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