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 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_ktrace.h" 33 #include "opt_vm.h" 34 35 #include <sys/param.h> 36 #include <sys/capsicum.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/sysproto.h> 42 #include <sys/signalvar.h> 43 #include <sys/kernel.h> 44 #include <sys/mount.h> 45 #include <sys/filedesc.h> 46 #include <sys/fcntl.h> 47 #include <sys/acct.h> 48 #include <sys/exec.h> 49 #include <sys/imgact.h> 50 #include <sys/imgact_elf.h> 51 #include <sys/wait.h> 52 #include <sys/malloc.h> 53 #include <sys/priv.h> 54 #include <sys/proc.h> 55 #include <sys/pioctl.h> 56 #include <sys/namei.h> 57 #include <sys/resourcevar.h> 58 #include <sys/rwlock.h> 59 #include <sys/sched.h> 60 #include <sys/sdt.h> 61 #include <sys/sf_buf.h> 62 #include <sys/syscallsubr.h> 63 #include <sys/sysent.h> 64 #include <sys/shm.h> 65 #include <sys/sysctl.h> 66 #include <sys/vnode.h> 67 #include <sys/stat.h> 68 #ifdef KTRACE 69 #include <sys/ktrace.h> 70 #endif 71 72 #include <vm/vm.h> 73 #include <vm/vm_param.h> 74 #include <vm/pmap.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_map.h> 77 #include <vm/vm_kern.h> 78 #include <vm/vm_extern.h> 79 #include <vm/vm_object.h> 80 #include <vm/vm_pager.h> 81 82 #ifdef HWPMC_HOOKS 83 #include <sys/pmckern.h> 84 #endif 85 86 #include <machine/reg.h> 87 88 #include <security/audit/audit.h> 89 #include <security/mac/mac_framework.h> 90 91 #ifdef KDTRACE_HOOKS 92 #include <sys/dtrace_bsd.h> 93 dtrace_execexit_func_t dtrace_fasttrap_exec; 94 #endif 95 96 SDT_PROVIDER_DECLARE(proc); 97 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 98 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 99 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 100 101 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 102 103 int coredump_pack_fileinfo = 1; 104 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 105 &coredump_pack_fileinfo, 0, 106 "Enable file path packing in 'procstat -f' coredump notes"); 107 108 int coredump_pack_vmmapinfo = 1; 109 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 110 &coredump_pack_vmmapinfo, 0, 111 "Enable file path packing in 'procstat -v' coredump notes"); 112 113 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 114 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 115 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 116 static int do_execve(struct thread *td, struct image_args *args, 117 struct mac *mac_p); 118 119 /* XXX This should be vm_size_t. */ 120 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD, 121 NULL, 0, sysctl_kern_ps_strings, "LU", ""); 122 123 /* XXX This should be vm_size_t. */ 124 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 125 CTLFLAG_CAPRD, NULL, 0, sysctl_kern_usrstack, "LU", ""); 126 127 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD, 128 NULL, 0, sysctl_kern_stackprot, "I", ""); 129 130 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 131 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 132 &ps_arg_cache_limit, 0, ""); 133 134 static int disallow_high_osrel; 135 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 136 &disallow_high_osrel, 0, 137 "Disallow execution of binaries built for higher version of the world"); 138 139 static int map_at_zero = 0; 140 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 141 "Permit processes to map an object at virtual address 0."); 142 143 static int 144 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 145 { 146 struct proc *p; 147 int error; 148 149 p = curproc; 150 #ifdef SCTL_MASK32 151 if (req->flags & SCTL_MASK32) { 152 unsigned int val; 153 val = (unsigned int)p->p_sysent->sv_psstrings; 154 error = SYSCTL_OUT(req, &val, sizeof(val)); 155 } else 156 #endif 157 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 158 sizeof(p->p_sysent->sv_psstrings)); 159 return error; 160 } 161 162 static int 163 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 164 { 165 struct proc *p; 166 int error; 167 168 p = curproc; 169 #ifdef SCTL_MASK32 170 if (req->flags & SCTL_MASK32) { 171 unsigned int val; 172 val = (unsigned int)p->p_sysent->sv_usrstack; 173 error = SYSCTL_OUT(req, &val, sizeof(val)); 174 } else 175 #endif 176 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 177 sizeof(p->p_sysent->sv_usrstack)); 178 return error; 179 } 180 181 static int 182 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 183 { 184 struct proc *p; 185 186 p = curproc; 187 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 188 sizeof(p->p_sysent->sv_stackprot))); 189 } 190 191 /* 192 * Each of the items is a pointer to a `const struct execsw', hence the 193 * double pointer here. 194 */ 195 static const struct execsw **execsw; 196 197 #ifndef _SYS_SYSPROTO_H_ 198 struct execve_args { 199 char *fname; 200 char **argv; 201 char **envv; 202 }; 203 #endif 204 205 int 206 sys_execve(struct thread *td, struct execve_args *uap) 207 { 208 struct image_args args; 209 struct vmspace *oldvmspace; 210 int error; 211 212 error = pre_execve(td, &oldvmspace); 213 if (error != 0) 214 return (error); 215 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 216 uap->argv, uap->envv); 217 if (error == 0) 218 error = kern_execve(td, &args, NULL); 219 post_execve(td, error, oldvmspace); 220 return (error); 221 } 222 223 #ifndef _SYS_SYSPROTO_H_ 224 struct fexecve_args { 225 int fd; 226 char **argv; 227 char **envv; 228 } 229 #endif 230 int 231 sys_fexecve(struct thread *td, struct fexecve_args *uap) 232 { 233 struct image_args args; 234 struct vmspace *oldvmspace; 235 int error; 236 237 error = pre_execve(td, &oldvmspace); 238 if (error != 0) 239 return (error); 240 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 241 uap->argv, uap->envv); 242 if (error == 0) { 243 args.fd = uap->fd; 244 error = kern_execve(td, &args, NULL); 245 } 246 post_execve(td, error, oldvmspace); 247 return (error); 248 } 249 250 #ifndef _SYS_SYSPROTO_H_ 251 struct __mac_execve_args { 252 char *fname; 253 char **argv; 254 char **envv; 255 struct mac *mac_p; 256 }; 257 #endif 258 259 int 260 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 261 { 262 #ifdef MAC 263 struct image_args args; 264 struct vmspace *oldvmspace; 265 int error; 266 267 error = pre_execve(td, &oldvmspace); 268 if (error != 0) 269 return (error); 270 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 271 uap->argv, uap->envv); 272 if (error == 0) 273 error = kern_execve(td, &args, uap->mac_p); 274 post_execve(td, error, oldvmspace); 275 return (error); 276 #else 277 return (ENOSYS); 278 #endif 279 } 280 281 int 282 pre_execve(struct thread *td, struct vmspace **oldvmspace) 283 { 284 struct proc *p; 285 int error; 286 287 KASSERT(td == curthread, ("non-current thread %p", td)); 288 error = 0; 289 p = td->td_proc; 290 if ((p->p_flag & P_HADTHREADS) != 0) { 291 PROC_LOCK(p); 292 if (thread_single(p, SINGLE_BOUNDARY) != 0) 293 error = ERESTART; 294 PROC_UNLOCK(p); 295 } 296 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 297 ("nested execve")); 298 *oldvmspace = p->p_vmspace; 299 return (error); 300 } 301 302 void 303 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 304 { 305 struct proc *p; 306 307 KASSERT(td == curthread, ("non-current thread %p", td)); 308 p = td->td_proc; 309 if ((p->p_flag & P_HADTHREADS) != 0) { 310 PROC_LOCK(p); 311 /* 312 * If success, we upgrade to SINGLE_EXIT state to 313 * force other threads to suicide. 314 */ 315 if (error == 0) 316 thread_single(p, SINGLE_EXIT); 317 else 318 thread_single_end(p, SINGLE_BOUNDARY); 319 PROC_UNLOCK(p); 320 } 321 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 322 KASSERT(p->p_vmspace != oldvmspace, 323 ("oldvmspace still used")); 324 vmspace_free(oldvmspace); 325 td->td_pflags &= ~TDP_EXECVMSPC; 326 } 327 } 328 329 /* 330 * XXX: kern_execve has the astonishing property of not always returning to 331 * the caller. If sufficiently bad things happen during the call to 332 * do_execve(), it can end up calling exit1(); as a result, callers must 333 * avoid doing anything which they might need to undo (e.g., allocating 334 * memory). 335 */ 336 int 337 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 338 { 339 340 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 341 args->begin_envv - args->begin_argv); 342 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 343 args->endp - args->begin_envv); 344 return (do_execve(td, args, mac_p)); 345 } 346 347 /* 348 * In-kernel implementation of execve(). All arguments are assumed to be 349 * userspace pointers from the passed thread. 350 */ 351 static int 352 do_execve(td, args, mac_p) 353 struct thread *td; 354 struct image_args *args; 355 struct mac *mac_p; 356 { 357 struct proc *p = td->td_proc; 358 struct nameidata nd; 359 struct ucred *newcred = NULL, *oldcred; 360 struct uidinfo *euip = NULL; 361 register_t *stack_base; 362 int error, i; 363 struct image_params image_params, *imgp; 364 struct vattr attr; 365 int (*img_first)(struct image_params *); 366 struct pargs *oldargs = NULL, *newargs = NULL; 367 struct sigacts *oldsigacts, *newsigacts; 368 #ifdef KTRACE 369 struct vnode *tracevp = NULL; 370 struct ucred *tracecred = NULL; 371 #endif 372 struct vnode *oldtextvp = NULL, *newtextvp; 373 cap_rights_t rights; 374 int credential_changing; 375 int textset; 376 #ifdef MAC 377 struct label *interpvplabel = NULL; 378 int will_transition; 379 #endif 380 #ifdef HWPMC_HOOKS 381 struct pmckern_procexec pe; 382 #endif 383 static const char fexecv_proc_title[] = "(fexecv)"; 384 385 imgp = &image_params; 386 387 /* 388 * Lock the process and set the P_INEXEC flag to indicate that 389 * it should be left alone until we're done here. This is 390 * necessary to avoid race conditions - e.g. in ptrace() - 391 * that might allow a local user to illicitly obtain elevated 392 * privileges. 393 */ 394 PROC_LOCK(p); 395 KASSERT((p->p_flag & P_INEXEC) == 0, 396 ("%s(): process already has P_INEXEC flag", __func__)); 397 p->p_flag |= P_INEXEC; 398 PROC_UNLOCK(p); 399 400 /* 401 * Initialize part of the common data 402 */ 403 bzero(imgp, sizeof(*imgp)); 404 imgp->proc = p; 405 imgp->attr = &attr; 406 imgp->args = args; 407 408 #ifdef MAC 409 error = mac_execve_enter(imgp, mac_p); 410 if (error) 411 goto exec_fail; 412 #endif 413 414 /* 415 * Translate the file name. namei() returns a vnode pointer 416 * in ni_vp amoung other things. 417 * 418 * XXXAUDIT: It would be desirable to also audit the name of the 419 * interpreter if this is an interpreted binary. 420 */ 421 if (args->fname != NULL) { 422 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 423 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 424 } 425 426 SDT_PROBE1(proc, , , exec, args->fname); 427 428 interpret: 429 if (args->fname != NULL) { 430 #ifdef CAPABILITY_MODE 431 /* 432 * While capability mode can't reach this point via direct 433 * path arguments to execve(), we also don't allow 434 * interpreters to be used in capability mode (for now). 435 * Catch indirect lookups and return a permissions error. 436 */ 437 if (IN_CAPABILITY_MODE(td)) { 438 error = ECAPMODE; 439 goto exec_fail; 440 } 441 #endif 442 error = namei(&nd); 443 if (error) 444 goto exec_fail; 445 446 newtextvp = nd.ni_vp; 447 imgp->vp = newtextvp; 448 } else { 449 AUDIT_ARG_FD(args->fd); 450 /* 451 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 452 */ 453 error = fgetvp_exec(td, args->fd, 454 cap_rights_init(&rights, CAP_FEXECVE), &newtextvp); 455 if (error) 456 goto exec_fail; 457 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY); 458 AUDIT_ARG_VNODE1(newtextvp); 459 imgp->vp = newtextvp; 460 } 461 462 /* 463 * Check file permissions (also 'opens' file) 464 */ 465 error = exec_check_permissions(imgp); 466 if (error) 467 goto exec_fail_dealloc; 468 469 imgp->object = imgp->vp->v_object; 470 if (imgp->object != NULL) 471 vm_object_reference(imgp->object); 472 473 /* 474 * Set VV_TEXT now so no one can write to the executable while we're 475 * activating it. 476 * 477 * Remember if this was set before and unset it in case this is not 478 * actually an executable image. 479 */ 480 textset = VOP_IS_TEXT(imgp->vp); 481 VOP_SET_TEXT(imgp->vp); 482 483 error = exec_map_first_page(imgp); 484 if (error) 485 goto exec_fail_dealloc; 486 487 imgp->proc->p_osrel = 0; 488 /* 489 * If the current process has a special image activator it 490 * wants to try first, call it. For example, emulating shell 491 * scripts differently. 492 */ 493 error = -1; 494 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 495 error = img_first(imgp); 496 497 /* 498 * Loop through the list of image activators, calling each one. 499 * An activator returns -1 if there is no match, 0 on success, 500 * and an error otherwise. 501 */ 502 for (i = 0; error == -1 && execsw[i]; ++i) { 503 if (execsw[i]->ex_imgact == NULL || 504 execsw[i]->ex_imgact == img_first) { 505 continue; 506 } 507 error = (*execsw[i]->ex_imgact)(imgp); 508 } 509 510 if (error) { 511 if (error == -1) { 512 if (textset == 0) 513 VOP_UNSET_TEXT(imgp->vp); 514 error = ENOEXEC; 515 } 516 goto exec_fail_dealloc; 517 } 518 519 /* 520 * Special interpreter operation, cleanup and loop up to try to 521 * activate the interpreter. 522 */ 523 if (imgp->interpreted) { 524 exec_unmap_first_page(imgp); 525 /* 526 * VV_TEXT needs to be unset for scripts. There is a short 527 * period before we determine that something is a script where 528 * VV_TEXT will be set. The vnode lock is held over this 529 * entire period so nothing should illegitimately be blocked. 530 */ 531 VOP_UNSET_TEXT(imgp->vp); 532 /* free name buffer and old vnode */ 533 if (args->fname != NULL) 534 NDFREE(&nd, NDF_ONLY_PNBUF); 535 #ifdef MAC 536 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 537 #endif 538 if (imgp->opened) { 539 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 540 imgp->opened = 0; 541 } 542 vput(newtextvp); 543 vm_object_deallocate(imgp->object); 544 imgp->object = NULL; 545 /* set new name to that of the interpreter */ 546 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 547 UIO_SYSSPACE, imgp->interpreter_name, td); 548 args->fname = imgp->interpreter_name; 549 goto interpret; 550 } 551 552 /* 553 * NB: We unlock the vnode here because it is believed that none 554 * of the sv_copyout_strings/sv_fixup operations require the vnode. 555 */ 556 VOP_UNLOCK(imgp->vp, 0); 557 558 /* 559 * Do the best to calculate the full path to the image file. 560 */ 561 if (imgp->auxargs != NULL && 562 ((args->fname != NULL && args->fname[0] == '/') || 563 vn_fullpath(td, imgp->vp, &imgp->execpath, &imgp->freepath) != 0)) 564 imgp->execpath = args->fname; 565 566 if (disallow_high_osrel && 567 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 568 error = ENOEXEC; 569 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 570 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 571 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 572 goto exec_fail_dealloc; 573 } 574 575 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 576 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 577 sys_cap_enter(td, NULL); 578 579 /* 580 * Copy out strings (args and env) and initialize stack base 581 */ 582 if (p->p_sysent->sv_copyout_strings) 583 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 584 else 585 stack_base = exec_copyout_strings(imgp); 586 587 /* 588 * If custom stack fixup routine present for this process 589 * let it do the stack setup. 590 * Else stuff argument count as first item on stack 591 */ 592 if (p->p_sysent->sv_fixup != NULL) 593 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 594 else 595 suword(--stack_base, imgp->args->argc); 596 597 if (args->fdp != NULL) { 598 /* Install a brand new file descriptor table. */ 599 fdinstall_remapped(td, args->fdp); 600 args->fdp = NULL; 601 } else { 602 /* 603 * Keep on using the existing file descriptor table. For 604 * security and other reasons, the file descriptor table 605 * cannot be shared after an exec. 606 */ 607 fdunshare(td); 608 /* close files on exec */ 609 fdcloseexec(td); 610 } 611 612 /* 613 * Malloc things before we need locks. 614 */ 615 i = imgp->args->begin_envv - imgp->args->begin_argv; 616 /* Cache arguments if they fit inside our allowance */ 617 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 618 newargs = pargs_alloc(i); 619 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 620 } 621 622 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 623 624 /* 625 * For security and other reasons, signal handlers cannot 626 * be shared after an exec. The new process gets a copy of the old 627 * handlers. In execsigs(), the new process will have its signals 628 * reset. 629 */ 630 if (sigacts_shared(p->p_sigacts)) { 631 oldsigacts = p->p_sigacts; 632 newsigacts = sigacts_alloc(); 633 sigacts_copy(newsigacts, oldsigacts); 634 } else { 635 oldsigacts = NULL; 636 newsigacts = NULL; /* satisfy gcc */ 637 } 638 639 PROC_LOCK(p); 640 if (oldsigacts) 641 p->p_sigacts = newsigacts; 642 oldcred = p->p_ucred; 643 /* Stop profiling */ 644 stopprofclock(p); 645 646 /* reset caught signals */ 647 execsigs(p); 648 649 /* name this process - nameiexec(p, ndp) */ 650 bzero(p->p_comm, sizeof(p->p_comm)); 651 if (args->fname) 652 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 653 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 654 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 655 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 656 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 657 #ifdef KTR 658 sched_clear_tdname(td); 659 #endif 660 661 /* 662 * mark as execed, wakeup the process that vforked (if any) and tell 663 * it that it now has its own resources back 664 */ 665 p->p_flag |= P_EXEC; 666 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 667 p->p_flag2 &= ~P2_NOTRACE; 668 if (p->p_flag & P_PPWAIT) { 669 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 670 cv_broadcast(&p->p_pwait); 671 } 672 673 /* 674 * Implement image setuid/setgid. 675 * 676 * Don't honor setuid/setgid if the filesystem prohibits it or if 677 * the process is being traced. 678 * 679 * We disable setuid/setgid/etc in compatibility mode on the basis 680 * that most setugid applications are not written with that 681 * environment in mind, and will therefore almost certainly operate 682 * incorrectly. In principle there's no reason that setugid 683 * applications might not be useful in capability mode, so we may want 684 * to reconsider this conservative design choice in the future. 685 * 686 * XXXMAC: For the time being, use NOSUID to also prohibit 687 * transitions on the file system. 688 */ 689 credential_changing = 0; 690 credential_changing |= (attr.va_mode & S_ISUID) && oldcred->cr_uid != 691 attr.va_uid; 692 credential_changing |= (attr.va_mode & S_ISGID) && oldcred->cr_gid != 693 attr.va_gid; 694 #ifdef MAC 695 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 696 interpvplabel, imgp); 697 credential_changing |= will_transition; 698 #endif 699 700 if (credential_changing && 701 #ifdef CAPABILITY_MODE 702 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 703 #endif 704 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 705 (p->p_flag & P_TRACED) == 0) { 706 /* 707 * Turn off syscall tracing for set-id programs, except for 708 * root. Record any set-id flags first to make sure that 709 * we do not regain any tracing during a possible block. 710 */ 711 setsugid(p); 712 713 #ifdef KTRACE 714 if (p->p_tracecred != NULL && 715 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 716 ktrprocexec(p, &tracecred, &tracevp); 717 #endif 718 /* 719 * Close any file descriptors 0..2 that reference procfs, 720 * then make sure file descriptors 0..2 are in use. 721 * 722 * Both fdsetugidsafety() and fdcheckstd() may call functions 723 * taking sleepable locks, so temporarily drop our locks. 724 */ 725 PROC_UNLOCK(p); 726 VOP_UNLOCK(imgp->vp, 0); 727 fdsetugidsafety(td); 728 error = fdcheckstd(td); 729 if (error != 0) 730 goto done1; 731 newcred = crdup(oldcred); 732 euip = uifind(attr.va_uid); 733 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 734 PROC_LOCK(p); 735 /* 736 * Set the new credentials. 737 */ 738 if (attr.va_mode & S_ISUID) 739 change_euid(newcred, euip); 740 if (attr.va_mode & S_ISGID) 741 change_egid(newcred, attr.va_gid); 742 #ifdef MAC 743 if (will_transition) { 744 mac_vnode_execve_transition(oldcred, newcred, imgp->vp, 745 interpvplabel, imgp); 746 } 747 #endif 748 /* 749 * Implement correct POSIX saved-id behavior. 750 * 751 * XXXMAC: Note that the current logic will save the 752 * uid and gid if a MAC domain transition occurs, even 753 * though maybe it shouldn't. 754 */ 755 change_svuid(newcred, newcred->cr_uid); 756 change_svgid(newcred, newcred->cr_gid); 757 proc_set_cred(p, newcred); 758 } else { 759 if (oldcred->cr_uid == oldcred->cr_ruid && 760 oldcred->cr_gid == oldcred->cr_rgid) 761 p->p_flag &= ~P_SUGID; 762 /* 763 * Implement correct POSIX saved-id behavior. 764 * 765 * XXX: It's not clear that the existing behavior is 766 * POSIX-compliant. A number of sources indicate that the 767 * saved uid/gid should only be updated if the new ruid is 768 * not equal to the old ruid, or the new euid is not equal 769 * to the old euid and the new euid is not equal to the old 770 * ruid. The FreeBSD code always updates the saved uid/gid. 771 * Also, this code uses the new (replaced) euid and egid as 772 * the source, which may or may not be the right ones to use. 773 */ 774 if (oldcred->cr_svuid != oldcred->cr_uid || 775 oldcred->cr_svgid != oldcred->cr_gid) { 776 PROC_UNLOCK(p); 777 VOP_UNLOCK(imgp->vp, 0); 778 newcred = crdup(oldcred); 779 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 780 PROC_LOCK(p); 781 change_svuid(newcred, newcred->cr_uid); 782 change_svgid(newcred, newcred->cr_gid); 783 proc_set_cred(p, newcred); 784 } 785 } 786 787 /* 788 * Store the vp for use in procfs. This vnode was referenced by namei 789 * or fgetvp_exec. 790 */ 791 oldtextvp = p->p_textvp; 792 p->p_textvp = newtextvp; 793 794 #ifdef KDTRACE_HOOKS 795 /* 796 * Tell the DTrace fasttrap provider about the exec if it 797 * has declared an interest. 798 */ 799 if (dtrace_fasttrap_exec) 800 dtrace_fasttrap_exec(p); 801 #endif 802 803 /* 804 * Notify others that we exec'd, and clear the P_INEXEC flag 805 * as we're now a bona fide freshly-execed process. 806 */ 807 KNOTE_LOCKED(&p->p_klist, NOTE_EXEC); 808 p->p_flag &= ~P_INEXEC; 809 810 /* clear "fork but no exec" flag, as we _are_ execing */ 811 p->p_acflag &= ~AFORK; 812 813 /* 814 * Free any previous argument cache and replace it with 815 * the new argument cache, if any. 816 */ 817 oldargs = p->p_args; 818 p->p_args = newargs; 819 newargs = NULL; 820 821 #ifdef HWPMC_HOOKS 822 /* 823 * Check if system-wide sampling is in effect or if the 824 * current process is using PMCs. If so, do exec() time 825 * processing. This processing needs to happen AFTER the 826 * P_INEXEC flag is cleared. 827 * 828 * The proc lock needs to be released before taking the PMC 829 * SX. 830 */ 831 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 832 PROC_UNLOCK(p); 833 VOP_UNLOCK(imgp->vp, 0); 834 pe.pm_credentialschanged = credential_changing; 835 pe.pm_entryaddr = imgp->entry_addr; 836 837 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 838 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 839 } else 840 PROC_UNLOCK(p); 841 #else /* !HWPMC_HOOKS */ 842 PROC_UNLOCK(p); 843 #endif 844 845 /* Set values passed into the program in registers. */ 846 if (p->p_sysent->sv_setregs) 847 (*p->p_sysent->sv_setregs)(td, imgp, 848 (u_long)(uintptr_t)stack_base); 849 else 850 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 851 852 vfs_mark_atime(imgp->vp, td->td_ucred); 853 854 SDT_PROBE1(proc, , , exec__success, args->fname); 855 856 VOP_UNLOCK(imgp->vp, 0); 857 done1: 858 /* 859 * Free any resources malloc'd earlier that we didn't use. 860 */ 861 if (euip != NULL) 862 uifree(euip); 863 if (newcred != NULL) 864 crfree(oldcred); 865 866 /* 867 * Handle deferred decrement of ref counts. 868 */ 869 if (oldtextvp != NULL) 870 vrele(oldtextvp); 871 #ifdef KTRACE 872 if (tracevp != NULL) 873 vrele(tracevp); 874 if (tracecred != NULL) 875 crfree(tracecred); 876 #endif 877 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 878 pargs_drop(oldargs); 879 pargs_drop(newargs); 880 if (oldsigacts != NULL) 881 sigacts_free(oldsigacts); 882 883 exec_fail_dealloc: 884 885 /* 886 * free various allocated resources 887 */ 888 if (imgp->firstpage != NULL) 889 exec_unmap_first_page(imgp); 890 891 if (imgp->vp != NULL) { 892 if (args->fname) 893 NDFREE(&nd, NDF_ONLY_PNBUF); 894 if (imgp->opened) 895 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 896 if (error != 0) 897 vput(imgp->vp); 898 else 899 VOP_UNLOCK(imgp->vp, 0); 900 } 901 902 if (imgp->object != NULL) 903 vm_object_deallocate(imgp->object); 904 905 free(imgp->freepath, M_TEMP); 906 907 if (error == 0) { 908 PROC_LOCK(p); 909 td->td_dbgflags |= TDB_EXEC; 910 PROC_UNLOCK(p); 911 912 /* 913 * Stop the process here if its stop event mask has 914 * the S_EXEC bit set. 915 */ 916 STOPEVENT(p, S_EXEC, 0); 917 goto done2; 918 } 919 920 exec_fail: 921 /* we're done here, clear P_INEXEC */ 922 PROC_LOCK(p); 923 p->p_flag &= ~P_INEXEC; 924 PROC_UNLOCK(p); 925 926 SDT_PROBE1(proc, , , exec__failure, error); 927 928 done2: 929 #ifdef MAC 930 mac_execve_exit(imgp); 931 mac_execve_interpreter_exit(interpvplabel); 932 #endif 933 exec_free_args(args); 934 935 if (error && imgp->vmspace_destroyed) { 936 /* sorry, no more process anymore. exit gracefully */ 937 exit1(td, 0, SIGABRT); 938 /* NOT REACHED */ 939 } 940 941 #ifdef KTRACE 942 if (error == 0) 943 ktrprocctor(p); 944 #endif 945 946 return (error); 947 } 948 949 int 950 exec_map_first_page(imgp) 951 struct image_params *imgp; 952 { 953 int rv, i, after, initial_pagein; 954 vm_page_t ma[VM_INITIAL_PAGEIN]; 955 vm_object_t object; 956 957 if (imgp->firstpage != NULL) 958 exec_unmap_first_page(imgp); 959 960 object = imgp->vp->v_object; 961 if (object == NULL) 962 return (EACCES); 963 VM_OBJECT_WLOCK(object); 964 #if VM_NRESERVLEVEL > 0 965 vm_object_color(object, 0); 966 #endif 967 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL); 968 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 969 if (!vm_pager_has_page(object, 0, NULL, &after)) { 970 vm_page_lock(ma[0]); 971 vm_page_free(ma[0]); 972 vm_page_unlock(ma[0]); 973 vm_page_xunbusy(ma[0]); 974 VM_OBJECT_WUNLOCK(object); 975 return (EIO); 976 } 977 initial_pagein = min(after, VM_INITIAL_PAGEIN); 978 KASSERT(initial_pagein <= object->size, 979 ("%s: initial_pagein %d object->size %ju", 980 __func__, initial_pagein, (uintmax_t )object->size)); 981 for (i = 1; i < initial_pagein; i++) { 982 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 983 if (ma[i]->valid) 984 break; 985 if (vm_page_tryxbusy(ma[i])) 986 break; 987 } else { 988 ma[i] = vm_page_alloc(object, i, 989 VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); 990 if (ma[i] == NULL) 991 break; 992 } 993 } 994 initial_pagein = i; 995 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 996 if (rv != VM_PAGER_OK) { 997 for (i = 0; i < initial_pagein; i++) { 998 vm_page_lock(ma[i]); 999 vm_page_free(ma[i]); 1000 vm_page_unlock(ma[i]); 1001 vm_page_xunbusy(ma[i]); 1002 } 1003 VM_OBJECT_WUNLOCK(object); 1004 return (EIO); 1005 } 1006 for (i = 1; i < initial_pagein; i++) 1007 vm_page_readahead_finish(ma[i]); 1008 } 1009 vm_page_xunbusy(ma[0]); 1010 vm_page_lock(ma[0]); 1011 vm_page_hold(ma[0]); 1012 vm_page_activate(ma[0]); 1013 vm_page_unlock(ma[0]); 1014 VM_OBJECT_WUNLOCK(object); 1015 1016 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1017 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1018 1019 return (0); 1020 } 1021 1022 void 1023 exec_unmap_first_page(imgp) 1024 struct image_params *imgp; 1025 { 1026 vm_page_t m; 1027 1028 if (imgp->firstpage != NULL) { 1029 m = sf_buf_page(imgp->firstpage); 1030 sf_buf_free(imgp->firstpage); 1031 imgp->firstpage = NULL; 1032 vm_page_lock(m); 1033 vm_page_unhold(m); 1034 vm_page_unlock(m); 1035 } 1036 } 1037 1038 /* 1039 * Destroy old address space, and allocate a new stack 1040 * The new stack is only SGROWSIZ large because it is grown 1041 * automatically in trap.c. 1042 */ 1043 int 1044 exec_new_vmspace(imgp, sv) 1045 struct image_params *imgp; 1046 struct sysentvec *sv; 1047 { 1048 int error; 1049 struct proc *p = imgp->proc; 1050 struct vmspace *vmspace = p->p_vmspace; 1051 vm_object_t obj; 1052 struct rlimit rlim_stack; 1053 vm_offset_t sv_minuser, stack_addr; 1054 vm_map_t map; 1055 u_long ssiz; 1056 1057 imgp->vmspace_destroyed = 1; 1058 imgp->sysent = sv; 1059 1060 /* May be called with Giant held */ 1061 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1062 1063 /* 1064 * Blow away entire process VM, if address space not shared, 1065 * otherwise, create a new VM space so that other threads are 1066 * not disrupted 1067 */ 1068 map = &vmspace->vm_map; 1069 if (map_at_zero) 1070 sv_minuser = sv->sv_minuser; 1071 else 1072 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1073 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1074 vm_map_max(map) == sv->sv_maxuser) { 1075 shmexit(vmspace); 1076 pmap_remove_pages(vmspace_pmap(vmspace)); 1077 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1078 } else { 1079 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1080 if (error) 1081 return (error); 1082 vmspace = p->p_vmspace; 1083 map = &vmspace->vm_map; 1084 } 1085 1086 /* Map a shared page */ 1087 obj = sv->sv_shared_page_obj; 1088 if (obj != NULL) { 1089 vm_object_reference(obj); 1090 error = vm_map_fixed(map, obj, 0, 1091 sv->sv_shared_page_base, sv->sv_shared_page_len, 1092 VM_PROT_READ | VM_PROT_EXECUTE, 1093 VM_PROT_READ | VM_PROT_EXECUTE, 1094 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1095 if (error) { 1096 vm_object_deallocate(obj); 1097 return (error); 1098 } 1099 } 1100 1101 /* Allocate a new stack */ 1102 if (imgp->stack_sz != 0) { 1103 ssiz = trunc_page(imgp->stack_sz); 1104 PROC_LOCK(p); 1105 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1106 PROC_UNLOCK(p); 1107 if (ssiz > rlim_stack.rlim_max) 1108 ssiz = rlim_stack.rlim_max; 1109 if (ssiz > rlim_stack.rlim_cur) { 1110 rlim_stack.rlim_cur = ssiz; 1111 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1112 } 1113 } else if (sv->sv_maxssiz != NULL) { 1114 ssiz = *sv->sv_maxssiz; 1115 } else { 1116 ssiz = maxssiz; 1117 } 1118 stack_addr = sv->sv_usrstack - ssiz; 1119 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1120 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1121 sv->sv_stackprot, 1122 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1123 if (error) 1124 return (error); 1125 1126 /* 1127 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1128 * are still used to enforce the stack rlimit on the process stack. 1129 */ 1130 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1131 vmspace->vm_maxsaddr = (char *)stack_addr; 1132 1133 return (0); 1134 } 1135 1136 /* 1137 * Copy out argument and environment strings from the old process address 1138 * space into the temporary string buffer. 1139 */ 1140 int 1141 exec_copyin_args(struct image_args *args, char *fname, 1142 enum uio_seg segflg, char **argv, char **envv) 1143 { 1144 u_long argp, envp; 1145 int error; 1146 size_t length; 1147 1148 bzero(args, sizeof(*args)); 1149 if (argv == NULL) 1150 return (EFAULT); 1151 1152 /* 1153 * Allocate demand-paged memory for the file name, argument, and 1154 * environment strings. 1155 */ 1156 error = exec_alloc_args(args); 1157 if (error != 0) 1158 return (error); 1159 1160 /* 1161 * Copy the file name. 1162 */ 1163 if (fname != NULL) { 1164 args->fname = args->buf; 1165 error = (segflg == UIO_SYSSPACE) ? 1166 copystr(fname, args->fname, PATH_MAX, &length) : 1167 copyinstr(fname, args->fname, PATH_MAX, &length); 1168 if (error != 0) 1169 goto err_exit; 1170 } else 1171 length = 0; 1172 1173 args->begin_argv = args->buf + length; 1174 args->endp = args->begin_argv; 1175 args->stringspace = ARG_MAX; 1176 1177 /* 1178 * extract arguments first 1179 */ 1180 for (;;) { 1181 error = fueword(argv++, &argp); 1182 if (error == -1) { 1183 error = EFAULT; 1184 goto err_exit; 1185 } 1186 if (argp == 0) 1187 break; 1188 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1189 args->stringspace, &length); 1190 if (error != 0) { 1191 if (error == ENAMETOOLONG) 1192 error = E2BIG; 1193 goto err_exit; 1194 } 1195 args->stringspace -= length; 1196 args->endp += length; 1197 args->argc++; 1198 } 1199 1200 args->begin_envv = args->endp; 1201 1202 /* 1203 * extract environment strings 1204 */ 1205 if (envv) { 1206 for (;;) { 1207 error = fueword(envv++, &envp); 1208 if (error == -1) { 1209 error = EFAULT; 1210 goto err_exit; 1211 } 1212 if (envp == 0) 1213 break; 1214 error = copyinstr((void *)(uintptr_t)envp, 1215 args->endp, args->stringspace, &length); 1216 if (error != 0) { 1217 if (error == ENAMETOOLONG) 1218 error = E2BIG; 1219 goto err_exit; 1220 } 1221 args->stringspace -= length; 1222 args->endp += length; 1223 args->envc++; 1224 } 1225 } 1226 1227 return (0); 1228 1229 err_exit: 1230 exec_free_args(args); 1231 return (error); 1232 } 1233 1234 int 1235 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1236 const void *data, size_t datalen, const int *fds, size_t fdslen) 1237 { 1238 struct filedesc *ofdp; 1239 const char *p; 1240 int *kfds; 1241 int error; 1242 1243 memset(args, '\0', sizeof(*args)); 1244 ofdp = td->td_proc->p_fd; 1245 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1246 return (E2BIG); 1247 error = exec_alloc_args(args); 1248 if (error != 0) 1249 return (error); 1250 1251 args->begin_argv = args->buf; 1252 args->stringspace = ARG_MAX; 1253 1254 if (datalen > 0) { 1255 /* 1256 * Argument buffer has been provided. Copy it into the 1257 * kernel as a single string and add a terminating null 1258 * byte. 1259 */ 1260 error = copyin(data, args->begin_argv, datalen); 1261 if (error != 0) 1262 goto err_exit; 1263 args->begin_argv[datalen] = '\0'; 1264 args->endp = args->begin_argv + datalen + 1; 1265 args->stringspace -= datalen + 1; 1266 1267 /* 1268 * Traditional argument counting. Count the number of 1269 * null bytes. 1270 */ 1271 for (p = args->begin_argv; p < args->endp; ++p) 1272 if (*p == '\0') 1273 ++args->argc; 1274 } else { 1275 /* No argument buffer provided. */ 1276 args->endp = args->begin_argv; 1277 } 1278 /* There are no environment variables. */ 1279 args->begin_envv = args->endp; 1280 1281 /* Create new file descriptor table. */ 1282 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1283 error = copyin(fds, kfds, fdslen * sizeof(int)); 1284 if (error != 0) { 1285 free(kfds, M_TEMP); 1286 goto err_exit; 1287 } 1288 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1289 free(kfds, M_TEMP); 1290 if (error != 0) 1291 goto err_exit; 1292 1293 return (0); 1294 err_exit: 1295 exec_free_args(args); 1296 return (error); 1297 } 1298 1299 /* 1300 * Allocate temporary demand-paged, zero-filled memory for the file name, 1301 * argument, and environment strings. Returns zero if the allocation succeeds 1302 * and ENOMEM otherwise. 1303 */ 1304 int 1305 exec_alloc_args(struct image_args *args) 1306 { 1307 1308 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1309 return (args->buf != NULL ? 0 : ENOMEM); 1310 } 1311 1312 void 1313 exec_free_args(struct image_args *args) 1314 { 1315 1316 if (args->buf != NULL) { 1317 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1318 PATH_MAX + ARG_MAX); 1319 args->buf = NULL; 1320 } 1321 if (args->fname_buf != NULL) { 1322 free(args->fname_buf, M_TEMP); 1323 args->fname_buf = NULL; 1324 } 1325 if (args->fdp != NULL) 1326 fdescfree_remapped(args->fdp); 1327 } 1328 1329 /* 1330 * Copy strings out to the new process address space, constructing new arg 1331 * and env vector tables. Return a pointer to the base so that it can be used 1332 * as the initial stack pointer. 1333 */ 1334 register_t * 1335 exec_copyout_strings(imgp) 1336 struct image_params *imgp; 1337 { 1338 int argc, envc; 1339 char **vectp; 1340 char *stringp; 1341 uintptr_t destp; 1342 register_t *stack_base; 1343 struct ps_strings *arginfo; 1344 struct proc *p; 1345 size_t execpath_len; 1346 int szsigcode, szps; 1347 char canary[sizeof(long) * 8]; 1348 1349 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1350 /* 1351 * Calculate string base and vector table pointers. 1352 * Also deal with signal trampoline code for this exec type. 1353 */ 1354 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1355 execpath_len = strlen(imgp->execpath) + 1; 1356 else 1357 execpath_len = 0; 1358 p = imgp->proc; 1359 szsigcode = 0; 1360 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1361 if (p->p_sysent->sv_sigcode_base == 0) { 1362 if (p->p_sysent->sv_szsigcode != NULL) 1363 szsigcode = *(p->p_sysent->sv_szsigcode); 1364 } 1365 destp = (uintptr_t)arginfo; 1366 1367 /* 1368 * install sigcode 1369 */ 1370 if (szsigcode != 0) { 1371 destp -= szsigcode; 1372 destp = rounddown2(destp, sizeof(void *)); 1373 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1374 } 1375 1376 /* 1377 * Copy the image path for the rtld. 1378 */ 1379 if (execpath_len != 0) { 1380 destp -= execpath_len; 1381 imgp->execpathp = destp; 1382 copyout(imgp->execpath, (void *)destp, execpath_len); 1383 } 1384 1385 /* 1386 * Prepare the canary for SSP. 1387 */ 1388 arc4rand(canary, sizeof(canary), 0); 1389 destp -= sizeof(canary); 1390 imgp->canary = destp; 1391 copyout(canary, (void *)destp, sizeof(canary)); 1392 imgp->canarylen = sizeof(canary); 1393 1394 /* 1395 * Prepare the pagesizes array. 1396 */ 1397 destp -= szps; 1398 destp = rounddown2(destp, sizeof(void *)); 1399 imgp->pagesizes = destp; 1400 copyout(pagesizes, (void *)destp, szps); 1401 imgp->pagesizeslen = szps; 1402 1403 destp -= ARG_MAX - imgp->args->stringspace; 1404 destp = rounddown2(destp, sizeof(void *)); 1405 1406 /* 1407 * If we have a valid auxargs ptr, prepare some room 1408 * on the stack. 1409 */ 1410 if (imgp->auxargs) { 1411 /* 1412 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1413 * lower compatibility. 1414 */ 1415 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1416 (AT_COUNT * 2); 1417 /* 1418 * The '+ 2' is for the null pointers at the end of each of 1419 * the arg and env vector sets,and imgp->auxarg_size is room 1420 * for argument of Runtime loader. 1421 */ 1422 vectp = (char **)(destp - (imgp->args->argc + 1423 imgp->args->envc + 2 + imgp->auxarg_size) 1424 * sizeof(char *)); 1425 } else { 1426 /* 1427 * The '+ 2' is for the null pointers at the end of each of 1428 * the arg and env vector sets 1429 */ 1430 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1431 + 2) * sizeof(char *)); 1432 } 1433 1434 /* 1435 * vectp also becomes our initial stack base 1436 */ 1437 stack_base = (register_t *)vectp; 1438 1439 stringp = imgp->args->begin_argv; 1440 argc = imgp->args->argc; 1441 envc = imgp->args->envc; 1442 1443 /* 1444 * Copy out strings - arguments and environment. 1445 */ 1446 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1447 1448 /* 1449 * Fill in "ps_strings" struct for ps, w, etc. 1450 */ 1451 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1452 suword32(&arginfo->ps_nargvstr, argc); 1453 1454 /* 1455 * Fill in argument portion of vector table. 1456 */ 1457 for (; argc > 0; --argc) { 1458 suword(vectp++, (long)(intptr_t)destp); 1459 while (*stringp++ != 0) 1460 destp++; 1461 destp++; 1462 } 1463 1464 /* a null vector table pointer separates the argp's from the envp's */ 1465 suword(vectp++, 0); 1466 1467 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1468 suword32(&arginfo->ps_nenvstr, envc); 1469 1470 /* 1471 * Fill in environment portion of vector table. 1472 */ 1473 for (; envc > 0; --envc) { 1474 suword(vectp++, (long)(intptr_t)destp); 1475 while (*stringp++ != 0) 1476 destp++; 1477 destp++; 1478 } 1479 1480 /* end of vector table is a null pointer */ 1481 suword(vectp, 0); 1482 1483 return (stack_base); 1484 } 1485 1486 /* 1487 * Check permissions of file to execute. 1488 * Called with imgp->vp locked. 1489 * Return 0 for success or error code on failure. 1490 */ 1491 int 1492 exec_check_permissions(imgp) 1493 struct image_params *imgp; 1494 { 1495 struct vnode *vp = imgp->vp; 1496 struct vattr *attr = imgp->attr; 1497 struct thread *td; 1498 int error, writecount; 1499 1500 td = curthread; 1501 1502 /* Get file attributes */ 1503 error = VOP_GETATTR(vp, attr, td->td_ucred); 1504 if (error) 1505 return (error); 1506 1507 #ifdef MAC 1508 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1509 if (error) 1510 return (error); 1511 #endif 1512 1513 /* 1514 * 1) Check if file execution is disabled for the filesystem that 1515 * this file resides on. 1516 * 2) Ensure that at least one execute bit is on. Otherwise, a 1517 * privileged user will always succeed, and we don't want this 1518 * to happen unless the file really is executable. 1519 * 3) Ensure that the file is a regular file. 1520 */ 1521 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1522 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1523 (attr->va_type != VREG)) 1524 return (EACCES); 1525 1526 /* 1527 * Zero length files can't be exec'd 1528 */ 1529 if (attr->va_size == 0) 1530 return (ENOEXEC); 1531 1532 /* 1533 * Check for execute permission to file based on current credentials. 1534 */ 1535 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1536 if (error) 1537 return (error); 1538 1539 /* 1540 * Check number of open-for-writes on the file and deny execution 1541 * if there are any. 1542 */ 1543 error = VOP_GET_WRITECOUNT(vp, &writecount); 1544 if (error != 0) 1545 return (error); 1546 if (writecount != 0) 1547 return (ETXTBSY); 1548 1549 /* 1550 * Call filesystem specific open routine (which does nothing in the 1551 * general case). 1552 */ 1553 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1554 if (error == 0) 1555 imgp->opened = 1; 1556 return (error); 1557 } 1558 1559 /* 1560 * Exec handler registration 1561 */ 1562 int 1563 exec_register(execsw_arg) 1564 const struct execsw *execsw_arg; 1565 { 1566 const struct execsw **es, **xs, **newexecsw; 1567 int count = 2; /* New slot and trailing NULL */ 1568 1569 if (execsw) 1570 for (es = execsw; *es; es++) 1571 count++; 1572 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1573 if (newexecsw == NULL) 1574 return (ENOMEM); 1575 xs = newexecsw; 1576 if (execsw) 1577 for (es = execsw; *es; es++) 1578 *xs++ = *es; 1579 *xs++ = execsw_arg; 1580 *xs = NULL; 1581 if (execsw) 1582 free(execsw, M_TEMP); 1583 execsw = newexecsw; 1584 return (0); 1585 } 1586 1587 int 1588 exec_unregister(execsw_arg) 1589 const struct execsw *execsw_arg; 1590 { 1591 const struct execsw **es, **xs, **newexecsw; 1592 int count = 1; 1593 1594 if (execsw == NULL) 1595 panic("unregister with no handlers left?\n"); 1596 1597 for (es = execsw; *es; es++) { 1598 if (*es == execsw_arg) 1599 break; 1600 } 1601 if (*es == NULL) 1602 return (ENOENT); 1603 for (es = execsw; *es; es++) 1604 if (*es != execsw_arg) 1605 count++; 1606 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1607 if (newexecsw == NULL) 1608 return (ENOMEM); 1609 xs = newexecsw; 1610 for (es = execsw; *es; es++) 1611 if (*es != execsw_arg) 1612 *xs++ = *es; 1613 *xs = NULL; 1614 if (execsw) 1615 free(execsw, M_TEMP); 1616 execsw = newexecsw; 1617 return (0); 1618 } 1619