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 1.35 2005/10/09 20:12:34 corecode 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/signalvar.h> 46 #include <sys/pioctl.h> 47 #include <sys/nlookup.h> 48 #include <sys/sfbuf.h> 49 #include <sys/sysent.h> 50 #include <sys/shm.h> 51 #include <sys/sysctl.h> 52 #include <sys/vnode.h> 53 #include <sys/vmmeter.h> 54 #include <sys/aio.h> 55 #include <sys/libkern.h> 56 57 #include <vm/vm.h> 58 #include <vm/vm_param.h> 59 #include <sys/lock.h> 60 #include <vm/pmap.h> 61 #include <vm/vm_page.h> 62 #include <vm/vm_map.h> 63 #include <vm/vm_kern.h> 64 #include <vm/vm_extern.h> 65 #include <vm/vm_object.h> 66 #include <vm/vm_pager.h> 67 68 #include <sys/user.h> 69 #include <machine/reg.h> 70 71 #include <sys/thread2.h> 72 73 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 74 75 static register_t *exec_copyout_strings (struct image_params *); 76 77 /* XXX This should be vm_size_t. */ 78 static u_long ps_strings = PS_STRINGS; 79 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 80 81 /* XXX This should be vm_size_t. */ 82 static u_long usrstack = USRSTACK; 83 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 84 85 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 86 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 87 &ps_arg_cache_limit, 0, ""); 88 89 int ps_argsopen = 1; 90 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 91 92 void print_execve_args(struct image_args *args); 93 int debug_execve_args = 0; 94 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 95 0, ""); 96 97 /* 98 * stackgap_random specifies if the stackgap should have a random size added 99 * to it. It must be a power of 2. If non-zero, the stack gap will be 100 * calculated as: ALIGN(arc4random() & (stackgap_random - 1)). 101 */ 102 static int stackgap_random = 1024; 103 static int 104 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 105 { 106 int error, new_val; 107 new_val = stackgap_random; 108 error = sysctl_handle_int(oidp, &new_val, 0, req); 109 if (error != 0 || req->newptr == NULL) 110 return (error); 111 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 112 return (EINVAL); 113 stackgap_random = new_val; 114 115 return(0); 116 } 117 118 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 119 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 120 121 void 122 print_execve_args(struct image_args *args) 123 { 124 char *cp; 125 int ndx; 126 127 cp = args->begin_argv; 128 for (ndx = 0; ndx < args->argc; ndx++) { 129 printf("\targv[%d]: %s\n", ndx, cp); 130 while (*cp++ != '\0'); 131 } 132 for (ndx = 0; ndx < args->envc; ndx++) { 133 printf("\tenvv[%d]: %s\n", ndx, cp); 134 while (*cp++ != '\0'); 135 } 136 } 137 138 /* 139 * Each of the items is a pointer to a `const struct execsw', hence the 140 * double pointer here. 141 */ 142 static const struct execsw **execsw; 143 144 int 145 kern_execve(struct nlookupdata *nd, struct image_args *args) 146 { 147 struct thread *td = curthread; 148 struct proc *p = td->td_proc; 149 register_t *stack_base; 150 int error, len, i; 151 struct image_params image_params, *imgp; 152 struct vattr attr; 153 int (*img_first) (struct image_params *); 154 155 if (debug_execve_args) { 156 printf("%s()\n", __func__); 157 print_execve_args(args); 158 } 159 160 KKASSERT(p); 161 imgp = &image_params; 162 163 /* 164 * Lock the process and set the P_INEXEC flag to indicate that 165 * it should be left alone until we're done here. This is 166 * necessary to avoid race conditions - e.g. in ptrace() - 167 * that might allow a local user to illicitly obtain elevated 168 * privileges. 169 */ 170 p->p_flag |= P_INEXEC; 171 172 /* 173 * Initialize part of the common data 174 */ 175 imgp->proc = p; 176 imgp->args = args; 177 imgp->attr = &attr; 178 imgp->entry_addr = 0; 179 imgp->resident = 0; 180 imgp->vmspace_destroyed = 0; 181 imgp->interpreted = 0; 182 imgp->interpreter_name[0] = 0; 183 imgp->auxargs = NULL; 184 imgp->vp = NULL; 185 imgp->firstpage = NULL; 186 imgp->ps_strings = 0; 187 imgp->image_header = NULL; 188 189 interpret: 190 191 /* 192 * Translate the file name to a vnode. Unlock the cache entry to 193 * improve parallelism for programs exec'd in parallel. 194 */ 195 if ((error = nlookup(nd)) != 0) 196 goto exec_fail; 197 error = cache_vget(nd->nl_ncp, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 198 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 199 nd->nl_flags &= ~NLC_NCPISLOCKED; 200 cache_unlock(nd->nl_ncp); 201 if (error) 202 goto exec_fail; 203 204 /* 205 * Check file permissions (also 'opens' file) 206 */ 207 error = exec_check_permissions(imgp); 208 if (error) { 209 VOP_UNLOCK(imgp->vp, 0, td); 210 goto exec_fail_dealloc; 211 } 212 213 error = exec_map_first_page(imgp); 214 VOP_UNLOCK(imgp->vp, 0, td); 215 if (error) 216 goto exec_fail_dealloc; 217 218 if (debug_execve_args && imgp->interpreted) { 219 printf(" target is interpreted -- recursive pass\n"); 220 printf(" interpreter: %s\n", imgp->interpreter_name); 221 print_execve_args(args); 222 } 223 224 /* 225 * If the current process has a special image activator it 226 * wants to try first, call it. For example, emulating shell 227 * scripts differently. 228 */ 229 error = -1; 230 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 231 error = img_first(imgp); 232 233 /* 234 * If the vnode has a registered vmspace, exec the vmspace 235 */ 236 if (error == -1 && imgp->vp->v_resident) { 237 error = exec_resident_imgact(imgp); 238 } 239 240 /* 241 * Loop through the list of image activators, calling each one. 242 * An activator returns -1 if there is no match, 0 on success, 243 * and an error otherwise. 244 */ 245 for (i = 0; error == -1 && execsw[i]; ++i) { 246 if (execsw[i]->ex_imgact == NULL || 247 execsw[i]->ex_imgact == img_first) { 248 continue; 249 } 250 error = (*execsw[i]->ex_imgact)(imgp); 251 } 252 253 if (error) { 254 if (error == -1) 255 error = ENOEXEC; 256 goto exec_fail_dealloc; 257 } 258 259 /* 260 * Special interpreter operation, cleanup and loop up to try to 261 * activate the interpreter. 262 */ 263 if (imgp->interpreted) { 264 exec_unmap_first_page(imgp); 265 nlookup_done(nd); 266 vrele(imgp->vp); 267 imgp->vp = NULL; 268 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 269 NLC_FOLLOW); 270 if (error) 271 goto exec_fail; 272 goto interpret; 273 } 274 275 /* 276 * Copy out strings (args and env) and initialize stack base 277 */ 278 stack_base = exec_copyout_strings(imgp); 279 p->p_vmspace->vm_minsaddr = (char *)stack_base; 280 281 /* 282 * If custom stack fixup routine present for this process 283 * let it do the stack setup. If we are running a resident 284 * image there is no auxinfo or other image activator context 285 * so don't try to add fixups to the stack. 286 * 287 * Else stuff argument count as first item on stack 288 */ 289 if (p->p_sysent->sv_fixup && imgp->resident == 0) 290 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 291 else 292 suword(--stack_base, imgp->args->argc); 293 294 /* 295 * For security and other reasons, the file descriptor table cannot 296 * be shared after an exec. 297 */ 298 if (p->p_fd->fd_refcnt > 1) { 299 struct filedesc *tmp; 300 301 tmp = fdcopy(p); 302 fdfree(p); 303 p->p_fd = tmp; 304 } 305 306 /* 307 * For security and other reasons, signal handlers cannot 308 * be shared after an exec. The new proces gets a copy of the old 309 * handlers. In execsigs(), the new process will have its signals 310 * reset. 311 */ 312 if (p->p_procsig->ps_refcnt > 1) { 313 struct procsig *newprocsig; 314 315 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 316 M_SUBPROC, M_WAITOK); 317 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 318 p->p_procsig->ps_refcnt--; 319 p->p_procsig = newprocsig; 320 p->p_procsig->ps_refcnt = 1; 321 if (p->p_sigacts == &p->p_addr->u_sigacts) 322 panic("shared procsig but private sigacts?"); 323 324 p->p_addr->u_sigacts = *p->p_sigacts; 325 p->p_sigacts = &p->p_addr->u_sigacts; 326 } 327 328 /* Stop profiling */ 329 stopprofclock(p); 330 331 /* close files on exec */ 332 fdcloseexec(p); 333 334 /* reset caught signals */ 335 execsigs(p); 336 337 /* name this process - nameiexec(p, ndp) */ 338 len = min(nd->nl_ncp->nc_nlen, MAXCOMLEN); 339 bcopy(nd->nl_ncp->nc_name, p->p_comm, len); 340 p->p_comm[len] = 0; 341 bcopy(p->p_comm, p->p_lwp.lwp_thread->td_comm, MAXCOMLEN+1); 342 343 /* 344 * mark as execed, wakeup the process that vforked (if any) and tell 345 * it that it now has its own resources back 346 */ 347 p->p_flag |= P_EXEC; 348 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 349 p->p_flag &= ~P_PPWAIT; 350 wakeup((caddr_t)p->p_pptr); 351 } 352 353 /* 354 * Implement image setuid/setgid. 355 * 356 * Don't honor setuid/setgid if the filesystem prohibits it or if 357 * the process is being traced. 358 */ 359 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 360 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 361 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 362 (p->p_flag & P_TRACED) == 0) { 363 /* 364 * Turn off syscall tracing for set-id programs, except for 365 * root. Record any set-id flags first to make sure that 366 * we do not regain any tracing during a possible block. 367 */ 368 setsugid(); 369 if (p->p_tracep && suser(td)) { 370 struct vnode *vtmp; 371 372 if ((vtmp = p->p_tracep) != NULL) { 373 p->p_tracep = NULL; 374 p->p_traceflag = 0; 375 vrele(vtmp); 376 } 377 } 378 /* Close any file descriptors 0..2 that reference procfs */ 379 setugidsafety(p); 380 /* Make sure file descriptors 0..2 are in use. */ 381 error = fdcheckstd(p); 382 if (error != 0) 383 goto exec_fail_dealloc; 384 /* 385 * Set the new credentials. 386 */ 387 cratom(&p->p_ucred); 388 if (attr.va_mode & VSUID) 389 change_euid(attr.va_uid); 390 if (attr.va_mode & VSGID) 391 p->p_ucred->cr_gid = attr.va_gid; 392 393 /* 394 * Clear local varsym variables 395 */ 396 varsymset_clean(&p->p_varsymset); 397 } else { 398 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 399 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 400 p->p_flag &= ~P_SUGID; 401 } 402 403 /* 404 * Implement correct POSIX saved-id behavior. 405 */ 406 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 407 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 408 cratom(&p->p_ucred); 409 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 410 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 411 } 412 413 /* 414 * Store the vp for use in procfs 415 */ 416 if (p->p_textvp) /* release old reference */ 417 vrele(p->p_textvp); 418 p->p_textvp = imgp->vp; 419 vref(p->p_textvp); 420 421 /* 422 * Notify others that we exec'd, and clear the P_INEXEC flag 423 * as we're now a bona fide freshly-execed process. 424 */ 425 KNOTE(&p->p_klist, NOTE_EXEC); 426 p->p_flag &= ~P_INEXEC; 427 428 /* 429 * If tracing the process, trap to debugger so breakpoints 430 * can be set before the program executes. 431 */ 432 STOPEVENT(p, S_EXEC, 0); 433 434 if (p->p_flag & P_TRACED) 435 psignal(p, SIGTRAP); 436 437 /* clear "fork but no exec" flag, as we _are_ execing */ 438 p->p_acflag &= ~AFORK; 439 440 /* Set values passed into the program in registers. */ 441 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 442 imgp->ps_strings); 443 444 /* Free any previous argument cache */ 445 if (p->p_args && --p->p_args->ar_ref == 0) 446 FREE(p->p_args, M_PARGS); 447 p->p_args = NULL; 448 449 /* Cache arguments if they fit inside our allowance */ 450 i = imgp->args->begin_envv - imgp->args->begin_argv; 451 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 452 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 453 M_PARGS, M_WAITOK); 454 p->p_args->ar_ref = 1; 455 p->p_args->ar_length = i; 456 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 457 } 458 459 exec_fail_dealloc: 460 461 /* 462 * free various allocated resources 463 */ 464 if (imgp->firstpage) 465 exec_unmap_first_page(imgp); 466 467 if (imgp->vp) { 468 vrele(imgp->vp); 469 imgp->vp = NULL; 470 } 471 472 if (error == 0) { 473 ++mycpu->gd_cnt.v_exec; 474 return (0); 475 } 476 477 exec_fail: 478 /* we're done here, clear P_INEXEC */ 479 p->p_flag &= ~P_INEXEC; 480 if (imgp->vmspace_destroyed) { 481 /* sorry, no more process anymore. exit gracefully */ 482 exit1(W_EXITCODE(0, SIGABRT)); 483 /* NOT REACHED */ 484 return(0); 485 } else { 486 return(error); 487 } 488 } 489 490 /* 491 * execve() system call. 492 */ 493 int 494 execve(struct execve_args *uap) 495 { 496 struct nlookupdata nd; 497 struct image_args args; 498 int error; 499 500 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 501 if (error == 0) { 502 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 503 uap->argv, uap->envv); 504 } 505 if (error == 0) 506 error = kern_execve(&nd, &args); 507 nlookup_done(&nd); 508 exec_free_args(&args); 509 510 /* 511 * The syscall result is returned in registers to the new program. 512 * Linux will register %edx as an atexit function and we must be 513 * sure to set it to 0. XXX 514 */ 515 if (error == 0) 516 uap->sysmsg_result64 = 0; 517 518 return (error); 519 } 520 521 int 522 exec_map_first_page(struct image_params *imgp) 523 { 524 int rv, i; 525 int initial_pagein; 526 vm_page_t ma[VM_INITIAL_PAGEIN]; 527 vm_page_t m; 528 vm_object_t object; 529 int error; 530 531 if (imgp->firstpage) 532 exec_unmap_first_page(imgp); 533 534 /* 535 * XXX the callers should really use vn_open so we don't have to 536 * do this junk. 537 */ 538 if ((error = VOP_GETVOBJECT(imgp->vp, &object)) != 0) { 539 if (vn_canvmio(imgp->vp) == TRUE) { 540 error = vfs_object_create(imgp->vp, curthread); 541 if (error == 0) 542 error = VOP_GETVOBJECT(imgp->vp, &object); 543 } 544 } 545 if (error) 546 return (EIO); 547 548 /* 549 * We shouldn't need protection for vm_page_grab() but we certainly 550 * need it for the lookup loop below (lookup/busy race), since 551 * an interrupt can unbusy and free the page before our busy check. 552 */ 553 crit_enter(); 554 m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 555 556 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 557 ma[0] = m; 558 initial_pagein = VM_INITIAL_PAGEIN; 559 if (initial_pagein > object->size) 560 initial_pagein = object->size; 561 for (i = 1; i < initial_pagein; i++) { 562 if ((m = vm_page_lookup(object, i)) != NULL) { 563 if ((m->flags & PG_BUSY) || m->busy) 564 break; 565 if (m->valid) 566 break; 567 vm_page_busy(m); 568 } else { 569 m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 570 if (m == NULL) 571 break; 572 } 573 ma[i] = m; 574 } 575 initial_pagein = i; 576 577 /* 578 * get_pages unbusies all the requested pages except the 579 * primary page (at index 0 in this case). 580 */ 581 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 582 m = vm_page_lookup(object, 0); 583 584 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 585 if (m) { 586 vm_page_protect(m, VM_PROT_NONE); 587 vm_page_free(m); 588 } 589 crit_exit(); 590 return EIO; 591 } 592 } 593 vm_page_hold(m); 594 vm_page_wakeup(m); /* unbusy the page */ 595 crit_exit(); 596 597 imgp->firstpage = sf_buf_alloc(m, SFB_CPUPRIVATE); 598 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 599 600 return 0; 601 } 602 603 void 604 exec_unmap_first_page(struct image_params *imgp) 605 { 606 vm_page_t m; 607 608 crit_enter(); 609 if (imgp->firstpage != NULL) { 610 m = sf_buf_page(imgp->firstpage); 611 sf_buf_free(imgp->firstpage); 612 imgp->firstpage = NULL; 613 imgp->image_header = NULL; 614 vm_page_unhold(m); 615 } 616 crit_exit(); 617 } 618 619 /* 620 * Destroy old address space, and allocate a new stack 621 * The new stack is only SGROWSIZ large because it is grown 622 * automatically in trap.c. 623 */ 624 int 625 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 626 { 627 int error; 628 struct vmspace *vmspace = imgp->proc->p_vmspace; 629 vm_offset_t stack_addr = USRSTACK - maxssiz; 630 vm_map_t map; 631 632 imgp->vmspace_destroyed = 1; 633 634 /* 635 * Prevent a pending AIO from modifying the new address space. 636 */ 637 aio_proc_rundown(imgp->proc); 638 639 /* 640 * Blow away entire process VM, if address space not shared, 641 * otherwise, create a new VM space so that other threads are 642 * not disrupted. If we are execing a resident vmspace we 643 * create a duplicate of it and remap the stack. 644 * 645 * The exitingcnt test is not strictly necessary but has been 646 * included for code sanity (to make the code more deterministic). 647 */ 648 map = &vmspace->vm_map; 649 if (vmcopy) { 650 vmspace_exec(imgp->proc, vmcopy); 651 vmspace = imgp->proc->p_vmspace; 652 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 653 map = &vmspace->vm_map; 654 } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { 655 shmexit(vmspace); 656 if (vmspace->vm_upcalls) 657 upc_release(vmspace, &imgp->proc->p_lwp); 658 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 659 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 660 } else { 661 vmspace_exec(imgp->proc, NULL); 662 vmspace = imgp->proc->p_vmspace; 663 map = &vmspace->vm_map; 664 } 665 666 /* Allocate a new stack */ 667 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 668 VM_PROT_ALL, VM_PROT_ALL, 0); 669 if (error) 670 return (error); 671 672 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 673 * VM_STACK case, but they are still used to monitor the size of the 674 * process stack so we can check the stack rlimit. 675 */ 676 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 677 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 678 679 return(0); 680 } 681 682 /* 683 * Copy out argument and environment strings from the old process 684 * address space into the temporary string buffer. 685 */ 686 int 687 exec_copyin_args(struct image_args *args, char *fname, 688 enum exec_path_segflg segflg, char **argv, char **envv) 689 { 690 char *argp, *envp; 691 int error = 0; 692 size_t length; 693 694 bzero(args, sizeof(*args)); 695 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 696 if (args->buf == NULL) 697 return (ENOMEM); 698 args->begin_argv = args->buf; 699 args->endp = args->begin_argv; 700 args->space = ARG_MAX; 701 702 args->fname = args->buf + ARG_MAX; 703 704 /* 705 * Copy the file name. 706 */ 707 if (segflg == PATH_SYSSPACE) { 708 error = copystr(fname, args->fname, PATH_MAX, &length); 709 } else if (segflg == PATH_USERSPACE) { 710 error = copyinstr(fname, args->fname, PATH_MAX, &length); 711 } 712 713 /* 714 * Extract argument strings. argv may not be NULL. The argv 715 * array is terminated by a NULL entry. We special-case the 716 * situation where argv[0] is NULL by passing { filename, NULL } 717 * to the new program to guarentee that the interpreter knows what 718 * file to open in case we exec an interpreted file. Note that 719 * a NULL argv[0] terminates the argv[] array. 720 * 721 * XXX the special-casing of argv[0] is historical and needs to be 722 * revisited. 723 */ 724 if (argv == NULL) 725 error = EFAULT; 726 if (error == 0) { 727 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 728 if (argp == (caddr_t)-1) { 729 error = EFAULT; 730 break; 731 } 732 error = copyinstr(argp, args->endp, 733 args->space, &length); 734 if (error) { 735 if (error == ENAMETOOLONG) 736 error = E2BIG; 737 break; 738 } 739 args->space -= length; 740 args->endp += length; 741 args->argc++; 742 } 743 if (args->argc == 0 && error == 0) { 744 length = strlen(args->fname) + 1; 745 if (length > args->space) { 746 error = E2BIG; 747 } else { 748 bcopy(args->fname, args->endp, length); 749 args->space -= length; 750 args->endp += length; 751 args->argc++; 752 } 753 } 754 } 755 756 args->begin_envv = args->endp; 757 758 /* 759 * extract environment strings. envv may be NULL. 760 */ 761 if (envv && error == 0) { 762 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 763 if (envp == (caddr_t) -1) { 764 error = EFAULT; 765 break; 766 } 767 error = copyinstr(envp, args->endp, args->space, 768 &length); 769 if (error) { 770 if (error == ENAMETOOLONG) 771 error = E2BIG; 772 break; 773 } 774 args->space -= length; 775 args->endp += length; 776 args->envc++; 777 } 778 } 779 return (error); 780 } 781 782 void 783 exec_free_args(struct image_args *args) 784 { 785 if (args->buf) { 786 kmem_free_wakeup(exec_map, 787 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 788 args->buf = NULL; 789 } 790 } 791 792 /* 793 * Copy strings out to the new process address space, constructing 794 * new arg and env vector tables. Return a pointer to the base 795 * so that it can be used as the initial stack pointer. 796 */ 797 register_t * 798 exec_copyout_strings(struct image_params *imgp) 799 { 800 int argc, envc, sgap; 801 char **vectp; 802 char *stringp, *destp; 803 register_t *stack_base; 804 struct ps_strings *arginfo; 805 int szsigcode; 806 807 /* 808 * Calculate string base and vector table pointers. 809 * Also deal with signal trampoline code for this exec type. 810 */ 811 arginfo = (struct ps_strings *)PS_STRINGS; 812 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 813 if (stackgap_random != 0) 814 sgap = ALIGN(arc4random() & (stackgap_random - 1)); 815 else 816 sgap = 0; 817 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 818 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 819 820 /* 821 * install sigcode 822 */ 823 if (szsigcode) 824 copyout(imgp->proc->p_sysent->sv_sigcode, 825 ((caddr_t)arginfo - szsigcode), szsigcode); 826 827 /* 828 * If we have a valid auxargs ptr, prepare some room 829 * on the stack. 830 * 831 * The '+ 2' is for the null pointers at the end of each of the 832 * arg and env vector sets, and 'AT_COUNT*2' is room for the 833 * ELF Auxargs data. 834 */ 835 if (imgp->auxargs) { 836 vectp = (char **)(destp - (imgp->args->argc + 837 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 838 } else { 839 vectp = (char **)(destp - (imgp->args->argc + 840 imgp->args->envc + 2) * sizeof(char*)); 841 } 842 843 /* 844 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 845 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 846 */ 847 848 /* 849 * vectp also becomes our initial stack base 850 */ 851 stack_base = (register_t *)vectp; 852 853 stringp = imgp->args->begin_argv; 854 argc = imgp->args->argc; 855 envc = imgp->args->envc; 856 857 /* 858 * Copy out strings - arguments and environment. 859 */ 860 copyout(stringp, destp, ARG_MAX - imgp->args->space); 861 862 /* 863 * Fill in "ps_strings" struct for ps, w, etc. 864 */ 865 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 866 suword(&arginfo->ps_nargvstr, argc); 867 868 /* 869 * Fill in argument portion of vector table. 870 */ 871 for (; argc > 0; --argc) { 872 suword(vectp++, (long)(intptr_t)destp); 873 while (*stringp++ != 0) 874 destp++; 875 destp++; 876 } 877 878 /* a null vector table pointer separates the argp's from the envp's */ 879 suword(vectp++, 0); 880 881 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 882 suword(&arginfo->ps_nenvstr, envc); 883 884 /* 885 * Fill in environment portion of vector table. 886 */ 887 for (; envc > 0; --envc) { 888 suword(vectp++, (long)(intptr_t)destp); 889 while (*stringp++ != 0) 890 destp++; 891 destp++; 892 } 893 894 /* end of vector table is a null pointer */ 895 suword(vectp, 0); 896 897 return (stack_base); 898 } 899 900 /* 901 * Check permissions of file to execute. 902 * Return 0 for success or error code on failure. 903 */ 904 int 905 exec_check_permissions(struct image_params *imgp) 906 { 907 struct proc *p = imgp->proc; 908 struct vnode *vp = imgp->vp; 909 struct vattr *attr = imgp->attr; 910 struct thread *td = p->p_thread; 911 int error; 912 913 /* Get file attributes */ 914 error = VOP_GETATTR(vp, attr, td); 915 if (error) 916 return (error); 917 918 /* 919 * 1) Check if file execution is disabled for the filesystem that this 920 * file resides on. 921 * 2) Insure that at least one execute bit is on - otherwise root 922 * will always succeed, and we don't want to happen unless the 923 * file really is executable. 924 * 3) Insure that the file is a regular file. 925 */ 926 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 927 ((attr->va_mode & 0111) == 0) || 928 (attr->va_type != VREG)) { 929 return (EACCES); 930 } 931 932 /* 933 * Zero length files can't be exec'd 934 */ 935 if (attr->va_size == 0) 936 return (ENOEXEC); 937 938 /* 939 * Check for execute permission to file based on current credentials. 940 */ 941 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 942 if (error) 943 return (error); 944 945 /* 946 * Check number of open-for-writes on the file and deny execution 947 * if there are any. 948 */ 949 if (vp->v_writecount) 950 return (ETXTBSY); 951 952 /* 953 * Call filesystem specific open routine (which does nothing in the 954 * general case). 955 */ 956 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL, td); 957 if (error) 958 return (error); 959 960 return (0); 961 } 962 963 /* 964 * Exec handler registration 965 */ 966 int 967 exec_register(const struct execsw *execsw_arg) 968 { 969 const struct execsw **es, **xs, **newexecsw; 970 int count = 2; /* New slot and trailing NULL */ 971 972 if (execsw) 973 for (es = execsw; *es; es++) 974 count++; 975 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 976 if (newexecsw == NULL) 977 return ENOMEM; 978 xs = newexecsw; 979 if (execsw) 980 for (es = execsw; *es; es++) 981 *xs++ = *es; 982 *xs++ = execsw_arg; 983 *xs = NULL; 984 if (execsw) 985 free(execsw, M_TEMP); 986 execsw = newexecsw; 987 return 0; 988 } 989 990 int 991 exec_unregister(const struct execsw *execsw_arg) 992 { 993 const struct execsw **es, **xs, **newexecsw; 994 int count = 1; 995 996 if (execsw == NULL) 997 panic("unregister with no handlers left?"); 998 999 for (es = execsw; *es; es++) { 1000 if (*es == execsw_arg) 1001 break; 1002 } 1003 if (*es == NULL) 1004 return ENOENT; 1005 for (es = execsw; *es; es++) 1006 if (*es != execsw_arg) 1007 count++; 1008 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1009 if (newexecsw == NULL) 1010 return ENOMEM; 1011 xs = newexecsw; 1012 for (es = execsw; *es; es++) 1013 if (*es != execsw_arg) 1014 *xs++ = *es; 1015 *xs = NULL; 1016 if (execsw) 1017 free(execsw, M_TEMP); 1018 execsw = newexecsw; 1019 return 0; 1020 } 1021