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 1.40 2006/06/05 07:26:10 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 <machine/reg.h> 71 72 #include <sys/thread2.h> 73 74 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 75 76 static register_t *exec_copyout_strings (struct image_params *); 77 78 /* XXX This should be vm_size_t. */ 79 static u_long ps_strings = PS_STRINGS; 80 SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); 81 82 /* XXX This should be vm_size_t. */ 83 static u_long usrstack = USRSTACK; 84 SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); 85 86 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 87 SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 88 &ps_arg_cache_limit, 0, ""); 89 90 int ps_argsopen = 1; 91 SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); 92 93 void print_execve_args(struct image_args *args); 94 int debug_execve_args = 0; 95 SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 96 0, ""); 97 98 /* 99 * stackgap_random specifies if the stackgap should have a random size added 100 * to it. It must be a power of 2. If non-zero, the stack gap will be 101 * calculated as: ALIGN(arc4random() & (stackgap_random - 1)). 102 */ 103 static int stackgap_random = 1024; 104 static int 105 sysctl_kern_stackgap(SYSCTL_HANDLER_ARGS) 106 { 107 int error, new_val; 108 new_val = stackgap_random; 109 error = sysctl_handle_int(oidp, &new_val, 0, req); 110 if (error != 0 || req->newptr == NULL) 111 return (error); 112 if ((new_val < 0) || (new_val > 16 * PAGE_SIZE) || ! powerof2(new_val)) 113 return (EINVAL); 114 stackgap_random = new_val; 115 116 return(0); 117 } 118 119 SYSCTL_PROC(_kern, OID_AUTO, stackgap_random, CTLFLAG_RW|CTLTYPE_UINT, 120 0, 0, sysctl_kern_stackgap, "IU", "Max random stack gap (power of 2)"); 121 122 void 123 print_execve_args(struct image_args *args) 124 { 125 char *cp; 126 int ndx; 127 128 cp = args->begin_argv; 129 for (ndx = 0; ndx < args->argc; ndx++) { 130 printf("\targv[%d]: %s\n", ndx, cp); 131 while (*cp++ != '\0'); 132 } 133 for (ndx = 0; ndx < args->envc; ndx++) { 134 printf("\tenvv[%d]: %s\n", ndx, cp); 135 while (*cp++ != '\0'); 136 } 137 } 138 139 /* 140 * Each of the items is a pointer to a `const struct execsw', hence the 141 * double pointer here. 142 */ 143 static const struct execsw **execsw; 144 145 int 146 kern_execve(struct nlookupdata *nd, struct image_args *args) 147 { 148 struct thread *td = curthread; 149 struct proc *p = td->td_proc; 150 register_t *stack_base; 151 int error, len, i; 152 struct image_params image_params, *imgp; 153 struct vattr attr; 154 int (*img_first) (struct image_params *); 155 156 if (debug_execve_args) { 157 printf("%s()\n", __func__); 158 print_execve_args(args); 159 } 160 161 KKASSERT(p); 162 imgp = &image_params; 163 164 /* 165 * Lock the process and set the P_INEXEC flag to indicate that 166 * it should be left alone until we're done here. This is 167 * necessary to avoid race conditions - e.g. in ptrace() - 168 * that might allow a local user to illicitly obtain elevated 169 * privileges. 170 */ 171 p->p_flag |= P_INEXEC; 172 173 /* 174 * Initialize part of the common data 175 */ 176 imgp->proc = p; 177 imgp->args = args; 178 imgp->attr = &attr; 179 imgp->entry_addr = 0; 180 imgp->resident = 0; 181 imgp->vmspace_destroyed = 0; 182 imgp->interpreted = 0; 183 imgp->interpreter_name[0] = 0; 184 imgp->auxargs = NULL; 185 imgp->vp = NULL; 186 imgp->firstpage = NULL; 187 imgp->ps_strings = 0; 188 imgp->image_header = NULL; 189 190 interpret: 191 192 /* 193 * Translate the file name to a vnode. Unlock the cache entry to 194 * improve parallelism for programs exec'd in parallel. 195 */ 196 if ((error = nlookup(nd)) != 0) 197 goto exec_fail; 198 error = cache_vget(nd->nl_ncp, nd->nl_cred, LK_EXCLUSIVE, &imgp->vp); 199 KKASSERT(nd->nl_flags & NLC_NCPISLOCKED); 200 nd->nl_flags &= ~NLC_NCPISLOCKED; 201 cache_unlock(nd->nl_ncp); 202 if (error) 203 goto exec_fail; 204 205 /* 206 * Check file permissions (also 'opens' file) 207 */ 208 error = exec_check_permissions(imgp); 209 if (error) { 210 VOP_UNLOCK(imgp->vp, 0); 211 goto exec_fail_dealloc; 212 } 213 214 error = exec_map_first_page(imgp); 215 VOP_UNLOCK(imgp->vp, 0); 216 if (error) 217 goto exec_fail_dealloc; 218 219 if (debug_execve_args && imgp->interpreted) { 220 printf(" target is interpreted -- recursive pass\n"); 221 printf(" interpreter: %s\n", imgp->interpreter_name); 222 print_execve_args(args); 223 } 224 225 /* 226 * If the current process has a special image activator it 227 * wants to try first, call it. For example, emulating shell 228 * scripts differently. 229 */ 230 error = -1; 231 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 232 error = img_first(imgp); 233 234 /* 235 * If the vnode has a registered vmspace, exec the vmspace 236 */ 237 if (error == -1 && imgp->vp->v_resident) { 238 error = exec_resident_imgact(imgp); 239 } 240 241 /* 242 * Loop through the list of image activators, calling each one. 243 * An activator returns -1 if there is no match, 0 on success, 244 * and an error otherwise. 245 */ 246 for (i = 0; error == -1 && execsw[i]; ++i) { 247 if (execsw[i]->ex_imgact == NULL || 248 execsw[i]->ex_imgact == img_first) { 249 continue; 250 } 251 error = (*execsw[i]->ex_imgact)(imgp); 252 } 253 254 if (error) { 255 if (error == -1) 256 error = ENOEXEC; 257 goto exec_fail_dealloc; 258 } 259 260 /* 261 * Special interpreter operation, cleanup and loop up to try to 262 * activate the interpreter. 263 */ 264 if (imgp->interpreted) { 265 exec_unmap_first_page(imgp); 266 nlookup_done(nd); 267 vrele(imgp->vp); 268 imgp->vp = NULL; 269 error = nlookup_init(nd, imgp->interpreter_name, UIO_SYSSPACE, 270 NLC_FOLLOW); 271 if (error) 272 goto exec_fail; 273 goto interpret; 274 } 275 276 /* 277 * Copy out strings (args and env) and initialize stack base 278 */ 279 stack_base = exec_copyout_strings(imgp); 280 p->p_vmspace->vm_minsaddr = (char *)stack_base; 281 282 /* 283 * If custom stack fixup routine present for this process 284 * let it do the stack setup. If we are running a resident 285 * image there is no auxinfo or other image activator context 286 * so don't try to add fixups to the stack. 287 * 288 * Else stuff argument count as first item on stack 289 */ 290 if (p->p_sysent->sv_fixup && imgp->resident == 0) 291 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 292 else 293 suword(--stack_base, imgp->args->argc); 294 295 /* 296 * For security and other reasons, the file descriptor table cannot 297 * be shared after an exec. 298 */ 299 if (p->p_fd->fd_refcnt > 1) { 300 struct filedesc *tmp; 301 302 tmp = fdcopy(p); 303 fdfree(p); 304 p->p_fd = tmp; 305 } 306 307 /* 308 * For security and other reasons, signal handlers cannot 309 * be shared after an exec. The new proces gets a copy of the old 310 * handlers. In execsigs(), the new process will have its signals 311 * reset. 312 */ 313 if (p->p_procsig->ps_refcnt > 1) { 314 struct procsig *newprocsig; 315 316 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 317 M_SUBPROC, M_WAITOK); 318 bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); 319 p->p_procsig->ps_refcnt--; 320 p->p_procsig = newprocsig; 321 p->p_procsig->ps_refcnt = 1; 322 if (p->p_sigacts == &p->p_addr->u_sigacts) 323 panic("shared procsig but private sigacts?"); 324 325 p->p_addr->u_sigacts = *p->p_sigacts; 326 p->p_sigacts = &p->p_addr->u_sigacts; 327 } 328 329 /* Stop profiling */ 330 stopprofclock(p); 331 332 /* close files on exec */ 333 fdcloseexec(p); 334 335 /* reset caught signals */ 336 execsigs(p); 337 338 /* name this process - nameiexec(p, ndp) */ 339 len = min(nd->nl_ncp->nc_nlen, MAXCOMLEN); 340 bcopy(nd->nl_ncp->nc_name, p->p_comm, len); 341 p->p_comm[len] = 0; 342 bcopy(p->p_comm, p->p_lwp.lwp_thread->td_comm, MAXCOMLEN+1); 343 344 /* 345 * mark as execed, wakeup the process that vforked (if any) and tell 346 * it that it now has its own resources back 347 */ 348 p->p_flag |= P_EXEC; 349 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 350 p->p_flag &= ~P_PPWAIT; 351 wakeup((caddr_t)p->p_pptr); 352 } 353 354 /* 355 * Implement image setuid/setgid. 356 * 357 * Don't honor setuid/setgid if the filesystem prohibits it or if 358 * the process is being traced. 359 */ 360 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 361 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 362 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 363 (p->p_flag & P_TRACED) == 0) { 364 /* 365 * Turn off syscall tracing for set-id programs, except for 366 * root. Record any set-id flags first to make sure that 367 * we do not regain any tracing during a possible block. 368 */ 369 setsugid(); 370 if (p->p_tracenode && suser(td) != 0) { 371 ktrdestroy(&p->p_tracenode); 372 p->p_traceflag = 0; 373 } 374 /* Close any file descriptors 0..2 that reference procfs */ 375 setugidsafety(p); 376 /* Make sure file descriptors 0..2 are in use. */ 377 error = fdcheckstd(p); 378 if (error != 0) 379 goto exec_fail_dealloc; 380 /* 381 * Set the new credentials. 382 */ 383 cratom(&p->p_ucred); 384 if (attr.va_mode & VSUID) 385 change_euid(attr.va_uid); 386 if (attr.va_mode & VSGID) 387 p->p_ucred->cr_gid = attr.va_gid; 388 389 /* 390 * Clear local varsym variables 391 */ 392 varsymset_clean(&p->p_varsymset); 393 } else { 394 if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && 395 p->p_ucred->cr_gid == p->p_ucred->cr_rgid) 396 p->p_flag &= ~P_SUGID; 397 } 398 399 /* 400 * Implement correct POSIX saved-id behavior. 401 */ 402 if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || 403 p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { 404 cratom(&p->p_ucred); 405 p->p_ucred->cr_svuid = p->p_ucred->cr_uid; 406 p->p_ucred->cr_svgid = p->p_ucred->cr_gid; 407 } 408 409 /* 410 * Store the vp for use in procfs 411 */ 412 if (p->p_textvp) /* release old reference */ 413 vrele(p->p_textvp); 414 p->p_textvp = imgp->vp; 415 vref(p->p_textvp); 416 417 /* 418 * Notify others that we exec'd, and clear the P_INEXEC flag 419 * as we're now a bona fide freshly-execed process. 420 */ 421 KNOTE(&p->p_klist, NOTE_EXEC); 422 p->p_flag &= ~P_INEXEC; 423 424 /* 425 * If tracing the process, trap to debugger so breakpoints 426 * can be set before the program executes. 427 */ 428 STOPEVENT(p, S_EXEC, 0); 429 430 if (p->p_flag & P_TRACED) 431 psignal(p, SIGTRAP); 432 433 /* clear "fork but no exec" flag, as we _are_ execing */ 434 p->p_acflag &= ~AFORK; 435 436 /* Set values passed into the program in registers. */ 437 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 438 imgp->ps_strings); 439 440 /* Free any previous argument cache */ 441 if (p->p_args && --p->p_args->ar_ref == 0) 442 FREE(p->p_args, M_PARGS); 443 p->p_args = NULL; 444 445 /* Cache arguments if they fit inside our allowance */ 446 i = imgp->args->begin_envv - imgp->args->begin_argv; 447 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 448 MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, 449 M_PARGS, M_WAITOK); 450 p->p_args->ar_ref = 1; 451 p->p_args->ar_length = i; 452 bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); 453 } 454 455 exec_fail_dealloc: 456 457 /* 458 * free various allocated resources 459 */ 460 if (imgp->firstpage) 461 exec_unmap_first_page(imgp); 462 463 if (imgp->vp) { 464 vrele(imgp->vp); 465 imgp->vp = NULL; 466 } 467 468 if (error == 0) { 469 ++mycpu->gd_cnt.v_exec; 470 return (0); 471 } 472 473 exec_fail: 474 /* we're done here, clear P_INEXEC */ 475 p->p_flag &= ~P_INEXEC; 476 if (imgp->vmspace_destroyed) { 477 /* sorry, no more process anymore. exit gracefully */ 478 exit1(W_EXITCODE(0, SIGABRT)); 479 /* NOT REACHED */ 480 return(0); 481 } else { 482 return(error); 483 } 484 } 485 486 /* 487 * execve() system call. 488 */ 489 int 490 sys_execve(struct execve_args *uap) 491 { 492 struct nlookupdata nd; 493 struct image_args args; 494 int error; 495 496 error = nlookup_init(&nd, uap->fname, UIO_USERSPACE, NLC_FOLLOW); 497 if (error == 0) { 498 error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, 499 uap->argv, uap->envv); 500 } 501 if (error == 0) 502 error = kern_execve(&nd, &args); 503 nlookup_done(&nd); 504 exec_free_args(&args); 505 506 /* 507 * The syscall result is returned in registers to the new program. 508 * Linux will register %edx as an atexit function and we must be 509 * sure to set it to 0. XXX 510 */ 511 if (error == 0) 512 uap->sysmsg_result64 = 0; 513 514 return (error); 515 } 516 517 int 518 exec_map_first_page(struct image_params *imgp) 519 { 520 int rv, i; 521 int initial_pagein; 522 vm_page_t ma[VM_INITIAL_PAGEIN]; 523 vm_page_t m; 524 vm_object_t object; 525 526 if (imgp->firstpage) 527 exec_unmap_first_page(imgp); 528 529 /* 530 * The file has to be mappable. 531 */ 532 if ((object = imgp->vp->v_object) == NULL) 533 return (EIO); 534 535 /* 536 * We shouldn't need protection for vm_page_grab() but we certainly 537 * need it for the lookup loop below (lookup/busy race), since 538 * an interrupt can unbusy and free the page before our busy check. 539 */ 540 crit_enter(); 541 m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 542 543 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 544 ma[0] = m; 545 initial_pagein = VM_INITIAL_PAGEIN; 546 if (initial_pagein > object->size) 547 initial_pagein = object->size; 548 for (i = 1; i < initial_pagein; i++) { 549 if ((m = vm_page_lookup(object, i)) != NULL) { 550 if ((m->flags & PG_BUSY) || m->busy) 551 break; 552 if (m->valid) 553 break; 554 vm_page_busy(m); 555 } else { 556 m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 557 if (m == NULL) 558 break; 559 } 560 ma[i] = m; 561 } 562 initial_pagein = i; 563 564 /* 565 * get_pages unbusies all the requested pages except the 566 * primary page (at index 0 in this case). 567 */ 568 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 569 m = vm_page_lookup(object, 0); 570 571 if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { 572 if (m) { 573 vm_page_protect(m, VM_PROT_NONE); 574 vm_page_free(m); 575 } 576 crit_exit(); 577 return EIO; 578 } 579 } 580 vm_page_hold(m); 581 vm_page_wakeup(m); /* unbusy the page */ 582 crit_exit(); 583 584 imgp->firstpage = sf_buf_alloc(m, SFB_CPUPRIVATE); 585 imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); 586 587 return 0; 588 } 589 590 void 591 exec_unmap_first_page(struct image_params *imgp) 592 { 593 vm_page_t m; 594 595 crit_enter(); 596 if (imgp->firstpage != NULL) { 597 m = sf_buf_page(imgp->firstpage); 598 sf_buf_free(imgp->firstpage); 599 imgp->firstpage = NULL; 600 imgp->image_header = NULL; 601 vm_page_unhold(m); 602 } 603 crit_exit(); 604 } 605 606 /* 607 * Destroy old address space, and allocate a new stack 608 * The new stack is only SGROWSIZ large because it is grown 609 * automatically in trap.c. 610 */ 611 int 612 exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) 613 { 614 int error; 615 struct vmspace *vmspace = imgp->proc->p_vmspace; 616 vm_offset_t stack_addr = USRSTACK - maxssiz; 617 vm_map_t map; 618 619 imgp->vmspace_destroyed = 1; 620 621 /* 622 * Prevent a pending AIO from modifying the new address space. 623 */ 624 aio_proc_rundown(imgp->proc); 625 626 /* 627 * Blow away entire process VM, if address space not shared, 628 * otherwise, create a new VM space so that other threads are 629 * not disrupted. If we are execing a resident vmspace we 630 * create a duplicate of it and remap the stack. 631 * 632 * The exitingcnt test is not strictly necessary but has been 633 * included for code sanity (to make the code more deterministic). 634 */ 635 map = &vmspace->vm_map; 636 if (vmcopy) { 637 vmspace_exec(imgp->proc, vmcopy); 638 vmspace = imgp->proc->p_vmspace; 639 pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); 640 map = &vmspace->vm_map; 641 } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { 642 shmexit(vmspace); 643 if (vmspace->vm_upcalls) 644 upc_release(vmspace, &imgp->proc->p_lwp); 645 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 646 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 647 } else { 648 vmspace_exec(imgp->proc, NULL); 649 vmspace = imgp->proc->p_vmspace; 650 map = &vmspace->vm_map; 651 } 652 653 /* Allocate a new stack */ 654 error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, 655 VM_PROT_ALL, VM_PROT_ALL, 0); 656 if (error) 657 return (error); 658 659 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 660 * VM_STACK case, but they are still used to monitor the size of the 661 * process stack so we can check the stack rlimit. 662 */ 663 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 664 vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; 665 666 return(0); 667 } 668 669 /* 670 * Copy out argument and environment strings from the old process 671 * address space into the temporary string buffer. 672 */ 673 int 674 exec_copyin_args(struct image_args *args, char *fname, 675 enum exec_path_segflg segflg, char **argv, char **envv) 676 { 677 char *argp, *envp; 678 int error = 0; 679 size_t length; 680 681 bzero(args, sizeof(*args)); 682 args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 683 if (args->buf == NULL) 684 return (ENOMEM); 685 args->begin_argv = args->buf; 686 args->endp = args->begin_argv; 687 args->space = ARG_MAX; 688 689 args->fname = args->buf + ARG_MAX; 690 691 /* 692 * Copy the file name. 693 */ 694 if (segflg == PATH_SYSSPACE) { 695 error = copystr(fname, args->fname, PATH_MAX, &length); 696 } else if (segflg == PATH_USERSPACE) { 697 error = copyinstr(fname, args->fname, PATH_MAX, &length); 698 } 699 700 /* 701 * Extract argument strings. argv may not be NULL. The argv 702 * array is terminated by a NULL entry. We special-case the 703 * situation where argv[0] is NULL by passing { filename, NULL } 704 * to the new program to guarentee that the interpreter knows what 705 * file to open in case we exec an interpreted file. Note that 706 * a NULL argv[0] terminates the argv[] array. 707 * 708 * XXX the special-casing of argv[0] is historical and needs to be 709 * revisited. 710 */ 711 if (argv == NULL) 712 error = EFAULT; 713 if (error == 0) { 714 while ((argp = (caddr_t)(intptr_t)fuword(argv++)) != NULL) { 715 if (argp == (caddr_t)-1) { 716 error = EFAULT; 717 break; 718 } 719 error = copyinstr(argp, args->endp, 720 args->space, &length); 721 if (error) { 722 if (error == ENAMETOOLONG) 723 error = E2BIG; 724 break; 725 } 726 args->space -= length; 727 args->endp += length; 728 args->argc++; 729 } 730 if (args->argc == 0 && error == 0) { 731 length = strlen(args->fname) + 1; 732 if (length > args->space) { 733 error = E2BIG; 734 } else { 735 bcopy(args->fname, args->endp, length); 736 args->space -= length; 737 args->endp += length; 738 args->argc++; 739 } 740 } 741 } 742 743 args->begin_envv = args->endp; 744 745 /* 746 * extract environment strings. envv may be NULL. 747 */ 748 if (envv && error == 0) { 749 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 750 if (envp == (caddr_t) -1) { 751 error = EFAULT; 752 break; 753 } 754 error = copyinstr(envp, args->endp, args->space, 755 &length); 756 if (error) { 757 if (error == ENAMETOOLONG) 758 error = E2BIG; 759 break; 760 } 761 args->space -= length; 762 args->endp += length; 763 args->envc++; 764 } 765 } 766 return (error); 767 } 768 769 void 770 exec_free_args(struct image_args *args) 771 { 772 if (args->buf) { 773 kmem_free_wakeup(exec_map, 774 (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); 775 args->buf = NULL; 776 } 777 } 778 779 /* 780 * Copy strings out to the new process address space, constructing 781 * new arg and env vector tables. Return a pointer to the base 782 * so that it can be used as the initial stack pointer. 783 */ 784 register_t * 785 exec_copyout_strings(struct image_params *imgp) 786 { 787 int argc, envc, sgap; 788 char **vectp; 789 char *stringp, *destp; 790 register_t *stack_base; 791 struct ps_strings *arginfo; 792 int szsigcode; 793 794 /* 795 * Calculate string base and vector table pointers. 796 * Also deal with signal trampoline code for this exec type. 797 */ 798 arginfo = (struct ps_strings *)PS_STRINGS; 799 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 800 if (stackgap_random != 0) 801 sgap = ALIGN(arc4random() & (stackgap_random - 1)); 802 else 803 sgap = 0; 804 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - sgap - 805 roundup((ARG_MAX - imgp->args->space), sizeof(char *)); 806 807 /* 808 * install sigcode 809 */ 810 if (szsigcode) 811 copyout(imgp->proc->p_sysent->sv_sigcode, 812 ((caddr_t)arginfo - szsigcode), szsigcode); 813 814 /* 815 * If we have a valid auxargs ptr, prepare some room 816 * on the stack. 817 * 818 * The '+ 2' is for the null pointers at the end of each of the 819 * arg and env vector sets, and 'AT_COUNT*2' is room for the 820 * ELF Auxargs data. 821 */ 822 if (imgp->auxargs) { 823 vectp = (char **)(destp - (imgp->args->argc + 824 imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); 825 } else { 826 vectp = (char **)(destp - (imgp->args->argc + 827 imgp->args->envc + 2) * sizeof(char*)); 828 } 829 830 /* 831 * NOTE: don't bother aligning the stack here for GCC 2.x, it will 832 * be done in crt1.o. Note that GCC 3.x aligns the stack in main. 833 */ 834 835 /* 836 * vectp also becomes our initial stack base 837 */ 838 stack_base = (register_t *)vectp; 839 840 stringp = imgp->args->begin_argv; 841 argc = imgp->args->argc; 842 envc = imgp->args->envc; 843 844 /* 845 * Copy out strings - arguments and environment. 846 */ 847 copyout(stringp, destp, ARG_MAX - imgp->args->space); 848 849 /* 850 * Fill in "ps_strings" struct for ps, w, etc. 851 */ 852 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 853 suword(&arginfo->ps_nargvstr, argc); 854 855 /* 856 * Fill in argument portion of vector table. 857 */ 858 for (; argc > 0; --argc) { 859 suword(vectp++, (long)(intptr_t)destp); 860 while (*stringp++ != 0) 861 destp++; 862 destp++; 863 } 864 865 /* a null vector table pointer separates the argp's from the envp's */ 866 suword(vectp++, 0); 867 868 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 869 suword(&arginfo->ps_nenvstr, envc); 870 871 /* 872 * Fill in environment portion of vector table. 873 */ 874 for (; envc > 0; --envc) { 875 suword(vectp++, (long)(intptr_t)destp); 876 while (*stringp++ != 0) 877 destp++; 878 destp++; 879 } 880 881 /* end of vector table is a null pointer */ 882 suword(vectp, 0); 883 884 return (stack_base); 885 } 886 887 /* 888 * Check permissions of file to execute. 889 * Return 0 for success or error code on failure. 890 */ 891 int 892 exec_check_permissions(struct image_params *imgp) 893 { 894 struct proc *p = imgp->proc; 895 struct vnode *vp = imgp->vp; 896 struct vattr *attr = imgp->attr; 897 int error; 898 899 /* Get file attributes */ 900 error = VOP_GETATTR(vp, attr); 901 if (error) 902 return (error); 903 904 /* 905 * 1) Check if file execution is disabled for the filesystem that this 906 * file resides on. 907 * 2) Insure that at least one execute bit is on - otherwise root 908 * will always succeed, and we don't want to happen unless the 909 * file really is executable. 910 * 3) Insure that the file is a regular file. 911 */ 912 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 913 ((attr->va_mode & 0111) == 0) || 914 (attr->va_type != VREG)) { 915 return (EACCES); 916 } 917 918 /* 919 * Zero length files can't be exec'd 920 */ 921 if (attr->va_size == 0) 922 return (ENOEXEC); 923 924 /* 925 * Check for execute permission to file based on current credentials. 926 */ 927 error = VOP_ACCESS(vp, VEXEC, p->p_ucred); 928 if (error) 929 return (error); 930 931 /* 932 * Check number of open-for-writes on the file and deny execution 933 * if there are any. 934 */ 935 if (vp->v_writecount) 936 return (ETXTBSY); 937 938 /* 939 * Call filesystem specific open routine, which allows us to read, 940 * write, and mmap the file. Without the VOP_OPEN we can only 941 * stat the file. 942 */ 943 error = VOP_OPEN(vp, FREAD, p->p_ucred, NULL); 944 if (error) 945 return (error); 946 947 return (0); 948 } 949 950 /* 951 * Exec handler registration 952 */ 953 int 954 exec_register(const struct execsw *execsw_arg) 955 { 956 const struct execsw **es, **xs, **newexecsw; 957 int count = 2; /* New slot and trailing NULL */ 958 959 if (execsw) 960 for (es = execsw; *es; es++) 961 count++; 962 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 963 if (newexecsw == NULL) 964 return ENOMEM; 965 xs = newexecsw; 966 if (execsw) 967 for (es = execsw; *es; es++) 968 *xs++ = *es; 969 *xs++ = execsw_arg; 970 *xs = NULL; 971 if (execsw) 972 free(execsw, M_TEMP); 973 execsw = newexecsw; 974 return 0; 975 } 976 977 int 978 exec_unregister(const struct execsw *execsw_arg) 979 { 980 const struct execsw **es, **xs, **newexecsw; 981 int count = 1; 982 983 if (execsw == NULL) 984 panic("unregister with no handlers left?"); 985 986 for (es = execsw; *es; es++) { 987 if (*es == execsw_arg) 988 break; 989 } 990 if (*es == NULL) 991 return ENOENT; 992 for (es = execsw; *es; es++) 993 if (*es != execsw_arg) 994 count++; 995 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 996 if (newexecsw == NULL) 997 return ENOMEM; 998 xs = newexecsw; 999 for (es = execsw; *es; es++) 1000 if (*es != execsw_arg) 1001 *xs++ = *es; 1002 *xs = NULL; 1003 if (execsw) 1004 free(execsw, M_TEMP); 1005 execsw = newexecsw; 1006 return 0; 1007 } 1008