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 1.36 2006/03/29 18:44:50 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/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; 529 530 if (imgp->firstpage) 531 exec_unmap_first_page(imgp); 532 533 /* 534 * The file has to be mappable. 535 */ 536 if ((object = imgp->vp->v_object) == NULL) 537 return (EIO); 538 539 /* 540 * We shouldn't need protection for vm_page_grab() but we certainly 541 * need it for the lookup loop below (lookup/busy race), since 542 * an interrupt can unbusy and free the page before our busy check. 543 */ 544 crit_enter(); 545 m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 546 547 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 548 ma[0] = m; 549 initial_pagein = VM_INITIAL_PAGEIN; 550 if (initial_pagein > object->size) 551 initial_pagein = object->size; 552 for (i = 1; i < initial_pagein; i++) { 553 if ((m = vm_page_lookup(object, i)) != NULL) { 554 if ((m->flags & PG_BUSY) || m->busy) 555 break; 556 if (m->valid) 557 break; 558 vm_page_busy(m); 559 } else { 560 m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 561 if (m == NULL) 562 break; 563 } 564 ma[i] = m; 565 } 566 initial_pagein = i; 567 568 /* 569 * get_pages unbusies all the requested pages except the 570 * primary page (at index 0 in this case). 571 */ 572 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 573 m = vm_page_lookup(object, 0); 574 575 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 576 if (m) { 577 vm_page_protect(m, VM_PROT_NONE); 578 vm_page_free(m); 579 } 580 crit_exit(); 581 return EIO; 582 } 583 } 584 vm_page_hold(m); 585 vm_page_wakeup(m); /* unbusy the page */ 586 crit_exit(); 587 588 imgp->firstpage = sf_buf_alloc(m, SFB_CPUPRIVATE); 589 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 590 591 return 0; 592 } 593 594 void 595 exec_unmap_first_page(struct image_params *imgp) 596 { 597 vm_page_t m; 598 599 crit_enter(); 600 if (imgp->firstpage != NULL) { 601 m = sf_buf_page(imgp->firstpage); 602 sf_buf_free(imgp->firstpage); 603 imgp->firstpage = NULL; 604 imgp->image_header = NULL; 605 vm_page_unhold(m); 606 } 607 crit_exit(); 608 } 609 610 /* 611 * Destroy old address space, and allocate a new stack 612 * The new stack is only SGROWSIZ large because it is grown 613 * automatically in trap.c. 614 */ 615 int 616 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 617 { 618 int error; 619 struct vmspace *vmspace = imgp->proc->p_vmspace; 620 vm_offset_t stack_addr = USRSTACK - maxssiz; 621 vm_map_t map; 622 623 imgp->vmspace_destroyed = 1; 624 625 /* 626 * Prevent a pending AIO from modifying the new address space. 627 */ 628 aio_proc_rundown(imgp->proc); 629 630 /* 631 * Blow away entire process VM, if address space not shared, 632 * otherwise, create a new VM space so that other threads are 633 * not disrupted. If we are execing a resident vmspace we 634 * create a duplicate of it and remap the stack. 635 * 636 * The exitingcnt test is not strictly necessary but has been 637 * included for code sanity (to make the code more deterministic). 638 */ 639 map = &vmspace->vm_map; 640 if (vmcopy) { 641 vmspace_exec(imgp->proc, vmcopy); 642 vmspace = imgp->proc->p_vmspace; 643 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 644 map = &vmspace->vm_map; 645 } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { 646 shmexit(vmspace); 647 if (vmspace->vm_upcalls) 648 upc_release(vmspace, &imgp->proc->p_lwp); 649 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 650 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 651 } else { 652 vmspace_exec(imgp->proc, NULL); 653 vmspace = imgp->proc->p_vmspace; 654 map = &vmspace->vm_map; 655 } 656 657 /* Allocate a new stack */ 658 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 659 VM_PROT_ALL, VM_PROT_ALL, 0); 660 if (error) 661 return (error); 662 663 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 664 * VM_STACK case, but they are still used to monitor the size of the 665 * process stack so we can check the stack rlimit. 666 */ 667 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 668 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 669 670 return(0); 671 } 672 673 /* 674 * Copy out argument and environment strings from the old process 675 * address space into the temporary string buffer. 676 */ 677 int 678 exec_copyin_args(struct image_args *args, char *fname, 679 enum exec_path_segflg segflg, char **argv, char **envv) 680 { 681 char *argp, *envp; 682 int error = 0; 683 size_t length; 684 685 bzero(args, sizeof(*args)); 686 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 687 if (args->buf == NULL) 688 return (ENOMEM); 689 args->begin_argv = args->buf; 690 args->endp = args->begin_argv; 691 args->space = ARG_MAX; 692 693 args->fname = args->buf + ARG_MAX; 694 695 /* 696 * Copy the file name. 697 */ 698 if (segflg == PATH_SYSSPACE) { 699 error = copystr(fname, args->fname, PATH_MAX, &length); 700 } else if (segflg == PATH_USERSPACE) { 701 error = copyinstr(fname, args->fname, PATH_MAX, &length); 702 } 703 704 /* 705 * Extract argument strings. argv may not be NULL. The argv 706 * array is terminated by a NULL entry. We special-case the 707 * situation where argv[0] is NULL by passing { filename, NULL } 708 * to the new program to guarentee that the interpreter knows what 709 * file to open in case we exec an interpreted file. Note that 710 * a NULL argv[0] terminates the argv[] array. 711 * 712 * XXX the special-casing of argv[0] is historical and needs to be 713 * revisited. 714 */ 715 if (argv == NULL) 716 error = EFAULT; 717 if (error == 0) { 718 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 719 if (argp == (caddr_t)-1) { 720 error = EFAULT; 721 break; 722 } 723 error = copyinstr(argp, args->endp, 724 args->space, &length); 725 if (error) { 726 if (error == ENAMETOOLONG) 727 error = E2BIG; 728 break; 729 } 730 args->space -= length; 731 args->endp += length; 732 args->argc++; 733 } 734 if (args->argc == 0 && error == 0) { 735 length = strlen(args->fname) + 1; 736 if (length > args->space) { 737 error = E2BIG; 738 } else { 739 bcopy(args->fname, args->endp, length); 740 args->space -= length; 741 args->endp += length; 742 args->argc++; 743 } 744 } 745 } 746 747 args->begin_envv = args->endp; 748 749 /* 750 * extract environment strings. envv may be NULL. 751 */ 752 if (envv && error == 0) { 753 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 754 if (envp == (caddr_t) -1) { 755 error = EFAULT; 756 break; 757 } 758 error = copyinstr(envp, args->endp, args->space, 759 &length); 760 if (error) { 761 if (error == ENAMETOOLONG) 762 error = E2BIG; 763 break; 764 } 765 args->space -= length; 766 args->endp += length; 767 args->envc++; 768 } 769 } 770 return (error); 771 } 772 773 void 774 exec_free_args(struct image_args *args) 775 { 776 if (args->buf) { 777 kmem_free_wakeup(exec_map, 778 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 779 args->buf = NULL; 780 } 781 } 782 783 /* 784 * Copy strings out to the new process address space, constructing 785 * new arg and env vector tables. Return a pointer to the base 786 * so that it can be used as the initial stack pointer. 787 */ 788 register_t * 789 exec_copyout_strings(struct image_params *imgp) 790 { 791 int argc, envc, sgap; 792 char **vectp; 793 char *stringp, *destp; 794 register_t *stack_base; 795 struct ps_strings *arginfo; 796 int szsigcode; 797 798 /* 799 * Calculate string base and vector table pointers. 800 * Also deal with signal trampoline code for this exec type. 801 */ 802 arginfo = (struct ps_strings *)PS_STRINGS; 803 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 804 if (stackgap_random != 0) 805 sgap = ALIGN(arc4random() & (stackgap_random - 1)); 806 else 807 sgap = 0; 808 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 809 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 810 811 /* 812 * install sigcode 813 */ 814 if (szsigcode) 815 copyout(imgp->proc->p_sysent->sv_sigcode, 816 ((caddr_t)arginfo - szsigcode), szsigcode); 817 818 /* 819 * If we have a valid auxargs ptr, prepare some room 820 * on the stack. 821 * 822 * The '+ 2' is for the null pointers at the end of each of the 823 * arg and env vector sets, and 'AT_COUNT*2' is room for the 824 * ELF Auxargs data. 825 */ 826 if (imgp->auxargs) { 827 vectp = (char **)(destp - (imgp->args->argc + 828 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 829 } else { 830 vectp = (char **)(destp - (imgp->args->argc + 831 imgp->args->envc + 2) * sizeof(char*)); 832 } 833 834 /* 835 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 836 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 837 */ 838 839 /* 840 * vectp also becomes our initial stack base 841 */ 842 stack_base = (register_t *)vectp; 843 844 stringp = imgp->args->begin_argv; 845 argc = imgp->args->argc; 846 envc = imgp->args->envc; 847 848 /* 849 * Copy out strings - arguments and environment. 850 */ 851 copyout(stringp, destp, ARG_MAX - imgp->args->space); 852 853 /* 854 * Fill in "ps_strings" struct for ps, w, etc. 855 */ 856 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 857 suword(&arginfo->ps_nargvstr, argc); 858 859 /* 860 * Fill in argument portion of vector table. 861 */ 862 for (; argc > 0; --argc) { 863 suword(vectp++, (long)(intptr_t)destp); 864 while (*stringp++ != 0) 865 destp++; 866 destp++; 867 } 868 869 /* a null vector table pointer separates the argp's from the envp's */ 870 suword(vectp++, 0); 871 872 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 873 suword(&arginfo->ps_nenvstr, envc); 874 875 /* 876 * Fill in environment portion of vector table. 877 */ 878 for (; envc > 0; --envc) { 879 suword(vectp++, (long)(intptr_t)destp); 880 while (*stringp++ != 0) 881 destp++; 882 destp++; 883 } 884 885 /* end of vector table is a null pointer */ 886 suword(vectp, 0); 887 888 return (stack_base); 889 } 890 891 /* 892 * Check permissions of file to execute. 893 * Return 0 for success or error code on failure. 894 */ 895 int 896 exec_check_permissions(struct image_params *imgp) 897 { 898 struct proc *p = imgp->proc; 899 struct vnode *vp = imgp->vp; 900 struct vattr *attr = imgp->attr; 901 struct thread *td = p->p_thread; 902 int error; 903 904 /* Get file attributes */ 905 error = VOP_GETATTR(vp, attr, td); 906 if (error) 907 return (error); 908 909 /* 910 * 1) Check if file execution is disabled for the filesystem that this 911 * file resides on. 912 * 2) Insure that at least one execute bit is on - otherwise root 913 * will always succeed, and we don't want to happen unless the 914 * file really is executable. 915 * 3) Insure that the file is a regular file. 916 */ 917 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 918 ((attr->va_mode & 0111) == 0) || 919 (attr->va_type != VREG)) { 920 return (EACCES); 921 } 922 923 /* 924 * Zero length files can't be exec'd 925 */ 926 if (attr->va_size == 0) 927 return (ENOEXEC); 928 929 /* 930 * Check for execute permission to file based on current credentials. 931 */ 932 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); 933 if (error) 934 return (error); 935 936 /* 937 * Check number of open-for-writes on the file and deny execution 938 * if there are any. 939 */ 940 if (vp->v_writecount) 941 return (ETXTBSY); 942 943 /* 944 * Call filesystem specific open routine, which allows us to read, 945 * write, and mmap the file. Without the VOP_OPEN we can only 946 * stat the file. 947 */ 948 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL, td); 949 if (error) 950 return (error); 951 952 return (0); 953 } 954 955 /* 956 * Exec handler registration 957 */ 958 int 959 exec_register(const struct execsw *execsw_arg) 960 { 961 const struct execsw **es, **xs, **newexecsw; 962 int count = 2; /* New slot and trailing NULL */ 963 964 if (execsw) 965 for (es = execsw; *es; es++) 966 count++; 967 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 968 if (newexecsw == NULL) 969 return ENOMEM; 970 xs = newexecsw; 971 if (execsw) 972 for (es = execsw; *es; es++) 973 *xs++ = *es; 974 *xs++ = execsw_arg; 975 *xs = NULL; 976 if (execsw) 977 free(execsw, M_TEMP); 978 execsw = newexecsw; 979 return 0; 980 } 981 982 int 983 exec_unregister(const struct execsw *execsw_arg) 984 { 985 const struct execsw **es, **xs, **newexecsw; 986 int count = 1; 987 988 if (execsw == NULL) 989 panic("unregister with no handlers left?"); 990 991 for (es = execsw; *es; es++) { 992 if (*es == execsw_arg) 993 break; 994 } 995 if (*es == NULL) 996 return ENOENT; 997 for (es = execsw; *es; es++) 998 if (*es != execsw_arg) 999 count++; 1000 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1001 if (newexecsw == NULL) 1002 return ENOMEM; 1003 xs = newexecsw; 1004 for (es = execsw; *es; es++) 1005 if (*es != execsw_arg) 1006 *xs++ = *es; 1007 *xs = NULL; 1008 if (execsw) 1009 free(execsw, M_TEMP); 1010 execsw = newexecsw; 1011 return 0; 1012 } 1013