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/vnode.h> 72 #include <sys/wait.h> 73 #ifdef KTRACE 74 #include <sys/ktrace.h> 75 #endif 76 77 #include <vm/vm.h> 78 #include <vm/vm_param.h> 79 #include <vm/pmap.h> 80 #include <vm/vm_page.h> 81 #include <vm/vm_map.h> 82 #include <vm/vm_kern.h> 83 #include <vm/vm_extern.h> 84 #include <vm/vm_object.h> 85 #include <vm/vm_pager.h> 86 87 #ifdef HWPMC_HOOKS 88 #include <sys/pmckern.h> 89 #endif 90 91 #include <machine/reg.h> 92 93 #include <security/audit/audit.h> 94 #include <security/mac/mac_framework.h> 95 96 #ifdef KDTRACE_HOOKS 97 #include <sys/dtrace_bsd.h> 98 dtrace_execexit_func_t dtrace_fasttrap_exec; 99 #endif 100 101 SDT_PROVIDER_DECLARE(proc); 102 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 103 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 104 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 105 106 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 107 108 int coredump_pack_fileinfo = 1; 109 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 110 &coredump_pack_fileinfo, 0, 111 "Enable file path packing in 'procstat -f' coredump notes"); 112 113 int coredump_pack_vmmapinfo = 1; 114 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 115 &coredump_pack_vmmapinfo, 0, 116 "Enable file path packing in 'procstat -v' coredump notes"); 117 118 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 119 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 120 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 121 static int do_execve(struct thread *td, struct image_args *args, 122 struct mac *mac_p); 123 124 /* XXX This should be vm_size_t. */ 125 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 126 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", ""); 127 128 /* XXX This should be vm_size_t. */ 129 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 130 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", ""); 131 132 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 133 NULL, 0, sysctl_kern_stackprot, "I", ""); 134 135 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 136 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 137 &ps_arg_cache_limit, 0, ""); 138 139 static int disallow_high_osrel; 140 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 141 &disallow_high_osrel, 0, 142 "Disallow execution of binaries built for higher version of the world"); 143 144 static int map_at_zero = 0; 145 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 146 "Permit processes to map an object at virtual address 0."); 147 148 static int 149 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 150 { 151 struct proc *p; 152 int error; 153 154 p = curproc; 155 #ifdef SCTL_MASK32 156 if (req->flags & SCTL_MASK32) { 157 unsigned int val; 158 val = (unsigned int)p->p_sysent->sv_psstrings; 159 error = SYSCTL_OUT(req, &val, sizeof(val)); 160 } else 161 #endif 162 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 163 sizeof(p->p_sysent->sv_psstrings)); 164 return error; 165 } 166 167 static int 168 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 169 { 170 struct proc *p; 171 int error; 172 173 p = curproc; 174 #ifdef SCTL_MASK32 175 if (req->flags & SCTL_MASK32) { 176 unsigned int val; 177 val = (unsigned int)p->p_sysent->sv_usrstack; 178 error = SYSCTL_OUT(req, &val, sizeof(val)); 179 } else 180 #endif 181 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 182 sizeof(p->p_sysent->sv_usrstack)); 183 return error; 184 } 185 186 static int 187 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 188 { 189 struct proc *p; 190 191 p = curproc; 192 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 193 sizeof(p->p_sysent->sv_stackprot))); 194 } 195 196 /* 197 * Each of the items is a pointer to a `const struct execsw', hence the 198 * double pointer here. 199 */ 200 static const struct execsw **execsw; 201 202 #ifndef _SYS_SYSPROTO_H_ 203 struct execve_args { 204 char *fname; 205 char **argv; 206 char **envv; 207 }; 208 #endif 209 210 int 211 sys_execve(struct thread *td, struct execve_args *uap) 212 { 213 struct image_args args; 214 struct vmspace *oldvmspace; 215 int error; 216 217 error = pre_execve(td, &oldvmspace); 218 if (error != 0) 219 return (error); 220 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 221 uap->argv, uap->envv); 222 if (error == 0) 223 error = kern_execve(td, &args, NULL); 224 post_execve(td, error, oldvmspace); 225 return (error); 226 } 227 228 #ifndef _SYS_SYSPROTO_H_ 229 struct fexecve_args { 230 int fd; 231 char **argv; 232 char **envv; 233 } 234 #endif 235 int 236 sys_fexecve(struct thread *td, struct fexecve_args *uap) 237 { 238 struct image_args args; 239 struct vmspace *oldvmspace; 240 int error; 241 242 error = pre_execve(td, &oldvmspace); 243 if (error != 0) 244 return (error); 245 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 246 uap->argv, uap->envv); 247 if (error == 0) { 248 args.fd = uap->fd; 249 error = kern_execve(td, &args, NULL); 250 } 251 post_execve(td, error, oldvmspace); 252 return (error); 253 } 254 255 #ifndef _SYS_SYSPROTO_H_ 256 struct __mac_execve_args { 257 char *fname; 258 char **argv; 259 char **envv; 260 struct mac *mac_p; 261 }; 262 #endif 263 264 int 265 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 266 { 267 #ifdef MAC 268 struct image_args args; 269 struct vmspace *oldvmspace; 270 int error; 271 272 error = pre_execve(td, &oldvmspace); 273 if (error != 0) 274 return (error); 275 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 276 uap->argv, uap->envv); 277 if (error == 0) 278 error = kern_execve(td, &args, uap->mac_p); 279 post_execve(td, error, oldvmspace); 280 return (error); 281 #else 282 return (ENOSYS); 283 #endif 284 } 285 286 int 287 pre_execve(struct thread *td, struct vmspace **oldvmspace) 288 { 289 struct proc *p; 290 int error; 291 292 KASSERT(td == curthread, ("non-current thread %p", td)); 293 error = 0; 294 p = td->td_proc; 295 if ((p->p_flag & P_HADTHREADS) != 0) { 296 PROC_LOCK(p); 297 if (thread_single(p, SINGLE_BOUNDARY) != 0) 298 error = ERESTART; 299 PROC_UNLOCK(p); 300 } 301 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 302 ("nested execve")); 303 *oldvmspace = p->p_vmspace; 304 return (error); 305 } 306 307 void 308 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 309 { 310 struct proc *p; 311 312 KASSERT(td == curthread, ("non-current thread %p", td)); 313 p = td->td_proc; 314 if ((p->p_flag & P_HADTHREADS) != 0) { 315 PROC_LOCK(p); 316 /* 317 * If success, we upgrade to SINGLE_EXIT state to 318 * force other threads to suicide. 319 */ 320 if (error == EJUSTRETURN) 321 thread_single(p, SINGLE_EXIT); 322 else 323 thread_single_end(p, SINGLE_BOUNDARY); 324 PROC_UNLOCK(p); 325 } 326 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 327 KASSERT(p->p_vmspace != oldvmspace, 328 ("oldvmspace still used")); 329 vmspace_free(oldvmspace); 330 td->td_pflags &= ~TDP_EXECVMSPC; 331 } 332 } 333 334 /* 335 * XXX: kern_execve has the astonishing property of not always returning to 336 * the caller. If sufficiently bad things happen during the call to 337 * do_execve(), it can end up calling exit1(); as a result, callers must 338 * avoid doing anything which they might need to undo (e.g., allocating 339 * memory). 340 */ 341 int 342 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 343 { 344 345 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 346 exec_args_get_begin_envv(args) - args->begin_argv); 347 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc, 348 args->endp - exec_args_get_begin_envv(args)); 349 return (do_execve(td, args, mac_p)); 350 } 351 352 /* 353 * In-kernel implementation of execve(). All arguments are assumed to be 354 * userspace pointers from the passed thread. 355 */ 356 static int 357 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 358 { 359 struct proc *p = td->td_proc; 360 struct nameidata nd; 361 struct ucred *oldcred; 362 struct uidinfo *euip = NULL; 363 register_t *stack_base; 364 int error, i; 365 struct image_params image_params, *imgp; 366 struct vattr attr; 367 int (*img_first)(struct image_params *); 368 struct pargs *oldargs = NULL, *newargs = NULL; 369 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 370 #ifdef KTRACE 371 struct vnode *tracevp = NULL; 372 struct ucred *tracecred = NULL; 373 #endif 374 struct vnode *oldtextvp = NULL, *newtextvp; 375 int credential_changing; 376 #ifdef MAC 377 struct label *interpvplabel = NULL; 378 int will_transition; 379 #endif 380 #ifdef HWPMC_HOOKS 381 struct pmckern_procexec pe; 382 #endif 383 static const char fexecv_proc_title[] = "(fexecv)"; 384 385 imgp = &image_params; 386 387 /* 388 * Lock the process and set the P_INEXEC flag to indicate that 389 * it should be left alone until we're done here. This is 390 * necessary to avoid race conditions - e.g. in ptrace() - 391 * that might allow a local user to illicitly obtain elevated 392 * privileges. 393 */ 394 PROC_LOCK(p); 395 KASSERT((p->p_flag & P_INEXEC) == 0, 396 ("%s(): process already has P_INEXEC flag", __func__)); 397 p->p_flag |= P_INEXEC; 398 PROC_UNLOCK(p); 399 400 /* 401 * Initialize part of the common data 402 */ 403 bzero(imgp, sizeof(*imgp)); 404 imgp->proc = p; 405 imgp->attr = &attr; 406 imgp->args = args; 407 oldcred = p->p_ucred; 408 409 #ifdef MAC 410 error = mac_execve_enter(imgp, mac_p); 411 if (error) 412 goto exec_fail; 413 #endif 414 415 /* 416 * Translate the file name. namei() returns a vnode pointer 417 * in ni_vp among other things. 418 * 419 * XXXAUDIT: It would be desirable to also audit the name of the 420 * interpreter if this is an interpreted binary. 421 */ 422 if (args->fname != NULL) { 423 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 424 SAVENAME | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 425 } 426 427 SDT_PROBE1(proc, , , exec, args->fname); 428 429 interpret: 430 if (args->fname != NULL) { 431 #ifdef CAPABILITY_MODE 432 /* 433 * While capability mode can't reach this point via direct 434 * path arguments to execve(), we also don't allow 435 * interpreters to be used in capability mode (for now). 436 * Catch indirect lookups and return a permissions error. 437 */ 438 if (IN_CAPABILITY_MODE(td)) { 439 error = ECAPMODE; 440 goto exec_fail; 441 } 442 #endif 443 error = namei(&nd); 444 if (error) 445 goto exec_fail; 446 447 newtextvp = nd.ni_vp; 448 imgp->vp = newtextvp; 449 } else { 450 AUDIT_ARG_FD(args->fd); 451 /* 452 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 453 */ 454 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp); 455 if (error) 456 goto exec_fail; 457 vn_lock(newtextvp, LK_SHARED | LK_RETRY); 458 AUDIT_ARG_VNODE1(newtextvp); 459 imgp->vp = newtextvp; 460 } 461 462 /* 463 * Check file permissions. Also 'opens' file and sets its vnode to 464 * text mode. 465 */ 466 error = exec_check_permissions(imgp); 467 if (error) 468 goto exec_fail_dealloc; 469 470 imgp->object = imgp->vp->v_object; 471 if (imgp->object != NULL) 472 vm_object_reference(imgp->object); 473 474 error = exec_map_first_page(imgp); 475 if (error) 476 goto exec_fail_dealloc; 477 478 imgp->proc->p_osrel = 0; 479 imgp->proc->p_fctl0 = 0; 480 481 /* 482 * Implement image setuid/setgid. 483 * 484 * Determine new credentials before attempting image activators 485 * so that it can be used by process_exec handlers to determine 486 * credential/setid changes. 487 * 488 * Don't honor setuid/setgid if the filesystem prohibits it or if 489 * the process is being traced. 490 * 491 * We disable setuid/setgid/etc in capability mode on the basis 492 * that most setugid applications are not written with that 493 * environment in mind, and will therefore almost certainly operate 494 * incorrectly. In principle there's no reason that setugid 495 * applications might not be useful in capability mode, so we may want 496 * to reconsider this conservative design choice in the future. 497 * 498 * XXXMAC: For the time being, use NOSUID to also prohibit 499 * transitions on the file system. 500 */ 501 credential_changing = 0; 502 credential_changing |= (attr.va_mode & S_ISUID) && 503 oldcred->cr_uid != attr.va_uid; 504 credential_changing |= (attr.va_mode & S_ISGID) && 505 oldcred->cr_gid != attr.va_gid; 506 #ifdef MAC 507 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 508 interpvplabel, imgp); 509 credential_changing |= will_transition; 510 #endif 511 512 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 513 if (credential_changing) 514 imgp->proc->p_pdeathsig = 0; 515 516 if (credential_changing && 517 #ifdef CAPABILITY_MODE 518 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 519 #endif 520 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 521 (p->p_flag & P_TRACED) == 0) { 522 imgp->credential_setid = true; 523 VOP_UNLOCK(imgp->vp, 0); 524 imgp->newcred = crdup(oldcred); 525 if (attr.va_mode & S_ISUID) { 526 euip = uifind(attr.va_uid); 527 change_euid(imgp->newcred, euip); 528 } 529 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 530 if (attr.va_mode & S_ISGID) 531 change_egid(imgp->newcred, attr.va_gid); 532 /* 533 * Implement correct POSIX saved-id behavior. 534 * 535 * XXXMAC: Note that the current logic will save the 536 * uid and gid if a MAC domain transition occurs, even 537 * though maybe it shouldn't. 538 */ 539 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 540 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 541 } else { 542 /* 543 * Implement correct POSIX saved-id behavior. 544 * 545 * XXX: It's not clear that the existing behavior is 546 * POSIX-compliant. A number of sources indicate that the 547 * saved uid/gid should only be updated if the new ruid is 548 * not equal to the old ruid, or the new euid is not equal 549 * to the old euid and the new euid is not equal to the old 550 * ruid. The FreeBSD code always updates the saved uid/gid. 551 * Also, this code uses the new (replaced) euid and egid as 552 * the source, which may or may not be the right ones to use. 553 */ 554 if (oldcred->cr_svuid != oldcred->cr_uid || 555 oldcred->cr_svgid != oldcred->cr_gid) { 556 VOP_UNLOCK(imgp->vp, 0); 557 imgp->newcred = crdup(oldcred); 558 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 559 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 560 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 561 } 562 } 563 /* The new credentials are installed into the process later. */ 564 565 /* 566 * Do the best to calculate the full path to the image file. 567 */ 568 if (args->fname != NULL && args->fname[0] == '/') 569 imgp->execpath = args->fname; 570 else { 571 VOP_UNLOCK(imgp->vp, 0); 572 if (vn_fullpath(td, imgp->vp, &imgp->execpath, 573 &imgp->freepath) != 0) 574 imgp->execpath = args->fname; 575 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 576 } 577 578 /* 579 * If the current process has a special image activator it 580 * wants to try first, call it. For example, emulating shell 581 * scripts differently. 582 */ 583 error = -1; 584 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 585 error = img_first(imgp); 586 587 /* 588 * Loop through the list of image activators, calling each one. 589 * An activator returns -1 if there is no match, 0 on success, 590 * and an error otherwise. 591 */ 592 for (i = 0; error == -1 && execsw[i]; ++i) { 593 if (execsw[i]->ex_imgact == NULL || 594 execsw[i]->ex_imgact == img_first) { 595 continue; 596 } 597 error = (*execsw[i]->ex_imgact)(imgp); 598 } 599 600 if (error) { 601 if (error == -1) 602 error = ENOEXEC; 603 goto exec_fail_dealloc; 604 } 605 606 /* 607 * Special interpreter operation, cleanup and loop up to try to 608 * activate the interpreter. 609 */ 610 if (imgp->interpreted) { 611 exec_unmap_first_page(imgp); 612 /* 613 * The text reference needs to be removed for scripts. 614 * There is a short period before we determine that 615 * something is a script where text reference is active. 616 * The vnode lock is held over this entire period 617 * so nothing should illegitimately be blocked. 618 */ 619 VOP_UNSET_TEXT_CHECKED(imgp->vp); 620 /* free name buffer and old vnode */ 621 if (args->fname != NULL) 622 NDFREE(&nd, NDF_ONLY_PNBUF); 623 #ifdef MAC 624 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 625 #endif 626 if (imgp->opened) { 627 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 628 imgp->opened = 0; 629 } 630 vput(newtextvp); 631 vm_object_deallocate(imgp->object); 632 imgp->object = NULL; 633 imgp->credential_setid = false; 634 if (imgp->newcred != NULL) { 635 crfree(imgp->newcred); 636 imgp->newcred = NULL; 637 } 638 imgp->execpath = NULL; 639 free(imgp->freepath, M_TEMP); 640 imgp->freepath = NULL; 641 /* set new name to that of the interpreter */ 642 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME, 643 UIO_SYSSPACE, imgp->interpreter_name, td); 644 args->fname = imgp->interpreter_name; 645 goto interpret; 646 } 647 648 /* 649 * NB: We unlock the vnode here because it is believed that none 650 * of the sv_copyout_strings/sv_fixup operations require the vnode. 651 */ 652 VOP_UNLOCK(imgp->vp, 0); 653 654 if (disallow_high_osrel && 655 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 656 error = ENOEXEC; 657 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 658 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 659 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 660 goto exec_fail_dealloc; 661 } 662 663 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 664 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 665 sys_cap_enter(td, NULL); 666 667 /* 668 * Copy out strings (args and env) and initialize stack base. 669 */ 670 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 671 672 /* 673 * Stack setup. 674 */ 675 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 676 if (error != 0) { 677 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 678 goto exec_fail_dealloc; 679 } 680 681 if (args->fdp != NULL) { 682 /* Install a brand new file descriptor table. */ 683 fdinstall_remapped(td, args->fdp); 684 args->fdp = NULL; 685 } else { 686 /* 687 * Keep on using the existing file descriptor table. For 688 * security and other reasons, the file descriptor table 689 * cannot be shared after an exec. 690 */ 691 fdunshare(td); 692 /* close files on exec */ 693 fdcloseexec(td); 694 } 695 696 /* 697 * Malloc things before we need locks. 698 */ 699 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 700 /* Cache arguments if they fit inside our allowance */ 701 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 702 newargs = pargs_alloc(i); 703 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 704 } 705 706 /* 707 * For security and other reasons, signal handlers cannot 708 * be shared after an exec. The new process gets a copy of the old 709 * handlers. In execsigs(), the new process will have its signals 710 * reset. 711 */ 712 if (sigacts_shared(p->p_sigacts)) { 713 oldsigacts = p->p_sigacts; 714 newsigacts = sigacts_alloc(); 715 sigacts_copy(newsigacts, oldsigacts); 716 } 717 718 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 719 720 PROC_LOCK(p); 721 if (oldsigacts) 722 p->p_sigacts = newsigacts; 723 /* Stop profiling */ 724 stopprofclock(p); 725 726 /* reset caught signals */ 727 execsigs(p); 728 729 /* name this process - nameiexec(p, ndp) */ 730 bzero(p->p_comm, sizeof(p->p_comm)); 731 if (args->fname) 732 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 733 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 734 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 735 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 736 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 737 #ifdef KTR 738 sched_clear_tdname(td); 739 #endif 740 741 /* 742 * mark as execed, wakeup the process that vforked (if any) and tell 743 * it that it now has its own resources back 744 */ 745 p->p_flag |= P_EXEC; 746 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 747 p->p_flag2 &= ~P2_NOTRACE; 748 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 749 p->p_flag2 &= ~P2_STKGAP_DISABLE; 750 if (p->p_flag & P_PPWAIT) { 751 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 752 cv_broadcast(&p->p_pwait); 753 /* STOPs are no longer ignored, arrange for AST */ 754 signotify(td); 755 } 756 757 /* 758 * Implement image setuid/setgid installation. 759 */ 760 if (imgp->credential_setid) { 761 /* 762 * Turn off syscall tracing for set-id programs, except for 763 * root. Record any set-id flags first to make sure that 764 * we do not regain any tracing during a possible block. 765 */ 766 setsugid(p); 767 768 #ifdef KTRACE 769 if (p->p_tracecred != NULL && 770 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED)) 771 ktrprocexec(p, &tracecred, &tracevp); 772 #endif 773 /* 774 * Close any file descriptors 0..2 that reference procfs, 775 * then make sure file descriptors 0..2 are in use. 776 * 777 * Both fdsetugidsafety() and fdcheckstd() may call functions 778 * taking sleepable locks, so temporarily drop our locks. 779 */ 780 PROC_UNLOCK(p); 781 VOP_UNLOCK(imgp->vp, 0); 782 fdsetugidsafety(td); 783 error = fdcheckstd(td); 784 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 785 if (error != 0) 786 goto exec_fail_dealloc; 787 PROC_LOCK(p); 788 #ifdef MAC 789 if (will_transition) { 790 mac_vnode_execve_transition(oldcred, imgp->newcred, 791 imgp->vp, interpvplabel, imgp); 792 } 793 #endif 794 } else { 795 if (oldcred->cr_uid == oldcred->cr_ruid && 796 oldcred->cr_gid == oldcred->cr_rgid) 797 p->p_flag &= ~P_SUGID; 798 } 799 /* 800 * Set the new credentials. 801 */ 802 if (imgp->newcred != NULL) { 803 proc_set_cred(p, imgp->newcred); 804 crfree(oldcred); 805 oldcred = NULL; 806 } 807 808 /* 809 * Store the vp for use in procfs. This vnode was referenced by namei 810 * or fgetvp_exec. 811 */ 812 oldtextvp = p->p_textvp; 813 p->p_textvp = newtextvp; 814 815 #ifdef KDTRACE_HOOKS 816 /* 817 * Tell the DTrace fasttrap provider about the exec if it 818 * has declared an interest. 819 */ 820 if (dtrace_fasttrap_exec) 821 dtrace_fasttrap_exec(p); 822 #endif 823 824 /* 825 * Notify others that we exec'd, and clear the P_INEXEC flag 826 * as we're now a bona fide freshly-execed process. 827 */ 828 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 829 p->p_flag &= ~P_INEXEC; 830 831 /* clear "fork but no exec" flag, as we _are_ execing */ 832 p->p_acflag &= ~AFORK; 833 834 /* 835 * Free any previous argument cache and replace it with 836 * the new argument cache, if any. 837 */ 838 oldargs = p->p_args; 839 p->p_args = newargs; 840 newargs = NULL; 841 842 PROC_UNLOCK(p); 843 844 #ifdef HWPMC_HOOKS 845 /* 846 * Check if system-wide sampling is in effect or if the 847 * current process is using PMCs. If so, do exec() time 848 * processing. This processing needs to happen AFTER the 849 * P_INEXEC flag is cleared. 850 */ 851 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 852 VOP_UNLOCK(imgp->vp, 0); 853 pe.pm_credentialschanged = credential_changing; 854 pe.pm_entryaddr = imgp->entry_addr; 855 856 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 857 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 858 } 859 #endif 860 861 /* Set values passed into the program in registers. */ 862 (*p->p_sysent->sv_setregs)(td, imgp, (u_long)(uintptr_t)stack_base); 863 864 vfs_mark_atime(imgp->vp, td->td_ucred); 865 866 SDT_PROBE1(proc, , , exec__success, args->fname); 867 868 exec_fail_dealloc: 869 if (imgp->firstpage != NULL) 870 exec_unmap_first_page(imgp); 871 872 if (imgp->vp != NULL) { 873 if (args->fname) 874 NDFREE(&nd, NDF_ONLY_PNBUF); 875 if (imgp->opened) 876 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 877 if (imgp->textset) 878 VOP_UNSET_TEXT_CHECKED(imgp->vp); 879 if (error != 0) 880 vput(imgp->vp); 881 else 882 VOP_UNLOCK(imgp->vp, 0); 883 } 884 885 if (imgp->object != NULL) 886 vm_object_deallocate(imgp->object); 887 888 free(imgp->freepath, M_TEMP); 889 890 if (error == 0) { 891 if (p->p_ptevents & PTRACE_EXEC) { 892 PROC_LOCK(p); 893 if (p->p_ptevents & PTRACE_EXEC) 894 td->td_dbgflags |= TDB_EXEC; 895 PROC_UNLOCK(p); 896 } 897 898 /* 899 * Stop the process here if its stop event mask has 900 * the S_EXEC bit set. 901 */ 902 STOPEVENT(p, S_EXEC, 0); 903 } else { 904 exec_fail: 905 /* we're done here, clear P_INEXEC */ 906 PROC_LOCK(p); 907 p->p_flag &= ~P_INEXEC; 908 PROC_UNLOCK(p); 909 910 SDT_PROBE1(proc, , , exec__failure, error); 911 } 912 913 if (imgp->newcred != NULL && oldcred != NULL) 914 crfree(imgp->newcred); 915 916 #ifdef MAC 917 mac_execve_exit(imgp); 918 mac_execve_interpreter_exit(interpvplabel); 919 #endif 920 exec_free_args(args); 921 922 /* 923 * Handle deferred decrement of ref counts. 924 */ 925 if (oldtextvp != NULL) 926 vrele(oldtextvp); 927 #ifdef KTRACE 928 if (tracevp != NULL) 929 vrele(tracevp); 930 if (tracecred != NULL) 931 crfree(tracecred); 932 #endif 933 pargs_drop(oldargs); 934 pargs_drop(newargs); 935 if (oldsigacts != NULL) 936 sigacts_free(oldsigacts); 937 if (euip != NULL) 938 uifree(euip); 939 940 if (error && imgp->vmspace_destroyed) { 941 /* sorry, no more process anymore. exit gracefully */ 942 exit1(td, 0, SIGABRT); 943 /* NOT REACHED */ 944 } 945 946 #ifdef KTRACE 947 if (error == 0) 948 ktrprocctor(p); 949 #endif 950 951 /* 952 * We don't want cpu_set_syscall_retval() to overwrite any of 953 * the register values put in place by exec_setregs(). 954 * Implementations of cpu_set_syscall_retval() will leave 955 * registers unmodified when returning EJUSTRETURN. 956 */ 957 return (error == 0 ? EJUSTRETURN : error); 958 } 959 960 int 961 exec_map_first_page(struct image_params *imgp) 962 { 963 int rv, i, after, initial_pagein; 964 vm_page_t ma[VM_INITIAL_PAGEIN]; 965 vm_object_t object; 966 967 if (imgp->firstpage != NULL) 968 exec_unmap_first_page(imgp); 969 970 object = imgp->vp->v_object; 971 if (object == NULL) 972 return (EACCES); 973 VM_OBJECT_WLOCK(object); 974 #if VM_NRESERVLEVEL > 0 975 vm_object_color(object, 0); 976 #endif 977 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | 978 VM_ALLOC_WIRED); 979 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 980 vm_page_xbusy(ma[0]); 981 if (!vm_pager_has_page(object, 0, NULL, &after)) { 982 vm_page_lock(ma[0]); 983 vm_page_unwire_noq(ma[0]); 984 vm_page_free(ma[0]); 985 vm_page_unlock(ma[0]); 986 VM_OBJECT_WUNLOCK(object); 987 return (EIO); 988 } 989 initial_pagein = min(after, VM_INITIAL_PAGEIN); 990 KASSERT(initial_pagein <= object->size, 991 ("%s: initial_pagein %d object->size %ju", 992 __func__, initial_pagein, (uintmax_t )object->size)); 993 for (i = 1; i < initial_pagein; i++) { 994 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 995 if (ma[i]->valid) 996 break; 997 if (!vm_page_tryxbusy(ma[i])) 998 break; 999 } else { 1000 ma[i] = vm_page_alloc(object, i, 1001 VM_ALLOC_NORMAL); 1002 if (ma[i] == NULL) 1003 break; 1004 } 1005 } 1006 initial_pagein = i; 1007 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 1008 if (rv != VM_PAGER_OK) { 1009 for (i = 0; i < initial_pagein; i++) { 1010 vm_page_lock(ma[i]); 1011 if (i == 0) 1012 vm_page_unwire_noq(ma[i]); 1013 vm_page_free(ma[i]); 1014 vm_page_unlock(ma[i]); 1015 } 1016 VM_OBJECT_WUNLOCK(object); 1017 return (EIO); 1018 } 1019 vm_page_xunbusy(ma[0]); 1020 for (i = 1; i < initial_pagein; i++) 1021 vm_page_readahead_finish(ma[i]); 1022 } 1023 VM_OBJECT_WUNLOCK(object); 1024 1025 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1026 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1027 1028 return (0); 1029 } 1030 1031 void 1032 exec_unmap_first_page(struct image_params *imgp) 1033 { 1034 vm_page_t m; 1035 1036 if (imgp->firstpage != NULL) { 1037 m = sf_buf_page(imgp->firstpage); 1038 sf_buf_free(imgp->firstpage); 1039 imgp->firstpage = NULL; 1040 vm_page_lock(m); 1041 vm_page_unwire(m, PQ_ACTIVE); 1042 vm_page_unlock(m); 1043 } 1044 } 1045 1046 /* 1047 * Destroy old address space, and allocate a new stack. 1048 * The new stack is only sgrowsiz large because it is grown 1049 * automatically on a page fault. 1050 */ 1051 int 1052 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1053 { 1054 int error; 1055 struct proc *p = imgp->proc; 1056 struct vmspace *vmspace = p->p_vmspace; 1057 vm_object_t obj; 1058 struct rlimit rlim_stack; 1059 vm_offset_t sv_minuser, stack_addr; 1060 vm_map_t map; 1061 u_long ssiz; 1062 1063 imgp->vmspace_destroyed = 1; 1064 imgp->sysent = sv; 1065 1066 /* May be called with Giant held */ 1067 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1068 1069 /* 1070 * Blow away entire process VM, if address space not shared, 1071 * otherwise, create a new VM space so that other threads are 1072 * not disrupted 1073 */ 1074 map = &vmspace->vm_map; 1075 if (map_at_zero) 1076 sv_minuser = sv->sv_minuser; 1077 else 1078 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1079 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1080 vm_map_max(map) == sv->sv_maxuser && 1081 cpu_exec_vmspace_reuse(p, map)) { 1082 shmexit(vmspace); 1083 pmap_remove_pages(vmspace_pmap(vmspace)); 1084 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1085 /* 1086 * An exec terminates mlockall(MCL_FUTURE), ASLR state 1087 * must be re-evaluated. 1088 */ 1089 vm_map_lock(map); 1090 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1091 MAP_ASLR_IGNSTART); 1092 vm_map_unlock(map); 1093 } else { 1094 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1095 if (error) 1096 return (error); 1097 vmspace = p->p_vmspace; 1098 map = &vmspace->vm_map; 1099 } 1100 map->flags |= imgp->map_flags; 1101 1102 /* Map a shared page */ 1103 obj = sv->sv_shared_page_obj; 1104 if (obj != NULL) { 1105 vm_object_reference(obj); 1106 error = vm_map_fixed(map, obj, 0, 1107 sv->sv_shared_page_base, sv->sv_shared_page_len, 1108 VM_PROT_READ | VM_PROT_EXECUTE, 1109 VM_PROT_READ | VM_PROT_EXECUTE, 1110 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1111 if (error != KERN_SUCCESS) { 1112 vm_object_deallocate(obj); 1113 return (vm_mmap_to_errno(error)); 1114 } 1115 } 1116 1117 /* Allocate a new stack */ 1118 if (imgp->stack_sz != 0) { 1119 ssiz = trunc_page(imgp->stack_sz); 1120 PROC_LOCK(p); 1121 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1122 PROC_UNLOCK(p); 1123 if (ssiz > rlim_stack.rlim_max) 1124 ssiz = rlim_stack.rlim_max; 1125 if (ssiz > rlim_stack.rlim_cur) { 1126 rlim_stack.rlim_cur = ssiz; 1127 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1128 } 1129 } else if (sv->sv_maxssiz != NULL) { 1130 ssiz = *sv->sv_maxssiz; 1131 } else { 1132 ssiz = maxssiz; 1133 } 1134 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1135 if (ssiz < imgp->eff_stack_sz) 1136 imgp->eff_stack_sz = ssiz; 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, const char *fname, 1160 enum uio_seg segflg, char **argv, char **envv) 1161 { 1162 u_long arg, env; 1163 int error; 1164 1165 bzero(args, sizeof(*args)); 1166 if (argv == NULL) 1167 return (EFAULT); 1168 1169 /* 1170 * Allocate demand-paged memory for the file name, argument, and 1171 * environment strings. 1172 */ 1173 error = exec_alloc_args(args); 1174 if (error != 0) 1175 return (error); 1176 1177 /* 1178 * Copy the file name. 1179 */ 1180 error = exec_args_add_fname(args, fname, segflg); 1181 if (error != 0) 1182 goto err_exit; 1183 1184 /* 1185 * extract arguments first 1186 */ 1187 for (;;) { 1188 error = fueword(argv++, &arg); 1189 if (error == -1) { 1190 error = EFAULT; 1191 goto err_exit; 1192 } 1193 if (arg == 0) 1194 break; 1195 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1196 UIO_USERSPACE); 1197 if (error != 0) 1198 goto err_exit; 1199 } 1200 1201 /* 1202 * extract environment strings 1203 */ 1204 if (envv) { 1205 for (;;) { 1206 error = fueword(envv++, &env); 1207 if (error == -1) { 1208 error = EFAULT; 1209 goto err_exit; 1210 } 1211 if (env == 0) 1212 break; 1213 error = exec_args_add_env(args, 1214 (char *)(uintptr_t)env, UIO_USERSPACE); 1215 if (error != 0) 1216 goto err_exit; 1217 } 1218 } 1219 1220 return (0); 1221 1222 err_exit: 1223 exec_free_args(args); 1224 return (error); 1225 } 1226 1227 int 1228 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1229 const void *data, size_t datalen, const int *fds, size_t fdslen) 1230 { 1231 struct filedesc *ofdp; 1232 const char *p; 1233 int *kfds; 1234 int error; 1235 1236 memset(args, '\0', sizeof(*args)); 1237 ofdp = td->td_proc->p_fd; 1238 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1239 return (E2BIG); 1240 error = exec_alloc_args(args); 1241 if (error != 0) 1242 return (error); 1243 1244 args->begin_argv = args->buf; 1245 args->stringspace = ARG_MAX; 1246 1247 if (datalen > 0) { 1248 /* 1249 * Argument buffer has been provided. Copy it into the 1250 * kernel as a single string and add a terminating null 1251 * byte. 1252 */ 1253 error = copyin(data, args->begin_argv, datalen); 1254 if (error != 0) 1255 goto err_exit; 1256 args->begin_argv[datalen] = '\0'; 1257 args->endp = args->begin_argv + datalen + 1; 1258 args->stringspace -= datalen + 1; 1259 1260 /* 1261 * Traditional argument counting. Count the number of 1262 * null bytes. 1263 */ 1264 for (p = args->begin_argv; p < args->endp; ++p) 1265 if (*p == '\0') 1266 ++args->argc; 1267 } else { 1268 /* No argument buffer provided. */ 1269 args->endp = args->begin_argv; 1270 } 1271 1272 /* Create new file descriptor table. */ 1273 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1274 error = copyin(fds, kfds, fdslen * sizeof(int)); 1275 if (error != 0) { 1276 free(kfds, M_TEMP); 1277 goto err_exit; 1278 } 1279 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1280 free(kfds, M_TEMP); 1281 if (error != 0) 1282 goto err_exit; 1283 1284 return (0); 1285 err_exit: 1286 exec_free_args(args); 1287 return (error); 1288 } 1289 1290 struct exec_args_kva { 1291 vm_offset_t addr; 1292 u_int gen; 1293 SLIST_ENTRY(exec_args_kva) next; 1294 }; 1295 1296 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1297 1298 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1299 static struct mtx exec_args_kva_mtx; 1300 static u_int exec_args_gen; 1301 1302 static void 1303 exec_prealloc_args_kva(void *arg __unused) 1304 { 1305 struct exec_args_kva *argkva; 1306 u_int i; 1307 1308 SLIST_INIT(&exec_args_kva_freelist); 1309 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1310 for (i = 0; i < exec_map_entries; i++) { 1311 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1312 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1313 argkva->gen = exec_args_gen; 1314 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1315 } 1316 } 1317 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1318 1319 static vm_offset_t 1320 exec_alloc_args_kva(void **cookie) 1321 { 1322 struct exec_args_kva *argkva; 1323 1324 argkva = (void *)atomic_readandclear_ptr( 1325 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1326 if (argkva == NULL) { 1327 mtx_lock(&exec_args_kva_mtx); 1328 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1329 (void)mtx_sleep(&exec_args_kva_freelist, 1330 &exec_args_kva_mtx, 0, "execkva", 0); 1331 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1332 mtx_unlock(&exec_args_kva_mtx); 1333 } 1334 *(struct exec_args_kva **)cookie = argkva; 1335 return (argkva->addr); 1336 } 1337 1338 static void 1339 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1340 { 1341 vm_offset_t base; 1342 1343 base = argkva->addr; 1344 if (argkva->gen != gen) { 1345 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1346 MADV_FREE); 1347 argkva->gen = gen; 1348 } 1349 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1350 (uintptr_t)NULL, (uintptr_t)argkva)) { 1351 mtx_lock(&exec_args_kva_mtx); 1352 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1353 wakeup_one(&exec_args_kva_freelist); 1354 mtx_unlock(&exec_args_kva_mtx); 1355 } 1356 } 1357 1358 static void 1359 exec_free_args_kva(void *cookie) 1360 { 1361 1362 exec_release_args_kva(cookie, exec_args_gen); 1363 } 1364 1365 static void 1366 exec_args_kva_lowmem(void *arg __unused) 1367 { 1368 SLIST_HEAD(, exec_args_kva) head; 1369 struct exec_args_kva *argkva; 1370 u_int gen; 1371 int i; 1372 1373 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1374 1375 /* 1376 * Force an madvise of each KVA range. Any currently allocated ranges 1377 * will have MADV_FREE applied once they are freed. 1378 */ 1379 SLIST_INIT(&head); 1380 mtx_lock(&exec_args_kva_mtx); 1381 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1382 mtx_unlock(&exec_args_kva_mtx); 1383 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1384 SLIST_REMOVE_HEAD(&head, next); 1385 exec_release_args_kva(argkva, gen); 1386 } 1387 1388 CPU_FOREACH(i) { 1389 argkva = (void *)atomic_readandclear_ptr( 1390 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1391 if (argkva != NULL) 1392 exec_release_args_kva(argkva, gen); 1393 } 1394 } 1395 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1396 EVENTHANDLER_PRI_ANY); 1397 1398 /* 1399 * Allocate temporary demand-paged, zero-filled memory for the file name, 1400 * argument, and environment strings. 1401 */ 1402 int 1403 exec_alloc_args(struct image_args *args) 1404 { 1405 1406 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1407 return (0); 1408 } 1409 1410 void 1411 exec_free_args(struct image_args *args) 1412 { 1413 1414 if (args->buf != NULL) { 1415 exec_free_args_kva(args->bufkva); 1416 args->buf = NULL; 1417 } 1418 if (args->fname_buf != NULL) { 1419 free(args->fname_buf, M_TEMP); 1420 args->fname_buf = NULL; 1421 } 1422 if (args->fdp != NULL) 1423 fdescfree_remapped(args->fdp); 1424 } 1425 1426 /* 1427 * A set to functions to fill struct image args. 1428 * 1429 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1430 * fname) before the other functions. All exec_args_add_arg() calls must 1431 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1432 * may be called any time after exec_args_add_fname(). 1433 * 1434 * exec_args_add_fname() - install path to be executed 1435 * exec_args_add_arg() - append an argument string 1436 * exec_args_add_env() - append an env string 1437 * exec_args_adjust_args() - adjust location of the argument list to 1438 * allow new arguments to be prepended 1439 */ 1440 int 1441 exec_args_add_fname(struct image_args *args, const char *fname, 1442 enum uio_seg segflg) 1443 { 1444 int error; 1445 size_t length; 1446 1447 KASSERT(args->fname == NULL, ("fname already appended")); 1448 KASSERT(args->endp == NULL, ("already appending to args")); 1449 1450 if (fname != NULL) { 1451 args->fname = args->buf; 1452 error = segflg == UIO_SYSSPACE ? 1453 copystr(fname, args->fname, PATH_MAX, &length) : 1454 copyinstr(fname, args->fname, PATH_MAX, &length); 1455 if (error != 0) 1456 return (error == ENAMETOOLONG ? E2BIG : error); 1457 } else 1458 length = 0; 1459 1460 /* Set up for _arg_*()/_env_*() */ 1461 args->endp = args->buf + length; 1462 /* begin_argv must be set and kept updated */ 1463 args->begin_argv = args->endp; 1464 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1465 ("too little space remaining for arguments %zu < %zu", 1466 exec_map_entry_size - length, (size_t)ARG_MAX)); 1467 args->stringspace = ARG_MAX; 1468 1469 return (0); 1470 } 1471 1472 static int 1473 exec_args_add_str(struct image_args *args, const char *str, 1474 enum uio_seg segflg, int *countp) 1475 { 1476 int error; 1477 size_t length; 1478 1479 KASSERT(args->endp != NULL, ("endp not initialized")); 1480 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1481 1482 error = (segflg == UIO_SYSSPACE) ? 1483 copystr(str, args->endp, args->stringspace, &length) : 1484 copyinstr(str, args->endp, args->stringspace, &length); 1485 if (error != 0) 1486 return (error == ENAMETOOLONG ? E2BIG : error); 1487 args->stringspace -= length; 1488 args->endp += length; 1489 (*countp)++; 1490 1491 return (0); 1492 } 1493 1494 int 1495 exec_args_add_arg(struct image_args *args, const char *argp, 1496 enum uio_seg segflg) 1497 { 1498 1499 KASSERT(args->envc == 0, ("appending args after env")); 1500 1501 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1502 } 1503 1504 int 1505 exec_args_add_env(struct image_args *args, const char *envp, 1506 enum uio_seg segflg) 1507 { 1508 1509 if (args->envc == 0) 1510 args->begin_envv = args->endp; 1511 1512 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1513 } 1514 1515 int 1516 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1517 { 1518 ssize_t offset; 1519 1520 KASSERT(args->endp != NULL, ("endp not initialized")); 1521 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1522 1523 offset = extend - consume; 1524 if (args->stringspace < offset) 1525 return (E2BIG); 1526 memmove(args->begin_argv + extend, args->begin_argv + consume, 1527 args->endp - args->begin_argv + consume); 1528 if (args->envc > 0) 1529 args->begin_envv += offset; 1530 args->endp += offset; 1531 args->stringspace -= offset; 1532 return (0); 1533 } 1534 1535 char * 1536 exec_args_get_begin_envv(struct image_args *args) 1537 { 1538 1539 KASSERT(args->endp != NULL, ("endp not initialized")); 1540 1541 if (args->envc > 0) 1542 return (args->begin_envv); 1543 return (args->endp); 1544 } 1545 1546 /* 1547 * Copy strings out to the new process address space, constructing new arg 1548 * and env vector tables. Return a pointer to the base so that it can be used 1549 * as the initial stack pointer. 1550 */ 1551 register_t * 1552 exec_copyout_strings(struct image_params *imgp) 1553 { 1554 int argc, envc; 1555 char **vectp; 1556 char *stringp; 1557 uintptr_t destp; 1558 register_t *stack_base; 1559 struct ps_strings *arginfo; 1560 struct proc *p; 1561 size_t execpath_len; 1562 int szsigcode, szps; 1563 char canary[sizeof(long) * 8]; 1564 1565 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1566 /* 1567 * Calculate string base and vector table pointers. 1568 * Also deal with signal trampoline code for this exec type. 1569 */ 1570 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1571 execpath_len = strlen(imgp->execpath) + 1; 1572 else 1573 execpath_len = 0; 1574 p = imgp->proc; 1575 szsigcode = 0; 1576 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1577 if (p->p_sysent->sv_sigcode_base == 0) { 1578 if (p->p_sysent->sv_szsigcode != NULL) 1579 szsigcode = *(p->p_sysent->sv_szsigcode); 1580 } 1581 destp = (uintptr_t)arginfo; 1582 1583 /* 1584 * install sigcode 1585 */ 1586 if (szsigcode != 0) { 1587 destp -= szsigcode; 1588 destp = rounddown2(destp, sizeof(void *)); 1589 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1590 } 1591 1592 /* 1593 * Copy the image path for the rtld. 1594 */ 1595 if (execpath_len != 0) { 1596 destp -= execpath_len; 1597 destp = rounddown2(destp, sizeof(void *)); 1598 imgp->execpathp = destp; 1599 copyout(imgp->execpath, (void *)destp, execpath_len); 1600 } 1601 1602 /* 1603 * Prepare the canary for SSP. 1604 */ 1605 arc4rand(canary, sizeof(canary), 0); 1606 destp -= sizeof(canary); 1607 imgp->canary = destp; 1608 copyout(canary, (void *)destp, sizeof(canary)); 1609 imgp->canarylen = sizeof(canary); 1610 1611 /* 1612 * Prepare the pagesizes array. 1613 */ 1614 destp -= szps; 1615 destp = rounddown2(destp, sizeof(void *)); 1616 imgp->pagesizes = destp; 1617 copyout(pagesizes, (void *)destp, szps); 1618 imgp->pagesizeslen = szps; 1619 1620 destp -= ARG_MAX - imgp->args->stringspace; 1621 destp = rounddown2(destp, sizeof(void *)); 1622 1623 vectp = (char **)destp; 1624 if (imgp->sysent->sv_stackgap != NULL) 1625 imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); 1626 1627 if (imgp->auxargs) { 1628 /* 1629 * Allocate room on the stack for the ELF auxargs 1630 * array. It has up to AT_COUNT entries. 1631 */ 1632 vectp -= howmany(AT_COUNT * sizeof(Elf_Auxinfo), 1633 sizeof(*vectp)); 1634 } 1635 1636 /* 1637 * Allocate room for the argv[] and env vectors including the 1638 * terminating NULL pointers. 1639 */ 1640 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1641 1642 /* 1643 * vectp also becomes our initial stack base 1644 */ 1645 stack_base = (register_t *)vectp; 1646 1647 stringp = imgp->args->begin_argv; 1648 argc = imgp->args->argc; 1649 envc = imgp->args->envc; 1650 1651 /* 1652 * Copy out strings - arguments and environment. 1653 */ 1654 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1655 1656 /* 1657 * Fill in "ps_strings" struct for ps, w, etc. 1658 */ 1659 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1660 suword32(&arginfo->ps_nargvstr, argc); 1661 1662 /* 1663 * Fill in argument portion of vector table. 1664 */ 1665 for (; argc > 0; --argc) { 1666 suword(vectp++, (long)(intptr_t)destp); 1667 while (*stringp++ != 0) 1668 destp++; 1669 destp++; 1670 } 1671 1672 /* a null vector table pointer separates the argp's from the envp's */ 1673 suword(vectp++, 0); 1674 1675 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1676 suword32(&arginfo->ps_nenvstr, envc); 1677 1678 /* 1679 * Fill in environment portion of vector table. 1680 */ 1681 for (; envc > 0; --envc) { 1682 suword(vectp++, (long)(intptr_t)destp); 1683 while (*stringp++ != 0) 1684 destp++; 1685 destp++; 1686 } 1687 1688 /* end of vector table is a null pointer */ 1689 suword(vectp, 0); 1690 1691 return (stack_base); 1692 } 1693 1694 /* 1695 * Check permissions of file to execute. 1696 * Called with imgp->vp locked. 1697 * Return 0 for success or error code on failure. 1698 */ 1699 int 1700 exec_check_permissions(struct image_params *imgp) 1701 { 1702 struct vnode *vp = imgp->vp; 1703 struct vattr *attr = imgp->attr; 1704 struct thread *td; 1705 int error; 1706 1707 td = curthread; 1708 1709 /* Get file attributes */ 1710 error = VOP_GETATTR(vp, attr, td->td_ucred); 1711 if (error) 1712 return (error); 1713 1714 #ifdef MAC 1715 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1716 if (error) 1717 return (error); 1718 #endif 1719 1720 /* 1721 * 1) Check if file execution is disabled for the filesystem that 1722 * this file resides on. 1723 * 2) Ensure that at least one execute bit is on. Otherwise, a 1724 * privileged user will always succeed, and we don't want this 1725 * to happen unless the file really is executable. 1726 * 3) Ensure that the file is a regular file. 1727 */ 1728 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1729 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1730 (attr->va_type != VREG)) 1731 return (EACCES); 1732 1733 /* 1734 * Zero length files can't be exec'd 1735 */ 1736 if (attr->va_size == 0) 1737 return (ENOEXEC); 1738 1739 /* 1740 * Check for execute permission to file based on current credentials. 1741 */ 1742 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1743 if (error) 1744 return (error); 1745 1746 /* 1747 * Check number of open-for-writes on the file and deny execution 1748 * if there are any. 1749 * 1750 * Add a text reference now so no one can write to the 1751 * executable while we're activating it. 1752 * 1753 * Remember if this was set before and unset it in case this is not 1754 * actually an executable image. 1755 */ 1756 error = VOP_SET_TEXT(vp); 1757 if (error != 0) 1758 return (error); 1759 imgp->textset = true; 1760 1761 /* 1762 * Call filesystem specific open routine (which does nothing in the 1763 * general case). 1764 */ 1765 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1766 if (error == 0) 1767 imgp->opened = 1; 1768 return (error); 1769 } 1770 1771 /* 1772 * Exec handler registration 1773 */ 1774 int 1775 exec_register(const struct execsw *execsw_arg) 1776 { 1777 const struct execsw **es, **xs, **newexecsw; 1778 u_int count = 2; /* New slot and trailing NULL */ 1779 1780 if (execsw) 1781 for (es = execsw; *es; es++) 1782 count++; 1783 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1784 xs = newexecsw; 1785 if (execsw) 1786 for (es = execsw; *es; es++) 1787 *xs++ = *es; 1788 *xs++ = execsw_arg; 1789 *xs = NULL; 1790 if (execsw) 1791 free(execsw, M_TEMP); 1792 execsw = newexecsw; 1793 return (0); 1794 } 1795 1796 int 1797 exec_unregister(const struct execsw *execsw_arg) 1798 { 1799 const struct execsw **es, **xs, **newexecsw; 1800 int count = 1; 1801 1802 if (execsw == NULL) 1803 panic("unregister with no handlers left?\n"); 1804 1805 for (es = execsw; *es; es++) { 1806 if (*es == execsw_arg) 1807 break; 1808 } 1809 if (*es == NULL) 1810 return (ENOENT); 1811 for (es = execsw; *es; es++) 1812 if (*es != execsw_arg) 1813 count++; 1814 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1815 xs = newexecsw; 1816 for (es = execsw; *es; es++) 1817 if (*es != execsw_arg) 1818 *xs++ = *es; 1819 *xs = NULL; 1820 if (execsw) 1821 free(execsw, M_TEMP); 1822 execsw = newexecsw; 1823 return (0); 1824 } 1825