Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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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: releng/11.1/sys/kern/kern_exec.c 320867 2017-07-10 07:12:59Z kib $"); 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/ptrace.h> 57 #include <sys/namei.h> 58 #include <sys/resourcevar.h> 59 #include <sys/rwlock.h> 60 #include <sys/sched.h> 61 #include <sys/sdt.h> 62 #include <sys/sf_buf.h> 63 #include <sys/syscallsubr.h> 64 #include <sys/sysent.h> 65 #include <sys/shm.h> 66 #include <sys/sysctl.h> 67 #include <sys/vnode.h> 68 #include <sys/stat.h> 69 #ifdef KTRACE 70 #include <sys/ktrace.h> 71 #endif 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_page.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_kern.h> 79 #include <vm/vm_extern.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_pager.h> 82 83 #ifdef HWPMC_HOOKS 84 #include <sys/pmckern.h> 85 #endif 86 87 #include <machine/reg.h> 88 89 #include <security/audit/audit.h> 90 #include <security/mac/mac_framework.h> 91 92 #ifdef KDTRACE_HOOKS 93 #include <sys/dtrace_bsd.h> 94 dtrace_execexit_func_t dtrace_fasttrap_exec; 95 #endif 96 97 SDT_PROVIDER_DECLARE(proc); 98 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 99 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 100 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 101 102 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 103 104 int coredump_pack_fileinfo = 1; 105 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 106 &coredump_pack_fileinfo, 0, 107 "Enable file path packing in 'procstat -f' coredump notes"); 108 109 int coredump_pack_vmmapinfo = 1; 110 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 111 &coredump_pack_vmmapinfo, 0, 112 "Enable file path packing in 'procstat -v' coredump notes"); 113 114 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 115 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 116 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 117 static int do_execve(struct thread *td, struct image_args *args, 118 struct mac *mac_p); 119 120 /* XXX This should be vm_size_t. */ 121 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 122 CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", ""); 123 124 /* XXX This should be vm_size_t. */ 125 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 126 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", ""); 127 128 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 129 NULL, 0, sysctl_kern_stackprot, "I", ""); 130 131 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 132 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 133 &ps_arg_cache_limit, 0, ""); 134 135 static int disallow_high_osrel; 136 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 137 &disallow_high_osrel, 0, 138 "Disallow execution of binaries built for higher version of the world"); 139 140 static int map_at_zero = 0; 141 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 142 "Permit processes to map an object at virtual address 0."); 143 144 static int 145 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 146 { 147 struct proc *p; 148 int error; 149 150 p = curproc; 151 #ifdef SCTL_MASK32 152 if (req->flags & SCTL_MASK32) { 153 unsigned int val; 154 val = (unsigned int)p->p_sysent->sv_psstrings; 155 error = SYSCTL_OUT(req, &val, sizeof(val)); 156 } else 157 #endif 158 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 159 sizeof(p->p_sysent->sv_psstrings)); 160 return error; 161 } 162 163 static int 164 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 165 { 166 struct proc *p; 167 int error; 168 169 p = curproc; 170 #ifdef SCTL_MASK32 171 if (req->flags & SCTL_MASK32) { 172 unsigned int val; 173 val = (unsigned int)p->p_sysent->sv_usrstack; 174 error = SYSCTL_OUT(req, &val, sizeof(val)); 175 } else 176 #endif 177 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 178 sizeof(p->p_sysent->sv_usrstack)); 179 return error; 180 } 181 182 static int 183 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 184 { 185 struct proc *p; 186 187 p = curproc; 188 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 189 sizeof(p->p_sysent->sv_stackprot))); 190 } 191 192 /* 193 * Each of the items is a pointer to a `const struct execsw', hence the 194 * double pointer here. 195 */ 196 static const struct execsw **execsw; 197 198 #ifndef _SYS_SYSPROTO_H_ 199 struct execve_args { 200 char *fname; 201 char **argv; 202 char **envv; 203 }; 204 #endif 205 206 int 207 sys_execve(struct thread *td, struct execve_args *uap) 208 { 209 struct image_args args; 210 struct vmspace *oldvmspace; 211 int error; 212 213 error = pre_execve(td, &oldvmspace); 214 if (error != 0) 215 return (error); 216 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 217 uap->argv, uap->envv); 218 if (error == 0) 219 error = kern_execve(td, &args, NULL); 220 post_execve(td, error, oldvmspace); 221 return (error); 222 } 223 224 #ifndef _SYS_SYSPROTO_H_ 225 struct fexecve_args { 226 int fd; 227 char **argv; 228 char **envv; 229 } 230 #endif 231 int 232 sys_fexecve(struct thread *td, struct fexecve_args *uap) 233 { 234 struct image_args args; 235 struct vmspace *oldvmspace; 236 int error; 237 238 error = pre_execve(td, &oldvmspace); 239 if (error != 0) 240 return (error); 241 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 242 uap->argv, uap->envv); 243 if (error == 0) { 244 args.fd = uap->fd; 245 error = kern_execve(td, &args, NULL); 246 } 247 post_execve(td, error, oldvmspace); 248 return (error); 249 } 250 251 #ifndef _SYS_SYSPROTO_H_ 252 struct __mac_execve_args { 253 char *fname; 254 char **argv; 255 char **envv; 256 struct mac *mac_p; 257 }; 258 #endif 259 260 int 261 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 262 { 263 #ifdef MAC 264 struct image_args args; 265 struct vmspace *oldvmspace; 266 int error; 267 268 error = pre_execve(td, &oldvmspace); 269 if (error != 0) 270 return (error); 271 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 272 uap->argv, uap->envv); 273 if (error == 0) 274 error = kern_execve(td, &args, uap->mac_p); 275 post_execve(td, error, oldvmspace); 276 return (error); 277 #else 278 return (ENOSYS); 279 #endif 280 } 281 282 int 283 pre_execve(struct thread *td, struct vmspace **oldvmspace) 284 { 285 struct proc *p; 286 int error; 287 288 KASSERT(td == curthread, ("non-current thread %p", td)); 289 error = 0; 290 p = td->td_proc; 291 if ((p->p_flag & P_HADTHREADS) != 0) { 292 PROC_LOCK(p); 293 if (thread_single(p, SINGLE_BOUNDARY) != 0) 294 error = ERESTART; 295 PROC_UNLOCK(p); 296 } 297 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 298 ("nested execve")); 299 *oldvmspace = p->p_vmspace; 300 return (error); 301 } 302 303 void 304 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 305 { 306 struct proc *p; 307 308 KASSERT(td == curthread, ("non-current thread %p", td)); 309 p = td->td_proc; 310 if ((p->p_flag & P_HADTHREADS) != 0) { 311 PROC_LOCK(p); 312 /* 313 * If success, we upgrade to SINGLE_EXIT state to 314 * force other threads to suicide. 315 */ 316 if (error == 0) 317 thread_single(p, SINGLE_EXIT); 318 else 319 thread_single_end(p, SINGLE_BOUNDARY); 320 PROC_UNLOCK(p); 321 } 322 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 323 KASSERT(p->p_vmspace != oldvmspace, 324 ("oldvmspace still used")); 325 vmspace_free(oldvmspace); 326 td->td_pflags &= ~TDP_EXECVMSPC; 327 } 328 } 329 330 /* 331 * XXX: kern_execve has the astonishing property of not always returning to 332 * the caller. If sufficiently bad things happen during the call to 333 * do_execve(), it can end up calling exit1(); as a result, callers must 334 * avoid doing anything which they might need to undo (e.g., allocating 335 * memory). 336 */ 337 int 338 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 339 { 340 341 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 342 args->begin_envv - args->begin_argv); 343 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 344 args->endp - args->begin_envv); 345 return (do_execve(td, args, mac_p)); 346 } 347 348 /* 349 * In-kernel implementation of execve(). All arguments are assumed to be 350 * userspace pointers from the passed thread. 351 */ 352 static int 353 do_execve(td, args, mac_p) 354 struct thread *td; 355 struct image_args *args; 356 struct mac *mac_p; 357 { 358 struct proc *p = td->td_proc; 359 struct nameidata nd; 360 struct ucred *oldcred; 361 struct uidinfo *euip = NULL; 362 register_t *stack_base; 363 int error, i; 364 struct image_params image_params, *imgp; 365 struct vattr attr; 366 int (*img_first)(struct image_params *); 367 struct pargs *oldargs = NULL, *newargs = NULL; 368 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 369 #ifdef KTRACE 370 struct vnode *tracevp = NULL; 371 struct ucred *tracecred = NULL; 372 #endif 373 struct vnode *oldtextvp = NULL, *newtextvp; 374 cap_rights_t rights; 375 int credential_changing; 376 int textset; 377 #ifdef MAC 378 struct label *interpvplabel = NULL; 379 int will_transition; 380 #endif 381 #ifdef HWPMC_HOOKS 382 struct pmckern_procexec pe; 383 #endif 384 static const char fexecv_proc_title[] = "(fexecv)"; 385 386 imgp = &image_params; 387 388 /* 389 * Lock the process and set the P_INEXEC flag to indicate that 390 * it should be left alone until we're done here. This is 391 * necessary to avoid race conditions - e.g. in ptrace() - 392 * that might allow a local user to illicitly obtain elevated 393 * privileges. 394 */ 395 PROC_LOCK(p); 396 KASSERT((p->p_flag & P_INEXEC) == 0, 397 ("%s(): process already has P_INEXEC flag", __func__)); 398 p->p_flag |= P_INEXEC; 399 PROC_UNLOCK(p); 400 401 /* 402 * Initialize part of the common data 403 */ 404 bzero(imgp, sizeof(*imgp)); 405 imgp->proc = p; 406 imgp->attr = &attr; 407 imgp->args = args; 408 oldcred = p->p_ucred; 409 410 #ifdef MAC 411 error = mac_execve_enter(imgp, mac_p); 412 if (error) 413 goto exec_fail; 414 #endif 415 416 /* 417 * Translate the file name. namei() returns a vnode pointer 418 * in ni_vp among other things. 419 * 420 * XXXAUDIT: It would be desirable to also audit the name of the 421 * interpreter if this is an interpreted binary. 422 */ 423 if (args->fname != NULL) { 424 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 425 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 426 } 427 428 SDT_PROBE1(proc, , , exec, args->fname); 429 430 interpret: 431 if (args->fname != NULL) { 432 #ifdef CAPABILITY_MODE 433 /* 434 * While capability mode can't reach this point via direct 435 * path arguments to execve(), we also don't allow 436 * interpreters to be used in capability mode (for now). 437 * Catch indirect lookups and return a permissions error. 438 */ 439 if (IN_CAPABILITY_MODE(td)) { 440 error = ECAPMODE; 441 goto exec_fail; 442 } 443 #endif 444 error = namei(&nd); 445 if (error) 446 goto exec_fail; 447 448 newtextvp = nd.ni_vp; 449 imgp->vp = newtextvp; 450 } else { 451 AUDIT_ARG_FD(args->fd); 452 /* 453 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 454 */ 455 error = fgetvp_exec(td, args->fd, 456 cap_rights_init(&rights, CAP_FEXECVE), &newtextvp); 457 if (error) 458 goto exec_fail; 459 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY); 460 AUDIT_ARG_VNODE1(newtextvp); 461 imgp->vp = newtextvp; 462 } 463 464 /* 465 * Check file permissions (also 'opens' file) 466 */ 467 error = exec_check_permissions(imgp); 468 if (error) 469 goto exec_fail_dealloc; 470 471 imgp->object = imgp->vp->v_object; 472 if (imgp->object != NULL) 473 vm_object_reference(imgp->object); 474 475 /* 476 * Set VV_TEXT now so no one can write to the executable while we're 477 * activating it. 478 * 479 * Remember if this was set before and unset it in case this is not 480 * actually an executable image. 481 */ 482 textset = VOP_IS_TEXT(imgp->vp); 483 VOP_SET_TEXT(imgp->vp); 484 485 error = exec_map_first_page(imgp); 486 if (error) 487 goto exec_fail_dealloc; 488 489 imgp->proc->p_osrel = 0; 490 491 /* 492 * Implement image setuid/setgid. 493 * 494 * Determine new credentials before attempting image activators 495 * so that it can be used by process_exec handlers to determine 496 * credential/setid changes. 497 * 498 * Don't honor setuid/setgid if the filesystem prohibits it or if 499 * the process is being traced. 500 * 501 * We disable setuid/setgid/etc in capability mode on the basis 502 * that most setugid applications are not written with that 503 * environment in mind, and will therefore almost certainly operate 504 * incorrectly. In principle there's no reason that setugid 505 * applications might not be useful in capability mode, so we may want 506 * to reconsider this conservative design choice in the future. 507 * 508 * XXXMAC: For the time being, use NOSUID to also prohibit 509 * transitions on the file system. 510 */ 511 credential_changing = 0; 512 credential_changing |= (attr.va_mode & S_ISUID) && 513 oldcred->cr_uid != attr.va_uid; 514 credential_changing |= (attr.va_mode & S_ISGID) && 515 oldcred->cr_gid != attr.va_gid; 516 #ifdef MAC 517 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 518 interpvplabel, imgp); 519 credential_changing |= will_transition; 520 #endif 521 522 if (credential_changing && 523 #ifdef CAPABILITY_MODE 524 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 525 #endif 526 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 527 (p->p_flag & P_TRACED) == 0) { 528 imgp->credential_setid = true; 529 VOP_UNLOCK(imgp->vp, 0); 530 imgp->newcred = crdup(oldcred); 531 if (attr.va_mode & S_ISUID) { 532 euip = uifind(attr.va_uid); 533 change_euid(imgp->newcred, euip); 534 } 535 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 536 if (attr.va_mode & S_ISGID) 537 change_egid(imgp->newcred, attr.va_gid); 538 /* 539 * Implement correct POSIX saved-id behavior. 540 * 541 * XXXMAC: Note that the current logic will save the 542 * uid and gid if a MAC domain transition occurs, even 543 * though maybe it shouldn't. 544 */ 545 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 546 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 547 } else { 548 /* 549 * Implement correct POSIX saved-id behavior. 550 * 551 * XXX: It's not clear that the existing behavior is 552 * POSIX-compliant. A number of sources indicate that the 553 * saved uid/gid should only be updated if the new ruid is 554 * not equal to the old ruid, or the new euid is not equal 555 * to the old euid and the new euid is not equal to the old 556 * ruid. The FreeBSD code always updates the saved uid/gid. 557 * Also, this code uses the new (replaced) euid and egid as 558 * the source, which may or may not be the right ones to use. 559 */ 560 if (oldcred->cr_svuid != oldcred->cr_uid || 561 oldcred->cr_svgid != oldcred->cr_gid) { 562 VOP_UNLOCK(imgp->vp, 0); 563 imgp->newcred = crdup(oldcred); 564 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 565 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 566 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 567 } 568 } 569 /* The new credentials are installed into the process later. */ 570 571 /* 572 * Do the best to calculate the full path to the image file. 573 */ 574 if (args->fname != NULL && args->fname[0] == '/') 575 imgp->execpath = args->fname; 576 else { 577 VOP_UNLOCK(imgp->vp, 0); 578 if (vn_fullpath(td, imgp->vp, &imgp->execpath, 579 &imgp->freepath) != 0) 580 imgp->execpath = args->fname; 581 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 582 } 583 584 /* 585 * If the current process has a special image activator it 586 * wants to try first, call it. For example, emulating shell 587 * scripts differently. 588 */ 589 error = -1; 590 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 591 error = img_first(imgp); 592 593 /* 594 * Loop through the list of image activators, calling each one. 595 * An activator returns -1 if there is no match, 0 on success, 596 * and an error otherwise. 597 */ 598 for (i = 0; error == -1 && execsw[i]; ++i) { 599 if (execsw[i]->ex_imgact == NULL || 600 execsw[i]->ex_imgact == img_first) { 601 continue; 602 } 603 error = (*execsw[i]->ex_imgact)(imgp); 604 } 605 606 if (error) { 607 if (error == -1) { 608 if (textset == 0) 609 VOP_UNSET_TEXT(imgp->vp); 610 error = ENOEXEC; 611 } 612 goto exec_fail_dealloc; 613 } 614 615 /* 616 * Special interpreter operation, cleanup and loop up to try to 617 * activate the interpreter. 618 */ 619 if (imgp->interpreted) { 620 exec_unmap_first_page(imgp); 621 /* 622 * VV_TEXT needs to be unset for scripts. There is a short 623 * period before we determine that something is a script where 624 * VV_TEXT will be set. The vnode lock is held over this 625 * entire period so nothing should illegitimately be blocked. 626 */ 627 VOP_UNSET_TEXT(imgp->vp); 628 /* free name buffer and old vnode */ 629 if (args->fname != NULL) 630 NDFREE(&nd, NDF_ONLY_PNBUF); 631 #ifdef MAC 632 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 633 #endif 634 if (imgp->opened) { 635 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 636 imgp->opened = 0; 637 } 638 vput(newtextvp); 639 vm_object_deallocate(imgp->object); 640 imgp->object = NULL; 641 imgp->credential_setid = false; 642 if (imgp->newcred != NULL) { 643 crfree(imgp->newcred); 644 imgp->newcred = NULL; 645 } 646 imgp->execpath = NULL; 647 free(imgp->freepath, M_TEMP); 648 imgp->freepath = NULL; 649 /* set new name to that of the interpreter */ 650 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 651 UIO_SYSSPACE, imgp->interpreter_name, td); 652 args->fname = imgp->interpreter_name; 653 goto interpret; 654 } 655 656 /* 657 * NB: We unlock the vnode here because it is believed that none 658 * of the sv_copyout_strings/sv_fixup operations require the vnode. 659 */ 660 VOP_UNLOCK(imgp->vp, 0); 661 662 if (disallow_high_osrel && 663 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 664 error = ENOEXEC; 665 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 666 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 667 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 668 goto exec_fail_dealloc; 669 } 670 671 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 672 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 673 sys_cap_enter(td, NULL); 674 675 /* 676 * Copy out strings (args and env) and initialize stack base 677 */ 678 if (p->p_sysent->sv_copyout_strings) 679 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 680 else 681 stack_base = exec_copyout_strings(imgp); 682 683 /* 684 * If custom stack fixup routine present for this process 685 * let it do the stack setup. 686 * Else stuff argument count as first item on stack 687 */ 688 if (p->p_sysent->sv_fixup != NULL) 689 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 690 else 691 suword(--stack_base, imgp->args->argc); 692 693 if (args->fdp != NULL) { 694 /* Install a brand new file descriptor table. */ 695 fdinstall_remapped(td, args->fdp); 696 args->fdp = NULL; 697 } else { 698 /* 699 * Keep on using the existing file descriptor table. For 700 * security and other reasons, the file descriptor table 701 * cannot be shared after an exec. 702 */ 703 fdunshare(td); 704 /* close files on exec */ 705 fdcloseexec(td); 706 } 707 708 /* 709 * Malloc things before we need locks. 710 */ 711 i = imgp->args->begin_envv - imgp->args->begin_argv; 712 /* Cache arguments if they fit inside our allowance */ 713 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 714 newargs = pargs_alloc(i); 715 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 716 } 717 718 /* 719 * For security and other reasons, signal handlers cannot 720 * be shared after an exec. The new process gets a copy of the old 721 * handlers. In execsigs(), the new process will have its signals 722 * reset. 723 */ 724 if (sigacts_shared(p->p_sigacts)) { 725 oldsigacts = p->p_sigacts; 726 newsigacts = sigacts_alloc(); 727 sigacts_copy(newsigacts, oldsigacts); 728 } 729 730 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 731 732 PROC_LOCK(p); 733 if (oldsigacts) 734 p->p_sigacts = newsigacts; 735 /* Stop profiling */ 736 stopprofclock(p); 737 738 /* reset caught signals */ 739 execsigs(p); 740 741 /* name this process - nameiexec(p, ndp) */ 742 bzero(p->p_comm, sizeof(p->p_comm)); 743 if (args->fname) 744 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 745 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 746 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 747 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 748 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 749 #ifdef KTR 750 sched_clear_tdname(td); 751 #endif 752 753 /* 754 * mark as execed, wakeup the process that vforked (if any) and tell 755 * it that it now has its own resources back 756 */ 757 p->p_flag |= P_EXEC; 758 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 759 p->p_flag2 &= ~P2_NOTRACE; 760 if (p->p_flag & P_PPWAIT) { 761 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 762 cv_broadcast(&p->p_pwait); 763 /* STOPs are no longer ignored, arrange for AST */ 764 signotify(td); 765 } 766 767 /* 768 * Implement image setuid/setgid installation. 769 */ 770 if (imgp->credential_setid) { 771 /* 772 * Turn off syscall tracing for set-id programs, except for 773 * root. Record any set-id flags first to make sure that 774 * we do not regain any tracing during a possible block. 775 */ 776 setsugid(p); 777 778 #ifdef KTRACE 779 if (p->p_tracecred != NULL && 780 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 781 ktrprocexec(p, &tracecred, &tracevp); 782 #endif 783 /* 784 * Close any file descriptors 0..2 that reference procfs, 785 * then make sure file descriptors 0..2 are in use. 786 * 787 * Both fdsetugidsafety() and fdcheckstd() may call functions 788 * taking sleepable locks, so temporarily drop our locks. 789 */ 790 PROC_UNLOCK(p); 791 VOP_UNLOCK(imgp->vp, 0); 792 fdsetugidsafety(td); 793 error = fdcheckstd(td); 794 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 795 if (error != 0) 796 goto exec_fail_dealloc; 797 PROC_LOCK(p); 798 #ifdef MAC 799 if (will_transition) { 800 mac_vnode_execve_transition(oldcred, imgp->newcred, 801 imgp->vp, interpvplabel, imgp); 802 } 803 #endif 804 } else { 805 if (oldcred->cr_uid == oldcred->cr_ruid && 806 oldcred->cr_gid == oldcred->cr_rgid) 807 p->p_flag &= ~P_SUGID; 808 } 809 /* 810 * Set the new credentials. 811 */ 812 if (imgp->newcred != NULL) { 813 proc_set_cred(p, imgp->newcred); 814 crfree(oldcred); 815 oldcred = NULL; 816 } 817 818 /* 819 * Store the vp for use in procfs. This vnode was referenced by namei 820 * or fgetvp_exec. 821 */ 822 oldtextvp = p->p_textvp; 823 p->p_textvp = newtextvp; 824 825 #ifdef KDTRACE_HOOKS 826 /* 827 * Tell the DTrace fasttrap provider about the exec if it 828 * has declared an interest. 829 */ 830 if (dtrace_fasttrap_exec) 831 dtrace_fasttrap_exec(p); 832 #endif 833 834 /* 835 * Notify others that we exec'd, and clear the P_INEXEC flag 836 * as we're now a bona fide freshly-execed process. 837 */ 838 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 839 p->p_flag &= ~P_INEXEC; 840 841 /* clear "fork but no exec" flag, as we _are_ execing */ 842 p->p_acflag &= ~AFORK; 843 844 /* 845 * Free any previous argument cache and replace it with 846 * the new argument cache, if any. 847 */ 848 oldargs = p->p_args; 849 p->p_args = newargs; 850 newargs = NULL; 851 852 #ifdef HWPMC_HOOKS 853 /* 854 * Check if system-wide sampling is in effect or if the 855 * current process is using PMCs. If so, do exec() time 856 * processing. This processing needs to happen AFTER the 857 * P_INEXEC flag is cleared. 858 * 859 * The proc lock needs to be released before taking the PMC 860 * SX. 861 */ 862 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 863 PROC_UNLOCK(p); 864 VOP_UNLOCK(imgp->vp, 0); 865 pe.pm_credentialschanged = credential_changing; 866 pe.pm_entryaddr = imgp->entry_addr; 867 868 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 869 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 870 } else 871 PROC_UNLOCK(p); 872 #else /* !HWPMC_HOOKS */ 873 PROC_UNLOCK(p); 874 #endif 875 876 /* Set values passed into the program in registers. */ 877 if (p->p_sysent->sv_setregs) 878 (*p->p_sysent->sv_setregs)(td, imgp, 879 (u_long)(uintptr_t)stack_base); 880 else 881 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 882 883 vfs_mark_atime(imgp->vp, td->td_ucred); 884 885 SDT_PROBE1(proc, , , exec__success, args->fname); 886 887 exec_fail_dealloc: 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 if (p->p_ptevents & PTRACE_EXEC) 910 td->td_dbgflags |= TDB_EXEC; 911 PROC_UNLOCK(p); 912 913 /* 914 * Stop the process here if its stop event mask has 915 * the S_EXEC bit set. 916 */ 917 STOPEVENT(p, S_EXEC, 0); 918 } else { 919 exec_fail: 920 /* we're done here, clear P_INEXEC */ 921 PROC_LOCK(p); 922 p->p_flag &= ~P_INEXEC; 923 PROC_UNLOCK(p); 924 925 SDT_PROBE1(proc, , , exec__failure, error); 926 } 927 928 if (imgp->newcred != NULL && oldcred != NULL) 929 crfree(imgp->newcred); 930 931 #ifdef MAC 932 mac_execve_exit(imgp); 933 mac_execve_interpreter_exit(interpvplabel); 934 #endif 935 exec_free_args(args); 936 937 /* 938 * Handle deferred decrement of ref counts. 939 */ 940 if (oldtextvp != NULL) 941 vrele(oldtextvp); 942 #ifdef KTRACE 943 if (tracevp != NULL) 944 vrele(tracevp); 945 if (tracecred != NULL) 946 crfree(tracecred); 947 #endif 948 pargs_drop(oldargs); 949 pargs_drop(newargs); 950 if (oldsigacts != NULL) 951 sigacts_free(oldsigacts); 952 if (euip != NULL) 953 uifree(euip); 954 955 if (error && imgp->vmspace_destroyed) { 956 /* sorry, no more process anymore. exit gracefully */ 957 exit1(td, 0, SIGABRT); 958 /* NOT REACHED */ 959 } 960 961 #ifdef KTRACE 962 if (error == 0) 963 ktrprocctor(p); 964 #endif 965 966 return (error); 967 } 968 969 int 970 exec_map_first_page(imgp) 971 struct image_params *imgp; 972 { 973 int rv, i, after, initial_pagein; 974 vm_page_t ma[VM_INITIAL_PAGEIN]; 975 vm_object_t object; 976 977 if (imgp->firstpage != NULL) 978 exec_unmap_first_page(imgp); 979 980 object = imgp->vp->v_object; 981 if (object == NULL) 982 return (EACCES); 983 VM_OBJECT_WLOCK(object); 984 #if VM_NRESERVLEVEL > 0 985 vm_object_color(object, 0); 986 #endif 987 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 988 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 989 vm_page_xbusy(ma[0]); 990 if (!vm_pager_has_page(object, 0, NULL, &after)) { 991 vm_page_lock(ma[0]); 992 vm_page_free(ma[0]); 993 vm_page_unlock(ma[0]); 994 VM_OBJECT_WUNLOCK(object); 995 return (EIO); 996 } 997 initial_pagein = min(after, VM_INITIAL_PAGEIN); 998 KASSERT(initial_pagein <= object->size, 999 ("%s: initial_pagein %d object->size %ju", 1000 __func__, initial_pagein, (uintmax_t )object->size)); 1001 for (i = 1; i < initial_pagein; i++) { 1002 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 1003 if (ma[i]->valid) 1004 break; 1005 if (vm_page_tryxbusy(ma[i])) 1006 break; 1007 } else { 1008 ma[i] = vm_page_alloc(object, i, 1009 VM_ALLOC_NORMAL); 1010 if (ma[i] == NULL) 1011 break; 1012 } 1013 } 1014 initial_pagein = i; 1015 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 1016 if (rv != VM_PAGER_OK) { 1017 for (i = 0; i < initial_pagein; i++) { 1018 vm_page_lock(ma[i]); 1019 vm_page_free(ma[i]); 1020 vm_page_unlock(ma[i]); 1021 } 1022 VM_OBJECT_WUNLOCK(object); 1023 return (EIO); 1024 } 1025 vm_page_xunbusy(ma[0]); 1026 for (i = 1; i < initial_pagein; i++) 1027 vm_page_readahead_finish(ma[i]); 1028 } 1029 vm_page_lock(ma[0]); 1030 vm_page_hold(ma[0]); 1031 vm_page_activate(ma[0]); 1032 vm_page_unlock(ma[0]); 1033 VM_OBJECT_WUNLOCK(object); 1034 1035 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1036 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1037 1038 return (0); 1039 } 1040 1041 void 1042 exec_unmap_first_page(imgp) 1043 struct image_params *imgp; 1044 { 1045 vm_page_t m; 1046 1047 if (imgp->firstpage != NULL) { 1048 m = sf_buf_page(imgp->firstpage); 1049 sf_buf_free(imgp->firstpage); 1050 imgp->firstpage = NULL; 1051 vm_page_lock(m); 1052 vm_page_unhold(m); 1053 vm_page_unlock(m); 1054 } 1055 } 1056 1057 /* 1058 * Destroy old address space, and allocate a new stack. 1059 * The new stack is only sgrowsiz large because it is grown 1060 * automatically on a page fault. 1061 */ 1062 int 1063 exec_new_vmspace(imgp, sv) 1064 struct image_params *imgp; 1065 struct sysentvec *sv; 1066 { 1067 int error; 1068 struct proc *p = imgp->proc; 1069 struct vmspace *vmspace = p->p_vmspace; 1070 vm_object_t obj; 1071 struct rlimit rlim_stack; 1072 vm_offset_t sv_minuser, stack_addr; 1073 vm_map_t map; 1074 u_long ssiz; 1075 1076 imgp->vmspace_destroyed = 1; 1077 imgp->sysent = sv; 1078 1079 /* May be called with Giant held */ 1080 EVENTHANDLER_INVOKE(process_exec, p, imgp); 1081 1082 /* 1083 * Blow away entire process VM, if address space not shared, 1084 * otherwise, create a new VM space so that other threads are 1085 * not disrupted 1086 */ 1087 map = &vmspace->vm_map; 1088 if (map_at_zero) 1089 sv_minuser = sv->sv_minuser; 1090 else 1091 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1092 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1093 vm_map_max(map) == sv->sv_maxuser) { 1094 shmexit(vmspace); 1095 pmap_remove_pages(vmspace_pmap(vmspace)); 1096 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1097 } else { 1098 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1099 if (error) 1100 return (error); 1101 vmspace = p->p_vmspace; 1102 map = &vmspace->vm_map; 1103 } 1104 1105 /* Map a shared page */ 1106 obj = sv->sv_shared_page_obj; 1107 if (obj != NULL) { 1108 vm_object_reference(obj); 1109 error = vm_map_fixed(map, obj, 0, 1110 sv->sv_shared_page_base, sv->sv_shared_page_len, 1111 VM_PROT_READ | VM_PROT_EXECUTE, 1112 VM_PROT_READ | VM_PROT_EXECUTE, 1113 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1114 if (error != KERN_SUCCESS) { 1115 vm_object_deallocate(obj); 1116 return (vm_mmap_to_errno(error)); 1117 } 1118 } 1119 1120 /* Allocate a new stack */ 1121 if (imgp->stack_sz != 0) { 1122 ssiz = trunc_page(imgp->stack_sz); 1123 PROC_LOCK(p); 1124 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1125 PROC_UNLOCK(p); 1126 if (ssiz > rlim_stack.rlim_max) 1127 ssiz = rlim_stack.rlim_max; 1128 if (ssiz > rlim_stack.rlim_cur) { 1129 rlim_stack.rlim_cur = ssiz; 1130 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1131 } 1132 } else if (sv->sv_maxssiz != NULL) { 1133 ssiz = *sv->sv_maxssiz; 1134 } else { 1135 ssiz = maxssiz; 1136 } 1137 stack_addr = sv->sv_usrstack - ssiz; 1138 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1139 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1140 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1141 if (error != KERN_SUCCESS) 1142 return (vm_mmap_to_errno(error)); 1143 1144 /* 1145 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1146 * are still used to enforce the stack rlimit on the process stack. 1147 */ 1148 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1149 vmspace->vm_maxsaddr = (char *)stack_addr; 1150 1151 return (0); 1152 } 1153 1154 /* 1155 * Copy out argument and environment strings from the old process address 1156 * space into the temporary string buffer. 1157 */ 1158 int 1159 exec_copyin_args(struct image_args *args, char *fname, 1160 enum uio_seg segflg, char **argv, char **envv) 1161 { 1162 u_long argp, envp; 1163 int error; 1164 size_t length; 1165 1166 bzero(args, sizeof(*args)); 1167 if (argv == NULL) 1168 return (EFAULT); 1169 1170 /* 1171 * Allocate demand-paged memory for the file name, argument, and 1172 * environment strings. 1173 */ 1174 error = exec_alloc_args(args); 1175 if (error != 0) 1176 return (error); 1177 1178 /* 1179 * Copy the file name. 1180 */ 1181 if (fname != NULL) { 1182 args->fname = args->buf; 1183 error = (segflg == UIO_SYSSPACE) ? 1184 copystr(fname, args->fname, PATH_MAX, &length) : 1185 copyinstr(fname, args->fname, PATH_MAX, &length); 1186 if (error != 0) 1187 goto err_exit; 1188 } else 1189 length = 0; 1190 1191 args->begin_argv = args->buf + length; 1192 args->endp = args->begin_argv; 1193 args->stringspace = ARG_MAX; 1194 1195 /* 1196 * extract arguments first 1197 */ 1198 for (;;) { 1199 error = fueword(argv++, &argp); 1200 if (error == -1) { 1201 error = EFAULT; 1202 goto err_exit; 1203 } 1204 if (argp == 0) 1205 break; 1206 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1207 args->stringspace, &length); 1208 if (error != 0) { 1209 if (error == ENAMETOOLONG) 1210 error = E2BIG; 1211 goto err_exit; 1212 } 1213 args->stringspace -= length; 1214 args->endp += length; 1215 args->argc++; 1216 } 1217 1218 args->begin_envv = args->endp; 1219 1220 /* 1221 * extract environment strings 1222 */ 1223 if (envv) { 1224 for (;;) { 1225 error = fueword(envv++, &envp); 1226 if (error == -1) { 1227 error = EFAULT; 1228 goto err_exit; 1229 } 1230 if (envp == 0) 1231 break; 1232 error = copyinstr((void *)(uintptr_t)envp, 1233 args->endp, args->stringspace, &length); 1234 if (error != 0) { 1235 if (error == ENAMETOOLONG) 1236 error = E2BIG; 1237 goto err_exit; 1238 } 1239 args->stringspace -= length; 1240 args->endp += length; 1241 args->envc++; 1242 } 1243 } 1244 1245 return (0); 1246 1247 err_exit: 1248 exec_free_args(args); 1249 return (error); 1250 } 1251 1252 int 1253 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1254 const void *data, size_t datalen, const int *fds, size_t fdslen) 1255 { 1256 struct filedesc *ofdp; 1257 const char *p; 1258 int *kfds; 1259 int error; 1260 1261 memset(args, '\0', sizeof(*args)); 1262 ofdp = td->td_proc->p_fd; 1263 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1264 return (E2BIG); 1265 error = exec_alloc_args(args); 1266 if (error != 0) 1267 return (error); 1268 1269 args->begin_argv = args->buf; 1270 args->stringspace = ARG_MAX; 1271 1272 if (datalen > 0) { 1273 /* 1274 * Argument buffer has been provided. Copy it into the 1275 * kernel as a single string and add a terminating null 1276 * byte. 1277 */ 1278 error = copyin(data, args->begin_argv, datalen); 1279 if (error != 0) 1280 goto err_exit; 1281 args->begin_argv[datalen] = '\0'; 1282 args->endp = args->begin_argv + datalen + 1; 1283 args->stringspace -= datalen + 1; 1284 1285 /* 1286 * Traditional argument counting. Count the number of 1287 * null bytes. 1288 */ 1289 for (p = args->begin_argv; p < args->endp; ++p) 1290 if (*p == '\0') 1291 ++args->argc; 1292 } else { 1293 /* No argument buffer provided. */ 1294 args->endp = args->begin_argv; 1295 } 1296 /* There are no environment variables. */ 1297 args->begin_envv = args->endp; 1298 1299 /* Create new file descriptor table. */ 1300 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1301 error = copyin(fds, kfds, fdslen * sizeof(int)); 1302 if (error != 0) { 1303 free(kfds, M_TEMP); 1304 goto err_exit; 1305 } 1306 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1307 free(kfds, M_TEMP); 1308 if (error != 0) 1309 goto err_exit; 1310 1311 return (0); 1312 err_exit: 1313 exec_free_args(args); 1314 return (error); 1315 } 1316 1317 /* 1318 * Allocate temporary demand-paged, zero-filled memory for the file name, 1319 * argument, and environment strings. Returns zero if the allocation succeeds 1320 * and ENOMEM otherwise. 1321 */ 1322 int 1323 exec_alloc_args(struct image_args *args) 1324 { 1325 1326 args->buf = (char *)kmap_alloc_wait(exec_map, PATH_MAX + ARG_MAX); 1327 return (args->buf != NULL ? 0 : ENOMEM); 1328 } 1329 1330 void 1331 exec_free_args(struct image_args *args) 1332 { 1333 1334 if (args->buf != NULL) { 1335 kmap_free_wakeup(exec_map, (vm_offset_t)args->buf, 1336 PATH_MAX + ARG_MAX); 1337 args->buf = NULL; 1338 } 1339 if (args->fname_buf != NULL) { 1340 free(args->fname_buf, M_TEMP); 1341 args->fname_buf = NULL; 1342 } 1343 if (args->fdp != NULL) 1344 fdescfree_remapped(args->fdp); 1345 } 1346 1347 /* 1348 * Copy strings out to the new process address space, constructing new arg 1349 * and env vector tables. Return a pointer to the base so that it can be used 1350 * as the initial stack pointer. 1351 */ 1352 register_t * 1353 exec_copyout_strings(imgp) 1354 struct image_params *imgp; 1355 { 1356 int argc, envc; 1357 char **vectp; 1358 char *stringp; 1359 uintptr_t destp; 1360 register_t *stack_base; 1361 struct ps_strings *arginfo; 1362 struct proc *p; 1363 size_t execpath_len; 1364 int szsigcode, szps; 1365 char canary[sizeof(long) * 8]; 1366 1367 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1368 /* 1369 * Calculate string base and vector table pointers. 1370 * Also deal with signal trampoline code for this exec type. 1371 */ 1372 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1373 execpath_len = strlen(imgp->execpath) + 1; 1374 else 1375 execpath_len = 0; 1376 p = imgp->proc; 1377 szsigcode = 0; 1378 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1379 if (p->p_sysent->sv_sigcode_base == 0) { 1380 if (p->p_sysent->sv_szsigcode != NULL) 1381 szsigcode = *(p->p_sysent->sv_szsigcode); 1382 } 1383 destp = (uintptr_t)arginfo; 1384 1385 /* 1386 * install sigcode 1387 */ 1388 if (szsigcode != 0) { 1389 destp -= szsigcode; 1390 destp = rounddown2(destp, sizeof(void *)); 1391 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1392 } 1393 1394 /* 1395 * Copy the image path for the rtld. 1396 */ 1397 if (execpath_len != 0) { 1398 destp -= execpath_len; 1399 imgp->execpathp = destp; 1400 copyout(imgp->execpath, (void *)destp, execpath_len); 1401 } 1402 1403 /* 1404 * Prepare the canary for SSP. 1405 */ 1406 arc4rand(canary, sizeof(canary), 0); 1407 destp -= sizeof(canary); 1408 imgp->canary = destp; 1409 copyout(canary, (void *)destp, sizeof(canary)); 1410 imgp->canarylen = sizeof(canary); 1411 1412 /* 1413 * Prepare the pagesizes array. 1414 */ 1415 destp -= szps; 1416 destp = rounddown2(destp, sizeof(void *)); 1417 imgp->pagesizes = destp; 1418 copyout(pagesizes, (void *)destp, szps); 1419 imgp->pagesizeslen = szps; 1420 1421 destp -= ARG_MAX - imgp->args->stringspace; 1422 destp = rounddown2(destp, sizeof(void *)); 1423 1424 /* 1425 * If we have a valid auxargs ptr, prepare some room 1426 * on the stack. 1427 */ 1428 if (imgp->auxargs) { 1429 /* 1430 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1431 * lower compatibility. 1432 */ 1433 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1434 (AT_COUNT * 2); 1435 /* 1436 * The '+ 2' is for the null pointers at the end of each of 1437 * the arg and env vector sets,and imgp->auxarg_size is room 1438 * for argument of Runtime loader. 1439 */ 1440 vectp = (char **)(destp - (imgp->args->argc + 1441 imgp->args->envc + 2 + imgp->auxarg_size) 1442 * sizeof(char *)); 1443 } else { 1444 /* 1445 * The '+ 2' is for the null pointers at the end of each of 1446 * the arg and env vector sets 1447 */ 1448 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1449 + 2) * sizeof(char *)); 1450 } 1451 1452 /* 1453 * vectp also becomes our initial stack base 1454 */ 1455 stack_base = (register_t *)vectp; 1456 1457 stringp = imgp->args->begin_argv; 1458 argc = imgp->args->argc; 1459 envc = imgp->args->envc; 1460 1461 /* 1462 * Copy out strings - arguments and environment. 1463 */ 1464 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1465 1466 /* 1467 * Fill in "ps_strings" struct for ps, w, etc. 1468 */ 1469 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1470 suword32(&arginfo->ps_nargvstr, argc); 1471 1472 /* 1473 * Fill in argument portion of vector table. 1474 */ 1475 for (; argc > 0; --argc) { 1476 suword(vectp++, (long)(intptr_t)destp); 1477 while (*stringp++ != 0) 1478 destp++; 1479 destp++; 1480 } 1481 1482 /* a null vector table pointer separates the argp's from the envp's */ 1483 suword(vectp++, 0); 1484 1485 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1486 suword32(&arginfo->ps_nenvstr, envc); 1487 1488 /* 1489 * Fill in environment portion of vector table. 1490 */ 1491 for (; envc > 0; --envc) { 1492 suword(vectp++, (long)(intptr_t)destp); 1493 while (*stringp++ != 0) 1494 destp++; 1495 destp++; 1496 } 1497 1498 /* end of vector table is a null pointer */ 1499 suword(vectp, 0); 1500 1501 return (stack_base); 1502 } 1503 1504 /* 1505 * Check permissions of file to execute. 1506 * Called with imgp->vp locked. 1507 * Return 0 for success or error code on failure. 1508 */ 1509 int 1510 exec_check_permissions(imgp) 1511 struct image_params *imgp; 1512 { 1513 struct vnode *vp = imgp->vp; 1514 struct vattr *attr = imgp->attr; 1515 struct thread *td; 1516 int error, writecount; 1517 1518 td = curthread; 1519 1520 /* Get file attributes */ 1521 error = VOP_GETATTR(vp, attr, td->td_ucred); 1522 if (error) 1523 return (error); 1524 1525 #ifdef MAC 1526 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1527 if (error) 1528 return (error); 1529 #endif 1530 1531 /* 1532 * 1) Check if file execution is disabled for the filesystem that 1533 * this file resides on. 1534 * 2) Ensure that at least one execute bit is on. Otherwise, a 1535 * privileged user will always succeed, and we don't want this 1536 * to happen unless the file really is executable. 1537 * 3) Ensure that the file is a regular file. 1538 */ 1539 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1540 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1541 (attr->va_type != VREG)) 1542 return (EACCES); 1543 1544 /* 1545 * Zero length files can't be exec'd 1546 */ 1547 if (attr->va_size == 0) 1548 return (ENOEXEC); 1549 1550 /* 1551 * Check for execute permission to file based on current credentials. 1552 */ 1553 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1554 if (error) 1555 return (error); 1556 1557 /* 1558 * Check number of open-for-writes on the file and deny execution 1559 * if there are any. 1560 */ 1561 error = VOP_GET_WRITECOUNT(vp, &writecount); 1562 if (error != 0) 1563 return (error); 1564 if (writecount != 0) 1565 return (ETXTBSY); 1566 1567 /* 1568 * Call filesystem specific open routine (which does nothing in the 1569 * general case). 1570 */ 1571 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1572 if (error == 0) 1573 imgp->opened = 1; 1574 return (error); 1575 } 1576 1577 /* 1578 * Exec handler registration 1579 */ 1580 int 1581 exec_register(execsw_arg) 1582 const struct execsw *execsw_arg; 1583 { 1584 const struct execsw **es, **xs, **newexecsw; 1585 int count = 2; /* New slot and trailing NULL */ 1586 1587 if (execsw) 1588 for (es = execsw; *es; es++) 1589 count++; 1590 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1591 xs = newexecsw; 1592 if (execsw) 1593 for (es = execsw; *es; es++) 1594 *xs++ = *es; 1595 *xs++ = execsw_arg; 1596 *xs = NULL; 1597 if (execsw) 1598 free(execsw, M_TEMP); 1599 execsw = newexecsw; 1600 return (0); 1601 } 1602 1603 int 1604 exec_unregister(execsw_arg) 1605 const struct execsw *execsw_arg; 1606 { 1607 const struct execsw **es, **xs, **newexecsw; 1608 int count = 1; 1609 1610 if (execsw == NULL) 1611 panic("unregister with no handlers left?\n"); 1612 1613 for (es = execsw; *es; es++) { 1614 if (*es == execsw_arg) 1615 break; 1616 } 1617 if (*es == NULL) 1618 return (ENOENT); 1619 for (es = execsw; *es; es++) 1620 if (*es != execsw_arg) 1621 count++; 1622 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1623 xs = newexecsw; 1624 for (es = execsw; *es; es++) 1625 if (*es != execsw_arg) 1626 *xs++ = *es; 1627 *xs = NULL; 1628 if (execsw) 1629 free(execsw, M_TEMP); 1630 execsw = newexecsw; 1631 return (0); 1632 }
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