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 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 1993, David Greenman 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include "opt_capsicum.h" 33 #include "opt_hwpmc_hooks.h" 34 #include "opt_ktrace.h" 35 #include "opt_vm.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/acct.h> 40 #include <sys/capsicum.h> 41 #include <sys/eventhandler.h> 42 #include <sys/exec.h> 43 #include <sys/fcntl.h> 44 #include <sys/filedesc.h> 45 #include <sys/imgact.h> 46 #include <sys/imgact_elf.h> 47 #include <sys/kernel.h> 48 #include <sys/lock.h> 49 #include <sys/malloc.h> 50 #include <sys/mman.h> 51 #include <sys/mount.h> 52 #include <sys/mutex.h> 53 #include <sys/namei.h> 54 #include <sys/pioctl.h> 55 #include <sys/priv.h> 56 #include <sys/proc.h> 57 #include <sys/ptrace.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/shm.h> 64 #include <sys/signalvar.h> 65 #include <sys/smp.h> 66 #include <sys/stat.h> 67 #include <sys/syscallsubr.h> 68 #include <sys/sysctl.h> 69 #include <sys/sysent.h> 70 #include <sys/sysproto.h> 71 #include <sys/timers.h> 72 #include <sys/umtx.h> 73 #include <sys/vnode.h> 74 #include <sys/wait.h> 75 #ifdef KTRACE 76 #include <sys/ktrace.h> 77 #endif 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <vm/pmap.h> 82 #include <vm/vm_page.h> 83 #include <vm/vm_map.h> 84 #include <vm/vm_kern.h> 85 #include <vm/vm_extern.h> 86 #include <vm/vm_object.h> 87 #include <vm/vm_pager.h> 88 89 #ifdef HWPMC_HOOKS 90 #include <sys/pmckern.h> 91 #endif 92 93 #include <machine/reg.h> 94 95 #include <security/audit/audit.h> 96 #include <security/mac/mac_framework.h> 97 98 #ifdef KDTRACE_HOOKS 99 #include <sys/dtrace_bsd.h> 100 dtrace_execexit_func_t dtrace_fasttrap_exec; 101 #endif 102 103 SDT_PROVIDER_DECLARE(proc); 104 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 105 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 106 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 107 108 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 109 110 int coredump_pack_fileinfo = 1; 111 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 112 &coredump_pack_fileinfo, 0, 113 "Enable file path packing in 'procstat -f' coredump notes"); 114 115 int coredump_pack_vmmapinfo = 1; 116 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 117 &coredump_pack_vmmapinfo, 0, 118 "Enable file path packing in 'procstat -v' coredump notes"); 119 120 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 121 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 122 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 123 static int do_execve(struct thread *td, struct image_args *args, 124 struct mac *mac_p, struct vmspace *oldvmspace); 125 126 /* XXX This should be vm_size_t. */ 127 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 128 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", ""); 129 130 /* XXX This should be vm_size_t. */ 131 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 132 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", ""); 133 134 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 135 NULL, 0, sysctl_kern_stackprot, "I", ""); 136 137 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 138 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 139 &ps_arg_cache_limit, 0, ""); 140 141 static int disallow_high_osrel; 142 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 143 &disallow_high_osrel, 0, 144 "Disallow execution of binaries built for higher version of the world"); 145 146 static int map_at_zero = 0; 147 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 148 "Permit processes to map an object at virtual address 0."); 149 150 EVENTHANDLER_LIST_DECLARE(process_exec); 151 152 static int 153 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 154 { 155 struct proc *p; 156 int error; 157 158 p = curproc; 159 #ifdef SCTL_MASK32 160 if (req->flags & SCTL_MASK32) { 161 unsigned int val; 162 val = (unsigned int)p->p_sysent->sv_psstrings; 163 error = SYSCTL_OUT(req, &val, sizeof(val)); 164 } else 165 #endif 166 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 167 sizeof(p->p_sysent->sv_psstrings)); 168 return error; 169 } 170 171 static int 172 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 173 { 174 struct proc *p; 175 int error; 176 177 p = curproc; 178 #ifdef SCTL_MASK32 179 if (req->flags & SCTL_MASK32) { 180 unsigned int val; 181 val = (unsigned int)p->p_sysent->sv_usrstack; 182 error = SYSCTL_OUT(req, &val, sizeof(val)); 183 } else 184 #endif 185 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 186 sizeof(p->p_sysent->sv_usrstack)); 187 return error; 188 } 189 190 static int 191 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 192 { 193 struct proc *p; 194 195 p = curproc; 196 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 197 sizeof(p->p_sysent->sv_stackprot))); 198 } 199 200 /* 201 * Each of the items is a pointer to a `const struct execsw', hence the 202 * double pointer here. 203 */ 204 static const struct execsw **execsw; 205 206 #ifndef _SYS_SYSPROTO_H_ 207 struct execve_args { 208 char *fname; 209 char **argv; 210 char **envv; 211 }; 212 #endif 213 214 int 215 sys_execve(struct thread *td, struct execve_args *uap) 216 { 217 struct image_args args; 218 struct vmspace *oldvmspace; 219 int error; 220 221 error = pre_execve(td, &oldvmspace); 222 if (error != 0) 223 return (error); 224 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 225 uap->argv, uap->envv); 226 if (error == 0) 227 error = kern_execve(td, &args, NULL, oldvmspace); 228 post_execve(td, error, oldvmspace); 229 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 230 return (error); 231 } 232 233 #ifndef _SYS_SYSPROTO_H_ 234 struct fexecve_args { 235 int fd; 236 char **argv; 237 char **envv; 238 } 239 #endif 240 int 241 sys_fexecve(struct thread *td, struct fexecve_args *uap) 242 { 243 struct image_args args; 244 struct vmspace *oldvmspace; 245 int error; 246 247 error = pre_execve(td, &oldvmspace); 248 if (error != 0) 249 return (error); 250 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 251 uap->argv, uap->envv); 252 if (error == 0) { 253 args.fd = uap->fd; 254 error = kern_execve(td, &args, NULL, oldvmspace); 255 } 256 post_execve(td, error, oldvmspace); 257 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 258 return (error); 259 } 260 261 #ifndef _SYS_SYSPROTO_H_ 262 struct __mac_execve_args { 263 char *fname; 264 char **argv; 265 char **envv; 266 struct mac *mac_p; 267 }; 268 #endif 269 270 int 271 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 272 { 273 #ifdef MAC 274 struct image_args args; 275 struct vmspace *oldvmspace; 276 int error; 277 278 error = pre_execve(td, &oldvmspace); 279 if (error != 0) 280 return (error); 281 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 282 uap->argv, uap->envv); 283 if (error == 0) 284 error = kern_execve(td, &args, uap->mac_p, oldvmspace); 285 post_execve(td, error, oldvmspace); 286 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 287 return (error); 288 #else 289 return (ENOSYS); 290 #endif 291 } 292 293 int 294 pre_execve(struct thread *td, struct vmspace **oldvmspace) 295 { 296 struct proc *p; 297 int error; 298 299 KASSERT(td == curthread, ("non-current thread %p", td)); 300 error = 0; 301 p = td->td_proc; 302 if ((p->p_flag & P_HADTHREADS) != 0) { 303 PROC_LOCK(p); 304 if (thread_single(p, SINGLE_BOUNDARY) != 0) 305 error = ERESTART; 306 PROC_UNLOCK(p); 307 } 308 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 309 ("nested execve")); 310 *oldvmspace = p->p_vmspace; 311 return (error); 312 } 313 314 void 315 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 316 { 317 struct proc *p; 318 319 KASSERT(td == curthread, ("non-current thread %p", td)); 320 p = td->td_proc; 321 if ((p->p_flag & P_HADTHREADS) != 0) { 322 PROC_LOCK(p); 323 /* 324 * If success, we upgrade to SINGLE_EXIT state to 325 * force other threads to suicide. 326 */ 327 if (error == EJUSTRETURN) 328 thread_single(p, SINGLE_EXIT); 329 else 330 thread_single_end(p, SINGLE_BOUNDARY); 331 PROC_UNLOCK(p); 332 } 333 exec_cleanup(td, oldvmspace); 334 } 335 336 /* 337 * kern_execve() has the astonishing property of not always returning to 338 * the caller. If sufficiently bad things happen during the call to 339 * do_execve(), it can end up calling exit1(); as a result, callers must 340 * avoid doing anything which they might need to undo (e.g., allocating 341 * memory). 342 */ 343 int 344 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 345 struct vmspace *oldvmspace) 346 { 347 348 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 349 args->begin_envv - args->begin_argv); 350 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 351 args->endp - args->begin_envv); 352 353 /* Must have at least one argument. */ 354 if (args->argc == 0) { 355 exec_free_args(args); 356 return (EINVAL); 357 } 358 return (do_execve(td, args, mac_p, oldvmspace)); 359 } 360 361 /* 362 * In-kernel implementation of execve(). All arguments are assumed to be 363 * userspace pointers from the passed thread. 364 */ 365 static int 366 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 367 struct vmspace *oldvmspace) 368 { 369 struct proc *p = td->td_proc; 370 struct nameidata nd; 371 struct ucred *oldcred; 372 struct uidinfo *euip = NULL; 373 register_t *stack_base; 374 struct image_params image_params, *imgp; 375 struct vattr attr; 376 int (*img_first)(struct image_params *); 377 struct pargs *oldargs = NULL, *newargs = NULL; 378 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 379 #ifdef KTRACE 380 struct vnode *tracevp = NULL; 381 struct ucred *tracecred = NULL; 382 #endif 383 struct vnode *oldtextvp = NULL, *newtextvp; 384 int credential_changing; 385 #ifdef MAC 386 struct label *interpvplabel = NULL; 387 int will_transition; 388 #endif 389 #ifdef HWPMC_HOOKS 390 struct pmckern_procexec pe; 391 #endif 392 int error, i, orig_osrel; 393 uint32_t orig_fctl0; 394 static const char fexecv_proc_title[] = "(fexecv)"; 395 396 imgp = &image_params; 397 398 /* 399 * Lock the process and set the P_INEXEC flag to indicate that 400 * it should be left alone until we're done here. This is 401 * necessary to avoid race conditions - e.g. in ptrace() - 402 * that might allow a local user to illicitly obtain elevated 403 * privileges. 404 */ 405 PROC_LOCK(p); 406 KASSERT((p->p_flag & P_INEXEC) == 0, 407 ("%s(): process already has P_INEXEC flag", __func__)); 408 p->p_flag |= P_INEXEC; 409 PROC_UNLOCK(p); 410 411 /* 412 * Initialize part of the common data 413 */ 414 bzero(imgp, sizeof(*imgp)); 415 imgp->proc = p; 416 imgp->attr = &attr; 417 imgp->args = args; 418 oldcred = p->p_ucred; 419 orig_osrel = p->p_osrel; 420 orig_fctl0 = p->p_fctl0; 421 422 #ifdef MAC 423 error = mac_execve_enter(imgp, mac_p); 424 if (error) 425 goto exec_fail; 426 #endif 427 428 /* 429 * Translate the file name. namei() returns a vnode pointer 430 * in ni_vp among other things. 431 * 432 * XXXAUDIT: It would be desirable to also audit the name of the 433 * interpreter if this is an interpreted binary. 434 */ 435 if (args->fname != NULL) { 436 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 437 SAVENAME | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 438 } 439 440 SDT_PROBE1(proc, , , exec, args->fname); 441 442 interpret: 443 if (args->fname != NULL) { 444 #ifdef CAPABILITY_MODE 445 /* 446 * While capability mode can't reach this point via direct 447 * path arguments to execve(), we also don't allow 448 * interpreters to be used in capability mode (for now). 449 * Catch indirect lookups and return a permissions error. 450 */ 451 if (IN_CAPABILITY_MODE(td)) { 452 error = ECAPMODE; 453 goto exec_fail; 454 } 455 #endif 456 error = namei(&nd); 457 if (error) 458 goto exec_fail; 459 460 newtextvp = nd.ni_vp; 461 imgp->vp = newtextvp; 462 } else { 463 AUDIT_ARG_FD(args->fd); 464 /* 465 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 466 */ 467 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp); 468 if (error) 469 goto exec_fail; 470 vn_lock(newtextvp, LK_SHARED | LK_RETRY); 471 AUDIT_ARG_VNODE1(newtextvp); 472 imgp->vp = newtextvp; 473 } 474 475 /* 476 * Check file permissions. Also 'opens' file and sets its vnode to 477 * text mode. 478 */ 479 error = exec_check_permissions(imgp); 480 if (error) 481 goto exec_fail_dealloc; 482 483 imgp->object = imgp->vp->v_object; 484 if (imgp->object != NULL) 485 vm_object_reference(imgp->object); 486 487 error = exec_map_first_page(imgp); 488 if (error) 489 goto exec_fail_dealloc; 490 491 imgp->proc->p_osrel = 0; 492 imgp->proc->p_fctl0 = 0; 493 494 /* 495 * Implement image setuid/setgid. 496 * 497 * Determine new credentials before attempting image activators 498 * so that it can be used by process_exec handlers to determine 499 * credential/setid changes. 500 * 501 * Don't honor setuid/setgid if the filesystem prohibits it or if 502 * the process is being traced. 503 * 504 * We disable setuid/setgid/etc in capability mode on the basis 505 * that most setugid applications are not written with that 506 * environment in mind, and will therefore almost certainly operate 507 * incorrectly. In principle there's no reason that setugid 508 * applications might not be useful in capability mode, so we may want 509 * to reconsider this conservative design choice in the future. 510 * 511 * XXXMAC: For the time being, use NOSUID to also prohibit 512 * transitions on the file system. 513 */ 514 credential_changing = 0; 515 credential_changing |= (attr.va_mode & S_ISUID) && 516 oldcred->cr_uid != attr.va_uid; 517 credential_changing |= (attr.va_mode & S_ISGID) && 518 oldcred->cr_gid != attr.va_gid; 519 #ifdef MAC 520 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 521 interpvplabel, imgp); 522 credential_changing |= will_transition; 523 #endif 524 525 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 526 if (credential_changing) 527 imgp->proc->p_pdeathsig = 0; 528 529 if (credential_changing && 530 #ifdef CAPABILITY_MODE 531 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 532 #endif 533 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 534 (p->p_flag & P_TRACED) == 0) { 535 imgp->credential_setid = true; 536 VOP_UNLOCK(imgp->vp, 0); 537 imgp->newcred = crdup(oldcred); 538 if (attr.va_mode & S_ISUID) { 539 euip = uifind(attr.va_uid); 540 change_euid(imgp->newcred, euip); 541 } 542 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 543 if (attr.va_mode & S_ISGID) 544 change_egid(imgp->newcred, attr.va_gid); 545 /* 546 * Implement correct POSIX saved-id behavior. 547 * 548 * XXXMAC: Note that the current logic will save the 549 * uid and gid if a MAC domain transition occurs, even 550 * though maybe it shouldn't. 551 */ 552 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 553 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 554 } else { 555 /* 556 * Implement correct POSIX saved-id behavior. 557 * 558 * XXX: It's not clear that the existing behavior is 559 * POSIX-compliant. A number of sources indicate that the 560 * saved uid/gid should only be updated if the new ruid is 561 * not equal to the old ruid, or the new euid is not equal 562 * to the old euid and the new euid is not equal to the old 563 * ruid. The FreeBSD code always updates the saved uid/gid. 564 * Also, this code uses the new (replaced) euid and egid as 565 * the source, which may or may not be the right ones to use. 566 */ 567 if (oldcred->cr_svuid != oldcred->cr_uid || 568 oldcred->cr_svgid != oldcred->cr_gid) { 569 VOP_UNLOCK(imgp->vp, 0); 570 imgp->newcred = crdup(oldcred); 571 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 572 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 573 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 574 } 575 } 576 /* The new credentials are installed into the process later. */ 577 578 /* 579 * Do the best to calculate the full path to the image file. 580 */ 581 if (args->fname != NULL && args->fname[0] == '/') 582 imgp->execpath = args->fname; 583 else { 584 VOP_UNLOCK(imgp->vp, 0); 585 if (vn_fullpath(td, imgp->vp, &imgp->execpath, 586 &imgp->freepath) != 0) 587 imgp->execpath = args->fname; 588 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 589 } 590 591 /* 592 * If the current process has a special image activator it 593 * wants to try first, call it. For example, emulating shell 594 * scripts differently. 595 */ 596 error = -1; 597 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 598 error = img_first(imgp); 599 600 /* 601 * Loop through the list of image activators, calling each one. 602 * An activator returns -1 if there is no match, 0 on success, 603 * and an error otherwise. 604 */ 605 for (i = 0; error == -1 && execsw[i]; ++i) { 606 if (execsw[i]->ex_imgact == NULL || 607 execsw[i]->ex_imgact == img_first) { 608 continue; 609 } 610 error = (*execsw[i]->ex_imgact)(imgp); 611 } 612 613 if (error) { 614 if (error == -1) 615 error = ENOEXEC; 616 goto exec_fail_dealloc; 617 } 618 619 /* 620 * Special interpreter operation, cleanup and loop up to try to 621 * activate the interpreter. 622 */ 623 if (imgp->interpreted) { 624 exec_unmap_first_page(imgp); 625 /* 626 * The text reference needs to be removed for scripts. 627 * There is a short period before we determine that 628 * something is a script where text reference is active. 629 * The vnode lock is held over this entire period 630 * so nothing should illegitimately be blocked. 631 */ 632 MPASS(imgp->textset); 633 VOP_UNSET_TEXT_CHECKED(newtextvp); 634 imgp->textset = false; 635 /* free name buffer and old vnode */ 636 if (args->fname != NULL) 637 NDFREE(&nd, NDF_ONLY_PNBUF); 638 #ifdef MAC 639 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 640 #endif 641 if (imgp->opened) { 642 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 643 imgp->opened = 0; 644 } 645 vput(newtextvp); 646 vm_object_deallocate(imgp->object); 647 imgp->object = NULL; 648 imgp->credential_setid = false; 649 if (imgp->newcred != NULL) { 650 crfree(imgp->newcred); 651 imgp->newcred = NULL; 652 } 653 imgp->execpath = NULL; 654 free(imgp->freepath, M_TEMP); 655 imgp->freepath = NULL; 656 /* set new name to that of the interpreter */ 657 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME, 658 UIO_SYSSPACE, imgp->interpreter_name, td); 659 args->fname = imgp->interpreter_name; 660 goto interpret; 661 } 662 663 /* 664 * NB: We unlock the vnode here because it is believed that none 665 * of the sv_copyout_strings/sv_fixup operations require the vnode. 666 */ 667 VOP_UNLOCK(imgp->vp, 0); 668 669 if (disallow_high_osrel && 670 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 671 error = ENOEXEC; 672 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 673 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 674 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 675 goto exec_fail_dealloc; 676 } 677 678 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 679 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 680 sys_cap_enter(td, NULL); 681 682 /* 683 * Copy out strings (args and env) and initialize stack base 684 */ 685 if (p->p_sysent->sv_copyout_strings) 686 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 687 else 688 stack_base = exec_copyout_strings(imgp); 689 690 /* 691 * If custom stack fixup routine present for this process 692 * let it do the stack setup. 693 * Else stuff argument count as first item on stack 694 */ 695 if (p->p_sysent->sv_fixup != NULL) 696 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 697 else 698 error = suword(--stack_base, imgp->args->argc) == 0 ? 699 0 : EFAULT; 700 if (error != 0) { 701 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 702 goto exec_fail_dealloc; 703 } 704 705 if (args->fdp != NULL) { 706 /* Install a brand new file descriptor table. */ 707 fdinstall_remapped(td, args->fdp); 708 args->fdp = NULL; 709 } else { 710 /* 711 * Keep on using the existing file descriptor table. For 712 * security and other reasons, the file descriptor table 713 * cannot be shared after an exec. 714 */ 715 fdunshare(td); 716 /* close files on exec */ 717 fdcloseexec(td); 718 } 719 720 /* 721 * Malloc things before we need locks. 722 */ 723 i = imgp->args->begin_envv - imgp->args->begin_argv; 724 /* Cache arguments if they fit inside our allowance */ 725 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 726 newargs = pargs_alloc(i); 727 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 728 } 729 730 /* 731 * For security and other reasons, signal handlers cannot 732 * be shared after an exec. The new process gets a copy of the old 733 * handlers. In execsigs(), the new process will have its signals 734 * reset. 735 */ 736 if (sigacts_shared(p->p_sigacts)) { 737 oldsigacts = p->p_sigacts; 738 newsigacts = sigacts_alloc(); 739 sigacts_copy(newsigacts, oldsigacts); 740 } 741 742 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 743 744 PROC_LOCK(p); 745 if (oldsigacts) 746 p->p_sigacts = newsigacts; 747 /* Stop profiling */ 748 stopprofclock(p); 749 750 /* reset caught signals */ 751 execsigs(p); 752 753 /* name this process - nameiexec(p, ndp) */ 754 bzero(p->p_comm, sizeof(p->p_comm)); 755 if (args->fname) 756 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 757 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 758 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 759 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 760 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 761 #ifdef KTR 762 sched_clear_tdname(td); 763 #endif 764 765 /* 766 * mark as execed, wakeup the process that vforked (if any) and tell 767 * it that it now has its own resources back 768 */ 769 p->p_flag |= P_EXEC; 770 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 771 p->p_flag2 &= ~P2_NOTRACE; 772 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 773 p->p_flag2 &= ~P2_STKGAP_DISABLE; 774 if (p->p_flag & P_PPWAIT) { 775 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 776 cv_broadcast(&p->p_pwait); 777 /* STOPs are no longer ignored, arrange for AST */ 778 signotify(td); 779 } 780 781 /* 782 * Implement image setuid/setgid installation. 783 */ 784 if (imgp->credential_setid) { 785 /* 786 * Turn off syscall tracing for set-id programs, except for 787 * root. Record any set-id flags first to make sure that 788 * we do not regain any tracing during a possible block. 789 */ 790 setsugid(p); 791 792 #ifdef KTRACE 793 if (p->p_tracecred != NULL && 794 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 795 ktrprocexec(p, &tracecred, &tracevp); 796 #endif 797 /* 798 * Close any file descriptors 0..2 that reference procfs, 799 * then make sure file descriptors 0..2 are in use. 800 * 801 * Both fdsetugidsafety() and fdcheckstd() may call functions 802 * taking sleepable locks, so temporarily drop our locks. 803 */ 804 PROC_UNLOCK(p); 805 VOP_UNLOCK(imgp->vp, 0); 806 fdsetugidsafety(td); 807 error = fdcheckstd(td); 808 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 809 if (error != 0) 810 goto exec_fail_dealloc; 811 PROC_LOCK(p); 812 #ifdef MAC 813 if (will_transition) { 814 mac_vnode_execve_transition(oldcred, imgp->newcred, 815 imgp->vp, interpvplabel, imgp); 816 } 817 #endif 818 } else { 819 if (oldcred->cr_uid == oldcred->cr_ruid && 820 oldcred->cr_gid == oldcred->cr_rgid) 821 p->p_flag &= ~P_SUGID; 822 } 823 /* 824 * Set the new credentials. 825 */ 826 if (imgp->newcred != NULL) { 827 proc_set_cred(p, imgp->newcred); 828 crfree(oldcred); 829 oldcred = NULL; 830 } 831 832 /* 833 * Store the vp for use in procfs. This vnode was referenced by namei 834 * or fgetvp_exec. 835 */ 836 oldtextvp = p->p_textvp; 837 p->p_textvp = newtextvp; 838 839 #ifdef KDTRACE_HOOKS 840 /* 841 * Tell the DTrace fasttrap provider about the exec if it 842 * has declared an interest. 843 */ 844 if (dtrace_fasttrap_exec) 845 dtrace_fasttrap_exec(p); 846 #endif 847 848 /* 849 * Notify others that we exec'd, and clear the P_INEXEC flag 850 * as we're now a bona fide freshly-execed process. 851 */ 852 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 853 p->p_flag &= ~P_INEXEC; 854 855 /* clear "fork but no exec" flag, as we _are_ execing */ 856 p->p_acflag &= ~AFORK; 857 858 /* 859 * Free any previous argument cache and replace it with 860 * the new argument cache, if any. 861 */ 862 oldargs = p->p_args; 863 p->p_args = newargs; 864 newargs = NULL; 865 866 PROC_UNLOCK(p); 867 868 #ifdef HWPMC_HOOKS 869 /* 870 * Check if system-wide sampling is in effect or if the 871 * current process is using PMCs. If so, do exec() time 872 * processing. This processing needs to happen AFTER the 873 * P_INEXEC flag is cleared. 874 */ 875 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 876 VOP_UNLOCK(imgp->vp, 0); 877 pe.pm_credentialschanged = credential_changing; 878 pe.pm_entryaddr = imgp->entry_addr; 879 880 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 881 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 882 } 883 #endif 884 885 /* Set values passed into the program in registers. */ 886 if (p->p_sysent->sv_setregs) 887 (*p->p_sysent->sv_setregs)(td, imgp, 888 (u_long)(uintptr_t)stack_base); 889 else 890 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 891 892 vfs_mark_atime(imgp->vp, td->td_ucred); 893 894 SDT_PROBE1(proc, , , exec__success, args->fname); 895 896 exec_fail_dealloc: 897 if (error != 0) { 898 p->p_osrel = orig_osrel; 899 p->p_fctl0 = orig_fctl0; 900 } 901 902 if (imgp->firstpage != NULL) 903 exec_unmap_first_page(imgp); 904 905 if (imgp->vp != NULL) { 906 if (args->fname) 907 NDFREE(&nd, NDF_ONLY_PNBUF); 908 if (imgp->opened) 909 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 910 if (imgp->textset) 911 VOP_UNSET_TEXT_CHECKED(imgp->vp); 912 if (error != 0) 913 vput(imgp->vp); 914 else 915 VOP_UNLOCK(imgp->vp, 0); 916 } 917 918 if (imgp->object != NULL) 919 vm_object_deallocate(imgp->object); 920 921 free(imgp->freepath, M_TEMP); 922 923 if (error == 0) { 924 if (p->p_ptevents & PTRACE_EXEC) { 925 PROC_LOCK(p); 926 if (p->p_ptevents & PTRACE_EXEC) 927 td->td_dbgflags |= TDB_EXEC; 928 PROC_UNLOCK(p); 929 } 930 931 /* 932 * Stop the process here if its stop event mask has 933 * the S_EXEC bit set. 934 */ 935 STOPEVENT(p, S_EXEC, 0); 936 } else { 937 exec_fail: 938 /* we're done here, clear P_INEXEC */ 939 PROC_LOCK(p); 940 p->p_flag &= ~P_INEXEC; 941 PROC_UNLOCK(p); 942 943 SDT_PROBE1(proc, , , exec__failure, error); 944 } 945 946 if (imgp->newcred != NULL && oldcred != NULL) 947 crfree(imgp->newcred); 948 949 #ifdef MAC 950 mac_execve_exit(imgp); 951 mac_execve_interpreter_exit(interpvplabel); 952 #endif 953 exec_free_args(args); 954 955 /* 956 * Handle deferred decrement of ref counts. 957 */ 958 if (oldtextvp != NULL) 959 vrele(oldtextvp); 960 #ifdef KTRACE 961 if (tracevp != NULL) 962 vrele(tracevp); 963 if (tracecred != NULL) 964 crfree(tracecred); 965 #endif 966 pargs_drop(oldargs); 967 pargs_drop(newargs); 968 if (oldsigacts != NULL) 969 sigacts_free(oldsigacts); 970 if (euip != NULL) 971 uifree(euip); 972 973 if (error && imgp->vmspace_destroyed) { 974 /* sorry, no more process anymore. exit gracefully */ 975 exec_cleanup(td, oldvmspace); 976 exit1(td, 0, SIGABRT); 977 /* NOT REACHED */ 978 } 979 980 #ifdef KTRACE 981 if (error == 0) 982 ktrprocctor(p); 983 #endif 984 985 /* 986 * We don't want cpu_set_syscall_retval() to overwrite any of 987 * the register values put in place by exec_setregs(). 988 * Implementations of cpu_set_syscall_retval() will leave 989 * registers unmodified when returning EJUSTRETURN. 990 */ 991 return (error == 0 ? EJUSTRETURN : error); 992 } 993 994 void 995 exec_cleanup(struct thread *td, struct vmspace *oldvmspace) 996 { 997 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 998 KASSERT(td->td_proc->p_vmspace != oldvmspace, 999 ("oldvmspace still used")); 1000 vmspace_free(oldvmspace); 1001 td->td_pflags &= ~TDP_EXECVMSPC; 1002 } 1003 } 1004 1005 int 1006 exec_map_first_page(struct image_params *imgp) 1007 { 1008 int rv, i, after, initial_pagein; 1009 vm_page_t ma[VM_INITIAL_PAGEIN]; 1010 vm_object_t object; 1011 1012 if (imgp->firstpage != NULL) 1013 exec_unmap_first_page(imgp); 1014 1015 object = imgp->vp->v_object; 1016 if (object == NULL) 1017 return (EACCES); 1018 VM_OBJECT_WLOCK(object); 1019 #if VM_NRESERVLEVEL > 0 1020 vm_object_color(object, 0); 1021 #endif 1022 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 1023 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 1024 vm_page_xbusy(ma[0]); 1025 if (!vm_pager_has_page(object, 0, NULL, &after)) { 1026 vm_page_lock(ma[0]); 1027 if (!vm_page_wired(ma[0])) 1028 vm_page_free(ma[0]); 1029 else 1030 vm_page_xunbusy_maybelocked(ma[0]); 1031 vm_page_unlock(ma[0]); 1032 VM_OBJECT_WUNLOCK(object); 1033 return (EIO); 1034 } 1035 initial_pagein = min(after, VM_INITIAL_PAGEIN); 1036 KASSERT(initial_pagein <= object->size, 1037 ("%s: initial_pagein %d object->size %ju", 1038 __func__, initial_pagein, (uintmax_t )object->size)); 1039 for (i = 1; i < initial_pagein; i++) { 1040 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 1041 if (ma[i]->valid) 1042 break; 1043 if (!vm_page_tryxbusy(ma[i])) 1044 break; 1045 } else { 1046 ma[i] = vm_page_alloc(object, i, 1047 VM_ALLOC_NORMAL); 1048 if (ma[i] == NULL) 1049 break; 1050 } 1051 } 1052 initial_pagein = i; 1053 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 1054 if (rv != VM_PAGER_OK) { 1055 for (i = 0; i < initial_pagein; i++) { 1056 vm_page_lock(ma[i]); 1057 if (!vm_page_wired(ma[i])) 1058 vm_page_free(ma[i]); 1059 else 1060 vm_page_xunbusy_maybelocked(ma[i]); 1061 vm_page_unlock(ma[i]); 1062 } 1063 VM_OBJECT_WUNLOCK(object); 1064 return (EIO); 1065 } 1066 vm_page_xunbusy(ma[0]); 1067 for (i = 1; i < initial_pagein; i++) 1068 vm_page_readahead_finish(ma[i]); 1069 } 1070 vm_page_lock(ma[0]); 1071 vm_page_hold(ma[0]); 1072 vm_page_activate(ma[0]); 1073 vm_page_unlock(ma[0]); 1074 VM_OBJECT_WUNLOCK(object); 1075 1076 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1077 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1078 1079 return (0); 1080 } 1081 1082 void 1083 exec_unmap_first_page(struct image_params *imgp) 1084 { 1085 vm_page_t m; 1086 1087 if (imgp->firstpage != NULL) { 1088 m = sf_buf_page(imgp->firstpage); 1089 sf_buf_free(imgp->firstpage); 1090 imgp->firstpage = NULL; 1091 vm_page_lock(m); 1092 vm_page_unhold(m); 1093 vm_page_unlock(m); 1094 } 1095 } 1096 1097 /* 1098 * Destroy old address space, and allocate a new stack. 1099 * The new stack is only sgrowsiz large because it is grown 1100 * automatically on a page fault. 1101 */ 1102 int 1103 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1104 { 1105 int error; 1106 struct proc *p = imgp->proc; 1107 struct vmspace *vmspace = p->p_vmspace; 1108 vm_object_t obj; 1109 struct rlimit rlim_stack; 1110 vm_offset_t sv_minuser, stack_addr; 1111 vm_map_t map; 1112 u_long ssiz; 1113 1114 imgp->vmspace_destroyed = 1; 1115 imgp->sysent = sv; 1116 1117 umtx_exec(p); 1118 itimers_exec(p); 1119 1120 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1121 1122 /* 1123 * Blow away entire process VM, if address space not shared, 1124 * otherwise, create a new VM space so that other threads are 1125 * not disrupted 1126 */ 1127 map = &vmspace->vm_map; 1128 if (map_at_zero) 1129 sv_minuser = sv->sv_minuser; 1130 else 1131 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1132 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1133 vm_map_max(map) == sv->sv_maxuser && 1134 cpu_exec_vmspace_reuse(p, map)) { 1135 shmexit(vmspace); 1136 pmap_remove_pages(vmspace_pmap(vmspace)); 1137 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1138 /* 1139 * An exec terminates mlockall(MCL_FUTURE), ASLR state 1140 * must be re-evaluated. 1141 */ 1142 vm_map_lock(map); 1143 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1144 MAP_ASLR_IGNSTART); 1145 vm_map_unlock(map); 1146 } else { 1147 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1148 if (error) 1149 return (error); 1150 vmspace = p->p_vmspace; 1151 map = &vmspace->vm_map; 1152 } 1153 map->flags |= imgp->map_flags; 1154 1155 /* Map a shared page */ 1156 obj = sv->sv_shared_page_obj; 1157 if (obj != NULL) { 1158 vm_object_reference(obj); 1159 error = vm_map_fixed(map, obj, 0, 1160 sv->sv_shared_page_base, sv->sv_shared_page_len, 1161 VM_PROT_READ | VM_PROT_EXECUTE, 1162 VM_PROT_READ | VM_PROT_EXECUTE, 1163 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1164 if (error != KERN_SUCCESS) { 1165 vm_object_deallocate(obj); 1166 return (vm_mmap_to_errno(error)); 1167 } 1168 } 1169 1170 /* Allocate a new stack */ 1171 if (imgp->stack_sz != 0) { 1172 ssiz = trunc_page(imgp->stack_sz); 1173 PROC_LOCK(p); 1174 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1175 PROC_UNLOCK(p); 1176 if (ssiz > rlim_stack.rlim_max) 1177 ssiz = rlim_stack.rlim_max; 1178 if (ssiz > rlim_stack.rlim_cur) { 1179 rlim_stack.rlim_cur = ssiz; 1180 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1181 } 1182 } else if (sv->sv_maxssiz != NULL) { 1183 ssiz = *sv->sv_maxssiz; 1184 } else { 1185 ssiz = maxssiz; 1186 } 1187 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1188 if (ssiz < imgp->eff_stack_sz) 1189 imgp->eff_stack_sz = ssiz; 1190 stack_addr = sv->sv_usrstack - ssiz; 1191 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1192 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1193 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1194 if (error != KERN_SUCCESS) 1195 return (vm_mmap_to_errno(error)); 1196 1197 /* 1198 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1199 * are still used to enforce the stack rlimit on the process stack. 1200 */ 1201 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1202 vmspace->vm_maxsaddr = (char *)stack_addr; 1203 1204 return (0); 1205 } 1206 1207 /* 1208 * Copy out argument and environment strings from the old process address 1209 * space into the temporary string buffer. 1210 */ 1211 int 1212 exec_copyin_args(struct image_args *args, char *fname, 1213 enum uio_seg segflg, char **argv, char **envv) 1214 { 1215 u_long argp, envp; 1216 int error; 1217 size_t length; 1218 1219 bzero(args, sizeof(*args)); 1220 if (argv == NULL) 1221 return (EFAULT); 1222 1223 /* 1224 * Allocate demand-paged memory for the file name, argument, and 1225 * environment strings. 1226 */ 1227 error = exec_alloc_args(args); 1228 if (error != 0) 1229 return (error); 1230 1231 /* 1232 * Copy the file name. 1233 */ 1234 if (fname != NULL) { 1235 args->fname = args->buf; 1236 error = (segflg == UIO_SYSSPACE) ? 1237 copystr(fname, args->fname, PATH_MAX, &length) : 1238 copyinstr(fname, args->fname, PATH_MAX, &length); 1239 if (error != 0) 1240 goto err_exit; 1241 } else 1242 length = 0; 1243 1244 args->begin_argv = args->buf + length; 1245 args->endp = args->begin_argv; 1246 args->stringspace = ARG_MAX; 1247 1248 /* 1249 * extract arguments first 1250 */ 1251 for (;;) { 1252 error = fueword(argv++, &argp); 1253 if (error == -1) { 1254 error = EFAULT; 1255 goto err_exit; 1256 } 1257 if (argp == 0) 1258 break; 1259 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1260 args->stringspace, &length); 1261 if (error != 0) { 1262 if (error == ENAMETOOLONG) 1263 error = E2BIG; 1264 goto err_exit; 1265 } 1266 args->stringspace -= length; 1267 args->endp += length; 1268 args->argc++; 1269 } 1270 1271 args->begin_envv = args->endp; 1272 1273 /* 1274 * extract environment strings 1275 */ 1276 if (envv) { 1277 for (;;) { 1278 error = fueword(envv++, &envp); 1279 if (error == -1) { 1280 error = EFAULT; 1281 goto err_exit; 1282 } 1283 if (envp == 0) 1284 break; 1285 error = copyinstr((void *)(uintptr_t)envp, 1286 args->endp, args->stringspace, &length); 1287 if (error != 0) { 1288 if (error == ENAMETOOLONG) 1289 error = E2BIG; 1290 goto err_exit; 1291 } 1292 args->stringspace -= length; 1293 args->endp += length; 1294 args->envc++; 1295 } 1296 } 1297 1298 return (0); 1299 1300 err_exit: 1301 exec_free_args(args); 1302 return (error); 1303 } 1304 1305 int 1306 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1307 const void *data, size_t datalen, const int *fds, size_t fdslen) 1308 { 1309 struct filedesc *ofdp; 1310 const char *p; 1311 int *kfds; 1312 int error; 1313 1314 memset(args, '\0', sizeof(*args)); 1315 ofdp = td->td_proc->p_fd; 1316 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1317 return (E2BIG); 1318 error = exec_alloc_args(args); 1319 if (error != 0) 1320 return (error); 1321 1322 args->begin_argv = args->buf; 1323 args->stringspace = ARG_MAX; 1324 1325 if (datalen > 0) { 1326 /* 1327 * Argument buffer has been provided. Copy it into the 1328 * kernel as a single string and add a terminating null 1329 * byte. 1330 */ 1331 error = copyin(data, args->begin_argv, datalen); 1332 if (error != 0) 1333 goto err_exit; 1334 args->begin_argv[datalen] = '\0'; 1335 args->endp = args->begin_argv + datalen + 1; 1336 args->stringspace -= datalen + 1; 1337 1338 /* 1339 * Traditional argument counting. Count the number of 1340 * null bytes. 1341 */ 1342 for (p = args->begin_argv; p < args->endp; ++p) 1343 if (*p == '\0') 1344 ++args->argc; 1345 } else { 1346 /* No argument buffer provided. */ 1347 args->endp = args->begin_argv; 1348 } 1349 /* There are no environment variables. */ 1350 args->begin_envv = args->endp; 1351 1352 /* Create new file descriptor table. */ 1353 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1354 error = copyin(fds, kfds, fdslen * sizeof(int)); 1355 if (error != 0) { 1356 free(kfds, M_TEMP); 1357 goto err_exit; 1358 } 1359 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1360 free(kfds, M_TEMP); 1361 if (error != 0) 1362 goto err_exit; 1363 1364 return (0); 1365 err_exit: 1366 exec_free_args(args); 1367 return (error); 1368 } 1369 1370 struct exec_args_kva { 1371 vm_offset_t addr; 1372 u_int gen; 1373 SLIST_ENTRY(exec_args_kva) next; 1374 }; 1375 1376 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1377 1378 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1379 static struct mtx exec_args_kva_mtx; 1380 static u_int exec_args_gen; 1381 1382 static void 1383 exec_prealloc_args_kva(void *arg __unused) 1384 { 1385 struct exec_args_kva *argkva; 1386 u_int i; 1387 1388 SLIST_INIT(&exec_args_kva_freelist); 1389 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1390 for (i = 0; i < exec_map_entries; i++) { 1391 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1392 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1393 argkva->gen = exec_args_gen; 1394 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1395 } 1396 } 1397 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1398 1399 static vm_offset_t 1400 exec_alloc_args_kva(void **cookie) 1401 { 1402 struct exec_args_kva *argkva; 1403 1404 argkva = (void *)atomic_readandclear_ptr( 1405 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1406 if (argkva == NULL) { 1407 mtx_lock(&exec_args_kva_mtx); 1408 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1409 (void)mtx_sleep(&exec_args_kva_freelist, 1410 &exec_args_kva_mtx, 0, "execkva", 0); 1411 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1412 mtx_unlock(&exec_args_kva_mtx); 1413 } 1414 *(struct exec_args_kva **)cookie = argkva; 1415 return (argkva->addr); 1416 } 1417 1418 static void 1419 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1420 { 1421 vm_offset_t base; 1422 1423 base = argkva->addr; 1424 if (argkva->gen != gen) { 1425 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1426 MADV_FREE); 1427 argkva->gen = gen; 1428 } 1429 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1430 (uintptr_t)NULL, (uintptr_t)argkva)) { 1431 mtx_lock(&exec_args_kva_mtx); 1432 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1433 wakeup_one(&exec_args_kva_freelist); 1434 mtx_unlock(&exec_args_kva_mtx); 1435 } 1436 } 1437 1438 static void 1439 exec_free_args_kva(void *cookie) 1440 { 1441 1442 exec_release_args_kva(cookie, exec_args_gen); 1443 } 1444 1445 static void 1446 exec_args_kva_lowmem(void *arg __unused) 1447 { 1448 SLIST_HEAD(, exec_args_kva) head; 1449 struct exec_args_kva *argkva; 1450 u_int gen; 1451 int i; 1452 1453 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1454 1455 /* 1456 * Force an madvise of each KVA range. Any currently allocated ranges 1457 * will have MADV_FREE applied once they are freed. 1458 */ 1459 SLIST_INIT(&head); 1460 mtx_lock(&exec_args_kva_mtx); 1461 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1462 mtx_unlock(&exec_args_kva_mtx); 1463 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1464 SLIST_REMOVE_HEAD(&head, next); 1465 exec_release_args_kva(argkva, gen); 1466 } 1467 1468 CPU_FOREACH(i) { 1469 argkva = (void *)atomic_readandclear_ptr( 1470 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1471 if (argkva != NULL) 1472 exec_release_args_kva(argkva, gen); 1473 } 1474 } 1475 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1476 EVENTHANDLER_PRI_ANY); 1477 1478 /* 1479 * Allocate temporary demand-paged, zero-filled memory for the file name, 1480 * argument, and environment strings. 1481 */ 1482 int 1483 exec_alloc_args(struct image_args *args) 1484 { 1485 1486 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1487 return (0); 1488 } 1489 1490 void 1491 exec_free_args(struct image_args *args) 1492 { 1493 1494 if (args->buf != NULL) { 1495 exec_free_args_kva(args->bufkva); 1496 args->buf = NULL; 1497 } 1498 if (args->fname_buf != NULL) { 1499 free(args->fname_buf, M_TEMP); 1500 args->fname_buf = NULL; 1501 } 1502 if (args->fdp != NULL) 1503 fdescfree_remapped(args->fdp); 1504 } 1505 1506 void 1507 exec_stackgap(struct image_params *imgp, uintptr_t *dp) 1508 { 1509 if (imgp->sysent->sv_stackgap == NULL || 1510 (imgp->proc->p_fctl0 & (NT_FREEBSD_FCTL_ASLR_DISABLE | 1511 NT_FREEBSD_FCTL_ASG_DISABLE)) != 0 || 1512 (imgp->map_flags & MAP_ASLR) == 0) 1513 return; 1514 imgp->sysent->sv_stackgap(imgp, (u_long *)dp); 1515 } 1516 1517 /* 1518 * Copy strings out to the new process address space, constructing new arg 1519 * and env vector tables. Return a pointer to the base so that it can be used 1520 * as the initial stack pointer. 1521 */ 1522 register_t * 1523 exec_copyout_strings(struct image_params *imgp) 1524 { 1525 int argc, envc; 1526 char **vectp; 1527 char *stringp; 1528 uintptr_t destp; 1529 register_t *stack_base; 1530 struct ps_strings *arginfo; 1531 struct proc *p; 1532 size_t execpath_len; 1533 int szsigcode, szps; 1534 char canary[sizeof(long) * 8]; 1535 1536 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1537 /* 1538 * Calculate string base and vector table pointers. 1539 * Also deal with signal trampoline code for this exec type. 1540 */ 1541 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1542 execpath_len = strlen(imgp->execpath) + 1; 1543 else 1544 execpath_len = 0; 1545 p = imgp->proc; 1546 szsigcode = 0; 1547 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1548 if (p->p_sysent->sv_sigcode_base == 0) { 1549 if (p->p_sysent->sv_szsigcode != NULL) 1550 szsigcode = *(p->p_sysent->sv_szsigcode); 1551 } 1552 destp = (uintptr_t)arginfo; 1553 1554 /* 1555 * install sigcode 1556 */ 1557 if (szsigcode != 0) { 1558 destp -= szsigcode; 1559 destp = rounddown2(destp, sizeof(void *)); 1560 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1561 } 1562 1563 /* 1564 * Copy the image path for the rtld. 1565 */ 1566 if (execpath_len != 0) { 1567 destp -= execpath_len; 1568 destp = rounddown2(destp, sizeof(void *)); 1569 imgp->execpathp = destp; 1570 copyout(imgp->execpath, (void *)destp, execpath_len); 1571 } 1572 1573 /* 1574 * Prepare the canary for SSP. 1575 */ 1576 arc4rand(canary, sizeof(canary), 0); 1577 destp -= sizeof(canary); 1578 imgp->canary = destp; 1579 copyout(canary, (void *)destp, sizeof(canary)); 1580 imgp->canarylen = sizeof(canary); 1581 1582 /* 1583 * Prepare the pagesizes array. 1584 */ 1585 destp -= szps; 1586 destp = rounddown2(destp, sizeof(void *)); 1587 imgp->pagesizes = destp; 1588 copyout(pagesizes, (void *)destp, szps); 1589 imgp->pagesizeslen = szps; 1590 1591 destp -= ARG_MAX - imgp->args->stringspace; 1592 destp = rounddown2(destp, sizeof(void *)); 1593 1594 exec_stackgap(imgp, &destp); 1595 vectp = (char **)destp; 1596 1597 if (imgp->auxargs) { 1598 /* 1599 * Allocate room on the stack for the ELF auxargs 1600 * array. It has up to AT_COUNT entries. 1601 */ 1602 vectp -= howmany(AT_COUNT * sizeof(Elf_Auxinfo), 1603 sizeof(*vectp)); 1604 } 1605 1606 /* 1607 * Allocate room for the argv[] and env vectors including the 1608 * terminating NULL pointers. 1609 */ 1610 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1611 1612 /* 1613 * vectp also becomes our initial stack base 1614 */ 1615 stack_base = (register_t *)vectp; 1616 1617 stringp = imgp->args->begin_argv; 1618 argc = imgp->args->argc; 1619 envc = imgp->args->envc; 1620 1621 /* 1622 * Copy out strings - arguments and environment. 1623 */ 1624 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1625 1626 /* 1627 * Fill in "ps_strings" struct for ps, w, etc. 1628 */ 1629 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1630 suword32(&arginfo->ps_nargvstr, argc); 1631 1632 /* 1633 * Fill in argument portion of vector table. 1634 */ 1635 for (; argc > 0; --argc) { 1636 suword(vectp++, (long)(intptr_t)destp); 1637 while (*stringp++ != 0) 1638 destp++; 1639 destp++; 1640 } 1641 1642 /* a null vector table pointer separates the argp's from the envp's */ 1643 suword(vectp++, 0); 1644 1645 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1646 suword32(&arginfo->ps_nenvstr, envc); 1647 1648 /* 1649 * Fill in environment portion of vector table. 1650 */ 1651 for (; envc > 0; --envc) { 1652 suword(vectp++, (long)(intptr_t)destp); 1653 while (*stringp++ != 0) 1654 destp++; 1655 destp++; 1656 } 1657 1658 /* end of vector table is a null pointer */ 1659 suword(vectp, 0); 1660 1661 return (stack_base); 1662 } 1663 1664 /* 1665 * Check permissions of file to execute. 1666 * Called with imgp->vp locked. 1667 * Return 0 for success or error code on failure. 1668 */ 1669 int 1670 exec_check_permissions(struct image_params *imgp) 1671 { 1672 struct vnode *vp = imgp->vp; 1673 struct vattr *attr = imgp->attr; 1674 struct thread *td; 1675 int error; 1676 1677 td = curthread; 1678 1679 /* Get file attributes */ 1680 error = VOP_GETATTR(vp, attr, td->td_ucred); 1681 if (error) 1682 return (error); 1683 1684 #ifdef MAC 1685 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1686 if (error) 1687 return (error); 1688 #endif 1689 1690 /* 1691 * 1) Check if file execution is disabled for the filesystem that 1692 * this file resides on. 1693 * 2) Ensure that at least one execute bit is on. Otherwise, a 1694 * privileged user will always succeed, and we don't want this 1695 * to happen unless the file really is executable. 1696 * 3) Ensure that the file is a regular file. 1697 */ 1698 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1699 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1700 (attr->va_type != VREG)) 1701 return (EACCES); 1702 1703 /* 1704 * Zero length files can't be exec'd 1705 */ 1706 if (attr->va_size == 0) 1707 return (ENOEXEC); 1708 1709 /* 1710 * Check for execute permission to file based on current credentials. 1711 */ 1712 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1713 if (error) 1714 return (error); 1715 1716 /* 1717 * Check number of open-for-writes on the file and deny execution 1718 * if there are any. 1719 * 1720 * Add a text reference now so no one can write to the 1721 * executable while we're activating it. 1722 * 1723 * Remember if this was set before and unset it in case this is not 1724 * actually an executable image. 1725 */ 1726 error = VOP_SET_TEXT(vp); 1727 if (error != 0) 1728 return (error); 1729 imgp->textset = true; 1730 1731 /* 1732 * Call filesystem specific open routine (which does nothing in the 1733 * general case). 1734 */ 1735 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1736 if (error == 0) 1737 imgp->opened = 1; 1738 return (error); 1739 } 1740 1741 /* 1742 * Exec handler registration 1743 */ 1744 int 1745 exec_register(const struct execsw *execsw_arg) 1746 { 1747 const struct execsw **es, **xs, **newexecsw; 1748 u_int count = 2; /* New slot and trailing NULL */ 1749 1750 if (execsw) 1751 for (es = execsw; *es; es++) 1752 count++; 1753 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1754 xs = newexecsw; 1755 if (execsw) 1756 for (es = execsw; *es; es++) 1757 *xs++ = *es; 1758 *xs++ = execsw_arg; 1759 *xs = NULL; 1760 if (execsw) 1761 free(execsw, M_TEMP); 1762 execsw = newexecsw; 1763 return (0); 1764 } 1765 1766 int 1767 exec_unregister(const struct execsw *execsw_arg) 1768 { 1769 const struct execsw **es, **xs, **newexecsw; 1770 int count = 1; 1771 1772 if (execsw == NULL) 1773 panic("unregister with no handlers left?\n"); 1774 1775 for (es = execsw; *es; es++) { 1776 if (*es == execsw_arg) 1777 break; 1778 } 1779 if (*es == NULL) 1780 return (ENOENT); 1781 for (es = execsw; *es; es++) 1782 if (*es != execsw_arg) 1783 count++; 1784 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1785 xs = newexecsw; 1786 for (es = execsw; *es; es++) 1787 if (*es != execsw_arg) 1788 *xs++ = *es; 1789 *xs = NULL; 1790 if (execsw) 1791 free(execsw, M_TEMP); 1792 execsw = newexecsw; 1793 return (0); 1794 }
Cache object: 28dfea99f7d4e3a85a743ca33e181bab
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