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_SHARED | 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_SHARED | 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_SHARED | 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 MPASS(imgp->textset); 620 VOP_UNSET_TEXT_CHECKED(newtextvp); 621 imgp->textset = false; 622 /* free name buffer and old vnode */ 623 if (args->fname != NULL) 624 NDFREE(&nd, NDF_ONLY_PNBUF); 625 #ifdef MAC 626 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 627 #endif 628 if (imgp->opened) { 629 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 630 imgp->opened = 0; 631 } 632 vput(newtextvp); 633 vm_object_deallocate(imgp->object); 634 imgp->object = NULL; 635 imgp->credential_setid = false; 636 if (imgp->newcred != NULL) { 637 crfree(imgp->newcred); 638 imgp->newcred = NULL; 639 } 640 imgp->execpath = NULL; 641 free(imgp->freepath, M_TEMP); 642 imgp->freepath = NULL; 643 /* set new name to that of the interpreter */ 644 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME, 645 UIO_SYSSPACE, imgp->interpreter_name, td); 646 args->fname = imgp->interpreter_name; 647 goto interpret; 648 } 649 650 /* 651 * NB: We unlock the vnode here because it is believed that none 652 * of the sv_copyout_strings/sv_fixup operations require the vnode. 653 */ 654 VOP_UNLOCK(imgp->vp, 0); 655 656 if (disallow_high_osrel && 657 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 658 error = ENOEXEC; 659 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 660 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 661 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 662 goto exec_fail_dealloc; 663 } 664 665 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 666 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 667 sys_cap_enter(td, NULL); 668 669 /* 670 * Copy out strings (args and env) and initialize stack base. 671 */ 672 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 673 674 /* 675 * Stack setup. 676 */ 677 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 678 if (error != 0) { 679 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 680 goto exec_fail_dealloc; 681 } 682 683 if (args->fdp != NULL) { 684 /* Install a brand new file descriptor table. */ 685 fdinstall_remapped(td, args->fdp); 686 args->fdp = NULL; 687 } else { 688 /* 689 * Keep on using the existing file descriptor table. For 690 * security and other reasons, the file descriptor table 691 * cannot be shared after an exec. 692 */ 693 fdunshare(td); 694 /* close files on exec */ 695 fdcloseexec(td); 696 } 697 698 /* 699 * Malloc things before we need locks. 700 */ 701 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 702 /* Cache arguments if they fit inside our allowance */ 703 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 704 newargs = pargs_alloc(i); 705 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 706 } 707 708 /* 709 * For security and other reasons, signal handlers cannot 710 * be shared after an exec. The new process gets a copy of the old 711 * handlers. In execsigs(), the new process will have its signals 712 * reset. 713 */ 714 if (sigacts_shared(p->p_sigacts)) { 715 oldsigacts = p->p_sigacts; 716 newsigacts = sigacts_alloc(); 717 sigacts_copy(newsigacts, oldsigacts); 718 } 719 720 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 721 722 PROC_LOCK(p); 723 if (oldsigacts) 724 p->p_sigacts = newsigacts; 725 /* Stop profiling */ 726 stopprofclock(p); 727 728 /* reset caught signals */ 729 execsigs(p); 730 731 /* name this process - nameiexec(p, ndp) */ 732 bzero(p->p_comm, sizeof(p->p_comm)); 733 if (args->fname) 734 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 735 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 736 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 737 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 738 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 739 #ifdef KTR 740 sched_clear_tdname(td); 741 #endif 742 743 /* 744 * mark as execed, wakeup the process that vforked (if any) and tell 745 * it that it now has its own resources back 746 */ 747 p->p_flag |= P_EXEC; 748 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 749 p->p_flag2 &= ~P2_NOTRACE; 750 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 751 p->p_flag2 &= ~P2_STKGAP_DISABLE; 752 if (p->p_flag & P_PPWAIT) { 753 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 754 cv_broadcast(&p->p_pwait); 755 /* STOPs are no longer ignored, arrange for AST */ 756 signotify(td); 757 } 758 759 /* 760 * Implement image setuid/setgid installation. 761 */ 762 if (imgp->credential_setid) { 763 /* 764 * Turn off syscall tracing for set-id programs, except for 765 * root. Record any set-id flags first to make sure that 766 * we do not regain any tracing during a possible block. 767 */ 768 setsugid(p); 769 770 #ifdef KTRACE 771 if (p->p_tracecred != NULL && 772 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED)) 773 ktrprocexec(p, &tracecred, &tracevp); 774 #endif 775 /* 776 * Close any file descriptors 0..2 that reference procfs, 777 * then make sure file descriptors 0..2 are in use. 778 * 779 * Both fdsetugidsafety() and fdcheckstd() may call functions 780 * taking sleepable locks, so temporarily drop our locks. 781 */ 782 PROC_UNLOCK(p); 783 VOP_UNLOCK(imgp->vp, 0); 784 fdsetugidsafety(td); 785 error = fdcheckstd(td); 786 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 787 if (error != 0) 788 goto exec_fail_dealloc; 789 PROC_LOCK(p); 790 #ifdef MAC 791 if (will_transition) { 792 mac_vnode_execve_transition(oldcred, imgp->newcred, 793 imgp->vp, interpvplabel, imgp); 794 } 795 #endif 796 } else { 797 if (oldcred->cr_uid == oldcred->cr_ruid && 798 oldcred->cr_gid == oldcred->cr_rgid) 799 p->p_flag &= ~P_SUGID; 800 } 801 /* 802 * Set the new credentials. 803 */ 804 if (imgp->newcred != NULL) { 805 proc_set_cred(p, imgp->newcred); 806 crfree(oldcred); 807 oldcred = NULL; 808 } 809 810 /* 811 * Store the vp for use in procfs. This vnode was referenced by namei 812 * or fgetvp_exec. 813 */ 814 oldtextvp = p->p_textvp; 815 p->p_textvp = newtextvp; 816 817 #ifdef KDTRACE_HOOKS 818 /* 819 * Tell the DTrace fasttrap provider about the exec if it 820 * has declared an interest. 821 */ 822 if (dtrace_fasttrap_exec) 823 dtrace_fasttrap_exec(p); 824 #endif 825 826 /* 827 * Notify others that we exec'd, and clear the P_INEXEC flag 828 * as we're now a bona fide freshly-execed process. 829 */ 830 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 831 p->p_flag &= ~P_INEXEC; 832 833 /* clear "fork but no exec" flag, as we _are_ execing */ 834 p->p_acflag &= ~AFORK; 835 836 /* 837 * Free any previous argument cache and replace it with 838 * the new argument cache, if any. 839 */ 840 oldargs = p->p_args; 841 p->p_args = newargs; 842 newargs = NULL; 843 844 PROC_UNLOCK(p); 845 846 #ifdef HWPMC_HOOKS 847 /* 848 * Check if system-wide sampling is in effect or if the 849 * current process is using PMCs. If so, do exec() time 850 * processing. This processing needs to happen AFTER the 851 * P_INEXEC flag is cleared. 852 */ 853 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 854 VOP_UNLOCK(imgp->vp, 0); 855 pe.pm_credentialschanged = credential_changing; 856 pe.pm_entryaddr = imgp->entry_addr; 857 858 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 859 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 860 } 861 #endif 862 863 /* Set values passed into the program in registers. */ 864 (*p->p_sysent->sv_setregs)(td, imgp, (u_long)(uintptr_t)stack_base); 865 866 vfs_mark_atime(imgp->vp, td->td_ucred); 867 868 SDT_PROBE1(proc, , , exec__success, args->fname); 869 870 exec_fail_dealloc: 871 if (imgp->firstpage != NULL) 872 exec_unmap_first_page(imgp); 873 874 if (imgp->vp != NULL) { 875 if (args->fname) 876 NDFREE(&nd, NDF_ONLY_PNBUF); 877 if (imgp->opened) 878 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 879 if (imgp->textset) 880 VOP_UNSET_TEXT_CHECKED(imgp->vp); 881 if (error != 0) 882 vput(imgp->vp); 883 else 884 VOP_UNLOCK(imgp->vp, 0); 885 } 886 887 if (imgp->object != NULL) 888 vm_object_deallocate(imgp->object); 889 890 free(imgp->freepath, M_TEMP); 891 892 if (error == 0) { 893 if (p->p_ptevents & PTRACE_EXEC) { 894 PROC_LOCK(p); 895 if (p->p_ptevents & PTRACE_EXEC) 896 td->td_dbgflags |= TDB_EXEC; 897 PROC_UNLOCK(p); 898 } 899 900 /* 901 * Stop the process here if its stop event mask has 902 * the S_EXEC bit set. 903 */ 904 STOPEVENT(p, S_EXEC, 0); 905 } else { 906 exec_fail: 907 /* we're done here, clear P_INEXEC */ 908 PROC_LOCK(p); 909 p->p_flag &= ~P_INEXEC; 910 PROC_UNLOCK(p); 911 912 SDT_PROBE1(proc, , , exec__failure, error); 913 } 914 915 if (imgp->newcred != NULL && oldcred != NULL) 916 crfree(imgp->newcred); 917 918 #ifdef MAC 919 mac_execve_exit(imgp); 920 mac_execve_interpreter_exit(interpvplabel); 921 #endif 922 exec_free_args(args); 923 924 /* 925 * Handle deferred decrement of ref counts. 926 */ 927 if (oldtextvp != NULL) 928 vrele(oldtextvp); 929 #ifdef KTRACE 930 if (tracevp != NULL) 931 vrele(tracevp); 932 if (tracecred != NULL) 933 crfree(tracecred); 934 #endif 935 pargs_drop(oldargs); 936 pargs_drop(newargs); 937 if (oldsigacts != NULL) 938 sigacts_free(oldsigacts); 939 if (euip != NULL) 940 uifree(euip); 941 942 if (error && imgp->vmspace_destroyed) { 943 /* sorry, no more process anymore. exit gracefully */ 944 exit1(td, 0, SIGABRT); 945 /* NOT REACHED */ 946 } 947 948 #ifdef KTRACE 949 if (error == 0) 950 ktrprocctor(p); 951 #endif 952 953 /* 954 * We don't want cpu_set_syscall_retval() to overwrite any of 955 * the register values put in place by exec_setregs(). 956 * Implementations of cpu_set_syscall_retval() will leave 957 * registers unmodified when returning EJUSTRETURN. 958 */ 959 return (error == 0 ? EJUSTRETURN : error); 960 } 961 962 int 963 exec_map_first_page(struct image_params *imgp) 964 { 965 int rv, i, after, initial_pagein; 966 vm_page_t ma[VM_INITIAL_PAGEIN]; 967 vm_object_t object; 968 969 if (imgp->firstpage != NULL) 970 exec_unmap_first_page(imgp); 971 972 object = imgp->vp->v_object; 973 if (object == NULL) 974 return (EACCES); 975 VM_OBJECT_WLOCK(object); 976 #if VM_NRESERVLEVEL > 0 977 vm_object_color(object, 0); 978 #endif 979 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | 980 VM_ALLOC_WIRED); 981 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 982 vm_page_xbusy(ma[0]); 983 if (!vm_pager_has_page(object, 0, NULL, &after)) { 984 if (vm_page_unwire_noq(ma[0])) 985 vm_page_free(ma[0]); 986 else 987 vm_page_xunbusy(ma[0]); 988 VM_OBJECT_WUNLOCK(object); 989 return (EIO); 990 } 991 initial_pagein = min(after, VM_INITIAL_PAGEIN); 992 KASSERT(initial_pagein <= object->size, 993 ("%s: initial_pagein %d object->size %ju", 994 __func__, initial_pagein, (uintmax_t )object->size)); 995 for (i = 1; i < initial_pagein; i++) { 996 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 997 if (ma[i]->valid) 998 break; 999 if (!vm_page_tryxbusy(ma[i])) 1000 break; 1001 } else { 1002 ma[i] = vm_page_alloc(object, i, 1003 VM_ALLOC_NORMAL); 1004 if (ma[i] == NULL) 1005 break; 1006 } 1007 } 1008 initial_pagein = i; 1009 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 1010 if (rv != VM_PAGER_OK) { 1011 if (vm_page_unwire_noq(ma[0])) 1012 vm_page_free(ma[0]); 1013 else 1014 vm_page_xunbusy(ma[0]); 1015 for (i = 1; i < initial_pagein; i++) { 1016 if (!vm_page_wired(ma[i])) 1017 vm_page_free(ma[i]); 1018 else 1019 vm_page_xunbusy(ma[i]); 1020 } 1021 VM_OBJECT_WUNLOCK(object); 1022 return (EIO); 1023 } 1024 vm_page_xunbusy(ma[0]); 1025 for (i = 1; i < initial_pagein; i++) 1026 vm_page_readahead_finish(ma[i]); 1027 } 1028 VM_OBJECT_WUNLOCK(object); 1029 1030 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1031 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1032 1033 return (0); 1034 } 1035 1036 void 1037 exec_unmap_first_page(struct image_params *imgp) 1038 { 1039 vm_page_t m; 1040 1041 if (imgp->firstpage != NULL) { 1042 m = sf_buf_page(imgp->firstpage); 1043 sf_buf_free(imgp->firstpage); 1044 imgp->firstpage = NULL; 1045 vm_page_unwire(m, PQ_ACTIVE); 1046 } 1047 } 1048 1049 /* 1050 * Destroy old address space, and allocate a new stack. 1051 * The new stack is only sgrowsiz large because it is grown 1052 * automatically on a page fault. 1053 */ 1054 int 1055 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1056 { 1057 int error; 1058 struct proc *p = imgp->proc; 1059 struct vmspace *vmspace = p->p_vmspace; 1060 vm_object_t obj; 1061 struct rlimit rlim_stack; 1062 vm_offset_t sv_minuser, stack_addr; 1063 vm_map_t map; 1064 u_long ssiz; 1065 1066 imgp->vmspace_destroyed = 1; 1067 imgp->sysent = sv; 1068 1069 /* May be called with Giant held */ 1070 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1071 1072 /* 1073 * Blow away entire process VM, if address space not shared, 1074 * otherwise, create a new VM space so that other threads are 1075 * not disrupted 1076 */ 1077 map = &vmspace->vm_map; 1078 if (map_at_zero) 1079 sv_minuser = sv->sv_minuser; 1080 else 1081 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1082 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1083 vm_map_max(map) == sv->sv_maxuser && 1084 cpu_exec_vmspace_reuse(p, map)) { 1085 shmexit(vmspace); 1086 pmap_remove_pages(vmspace_pmap(vmspace)); 1087 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1088 /* 1089 * An exec terminates mlockall(MCL_FUTURE), ASLR state 1090 * must be re-evaluated. 1091 */ 1092 vm_map_lock(map); 1093 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1094 MAP_ASLR_IGNSTART); 1095 vm_map_unlock(map); 1096 } else { 1097 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1098 if (error) 1099 return (error); 1100 vmspace = p->p_vmspace; 1101 map = &vmspace->vm_map; 1102 } 1103 map->flags |= imgp->map_flags; 1104 1105 /* Map a shared page */ 1106 obj = sv->sv_shared_page_obj; 1107 if (obj != NULL) { 1108 vm_object_reference(obj); 1109 error = vm_map_fixed(map, obj, 0, 1110 sv->sv_shared_page_base, sv->sv_shared_page_len, 1111 VM_PROT_READ | VM_PROT_EXECUTE, 1112 VM_PROT_READ | VM_PROT_EXECUTE, 1113 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1114 if (error != KERN_SUCCESS) { 1115 vm_object_deallocate(obj); 1116 return (vm_mmap_to_errno(error)); 1117 } 1118 } 1119 1120 /* Allocate a new stack */ 1121 if (imgp->stack_sz != 0) { 1122 ssiz = trunc_page(imgp->stack_sz); 1123 PROC_LOCK(p); 1124 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1125 PROC_UNLOCK(p); 1126 if (ssiz > rlim_stack.rlim_max) 1127 ssiz = rlim_stack.rlim_max; 1128 if (ssiz > rlim_stack.rlim_cur) { 1129 rlim_stack.rlim_cur = ssiz; 1130 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1131 } 1132 } else if (sv->sv_maxssiz != NULL) { 1133 ssiz = *sv->sv_maxssiz; 1134 } else { 1135 ssiz = maxssiz; 1136 } 1137 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1138 if (ssiz < imgp->eff_stack_sz) 1139 imgp->eff_stack_sz = ssiz; 1140 stack_addr = sv->sv_usrstack - ssiz; 1141 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1142 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1143 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1144 if (error != KERN_SUCCESS) 1145 return (vm_mmap_to_errno(error)); 1146 1147 /* 1148 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1149 * are still used to enforce the stack rlimit on the process stack. 1150 */ 1151 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1152 vmspace->vm_maxsaddr = (char *)stack_addr; 1153 1154 return (0); 1155 } 1156 1157 /* 1158 * Copy out argument and environment strings from the old process address 1159 * space into the temporary string buffer. 1160 */ 1161 int 1162 exec_copyin_args(struct image_args *args, const char *fname, 1163 enum uio_seg segflg, char **argv, char **envv) 1164 { 1165 u_long arg, env; 1166 int error; 1167 1168 bzero(args, sizeof(*args)); 1169 if (argv == NULL) 1170 return (EFAULT); 1171 1172 /* 1173 * Allocate demand-paged memory for the file name, argument, and 1174 * environment strings. 1175 */ 1176 error = exec_alloc_args(args); 1177 if (error != 0) 1178 return (error); 1179 1180 /* 1181 * Copy the file name. 1182 */ 1183 error = exec_args_add_fname(args, fname, segflg); 1184 if (error != 0) 1185 goto err_exit; 1186 1187 /* 1188 * extract arguments first 1189 */ 1190 for (;;) { 1191 error = fueword(argv++, &arg); 1192 if (error == -1) { 1193 error = EFAULT; 1194 goto err_exit; 1195 } 1196 if (arg == 0) 1197 break; 1198 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1199 UIO_USERSPACE); 1200 if (error != 0) 1201 goto err_exit; 1202 } 1203 1204 /* 1205 * extract environment strings 1206 */ 1207 if (envv) { 1208 for (;;) { 1209 error = fueword(envv++, &env); 1210 if (error == -1) { 1211 error = EFAULT; 1212 goto err_exit; 1213 } 1214 if (env == 0) 1215 break; 1216 error = exec_args_add_env(args, 1217 (char *)(uintptr_t)env, UIO_USERSPACE); 1218 if (error != 0) 1219 goto err_exit; 1220 } 1221 } 1222 1223 return (0); 1224 1225 err_exit: 1226 exec_free_args(args); 1227 return (error); 1228 } 1229 1230 int 1231 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1232 const void *data, size_t datalen, const int *fds, size_t fdslen) 1233 { 1234 struct filedesc *ofdp; 1235 const char *p; 1236 int *kfds; 1237 int error; 1238 1239 memset(args, '\0', sizeof(*args)); 1240 ofdp = td->td_proc->p_fd; 1241 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1242 return (E2BIG); 1243 error = exec_alloc_args(args); 1244 if (error != 0) 1245 return (error); 1246 1247 args->begin_argv = args->buf; 1248 args->stringspace = ARG_MAX; 1249 1250 if (datalen > 0) { 1251 /* 1252 * Argument buffer has been provided. Copy it into the 1253 * kernel as a single string and add a terminating null 1254 * byte. 1255 */ 1256 error = copyin(data, args->begin_argv, datalen); 1257 if (error != 0) 1258 goto err_exit; 1259 args->begin_argv[datalen] = '\0'; 1260 args->endp = args->begin_argv + datalen + 1; 1261 args->stringspace -= datalen + 1; 1262 1263 /* 1264 * Traditional argument counting. Count the number of 1265 * null bytes. 1266 */ 1267 for (p = args->begin_argv; p < args->endp; ++p) 1268 if (*p == '\0') 1269 ++args->argc; 1270 } else { 1271 /* No argument buffer provided. */ 1272 args->endp = args->begin_argv; 1273 } 1274 1275 /* Create new file descriptor table. */ 1276 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1277 error = copyin(fds, kfds, fdslen * sizeof(int)); 1278 if (error != 0) { 1279 free(kfds, M_TEMP); 1280 goto err_exit; 1281 } 1282 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1283 free(kfds, M_TEMP); 1284 if (error != 0) 1285 goto err_exit; 1286 1287 return (0); 1288 err_exit: 1289 exec_free_args(args); 1290 return (error); 1291 } 1292 1293 struct exec_args_kva { 1294 vm_offset_t addr; 1295 u_int gen; 1296 SLIST_ENTRY(exec_args_kva) next; 1297 }; 1298 1299 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1300 1301 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1302 static struct mtx exec_args_kva_mtx; 1303 static u_int exec_args_gen; 1304 1305 static void 1306 exec_prealloc_args_kva(void *arg __unused) 1307 { 1308 struct exec_args_kva *argkva; 1309 u_int i; 1310 1311 SLIST_INIT(&exec_args_kva_freelist); 1312 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1313 for (i = 0; i < exec_map_entries; i++) { 1314 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1315 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1316 argkva->gen = exec_args_gen; 1317 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1318 } 1319 } 1320 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1321 1322 static vm_offset_t 1323 exec_alloc_args_kva(void **cookie) 1324 { 1325 struct exec_args_kva *argkva; 1326 1327 argkva = (void *)atomic_readandclear_ptr( 1328 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1329 if (argkva == NULL) { 1330 mtx_lock(&exec_args_kva_mtx); 1331 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1332 (void)mtx_sleep(&exec_args_kva_freelist, 1333 &exec_args_kva_mtx, 0, "execkva", 0); 1334 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1335 mtx_unlock(&exec_args_kva_mtx); 1336 } 1337 *(struct exec_args_kva **)cookie = argkva; 1338 return (argkva->addr); 1339 } 1340 1341 static void 1342 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1343 { 1344 vm_offset_t base; 1345 1346 base = argkva->addr; 1347 if (argkva->gen != gen) { 1348 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1349 MADV_FREE); 1350 argkva->gen = gen; 1351 } 1352 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1353 (uintptr_t)NULL, (uintptr_t)argkva)) { 1354 mtx_lock(&exec_args_kva_mtx); 1355 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1356 wakeup_one(&exec_args_kva_freelist); 1357 mtx_unlock(&exec_args_kva_mtx); 1358 } 1359 } 1360 1361 static void 1362 exec_free_args_kva(void *cookie) 1363 { 1364 1365 exec_release_args_kva(cookie, exec_args_gen); 1366 } 1367 1368 static void 1369 exec_args_kva_lowmem(void *arg __unused) 1370 { 1371 SLIST_HEAD(, exec_args_kva) head; 1372 struct exec_args_kva *argkva; 1373 u_int gen; 1374 int i; 1375 1376 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1377 1378 /* 1379 * Force an madvise of each KVA range. Any currently allocated ranges 1380 * will have MADV_FREE applied once they are freed. 1381 */ 1382 SLIST_INIT(&head); 1383 mtx_lock(&exec_args_kva_mtx); 1384 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1385 mtx_unlock(&exec_args_kva_mtx); 1386 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1387 SLIST_REMOVE_HEAD(&head, next); 1388 exec_release_args_kva(argkva, gen); 1389 } 1390 1391 CPU_FOREACH(i) { 1392 argkva = (void *)atomic_readandclear_ptr( 1393 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1394 if (argkva != NULL) 1395 exec_release_args_kva(argkva, gen); 1396 } 1397 } 1398 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1399 EVENTHANDLER_PRI_ANY); 1400 1401 /* 1402 * Allocate temporary demand-paged, zero-filled memory for the file name, 1403 * argument, and environment strings. 1404 */ 1405 int 1406 exec_alloc_args(struct image_args *args) 1407 { 1408 1409 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1410 return (0); 1411 } 1412 1413 void 1414 exec_free_args(struct image_args *args) 1415 { 1416 1417 if (args->buf != NULL) { 1418 exec_free_args_kva(args->bufkva); 1419 args->buf = NULL; 1420 } 1421 if (args->fname_buf != NULL) { 1422 free(args->fname_buf, M_TEMP); 1423 args->fname_buf = NULL; 1424 } 1425 if (args->fdp != NULL) 1426 fdescfree_remapped(args->fdp); 1427 } 1428 1429 /* 1430 * A set to functions to fill struct image args. 1431 * 1432 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1433 * fname) before the other functions. All exec_args_add_arg() calls must 1434 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1435 * may be called any time after exec_args_add_fname(). 1436 * 1437 * exec_args_add_fname() - install path to be executed 1438 * exec_args_add_arg() - append an argument string 1439 * exec_args_add_env() - append an env string 1440 * exec_args_adjust_args() - adjust location of the argument list to 1441 * allow new arguments to be prepended 1442 */ 1443 int 1444 exec_args_add_fname(struct image_args *args, const char *fname, 1445 enum uio_seg segflg) 1446 { 1447 int error; 1448 size_t length; 1449 1450 KASSERT(args->fname == NULL, ("fname already appended")); 1451 KASSERT(args->endp == NULL, ("already appending to args")); 1452 1453 if (fname != NULL) { 1454 args->fname = args->buf; 1455 error = segflg == UIO_SYSSPACE ? 1456 copystr(fname, args->fname, PATH_MAX, &length) : 1457 copyinstr(fname, args->fname, PATH_MAX, &length); 1458 if (error != 0) 1459 return (error == ENAMETOOLONG ? E2BIG : error); 1460 } else 1461 length = 0; 1462 1463 /* Set up for _arg_*()/_env_*() */ 1464 args->endp = args->buf + length; 1465 /* begin_argv must be set and kept updated */ 1466 args->begin_argv = args->endp; 1467 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1468 ("too little space remaining for arguments %zu < %zu", 1469 exec_map_entry_size - length, (size_t)ARG_MAX)); 1470 args->stringspace = ARG_MAX; 1471 1472 return (0); 1473 } 1474 1475 static int 1476 exec_args_add_str(struct image_args *args, const char *str, 1477 enum uio_seg segflg, int *countp) 1478 { 1479 int error; 1480 size_t length; 1481 1482 KASSERT(args->endp != NULL, ("endp not initialized")); 1483 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1484 1485 error = (segflg == UIO_SYSSPACE) ? 1486 copystr(str, args->endp, args->stringspace, &length) : 1487 copyinstr(str, args->endp, args->stringspace, &length); 1488 if (error != 0) 1489 return (error == ENAMETOOLONG ? E2BIG : error); 1490 args->stringspace -= length; 1491 args->endp += length; 1492 (*countp)++; 1493 1494 return (0); 1495 } 1496 1497 int 1498 exec_args_add_arg(struct image_args *args, const char *argp, 1499 enum uio_seg segflg) 1500 { 1501 1502 KASSERT(args->envc == 0, ("appending args after env")); 1503 1504 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1505 } 1506 1507 int 1508 exec_args_add_env(struct image_args *args, const char *envp, 1509 enum uio_seg segflg) 1510 { 1511 1512 if (args->envc == 0) 1513 args->begin_envv = args->endp; 1514 1515 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1516 } 1517 1518 int 1519 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1520 { 1521 ssize_t offset; 1522 1523 KASSERT(args->endp != NULL, ("endp not initialized")); 1524 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1525 1526 offset = extend - consume; 1527 if (args->stringspace < offset) 1528 return (E2BIG); 1529 memmove(args->begin_argv + extend, args->begin_argv + consume, 1530 args->endp - args->begin_argv + consume); 1531 if (args->envc > 0) 1532 args->begin_envv += offset; 1533 args->endp += offset; 1534 args->stringspace -= offset; 1535 return (0); 1536 } 1537 1538 char * 1539 exec_args_get_begin_envv(struct image_args *args) 1540 { 1541 1542 KASSERT(args->endp != NULL, ("endp not initialized")); 1543 1544 if (args->envc > 0) 1545 return (args->begin_envv); 1546 return (args->endp); 1547 } 1548 1549 /* 1550 * Copy strings out to the new process address space, constructing new arg 1551 * and env vector tables. Return a pointer to the base so that it can be used 1552 * as the initial stack pointer. 1553 */ 1554 register_t * 1555 exec_copyout_strings(struct image_params *imgp) 1556 { 1557 int argc, envc; 1558 char **vectp; 1559 char *stringp; 1560 uintptr_t destp; 1561 register_t *stack_base; 1562 struct ps_strings *arginfo; 1563 struct proc *p; 1564 size_t execpath_len; 1565 int szsigcode, szps; 1566 char canary[sizeof(long) * 8]; 1567 1568 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1569 /* 1570 * Calculate string base and vector table pointers. 1571 * Also deal with signal trampoline code for this exec type. 1572 */ 1573 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1574 execpath_len = strlen(imgp->execpath) + 1; 1575 else 1576 execpath_len = 0; 1577 p = imgp->proc; 1578 szsigcode = 0; 1579 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1580 if (p->p_sysent->sv_sigcode_base == 0) { 1581 if (p->p_sysent->sv_szsigcode != NULL) 1582 szsigcode = *(p->p_sysent->sv_szsigcode); 1583 } 1584 destp = (uintptr_t)arginfo; 1585 1586 /* 1587 * install sigcode 1588 */ 1589 if (szsigcode != 0) { 1590 destp -= szsigcode; 1591 destp = rounddown2(destp, sizeof(void *)); 1592 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1593 } 1594 1595 /* 1596 * Copy the image path for the rtld. 1597 */ 1598 if (execpath_len != 0) { 1599 destp -= execpath_len; 1600 destp = rounddown2(destp, sizeof(void *)); 1601 imgp->execpathp = destp; 1602 copyout(imgp->execpath, (void *)destp, execpath_len); 1603 } 1604 1605 /* 1606 * Prepare the canary for SSP. 1607 */ 1608 arc4rand(canary, sizeof(canary), 0); 1609 destp -= sizeof(canary); 1610 imgp->canary = destp; 1611 copyout(canary, (void *)destp, sizeof(canary)); 1612 imgp->canarylen = sizeof(canary); 1613 1614 /* 1615 * Prepare the pagesizes array. 1616 */ 1617 destp -= szps; 1618 destp = rounddown2(destp, sizeof(void *)); 1619 imgp->pagesizes = destp; 1620 copyout(pagesizes, (void *)destp, szps); 1621 imgp->pagesizeslen = szps; 1622 1623 destp -= ARG_MAX - imgp->args->stringspace; 1624 destp = rounddown2(destp, sizeof(void *)); 1625 1626 vectp = (char **)destp; 1627 if (imgp->sysent->sv_stackgap != NULL) 1628 imgp->sysent->sv_stackgap(imgp, (u_long *)&vectp); 1629 1630 if (imgp->auxargs) { 1631 /* 1632 * Allocate room on the stack for the ELF auxargs 1633 * array. It has up to AT_COUNT entries. 1634 */ 1635 vectp -= howmany(AT_COUNT * sizeof(Elf_Auxinfo), 1636 sizeof(*vectp)); 1637 } 1638 1639 /* 1640 * Allocate room for the argv[] and env vectors including the 1641 * terminating NULL pointers. 1642 */ 1643 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1644 1645 /* 1646 * vectp also becomes our initial stack base 1647 */ 1648 stack_base = (register_t *)vectp; 1649 1650 stringp = imgp->args->begin_argv; 1651 argc = imgp->args->argc; 1652 envc = imgp->args->envc; 1653 1654 /* 1655 * Copy out strings - arguments and environment. 1656 */ 1657 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1658 1659 /* 1660 * Fill in "ps_strings" struct for ps, w, etc. 1661 */ 1662 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1663 suword32(&arginfo->ps_nargvstr, argc); 1664 1665 /* 1666 * Fill in argument portion of vector table. 1667 */ 1668 for (; argc > 0; --argc) { 1669 suword(vectp++, (long)(intptr_t)destp); 1670 while (*stringp++ != 0) 1671 destp++; 1672 destp++; 1673 } 1674 1675 /* a null vector table pointer separates the argp's from the envp's */ 1676 suword(vectp++, 0); 1677 1678 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1679 suword32(&arginfo->ps_nenvstr, envc); 1680 1681 /* 1682 * Fill in environment portion of vector table. 1683 */ 1684 for (; envc > 0; --envc) { 1685 suword(vectp++, (long)(intptr_t)destp); 1686 while (*stringp++ != 0) 1687 destp++; 1688 destp++; 1689 } 1690 1691 /* end of vector table is a null pointer */ 1692 suword(vectp, 0); 1693 1694 return (stack_base); 1695 } 1696 1697 /* 1698 * Check permissions of file to execute. 1699 * Called with imgp->vp locked. 1700 * Return 0 for success or error code on failure. 1701 */ 1702 int 1703 exec_check_permissions(struct image_params *imgp) 1704 { 1705 struct vnode *vp = imgp->vp; 1706 struct vattr *attr = imgp->attr; 1707 struct thread *td; 1708 int error; 1709 1710 td = curthread; 1711 1712 /* Get file attributes */ 1713 error = VOP_GETATTR(vp, attr, td->td_ucred); 1714 if (error) 1715 return (error); 1716 1717 #ifdef MAC 1718 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1719 if (error) 1720 return (error); 1721 #endif 1722 1723 /* 1724 * 1) Check if file execution is disabled for the filesystem that 1725 * this file resides on. 1726 * 2) Ensure that at least one execute bit is on. Otherwise, a 1727 * privileged user will always succeed, and we don't want this 1728 * to happen unless the file really is executable. 1729 * 3) Ensure that the file is a regular file. 1730 */ 1731 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1732 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1733 (attr->va_type != VREG)) 1734 return (EACCES); 1735 1736 /* 1737 * Zero length files can't be exec'd 1738 */ 1739 if (attr->va_size == 0) 1740 return (ENOEXEC); 1741 1742 /* 1743 * Check for execute permission to file based on current credentials. 1744 */ 1745 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1746 if (error) 1747 return (error); 1748 1749 /* 1750 * Check number of open-for-writes on the file and deny execution 1751 * if there are any. 1752 * 1753 * Add a text reference now so no one can write to the 1754 * executable while we're activating it. 1755 * 1756 * Remember if this was set before and unset it in case this is not 1757 * actually an executable image. 1758 */ 1759 error = VOP_SET_TEXT(vp); 1760 if (error != 0) 1761 return (error); 1762 imgp->textset = true; 1763 1764 /* 1765 * Call filesystem specific open routine (which does nothing in the 1766 * general case). 1767 */ 1768 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1769 if (error == 0) 1770 imgp->opened = 1; 1771 return (error); 1772 } 1773 1774 /* 1775 * Exec handler registration 1776 */ 1777 int 1778 exec_register(const struct execsw *execsw_arg) 1779 { 1780 const struct execsw **es, **xs, **newexecsw; 1781 u_int count = 2; /* New slot and trailing NULL */ 1782 1783 if (execsw) 1784 for (es = execsw; *es; es++) 1785 count++; 1786 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1787 xs = newexecsw; 1788 if (execsw) 1789 for (es = execsw; *es; es++) 1790 *xs++ = *es; 1791 *xs++ = execsw_arg; 1792 *xs = NULL; 1793 if (execsw) 1794 free(execsw, M_TEMP); 1795 execsw = newexecsw; 1796 return (0); 1797 } 1798 1799 int 1800 exec_unregister(const struct execsw *execsw_arg) 1801 { 1802 const struct execsw **es, **xs, **newexecsw; 1803 int count = 1; 1804 1805 if (execsw == NULL) 1806 panic("unregister with no handlers left?\n"); 1807 1808 for (es = execsw; *es; es++) { 1809 if (*es == execsw_arg) 1810 break; 1811 } 1812 if (*es == NULL) 1813 return (ENOENT); 1814 for (es = execsw; *es; es++) 1815 if (*es != execsw_arg) 1816 count++; 1817 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1818 xs = newexecsw; 1819 for (es = execsw; *es; es++) 1820 if (*es != execsw_arg) 1821 *xs++ = *es; 1822 *xs = NULL; 1823 if (execsw) 1824 free(execsw, M_TEMP); 1825 execsw = newexecsw; 1826 return (0); 1827 } 1828