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_kstack_pages.h" 42 #include "opt_procdesc.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/fcntl.h> 49 #include <sys/filedesc.h> 50 #include <sys/jail.h> 51 #include <sys/kernel.h> 52 #include <sys/kthread.h> 53 #include <sys/sysctl.h> 54 #include <sys/lock.h> 55 #include <sys/malloc.h> 56 #include <sys/mutex.h> 57 #include <sys/priv.h> 58 #include <sys/proc.h> 59 #include <sys/procdesc.h> 60 #include <sys/pioctl.h> 61 #include <sys/racct.h> 62 #include <sys/resourcevar.h> 63 #include <sys/sched.h> 64 #include <sys/syscall.h> 65 #include <sys/vmmeter.h> 66 #include <sys/vnode.h> 67 #include <sys/acct.h> 68 #include <sys/ktr.h> 69 #include <sys/ktrace.h> 70 #include <sys/unistd.h> 71 #include <sys/sdt.h> 72 #include <sys/sx.h> 73 #include <sys/sysent.h> 74 #include <sys/signalvar.h> 75 76 #include <security/audit/audit.h> 77 #include <security/mac/mac_framework.h> 78 79 #include <vm/vm.h> 80 #include <vm/pmap.h> 81 #include <vm/vm_map.h> 82 #include <vm/vm_extern.h> 83 #include <vm/uma.h> 84 85 #ifdef KDTRACE_HOOKS 86 #include <sys/dtrace_bsd.h> 87 dtrace_fork_func_t dtrace_fasttrap_fork; 88 #endif 89 90 SDT_PROVIDER_DECLARE(proc); 91 SDT_PROBE_DEFINE3(proc, kernel, , create, create, "struct proc *", 92 "struct proc *", "int"); 93 94 #ifndef _SYS_SYSPROTO_H_ 95 struct fork_args { 96 int dummy; 97 }; 98 #endif 99 100 /* ARGSUSED */ 101 int 102 sys_fork(struct thread *td, struct fork_args *uap) 103 { 104 int error; 105 struct proc *p2; 106 107 error = fork1(td, RFFDG | RFPROC, 0, &p2, NULL, 0); 108 if (error == 0) { 109 td->td_retval[0] = p2->p_pid; 110 td->td_retval[1] = 0; 111 } 112 return (error); 113 } 114 115 /* ARGUSED */ 116 int 117 sys_pdfork(td, uap) 118 struct thread *td; 119 struct pdfork_args *uap; 120 { 121 #ifdef PROCDESC 122 int error, fd; 123 struct proc *p2; 124 125 /* 126 * It is necessary to return fd by reference because 0 is a valid file 127 * descriptor number, and the child needs to be able to distinguish 128 * itself from the parent using the return value. 129 */ 130 error = fork1(td, RFFDG | RFPROC | RFPROCDESC, 0, &p2, 131 &fd, uap->flags); 132 if (error == 0) { 133 td->td_retval[0] = p2->p_pid; 134 td->td_retval[1] = 0; 135 error = copyout(&fd, uap->fdp, sizeof(fd)); 136 } 137 return (error); 138 #else 139 return (ENOSYS); 140 #endif 141 } 142 143 /* ARGSUSED */ 144 int 145 sys_vfork(struct thread *td, struct vfork_args *uap) 146 { 147 int error, flags; 148 struct proc *p2; 149 150 flags = RFFDG | RFPROC | RFPPWAIT | RFMEM; 151 error = fork1(td, flags, 0, &p2, NULL, 0); 152 if (error == 0) { 153 td->td_retval[0] = p2->p_pid; 154 td->td_retval[1] = 0; 155 } 156 return (error); 157 } 158 159 int 160 sys_rfork(struct thread *td, struct rfork_args *uap) 161 { 162 struct proc *p2; 163 int error; 164 165 /* Don't allow kernel-only flags. */ 166 if ((uap->flags & RFKERNELONLY) != 0) 167 return (EINVAL); 168 169 AUDIT_ARG_FFLAGS(uap->flags); 170 error = fork1(td, uap->flags, 0, &p2, NULL, 0); 171 if (error == 0) { 172 td->td_retval[0] = p2 ? p2->p_pid : 0; 173 td->td_retval[1] = 0; 174 } 175 return (error); 176 } 177 178 int nprocs = 1; /* process 0 */ 179 int lastpid = 0; 180 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0, 181 "Last used PID"); 182 183 /* 184 * Random component to lastpid generation. We mix in a random factor to make 185 * it a little harder to predict. We sanity check the modulus value to avoid 186 * doing it in critical paths. Don't let it be too small or we pointlessly 187 * waste randomness entropy, and don't let it be impossibly large. Using a 188 * modulus that is too big causes a LOT more process table scans and slows 189 * down fork processing as the pidchecked caching is defeated. 190 */ 191 static int randompid = 0; 192 193 static int 194 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 195 { 196 int error, pid; 197 198 error = sysctl_wire_old_buffer(req, sizeof(int)); 199 if (error != 0) 200 return(error); 201 sx_xlock(&allproc_lock); 202 pid = randompid; 203 error = sysctl_handle_int(oidp, &pid, 0, req); 204 if (error == 0 && req->newptr != NULL) { 205 if (pid < 0 || pid > pid_max - 100) /* out of range */ 206 pid = pid_max - 100; 207 else if (pid < 2) /* NOP */ 208 pid = 0; 209 else if (pid < 100) /* Make it reasonable */ 210 pid = 100; 211 randompid = pid; 212 } 213 sx_xunlock(&allproc_lock); 214 return (error); 215 } 216 217 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 218 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 219 220 static int 221 fork_findpid(int flags) 222 { 223 struct proc *p; 224 int trypid; 225 static int pidchecked = 0; 226 227 /* 228 * Requires allproc_lock in order to iterate over the list 229 * of processes, and proctree_lock to access p_pgrp. 230 */ 231 sx_assert(&allproc_lock, SX_LOCKED); 232 sx_assert(&proctree_lock, SX_LOCKED); 233 234 /* 235 * Find an unused process ID. We remember a range of unused IDs 236 * ready to use (from lastpid+1 through pidchecked-1). 237 * 238 * If RFHIGHPID is set (used during system boot), do not allocate 239 * low-numbered pids. 240 */ 241 trypid = lastpid + 1; 242 if (flags & RFHIGHPID) { 243 if (trypid < 10) 244 trypid = 10; 245 } else { 246 if (randompid) 247 trypid += arc4random() % randompid; 248 } 249 retry: 250 /* 251 * If the process ID prototype has wrapped around, 252 * restart somewhat above 0, as the low-numbered procs 253 * tend to include daemons that don't exit. 254 */ 255 if (trypid >= pid_max) { 256 trypid = trypid % pid_max; 257 if (trypid < 100) 258 trypid += 100; 259 pidchecked = 0; 260 } 261 if (trypid >= pidchecked) { 262 int doingzomb = 0; 263 264 pidchecked = PID_MAX; 265 /* 266 * Scan the active and zombie procs to check whether this pid 267 * is in use. Remember the lowest pid that's greater 268 * than trypid, so we can avoid checking for a while. 269 */ 270 p = LIST_FIRST(&allproc); 271 again: 272 for (; p != NULL; p = LIST_NEXT(p, p_list)) { 273 while (p->p_pid == trypid || 274 (p->p_pgrp != NULL && 275 (p->p_pgrp->pg_id == trypid || 276 (p->p_session != NULL && 277 p->p_session->s_sid == trypid)))) { 278 trypid++; 279 if (trypid >= pidchecked) 280 goto retry; 281 } 282 if (p->p_pid > trypid && pidchecked > p->p_pid) 283 pidchecked = p->p_pid; 284 if (p->p_pgrp != NULL) { 285 if (p->p_pgrp->pg_id > trypid && 286 pidchecked > p->p_pgrp->pg_id) 287 pidchecked = p->p_pgrp->pg_id; 288 if (p->p_session != NULL && 289 p->p_session->s_sid > trypid && 290 pidchecked > p->p_session->s_sid) 291 pidchecked = p->p_session->s_sid; 292 } 293 } 294 if (!doingzomb) { 295 doingzomb = 1; 296 p = LIST_FIRST(&zombproc); 297 goto again; 298 } 299 } 300 301 /* 302 * RFHIGHPID does not mess with the lastpid counter during boot. 303 */ 304 if (flags & RFHIGHPID) 305 pidchecked = 0; 306 else 307 lastpid = trypid; 308 309 return (trypid); 310 } 311 312 static int 313 fork_norfproc(struct thread *td, int flags) 314 { 315 int error; 316 struct proc *p1; 317 318 KASSERT((flags & RFPROC) == 0, 319 ("fork_norfproc called with RFPROC set")); 320 p1 = td->td_proc; 321 322 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 323 (flags & (RFCFDG | RFFDG))) { 324 PROC_LOCK(p1); 325 if (thread_single(SINGLE_BOUNDARY)) { 326 PROC_UNLOCK(p1); 327 return (ERESTART); 328 } 329 PROC_UNLOCK(p1); 330 } 331 332 error = vm_forkproc(td, NULL, NULL, NULL, flags); 333 if (error) 334 goto fail; 335 336 /* 337 * Close all file descriptors. 338 */ 339 if (flags & RFCFDG) { 340 struct filedesc *fdtmp; 341 fdtmp = fdinit(td->td_proc->p_fd); 342 fdescfree(td); 343 p1->p_fd = fdtmp; 344 } 345 346 /* 347 * Unshare file descriptors (from parent). 348 */ 349 if (flags & RFFDG) 350 fdunshare(p1, td); 351 352 fail: 353 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && 354 (flags & (RFCFDG | RFFDG))) { 355 PROC_LOCK(p1); 356 thread_single_end(); 357 PROC_UNLOCK(p1); 358 } 359 return (error); 360 } 361 362 static void 363 do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2, 364 struct vmspace *vm2, int pdflags) 365 { 366 struct proc *p1, *pptr; 367 int p2_held, trypid; 368 struct filedesc *fd; 369 struct filedesc_to_leader *fdtol; 370 struct sigacts *newsigacts; 371 372 sx_assert(&proctree_lock, SX_SLOCKED); 373 sx_assert(&allproc_lock, SX_XLOCKED); 374 375 p2_held = 0; 376 p1 = td->td_proc; 377 378 /* 379 * Increment the nprocs resource before blocking can occur. There 380 * are hard-limits as to the number of processes that can run. 381 */ 382 nprocs++; 383 384 trypid = fork_findpid(flags); 385 386 sx_sunlock(&proctree_lock); 387 388 p2->p_state = PRS_NEW; /* protect against others */ 389 p2->p_pid = trypid; 390 AUDIT_ARG_PID(p2->p_pid); 391 LIST_INSERT_HEAD(&allproc, p2, p_list); 392 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 393 tidhash_add(td2); 394 PROC_LOCK(p2); 395 PROC_LOCK(p1); 396 397 sx_xunlock(&allproc_lock); 398 399 bcopy(&p1->p_startcopy, &p2->p_startcopy, 400 __rangeof(struct proc, p_startcopy, p_endcopy)); 401 pargs_hold(p2->p_args); 402 PROC_UNLOCK(p1); 403 404 bzero(&p2->p_startzero, 405 __rangeof(struct proc, p_startzero, p_endzero)); 406 407 p2->p_ucred = crhold(td->td_ucred); 408 409 /* Tell the prison that we exist. */ 410 prison_proc_hold(p2->p_ucred->cr_prison); 411 412 PROC_UNLOCK(p2); 413 414 /* 415 * Malloc things while we don't hold any locks. 416 */ 417 if (flags & RFSIGSHARE) 418 newsigacts = NULL; 419 else 420 newsigacts = sigacts_alloc(); 421 422 /* 423 * Copy filedesc. 424 */ 425 if (flags & RFCFDG) { 426 fd = fdinit(p1->p_fd); 427 fdtol = NULL; 428 } else if (flags & RFFDG) { 429 fd = fdcopy(p1->p_fd); 430 fdtol = NULL; 431 } else { 432 fd = fdshare(p1->p_fd); 433 if (p1->p_fdtol == NULL) 434 p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL, 435 p1->p_leader); 436 if ((flags & RFTHREAD) != 0) { 437 /* 438 * Shared file descriptor table, and shared 439 * process leaders. 440 */ 441 fdtol = p1->p_fdtol; 442 FILEDESC_XLOCK(p1->p_fd); 443 fdtol->fdl_refcount++; 444 FILEDESC_XUNLOCK(p1->p_fd); 445 } else { 446 /* 447 * Shared file descriptor table, and different 448 * process leaders. 449 */ 450 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, 451 p1->p_fd, p2); 452 } 453 } 454 /* 455 * Make a proc table entry for the new process. 456 * Start by zeroing the section of proc that is zero-initialized, 457 * then copy the section that is copied directly from the parent. 458 */ 459 460 PROC_LOCK(p2); 461 PROC_LOCK(p1); 462 463 bzero(&td2->td_startzero, 464 __rangeof(struct thread, td_startzero, td_endzero)); 465 466 bcopy(&td->td_startcopy, &td2->td_startcopy, 467 __rangeof(struct thread, td_startcopy, td_endcopy)); 468 469 bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name)); 470 td2->td_sigstk = td->td_sigstk; 471 td2->td_flags = TDF_INMEM; 472 td2->td_lend_user_pri = PRI_MAX; 473 474 #ifdef VIMAGE 475 td2->td_vnet = NULL; 476 td2->td_vnet_lpush = NULL; 477 #endif 478 479 /* 480 * Allow the scheduler to initialize the child. 481 */ 482 thread_lock(td); 483 sched_fork(td, td2); 484 thread_unlock(td); 485 486 /* 487 * Duplicate sub-structures as needed. 488 * Increase reference counts on shared objects. 489 */ 490 p2->p_flag = P_INMEM; 491 p2->p_flag2 = 0; 492 p2->p_swtick = ticks; 493 if (p1->p_flag & P_PROFIL) 494 startprofclock(p2); 495 td2->td_ucred = crhold(p2->p_ucred); 496 497 if (flags & RFSIGSHARE) { 498 p2->p_sigacts = sigacts_hold(p1->p_sigacts); 499 } else { 500 sigacts_copy(newsigacts, p1->p_sigacts); 501 p2->p_sigacts = newsigacts; 502 } 503 504 if (flags & RFTSIGZMB) 505 p2->p_sigparent = RFTSIGNUM(flags); 506 else if (flags & RFLINUXTHPN) 507 p2->p_sigparent = SIGUSR1; 508 else 509 p2->p_sigparent = SIGCHLD; 510 511 p2->p_textvp = p1->p_textvp; 512 p2->p_fd = fd; 513 p2->p_fdtol = fdtol; 514 515 if (p1->p_flag2 & P2_INHERIT_PROTECTED) { 516 p2->p_flag |= P_PROTECTED; 517 p2->p_flag2 |= P2_INHERIT_PROTECTED; 518 } 519 520 /* 521 * p_limit is copy-on-write. Bump its refcount. 522 */ 523 lim_fork(p1, p2); 524 525 pstats_fork(p1->p_stats, p2->p_stats); 526 527 PROC_UNLOCK(p1); 528 PROC_UNLOCK(p2); 529 530 /* Bump references to the text vnode (for procfs). */ 531 if (p2->p_textvp) 532 vref(p2->p_textvp); 533 534 /* 535 * Set up linkage for kernel based threading. 536 */ 537 if ((flags & RFTHREAD) != 0) { 538 mtx_lock(&ppeers_lock); 539 p2->p_peers = p1->p_peers; 540 p1->p_peers = p2; 541 p2->p_leader = p1->p_leader; 542 mtx_unlock(&ppeers_lock); 543 PROC_LOCK(p1->p_leader); 544 if ((p1->p_leader->p_flag & P_WEXIT) != 0) { 545 PROC_UNLOCK(p1->p_leader); 546 /* 547 * The task leader is exiting, so process p1 is 548 * going to be killed shortly. Since p1 obviously 549 * isn't dead yet, we know that the leader is either 550 * sending SIGKILL's to all the processes in this 551 * task or is sleeping waiting for all the peers to 552 * exit. We let p1 complete the fork, but we need 553 * to go ahead and kill the new process p2 since 554 * the task leader may not get a chance to send 555 * SIGKILL to it. We leave it on the list so that 556 * the task leader will wait for this new process 557 * to commit suicide. 558 */ 559 PROC_LOCK(p2); 560 kern_psignal(p2, SIGKILL); 561 PROC_UNLOCK(p2); 562 } else 563 PROC_UNLOCK(p1->p_leader); 564 } else { 565 p2->p_peers = NULL; 566 p2->p_leader = p2; 567 } 568 569 sx_xlock(&proctree_lock); 570 PGRP_LOCK(p1->p_pgrp); 571 PROC_LOCK(p2); 572 PROC_LOCK(p1); 573 574 /* 575 * Preserve some more flags in subprocess. P_PROFIL has already 576 * been preserved. 577 */ 578 p2->p_flag |= p1->p_flag & P_SUGID; 579 td2->td_pflags |= td->td_pflags & TDP_ALTSTACK; 580 SESS_LOCK(p1->p_session); 581 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 582 p2->p_flag |= P_CONTROLT; 583 SESS_UNLOCK(p1->p_session); 584 if (flags & RFPPWAIT) 585 p2->p_flag |= P_PPWAIT; 586 587 p2->p_pgrp = p1->p_pgrp; 588 LIST_INSERT_AFTER(p1, p2, p_pglist); 589 PGRP_UNLOCK(p1->p_pgrp); 590 LIST_INIT(&p2->p_children); 591 LIST_INIT(&p2->p_orphans); 592 593 callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0); 594 595 /* 596 * If PF_FORK is set, the child process inherits the 597 * procfs ioctl flags from its parent. 598 */ 599 if (p1->p_pfsflags & PF_FORK) { 600 p2->p_stops = p1->p_stops; 601 p2->p_pfsflags = p1->p_pfsflags; 602 } 603 604 /* 605 * This begins the section where we must prevent the parent 606 * from being swapped. 607 */ 608 _PHOLD(p1); 609 PROC_UNLOCK(p1); 610 611 /* 612 * Attach the new process to its parent. 613 * 614 * If RFNOWAIT is set, the newly created process becomes a child 615 * of init. This effectively disassociates the child from the 616 * parent. 617 */ 618 if (flags & RFNOWAIT) 619 pptr = initproc; 620 else 621 pptr = p1; 622 p2->p_pptr = pptr; 623 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 624 sx_xunlock(&proctree_lock); 625 626 /* Inform accounting that we have forked. */ 627 p2->p_acflag = AFORK; 628 PROC_UNLOCK(p2); 629 630 #ifdef KTRACE 631 ktrprocfork(p1, p2); 632 #endif 633 634 /* 635 * Finish creating the child process. It will return via a different 636 * execution path later. (ie: directly into user mode) 637 */ 638 vm_forkproc(td, p2, td2, vm2, flags); 639 640 if (flags == (RFFDG | RFPROC)) { 641 PCPU_INC(cnt.v_forks); 642 PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize + 643 p2->p_vmspace->vm_ssize); 644 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 645 PCPU_INC(cnt.v_vforks); 646 PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize + 647 p2->p_vmspace->vm_ssize); 648 } else if (p1 == &proc0) { 649 PCPU_INC(cnt.v_kthreads); 650 PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize + 651 p2->p_vmspace->vm_ssize); 652 } else { 653 PCPU_INC(cnt.v_rforks); 654 PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize + 655 p2->p_vmspace->vm_ssize); 656 } 657 658 #ifdef PROCDESC 659 /* 660 * Associate the process descriptor with the process before anything 661 * can happen that might cause that process to need the descriptor. 662 * However, don't do this until after fork(2) can no longer fail. 663 */ 664 if (flags & RFPROCDESC) 665 procdesc_new(p2, pdflags); 666 #endif 667 668 /* 669 * Both processes are set up, now check if any loadable modules want 670 * to adjust anything. 671 */ 672 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags); 673 674 /* 675 * Set the child start time and mark the process as being complete. 676 */ 677 PROC_LOCK(p2); 678 PROC_LOCK(p1); 679 microuptime(&p2->p_stats->p_start); 680 PROC_SLOCK(p2); 681 p2->p_state = PRS_NORMAL; 682 PROC_SUNLOCK(p2); 683 684 #ifdef KDTRACE_HOOKS 685 /* 686 * Tell the DTrace fasttrap provider about the new process 687 * if it has registered an interest. We have to do this only after 688 * p_state is PRS_NORMAL since the fasttrap module will use pfind() 689 * later on. 690 */ 691 if (dtrace_fasttrap_fork) 692 dtrace_fasttrap_fork(p1, p2); 693 #endif 694 if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED | 695 P_FOLLOWFORK)) { 696 /* 697 * Arrange for debugger to receive the fork event. 698 * 699 * We can report PL_FLAG_FORKED regardless of 700 * P_FOLLOWFORK settings, but it does not make a sense 701 * for runaway child. 702 */ 703 td->td_dbgflags |= TDB_FORK; 704 td->td_dbg_forked = p2->p_pid; 705 td2->td_dbgflags |= TDB_STOPATFORK; 706 _PHOLD(p2); 707 p2_held = 1; 708 } 709 if (flags & RFPPWAIT) { 710 td->td_pflags |= TDP_RFPPWAIT; 711 td->td_rfppwait_p = p2; 712 } 713 PROC_UNLOCK(p2); 714 if ((flags & RFSTOPPED) == 0) { 715 /* 716 * If RFSTOPPED not requested, make child runnable and 717 * add to run queue. 718 */ 719 thread_lock(td2); 720 TD_SET_CAN_RUN(td2); 721 sched_add(td2, SRQ_BORING); 722 thread_unlock(td2); 723 } 724 725 /* 726 * Now can be swapped. 727 */ 728 _PRELE(p1); 729 PROC_UNLOCK(p1); 730 731 /* 732 * Tell any interested parties about the new process. 733 */ 734 knote_fork(&p1->p_klist, p2->p_pid); 735 SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0); 736 737 /* 738 * Wait until debugger is attached to child. 739 */ 740 PROC_LOCK(p2); 741 while ((td2->td_dbgflags & TDB_STOPATFORK) != 0) 742 cv_wait(&p2->p_dbgwait, &p2->p_mtx); 743 if (p2_held) 744 _PRELE(p2); 745 PROC_UNLOCK(p2); 746 } 747 748 int 749 fork1(struct thread *td, int flags, int pages, struct proc **procp, 750 int *procdescp, int pdflags) 751 { 752 struct proc *p1; 753 struct proc *newproc; 754 int ok; 755 struct thread *td2; 756 struct vmspace *vm2; 757 vm_ooffset_t mem_charged; 758 int error; 759 static int curfail; 760 static struct timeval lastfail; 761 #ifdef PROCDESC 762 struct file *fp_procdesc = NULL; 763 #endif 764 765 /* Check for the undefined or unimplemented flags. */ 766 if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0) 767 return (EINVAL); 768 769 /* Signal value requires RFTSIGZMB. */ 770 if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0) 771 return (EINVAL); 772 773 /* Can't copy and clear. */ 774 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 775 return (EINVAL); 776 777 /* Check the validity of the signal number. */ 778 if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG) 779 return (EINVAL); 780 781 #ifdef PROCDESC 782 if ((flags & RFPROCDESC) != 0) { 783 /* Can't not create a process yet get a process descriptor. */ 784 if ((flags & RFPROC) == 0) 785 return (EINVAL); 786 787 /* Must provide a place to put a procdesc if creating one. */ 788 if (procdescp == NULL) 789 return (EINVAL); 790 } 791 #endif 792 793 p1 = td->td_proc; 794 795 /* 796 * Here we don't create a new process, but we divorce 797 * certain parts of a process from itself. 798 */ 799 if ((flags & RFPROC) == 0) { 800 *procp = NULL; 801 return (fork_norfproc(td, flags)); 802 } 803 804 #ifdef PROCDESC 805 /* 806 * If required, create a process descriptor in the parent first; we 807 * will abandon it if something goes wrong. We don't finit() until 808 * later. 809 */ 810 if (flags & RFPROCDESC) { 811 error = falloc(td, &fp_procdesc, procdescp, 0); 812 if (error != 0) 813 return (error); 814 } 815 #endif 816 817 mem_charged = 0; 818 vm2 = NULL; 819 if (pages == 0) 820 pages = KSTACK_PAGES; 821 /* Allocate new proc. */ 822 newproc = uma_zalloc(proc_zone, M_WAITOK); 823 td2 = FIRST_THREAD_IN_PROC(newproc); 824 if (td2 == NULL) { 825 td2 = thread_alloc(pages); 826 if (td2 == NULL) { 827 error = ENOMEM; 828 goto fail1; 829 } 830 proc_linkup(newproc, td2); 831 } else { 832 if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) { 833 if (td2->td_kstack != 0) 834 vm_thread_dispose(td2); 835 if (!thread_alloc_stack(td2, pages)) { 836 error = ENOMEM; 837 goto fail1; 838 } 839 } 840 } 841 842 if ((flags & RFMEM) == 0) { 843 vm2 = vmspace_fork(p1->p_vmspace, &mem_charged); 844 if (vm2 == NULL) { 845 error = ENOMEM; 846 goto fail1; 847 } 848 if (!swap_reserve(mem_charged)) { 849 /* 850 * The swap reservation failed. The accounting 851 * from the entries of the copied vm2 will be 852 * substracted in vmspace_free(), so force the 853 * reservation there. 854 */ 855 swap_reserve_force(mem_charged); 856 error = ENOMEM; 857 goto fail1; 858 } 859 } else 860 vm2 = NULL; 861 862 /* 863 * XXX: This is ugly; when we copy resource usage, we need to bump 864 * per-cred resource counters. 865 */ 866 newproc->p_ucred = p1->p_ucred; 867 868 /* 869 * Initialize resource accounting for the child process. 870 */ 871 error = racct_proc_fork(p1, newproc); 872 if (error != 0) { 873 error = EAGAIN; 874 goto fail1; 875 } 876 877 #ifdef MAC 878 mac_proc_init(newproc); 879 #endif 880 knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx); 881 STAILQ_INIT(&newproc->p_ktr); 882 883 /* We have to lock the process tree while we look for a pid. */ 884 sx_slock(&proctree_lock); 885 886 /* 887 * Although process entries are dynamically created, we still keep 888 * a global limit on the maximum number we will create. Don't allow 889 * a nonprivileged user to use the last ten processes; don't let root 890 * exceed the limit. The variable nprocs is the current number of 891 * processes, maxproc is the limit. 892 */ 893 sx_xlock(&allproc_lock); 894 if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred, 895 PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) { 896 error = EAGAIN; 897 goto fail; 898 } 899 900 /* 901 * Increment the count of procs running with this uid. Don't allow 902 * a nonprivileged user to exceed their current limit. 903 * 904 * XXXRW: Can we avoid privilege here if it's not needed? 905 */ 906 error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0); 907 if (error == 0) 908 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0); 909 else { 910 PROC_LOCK(p1); 911 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 912 lim_cur(p1, RLIMIT_NPROC)); 913 PROC_UNLOCK(p1); 914 } 915 if (ok) { 916 do_fork(td, flags, newproc, td2, vm2, pdflags); 917 918 /* 919 * Return child proc pointer to parent. 920 */ 921 *procp = newproc; 922 #ifdef PROCDESC 923 if (flags & RFPROCDESC) { 924 procdesc_finit(newproc->p_procdesc, fp_procdesc); 925 fdrop(fp_procdesc, td); 926 } 927 #endif 928 racct_proc_fork_done(newproc); 929 return (0); 930 } 931 932 error = EAGAIN; 933 fail: 934 sx_sunlock(&proctree_lock); 935 if (ppsratecheck(&lastfail, &curfail, 1)) 936 printf("maxproc limit exceeded by uid %u (pid %d); see tuning(7) and login.conf(5)\n", 937 td->td_ucred->cr_ruid, p1->p_pid); 938 sx_xunlock(&allproc_lock); 939 #ifdef MAC 940 mac_proc_destroy(newproc); 941 #endif 942 racct_proc_exit(newproc); 943 fail1: 944 if (vm2 != NULL) 945 vmspace_free(vm2); 946 uma_zfree(proc_zone, newproc); 947 #ifdef PROCDESC 948 if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) { 949 fdclose(td->td_proc->p_fd, fp_procdesc, *procdescp, td); 950 fdrop(fp_procdesc, td); 951 } 952 #endif 953 pause("fork", hz / 2); 954 return (error); 955 } 956 957 /* 958 * Handle the return of a child process from fork1(). This function 959 * is called from the MD fork_trampoline() entry point. 960 */ 961 void 962 fork_exit(void (*callout)(void *, struct trapframe *), void *arg, 963 struct trapframe *frame) 964 { 965 struct proc *p; 966 struct thread *td; 967 struct thread *dtd; 968 969 td = curthread; 970 p = td->td_proc; 971 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new")); 972 973 CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)", 974 td, td->td_sched, p->p_pid, td->td_name); 975 976 sched_fork_exit(td); 977 /* 978 * Processes normally resume in mi_switch() after being 979 * cpu_switch()'ed to, but when children start up they arrive here 980 * instead, so we must do much the same things as mi_switch() would. 981 */ 982 if ((dtd = PCPU_GET(deadthread))) { 983 PCPU_SET(deadthread, NULL); 984 thread_stash(dtd); 985 } 986 thread_unlock(td); 987 988 /* 989 * cpu_set_fork_handler intercepts this function call to 990 * have this call a non-return function to stay in kernel mode. 991 * initproc has its own fork handler, but it does return. 992 */ 993 KASSERT(callout != NULL, ("NULL callout in fork_exit")); 994 callout(arg, frame); 995 996 /* 997 * Check if a kernel thread misbehaved and returned from its main 998 * function. 999 */ 1000 if (p->p_flag & P_KTHREAD) { 1001 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 1002 td->td_name, p->p_pid); 1003 kproc_exit(0); 1004 } 1005 mtx_assert(&Giant, MA_NOTOWNED); 1006 1007 if (p->p_sysent->sv_schedtail != NULL) 1008 (p->p_sysent->sv_schedtail)(td); 1009 } 1010 1011 /* 1012 * Simplified back end of syscall(), used when returning from fork() 1013 * directly into user mode. Giant is not held on entry, and must not 1014 * be held on return. This function is passed in to fork_exit() as the 1015 * first parameter and is called when returning to a new userland process. 1016 */ 1017 void 1018 fork_return(struct thread *td, struct trapframe *frame) 1019 { 1020 struct proc *p, *dbg; 1021 1022 if (td->td_dbgflags & TDB_STOPATFORK) { 1023 p = td->td_proc; 1024 sx_xlock(&proctree_lock); 1025 PROC_LOCK(p); 1026 if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) == 1027 (P_TRACED | P_FOLLOWFORK)) { 1028 /* 1029 * If debugger still wants auto-attach for the 1030 * parent's children, do it now. 1031 */ 1032 dbg = p->p_pptr->p_pptr; 1033 p->p_flag |= P_TRACED; 1034 p->p_oppid = p->p_pptr->p_pid; 1035 proc_reparent(p, dbg); 1036 sx_xunlock(&proctree_lock); 1037 td->td_dbgflags |= TDB_CHILD; 1038 ptracestop(td, SIGSTOP); 1039 td->td_dbgflags &= ~TDB_CHILD; 1040 } else { 1041 /* 1042 * ... otherwise clear the request. 1043 */ 1044 sx_xunlock(&proctree_lock); 1045 td->td_dbgflags &= ~TDB_STOPATFORK; 1046 cv_broadcast(&p->p_dbgwait); 1047 } 1048 PROC_UNLOCK(p); 1049 } 1050 1051 userret(td, frame); 1052 1053 #ifdef KTRACE 1054 if (KTRPOINT(td, KTR_SYSRET)) 1055 ktrsysret(SYS_fork, 0, 0); 1056 #endif 1057 } 1058