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, struct vmspace *oldvmspace); 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, oldvmspace); 227 post_execve(td, error, oldvmspace); 228 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 229 return (error); 230 } 231 232 #ifndef _SYS_SYSPROTO_H_ 233 struct fexecve_args { 234 int fd; 235 char **argv; 236 char **envv; 237 }; 238 #endif 239 int 240 sys_fexecve(struct thread *td, struct fexecve_args *uap) 241 { 242 struct image_args args; 243 struct vmspace *oldvmspace; 244 int error; 245 246 error = pre_execve(td, &oldvmspace); 247 if (error != 0) 248 return (error); 249 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 250 uap->argv, uap->envv); 251 if (error == 0) { 252 args.fd = uap->fd; 253 error = kern_execve(td, &args, NULL, oldvmspace); 254 } 255 post_execve(td, error, oldvmspace); 256 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 257 return (error); 258 } 259 260 #ifndef _SYS_SYSPROTO_H_ 261 struct __mac_execve_args { 262 char *fname; 263 char **argv; 264 char **envv; 265 struct mac *mac_p; 266 }; 267 #endif 268 269 int 270 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 271 { 272 #ifdef MAC 273 struct image_args args; 274 struct vmspace *oldvmspace; 275 int error; 276 277 error = pre_execve(td, &oldvmspace); 278 if (error != 0) 279 return (error); 280 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 281 uap->argv, uap->envv); 282 if (error == 0) 283 error = kern_execve(td, &args, uap->mac_p, oldvmspace); 284 post_execve(td, error, oldvmspace); 285 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 286 return (error); 287 #else 288 return (ENOSYS); 289 #endif 290 } 291 292 int 293 pre_execve(struct thread *td, struct vmspace **oldvmspace) 294 { 295 struct proc *p; 296 int error; 297 298 KASSERT(td == curthread, ("non-current thread %p", td)); 299 error = 0; 300 p = td->td_proc; 301 if ((p->p_flag & P_HADTHREADS) != 0) { 302 PROC_LOCK(p); 303 if (thread_single(p, SINGLE_BOUNDARY) != 0) 304 error = ERESTART; 305 PROC_UNLOCK(p); 306 } 307 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 308 ("nested execve")); 309 *oldvmspace = p->p_vmspace; 310 return (error); 311 } 312 313 void 314 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 315 { 316 struct proc *p; 317 318 KASSERT(td == curthread, ("non-current thread %p", td)); 319 p = td->td_proc; 320 if ((p->p_flag & P_HADTHREADS) != 0) { 321 PROC_LOCK(p); 322 /* 323 * If success, we upgrade to SINGLE_EXIT state to 324 * force other threads to suicide. 325 */ 326 if (error == EJUSTRETURN) 327 thread_single(p, SINGLE_EXIT); 328 else 329 thread_single_end(p, SINGLE_BOUNDARY); 330 PROC_UNLOCK(p); 331 } 332 exec_cleanup(td, oldvmspace); 333 } 334 335 /* 336 * kern_execve() has the astonishing property of not always returning to 337 * the caller. If sufficiently bad things happen during the call to 338 * do_execve(), it can end up calling exit1(); as a result, callers must 339 * avoid doing anything which they might need to undo (e.g., allocating 340 * memory). 341 */ 342 int 343 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 344 struct vmspace *oldvmspace) 345 { 346 347 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 348 exec_args_get_begin_envv(args) - args->begin_argv); 349 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc, 350 args->endp - exec_args_get_begin_envv(args)); 351 return (do_execve(td, args, mac_p, oldvmspace)); 352 } 353 354 /* 355 * In-kernel implementation of execve(). All arguments are assumed to be 356 * userspace pointers from the passed thread. 357 */ 358 static int 359 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 360 struct vmspace *oldvmspace) 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(imgp->vp, &imgp->execpath, &imgp->freepath) != 0) 579 imgp->execpath = args->fname; 580 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 581 } 582 583 /* 584 * If the current process has a special image activator it 585 * wants to try first, call it. For example, emulating shell 586 * scripts differently. 587 */ 588 error = -1; 589 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 590 error = img_first(imgp); 591 592 /* 593 * Loop through the list of image activators, calling each one. 594 * An activator returns -1 if there is no match, 0 on success, 595 * and an error otherwise. 596 */ 597 for (i = 0; error == -1 && execsw[i]; ++i) { 598 if (execsw[i]->ex_imgact == NULL || 599 execsw[i]->ex_imgact == img_first) { 600 continue; 601 } 602 error = (*execsw[i]->ex_imgact)(imgp); 603 } 604 605 if (error) { 606 if (error == -1) 607 error = ENOEXEC; 608 goto exec_fail_dealloc; 609 } 610 611 /* 612 * Special interpreter operation, cleanup and loop up to try to 613 * activate the interpreter. 614 */ 615 if (imgp->interpreted) { 616 exec_unmap_first_page(imgp); 617 /* 618 * The text reference needs to be removed for scripts. 619 * There is a short period before we determine that 620 * something is a script where text reference is active. 621 * The vnode lock is held over this entire period 622 * so nothing should illegitimately be blocked. 623 */ 624 MPASS(imgp->textset); 625 VOP_UNSET_TEXT_CHECKED(newtextvp); 626 imgp->textset = false; 627 /* free name buffer and old vnode */ 628 if (args->fname != NULL) 629 NDFREE(&nd, NDF_ONLY_PNBUF); 630 #ifdef MAC 631 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 632 #endif 633 if (imgp->opened) { 634 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 635 imgp->opened = 0; 636 } 637 vput(newtextvp); 638 vm_object_deallocate(imgp->object); 639 imgp->object = NULL; 640 imgp->credential_setid = false; 641 if (imgp->newcred != NULL) { 642 crfree(imgp->newcred); 643 imgp->newcred = NULL; 644 } 645 imgp->execpath = NULL; 646 free(imgp->freepath, M_TEMP); 647 imgp->freepath = NULL; 648 /* set new name to that of the interpreter */ 649 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 650 SAVENAME, UIO_SYSSPACE, imgp->interpreter_name, td); 651 args->fname = imgp->interpreter_name; 652 goto interpret; 653 } 654 655 /* 656 * NB: We unlock the vnode here because it is believed that none 657 * of the sv_copyout_strings/sv_fixup operations require the vnode. 658 */ 659 VOP_UNLOCK(imgp->vp); 660 661 if (disallow_high_osrel && 662 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 663 error = ENOEXEC; 664 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 665 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 666 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 667 goto exec_fail_dealloc; 668 } 669 670 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 671 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 672 sys_cap_enter(td, NULL); 673 674 /* 675 * Copy out strings (args and env) and initialize stack base. 676 */ 677 error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base); 678 if (error != 0) { 679 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 680 goto exec_fail_dealloc; 681 } 682 683 /* 684 * Stack setup. 685 */ 686 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 687 if (error != 0) { 688 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 689 goto exec_fail_dealloc; 690 } 691 692 if (args->fdp != NULL) { 693 /* Install a brand new file descriptor table. */ 694 fdinstall_remapped(td, args->fdp); 695 args->fdp = NULL; 696 } else { 697 /* 698 * Keep on using the existing file descriptor table. For 699 * security and other reasons, the file descriptor table 700 * cannot be shared after an exec. 701 */ 702 fdunshare(td); 703 /* close files on exec */ 704 fdcloseexec(td); 705 } 706 707 /* 708 * Malloc things before we need locks. 709 */ 710 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 711 /* Cache arguments if they fit inside our allowance */ 712 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 713 newargs = pargs_alloc(i); 714 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 715 } 716 717 /* 718 * For security and other reasons, signal handlers cannot 719 * be shared after an exec. The new process gets a copy of the old 720 * handlers. In execsigs(), the new process will have its signals 721 * reset. 722 */ 723 if (sigacts_shared(p->p_sigacts)) { 724 oldsigacts = p->p_sigacts; 725 newsigacts = sigacts_alloc(); 726 sigacts_copy(newsigacts, oldsigacts); 727 } 728 729 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 730 731 PROC_LOCK(p); 732 if (oldsigacts) 733 p->p_sigacts = newsigacts; 734 /* Stop profiling */ 735 stopprofclock(p); 736 737 /* reset caught signals */ 738 execsigs(p); 739 740 /* name this process - nameiexec(p, ndp) */ 741 bzero(p->p_comm, sizeof(p->p_comm)); 742 if (args->fname) 743 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 744 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 745 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 746 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 747 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 748 #ifdef KTR 749 sched_clear_tdname(td); 750 #endif 751 752 /* 753 * mark as execed, wakeup the process that vforked (if any) and tell 754 * it that it now has its own resources back 755 */ 756 p->p_flag |= P_EXEC; 757 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 758 p->p_flag2 &= ~P2_NOTRACE; 759 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 760 p->p_flag2 &= ~P2_STKGAP_DISABLE; 761 if (p->p_flag & P_PPWAIT) { 762 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 763 cv_broadcast(&p->p_pwait); 764 /* STOPs are no longer ignored, arrange for AST */ 765 signotify(td); 766 } 767 768 /* 769 * Implement image setuid/setgid installation. 770 */ 771 if (imgp->credential_setid) { 772 /* 773 * Turn off syscall tracing for set-id programs, except for 774 * root. Record any set-id flags first to make sure that 775 * we do not regain any tracing during a possible block. 776 */ 777 setsugid(p); 778 779 #ifdef KTRACE 780 if (p->p_tracecred != NULL && 781 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED)) 782 ktrprocexec(p, &tracecred, &tracevp); 783 #endif 784 /* 785 * Close any file descriptors 0..2 that reference procfs, 786 * then make sure file descriptors 0..2 are in use. 787 * 788 * Both fdsetugidsafety() and fdcheckstd() may call functions 789 * taking sleepable locks, so temporarily drop our locks. 790 */ 791 PROC_UNLOCK(p); 792 VOP_UNLOCK(imgp->vp); 793 fdsetugidsafety(td); 794 error = fdcheckstd(td); 795 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 796 if (error != 0) 797 goto exec_fail_dealloc; 798 PROC_LOCK(p); 799 #ifdef MAC 800 if (will_transition) { 801 mac_vnode_execve_transition(oldcred, imgp->newcred, 802 imgp->vp, interpvplabel, imgp); 803 } 804 #endif 805 } else { 806 if (oldcred->cr_uid == oldcred->cr_ruid && 807 oldcred->cr_gid == oldcred->cr_rgid) 808 p->p_flag &= ~P_SUGID; 809 } 810 /* 811 * Set the new credentials. 812 */ 813 if (imgp->newcred != NULL) { 814 proc_set_cred(p, imgp->newcred); 815 crfree(oldcred); 816 oldcred = NULL; 817 } 818 819 /* 820 * Store the vp for use in procfs. This vnode was referenced by namei 821 * or fgetvp_exec. 822 */ 823 oldtextvp = p->p_textvp; 824 p->p_textvp = newtextvp; 825 826 #ifdef KDTRACE_HOOKS 827 /* 828 * Tell the DTrace fasttrap provider about the exec if it 829 * has declared an interest. 830 */ 831 if (dtrace_fasttrap_exec) 832 dtrace_fasttrap_exec(p); 833 #endif 834 835 /* 836 * Notify others that we exec'd, and clear the P_INEXEC flag 837 * as we're now a bona fide freshly-execed process. 838 */ 839 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 840 p->p_flag &= ~P_INEXEC; 841 842 /* clear "fork but no exec" flag, as we _are_ execing */ 843 p->p_acflag &= ~AFORK; 844 845 /* 846 * Free any previous argument cache and replace it with 847 * the new argument cache, if any. 848 */ 849 oldargs = p->p_args; 850 p->p_args = newargs; 851 newargs = NULL; 852 853 PROC_UNLOCK(p); 854 855 #ifdef HWPMC_HOOKS 856 /* 857 * Check if system-wide sampling is in effect or if the 858 * current process is using PMCs. If so, do exec() time 859 * processing. This processing needs to happen AFTER the 860 * P_INEXEC flag is cleared. 861 */ 862 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 863 VOP_UNLOCK(imgp->vp); 864 pe.pm_credentialschanged = credential_changing; 865 pe.pm_entryaddr = imgp->entry_addr; 866 867 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 868 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 869 } 870 #endif 871 872 /* Set values passed into the program in registers. */ 873 (*p->p_sysent->sv_setregs)(td, imgp, stack_base); 874 875 VOP_MMAPPED(imgp->vp); 876 877 SDT_PROBE1(proc, , , exec__success, args->fname); 878 879 exec_fail_dealloc: 880 if (error != 0) { 881 p->p_osrel = orig_osrel; 882 p->p_fctl0 = orig_fctl0; 883 } 884 885 if (imgp->firstpage != NULL) 886 exec_unmap_first_page(imgp); 887 888 if (imgp->vp != NULL) { 889 if (args->fname) 890 NDFREE(&nd, NDF_ONLY_PNBUF); 891 if (imgp->opened) 892 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 893 if (imgp->textset) 894 VOP_UNSET_TEXT_CHECKED(imgp->vp); 895 if (error != 0) 896 vput(imgp->vp); 897 else 898 VOP_UNLOCK(imgp->vp); 899 } 900 901 if (imgp->object != NULL) 902 vm_object_deallocate(imgp->object); 903 904 free(imgp->freepath, M_TEMP); 905 906 if (error == 0) { 907 if (p->p_ptevents & PTRACE_EXEC) { 908 PROC_LOCK(p); 909 if (p->p_ptevents & PTRACE_EXEC) 910 td->td_dbgflags |= TDB_EXEC; 911 PROC_UNLOCK(p); 912 } 913 } else { 914 exec_fail: 915 /* we're done here, clear P_INEXEC */ 916 PROC_LOCK(p); 917 p->p_flag &= ~P_INEXEC; 918 PROC_UNLOCK(p); 919 920 SDT_PROBE1(proc, , , exec__failure, error); 921 } 922 923 if (imgp->newcred != NULL && oldcred != NULL) 924 crfree(imgp->newcred); 925 926 #ifdef MAC 927 mac_execve_exit(imgp); 928 mac_execve_interpreter_exit(interpvplabel); 929 #endif 930 exec_free_args(args); 931 932 /* 933 * Handle deferred decrement of ref counts. 934 */ 935 if (oldtextvp != NULL) 936 vrele(oldtextvp); 937 #ifdef KTRACE 938 if (tracevp != NULL) 939 vrele(tracevp); 940 if (tracecred != NULL) 941 crfree(tracecred); 942 #endif 943 pargs_drop(oldargs); 944 pargs_drop(newargs); 945 if (oldsigacts != NULL) 946 sigacts_free(oldsigacts); 947 if (euip != NULL) 948 uifree(euip); 949 950 if (error && imgp->vmspace_destroyed) { 951 /* sorry, no more process anymore. exit gracefully */ 952 exec_cleanup(td, oldvmspace); 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 void 972 exec_cleanup(struct thread *td, struct vmspace *oldvmspace) 973 { 974 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 975 KASSERT(td->td_proc->p_vmspace != oldvmspace, 976 ("oldvmspace still used")); 977 vmspace_free(oldvmspace); 978 td->td_pflags &= ~TDP_EXECVMSPC; 979 } 980 } 981 982 int 983 exec_map_first_page(struct image_params *imgp) 984 { 985 vm_object_t object; 986 vm_page_t m; 987 int error; 988 989 if (imgp->firstpage != NULL) 990 exec_unmap_first_page(imgp); 991 992 object = imgp->vp->v_object; 993 if (object == NULL) 994 return (EACCES); 995 #if VM_NRESERVLEVEL > 0 996 if ((object->flags & OBJ_COLORED) == 0) { 997 VM_OBJECT_WLOCK(object); 998 vm_object_color(object, 0); 999 VM_OBJECT_WUNLOCK(object); 1000 } 1001 #endif 1002 error = vm_page_grab_valid_unlocked(&m, object, 0, 1003 VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) | 1004 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED); 1005 1006 if (error != VM_PAGER_OK) 1007 return (EIO); 1008 imgp->firstpage = sf_buf_alloc(m, 0); 1009 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1010 1011 return (0); 1012 } 1013 1014 void 1015 exec_unmap_first_page(struct image_params *imgp) 1016 { 1017 vm_page_t m; 1018 1019 if (imgp->firstpage != NULL) { 1020 m = sf_buf_page(imgp->firstpage); 1021 sf_buf_free(imgp->firstpage); 1022 imgp->firstpage = NULL; 1023 vm_page_unwire(m, PQ_ACTIVE); 1024 } 1025 } 1026 1027 /* 1028 * Destroy old address space, and allocate a new stack. 1029 * The new stack is only sgrowsiz large because it is grown 1030 * automatically on a page fault. 1031 */ 1032 int 1033 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1034 { 1035 int error; 1036 struct proc *p = imgp->proc; 1037 struct vmspace *vmspace = p->p_vmspace; 1038 struct thread *td = curthread; 1039 vm_object_t obj; 1040 struct rlimit rlim_stack; 1041 vm_offset_t sv_minuser, stack_addr; 1042 vm_map_t map; 1043 u_long ssiz; 1044 1045 imgp->vmspace_destroyed = 1; 1046 imgp->sysent = sv; 1047 1048 sigfastblock_clear(td); 1049 1050 /* May be called with Giant held */ 1051 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1052 1053 /* 1054 * Blow away entire process VM, if address space not shared, 1055 * otherwise, create a new VM space so that other threads are 1056 * not disrupted 1057 */ 1058 map = &vmspace->vm_map; 1059 if (map_at_zero) 1060 sv_minuser = sv->sv_minuser; 1061 else 1062 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1063 if (refcount_load(&vmspace->vm_refcnt) == 1 && 1064 vm_map_min(map) == sv_minuser && 1065 vm_map_max(map) == sv->sv_maxuser && 1066 cpu_exec_vmspace_reuse(p, map)) { 1067 shmexit(vmspace); 1068 pmap_remove_pages(vmspace_pmap(vmspace)); 1069 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1070 /* 1071 * An exec terminates mlockall(MCL_FUTURE), ASLR state 1072 * must be re-evaluated. 1073 */ 1074 vm_map_lock(map); 1075 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1076 MAP_ASLR_IGNSTART); 1077 vm_map_unlock(map); 1078 } else { 1079 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1080 if (error) 1081 return (error); 1082 vmspace = p->p_vmspace; 1083 map = &vmspace->vm_map; 1084 } 1085 map->flags |= imgp->map_flags; 1086 1087 /* Map a shared page */ 1088 obj = sv->sv_shared_page_obj; 1089 if (obj != NULL) { 1090 vm_object_reference(obj); 1091 error = vm_map_fixed(map, obj, 0, 1092 sv->sv_shared_page_base, sv->sv_shared_page_len, 1093 VM_PROT_READ | VM_PROT_EXECUTE, 1094 VM_PROT_READ | VM_PROT_EXECUTE, 1095 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1096 if (error != KERN_SUCCESS) { 1097 vm_object_deallocate(obj); 1098 return (vm_mmap_to_errno(error)); 1099 } 1100 } 1101 1102 /* Allocate a new stack */ 1103 if (imgp->stack_sz != 0) { 1104 ssiz = trunc_page(imgp->stack_sz); 1105 PROC_LOCK(p); 1106 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1107 PROC_UNLOCK(p); 1108 if (ssiz > rlim_stack.rlim_max) 1109 ssiz = rlim_stack.rlim_max; 1110 if (ssiz > rlim_stack.rlim_cur) { 1111 rlim_stack.rlim_cur = ssiz; 1112 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1113 } 1114 } else if (sv->sv_maxssiz != NULL) { 1115 ssiz = *sv->sv_maxssiz; 1116 } else { 1117 ssiz = maxssiz; 1118 } 1119 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1120 if (ssiz < imgp->eff_stack_sz) 1121 imgp->eff_stack_sz = ssiz; 1122 stack_addr = sv->sv_usrstack - ssiz; 1123 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, 1124 obj != NULL && imgp->stack_prot != 0 ? imgp->stack_prot : 1125 sv->sv_stackprot, VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1126 if (error != KERN_SUCCESS) 1127 return (vm_mmap_to_errno(error)); 1128 1129 /* 1130 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1131 * are still used to enforce the stack rlimit on the process stack. 1132 */ 1133 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1134 vmspace->vm_maxsaddr = (char *)stack_addr; 1135 1136 return (0); 1137 } 1138 1139 /* 1140 * Copy out argument and environment strings from the old process address 1141 * space into the temporary string buffer. 1142 */ 1143 int 1144 exec_copyin_args(struct image_args *args, const char *fname, 1145 enum uio_seg segflg, char **argv, char **envv) 1146 { 1147 u_long arg, env; 1148 int error; 1149 1150 bzero(args, sizeof(*args)); 1151 if (argv == NULL) 1152 return (EFAULT); 1153 1154 /* 1155 * Allocate demand-paged memory for the file name, argument, and 1156 * environment strings. 1157 */ 1158 error = exec_alloc_args(args); 1159 if (error != 0) 1160 return (error); 1161 1162 /* 1163 * Copy the file name. 1164 */ 1165 error = exec_args_add_fname(args, fname, segflg); 1166 if (error != 0) 1167 goto err_exit; 1168 1169 /* 1170 * extract arguments first 1171 */ 1172 for (;;) { 1173 error = fueword(argv++, &arg); 1174 if (error == -1) { 1175 error = EFAULT; 1176 goto err_exit; 1177 } 1178 if (arg == 0) 1179 break; 1180 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1181 UIO_USERSPACE); 1182 if (error != 0) 1183 goto err_exit; 1184 } 1185 1186 /* 1187 * extract environment strings 1188 */ 1189 if (envv) { 1190 for (;;) { 1191 error = fueword(envv++, &env); 1192 if (error == -1) { 1193 error = EFAULT; 1194 goto err_exit; 1195 } 1196 if (env == 0) 1197 break; 1198 error = exec_args_add_env(args, 1199 (char *)(uintptr_t)env, UIO_USERSPACE); 1200 if (error != 0) 1201 goto err_exit; 1202 } 1203 } 1204 1205 return (0); 1206 1207 err_exit: 1208 exec_free_args(args); 1209 return (error); 1210 } 1211 1212 int 1213 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1214 const void *data, size_t datalen, const int *fds, size_t fdslen) 1215 { 1216 struct filedesc *ofdp; 1217 const char *p; 1218 int *kfds; 1219 int error; 1220 1221 memset(args, '\0', sizeof(*args)); 1222 ofdp = td->td_proc->p_fd; 1223 if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles) 1224 return (E2BIG); 1225 error = exec_alloc_args(args); 1226 if (error != 0) 1227 return (error); 1228 1229 args->begin_argv = args->buf; 1230 args->stringspace = ARG_MAX; 1231 1232 if (datalen > 0) { 1233 /* 1234 * Argument buffer has been provided. Copy it into the 1235 * kernel as a single string and add a terminating null 1236 * byte. 1237 */ 1238 error = copyin(data, args->begin_argv, datalen); 1239 if (error != 0) 1240 goto err_exit; 1241 args->begin_argv[datalen] = '\0'; 1242 args->endp = args->begin_argv + datalen + 1; 1243 args->stringspace -= datalen + 1; 1244 1245 /* 1246 * Traditional argument counting. Count the number of 1247 * null bytes. 1248 */ 1249 for (p = args->begin_argv; p < args->endp; ++p) 1250 if (*p == '\0') 1251 ++args->argc; 1252 } else { 1253 /* No argument buffer provided. */ 1254 args->endp = args->begin_argv; 1255 } 1256 1257 /* Create new file descriptor table. */ 1258 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1259 error = copyin(fds, kfds, fdslen * sizeof(int)); 1260 if (error != 0) { 1261 free(kfds, M_TEMP); 1262 goto err_exit; 1263 } 1264 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1265 free(kfds, M_TEMP); 1266 if (error != 0) 1267 goto err_exit; 1268 1269 return (0); 1270 err_exit: 1271 exec_free_args(args); 1272 return (error); 1273 } 1274 1275 struct exec_args_kva { 1276 vm_offset_t addr; 1277 u_int gen; 1278 SLIST_ENTRY(exec_args_kva) next; 1279 }; 1280 1281 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1282 1283 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1284 static struct mtx exec_args_kva_mtx; 1285 static u_int exec_args_gen; 1286 1287 static void 1288 exec_prealloc_args_kva(void *arg __unused) 1289 { 1290 struct exec_args_kva *argkva; 1291 u_int i; 1292 1293 SLIST_INIT(&exec_args_kva_freelist); 1294 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1295 for (i = 0; i < exec_map_entries; i++) { 1296 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1297 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1298 argkva->gen = exec_args_gen; 1299 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1300 } 1301 } 1302 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1303 1304 static vm_offset_t 1305 exec_alloc_args_kva(void **cookie) 1306 { 1307 struct exec_args_kva *argkva; 1308 1309 argkva = (void *)atomic_readandclear_ptr( 1310 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1311 if (argkva == NULL) { 1312 mtx_lock(&exec_args_kva_mtx); 1313 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1314 (void)mtx_sleep(&exec_args_kva_freelist, 1315 &exec_args_kva_mtx, 0, "execkva", 0); 1316 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1317 mtx_unlock(&exec_args_kva_mtx); 1318 } 1319 *(struct exec_args_kva **)cookie = argkva; 1320 return (argkva->addr); 1321 } 1322 1323 static void 1324 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1325 { 1326 vm_offset_t base; 1327 1328 base = argkva->addr; 1329 if (argkva->gen != gen) { 1330 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1331 MADV_FREE); 1332 argkva->gen = gen; 1333 } 1334 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1335 (uintptr_t)NULL, (uintptr_t)argkva)) { 1336 mtx_lock(&exec_args_kva_mtx); 1337 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1338 wakeup_one(&exec_args_kva_freelist); 1339 mtx_unlock(&exec_args_kva_mtx); 1340 } 1341 } 1342 1343 static void 1344 exec_free_args_kva(void *cookie) 1345 { 1346 1347 exec_release_args_kva(cookie, exec_args_gen); 1348 } 1349 1350 static void 1351 exec_args_kva_lowmem(void *arg __unused) 1352 { 1353 SLIST_HEAD(, exec_args_kva) head; 1354 struct exec_args_kva *argkva; 1355 u_int gen; 1356 int i; 1357 1358 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1359 1360 /* 1361 * Force an madvise of each KVA range. Any currently allocated ranges 1362 * will have MADV_FREE applied once they are freed. 1363 */ 1364 SLIST_INIT(&head); 1365 mtx_lock(&exec_args_kva_mtx); 1366 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1367 mtx_unlock(&exec_args_kva_mtx); 1368 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1369 SLIST_REMOVE_HEAD(&head, next); 1370 exec_release_args_kva(argkva, gen); 1371 } 1372 1373 CPU_FOREACH(i) { 1374 argkva = (void *)atomic_readandclear_ptr( 1375 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1376 if (argkva != NULL) 1377 exec_release_args_kva(argkva, gen); 1378 } 1379 } 1380 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1381 EVENTHANDLER_PRI_ANY); 1382 1383 /* 1384 * Allocate temporary demand-paged, zero-filled memory for the file name, 1385 * argument, and environment strings. 1386 */ 1387 int 1388 exec_alloc_args(struct image_args *args) 1389 { 1390 1391 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1392 return (0); 1393 } 1394 1395 void 1396 exec_free_args(struct image_args *args) 1397 { 1398 1399 if (args->buf != NULL) { 1400 exec_free_args_kva(args->bufkva); 1401 args->buf = NULL; 1402 } 1403 if (args->fname_buf != NULL) { 1404 free(args->fname_buf, M_TEMP); 1405 args->fname_buf = NULL; 1406 } 1407 if (args->fdp != NULL) 1408 fdescfree_remapped(args->fdp); 1409 } 1410 1411 /* 1412 * A set to functions to fill struct image args. 1413 * 1414 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1415 * fname) before the other functions. All exec_args_add_arg() calls must 1416 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1417 * may be called any time after exec_args_add_fname(). 1418 * 1419 * exec_args_add_fname() - install path to be executed 1420 * exec_args_add_arg() - append an argument string 1421 * exec_args_add_env() - append an env string 1422 * exec_args_adjust_args() - adjust location of the argument list to 1423 * allow new arguments to be prepended 1424 */ 1425 int 1426 exec_args_add_fname(struct image_args *args, const char *fname, 1427 enum uio_seg segflg) 1428 { 1429 int error; 1430 size_t length; 1431 1432 KASSERT(args->fname == NULL, ("fname already appended")); 1433 KASSERT(args->endp == NULL, ("already appending to args")); 1434 1435 if (fname != NULL) { 1436 args->fname = args->buf; 1437 error = segflg == UIO_SYSSPACE ? 1438 copystr(fname, args->fname, PATH_MAX, &length) : 1439 copyinstr(fname, args->fname, PATH_MAX, &length); 1440 if (error != 0) 1441 return (error == ENAMETOOLONG ? E2BIG : error); 1442 } else 1443 length = 0; 1444 1445 /* Set up for _arg_*()/_env_*() */ 1446 args->endp = args->buf + length; 1447 /* begin_argv must be set and kept updated */ 1448 args->begin_argv = args->endp; 1449 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1450 ("too little space remaining for arguments %zu < %zu", 1451 exec_map_entry_size - length, (size_t)ARG_MAX)); 1452 args->stringspace = ARG_MAX; 1453 1454 return (0); 1455 } 1456 1457 static int 1458 exec_args_add_str(struct image_args *args, const char *str, 1459 enum uio_seg segflg, int *countp) 1460 { 1461 int error; 1462 size_t length; 1463 1464 KASSERT(args->endp != NULL, ("endp not initialized")); 1465 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1466 1467 error = (segflg == UIO_SYSSPACE) ? 1468 copystr(str, args->endp, args->stringspace, &length) : 1469 copyinstr(str, args->endp, args->stringspace, &length); 1470 if (error != 0) 1471 return (error == ENAMETOOLONG ? E2BIG : error); 1472 args->stringspace -= length; 1473 args->endp += length; 1474 (*countp)++; 1475 1476 return (0); 1477 } 1478 1479 int 1480 exec_args_add_arg(struct image_args *args, const char *argp, 1481 enum uio_seg segflg) 1482 { 1483 1484 KASSERT(args->envc == 0, ("appending args after env")); 1485 1486 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1487 } 1488 1489 int 1490 exec_args_add_env(struct image_args *args, const char *envp, 1491 enum uio_seg segflg) 1492 { 1493 1494 if (args->envc == 0) 1495 args->begin_envv = args->endp; 1496 1497 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1498 } 1499 1500 int 1501 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1502 { 1503 ssize_t offset; 1504 1505 KASSERT(args->endp != NULL, ("endp not initialized")); 1506 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1507 1508 offset = extend - consume; 1509 if (args->stringspace < offset) 1510 return (E2BIG); 1511 memmove(args->begin_argv + extend, args->begin_argv + consume, 1512 args->endp - args->begin_argv + consume); 1513 if (args->envc > 0) 1514 args->begin_envv += offset; 1515 args->endp += offset; 1516 args->stringspace -= offset; 1517 return (0); 1518 } 1519 1520 char * 1521 exec_args_get_begin_envv(struct image_args *args) 1522 { 1523 1524 KASSERT(args->endp != NULL, ("endp not initialized")); 1525 1526 if (args->envc > 0) 1527 return (args->begin_envv); 1528 return (args->endp); 1529 } 1530 1531 /* 1532 * Copy strings out to the new process address space, constructing new arg 1533 * and env vector tables. Return a pointer to the base so that it can be used 1534 * as the initial stack pointer. 1535 */ 1536 int 1537 exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base) 1538 { 1539 int argc, envc; 1540 char **vectp; 1541 char *stringp; 1542 uintptr_t destp, ustringp; 1543 struct ps_strings *arginfo; 1544 struct proc *p; 1545 size_t execpath_len; 1546 int error, szsigcode, szps; 1547 char canary[sizeof(long) * 8]; 1548 1549 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1550 /* 1551 * Calculate string base and vector table pointers. 1552 * Also deal with signal trampoline code for this exec type. 1553 */ 1554 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1555 execpath_len = strlen(imgp->execpath) + 1; 1556 else 1557 execpath_len = 0; 1558 p = imgp->proc; 1559 szsigcode = 0; 1560 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1561 imgp->ps_strings = arginfo; 1562 if (p->p_sysent->sv_sigcode_base == 0) { 1563 if (p->p_sysent->sv_szsigcode != NULL) 1564 szsigcode = *(p->p_sysent->sv_szsigcode); 1565 } 1566 destp = (uintptr_t)arginfo; 1567 1568 /* 1569 * install sigcode 1570 */ 1571 if (szsigcode != 0) { 1572 destp -= szsigcode; 1573 destp = rounddown2(destp, sizeof(void *)); 1574 error = copyout(p->p_sysent->sv_sigcode, (void *)destp, 1575 szsigcode); 1576 if (error != 0) 1577 return (error); 1578 } 1579 1580 /* 1581 * Copy the image path for the rtld. 1582 */ 1583 if (execpath_len != 0) { 1584 destp -= execpath_len; 1585 destp = rounddown2(destp, sizeof(void *)); 1586 imgp->execpathp = (void *)destp; 1587 error = copyout(imgp->execpath, imgp->execpathp, execpath_len); 1588 if (error != 0) 1589 return (error); 1590 } 1591 1592 /* 1593 * Prepare the canary for SSP. 1594 */ 1595 arc4rand(canary, sizeof(canary), 0); 1596 destp -= sizeof(canary); 1597 imgp->canary = (void *)destp; 1598 error = copyout(canary, imgp->canary, sizeof(canary)); 1599 if (error != 0) 1600 return (error); 1601 imgp->canarylen = sizeof(canary); 1602 1603 /* 1604 * Prepare the pagesizes array. 1605 */ 1606 destp -= szps; 1607 destp = rounddown2(destp, sizeof(void *)); 1608 imgp->pagesizes = (void *)destp; 1609 error = copyout(pagesizes, imgp->pagesizes, szps); 1610 if (error != 0) 1611 return (error); 1612 imgp->pagesizeslen = szps; 1613 1614 /* 1615 * Allocate room for the argument and environment strings. 1616 */ 1617 destp -= ARG_MAX - imgp->args->stringspace; 1618 destp = rounddown2(destp, sizeof(void *)); 1619 ustringp = destp; 1620 1621 if (imgp->sysent->sv_stackgap != NULL) 1622 imgp->sysent->sv_stackgap(imgp, &destp); 1623 1624 if (imgp->auxargs) { 1625 /* 1626 * Allocate room on the stack for the ELF auxargs 1627 * array. It has up to AT_COUNT entries. 1628 */ 1629 destp -= AT_COUNT * sizeof(Elf_Auxinfo); 1630 destp = rounddown2(destp, sizeof(void *)); 1631 } 1632 1633 vectp = (char **)destp; 1634 1635 /* 1636 * Allocate room for the argv[] and env vectors including the 1637 * terminating NULL pointers. 1638 */ 1639 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1640 1641 /* 1642 * vectp also becomes our initial stack base 1643 */ 1644 *stack_base = (uintptr_t)vectp; 1645 1646 stringp = imgp->args->begin_argv; 1647 argc = imgp->args->argc; 1648 envc = imgp->args->envc; 1649 1650 /* 1651 * Copy out strings - arguments and environment. 1652 */ 1653 error = copyout(stringp, (void *)ustringp, 1654 ARG_MAX - imgp->args->stringspace); 1655 if (error != 0) 1656 return (error); 1657 1658 /* 1659 * Fill in "ps_strings" struct for ps, w, etc. 1660 */ 1661 imgp->argv = vectp; 1662 if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 || 1663 suword32(&arginfo->ps_nargvstr, argc) != 0) 1664 return (EFAULT); 1665 1666 /* 1667 * Fill in argument portion of vector table. 1668 */ 1669 for (; argc > 0; --argc) { 1670 if (suword(vectp++, ustringp) != 0) 1671 return (EFAULT); 1672 while (*stringp++ != 0) 1673 ustringp++; 1674 ustringp++; 1675 } 1676 1677 /* a null vector table pointer separates the argp's from the envp's */ 1678 if (suword(vectp++, 0) != 0) 1679 return (EFAULT); 1680 1681 imgp->envv = vectp; 1682 if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 || 1683 suword32(&arginfo->ps_nenvstr, envc) != 0) 1684 return (EFAULT); 1685 1686 /* 1687 * Fill in environment portion of vector table. 1688 */ 1689 for (; envc > 0; --envc) { 1690 if (suword(vectp++, ustringp) != 0) 1691 return (EFAULT); 1692 while (*stringp++ != 0) 1693 ustringp++; 1694 ustringp++; 1695 } 1696 1697 /* end of vector table is a null pointer */ 1698 if (suword(vectp, 0) != 0) 1699 return (EFAULT); 1700 1701 if (imgp->auxargs) { 1702 vectp++; 1703 error = imgp->sysent->sv_copyout_auxargs(imgp, 1704 (uintptr_t)vectp); 1705 if (error != 0) 1706 return (error); 1707 } 1708 1709 return (0); 1710 } 1711 1712 /* 1713 * Check permissions of file to execute. 1714 * Called with imgp->vp locked. 1715 * Return 0 for success or error code on failure. 1716 */ 1717 int 1718 exec_check_permissions(struct image_params *imgp) 1719 { 1720 struct vnode *vp = imgp->vp; 1721 struct vattr *attr = imgp->attr; 1722 struct thread *td; 1723 int error; 1724 1725 td = curthread; 1726 1727 /* Get file attributes */ 1728 error = VOP_GETATTR(vp, attr, td->td_ucred); 1729 if (error) 1730 return (error); 1731 1732 #ifdef MAC 1733 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1734 if (error) 1735 return (error); 1736 #endif 1737 1738 /* 1739 * 1) Check if file execution is disabled for the filesystem that 1740 * this file resides on. 1741 * 2) Ensure that at least one execute bit is on. Otherwise, a 1742 * privileged user will always succeed, and we don't want this 1743 * to happen unless the file really is executable. 1744 * 3) Ensure that the file is a regular file. 1745 */ 1746 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1747 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1748 (attr->va_type != VREG)) 1749 return (EACCES); 1750 1751 /* 1752 * Zero length files can't be exec'd 1753 */ 1754 if (attr->va_size == 0) 1755 return (ENOEXEC); 1756 1757 /* 1758 * Check for execute permission to file based on current credentials. 1759 */ 1760 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1761 if (error) 1762 return (error); 1763 1764 /* 1765 * Check number of open-for-writes on the file and deny execution 1766 * if there are any. 1767 * 1768 * Add a text reference now so no one can write to the 1769 * executable while we're activating it. 1770 * 1771 * Remember if this was set before and unset it in case this is not 1772 * actually an executable image. 1773 */ 1774 error = VOP_SET_TEXT(vp); 1775 if (error != 0) 1776 return (error); 1777 imgp->textset = true; 1778 1779 /* 1780 * Call filesystem specific open routine (which does nothing in the 1781 * general case). 1782 */ 1783 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1784 if (error == 0) 1785 imgp->opened = 1; 1786 return (error); 1787 } 1788 1789 /* 1790 * Exec handler registration 1791 */ 1792 int 1793 exec_register(const struct execsw *execsw_arg) 1794 { 1795 const struct execsw **es, **xs, **newexecsw; 1796 u_int count = 2; /* New slot and trailing NULL */ 1797 1798 if (execsw) 1799 for (es = execsw; *es; es++) 1800 count++; 1801 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1802 xs = newexecsw; 1803 if (execsw) 1804 for (es = execsw; *es; es++) 1805 *xs++ = *es; 1806 *xs++ = execsw_arg; 1807 *xs = NULL; 1808 if (execsw) 1809 free(execsw, M_TEMP); 1810 execsw = newexecsw; 1811 return (0); 1812 } 1813 1814 int 1815 exec_unregister(const struct execsw *execsw_arg) 1816 { 1817 const struct execsw **es, **xs, **newexecsw; 1818 int count = 1; 1819 1820 if (execsw == NULL) 1821 panic("unregister with no handlers left?\n"); 1822 1823 for (es = execsw; *es; es++) { 1824 if (*es == execsw_arg) 1825 break; 1826 } 1827 if (*es == NULL) 1828 return (ENOENT); 1829 for (es = execsw; *es; es++) 1830 if (*es != execsw_arg) 1831 count++; 1832 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1833 xs = newexecsw; 1834 for (es = execsw; *es; es++) 1835 if (*es != execsw_arg) 1836 *xs++ = *es; 1837 *xs = NULL; 1838 if (execsw) 1839 free(execsw, M_TEMP); 1840 execsw = newexecsw; 1841 return (0); 1842 } 1843