugly; when we copy resource usage, we need to bump 870 * per-cred resource counters. 871 */ 872 newproc->p_ucred = p1->p_ucred; 873 874 /* 875 * Initialize resource accounting for the child process. 876 */ 877 error = racct_proc_fork(p1, newproc); 878 if (error != 0) { 879 error = EAGAIN; 880 goto fail1; 881 } 882 883#ifdef MAC 884 mac_proc_init(newproc); 885#endif 886 knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx); 887 STAILQ_INIT(&newproc->p_ktr); 888 889 /* We have to lock the process tree while we look for a pid. */ 890 sx_slock(&proctree_lock); 891 892 /* 893 * Although process entries are dynamically created, we still keep 894 * a global limit on the maximum number we will create. Don't allow 895 * a nonprivileged user to use the last ten processes; don't let root 896 * exceed the limit. The variable nprocs is the current number of 897 * processes, maxproc is the limit. 898 */ 899 sx_xlock(&allproc_lock); 900 if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred, 901 PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) { 902 error = EAGAIN; 903 goto fail; 904 } 905 906 /* 907 * Increment the count of procs running with this uid. Don't allow 908 * a nonprivileged user to exceed their current limit. 909 * 910 * XXXRW: Can we avoid privilege here if it's not needed? 911 */ 912 error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0); 913 if (error == 0) 914 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0); 915 else { 916 PROC_LOCK(p1); 917 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 918 lim_cur(p1, RLIMIT_NPROC)); 919 PROC_UNLOCK(p1); 920 } 921 if (ok) { 922 do_fork(td, flags, newproc, td2, vm2, pdflags); 923 924 /* 925 * Return child proc pointer to parent. 926 */ 927 *procp = newproc; 928#ifdef PROCDESC 929 if (flags & RFPROCDESC) 930 procdesc_finit(newproc->p_procdesc, fp_procdesc); 931#endif 932 racct_proc_fork_done(newproc); 933 return (0); 934 } 935 936 error = EAGAIN; 937fail: 938 sx_sunlock(&proctree_lock); 939 if (ppsratecheck(&lastfail, &curfail, 1)) 940 printf("maxproc limit exceeded by uid %u (pid %d); see tuning(7) and login.conf(5)\n", 941 td->td_ucred->cr_ruid, p1->p_pid); 942 sx_xunlock(&allproc_lock); 943#ifdef MAC 944 mac_proc_destroy(newproc); 945#endif 946 racct_proc_exit(newproc); 947fail1: 948 if (vm2 != NULL) 949 vmspace_free(vm2); 950 uma_zfree(proc_zone, newproc); 951#ifdef PROCDESC 952 if (((flags & RFPROCDESC) != 0) && (fp_procdesc != NULL)) 953 fdrop(fp_procdesc, td); 954#endif 955 pause("fork", hz / 2); 956 return (error); 957} 958 959/* 960 * Handle the return of a child process from fork1(). This function 961 * is called from the MD fork_trampoline() entry point. 962 */ 963void 964fork_exit(void (*callout)(void *, struct trapframe *), void *arg, 965 struct trapframe *frame) 966{ 967 struct proc *p; 968 struct thread *td; 969 struct thread *dtd; 970 971 td = curthread; 972 p = td->td_proc; 973 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new")); 974 975 CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)", 976 td, td->td_sched, p->p_pid, td->td_name); 977 978 sched_fork_exit(td); 979 /* 980 * Processes normally resume in mi_switch() after being 981 * cpu_switch()'ed to, but when children start up they arrive here 982 * instead, so we must do much the same things as mi_switch() would. 983 */ 984 if ((dtd = PCPU_GET(deadthread))) { 985 PCPU_SET(deadthread, NULL); 986 thread_stash(dtd); 987 } 988 thread_unlock(td); 989 990 /* 991 * cpu_set_fork_handler intercepts this function call to 992 * have this call a non-return function to stay in kernel mode. 993 * initproc has its own fork handler, but it does return. 994 */ 995 KASSERT(callout != NULL, ("NULL callout in fork_exit")); 996 callout(arg, frame); 997 998 /* 999 * Check if a kernel thread misbehaved and returned from its main 1000 * function. 1001 */ 1002 if (p->p_flag & P_KTHREAD) { 1003 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 1004 td->td_name, p->p_pid); 1005 kproc_exit(0); 1006 } 1007 mtx_assert(&Giant, MA_NOTOWNED); 1008 1009 if (p->p_sysent->sv_schedtail != NULL) 1010 (p->p_sysent->sv_schedtail)(td); 1011} 1012 1013/* 1014 * Simplified back end of syscall(), used when returning from fork() 1015 * directly into user mode. Giant is not held on entry, and must not 1016 * be held on return. This function is passed in to fork_exit() as the 1017 * first parameter and is called when returning to a new userland process. 1018 */ 1019void 1020fork_return(struct thread *td, struct trapframe *frame) 1021{ 1022 struct proc *p, *dbg; 1023 1024 if (td->td_dbgflags & TDB_STOPATFORK) { 1025 p = td->td_proc; 1026 sx_xlock(&proctree_lock); 1027 PROC_LOCK(p); 1028 if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) == 1029 (P_TRACED | P_FOLLOWFORK)) { 1030 /* 1031 * If debugger still wants auto-attach for the 1032 * parent's children, do it now. 1033 */ 1034 dbg = p->p_pptr->p_pptr; 1035 p->p_flag |= P_TRACED; 1036 p->p_oppid = p->p_pptr->p_pid; 1037 proc_reparent(p, dbg); 1038 sx_xunlock(&proctree_lock); 1039 td->td_dbgflags |= TDB_CHILD; 1040 ptracestop(td, SIGSTOP); 1041 td->td_dbgflags &= ~TDB_CHILD; 1042 } else { 1043 /* 1044 * ... otherwise clear the request. 1045 */ 1046 sx_xunlock(&proctree_lock); 1047 td->td_dbgflags &= ~TDB_STOPATFORK; 1048 cv_broadcast(&p->p_dbgwait); 1049 } 1050 PROC_UNLOCK(p); 1051 } 1052 1053 userret(td, frame); 1054 1055#ifdef KTRACE 1056 if (KTRPOINT(td, KTR_SYSRET)) 1057 ktrsysret(SYS_fork, 0, 0); 1058#endif 1059 mtx_assert(&Giant, MA_NOTOWNED); 1060} 1061