Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exec.c
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1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD: releng/11.2/sys/kern/kern_exec.c 333162 2018-05-02 07:57:36Z kib $"); 29 30 #include "opt_capsicum.h" 31 #include "opt_hwpmc_hooks.h" 32 #include "opt_ktrace.h" 33 #include "opt_vm.h" 34 35 #include <sys/param.h> 36 #include <sys/capsicum.h> 37 #include <sys/systm.h> 38 #include <sys/eventhandler.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/sysproto.h> 42 #include <sys/signalvar.h> 43 #include <sys/kernel.h> 44 #include <sys/mount.h> 45 #include <sys/filedesc.h> 46 #include <sys/fcntl.h> 47 #include <sys/acct.h> 48 #include <sys/exec.h> 49 #include <sys/imgact.h> 50 #include <sys/imgact_elf.h> 51 #include <sys/wait.h> 52 #include <sys/malloc.h> 53 #include <sys/mman.h> 54 #include <sys/priv.h> 55 #include <sys/proc.h> 56 #include <sys/pioctl.h> 57 #include <sys/ptrace.h> 58 #include <sys/namei.h> 59 #include <sys/resourcevar.h> 60 #include <sys/rwlock.h> 61 #include <sys/sched.h> 62 #include <sys/sdt.h> 63 #include <sys/sf_buf.h> 64 #include <sys/syscallsubr.h> 65 #include <sys/sysent.h> 66 #include <sys/shm.h> 67 #include <sys/smp.h> 68 #include <sys/sysctl.h> 69 #include <sys/vnode.h> 70 #include <sys/stat.h> 71 #ifdef KTRACE 72 #include <sys/ktrace.h> 73 #endif 74 75 #include <vm/vm.h> 76 #include <vm/vm_param.h> 77 #include <vm/pmap.h> 78 #include <vm/vm_page.h> 79 #include <vm/vm_map.h> 80 #include <vm/vm_kern.h> 81 #include <vm/vm_extern.h> 82 #include <vm/vm_object.h> 83 #include <vm/vm_pager.h> 84 85 #ifdef HWPMC_HOOKS 86 #include <sys/pmckern.h> 87 #endif 88 89 #include <machine/reg.h> 90 91 #include <security/audit/audit.h> 92 #include <security/mac/mac_framework.h> 93 94 #ifdef KDTRACE_HOOKS 95 #include <sys/dtrace_bsd.h> 96 dtrace_execexit_func_t dtrace_fasttrap_exec; 97 #endif 98 99 SDT_PROVIDER_DECLARE(proc); 100 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 101 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 102 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 103 104 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 105 106 int coredump_pack_fileinfo = 1; 107 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 108 &coredump_pack_fileinfo, 0, 109 "Enable file path packing in 'procstat -f' coredump notes"); 110 111 int coredump_pack_vmmapinfo = 1; 112 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 113 &coredump_pack_vmmapinfo, 0, 114 "Enable file path packing in 'procstat -v' coredump notes"); 115 116 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 117 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 118 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 119 static int do_execve(struct thread *td, struct image_args *args, 120 struct mac *mac_p); 121 122 /* XXX This should be vm_size_t. */ 123 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 124 CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", ""); 125 126 /* XXX This should be vm_size_t. */ 127 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 128 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", ""); 129 130 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 131 NULL, 0, sysctl_kern_stackprot, "I", ""); 132 133 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 134 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 135 &ps_arg_cache_limit, 0, ""); 136 137 static int disallow_high_osrel; 138 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 139 &disallow_high_osrel, 0, 140 "Disallow execution of binaries built for higher version of the world"); 141 142 static int map_at_zero = 0; 143 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 144 "Permit processes to map an object at virtual address 0."); 145 146 EVENTHANDLER_LIST_DECLARE(process_exec); 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 == 0) 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 args->begin_envv - args->begin_argv); 347 AUDIT_ARG_ENVV(args->begin_envv, args->envc, 348 args->endp - args->begin_envv); 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 cap_rights_t rights; 376 int credential_changing; 377 int textset; 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 static const char fexecv_proc_title[] = "(fexecv)"; 386 387 imgp = &image_params; 388 389 /* 390 * Lock the process and set the P_INEXEC flag to indicate that 391 * it should be left alone until we're done here. This is 392 * necessary to avoid race conditions - e.g. in ptrace() - 393 * that might allow a local user to illicitly obtain elevated 394 * privileges. 395 */ 396 PROC_LOCK(p); 397 KASSERT((p->p_flag & P_INEXEC) == 0, 398 ("%s(): process already has P_INEXEC flag", __func__)); 399 p->p_flag |= P_INEXEC; 400 PROC_UNLOCK(p); 401 402 /* 403 * Initialize part of the common data 404 */ 405 bzero(imgp, sizeof(*imgp)); 406 imgp->proc = p; 407 imgp->attr = &attr; 408 imgp->args = args; 409 oldcred = p->p_ucred; 410 411 #ifdef MAC 412 error = mac_execve_enter(imgp, mac_p); 413 if (error) 414 goto exec_fail; 415 #endif 416 417 /* 418 * Translate the file name. namei() returns a vnode pointer 419 * in ni_vp among other things. 420 * 421 * XXXAUDIT: It would be desirable to also audit the name of the 422 * interpreter if this is an interpreted binary. 423 */ 424 if (args->fname != NULL) { 425 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | FOLLOW | SAVENAME 426 | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 427 } 428 429 SDT_PROBE1(proc, , , exec, args->fname); 430 431 interpret: 432 if (args->fname != NULL) { 433 #ifdef CAPABILITY_MODE 434 /* 435 * While capability mode can't reach this point via direct 436 * path arguments to execve(), we also don't allow 437 * interpreters to be used in capability mode (for now). 438 * Catch indirect lookups and return a permissions error. 439 */ 440 if (IN_CAPABILITY_MODE(td)) { 441 error = ECAPMODE; 442 goto exec_fail; 443 } 444 #endif 445 error = namei(&nd); 446 if (error) 447 goto exec_fail; 448 449 newtextvp = nd.ni_vp; 450 imgp->vp = newtextvp; 451 } else { 452 AUDIT_ARG_FD(args->fd); 453 /* 454 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 455 */ 456 error = fgetvp_exec(td, args->fd, 457 cap_rights_init(&rights, CAP_FEXECVE), &newtextvp); 458 if (error) 459 goto exec_fail; 460 vn_lock(newtextvp, LK_EXCLUSIVE | LK_RETRY); 461 AUDIT_ARG_VNODE1(newtextvp); 462 imgp->vp = newtextvp; 463 } 464 465 /* 466 * Check file permissions (also 'opens' file) 467 */ 468 error = exec_check_permissions(imgp); 469 if (error) 470 goto exec_fail_dealloc; 471 472 imgp->object = imgp->vp->v_object; 473 if (imgp->object != NULL) 474 vm_object_reference(imgp->object); 475 476 /* 477 * Set VV_TEXT now so no one can write to the executable while we're 478 * activating it. 479 * 480 * Remember if this was set before and unset it in case this is not 481 * actually an executable image. 482 */ 483 textset = VOP_IS_TEXT(imgp->vp); 484 VOP_SET_TEXT(imgp->vp); 485 486 error = exec_map_first_page(imgp); 487 if (error) 488 goto exec_fail_dealloc; 489 490 imgp->proc->p_osrel = 0; 491 492 /* 493 * Implement image setuid/setgid. 494 * 495 * Determine new credentials before attempting image activators 496 * so that it can be used by process_exec handlers to determine 497 * credential/setid changes. 498 * 499 * Don't honor setuid/setgid if the filesystem prohibits it or if 500 * the process is being traced. 501 * 502 * We disable setuid/setgid/etc in capability mode on the basis 503 * that most setugid applications are not written with that 504 * environment in mind, and will therefore almost certainly operate 505 * incorrectly. In principle there's no reason that setugid 506 * applications might not be useful in capability mode, so we may want 507 * to reconsider this conservative design choice in the future. 508 * 509 * XXXMAC: For the time being, use NOSUID to also prohibit 510 * transitions on the file system. 511 */ 512 credential_changing = 0; 513 credential_changing |= (attr.va_mode & S_ISUID) && 514 oldcred->cr_uid != attr.va_uid; 515 credential_changing |= (attr.va_mode & S_ISGID) && 516 oldcred->cr_gid != attr.va_gid; 517 #ifdef MAC 518 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 519 interpvplabel, imgp); 520 credential_changing |= will_transition; 521 #endif 522 523 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 524 if (credential_changing) 525 imgp->proc->p_pdeathsig = 0; 526 527 if (credential_changing && 528 #ifdef CAPABILITY_MODE 529 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 530 #endif 531 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 532 (p->p_flag & P_TRACED) == 0) { 533 imgp->credential_setid = true; 534 VOP_UNLOCK(imgp->vp, 0); 535 imgp->newcred = crdup(oldcred); 536 if (attr.va_mode & S_ISUID) { 537 euip = uifind(attr.va_uid); 538 change_euid(imgp->newcred, euip); 539 } 540 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 541 if (attr.va_mode & S_ISGID) 542 change_egid(imgp->newcred, attr.va_gid); 543 /* 544 * Implement correct POSIX saved-id behavior. 545 * 546 * XXXMAC: Note that the current logic will save the 547 * uid and gid if a MAC domain transition occurs, even 548 * though maybe it shouldn't. 549 */ 550 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 551 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 552 } else { 553 /* 554 * Implement correct POSIX saved-id behavior. 555 * 556 * XXX: It's not clear that the existing behavior is 557 * POSIX-compliant. A number of sources indicate that the 558 * saved uid/gid should only be updated if the new ruid is 559 * not equal to the old ruid, or the new euid is not equal 560 * to the old euid and the new euid is not equal to the old 561 * ruid. The FreeBSD code always updates the saved uid/gid. 562 * Also, this code uses the new (replaced) euid and egid as 563 * the source, which may or may not be the right ones to use. 564 */ 565 if (oldcred->cr_svuid != oldcred->cr_uid || 566 oldcred->cr_svgid != oldcred->cr_gid) { 567 VOP_UNLOCK(imgp->vp, 0); 568 imgp->newcred = crdup(oldcred); 569 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 570 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 571 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 572 } 573 } 574 /* The new credentials are installed into the process later. */ 575 576 /* 577 * Do the best to calculate the full path to the image file. 578 */ 579 if (args->fname != NULL && args->fname[0] == '/') 580 imgp->execpath = args->fname; 581 else { 582 VOP_UNLOCK(imgp->vp, 0); 583 if (vn_fullpath(td, imgp->vp, &imgp->execpath, 584 &imgp->freepath) != 0) 585 imgp->execpath = args->fname; 586 vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY); 587 } 588 589 /* 590 * If the current process has a special image activator it 591 * wants to try first, call it. For example, emulating shell 592 * scripts differently. 593 */ 594 error = -1; 595 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 596 error = img_first(imgp); 597 598 /* 599 * Loop through the list of image activators, calling each one. 600 * An activator returns -1 if there is no match, 0 on success, 601 * and an error otherwise. 602 */ 603 for (i = 0; error == -1 && execsw[i]; ++i) { 604 if (execsw[i]->ex_imgact == NULL || 605 execsw[i]->ex_imgact == img_first) { 606 continue; 607 } 608 error = (*execsw[i]->ex_imgact)(imgp); 609 } 610 611 if (error) { 612 if (error == -1) { 613 if (textset == 0) 614 VOP_UNSET_TEXT(imgp->vp); 615 error = ENOEXEC; 616 } 617 goto exec_fail_dealloc; 618 } 619 620 /* 621 * Special interpreter operation, cleanup and loop up to try to 622 * activate the interpreter. 623 */ 624 if (imgp->interpreted) { 625 exec_unmap_first_page(imgp); 626 /* 627 * VV_TEXT needs to be unset for scripts. There is a short 628 * period before we determine that something is a script where 629 * VV_TEXT will be set. The vnode lock is held over this 630 * entire period so nothing should illegitimately be blocked. 631 */ 632 VOP_UNSET_TEXT(imgp->vp); 633 /* free name buffer and old vnode */ 634 if (args->fname != NULL) 635 NDFREE(&nd, NDF_ONLY_PNBUF); 636 #ifdef MAC 637 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 638 #endif 639 if (imgp->opened) { 640 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 641 imgp->opened = 0; 642 } 643 vput(newtextvp); 644 vm_object_deallocate(imgp->object); 645 imgp->object = NULL; 646 imgp->credential_setid = false; 647 if (imgp->newcred != NULL) { 648 crfree(imgp->newcred); 649 imgp->newcred = NULL; 650 } 651 imgp->execpath = NULL; 652 free(imgp->freepath, M_TEMP); 653 imgp->freepath = NULL; 654 /* set new name to that of the interpreter */ 655 NDINIT(&nd, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 656 UIO_SYSSPACE, imgp->interpreter_name, td); 657 args->fname = imgp->interpreter_name; 658 goto interpret; 659 } 660 661 /* 662 * NB: We unlock the vnode here because it is believed that none 663 * of the sv_copyout_strings/sv_fixup operations require the vnode. 664 */ 665 VOP_UNLOCK(imgp->vp, 0); 666 667 if (disallow_high_osrel && 668 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 669 error = ENOEXEC; 670 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 671 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 672 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 673 goto exec_fail_dealloc; 674 } 675 676 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 677 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 678 sys_cap_enter(td, NULL); 679 680 /* 681 * Copy out strings (args and env) and initialize stack base 682 */ 683 if (p->p_sysent->sv_copyout_strings) 684 stack_base = (*p->p_sysent->sv_copyout_strings)(imgp); 685 else 686 stack_base = exec_copyout_strings(imgp); 687 688 /* 689 * If custom stack fixup routine present for this process 690 * let it do the stack setup. 691 * Else stuff argument count as first item on stack 692 */ 693 if (p->p_sysent->sv_fixup != NULL) 694 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 695 else 696 suword(--stack_base, imgp->args->argc); 697 698 if (args->fdp != NULL) { 699 /* Install a brand new file descriptor table. */ 700 fdinstall_remapped(td, args->fdp); 701 args->fdp = NULL; 702 } else { 703 /* 704 * Keep on using the existing file descriptor table. For 705 * security and other reasons, the file descriptor table 706 * cannot be shared after an exec. 707 */ 708 fdunshare(td); 709 /* close files on exec */ 710 fdcloseexec(td); 711 } 712 713 /* 714 * Malloc things before we need locks. 715 */ 716 i = imgp->args->begin_envv - imgp->args->begin_argv; 717 /* Cache arguments if they fit inside our allowance */ 718 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 719 newargs = pargs_alloc(i); 720 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 721 } 722 723 /* 724 * For security and other reasons, signal handlers cannot 725 * be shared after an exec. The new process gets a copy of the old 726 * handlers. In execsigs(), the new process will have its signals 727 * reset. 728 */ 729 if (sigacts_shared(p->p_sigacts)) { 730 oldsigacts = p->p_sigacts; 731 newsigacts = sigacts_alloc(); 732 sigacts_copy(newsigacts, oldsigacts); 733 } 734 735 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 736 737 PROC_LOCK(p); 738 if (oldsigacts) 739 p->p_sigacts = newsigacts; 740 /* Stop profiling */ 741 stopprofclock(p); 742 743 /* reset caught signals */ 744 execsigs(p); 745 746 /* name this process - nameiexec(p, ndp) */ 747 bzero(p->p_comm, sizeof(p->p_comm)); 748 if (args->fname) 749 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 750 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 751 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 752 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 753 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 754 #ifdef KTR 755 sched_clear_tdname(td); 756 #endif 757 758 /* 759 * mark as execed, wakeup the process that vforked (if any) and tell 760 * it that it now has its own resources back 761 */ 762 p->p_flag |= P_EXEC; 763 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 764 p->p_flag2 &= ~P2_NOTRACE; 765 if (p->p_flag & P_PPWAIT) { 766 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 767 cv_broadcast(&p->p_pwait); 768 /* STOPs are no longer ignored, arrange for AST */ 769 signotify(td); 770 } 771 772 /* 773 * Implement image setuid/setgid installation. 774 */ 775 if (imgp->credential_setid) { 776 /* 777 * Turn off syscall tracing for set-id programs, except for 778 * root. Record any set-id flags first to make sure that 779 * we do not regain any tracing during a possible block. 780 */ 781 setsugid(p); 782 783 #ifdef KTRACE 784 if (p->p_tracecred != NULL && 785 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED, 0)) 786 ktrprocexec(p, &tracecred, &tracevp); 787 #endif 788 /* 789 * Close any file descriptors 0..2 that reference procfs, 790 * then make sure file descriptors 0..2 are in use. 791 * 792 * Both fdsetugidsafety() and fdcheckstd() may call functions 793 * taking sleepable locks, so temporarily drop our locks. 794 */ 795 PROC_UNLOCK(p); 796 VOP_UNLOCK(imgp->vp, 0); 797 fdsetugidsafety(td); 798 error = fdcheckstd(td); 799 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 800 if (error != 0) 801 goto exec_fail_dealloc; 802 PROC_LOCK(p); 803 #ifdef MAC 804 if (will_transition) { 805 mac_vnode_execve_transition(oldcred, imgp->newcred, 806 imgp->vp, interpvplabel, imgp); 807 } 808 #endif 809 } else { 810 if (oldcred->cr_uid == oldcred->cr_ruid && 811 oldcred->cr_gid == oldcred->cr_rgid) 812 p->p_flag &= ~P_SUGID; 813 } 814 /* 815 * Set the new credentials. 816 */ 817 if (imgp->newcred != NULL) { 818 proc_set_cred(p, imgp->newcred); 819 crfree(oldcred); 820 oldcred = NULL; 821 } 822 823 /* 824 * Store the vp for use in procfs. This vnode was referenced by namei 825 * or fgetvp_exec. 826 */ 827 oldtextvp = p->p_textvp; 828 p->p_textvp = newtextvp; 829 830 #ifdef KDTRACE_HOOKS 831 /* 832 * Tell the DTrace fasttrap provider about the exec if it 833 * has declared an interest. 834 */ 835 if (dtrace_fasttrap_exec) 836 dtrace_fasttrap_exec(p); 837 #endif 838 839 /* 840 * Notify others that we exec'd, and clear the P_INEXEC flag 841 * as we're now a bona fide freshly-execed process. 842 */ 843 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 844 p->p_flag &= ~P_INEXEC; 845 846 /* clear "fork but no exec" flag, as we _are_ execing */ 847 p->p_acflag &= ~AFORK; 848 849 /* 850 * Free any previous argument cache and replace it with 851 * the new argument cache, if any. 852 */ 853 oldargs = p->p_args; 854 p->p_args = newargs; 855 newargs = NULL; 856 857 #ifdef HWPMC_HOOKS 858 /* 859 * Check if system-wide sampling is in effect or if the 860 * current process is using PMCs. If so, do exec() time 861 * processing. This processing needs to happen AFTER the 862 * P_INEXEC flag is cleared. 863 * 864 * The proc lock needs to be released before taking the PMC 865 * SX. 866 */ 867 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 868 PROC_UNLOCK(p); 869 VOP_UNLOCK(imgp->vp, 0); 870 pe.pm_credentialschanged = credential_changing; 871 pe.pm_entryaddr = imgp->entry_addr; 872 873 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 874 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 875 } else 876 PROC_UNLOCK(p); 877 #else /* !HWPMC_HOOKS */ 878 PROC_UNLOCK(p); 879 #endif 880 881 /* Set values passed into the program in registers. */ 882 if (p->p_sysent->sv_setregs) 883 (*p->p_sysent->sv_setregs)(td, imgp, 884 (u_long)(uintptr_t)stack_base); 885 else 886 exec_setregs(td, imgp, (u_long)(uintptr_t)stack_base); 887 888 vfs_mark_atime(imgp->vp, td->td_ucred); 889 890 SDT_PROBE1(proc, , , exec__success, args->fname); 891 892 exec_fail_dealloc: 893 if (imgp->firstpage != NULL) 894 exec_unmap_first_page(imgp); 895 896 if (imgp->vp != NULL) { 897 if (args->fname) 898 NDFREE(&nd, NDF_ONLY_PNBUF); 899 if (imgp->opened) 900 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 901 if (error != 0) 902 vput(imgp->vp); 903 else 904 VOP_UNLOCK(imgp->vp, 0); 905 } 906 907 if (imgp->object != NULL) 908 vm_object_deallocate(imgp->object); 909 910 free(imgp->freepath, M_TEMP); 911 912 if (error == 0) { 913 PROC_LOCK(p); 914 if (p->p_ptevents & PTRACE_EXEC) 915 td->td_dbgflags |= TDB_EXEC; 916 PROC_UNLOCK(p); 917 918 /* 919 * Stop the process here if its stop event mask has 920 * the S_EXEC bit set. 921 */ 922 STOPEVENT(p, S_EXEC, 0); 923 } else { 924 exec_fail: 925 /* we're done here, clear P_INEXEC */ 926 PROC_LOCK(p); 927 p->p_flag &= ~P_INEXEC; 928 PROC_UNLOCK(p); 929 930 SDT_PROBE1(proc, , , exec__failure, error); 931 } 932 933 if (imgp->newcred != NULL && oldcred != NULL) 934 crfree(imgp->newcred); 935 936 #ifdef MAC 937 mac_execve_exit(imgp); 938 mac_execve_interpreter_exit(interpvplabel); 939 #endif 940 exec_free_args(args); 941 942 /* 943 * Handle deferred decrement of ref counts. 944 */ 945 if (oldtextvp != NULL) 946 vrele(oldtextvp); 947 #ifdef KTRACE 948 if (tracevp != NULL) 949 vrele(tracevp); 950 if (tracecred != NULL) 951 crfree(tracecred); 952 #endif 953 pargs_drop(oldargs); 954 pargs_drop(newargs); 955 if (oldsigacts != NULL) 956 sigacts_free(oldsigacts); 957 if (euip != NULL) 958 uifree(euip); 959 960 if (error && imgp->vmspace_destroyed) { 961 /* sorry, no more process anymore. exit gracefully */ 962 exit1(td, 0, SIGABRT); 963 /* NOT REACHED */ 964 } 965 966 #ifdef KTRACE 967 if (error == 0) 968 ktrprocctor(p); 969 #endif 970 971 return (error); 972 } 973 974 int 975 exec_map_first_page(imgp) 976 struct image_params *imgp; 977 { 978 int rv, i, after, initial_pagein; 979 vm_page_t ma[VM_INITIAL_PAGEIN]; 980 vm_object_t object; 981 982 if (imgp->firstpage != NULL) 983 exec_unmap_first_page(imgp); 984 985 object = imgp->vp->v_object; 986 if (object == NULL) 987 return (EACCES); 988 VM_OBJECT_WLOCK(object); 989 #if VM_NRESERVLEVEL > 0 990 vm_object_color(object, 0); 991 #endif 992 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 993 if (ma[0]->valid != VM_PAGE_BITS_ALL) { 994 vm_page_xbusy(ma[0]); 995 if (!vm_pager_has_page(object, 0, NULL, &after)) { 996 vm_page_lock(ma[0]); 997 vm_page_free(ma[0]); 998 vm_page_unlock(ma[0]); 999 VM_OBJECT_WUNLOCK(object); 1000 return (EIO); 1001 } 1002 initial_pagein = min(after, VM_INITIAL_PAGEIN); 1003 KASSERT(initial_pagein <= object->size, 1004 ("%s: initial_pagein %d object->size %ju", 1005 __func__, initial_pagein, (uintmax_t )object->size)); 1006 for (i = 1; i < initial_pagein; i++) { 1007 if ((ma[i] = vm_page_next(ma[i - 1])) != NULL) { 1008 if (ma[i]->valid) 1009 break; 1010 if (!vm_page_tryxbusy(ma[i])) 1011 break; 1012 } else { 1013 ma[i] = vm_page_alloc(object, i, 1014 VM_ALLOC_NORMAL); 1015 if (ma[i] == NULL) 1016 break; 1017 } 1018 } 1019 initial_pagein = i; 1020 rv = vm_pager_get_pages(object, ma, initial_pagein, NULL, NULL); 1021 if (rv != VM_PAGER_OK) { 1022 for (i = 0; i < initial_pagein; i++) { 1023 vm_page_lock(ma[i]); 1024 vm_page_free(ma[i]); 1025 vm_page_unlock(ma[i]); 1026 } 1027 VM_OBJECT_WUNLOCK(object); 1028 return (EIO); 1029 } 1030 vm_page_xunbusy(ma[0]); 1031 for (i = 1; i < initial_pagein; i++) 1032 vm_page_readahead_finish(ma[i]); 1033 } 1034 vm_page_lock(ma[0]); 1035 vm_page_hold(ma[0]); 1036 vm_page_activate(ma[0]); 1037 vm_page_unlock(ma[0]); 1038 VM_OBJECT_WUNLOCK(object); 1039 1040 imgp->firstpage = sf_buf_alloc(ma[0], 0); 1041 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1042 1043 return (0); 1044 } 1045 1046 void 1047 exec_unmap_first_page(struct image_params *imgp) 1048 { 1049 vm_page_t m; 1050 1051 if (imgp->firstpage != NULL) { 1052 m = sf_buf_page(imgp->firstpage); 1053 sf_buf_free(imgp->firstpage); 1054 imgp->firstpage = NULL; 1055 vm_page_lock(m); 1056 vm_page_unhold(m); 1057 vm_page_unlock(m); 1058 } 1059 } 1060 1061 /* 1062 * Destroy old address space, and allocate a new stack. 1063 * The new stack is only sgrowsiz large because it is grown 1064 * automatically on a page fault. 1065 */ 1066 int 1067 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1068 { 1069 int error; 1070 struct proc *p = imgp->proc; 1071 struct vmspace *vmspace = p->p_vmspace; 1072 vm_object_t obj; 1073 struct rlimit rlim_stack; 1074 vm_offset_t sv_minuser, stack_addr; 1075 vm_map_t map; 1076 u_long ssiz; 1077 1078 imgp->vmspace_destroyed = 1; 1079 imgp->sysent = sv; 1080 1081 /* May be called with Giant held */ 1082 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1083 1084 /* 1085 * Blow away entire process VM, if address space not shared, 1086 * otherwise, create a new VM space so that other threads are 1087 * not disrupted 1088 */ 1089 map = &vmspace->vm_map; 1090 if (map_at_zero) 1091 sv_minuser = sv->sv_minuser; 1092 else 1093 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1094 if (vmspace->vm_refcnt == 1 && vm_map_min(map) == sv_minuser && 1095 vm_map_max(map) == sv->sv_maxuser) { 1096 shmexit(vmspace); 1097 pmap_remove_pages(vmspace_pmap(vmspace)); 1098 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1099 /* An exec terminates mlockall(MCL_FUTURE). */ 1100 vm_map_lock(map); 1101 vm_map_modflags(map, 0, MAP_WIREFUTURE); 1102 vm_map_unlock(map); 1103 } else { 1104 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1105 if (error) 1106 return (error); 1107 vmspace = p->p_vmspace; 1108 map = &vmspace->vm_map; 1109 } 1110 1111 /* Map a shared page */ 1112 obj = sv->sv_shared_page_obj; 1113 if (obj != NULL) { 1114 vm_object_reference(obj); 1115 error = vm_map_fixed(map, obj, 0, 1116 sv->sv_shared_page_base, sv->sv_shared_page_len, 1117 VM_PROT_READ | VM_PROT_EXECUTE, 1118 VM_PROT_READ | VM_PROT_EXECUTE, 1119 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1120 if (error != KERN_SUCCESS) { 1121 vm_object_deallocate(obj); 1122 return (vm_mmap_to_errno(error)); 1123 } 1124 } 1125 1126 /* Allocate a new stack */ 1127 if (imgp->stack_sz != 0) { 1128 ssiz = trunc_page(imgp->stack_sz); 1129 PROC_LOCK(p); 1130 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1131 PROC_UNLOCK(p); 1132 if (ssiz > rlim_stack.rlim_max) 1133 ssiz = rlim_stack.rlim_max; 1134 if (ssiz > rlim_stack.rlim_cur) { 1135 rlim_stack.rlim_cur = ssiz; 1136 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1137 } 1138 } else if (sv->sv_maxssiz != NULL) { 1139 ssiz = *sv->sv_maxssiz; 1140 } else { 1141 ssiz = maxssiz; 1142 } 1143 stack_addr = sv->sv_usrstack - ssiz; 1144 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1145 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1146 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1147 if (error != KERN_SUCCESS) 1148 return (vm_mmap_to_errno(error)); 1149 1150 /* 1151 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1152 * are still used to enforce the stack rlimit on the process stack. 1153 */ 1154 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1155 vmspace->vm_maxsaddr = (char *)stack_addr; 1156 1157 return (0); 1158 } 1159 1160 /* 1161 * Copy out argument and environment strings from the old process address 1162 * space into the temporary string buffer. 1163 */ 1164 int 1165 exec_copyin_args(struct image_args *args, char *fname, 1166 enum uio_seg segflg, char **argv, char **envv) 1167 { 1168 u_long argp, envp; 1169 int error; 1170 size_t length; 1171 1172 bzero(args, sizeof(*args)); 1173 if (argv == NULL) 1174 return (EFAULT); 1175 1176 /* 1177 * Allocate demand-paged memory for the file name, argument, and 1178 * environment strings. 1179 */ 1180 error = exec_alloc_args(args); 1181 if (error != 0) 1182 return (error); 1183 1184 /* 1185 * Copy the file name. 1186 */ 1187 if (fname != NULL) { 1188 args->fname = args->buf; 1189 error = (segflg == UIO_SYSSPACE) ? 1190 copystr(fname, args->fname, PATH_MAX, &length) : 1191 copyinstr(fname, args->fname, PATH_MAX, &length); 1192 if (error != 0) 1193 goto err_exit; 1194 } else 1195 length = 0; 1196 1197 args->begin_argv = args->buf + length; 1198 args->endp = args->begin_argv; 1199 args->stringspace = ARG_MAX; 1200 1201 /* 1202 * extract arguments first 1203 */ 1204 for (;;) { 1205 error = fueword(argv++, &argp); 1206 if (error == -1) { 1207 error = EFAULT; 1208 goto err_exit; 1209 } 1210 if (argp == 0) 1211 break; 1212 error = copyinstr((void *)(uintptr_t)argp, args->endp, 1213 args->stringspace, &length); 1214 if (error != 0) { 1215 if (error == ENAMETOOLONG) 1216 error = E2BIG; 1217 goto err_exit; 1218 } 1219 args->stringspace -= length; 1220 args->endp += length; 1221 args->argc++; 1222 } 1223 1224 args->begin_envv = args->endp; 1225 1226 /* 1227 * extract environment strings 1228 */ 1229 if (envv) { 1230 for (;;) { 1231 error = fueword(envv++, &envp); 1232 if (error == -1) { 1233 error = EFAULT; 1234 goto err_exit; 1235 } 1236 if (envp == 0) 1237 break; 1238 error = copyinstr((void *)(uintptr_t)envp, 1239 args->endp, args->stringspace, &length); 1240 if (error != 0) { 1241 if (error == ENAMETOOLONG) 1242 error = E2BIG; 1243 goto err_exit; 1244 } 1245 args->stringspace -= length; 1246 args->endp += length; 1247 args->envc++; 1248 } 1249 } 1250 1251 return (0); 1252 1253 err_exit: 1254 exec_free_args(args); 1255 return (error); 1256 } 1257 1258 int 1259 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1260 const void *data, size_t datalen, const int *fds, size_t fdslen) 1261 { 1262 struct filedesc *ofdp; 1263 const char *p; 1264 int *kfds; 1265 int error; 1266 1267 memset(args, '\0', sizeof(*args)); 1268 ofdp = td->td_proc->p_fd; 1269 if (datalen >= ARG_MAX || fdslen > ofdp->fd_lastfile + 1) 1270 return (E2BIG); 1271 error = exec_alloc_args(args); 1272 if (error != 0) 1273 return (error); 1274 1275 args->begin_argv = args->buf; 1276 args->stringspace = ARG_MAX; 1277 1278 if (datalen > 0) { 1279 /* 1280 * Argument buffer has been provided. Copy it into the 1281 * kernel as a single string and add a terminating null 1282 * byte. 1283 */ 1284 error = copyin(data, args->begin_argv, datalen); 1285 if (error != 0) 1286 goto err_exit; 1287 args->begin_argv[datalen] = '\0'; 1288 args->endp = args->begin_argv + datalen + 1; 1289 args->stringspace -= datalen + 1; 1290 1291 /* 1292 * Traditional argument counting. Count the number of 1293 * null bytes. 1294 */ 1295 for (p = args->begin_argv; p < args->endp; ++p) 1296 if (*p == '\0') 1297 ++args->argc; 1298 } else { 1299 /* No argument buffer provided. */ 1300 args->endp = args->begin_argv; 1301 } 1302 /* There are no environment variables. */ 1303 args->begin_envv = args->endp; 1304 1305 /* Create new file descriptor table. */ 1306 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1307 error = copyin(fds, kfds, fdslen * sizeof(int)); 1308 if (error != 0) { 1309 free(kfds, M_TEMP); 1310 goto err_exit; 1311 } 1312 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1313 free(kfds, M_TEMP); 1314 if (error != 0) 1315 goto err_exit; 1316 1317 return (0); 1318 err_exit: 1319 exec_free_args(args); 1320 return (error); 1321 } 1322 1323 struct exec_args_kva { 1324 vm_offset_t addr; 1325 u_int gen; 1326 SLIST_ENTRY(exec_args_kva) next; 1327 }; 1328 1329 static DPCPU_DEFINE(struct exec_args_kva *, exec_args_kva); 1330 1331 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1332 static struct mtx exec_args_kva_mtx; 1333 static u_int exec_args_gen; 1334 1335 static void 1336 exec_prealloc_args_kva(void *arg __unused) 1337 { 1338 struct exec_args_kva *argkva; 1339 u_int i; 1340 1341 SLIST_INIT(&exec_args_kva_freelist); 1342 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1343 for (i = 0; i < exec_map_entries; i++) { 1344 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1345 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1346 argkva->gen = exec_args_gen; 1347 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1348 } 1349 } 1350 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1351 1352 static vm_offset_t 1353 exec_alloc_args_kva(void **cookie) 1354 { 1355 struct exec_args_kva *argkva; 1356 1357 argkva = (void *)atomic_readandclear_ptr( 1358 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1359 if (argkva == NULL) { 1360 mtx_lock(&exec_args_kva_mtx); 1361 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1362 (void)mtx_sleep(&exec_args_kva_freelist, 1363 &exec_args_kva_mtx, 0, "execkva", 0); 1364 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1365 mtx_unlock(&exec_args_kva_mtx); 1366 } 1367 *(struct exec_args_kva **)cookie = argkva; 1368 return (argkva->addr); 1369 } 1370 1371 static void 1372 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1373 { 1374 vm_offset_t base; 1375 1376 base = argkva->addr; 1377 if (argkva->gen != gen) { 1378 vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1379 MADV_FREE); 1380 argkva->gen = gen; 1381 } 1382 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1383 (uintptr_t)NULL, (uintptr_t)argkva)) { 1384 mtx_lock(&exec_args_kva_mtx); 1385 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1386 wakeup_one(&exec_args_kva_freelist); 1387 mtx_unlock(&exec_args_kva_mtx); 1388 } 1389 } 1390 1391 static void 1392 exec_free_args_kva(void *cookie) 1393 { 1394 1395 exec_release_args_kva(cookie, exec_args_gen); 1396 } 1397 1398 static void 1399 exec_args_kva_lowmem(void *arg __unused) 1400 { 1401 SLIST_HEAD(, exec_args_kva) head; 1402 struct exec_args_kva *argkva; 1403 u_int gen; 1404 int i; 1405 1406 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1407 1408 /* 1409 * Force an madvise of each KVA range. Any currently allocated ranges 1410 * will have MADV_FREE applied once they are freed. 1411 */ 1412 SLIST_INIT(&head); 1413 mtx_lock(&exec_args_kva_mtx); 1414 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1415 mtx_unlock(&exec_args_kva_mtx); 1416 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1417 SLIST_REMOVE_HEAD(&head, next); 1418 exec_release_args_kva(argkva, gen); 1419 } 1420 1421 CPU_FOREACH(i) { 1422 argkva = (void *)atomic_readandclear_ptr( 1423 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1424 if (argkva != NULL) 1425 exec_release_args_kva(argkva, gen); 1426 } 1427 } 1428 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1429 EVENTHANDLER_PRI_ANY); 1430 1431 /* 1432 * Allocate temporary demand-paged, zero-filled memory for the file name, 1433 * argument, and environment strings. 1434 */ 1435 int 1436 exec_alloc_args(struct image_args *args) 1437 { 1438 1439 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1440 return (0); 1441 } 1442 1443 void 1444 exec_free_args(struct image_args *args) 1445 { 1446 1447 if (args->buf != NULL) { 1448 exec_free_args_kva(args->bufkva); 1449 args->buf = NULL; 1450 } 1451 if (args->fname_buf != NULL) { 1452 free(args->fname_buf, M_TEMP); 1453 args->fname_buf = NULL; 1454 } 1455 if (args->fdp != NULL) 1456 fdescfree_remapped(args->fdp); 1457 } 1458 1459 /* 1460 * Copy strings out to the new process address space, constructing new arg 1461 * and env vector tables. Return a pointer to the base so that it can be used 1462 * as the initial stack pointer. 1463 */ 1464 register_t * 1465 exec_copyout_strings(struct image_params *imgp) 1466 { 1467 int argc, envc; 1468 char **vectp; 1469 char *stringp; 1470 uintptr_t destp; 1471 register_t *stack_base; 1472 struct ps_strings *arginfo; 1473 struct proc *p; 1474 size_t execpath_len; 1475 int szsigcode, szps; 1476 char canary[sizeof(long) * 8]; 1477 1478 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1479 /* 1480 * Calculate string base and vector table pointers. 1481 * Also deal with signal trampoline code for this exec type. 1482 */ 1483 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1484 execpath_len = strlen(imgp->execpath) + 1; 1485 else 1486 execpath_len = 0; 1487 p = imgp->proc; 1488 szsigcode = 0; 1489 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1490 if (p->p_sysent->sv_sigcode_base == 0) { 1491 if (p->p_sysent->sv_szsigcode != NULL) 1492 szsigcode = *(p->p_sysent->sv_szsigcode); 1493 } 1494 destp = (uintptr_t)arginfo; 1495 1496 /* 1497 * install sigcode 1498 */ 1499 if (szsigcode != 0) { 1500 destp -= szsigcode; 1501 destp = rounddown2(destp, sizeof(void *)); 1502 copyout(p->p_sysent->sv_sigcode, (void *)destp, szsigcode); 1503 } 1504 1505 /* 1506 * Copy the image path for the rtld. 1507 */ 1508 if (execpath_len != 0) { 1509 destp -= execpath_len; 1510 imgp->execpathp = destp; 1511 copyout(imgp->execpath, (void *)destp, execpath_len); 1512 } 1513 1514 /* 1515 * Prepare the canary for SSP. 1516 */ 1517 arc4rand(canary, sizeof(canary), 0); 1518 destp -= sizeof(canary); 1519 imgp->canary = destp; 1520 copyout(canary, (void *)destp, sizeof(canary)); 1521 imgp->canarylen = sizeof(canary); 1522 1523 /* 1524 * Prepare the pagesizes array. 1525 */ 1526 destp -= szps; 1527 destp = rounddown2(destp, sizeof(void *)); 1528 imgp->pagesizes = destp; 1529 copyout(pagesizes, (void *)destp, szps); 1530 imgp->pagesizeslen = szps; 1531 1532 destp -= ARG_MAX - imgp->args->stringspace; 1533 destp = rounddown2(destp, sizeof(void *)); 1534 1535 /* 1536 * If we have a valid auxargs ptr, prepare some room 1537 * on the stack. 1538 */ 1539 if (imgp->auxargs) { 1540 /* 1541 * 'AT_COUNT*2' is size for the ELF Auxargs data. This is for 1542 * lower compatibility. 1543 */ 1544 imgp->auxarg_size = (imgp->auxarg_size) ? imgp->auxarg_size : 1545 (AT_COUNT * 2); 1546 /* 1547 * The '+ 2' is for the null pointers at the end of each of 1548 * the arg and env vector sets,and imgp->auxarg_size is room 1549 * for argument of Runtime loader. 1550 */ 1551 vectp = (char **)(destp - (imgp->args->argc + 1552 imgp->args->envc + 2 + imgp->auxarg_size) 1553 * sizeof(char *)); 1554 } else { 1555 /* 1556 * The '+ 2' is for the null pointers at the end of each of 1557 * the arg and env vector sets 1558 */ 1559 vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc 1560 + 2) * sizeof(char *)); 1561 } 1562 1563 /* 1564 * vectp also becomes our initial stack base 1565 */ 1566 stack_base = (register_t *)vectp; 1567 1568 stringp = imgp->args->begin_argv; 1569 argc = imgp->args->argc; 1570 envc = imgp->args->envc; 1571 1572 /* 1573 * Copy out strings - arguments and environment. 1574 */ 1575 copyout(stringp, (void *)destp, ARG_MAX - imgp->args->stringspace); 1576 1577 /* 1578 * Fill in "ps_strings" struct for ps, w, etc. 1579 */ 1580 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 1581 suword32(&arginfo->ps_nargvstr, argc); 1582 1583 /* 1584 * Fill in argument portion of vector table. 1585 */ 1586 for (; argc > 0; --argc) { 1587 suword(vectp++, (long)(intptr_t)destp); 1588 while (*stringp++ != 0) 1589 destp++; 1590 destp++; 1591 } 1592 1593 /* a null vector table pointer separates the argp's from the envp's */ 1594 suword(vectp++, 0); 1595 1596 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 1597 suword32(&arginfo->ps_nenvstr, envc); 1598 1599 /* 1600 * Fill in environment portion of vector table. 1601 */ 1602 for (; envc > 0; --envc) { 1603 suword(vectp++, (long)(intptr_t)destp); 1604 while (*stringp++ != 0) 1605 destp++; 1606 destp++; 1607 } 1608 1609 /* end of vector table is a null pointer */ 1610 suword(vectp, 0); 1611 1612 return (stack_base); 1613 } 1614 1615 /* 1616 * Check permissions of file to execute. 1617 * Called with imgp->vp locked. 1618 * Return 0 for success or error code on failure. 1619 */ 1620 int 1621 exec_check_permissions(struct image_params *imgp) 1622 { 1623 struct vnode *vp = imgp->vp; 1624 struct vattr *attr = imgp->attr; 1625 struct thread *td; 1626 int error, writecount; 1627 1628 td = curthread; 1629 1630 /* Get file attributes */ 1631 error = VOP_GETATTR(vp, attr, td->td_ucred); 1632 if (error) 1633 return (error); 1634 1635 #ifdef MAC 1636 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1637 if (error) 1638 return (error); 1639 #endif 1640 1641 /* 1642 * 1) Check if file execution is disabled for the filesystem that 1643 * this file resides on. 1644 * 2) Ensure that at least one execute bit is on. Otherwise, a 1645 * privileged user will always succeed, and we don't want this 1646 * to happen unless the file really is executable. 1647 * 3) Ensure that the file is a regular file. 1648 */ 1649 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1650 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1651 (attr->va_type != VREG)) 1652 return (EACCES); 1653 1654 /* 1655 * Zero length files can't be exec'd 1656 */ 1657 if (attr->va_size == 0) 1658 return (ENOEXEC); 1659 1660 /* 1661 * Check for execute permission to file based on current credentials. 1662 */ 1663 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1664 if (error) 1665 return (error); 1666 1667 /* 1668 * Check number of open-for-writes on the file and deny execution 1669 * if there are any. 1670 */ 1671 error = VOP_GET_WRITECOUNT(vp, &writecount); 1672 if (error != 0) 1673 return (error); 1674 if (writecount != 0) 1675 return (ETXTBSY); 1676 1677 /* 1678 * Call filesystem specific open routine (which does nothing in the 1679 * general case). 1680 */ 1681 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1682 if (error == 0) 1683 imgp->opened = 1; 1684 return (error); 1685 } 1686 1687 /* 1688 * Exec handler registration 1689 */ 1690 int 1691 exec_register(const struct execsw *execsw_arg) 1692 { 1693 const struct execsw **es, **xs, **newexecsw; 1694 int count = 2; /* New slot and trailing NULL */ 1695 1696 if (execsw) 1697 for (es = execsw; *es; es++) 1698 count++; 1699 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1700 xs = newexecsw; 1701 if (execsw) 1702 for (es = execsw; *es; es++) 1703 *xs++ = *es; 1704 *xs++ = execsw_arg; 1705 *xs = NULL; 1706 if (execsw) 1707 free(execsw, M_TEMP); 1708 execsw = newexecsw; 1709 return (0); 1710 } 1711 1712 int 1713 exec_unregister(const struct execsw *execsw_arg) 1714 { 1715 const struct execsw **es, **xs, **newexecsw; 1716 int count = 1; 1717 1718 if (execsw == NULL) 1719 panic("unregister with no handlers left?\n"); 1720 1721 for (es = execsw; *es; es++) { 1722 if (*es == execsw_arg) 1723 break; 1724 } 1725 if (*es == NULL) 1726 return (ENOENT); 1727 for (es = execsw; *es; es++) 1728 if (*es != execsw_arg) 1729 count++; 1730 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1731 xs = newexecsw; 1732 for (es = execsw; *es; es++) 1733 if (*es != execsw_arg) 1734 *xs++ = *es; 1735 *xs = NULL; 1736 if (execsw) 1737 free(execsw, M_TEMP); 1738 execsw = newexecsw; 1739 return (0); 1740 }
Cache object: bfc82889c4af0043ecee52741129210f
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