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/priv.h> 55 #include <sys/proc.h> 56 #include <sys/ptrace.h> 57 #include <sys/resourcevar.h> 58 #include <sys/rwlock.h> 59 #include <sys/sched.h> 60 #include <sys/sdt.h> 61 #include <sys/sf_buf.h> 62 #include <sys/shm.h> 63 #include <sys/signalvar.h> 64 #include <sys/smp.h> 65 #include <sys/stat.h> 66 #include <sys/syscallsubr.h> 67 #include <sys/sysctl.h> 68 #include <sys/sysent.h> 69 #include <sys/sysproto.h> 70 #include <sys/vnode.h> 71 #include <sys/wait.h> 72 #ifdef KTRACE 73 #include <sys/ktrace.h> 74 #endif 75 76 #include <vm/vm.h> 77 #include <vm/vm_param.h> 78 #include <vm/pmap.h> 79 #include <vm/vm_page.h> 80 #include <vm/vm_map.h> 81 #include <vm/vm_kern.h> 82 #include <vm/vm_extern.h> 83 #include <vm/vm_object.h> 84 #include <vm/vm_pager.h> 85 86 #ifdef HWPMC_HOOKS 87 #include <sys/pmckern.h> 88 #endif 89 90 #include <machine/reg.h> 91 92 #include <security/audit/audit.h> 93 #include <security/mac/mac_framework.h> 94 95 #ifdef KDTRACE_HOOKS 96 #include <sys/dtrace_bsd.h> 97 dtrace_execexit_func_t dtrace_fasttrap_exec; 98 #endif 99 100 SDT_PROVIDER_DECLARE(proc); 101 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 102 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 103 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 104 105 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 106 107 int coredump_pack_fileinfo = 1; 108 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 109 &coredump_pack_fileinfo, 0, 110 "Enable file path packing in 'procstat -f' coredump notes"); 111 112 int coredump_pack_vmmapinfo = 1; 113 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 114 &coredump_pack_vmmapinfo, 0, 115 "Enable file path packing in 'procstat -v' coredump notes"); 116 117 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 118 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 119 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 120 static int do_execve(struct thread *td, struct image_args *args, 121 struct mac *mac_p); 122 123 /* XXX This should be vm_size_t. */ 124 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 125 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", 126 "Location of process' ps_strings structure"); 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 "Top of process stack"); 132 133 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 134 NULL, 0, sysctl_kern_stackprot, "I", 135 "Stack memory permissions"); 136 137 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 138 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 139 &ps_arg_cache_limit, 0, 140 "Process' command line characters cache limit"); 141 142 static int disallow_high_osrel; 143 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 144 &disallow_high_osrel, 0, 145 "Disallow execution of binaries built for higher version of the world"); 146 147 static int map_at_zero = 0; 148 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 149 "Permit processes to map an object at virtual address 0."); 150 151 static int 152 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 153 { 154 struct proc *p; 155 int error; 156 157 p = curproc; 158 #ifdef SCTL_MASK32 159 if (req->flags & SCTL_MASK32) { 160 unsigned int val; 161 val = (unsigned int)p->p_sysent->sv_psstrings; 162 error = SYSCTL_OUT(req, &val, sizeof(val)); 163 } else 164 #endif 165 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 166 sizeof(p->p_sysent->sv_psstrings)); 167 return error; 168 } 169 170 static int 171 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 172 { 173 struct proc *p; 174 int error; 175 176 p = curproc; 177 #ifdef SCTL_MASK32 178 if (req->flags & SCTL_MASK32) { 179 unsigned int val; 180 val = (unsigned int)p->p_sysent->sv_usrstack; 181 error = SYSCTL_OUT(req, &val, sizeof(val)); 182 } else 183 #endif 184 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 185 sizeof(p->p_sysent->sv_usrstack)); 186 return error; 187 } 188 189 static int 190 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 191 { 192 struct proc *p; 193 194 p = curproc; 195 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 196 sizeof(p->p_sysent->sv_stackprot))); 197 } 198 199 /* 200 * Each of the items is a pointer to a `const struct execsw', hence the 201 * double pointer here. 202 */ 203 static const struct execsw **execsw; 204 205 #ifndef _SYS_SYSPROTO_H_ 206 struct execve_args { 207 char *fname; 208 char **argv; 209 char **envv; 210 }; 211 #endif 212 213 int 214 sys_execve(struct thread *td, struct execve_args *uap) 215 { 216 struct image_args args; 217 struct vmspace *oldvmspace; 218 int error; 219 220 error = pre_execve(td, &oldvmspace); 221 if (error != 0) 222 return (error); 223 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 224 uap->argv, uap->envv); 225 if (error == 0) 226 error = kern_execve(td, &args, NULL); 227 post_execve(td, error, oldvmspace); 228 return (error); 229 } 230 231 #ifndef _SYS_SYSPROTO_H_ 232 struct fexecve_args { 233 int fd; 234 char **argv; 235 char **envv; 236 }; 237 #endif 238 int 239 sys_fexecve(struct thread *td, struct fexecve_args *uap) 240 { 241 struct image_args args; 242 struct vmspace *oldvmspace; 243 int error; 244 245 error = pre_execve(td, &oldvmspace); 246 if (error != 0) 247 return (error); 248 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 249 uap->argv, uap->envv); 250 if (error == 0) { 251 args.fd = uap->fd; 252 error = kern_execve(td, &args, NULL); 253 } 254 post_execve(td, error, oldvmspace); 255 return (error); 256 } 257 258 #ifndef _SYS_SYSPROTO_H_ 259 struct __mac_execve_args { 260 char *fname; 261 char **argv; 262 char **envv; 263 struct mac *mac_p; 264 }; 265 #endif 266 267 int 268 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 269 { 270 #ifdef MAC 271 struct image_args args; 272 struct vmspace *oldvmspace; 273 int error; 274 275 error = pre_execve(td, &oldvmspace); 276 if (error != 0) 277 return (error); 278 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 279 uap->argv, uap->envv); 280 if (error == 0) 281 error = kern_execve(td, &args, uap->mac_p); 282 post_execve(td, error, oldvmspace); 283 return (error); 284 #else 285 return (ENOSYS); 286 #endif 287 } 288 289 int 290 pre_execve(struct thread *td, struct vmspace **oldvmspace) 291 { 292 struct proc *p; 293 int error; 294 295 KASSERT(td == curthread, ("non-current thread %p", td)); 296 error = 0; 297 p = td->td_proc; 298 if ((p->p_flag & P_HADTHREADS) != 0) { 299 PROC_LOCK(p); 300 if (thread_single(p, SINGLE_BOUNDARY) != 0) 301 error = ERESTART; 302 PROC_UNLOCK(p); 303 } 304 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 305 ("nested execve")); 306 *oldvmspace = p->p_vmspace; 307 return (error); 308 } 309 310 void 311 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 312 { 313 struct proc *p; 314 315 KASSERT(td == curthread, ("non-current thread %p", td)); 316 p = td->td_proc; 317 if ((p->p_flag & P_HADTHREADS) != 0) { 318 PROC_LOCK(p); 319 /* 320 * If success, we upgrade to SINGLE_EXIT state to 321 * force other threads to suicide. 322 */ 323 if (error == EJUSTRETURN) 324 thread_single(p, SINGLE_EXIT); 325 else 326 thread_single_end(p, SINGLE_BOUNDARY); 327 PROC_UNLOCK(p); 328 } 329 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 330 KASSERT(p->p_vmspace != oldvmspace, 331 ("oldvmspace still used")); 332 vmspace_free(oldvmspace); 333 td->td_pflags &= ~TDP_EXECVMSPC; 334 } 335 } 336 337 /* 338 * XXX: kern_execve has the astonishing property of not always returning to 339 * the caller. If sufficiently bad things happen during the call to 340 * do_execve(), it can end up calling exit1(); as a result, callers must 341 * avoid doing anything which they might need to undo (e.g., allocating 342 * memory). 343 */ 344 int 345 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 346 { 347 348 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 349 exec_args_get_begin_envv(args) - args->begin_argv); 350 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc, 351 args->endp - exec_args_get_begin_envv(args)); 352 return (do_execve(td, args, mac_p)); 353 } 354 355 /* 356 * In-kernel implementation of execve(). All arguments are assumed to be 357 * userspace pointers from the passed thread. 358 */ 359 static int 360 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p) 361 { 362 struct proc *p = td->td_proc; 363 struct nameidata nd; 364 struct ucred *oldcred; 365 struct uidinfo *euip = NULL; 366 uintptr_t stack_base; 367 struct image_params image_params, *imgp; 368 struct vattr attr; 369 int (*img_first)(struct image_params *); 370 struct pargs *oldargs = NULL, *newargs = NULL; 371 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 372 #ifdef KTRACE 373 struct vnode *tracevp = NULL; 374 struct ucred *tracecred = NULL; 375 #endif 376 struct vnode *oldtextvp = NULL, *newtextvp; 377 int credential_changing; 378 #ifdef MAC 379 struct label *interpvplabel = NULL; 380 int will_transition; 381 #endif 382 #ifdef HWPMC_HOOKS 383 struct pmckern_procexec pe; 384 #endif 385 int error, i, orig_osrel; 386 uint32_t orig_fctl0; 387 static const char fexecv_proc_title[] = "(fexecv)"; 388 389 imgp = &image_params; 390 391 /* 392 * Lock the process and set the P_INEXEC flag to indicate that 393 * it should be left alone until we're done here. This is 394 * necessary to avoid race conditions - e.g. in ptrace() - 395 * that might allow a local user to illicitly obtain elevated 396 * privileges. 397 */ 398 PROC_LOCK(p); 399 KASSERT((p->p_flag & P_INEXEC) == 0, 400 ("%s(): process already has P_INEXEC flag", __func__)); 401 p->p_flag |= P_INEXEC; 402 PROC_UNLOCK(p); 403 404 /* 405 * Initialize part of the common data 406 */ 407 bzero(imgp, sizeof(*imgp)); 408 imgp->proc = p; 409 imgp->attr = &attr; 410 imgp->args = args; 411 oldcred = p->p_ucred; 412 orig_osrel = p->p_osrel; 413 orig_fctl0 = p->p_fctl0; 414 415 #ifdef MAC 416 error = mac_execve_enter(imgp, mac_p); 417 if (error) 418 goto exec_fail; 419 #endif 420 421 /* 422 * Translate the file name. namei() returns a vnode pointer 423 * in ni_vp among other things. 424 * 425 * XXXAUDIT: It would be desirable to also audit the name of the 426 * interpreter if this is an interpreted binary. 427 */ 428 if (args->fname != NULL) { 429 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 430 SAVENAME | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 431 } 432 433 SDT_PROBE1(proc, , , exec, args->fname); 434 435 interpret: 436 if (args->fname != NULL) { 437 #ifdef CAPABILITY_MODE 438 /* 439 * While capability mode can't reach this point via direct 440 * path arguments to execve(), we also don't allow 441 * interpreters to be used in capability mode (for now). 442 * Catch indirect lookups and return a permissions error. 443 */ 444 if (IN_CAPABILITY_MODE(td)) { 445 error = ECAPMODE; 446 goto exec_fail; 447 } 448 #endif 449 error = namei(&nd); 450 if (error) 451 goto exec_fail; 452 453 newtextvp = nd.ni_vp; 454 imgp->vp = newtextvp; 455 } else { 456 AUDIT_ARG_FD(args->fd); 457 /* 458 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 459 */ 460 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp); 461 if (error) 462 goto exec_fail; 463 vn_lock(newtextvp, LK_SHARED | LK_RETRY); 464 AUDIT_ARG_VNODE1(newtextvp); 465 imgp->vp = newtextvp; 466 } 467 468 /* 469 * Check file permissions. Also 'opens' file and sets its vnode to 470 * text mode. 471 */ 472 error = exec_check_permissions(imgp); 473 if (error) 474 goto exec_fail_dealloc; 475 476 imgp->object = imgp->vp->v_object; 477 if (imgp->object != NULL) 478 vm_object_reference(imgp->object); 479 480 error = exec_map_first_page(imgp); 481 if (error) 482 goto exec_fail_dealloc; 483 484 imgp->proc->p_osrel = 0; 485 imgp->proc->p_fctl0 = 0; 486 487 /* 488 * Implement image setuid/setgid. 489 * 490 * Determine new credentials before attempting image activators 491 * so that it can be used by process_exec handlers to determine 492 * credential/setid changes. 493 * 494 * Don't honor setuid/setgid if the filesystem prohibits it or if 495 * the process is being traced. 496 * 497 * We disable setuid/setgid/etc in capability mode on the basis 498 * that most setugid applications are not written with that 499 * environment in mind, and will therefore almost certainly operate 500 * incorrectly. In principle there's no reason that setugid 501 * applications might not be useful in capability mode, so we may want 502 * to reconsider this conservative design choice in the future. 503 * 504 * XXXMAC: For the time being, use NOSUID to also prohibit 505 * transitions on the file system. 506 */ 507 credential_changing = 0; 508 credential_changing |= (attr.va_mode & S_ISUID) && 509 oldcred->cr_uid != attr.va_uid; 510 credential_changing |= (attr.va_mode & S_ISGID) && 511 oldcred->cr_gid != attr.va_gid; 512 #ifdef MAC 513 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 514 interpvplabel, imgp); 515 credential_changing |= will_transition; 516 #endif 517 518 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 519 if (credential_changing) 520 imgp->proc->p_pdeathsig = 0; 521 522 if (credential_changing && 523 #ifdef CAPABILITY_MODE 524 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 525 #endif 526 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 527 (p->p_flag & P_TRACED) == 0) { 528 imgp->credential_setid = true; 529 VOP_UNLOCK(imgp->vp); 530 imgp->newcred = crdup(oldcred); 531 if (attr.va_mode & S_ISUID) { 532 euip = uifind(attr.va_uid); 533 change_euid(imgp->newcred, euip); 534 } 535 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 536 if (attr.va_mode & S_ISGID) 537 change_egid(imgp->newcred, attr.va_gid); 538 /* 539 * Implement correct POSIX saved-id behavior. 540 * 541 * XXXMAC: Note that the current logic will save the 542 * uid and gid if a MAC domain transition occurs, even 543 * though maybe it shouldn't. 544 */ 545 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 546 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 547 } else { 548 /* 549 * Implement correct POSIX saved-id behavior. 550 * 551 * XXX: It's not clear that the existing behavior is 552 * POSIX-compliant. A number of sources indicate that the 553 * saved uid/gid should only be updated if the new ruid is 554 * not equal to the old ruid, or the new euid is not equal 555 * to the old euid and the new euid is not equal to the old 556 * ruid. The FreeBSD code always updates the saved uid/gid. 557 * Also, this code uses the new (replaced) euid and egid as 558 * the source, which may or may not be the right ones to use. 559 */ 560 if (oldcred->cr_svuid != oldcred->cr_uid || 561 oldcred->cr_svgid != oldcred->cr_gid) { 562 VOP_UNLOCK(imgp->vp); 563 imgp->newcred = crdup(oldcred); 564 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 565 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 566 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 567 } 568 } 569 /* The new credentials are installed into the process later. */ 570 571 /* 572 * Do the best to calculate the full path to the image file. 573 */ 574 if (args->fname != NULL && args->fname[0] == '/') 575 imgp->execpath = args->fname; 576 else { 577 VOP_UNLOCK(imgp->vp); 578 if (vn_fullpath(td, imgp->vp, &imgp->execpath, 579 &imgp->freepath) != 0) 580 imgp->execpath = args->fname; 581 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 582 } 583 584 /* 585 * If the current process has a special image activator it 586 * wants to try first, call it. For example, emulating shell 587 * scripts differently. 588 */ 589 error = -1; 590 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 591 error = img_first(imgp); 592 593 /* 594 * Loop through the list of image activators, calling each one. 595 * An activator returns -1 if there is no match, 0 on success, 596 * and an error otherwise. 597 */ 598 for (i = 0; error == -1 && execsw[i]; ++i) { 599 if (execsw[i]->ex_imgact == NULL || 600 execsw[i]->ex_imgact == img_first) { 601 continue; 602 } 603 error = (*execsw[i]->ex_imgact)(imgp); 604 } 605 606 if (error) { 607 if (error == -1) 608 error = ENOEXEC; 609 goto exec_fail_dealloc; 610 } 611 612 /* 613 * Special interpreter operation, cleanup and loop up to try to 614 * activate the interpreter. 615 */ 616 if (imgp->interpreted) { 617 exec_unmap_first_page(imgp); 618 /* 619 * The text reference needs to be removed for scripts. 620 * There is a short period before we determine that 621 * something is a script where text reference is active. 622 * The vnode lock is held over this entire period 623 * so nothing should illegitimately be blocked. 624 */ 625 MPASS(imgp->textset); 626 VOP_UNSET_TEXT_CHECKED(newtextvp); 627 imgp->textset = false; 628 /* free name buffer and old vnode */ 629 if (args->fname != NULL) 630 NDFREE(&nd, NDF_ONLY_PNBUF); 631 #ifdef MAC 632 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 633 #endif 634 if (imgp->opened) { 635 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 636 imgp->opened = 0; 637 } 638 vput(newtextvp); 639 vm_object_deallocate(imgp->object); 640 imgp->object = NULL; 641 imgp->credential_setid = false; 642 if (imgp->newcred != NULL) { 643 crfree(imgp->newcred); 644 imgp->newcred = NULL; 645 } 646 imgp->execpath = NULL; 647 free(imgp->freepath, M_TEMP); 648 imgp->freepath = NULL; 649 /* set new name to that of the interpreter */ 650 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 651 SAVENAME, UIO_SYSSPACE, imgp->interpreter_name, td); 652 args->fname = imgp->interpreter_name; 653 goto interpret; 654 } 655 656 /* 657 * NB: We unlock the vnode here because it is believed that none 658 * of the sv_copyout_strings/sv_fixup operations require the vnode. 659 */ 660 VOP_UNLOCK(imgp->vp); 661 662 if (disallow_high_osrel && 663 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 664 error = ENOEXEC; 665 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 666 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 667 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 668 goto exec_fail_dealloc; 669 } 670 671 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 672 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 673 sys_cap_enter(td, NULL); 674 675 /* 676 * Copy out strings (args and env) and initialize stack base. 677 */ 678 error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base); 679 if (error != 0) { 680 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 681 goto exec_fail_dealloc; 682 } 683 684 /* 685 * Stack setup. 686 */ 687 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 688 if (error != 0) { 689 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 690 goto exec_fail_dealloc; 691 } 692 693 if (args->fdp != NULL) { 694 /* Install a brand new file descriptor table. */ 695 fdinstall_remapped(td, args->fdp); 696 args->fdp = NULL; 697 } else { 698 /* 699 * Keep on using the existing file descriptor table. For 700 * security and other reasons, the file descriptor table 701 * cannot be shared after an exec. 702 */ 703 fdunshare(td); 704 /* close files on exec */ 705 fdcloseexec(td); 706 } 707 708 /* 709 * Malloc things before we need locks. 710 */ 711 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 712 /* Cache arguments if they fit inside our allowance */ 713 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 714 newargs = pargs_alloc(i); 715 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 716 } 717 718 /* 719 * For security and other reasons, signal handlers cannot 720 * be shared after an exec. The new process gets a copy of the old 721 * handlers. In execsigs(), the new process will have its signals 722 * reset. 723 */ 724 if (sigacts_shared(p->p_sigacts)) { 725 oldsigacts = p->p_sigacts; 726 newsigacts = sigacts_alloc(); 727 sigacts_copy(newsigacts, oldsigacts); 728 } 729 730 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 731 732 PROC_LOCK(p); 733 if (oldsigacts) 734 p->p_sigacts = newsigacts; 735 /* Stop profiling */ 736 stopprofclock(p); 737 738 /* reset caught signals */ 739 execsigs(p); 740 741 /* name this process - nameiexec(p, ndp) */ 742 bzero(p->p_comm, sizeof(p->p_comm)); 743 if (args->fname) 744 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 745 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 746 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 747 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 748 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 749 #ifdef KTR 750 sched_clear_tdname(td); 751 #endif 752 753 /* 754 * mark as execed, wakeup the process that vforked (if any) and tell 755 * it that it now has its own resources back 756 */ 757 p->p_flag |= P_EXEC; 758 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 759 p->p_flag2 &= ~P2_NOTRACE; 760 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 761 p->p_flag2 &= ~P2_STKGAP_DISABLE; 762 if (p->p_flag & P_PPWAIT) { 763 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 764 cv_broadcast(&p->p_pwait); 765 /* STOPs are no longer ignored, arrange for AST */ 766 signotify(td); 767 } 768 769 /* 770 * Implement image setuid/setgid installation. 771 */ 772 if (imgp->credential_setid) { 773 /* 774 * Turn off syscall tracing for set-id programs, except for 775 * root. Record any set-id flags first to make sure that 776 * we do not regain any tracing during a possible block. 777 */ 778 setsugid(p); 779 780 #ifdef KTRACE 781 if (p->p_tracecred != NULL && 782 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED)) 783 ktrprocexec(p, &tracecred, &tracevp); 784 #endif 785 /* 786 * Close any file descriptors 0..2 that reference procfs, 787 * then make sure file descriptors 0..2 are in use. 788 * 789 * Both fdsetugidsafety() and fdcheckstd() may call functions 790 * taking sleepable locks, so temporarily drop our locks. 791 */ 792 PROC_UNLOCK(p); 793 VOP_UNLOCK(imgp->vp); 794 fdsetugidsafety(td); 795 error = fdcheckstd(td); 796 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 797 if (error != 0) 798 goto exec_fail_dealloc; 799 PROC_LOCK(p); 800 #ifdef MAC 801 if (will_transition) { 802 mac_vnode_execve_transition(oldcred, imgp->newcred, 803 imgp->vp, interpvplabel, imgp); 804 } 805 #endif 806 } else { 807 if (oldcred->cr_uid == oldcred->cr_ruid && 808 oldcred->cr_gid == oldcred->cr_rgid) 809 p->p_flag &= ~P_SUGID; 810 } 811 /* 812 * Set the new credentials. 813 */ 814 if (imgp->newcred != NULL) { 815 proc_set_cred(p, imgp->newcred); 816 crfree(oldcred); 817 oldcred = NULL; 818 } 819 820 /* 821 * Store the vp for use in procfs. This vnode was referenced by namei 822 * or fgetvp_exec. 823 */ 824 oldtextvp = p->p_textvp; 825 p->p_textvp = newtextvp; 826 827 #ifdef KDTRACE_HOOKS 828 /* 829 * Tell the DTrace fasttrap provider about the exec if it 830 * has declared an interest. 831 */ 832 if (dtrace_fasttrap_exec) 833 dtrace_fasttrap_exec(p); 834 #endif 835 836 /* 837 * Notify others that we exec'd, and clear the P_INEXEC flag 838 * as we're now a bona fide freshly-execed process. 839 */ 840 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 841 p->p_flag &= ~P_INEXEC; 842 843 /* clear "fork but no exec" flag, as we _are_ execing */ 844 p->p_acflag &= ~AFORK; 845 846 /* 847 * Free any previous argument cache and replace it with 848 * the new argument cache, if any. 849 */ 850 oldargs = p->p_args; 851 p->p_args = newargs; 852 newargs = NULL; 853 854 PROC_UNLOCK(p); 855 856 #ifdef HWPMC_HOOKS 857 /* 858 * Check if system-wide sampling is in effect or if the 859 * current process is using PMCs. If so, do exec() time 860 * processing. This processing needs to happen AFTER the 861 * P_INEXEC flag is cleared. 862 */ 863 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 864 VOP_UNLOCK(imgp->vp); 865 pe.pm_credentialschanged = credential_changing; 866 pe.pm_entryaddr = imgp->entry_addr; 867 868 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 869 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 870 } 871 #endif 872 873 /* Set values passed into the program in registers. */ 874 (*p->p_sysent->sv_setregs)(td, imgp, stack_base); 875 876 VOP_MMAPPED(imgp->vp); 877 878 SDT_PROBE1(proc, , , exec__success, args->fname); 879 880 exec_fail_dealloc: 881 if (error != 0) { 882 p->p_osrel = orig_osrel; 883 p->p_fctl0 = orig_fctl0; 884 } 885 886 if (imgp->firstpage != NULL) 887 exec_unmap_first_page(imgp); 888 889 if (imgp->vp != NULL) { 890 if (args->fname) 891 NDFREE(&nd, NDF_ONLY_PNBUF); 892 if (imgp->opened) 893 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 894 if (imgp->textset) 895 VOP_UNSET_TEXT_CHECKED(imgp->vp); 896 if (error != 0) 897 vput(imgp->vp); 898 else 899 VOP_UNLOCK(imgp->vp); 900 } 901 902 if (imgp->object != NULL) 903 vm_object_deallocate(imgp->object); 904 905 free(imgp->freepath, M_TEMP); 906 907 if (error == 0) { 908 if (p->p_ptevents & PTRACE_EXEC) { 909 PROC_LOCK(p); 910 if (p->p_ptevents & PTRACE_EXEC) 911 td->td_dbgflags |= TDB_EXEC; 912 PROC_UNLOCK(p); 913 } 914 } else { 915 exec_fail: 916 /* we're done here, clear P_INEXEC */ 917 PROC_LOCK(p); 918 p->p_flag &= ~P_INEXEC; 919 PROC_UNLOCK(p); 920 921 SDT_PROBE1(proc, , , exec__failure, error); 922 } 923 924 if (imgp->newcred != NULL && oldcred != NULL) 925 crfree(imgp->newcred); 926 927 #ifdef MAC 928 mac_execve_exit(imgp); 929 mac_execve_interpreter_exit(interpvplabel); 930 #endif 931 exec_free_args(args); 932 933 /* 934 * Handle deferred decrement of ref counts. 935 */ 936 if (oldtextvp != NULL) 937 vrele(oldtextvp); 938 #ifdef KTRACE 939 if (tracevp != NULL) 940 vrele(tracevp); 941 if (tracecred != NULL) 942 crfree(tracecred); 943 #endif 944 pargs_drop(oldargs); 945 pargs_drop(newargs); 946 if (oldsigacts != NULL) 947 sigacts_free(oldsigacts); 948 if (euip != NULL) 949 uifree(euip); 950 951 if (error && imgp->vmspace_destroyed) { 952 /* sorry, no more process anymore. exit gracefully */ 953 exit1(td, 0, SIGABRT); 954 /* NOT REACHED */ 955 } 956 957 #ifdef KTRACE 958 if (error == 0) 959 ktrprocctor(p); 960 #endif 961 962 /* 963 * We don't want cpu_set_syscall_retval() to overwrite any of 964 * the register values put in place by exec_setregs(). 965 * Implementations of cpu_set_syscall_retval() will leave 966 * registers unmodified when returning EJUSTRETURN. 967 */ 968 return (error == 0 ? EJUSTRETURN : error); 969 } 970 971 int 972 exec_map_first_page(struct image_params *imgp) 973 { 974 vm_object_t object; 975 vm_page_t m; 976 int error; 977 978 if (imgp->firstpage != NULL) 979 exec_unmap_first_page(imgp); 980 981 object = imgp->vp->v_object; 982 if (object == NULL) 983 return (EACCES); 984 #if VM_NRESERVLEVEL > 0 985 if ((object->flags & OBJ_COLORED) == 0) { 986 VM_OBJECT_WLOCK(object); 987 vm_object_color(object, 0); 988 VM_OBJECT_WUNLOCK(object); 989 } 990 #endif 991 error = vm_page_grab_valid_unlocked(&m, object, 0, 992 VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) | 993 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED); 994 995 if (error != VM_PAGER_OK) 996 return (EIO); 997 imgp->firstpage = sf_buf_alloc(m, 0); 998 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 999 1000 return (0); 1001 } 1002 1003 void 1004 exec_unmap_first_page(struct image_params *imgp) 1005 { 1006 vm_page_t m; 1007 1008 if (imgp->firstpage != NULL) { 1009 m = sf_buf_page(imgp->firstpage); 1010 sf_buf_free(imgp->firstpage); 1011 imgp->firstpage = NULL; 1012 vm_page_unwire(m, PQ_ACTIVE); 1013 } 1014 } 1015 1016 /* 1017 * Destroy old address space, and allocate a new stack. 1018 * The new stack is only sgrowsiz large because it is grown 1019 * automatically on a page fault. 1020 */ 1021 int 1022 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1023 { 1024 int error; 1025 struct proc *p = imgp->proc; 1026 struct vmspace *vmspace = p->p_vmspace; 1027 struct thread *td = curthread; 1028 vm_object_t obj; 1029 struct rlimit rlim_stack; 1030 vm_offset_t sv_minuser, stack_addr; 1031 vm_map_t map; 1032 u_long ssiz; 1033 1034 imgp->vmspace_destroyed = 1; 1035 imgp->sysent = sv; 1036 1037 sigfastblock_clear(td); 1038 1039 /* May be called with Giant held */ 1040 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1041 1042 /* 1043 * Blow away entire process VM, if address space not shared, 1044 * otherwise, create a new VM space so that other threads are 1045 * not disrupted 1046 */ 1047 map = &vmspace->vm_map; 1048 if (map_at_zero) 1049 sv_minuser = sv->sv_minuser; 1050 else 1051 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1052 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1053 vm_map_max(map) == sv->sv_maxuser && 1054 cpu_exec_vmspace_reuse(p, map)) { 1055 shmexit(vmspace); 1056 pmap_remove_pages(vmspace_pmap(vmspace)); 1057 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1058 /* 1059 * An exec terminates mlockall(MCL_FUTURE), ASLR state 1060 * must be re-evaluated. 1061 */ 1062 vm_map_lock(map); 1063 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1064 MAP_ASLR_IGNSTART); 1065 vm_map_unlock(map); 1066 } else { 1067 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1068 if (error) 1069 return (error); 1070 vmspace = p->p_vmspace; 1071 map = &vmspace->vm_map; 1072 } 1073 map->flags |= imgp->map_flags; 1074 1075 /* Map a shared page */ 1076 obj = sv->sv_shared_page_obj; 1077 if (obj != NULL) { 1078 vm_object_reference(obj); 1079 error = vm_map_fixed(map, obj, 0, 1080 sv->sv_shared_page_base, sv->sv_shared_page_len, 1081 VM_PROT_READ | VM_PROT_EXECUTE, 1082 VM_PROT_READ | VM_PROT_EXECUTE, 1083 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1084 if (error != KERN_SUCCESS) { 1085 vm_object_deallocate(obj); 1086 return (vm_mmap_to_errno(error)); 1087 } 1088 } 1089 1090 /* Allocate a new stack */ 1091 if (imgp->stack_sz != 0) { 1092 ssiz = trunc_page(imgp->stack_sz); 1093 PROC_LOCK(p); 1094 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1095 PROC_UNLOCK(p); 1096 if (ssiz > rlim_stack.rlim_max) 1097 ssiz = rlim_stack.rlim_max; 1098 if (ssiz > rlim_stack.rlim_cur) { 1099 rlim_stack.rlim_cur = ssiz; 1100 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1101 } 1102 } else if (sv->sv_maxssiz != NULL) { 1103 ssiz = *sv->sv_maxssiz; 1104 } else { 1105 ssiz = maxssiz; 1106 } 1107 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1108 if (ssiz < imgp->eff_stack_sz) 1109 imgp->eff_stack_sz = ssiz; 1110 stack_addr = sv->sv_usrstack - ssiz; 1111 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1112 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1113 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1114 if (error != KERN_SUCCESS) 1115 return (vm_mmap_to_errno(error)); 1116 1117 /* 1118 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1119 * are still used to enforce the stack rlimit on the process stack. 1120 */ 1121 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1122 vmspace->vm_maxsaddr = (char *)stack_addr; 1123 1124 return (0); 1125 } 1126 1127 /* 1128 * Copy out argument and environment strings from the old process address 1129 * space into the temporary string buffer. 1130 */ 1131 int 1132 exec_copyin_args(struct image_args *args, const char *fname, 1133 enum uio_seg segflg, char **argv, char **envv) 1134 { 1135 u_long arg, env; 1136 int error; 1137 1138 bzero(args, sizeof(*args)); 1139 if (argv == NULL) 1140 return (EFAULT); 1141 1142 /* 1143 * Allocate demand-paged memory for the file name, argument, and 1144 * environment strings. 1145 */ 1146 error = exec_alloc_args(args); 1147 if (error != 0) 1148 return (error); 1149 1150 /* 1151 * Copy the file name. 1152 */ 1153 error = exec_args_add_fname(args, fname, segflg); 1154 if (error != 0) 1155 goto err_exit; 1156 1157 /* 1158 * extract arguments first 1159 */ 1160 for (;;) { 1161 error = fueword(argv++, &arg); 1162 if (error == -1) { 1163 error = EFAULT; 1164 goto err_exit; 1165 } 1166 if (arg == 0) 1167 break; 1168 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1169 UIO_USERSPACE); 1170 if (error != 0) 1171 goto err_exit; 1172 } 1173 1174 /* 1175 * extract environment strings 1176 */ 1177 if (envv) { 1178 for (;;) { 1179 error = fueword(envv++, &env); 1180 if (error == -1) { 1181 error = EFAULT; 1182 goto err_exit; 1183 } 1184 if (env == 0) 1185 break; 1186 error = exec_args_add_env(args, 1187 (char *)(uintptr_t)env, UIO_USERSPACE); 1188 if (error != 0) 1189 goto err_exit; 1190 } 1191 } 1192 1193 return (0); 1194 1195 err_exit: 1196 exec_free_args(args); 1197 return (error); 1198 } 1199 1200 int 1201 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1202 const void *data, size_t datalen, const int *fds, size_t fdslen) 1203 { 1204 struct filedesc *ofdp; 1205 const char *p; 1206 int *kfds; 1207 int error; 1208 1209 memset(args, '\0', sizeof(*args)); 1210 ofdp = td->td_proc->p_fd; 1211 if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles) 1212 return (E2BIG); 1213 error = exec_alloc_args(args); 1214 if (error != 0) 1215 return (error); 1216 1217 args->begin_argv = args->buf; 1218 args->stringspace = ARG_MAX; 1219 1220 if (datalen > 0) { 1221 /* 1222 * Argument buffer has been provided. Copy it into the 1223 * kernel as a single string and add a terminating null 1224 * byte. 1225 */ 1226 error = copyin(data, args->begin_argv, datalen); 1227 if (error != 0) 1228 goto err_exit; 1229 args->begin_argv[datalen] = '\0'; 1230 args->endp = args->begin_argv + datalen + 1; 1231 args->stringspace -= datalen + 1; 1232 1233 /* 1234 * Traditional argument counting. Count the number of 1235 * null bytes. 1236 */ 1237 for (p = args->begin_argv; p < args->endp; ++p) 1238 if (*p == '\0') 1239 ++args->argc; 1240 } else { 1241 /* No argument buffer provided. */ 1242 args->endp = args->begin_argv; 1243 } 1244 1245 /* Create new file descriptor table. */ 1246 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1247 error = copyin(fds, kfds, fdslen * sizeof(int)); 1248 if (error != 0) { 1249 free(kfds, M_TEMP); 1250 goto err_exit; 1251 } 1252 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1253 free(kfds, M_TEMP); 1254 if (error != 0) 1255 goto err_exit; 1256 1257 return (0); 1258 err_exit: 1259 exec_free_args(args); 1260 return (error); 1261 } 1262 1263 struct exec_args_kva { 1264 vm_offset_t addr; 1265 u_int gen; 1266 SLIST_ENTRY(exec_args_kva) next; 1267 }; 1268 1269 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1270 1271 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1272 static struct mtx exec_args_kva_mtx; 1273 static u_int exec_args_gen; 1274 1275 static void 1276 exec_prealloc_args_kva(void *arg __unused) 1277 { 1278 struct exec_args_kva *argkva; 1279 u_int i; 1280 1281 SLIST_INIT(&exec_args_kva_freelist); 1282 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1283 for (i = 0; i < exec_map_entries; i++) { 1284 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1285 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1286 argkva->gen = exec_args_gen; 1287 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1288 } 1289 } 1290 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1291 1292 static vm_offset_t 1293 exec_alloc_args_kva(void **cookie) 1294 { 1295 struct exec_args_kva *argkva; 1296 1297 argkva = (void *)atomic_readandclear_ptr( 1298 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1299 if (argkva == NULL) { 1300 mtx_lock(&exec_args_kva_mtx); 1301 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1302 (void)mtx_sleep(&exec_args_kva_freelist, 1303 &exec_args_kva_mtx, 0, "execkva", 0); 1304 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1305 mtx_unlock(&exec_args_kva_mtx); 1306 } 1307 *(struct exec_args_kva **)cookie = argkva; 1308 return (argkva->addr); 1309 } 1310 1311 static void 1312 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1313 { 1314 vm_offset_t base; 1315 1316 base = argkva->addr; 1317 if (argkva->gen != gen) { 1318 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1319 MADV_FREE); 1320 argkva->gen = gen; 1321 } 1322 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1323 (uintptr_t)NULL, (uintptr_t)argkva)) { 1324 mtx_lock(&exec_args_kva_mtx); 1325 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1326 wakeup_one(&exec_args_kva_freelist); 1327 mtx_unlock(&exec_args_kva_mtx); 1328 } 1329 } 1330 1331 static void 1332 exec_free_args_kva(void *cookie) 1333 { 1334 1335 exec_release_args_kva(cookie, exec_args_gen); 1336 } 1337 1338 static void 1339 exec_args_kva_lowmem(void *arg __unused) 1340 { 1341 SLIST_HEAD(, exec_args_kva) head; 1342 struct exec_args_kva *argkva; 1343 u_int gen; 1344 int i; 1345 1346 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1347 1348 /* 1349 * Force an madvise of each KVA range. Any currently allocated ranges 1350 * will have MADV_FREE applied once they are freed. 1351 */ 1352 SLIST_INIT(&head); 1353 mtx_lock(&exec_args_kva_mtx); 1354 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1355 mtx_unlock(&exec_args_kva_mtx); 1356 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1357 SLIST_REMOVE_HEAD(&head, next); 1358 exec_release_args_kva(argkva, gen); 1359 } 1360 1361 CPU_FOREACH(i) { 1362 argkva = (void *)atomic_readandclear_ptr( 1363 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1364 if (argkva != NULL) 1365 exec_release_args_kva(argkva, gen); 1366 } 1367 } 1368 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1369 EVENTHANDLER_PRI_ANY); 1370 1371 /* 1372 * Allocate temporary demand-paged, zero-filled memory for the file name, 1373 * argument, and environment strings. 1374 */ 1375 int 1376 exec_alloc_args(struct image_args *args) 1377 { 1378 1379 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1380 return (0); 1381 } 1382 1383 void 1384 exec_free_args(struct image_args *args) 1385 { 1386 1387 if (args->buf != NULL) { 1388 exec_free_args_kva(args->bufkva); 1389 args->buf = NULL; 1390 } 1391 if (args->fname_buf != NULL) { 1392 free(args->fname_buf, M_TEMP); 1393 args->fname_buf = NULL; 1394 } 1395 if (args->fdp != NULL) 1396 fdescfree_remapped(args->fdp); 1397 } 1398 1399 /* 1400 * A set to functions to fill struct image args. 1401 * 1402 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1403 * fname) before the other functions. All exec_args_add_arg() calls must 1404 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1405 * may be called any time after exec_args_add_fname(). 1406 * 1407 * exec_args_add_fname() - install path to be executed 1408 * exec_args_add_arg() - append an argument string 1409 * exec_args_add_env() - append an env string 1410 * exec_args_adjust_args() - adjust location of the argument list to 1411 * allow new arguments to be prepended 1412 */ 1413 int 1414 exec_args_add_fname(struct image_args *args, const char *fname, 1415 enum uio_seg segflg) 1416 { 1417 int error; 1418 size_t length; 1419 1420 KASSERT(args->fname == NULL, ("fname already appended")); 1421 KASSERT(args->endp == NULL, ("already appending to args")); 1422 1423 if (fname != NULL) { 1424 args->fname = args->buf; 1425 error = segflg == UIO_SYSSPACE ? 1426 copystr(fname, args->fname, PATH_MAX, &length) : 1427 copyinstr(fname, args->fname, PATH_MAX, &length); 1428 if (error != 0) 1429 return (error == ENAMETOOLONG ? E2BIG : error); 1430 } else 1431 length = 0; 1432 1433 /* Set up for _arg_*()/_env_*() */ 1434 args->endp = args->buf + length; 1435 /* begin_argv must be set and kept updated */ 1436 args->begin_argv = args->endp; 1437 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1438 ("too little space remaining for arguments %zu < %zu", 1439 exec_map_entry_size - length, (size_t)ARG_MAX)); 1440 args->stringspace = ARG_MAX; 1441 1442 return (0); 1443 } 1444 1445 static int 1446 exec_args_add_str(struct image_args *args, const char *str, 1447 enum uio_seg segflg, int *countp) 1448 { 1449 int error; 1450 size_t length; 1451 1452 KASSERT(args->endp != NULL, ("endp not initialized")); 1453 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1454 1455 error = (segflg == UIO_SYSSPACE) ? 1456 copystr(str, args->endp, args->stringspace, &length) : 1457 copyinstr(str, args->endp, args->stringspace, &length); 1458 if (error != 0) 1459 return (error == ENAMETOOLONG ? E2BIG : error); 1460 args->stringspace -= length; 1461 args->endp += length; 1462 (*countp)++; 1463 1464 return (0); 1465 } 1466 1467 int 1468 exec_args_add_arg(struct image_args *args, const char *argp, 1469 enum uio_seg segflg) 1470 { 1471 1472 KASSERT(args->envc == 0, ("appending args after env")); 1473 1474 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1475 } 1476 1477 int 1478 exec_args_add_env(struct image_args *args, const char *envp, 1479 enum uio_seg segflg) 1480 { 1481 1482 if (args->envc == 0) 1483 args->begin_envv = args->endp; 1484 1485 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1486 } 1487 1488 int 1489 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1490 { 1491 ssize_t offset; 1492 1493 KASSERT(args->endp != NULL, ("endp not initialized")); 1494 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1495 1496 offset = extend - consume; 1497 if (args->stringspace < offset) 1498 return (E2BIG); 1499 memmove(args->begin_argv + extend, args->begin_argv + consume, 1500 args->endp - args->begin_argv + consume); 1501 if (args->envc > 0) 1502 args->begin_envv += offset; 1503 args->endp += offset; 1504 args->stringspace -= offset; 1505 return (0); 1506 } 1507 1508 char * 1509 exec_args_get_begin_envv(struct image_args *args) 1510 { 1511 1512 KASSERT(args->endp != NULL, ("endp not initialized")); 1513 1514 if (args->envc > 0) 1515 return (args->begin_envv); 1516 return (args->endp); 1517 } 1518 1519 /* 1520 * Copy strings out to the new process address space, constructing new arg 1521 * and env vector tables. Return a pointer to the base so that it can be used 1522 * as the initial stack pointer. 1523 */ 1524 int 1525 exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base) 1526 { 1527 int argc, envc; 1528 char **vectp; 1529 char *stringp; 1530 uintptr_t destp, ustringp; 1531 struct ps_strings *arginfo; 1532 struct proc *p; 1533 size_t execpath_len; 1534 int error, szsigcode, szps; 1535 char canary[sizeof(long) * 8]; 1536 1537 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1538 /* 1539 * Calculate string base and vector table pointers. 1540 * Also deal with signal trampoline code for this exec type. 1541 */ 1542 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1543 execpath_len = strlen(imgp->execpath) + 1; 1544 else 1545 execpath_len = 0; 1546 p = imgp->proc; 1547 szsigcode = 0; 1548 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1549 imgp->ps_strings = arginfo; 1550 if (p->p_sysent->sv_sigcode_base == 0) { 1551 if (p->p_sysent->sv_szsigcode != NULL) 1552 szsigcode = *(p->p_sysent->sv_szsigcode); 1553 } 1554 destp = (uintptr_t)arginfo; 1555 1556 /* 1557 * install sigcode 1558 */ 1559 if (szsigcode != 0) { 1560 destp -= szsigcode; 1561 destp = rounddown2(destp, sizeof(void *)); 1562 error = copyout(p->p_sysent->sv_sigcode, (void *)destp, 1563 szsigcode); 1564 if (error != 0) 1565 return (error); 1566 } 1567 1568 /* 1569 * Copy the image path for the rtld. 1570 */ 1571 if (execpath_len != 0) { 1572 destp -= execpath_len; 1573 destp = rounddown2(destp, sizeof(void *)); 1574 imgp->execpathp = (void *)destp; 1575 error = copyout(imgp->execpath, imgp->execpathp, execpath_len); 1576 if (error != 0) 1577 return (error); 1578 } 1579 1580 /* 1581 * Prepare the canary for SSP. 1582 */ 1583 arc4rand(canary, sizeof(canary), 0); 1584 destp -= sizeof(canary); 1585 imgp->canary = (void *)destp; 1586 error = copyout(canary, imgp->canary, sizeof(canary)); 1587 if (error != 0) 1588 return (error); 1589 imgp->canarylen = sizeof(canary); 1590 1591 /* 1592 * Prepare the pagesizes array. 1593 */ 1594 destp -= szps; 1595 destp = rounddown2(destp, sizeof(void *)); 1596 imgp->pagesizes = (void *)destp; 1597 error = copyout(pagesizes, imgp->pagesizes, szps); 1598 if (error != 0) 1599 return (error); 1600 imgp->pagesizeslen = szps; 1601 1602 /* 1603 * Allocate room for the argument and environment strings. 1604 */ 1605 destp -= ARG_MAX - imgp->args->stringspace; 1606 destp = rounddown2(destp, sizeof(void *)); 1607 ustringp = destp; 1608 1609 if (imgp->sysent->sv_stackgap != NULL) 1610 imgp->sysent->sv_stackgap(imgp, &destp); 1611 1612 if (imgp->auxargs) { 1613 /* 1614 * Allocate room on the stack for the ELF auxargs 1615 * array. It has up to AT_COUNT entries. 1616 */ 1617 destp -= AT_COUNT * sizeof(Elf_Auxinfo); 1618 destp = rounddown2(destp, sizeof(void *)); 1619 } 1620 1621 vectp = (char **)destp; 1622 1623 /* 1624 * Allocate room for the argv[] and env vectors including the 1625 * terminating NULL pointers. 1626 */ 1627 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1628 1629 /* 1630 * vectp also becomes our initial stack base 1631 */ 1632 *stack_base = (uintptr_t)vectp; 1633 1634 stringp = imgp->args->begin_argv; 1635 argc = imgp->args->argc; 1636 envc = imgp->args->envc; 1637 1638 /* 1639 * Copy out strings - arguments and environment. 1640 */ 1641 error = copyout(stringp, (void *)ustringp, 1642 ARG_MAX - imgp->args->stringspace); 1643 if (error != 0) 1644 return (error); 1645 1646 /* 1647 * Fill in "ps_strings" struct for ps, w, etc. 1648 */ 1649 imgp->argv = vectp; 1650 if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 || 1651 suword32(&arginfo->ps_nargvstr, argc) != 0) 1652 return (EFAULT); 1653 1654 /* 1655 * Fill in argument portion of vector table. 1656 */ 1657 for (; argc > 0; --argc) { 1658 if (suword(vectp++, ustringp) != 0) 1659 return (EFAULT); 1660 while (*stringp++ != 0) 1661 ustringp++; 1662 ustringp++; 1663 } 1664 1665 /* a null vector table pointer separates the argp's from the envp's */ 1666 if (suword(vectp++, 0) != 0) 1667 return (EFAULT); 1668 1669 imgp->envv = vectp; 1670 if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 || 1671 suword32(&arginfo->ps_nenvstr, envc) != 0) 1672 return (EFAULT); 1673 1674 /* 1675 * Fill in environment portion of vector table. 1676 */ 1677 for (; envc > 0; --envc) { 1678 if (suword(vectp++, ustringp) != 0) 1679 return (EFAULT); 1680 while (*stringp++ != 0) 1681 ustringp++; 1682 ustringp++; 1683 } 1684 1685 /* end of vector table is a null pointer */ 1686 if (suword(vectp, 0) != 0) 1687 return (EFAULT); 1688 1689 if (imgp->auxargs) { 1690 vectp++; 1691 error = imgp->sysent->sv_copyout_auxargs(imgp, 1692 (uintptr_t)vectp); 1693 if (error != 0) 1694 return (error); 1695 } 1696 1697 return (0); 1698 } 1699 1700 /* 1701 * Check permissions of file to execute. 1702 * Called with imgp->vp locked. 1703 * Return 0 for success or error code on failure. 1704 */ 1705 int 1706 exec_check_permissions(struct image_params *imgp) 1707 { 1708 struct vnode *vp = imgp->vp; 1709 struct vattr *attr = imgp->attr; 1710 struct thread *td; 1711 int error; 1712 1713 td = curthread; 1714 1715 /* Get file attributes */ 1716 error = VOP_GETATTR(vp, attr, td->td_ucred); 1717 if (error) 1718 return (error); 1719 1720 #ifdef MAC 1721 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1722 if (error) 1723 return (error); 1724 #endif 1725 1726 /* 1727 * 1) Check if file execution is disabled for the filesystem that 1728 * this file resides on. 1729 * 2) Ensure that at least one execute bit is on. Otherwise, a 1730 * privileged user will always succeed, and we don't want this 1731 * to happen unless the file really is executable. 1732 * 3) Ensure that the file is a regular file. 1733 */ 1734 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1735 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1736 (attr->va_type != VREG)) 1737 return (EACCES); 1738 1739 /* 1740 * Zero length files can't be exec'd 1741 */ 1742 if (attr->va_size == 0) 1743 return (ENOEXEC); 1744 1745 /* 1746 * Check for execute permission to file based on current credentials. 1747 */ 1748 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1749 if (error) 1750 return (error); 1751 1752 /* 1753 * Check number of open-for-writes on the file and deny execution 1754 * if there are any. 1755 * 1756 * Add a text reference now so no one can write to the 1757 * executable while we're activating it. 1758 * 1759 * Remember if this was set before and unset it in case this is not 1760 * actually an executable image. 1761 */ 1762 error = VOP_SET_TEXT(vp); 1763 if (error != 0) 1764 return (error); 1765 imgp->textset = true; 1766 1767 /* 1768 * Call filesystem specific open routine (which does nothing in the 1769 * general case). 1770 */ 1771 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1772 if (error == 0) 1773 imgp->opened = 1; 1774 return (error); 1775 } 1776 1777 /* 1778 * Exec handler registration 1779 */ 1780 int 1781 exec_register(const struct execsw *execsw_arg) 1782 { 1783 const struct execsw **es, **xs, **newexecsw; 1784 u_int count = 2; /* New slot and trailing NULL */ 1785 1786 if (execsw) 1787 for (es = execsw; *es; es++) 1788 count++; 1789 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1790 xs = newexecsw; 1791 if (execsw) 1792 for (es = execsw; *es; es++) 1793 *xs++ = *es; 1794 *xs++ = execsw_arg; 1795 *xs = NULL; 1796 if (execsw) 1797 free(execsw, M_TEMP); 1798 execsw = newexecsw; 1799 return (0); 1800 } 1801 1802 int 1803 exec_unregister(const struct execsw *execsw_arg) 1804 { 1805 const struct execsw **es, **xs, **newexecsw; 1806 int count = 1; 1807 1808 if (execsw == NULL) 1809 panic("unregister with no handlers left?\n"); 1810 1811 for (es = execsw; *es; es++) { 1812 if (*es == execsw_arg) 1813 break; 1814 } 1815 if (*es == NULL) 1816 return (ENOENT); 1817 for (es = execsw; *es; es++) 1818 if (*es != execsw_arg) 1819 count++; 1820 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1821 xs = newexecsw; 1822 for (es = execsw; *es; es++) 1823 if (*es != execsw_arg) 1824 *xs++ = *es; 1825 *xs = NULL; 1826 if (execsw) 1827 free(execsw, M_TEMP); 1828 execsw = newexecsw; 1829 return (0); 1830 } 1831