1 /* 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/sys/kern/kern_exec.c,v 1.107.2.15 2002/07/30 15:40:46 nectar Exp $ 27 * $DragonFly: src/sys/kern/kern_exec.c,v 1.59 2007/07/12 21:56:22 dillon Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/sysproto.h> 33 #include <sys/kernel.h> 34 #include <sys/mount.h> 35 #include <sys/filedesc.h> 36 #include <sys/fcntl.h> 37 #include <sys/acct.h> 38 #include <sys/exec.h> 39 #include <sys/imgact.h> 40 #include <sys/imgact_elf.h> 41 #include <sys/kern_syscall.h> 42 #include <sys/wait.h> 43 #include <sys/malloc.h> 44 #include <sys/proc.h> 45 #include <sys/ktrace.h> 46 #include <sys/signalvar.h> 47 #include <sys/pioctl.h> 48 #include <sys/nlookup.h> 49 #include <sys/sfbuf.h> 50 #include <sys/sysent.h> 51 #include <sys/shm.h> 52 #include <sys/sysctl.h> 53 #include <sys/vnode.h> 54 #include <sys/vmmeter.h> 55 #include <sys/aio.h> 56 #include <sys/libkern.h> 57 58 #include <vm/vm.h> 59 #include <vm/vm_param.h> 60 #include <sys/lock.h> 61 #include <vm/pmap.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_map.h> 64 #include <vm/vm_kern.h> 65 #include <vm/vm_extern.h> 66 #include <vm/vm_object.h> 67 #include <vm/vm_pager.h> 68 69 #include <sys/user.h> 70 #include <sys/reg.h> 71 72 #include <sys/thread2.h> 73 74 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 75 MALLOC_DEFINE(M_EXECARGS, "exec-args", "Exec arguments"); 76 77 static register_t *exec_copyout_strings (struct image_params *); 78 79 /* XXX This should be vm_size_t. */ 80 static u_long ps_strings = PS_STRINGS; 81 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 82 83 /* XXX This should be vm_size_t. */ 84 static u_long usrstack = USRSTACK; 85 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 86 87 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 88 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 89 &ps_arg_cache_limit, 0, ""); 90 91 int ps_argsopen = 1; 92 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 93 94 void print_execve_args(struct image_args *args); 95 int debug_execve_args = 0; 96 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 97 0, ""); 98 99 /* 100 * Exec arguments object cache 101 */ 102 static struct objcache *exec_objcache; 103 104 static 105 void 106 exec_objcache_init(void *arg __unused) 107 { 108 exec_objcache = objcache_create_mbacked( 109 M_EXECARGS, PATH_MAX + ARG_MAX, 110 16, /* up to this many objects */ 111 2, /* minimal magazine capacity */ 112 NULL, NULL, NULL); 113 } 114 SYSINIT(exec_objcache, SI_BOOT2_MACHDEP, SI_ORDER_ANY, exec_objcache_init, 0); 115 116 /* 117 * stackgap_random specifies if the stackgap should have a random size added 118 * to it. It must be a power of 2. If non-zero, the stack gap will be 119 * calculated as: ALIGN(karc4random() & (stackgap_random - 1)). 120 */ 121 static int stackgap_random = 1024; 122 static int 123 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 124 { 125 int error, new_val; 126 new_val = stackgap_random; 127 error = sysctl_handle_int(oidp, &new_val, 0, req); 128 if (error != 0 || req->newptr == NULL) 129 return (error); 130 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 131 return (EINVAL); 132 stackgap_random = new_val; 133 134 return(0); 135 } 136 137 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 138 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 139 140 void 141 print_execve_args(struct image_args *args) 142 { 143 char *cp; 144 int ndx; 145 146 cp = args->begin_argv; 147 for (ndx = 0; ndx < args->argc; ndx++) { 148 kprintf("\targv[%d]: %s\n", ndx, cp); 149 while (*cp++ != '\0'); 150 } 151 for (ndx = 0; ndx < args->envc; ndx++) { 152 kprintf("\tenvv[%d]: %s\n", ndx, cp); 153 while (*cp++ != '\0'); 154 } 155 } 156 157 /* 158 * Each of the items is a pointer to a `const struct execsw', hence the 159 * double pointer here. 160 */ 161 static const struct execsw **execsw; 162 163 int 164 kern_execve(struct nlookupdata *nd, struct image_args *args) 165 { 166 struct thread *td = curthread; 167 struct lwp *lp = td->td_lwp; 168 struct proc *p = td->td_proc; 169 register_t *stack_base; 170 int error, len, i; 171 struct image_params image_params, *imgp; 172 struct vattr attr; 173 int (*img_first) (struct image_params *); 174 175 if (debug_execve_args) { 176 kprintf("%s()\n", __func__); 177 print_execve_args(args); 178 } 179 180 KKASSERT(p); 181 imgp = &image_params; 182 183 /* 184 * NOTE: P_INEXEC is handled by exec_new_vmspace() now. We make 185 * no modifications to the process at all until we get there. 186 * 187 * Note that multiple threads may be trying to exec at the same 188 * time. exec_new_vmspace() handles that too. 189 */ 190 191 /* 192 * Initialize part of the common data 193 */ 194 imgp->proc = p; 195 imgp->args = args; 196 imgp->attr = &attr; 197 imgp->entry_addr = 0; 198 imgp->resident = 0; 199 imgp->vmspace_destroyed = 0; 200 imgp->interpreted = 0; 201 imgp->interpreter_name[0] = 0; 202 imgp->auxargs = NULL; 203 imgp->vp = NULL; 204 imgp->firstpage = NULL; 205 imgp->ps_strings = 0; 206 imgp->image_header = NULL; 207 208 interpret: 209 210 /* 211 * Translate the file name to a vnode. Unlock the cache entry to 212 * improve parallelism for programs exec'd in parallel. 213 */ 214 if ((error = nlookup(nd)) != 0) 215 goto exec_fail; 216 error = cache_vget(&nd->nl_nch, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 217 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 218 nd->nl_flags &= ~NLC_NCPISLOCKED; 219 cache_unlock(&nd->nl_nch); 220 if (error) 221 goto exec_fail; 222 223 /* 224 * Check file permissions (also 'opens' file) 225 */ 226 error = exec_check_permissions(imgp); 227 if (error) { 228 vn_unlock(imgp->vp); 229 goto exec_fail_dealloc; 230 } 231 232 error = exec_map_first_page(imgp); 233 vn_unlock(imgp->vp); 234 if (error) 235 goto exec_fail_dealloc; 236 237 if (debug_execve_args && imgp->interpreted) { 238 kprintf(" target is interpreted -- recursive pass\n"); 239 kprintf(" interpreter: %s\n", imgp->interpreter_name); 240 print_execve_args(args); 241 } 242 243 /* 244 * If the current process has a special image activator it 245 * wants to try first, call it. For example, emulating shell 246 * scripts differently. 247 */ 248 error = -1; 249 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 250 error = img_first(imgp); 251 252 /* 253 * If the vnode has a registered vmspace, exec the vmspace 254 */ 255 if (error == -1 && imgp->vp->v_resident) { 256 error = exec_resident_imgact(imgp); 257 } 258 259 /* 260 * Loop through the list of image activators, calling each one. 261 * An activator returns -1 if there is no match, 0 on success, 262 * and an error otherwise. 263 */ 264 for (i = 0; error == -1 && execsw[i]; ++i) { 265 if (execsw[i]->ex_imgact == NULL || 266 execsw[i]->ex_imgact == img_first) { 267 continue; 268 } 269 error = (*execsw[i]->ex_imgact)(imgp); 270 } 271 272 if (error) { 273 if (error == -1) 274 error = ENOEXEC; 275 goto exec_fail_dealloc; 276 } 277 278 /* 279 * Special interpreter operation, cleanup and loop up to try to 280 * activate the interpreter. 281 */ 282 if (imgp->interpreted) { 283 exec_unmap_first_page(imgp); 284 nlookup_done(nd); 285 vrele(imgp->vp); 286 imgp->vp = NULL; 287 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 288 NLC_FOLLOW); 289 if (error) 290 goto exec_fail; 291 goto interpret; 292 } 293 294 /* 295 * Copy out strings (args and env) and initialize stack base 296 */ 297 stack_base = exec_copyout_strings(imgp); 298 p->p_vmspace->vm_minsaddr = (char *)stack_base; 299 300 /* 301 * If custom stack fixup routine present for this process 302 * let it do the stack setup. If we are running a resident 303 * image there is no auxinfo or other image activator context 304 * so don't try to add fixups to the stack. 305 * 306 * Else stuff argument count as first item on stack 307 */ 308 if (p->p_sysent->sv_fixup && imgp->resident == 0) 309 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 310 else 311 suword(--stack_base, imgp->args->argc); 312 313 /* 314 * For security and other reasons, the file descriptor table cannot 315 * be shared after an exec. 316 */ 317 if (p->p_fd->fd_refcnt > 1) { 318 struct filedesc *tmp; 319 320 tmp = fdcopy(p); 321 fdfree(p); 322 p->p_fd = tmp; 323 } 324 325 /* 326 * For security and other reasons, signal handlers cannot 327 * be shared after an exec. The new proces gets a copy of the old 328 * handlers. In execsigs(), the new process will have its signals 329 * reset. 330 */ 331 if (p->p_sigacts->ps_refcnt > 1) { 332 struct sigacts *newsigacts; 333 334 newsigacts = (struct sigacts *)kmalloc(sizeof(*newsigacts), 335 M_SUBPROC, M_WAITOK); 336 bcopy(p->p_sigacts, newsigacts, sizeof(*newsigacts)); 337 p->p_sigacts->ps_refcnt--; 338 p->p_sigacts = newsigacts; 339 p->p_sigacts->ps_refcnt = 1; 340 } 341 342 /* 343 * For security and other reasons virtual kernels cannot be 344 * inherited by an exec. This also allows a virtual kernel 345 * to fork/exec unrelated applications. 346 */ 347 if (p->p_vkernel) 348 vkernel_exit(p); 349 350 /* Stop profiling */ 351 stopprofclock(p); 352 353 /* close files on exec */ 354 fdcloseexec(p); 355 356 /* reset caught signals */ 357 execsigs(p); 358 359 /* name this process - nameiexec(p, ndp) */ 360 len = min(nd->nl_nch.ncp->nc_nlen, MAXCOMLEN); 361 bcopy(nd->nl_nch.ncp->nc_name, p->p_comm, len); 362 p->p_comm[len] = 0; 363 bcopy(p->p_comm, lp->lwp_thread->td_comm, MAXCOMLEN+1); 364 365 /* 366 * mark as execed, wakeup the process that vforked (if any) and tell 367 * it that it now has its own resources back 368 */ 369 p->p_flag |= P_EXEC; 370 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 371 p->p_flag &= ~P_PPWAIT; 372 wakeup((caddr_t)p->p_pptr); 373 } 374 375 /* 376 * Implement image setuid/setgid. 377 * 378 * Don't honor setuid/setgid if the filesystem prohibits it or if 379 * the process is being traced. 380 */ 381 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 382 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 383 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 384 (p->p_flag & P_TRACED) == 0) { 385 /* 386 * Turn off syscall tracing for set-id programs, except for 387 * root. Record any set-id flags first to make sure that 388 * we do not regain any tracing during a possible block. 389 */ 390 setsugid(); 391 if (p->p_tracenode && suser(td) != 0) { 392 ktrdestroy(&p->p_tracenode); 393 p->p_traceflag = 0; 394 } 395 /* Close any file descriptors 0..2 that reference procfs */ 396 setugidsafety(p); 397 /* Make sure file descriptors 0..2 are in use. */ 398 error = fdcheckstd(p); 399 if (error != 0) 400 goto exec_fail_dealloc; 401 /* 402 * Set the new credentials. 403 */ 404 cratom(&p->p_ucred); 405 if (attr.va_mode & VSUID) 406 change_euid(attr.va_uid); 407 if (attr.va_mode & VSGID) 408 p->p_ucred->cr_gid = attr.va_gid; 409 410 /* 411 * Clear local varsym variables 412 */ 413 varsymset_clean(&p->p_varsymset); 414 } else { 415 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 416 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 417 p->p_flag &= ~P_SUGID; 418 } 419 420 /* 421 * Implement correct POSIX saved-id behavior. 422 */ 423 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 424 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 425 cratom(&p->p_ucred); 426 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 427 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 428 } 429 430 /* 431 * Store the vp for use in procfs 432 */ 433 if (p->p_textvp) /* release old reference */ 434 vrele(p->p_textvp); 435 p->p_textvp = imgp->vp; 436 vref(p->p_textvp); 437 438 /* 439 * Notify others that we exec'd, and clear the P_INEXEC flag 440 * as we're now a bona fide freshly-execed process. 441 */ 442 KNOTE(&p->p_klist, NOTE_EXEC); 443 p->p_flag &= ~P_INEXEC; 444 445 /* 446 * If tracing the process, trap to debugger so breakpoints 447 * can be set before the program executes. 448 */ 449 STOPEVENT(p, S_EXEC, 0); 450 451 if (p->p_flag & P_TRACED) 452 ksignal(p, SIGTRAP); 453 454 /* clear "fork but no exec" flag, as we _are_ execing */ 455 p->p_acflag &= ~AFORK; 456 457 /* Set values passed into the program in registers. */ 458 exec_setregs(imgp->entry_addr, (u_long)(uintptr_t)stack_base, 459 imgp->ps_strings); 460 461 /* Free any previous argument cache */ 462 if (p->p_args && --p->p_args->ar_ref == 0) 463 FREE(p->p_args, M_PARGS); 464 p->p_args = NULL; 465 466 /* Cache arguments if they fit inside our allowance */ 467 i = imgp->args->begin_envv - imgp->args->begin_argv; 468 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 469 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 470 M_PARGS, M_WAITOK); 471 p->p_args->ar_ref = 1; 472 p->p_args->ar_length = i; 473 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 474 } 475 476 exec_fail_dealloc: 477 478 /* 479 * free various allocated resources 480 */ 481 if (imgp->firstpage) 482 exec_unmap_first_page(imgp); 483 484 if (imgp->vp) { 485 vrele(imgp->vp); 486 imgp->vp = NULL; 487 } 488 489 if (error == 0) { 490 ++mycpu->gd_cnt.v_exec; 491 return (0); 492 } 493 494 exec_fail: 495 /* 496 * we're done here, clear P_INEXEC if we were the ones that 497 * set it. Otherwise if vmspace_destroyed is still set we 498 * raced another thread and that thread is responsible for 499 * clearing it. 500 */ 501 if (imgp->vmspace_destroyed & 2) 502 p->p_flag &= ~P_INEXEC; 503 if (imgp->vmspace_destroyed) { 504 /* sorry, no more process anymore. exit gracefully */ 505 exit1(W_EXITCODE(0, SIGABRT)); 506 /* NOT REACHED */ 507 return(0); 508 } else { 509 return(error); 510 } 511 } 512 513 /* 514 * execve() system call. 515 */ 516 int 517 sys_execve(struct execve_args *uap) 518 { 519 struct nlookupdata nd; 520 struct image_args args; 521 int error; 522 523 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 524 if (error == 0) { 525 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 526 uap->argv, uap->envv); 527 } 528 if (error == 0) 529 error = kern_execve(&nd, &args); 530 nlookup_done(&nd); 531 exec_free_args(&args); 532 533 /* 534 * The syscall result is returned in registers to the new program. 535 * Linux will register %edx as an atexit function and we must be 536 * sure to set it to 0. XXX 537 */ 538 if (error == 0) 539 uap->sysmsg_result64 = 0; 540 541 return (error); 542 } 543 544 int 545 exec_map_first_page(struct image_params *imgp) 546 { 547 int rv, i; 548 int initial_pagein; 549 vm_page_t ma[VM_INITIAL_PAGEIN]; 550 vm_page_t m; 551 vm_object_t object; 552 553 if (imgp->firstpage) 554 exec_unmap_first_page(imgp); 555 556 /* 557 * The file has to be mappable. 558 */ 559 if ((object = imgp->vp->v_object) == NULL) 560 return (EIO); 561 562 /* 563 * We shouldn't need protection for vm_page_grab() but we certainly 564 * need it for the lookup loop below (lookup/busy race), since 565 * an interrupt can unbusy and free the page before our busy check. 566 */ 567 crit_enter(); 568 m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 569 570 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 571 ma[0] = m; 572 initial_pagein = VM_INITIAL_PAGEIN; 573 if (initial_pagein > object->size) 574 initial_pagein = object->size; 575 for (i = 1; i < initial_pagein; i++) { 576 if ((m = vm_page_lookup(object, i)) != NULL) { 577 if ((m->flags & PG_BUSY) || m->busy) 578 break; 579 if (m->valid) 580 break; 581 vm_page_busy(m); 582 } else { 583 m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 584 if (m == NULL) 585 break; 586 } 587 ma[i] = m; 588 } 589 initial_pagein = i; 590 591 /* 592 * get_pages unbusies all the requested pages except the 593 * primary page (at index 0 in this case). 594 */ 595 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 596 m = vm_page_lookup(object, 0); 597 598 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 599 if (m) { 600 vm_page_protect(m, VM_PROT_NONE); 601 vm_page_free(m); 602 } 603 crit_exit(); 604 return EIO; 605 } 606 } 607 vm_page_hold(m); 608 vm_page_wakeup(m); /* unbusy the page */ 609 crit_exit(); 610 611 imgp->firstpage = sf_buf_alloc(m, SFB_CPUPRIVATE); 612 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 613 614 return 0; 615 } 616 617 void 618 exec_unmap_first_page(struct image_params *imgp) 619 { 620 vm_page_t m; 621 622 crit_enter(); 623 if (imgp->firstpage != NULL) { 624 m = sf_buf_page(imgp->firstpage); 625 sf_buf_free(imgp->firstpage); 626 imgp->firstpage = NULL; 627 imgp->image_header = NULL; 628 vm_page_unhold(m); 629 } 630 crit_exit(); 631 } 632 633 /* 634 * Destroy old address space, and allocate a new stack 635 * The new stack is only SGROWSIZ large because it is grown 636 * automatically in trap.c. 637 * 638 * This is the point of no return. 639 */ 640 int 641 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 642 { 643 struct vmspace *vmspace = imgp->proc->p_vmspace; 644 vm_offset_t stack_addr = USRSTACK - maxssiz; 645 struct proc *p; 646 vm_map_t map; 647 int error; 648 649 /* 650 * Indicate that we cannot gracefully error out any more, kill 651 * any other threads present, and set P_INEXEC to indicate that 652 * we are now messing with the process structure proper. 653 * 654 * If killalllwps() races return an error which coupled with 655 * vmspace_destroyed will cause us to exit. This is what we 656 * want since another thread is patiently waiting for us to exit 657 * in that case. 658 */ 659 p = curproc; 660 imgp->vmspace_destroyed = 1; 661 662 if (curthread->td_proc->p_nthreads > 1) { 663 error = killalllwps(1); 664 if (error) 665 return (error); 666 } 667 imgp->vmspace_destroyed |= 2; /* we are responsible for P_INEXEC */ 668 p->p_flag |= P_INEXEC; 669 670 /* 671 * Prevent a pending AIO from modifying the new address space. 672 */ 673 aio_proc_rundown(imgp->proc); 674 675 /* 676 * Blow away entire process VM, if address space not shared, 677 * otherwise, create a new VM space so that other threads are 678 * not disrupted. If we are execing a resident vmspace we 679 * create a duplicate of it and remap the stack. 680 * 681 * The exitingcnt test is not strictly necessary but has been 682 * included for code sanity (to make the code more deterministic). 683 */ 684 map = &vmspace->vm_map; 685 if (vmcopy) { 686 vmspace_exec(imgp->proc, vmcopy); 687 vmspace = imgp->proc->p_vmspace; 688 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 689 map = &vmspace->vm_map; 690 } else if (vmspace->vm_sysref.refcnt == 1 && 691 vmspace->vm_exitingcnt == 0) { 692 shmexit(vmspace); 693 if (vmspace->vm_upcalls) 694 upc_release(vmspace, ONLY_LWP_IN_PROC(imgp->proc)); 695 pmap_remove_pages(vmspace_pmap(vmspace), 696 0, VM_MAX_USER_ADDRESS); 697 vm_map_remove(map, 0, VM_MAX_USER_ADDRESS); 698 } else { 699 vmspace_exec(imgp->proc, NULL); 700 vmspace = imgp->proc->p_vmspace; 701 map = &vmspace->vm_map; 702 } 703 704 /* Allocate a new stack */ 705 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 706 VM_PROT_ALL, VM_PROT_ALL, 0); 707 if (error) 708 return (error); 709 710 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 711 * VM_STACK case, but they are still used to monitor the size of the 712 * process stack so we can check the stack rlimit. 713 */ 714 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 715 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 716 717 return(0); 718 } 719 720 /* 721 * Copy out argument and environment strings from the old process 722 * address space into the temporary string buffer. 723 */ 724 int 725 exec_copyin_args(struct image_args *args, char *fname, 726 enum exec_path_segflg segflg, char **argv, char **envv) 727 { 728 char *argp, *envp; 729 int error = 0; 730 size_t length; 731 732 bzero(args, sizeof(*args)); 733 734 args->buf = objcache_get(exec_objcache, M_WAITOK); 735 if (args->buf == NULL) 736 return (ENOMEM); 737 args->begin_argv = args->buf; 738 args->endp = args->begin_argv; 739 args->space = ARG_MAX; 740 741 args->fname = args->buf + ARG_MAX; 742 743 /* 744 * Copy the file name. 745 */ 746 if (segflg == PATH_SYSSPACE) { 747 error = copystr(fname, args->fname, PATH_MAX, &length); 748 } else if (segflg == PATH_USERSPACE) { 749 error = copyinstr(fname, args->fname, PATH_MAX, &length); 750 } 751 752 /* 753 * Extract argument strings. argv may not be NULL. The argv 754 * array is terminated by a NULL entry. We special-case the 755 * situation where argv[0] is NULL by passing { filename, NULL } 756 * to the new program to guarentee that the interpreter knows what 757 * file to open in case we exec an interpreted file. Note that 758 * a NULL argv[0] terminates the argv[] array. 759 * 760 * XXX the special-casing of argv[0] is historical and needs to be 761 * revisited. 762 */ 763 if (argv == NULL) 764 error = EFAULT; 765 if (error == 0) { 766 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 767 if (argp == (caddr_t)-1) { 768 error = EFAULT; 769 break; 770 } 771 error = copyinstr(argp, args->endp, 772 args->space, &length); 773 if (error) { 774 if (error == ENAMETOOLONG) 775 error = E2BIG; 776 break; 777 } 778 args->space -= length; 779 args->endp += length; 780 args->argc++; 781 } 782 if (args->argc == 0 && error == 0) { 783 length = strlen(args->fname) + 1; 784 if (length > args->space) { 785 error = E2BIG; 786 } else { 787 bcopy(args->fname, args->endp, length); 788 args->space -= length; 789 args->endp += length; 790 args->argc++; 791 } 792 } 793 } 794 795 args->begin_envv = args->endp; 796 797 /* 798 * extract environment strings. envv may be NULL. 799 */ 800 if (envv && error == 0) { 801 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 802 if (envp == (caddr_t) -1) { 803 error = EFAULT; 804 break; 805 } 806 error = copyinstr(envp, args->endp, args->space, 807 &length); 808 if (error) { 809 if (error == ENAMETOOLONG) 810 error = E2BIG; 811 break; 812 } 813 args->space -= length; 814 args->endp += length; 815 args->envc++; 816 } 817 } 818 return (error); 819 } 820 821 void 822 exec_free_args(struct image_args *args) 823 { 824 if (args->buf) { 825 objcache_put(exec_objcache, args->buf); 826 args->buf = NULL; 827 } 828 } 829 830 /* 831 * Copy strings out to the new process address space, constructing 832 * new arg and env vector tables. Return a pointer to the base 833 * so that it can be used as the initial stack pointer. 834 */ 835 register_t * 836 exec_copyout_strings(struct image_params *imgp) 837 { 838 int argc, envc, sgap; 839 char **vectp; 840 char *stringp, *destp; 841 register_t *stack_base; 842 struct ps_strings *arginfo; 843 int szsigcode; 844 845 /* 846 * Calculate string base and vector table pointers. 847 * Also deal with signal trampoline code for this exec type. 848 */ 849 arginfo = (struct ps_strings *)PS_STRINGS; 850 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 851 if (stackgap_random != 0) 852 sgap = ALIGN(karc4random() & (stackgap_random - 1)); 853 else 854 sgap = 0; 855 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 856 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 857 858 /* 859 * install sigcode 860 */ 861 if (szsigcode) 862 copyout(imgp->proc->p_sysent->sv_sigcode, 863 ((caddr_t)arginfo - szsigcode), szsigcode); 864 865 /* 866 * If we have a valid auxargs ptr, prepare some room 867 * on the stack. 868 * 869 * The '+ 2' is for the null pointers at the end of each of the 870 * arg and env vector sets, and 'AT_COUNT*2' is room for the 871 * ELF Auxargs data. 872 */ 873 if (imgp->auxargs) { 874 vectp = (char **)(destp - (imgp->args->argc + 875 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 876 } else { 877 vectp = (char **)(destp - (imgp->args->argc + 878 imgp->args->envc + 2) * sizeof(char*)); 879 } 880 881 /* 882 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 883 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 884 */ 885 886 /* 887 * vectp also becomes our initial stack base 888 */ 889 stack_base = (register_t *)vectp; 890 891 stringp = imgp->args->begin_argv; 892 argc = imgp->args->argc; 893 envc = imgp->args->envc; 894 895 /* 896 * Copy out strings - arguments and environment. 897 */ 898 copyout(stringp, destp, ARG_MAX - imgp->args->space); 899 900 /* 901 * Fill in "ps_strings" struct for ps, w, etc. 902 */ 903 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 904 suword(&arginfo->ps_nargvstr, argc); 905 906 /* 907 * Fill in argument portion of vector table. 908 */ 909 for (; argc > 0; --argc) { 910 suword(vectp++, (long)(intptr_t)destp); 911 while (*stringp++ != 0) 912 destp++; 913 destp++; 914 } 915 916 /* a null vector table pointer separates the argp's from the envp's */ 917 suword(vectp++, 0); 918 919 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 920 suword(&arginfo->ps_nenvstr, envc); 921 922 /* 923 * Fill in environment portion of vector table. 924 */ 925 for (; envc > 0; --envc) { 926 suword(vectp++, (long)(intptr_t)destp); 927 while (*stringp++ != 0) 928 destp++; 929 destp++; 930 } 931 932 /* end of vector table is a null pointer */ 933 suword(vectp, 0); 934 935 return (stack_base); 936 } 937 938 /* 939 * Check permissions of file to execute. 940 * Return 0 for success or error code on failure. 941 */ 942 int 943 exec_check_permissions(struct image_params *imgp) 944 { 945 struct proc *p = imgp->proc; 946 struct vnode *vp = imgp->vp; 947 struct vattr *attr = imgp->attr; 948 int error; 949 950 /* Get file attributes */ 951 error = VOP_GETATTR(vp, attr); 952 if (error) 953 return (error); 954 955 /* 956 * 1) Check if file execution is disabled for the filesystem that this 957 * file resides on. 958 * 2) Insure that at least one execute bit is on - otherwise root 959 * will always succeed, and we don't want to happen unless the 960 * file really is executable. 961 * 3) Insure that the file is a regular file. 962 */ 963 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 964 ((attr->va_mode & 0111) == 0) || 965 (attr->va_type != VREG)) { 966 return (EACCES); 967 } 968 969 /* 970 * Zero length files can't be exec'd 971 */ 972 if (attr->va_size == 0) 973 return (ENOEXEC); 974 975 /* 976 * Check for execute permission to file based on current credentials. 977 */ 978 error = VOP_ACCESS(vp, VEXEC, p->p_ucred); 979 if (error) 980 return (error); 981 982 /* 983 * Check number of open-for-writes on the file and deny execution 984 * if there are any. 985 */ 986 if (vp->v_writecount) 987 return (ETXTBSY); 988 989 /* 990 * Call filesystem specific open routine, which allows us to read, 991 * write, and mmap the file. Without the VOP_OPEN we can only 992 * stat the file. 993 */ 994 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 995 if (error) 996 return (error); 997 998 return (0); 999 } 1000 1001 /* 1002 * Exec handler registration 1003 */ 1004 int 1005 exec_register(const struct execsw *execsw_arg) 1006 { 1007 const struct execsw **es, **xs, **newexecsw; 1008 int count = 2; /* New slot and trailing NULL */ 1009 1010 if (execsw) 1011 for (es = execsw; *es; es++) 1012 count++; 1013 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1014 if (newexecsw == NULL) 1015 return ENOMEM; 1016 xs = newexecsw; 1017 if (execsw) 1018 for (es = execsw; *es; es++) 1019 *xs++ = *es; 1020 *xs++ = execsw_arg; 1021 *xs = NULL; 1022 if (execsw) 1023 kfree(execsw, M_TEMP); 1024 execsw = newexecsw; 1025 return 0; 1026 } 1027 1028 int 1029 exec_unregister(const struct execsw *execsw_arg) 1030 { 1031 const struct execsw **es, **xs, **newexecsw; 1032 int count = 1; 1033 1034 if (execsw == NULL) 1035 panic("unregister with no handlers left?"); 1036 1037 for (es = execsw; *es; es++) { 1038 if (*es == execsw_arg) 1039 break; 1040 } 1041 if (*es == NULL) 1042 return ENOENT; 1043 for (es = execsw; *es; es++) 1044 if (*es != execsw_arg) 1045 count++; 1046 newexecsw = kmalloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1047 if (newexecsw == NULL) 1048 return ENOMEM; 1049 xs = newexecsw; 1050 for (es = execsw; *es; es++) 1051 if (*es != execsw_arg) 1052 *xs++ = *es; 1053 *xs = NULL; 1054 if (execsw) 1055 kfree(execsw, M_TEMP); 1056 execsw = newexecsw; 1057 return 0; 1058 } 1059