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 * 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/timers.h> 71 #include <sys/umtx.h> 72 #include <sys/vnode.h> 73 #include <sys/wait.h> 74 #ifdef KTRACE 75 #include <sys/ktrace.h> 76 #endif 77 78 #include <vm/vm.h> 79 #include <vm/vm_param.h> 80 #include <vm/pmap.h> 81 #include <vm/vm_page.h> 82 #include <vm/vm_map.h> 83 #include <vm/vm_kern.h> 84 #include <vm/vm_extern.h> 85 #include <vm/vm_object.h> 86 #include <vm/vm_pager.h> 87 88 #ifdef HWPMC_HOOKS 89 #include <sys/pmckern.h> 90 #endif 91 92 #include <machine/reg.h> 93 94 #include <security/audit/audit.h> 95 #include <security/mac/mac_framework.h> 96 97 #ifdef KDTRACE_HOOKS 98 #include <sys/dtrace_bsd.h> 99 dtrace_execexit_func_t dtrace_fasttrap_exec; 100 #endif 101 102 SDT_PROVIDER_DECLARE(proc); 103 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 104 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 105 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 106 107 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 108 109 int coredump_pack_fileinfo = 1; 110 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 111 &coredump_pack_fileinfo, 0, 112 "Enable file path packing in 'procstat -f' coredump notes"); 113 114 int coredump_pack_vmmapinfo = 1; 115 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 116 &coredump_pack_vmmapinfo, 0, 117 "Enable file path packing in 'procstat -v' coredump notes"); 118 119 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 120 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 121 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 122 static int do_execve(struct thread *td, struct image_args *args, 123 struct mac *mac_p, struct vmspace *oldvmspace); 124 125 /* XXX This should be vm_size_t. */ 126 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 127 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", 128 "Location of process' ps_strings structure"); 129 130 /* XXX This should be vm_size_t. */ 131 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 132 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", 133 "Top of process stack"); 134 135 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 136 NULL, 0, sysctl_kern_stackprot, "I", 137 "Stack memory permissions"); 138 139 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 140 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 141 &ps_arg_cache_limit, 0, 142 "Process' command line characters cache limit"); 143 144 static int disallow_high_osrel; 145 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 146 &disallow_high_osrel, 0, 147 "Disallow execution of binaries built for higher version of the world"); 148 149 static int map_at_zero = 0; 150 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 151 "Permit processes to map an object at virtual address 0."); 152 153 static int 154 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 155 { 156 struct proc *p; 157 int error; 158 159 p = curproc; 160 #ifdef SCTL_MASK32 161 if (req->flags & SCTL_MASK32) { 162 unsigned int val; 163 val = (unsigned int)p->p_sysent->sv_psstrings; 164 error = SYSCTL_OUT(req, &val, sizeof(val)); 165 } else 166 #endif 167 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 168 sizeof(p->p_sysent->sv_psstrings)); 169 return error; 170 } 171 172 static int 173 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 174 { 175 struct proc *p; 176 int error; 177 178 p = curproc; 179 #ifdef SCTL_MASK32 180 if (req->flags & SCTL_MASK32) { 181 unsigned int val; 182 val = (unsigned int)p->p_sysent->sv_usrstack; 183 error = SYSCTL_OUT(req, &val, sizeof(val)); 184 } else 185 #endif 186 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 187 sizeof(p->p_sysent->sv_usrstack)); 188 return error; 189 } 190 191 static int 192 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 193 { 194 struct proc *p; 195 196 p = curproc; 197 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 198 sizeof(p->p_sysent->sv_stackprot))); 199 } 200 201 /* 202 * Each of the items is a pointer to a `const struct execsw', hence the 203 * double pointer here. 204 */ 205 static const struct execsw **execsw; 206 207 #ifndef _SYS_SYSPROTO_H_ 208 struct execve_args { 209 char *fname; 210 char **argv; 211 char **envv; 212 }; 213 #endif 214 215 int 216 sys_execve(struct thread *td, struct execve_args *uap) 217 { 218 struct image_args args; 219 struct vmspace *oldvmspace; 220 int error; 221 222 error = pre_execve(td, &oldvmspace); 223 if (error != 0) 224 return (error); 225 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 226 uap->argv, uap->envv); 227 if (error == 0) 228 error = kern_execve(td, &args, NULL, oldvmspace); 229 post_execve(td, error, oldvmspace); 230 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 231 return (error); 232 } 233 234 #ifndef _SYS_SYSPROTO_H_ 235 struct fexecve_args { 236 int fd; 237 char **argv; 238 char **envv; 239 }; 240 #endif 241 int 242 sys_fexecve(struct thread *td, struct fexecve_args *uap) 243 { 244 struct image_args args; 245 struct vmspace *oldvmspace; 246 int error; 247 248 error = pre_execve(td, &oldvmspace); 249 if (error != 0) 250 return (error); 251 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 252 uap->argv, uap->envv); 253 if (error == 0) { 254 args.fd = uap->fd; 255 error = kern_execve(td, &args, NULL, oldvmspace); 256 } 257 post_execve(td, error, oldvmspace); 258 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 259 return (error); 260 } 261 262 #ifndef _SYS_SYSPROTO_H_ 263 struct __mac_execve_args { 264 char *fname; 265 char **argv; 266 char **envv; 267 struct mac *mac_p; 268 }; 269 #endif 270 271 int 272 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 273 { 274 #ifdef MAC 275 struct image_args args; 276 struct vmspace *oldvmspace; 277 int error; 278 279 error = pre_execve(td, &oldvmspace); 280 if (error != 0) 281 return (error); 282 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 283 uap->argv, uap->envv); 284 if (error == 0) 285 error = kern_execve(td, &args, uap->mac_p, oldvmspace); 286 post_execve(td, error, oldvmspace); 287 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 288 return (error); 289 #else 290 return (ENOSYS); 291 #endif 292 } 293 294 int 295 pre_execve(struct thread *td, struct vmspace **oldvmspace) 296 { 297 struct proc *p; 298 int error; 299 300 KASSERT(td == curthread, ("non-current thread %p", td)); 301 error = 0; 302 p = td->td_proc; 303 if ((p->p_flag & P_HADTHREADS) != 0) { 304 PROC_LOCK(p); 305 if (thread_single(p, SINGLE_BOUNDARY) != 0) 306 error = ERESTART; 307 PROC_UNLOCK(p); 308 } 309 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 310 ("nested execve")); 311 *oldvmspace = p->p_vmspace; 312 return (error); 313 } 314 315 void 316 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 317 { 318 struct proc *p; 319 320 KASSERT(td == curthread, ("non-current thread %p", td)); 321 p = td->td_proc; 322 if ((p->p_flag & P_HADTHREADS) != 0) { 323 PROC_LOCK(p); 324 /* 325 * If success, we upgrade to SINGLE_EXIT state to 326 * force other threads to suicide. 327 */ 328 if (error == EJUSTRETURN) 329 thread_single(p, SINGLE_EXIT); 330 else 331 thread_single_end(p, SINGLE_BOUNDARY); 332 PROC_UNLOCK(p); 333 } 334 exec_cleanup(td, oldvmspace); 335 } 336 337 /* 338 * kern_execve() has the astonishing property of not always returning to 339 * the caller. If sufficiently bad things happen during the call to 340 * do_execve(), it can end up calling exit1(); as a result, callers must 341 * avoid doing anything which they might need to undo (e.g., allocating 342 * memory). 343 */ 344 int 345 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 346 struct vmspace *oldvmspace) 347 { 348 349 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 350 exec_args_get_begin_envv(args) - args->begin_argv); 351 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc, 352 args->endp - exec_args_get_begin_envv(args)); 353 return (do_execve(td, args, mac_p, oldvmspace)); 354 } 355 356 /* 357 * In-kernel implementation of execve(). All arguments are assumed to be 358 * userspace pointers from the passed thread. 359 */ 360 static int 361 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 362 struct vmspace *oldvmspace) 363 { 364 struct proc *p = td->td_proc; 365 struct nameidata nd; 366 struct ucred *oldcred; 367 struct uidinfo *euip = NULL; 368 uintptr_t stack_base; 369 struct image_params image_params, *imgp; 370 struct vattr attr; 371 int (*img_first)(struct image_params *); 372 struct pargs *oldargs = NULL, *newargs = NULL; 373 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 374 #ifdef KTRACE 375 struct vnode *tracevp = NULL; 376 struct ucred *tracecred = NULL; 377 #endif 378 struct vnode *oldtextvp = NULL, *newtextvp; 379 int credential_changing; 380 #ifdef MAC 381 struct label *interpvplabel = NULL; 382 int will_transition; 383 #endif 384 #ifdef HWPMC_HOOKS 385 struct pmckern_procexec pe; 386 #endif 387 int error, i, orig_osrel; 388 uint32_t orig_fctl0; 389 static const char fexecv_proc_title[] = "(fexecv)"; 390 391 imgp = &image_params; 392 393 /* 394 * Lock the process and set the P_INEXEC flag to indicate that 395 * it should be left alone until we're done here. This is 396 * necessary to avoid race conditions - e.g. in ptrace() - 397 * that might allow a local user to illicitly obtain elevated 398 * privileges. 399 */ 400 PROC_LOCK(p); 401 KASSERT((p->p_flag & P_INEXEC) == 0, 402 ("%s(): process already has P_INEXEC flag", __func__)); 403 p->p_flag |= P_INEXEC; 404 PROC_UNLOCK(p); 405 406 /* 407 * Initialize part of the common data 408 */ 409 bzero(imgp, sizeof(*imgp)); 410 imgp->proc = p; 411 imgp->attr = &attr; 412 imgp->args = args; 413 oldcred = p->p_ucred; 414 orig_osrel = p->p_osrel; 415 orig_fctl0 = p->p_fctl0; 416 417 #ifdef MAC 418 error = mac_execve_enter(imgp, mac_p); 419 if (error) 420 goto exec_fail; 421 #endif 422 423 /* 424 * Translate the file name. namei() returns a vnode pointer 425 * in ni_vp among other things. 426 * 427 * XXXAUDIT: It would be desirable to also audit the name of the 428 * interpreter if this is an interpreted binary. 429 */ 430 if (args->fname != NULL) { 431 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 432 SAVENAME | AUDITVNODE1, UIO_SYSSPACE, args->fname, td); 433 } 434 435 SDT_PROBE1(proc, , , exec, args->fname); 436 437 interpret: 438 if (args->fname != NULL) { 439 #ifdef CAPABILITY_MODE 440 /* 441 * While capability mode can't reach this point via direct 442 * path arguments to execve(), we also don't allow 443 * interpreters to be used in capability mode (for now). 444 * Catch indirect lookups and return a permissions error. 445 */ 446 if (IN_CAPABILITY_MODE(td)) { 447 error = ECAPMODE; 448 goto exec_fail; 449 } 450 #endif 451 error = namei(&nd); 452 if (error) 453 goto exec_fail; 454 455 newtextvp = nd.ni_vp; 456 imgp->vp = newtextvp; 457 } else { 458 AUDIT_ARG_FD(args->fd); 459 /* 460 * Descriptors opened only with O_EXEC or O_RDONLY are allowed. 461 */ 462 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, &newtextvp); 463 if (error) 464 goto exec_fail; 465 vn_lock(newtextvp, LK_SHARED | LK_RETRY); 466 AUDIT_ARG_VNODE1(newtextvp); 467 imgp->vp = newtextvp; 468 } 469 470 /* 471 * Check file permissions. Also 'opens' file and sets its vnode to 472 * text mode. 473 */ 474 error = exec_check_permissions(imgp); 475 if (error) 476 goto exec_fail_dealloc; 477 478 imgp->object = imgp->vp->v_object; 479 if (imgp->object != NULL) 480 vm_object_reference(imgp->object); 481 482 error = exec_map_first_page(imgp); 483 if (error) 484 goto exec_fail_dealloc; 485 486 imgp->proc->p_osrel = 0; 487 imgp->proc->p_fctl0 = 0; 488 489 /* 490 * Implement image setuid/setgid. 491 * 492 * Determine new credentials before attempting image activators 493 * so that it can be used by process_exec handlers to determine 494 * credential/setid changes. 495 * 496 * Don't honor setuid/setgid if the filesystem prohibits it or if 497 * the process is being traced. 498 * 499 * We disable setuid/setgid/etc in capability mode on the basis 500 * that most setugid applications are not written with that 501 * environment in mind, and will therefore almost certainly operate 502 * incorrectly. In principle there's no reason that setugid 503 * applications might not be useful in capability mode, so we may want 504 * to reconsider this conservative design choice in the future. 505 * 506 * XXXMAC: For the time being, use NOSUID to also prohibit 507 * transitions on the file system. 508 */ 509 credential_changing = 0; 510 credential_changing |= (attr.va_mode & S_ISUID) && 511 oldcred->cr_uid != attr.va_uid; 512 credential_changing |= (attr.va_mode & S_ISGID) && 513 oldcred->cr_gid != attr.va_gid; 514 #ifdef MAC 515 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 516 interpvplabel, imgp); 517 credential_changing |= will_transition; 518 #endif 519 520 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 521 if (credential_changing) 522 imgp->proc->p_pdeathsig = 0; 523 524 if (credential_changing && 525 #ifdef CAPABILITY_MODE 526 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 527 #endif 528 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 529 (p->p_flag & P_TRACED) == 0) { 530 imgp->credential_setid = true; 531 VOP_UNLOCK(imgp->vp); 532 imgp->newcred = crdup(oldcred); 533 if (attr.va_mode & S_ISUID) { 534 euip = uifind(attr.va_uid); 535 change_euid(imgp->newcred, euip); 536 } 537 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 538 if (attr.va_mode & S_ISGID) 539 change_egid(imgp->newcred, attr.va_gid); 540 /* 541 * Implement correct POSIX saved-id behavior. 542 * 543 * XXXMAC: Note that the current logic will save the 544 * uid and gid if a MAC domain transition occurs, even 545 * though maybe it shouldn't. 546 */ 547 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 548 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 549 } else { 550 /* 551 * Implement correct POSIX saved-id behavior. 552 * 553 * XXX: It's not clear that the existing behavior is 554 * POSIX-compliant. A number of sources indicate that the 555 * saved uid/gid should only be updated if the new ruid is 556 * not equal to the old ruid, or the new euid is not equal 557 * to the old euid and the new euid is not equal to the old 558 * ruid. The FreeBSD code always updates the saved uid/gid. 559 * Also, this code uses the new (replaced) euid and egid as 560 * the source, which may or may not be the right ones to use. 561 */ 562 if (oldcred->cr_svuid != oldcred->cr_uid || 563 oldcred->cr_svgid != oldcred->cr_gid) { 564 VOP_UNLOCK(imgp->vp); 565 imgp->newcred = crdup(oldcred); 566 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 567 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 568 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 569 } 570 } 571 /* The new credentials are installed into the process later. */ 572 573 /* 574 * Do the best to calculate the full path to the image file. 575 */ 576 if (args->fname != NULL && args->fname[0] == '/') 577 imgp->execpath = args->fname; 578 else { 579 VOP_UNLOCK(imgp->vp); 580 if (vn_fullpath(imgp->vp, &imgp->execpath, &imgp->freepath) != 0) 581 imgp->execpath = args->fname; 582 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 583 } 584 585 /* 586 * If the current process has a special image activator it 587 * wants to try first, call it. For example, emulating shell 588 * scripts differently. 589 */ 590 error = -1; 591 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 592 error = img_first(imgp); 593 594 /* 595 * Loop through the list of image activators, calling each one. 596 * An activator returns -1 if there is no match, 0 on success, 597 * and an error otherwise. 598 */ 599 for (i = 0; error == -1 && execsw[i]; ++i) { 600 if (execsw[i]->ex_imgact == NULL || 601 execsw[i]->ex_imgact == img_first) { 602 continue; 603 } 604 error = (*execsw[i]->ex_imgact)(imgp); 605 } 606 607 if (error) { 608 if (error == -1) 609 error = ENOEXEC; 610 goto exec_fail_dealloc; 611 } 612 613 /* 614 * Special interpreter operation, cleanup and loop up to try to 615 * activate the interpreter. 616 */ 617 if (imgp->interpreted) { 618 exec_unmap_first_page(imgp); 619 /* 620 * The text reference needs to be removed for scripts. 621 * There is a short period before we determine that 622 * something is a script where text reference is active. 623 * The vnode lock is held over this entire period 624 * so nothing should illegitimately be blocked. 625 */ 626 MPASS(imgp->textset); 627 VOP_UNSET_TEXT_CHECKED(newtextvp); 628 imgp->textset = false; 629 /* free name buffer and old vnode */ 630 if (args->fname != NULL) 631 NDFREE(&nd, NDF_ONLY_PNBUF); 632 #ifdef MAC 633 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 634 #endif 635 if (imgp->opened) { 636 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 637 imgp->opened = 0; 638 } 639 vput(newtextvp); 640 vm_object_deallocate(imgp->object); 641 imgp->object = NULL; 642 imgp->credential_setid = false; 643 if (imgp->newcred != NULL) { 644 crfree(imgp->newcred); 645 imgp->newcred = NULL; 646 } 647 imgp->execpath = NULL; 648 free(imgp->freepath, M_TEMP); 649 imgp->freepath = NULL; 650 /* set new name to that of the interpreter */ 651 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 652 SAVENAME, UIO_SYSSPACE, imgp->interpreter_name, td); 653 args->fname = imgp->interpreter_name; 654 goto interpret; 655 } 656 657 /* 658 * NB: We unlock the vnode here because it is believed that none 659 * of the sv_copyout_strings/sv_fixup operations require the vnode. 660 */ 661 VOP_UNLOCK(imgp->vp); 662 663 if (disallow_high_osrel && 664 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 665 error = ENOEXEC; 666 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 667 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 668 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 669 goto exec_fail_dealloc; 670 } 671 672 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 673 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 674 sys_cap_enter(td, NULL); 675 676 /* 677 * Copy out strings (args and env) and initialize stack base. 678 */ 679 error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base); 680 if (error != 0) { 681 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 682 goto exec_fail_dealloc; 683 } 684 685 /* 686 * Stack setup. 687 */ 688 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 689 if (error != 0) { 690 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 691 goto exec_fail_dealloc; 692 } 693 694 if (args->fdp != NULL) { 695 /* Install a brand new file descriptor table. */ 696 fdinstall_remapped(td, args->fdp); 697 args->fdp = NULL; 698 } else { 699 /* 700 * Keep on using the existing file descriptor table. For 701 * security and other reasons, the file descriptor table 702 * cannot be shared after an exec. 703 */ 704 fdunshare(td); 705 pdunshare(td); 706 /* close files on exec */ 707 fdcloseexec(td); 708 } 709 710 /* 711 * Malloc things before we need locks. 712 */ 713 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 714 /* Cache arguments if they fit inside our allowance */ 715 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 716 newargs = pargs_alloc(i); 717 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 718 } 719 720 /* 721 * For security and other reasons, signal handlers cannot 722 * be shared after an exec. The new process gets a copy of the old 723 * handlers. In execsigs(), the new process will have its signals 724 * reset. 725 */ 726 if (sigacts_shared(p->p_sigacts)) { 727 oldsigacts = p->p_sigacts; 728 newsigacts = sigacts_alloc(); 729 sigacts_copy(newsigacts, oldsigacts); 730 } 731 732 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 733 734 PROC_LOCK(p); 735 if (oldsigacts) 736 p->p_sigacts = newsigacts; 737 /* Stop profiling */ 738 stopprofclock(p); 739 740 /* reset caught signals */ 741 execsigs(p); 742 743 /* name this process - nameiexec(p, ndp) */ 744 bzero(p->p_comm, sizeof(p->p_comm)); 745 if (args->fname) 746 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 747 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 748 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 749 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 750 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 751 #ifdef KTR 752 sched_clear_tdname(td); 753 #endif 754 755 /* 756 * mark as execed, wakeup the process that vforked (if any) and tell 757 * it that it now has its own resources back 758 */ 759 p->p_flag |= P_EXEC; 760 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 761 p->p_flag2 &= ~P2_NOTRACE; 762 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 763 p->p_flag2 &= ~P2_STKGAP_DISABLE; 764 if (p->p_flag & P_PPWAIT) { 765 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 766 cv_broadcast(&p->p_pwait); 767 /* STOPs are no longer ignored, arrange for AST */ 768 signotify(td); 769 } 770 771 /* 772 * Implement image setuid/setgid installation. 773 */ 774 if (imgp->credential_setid) { 775 /* 776 * Turn off syscall tracing for set-id programs, except for 777 * root. Record any set-id flags first to make sure that 778 * we do not regain any tracing during a possible block. 779 */ 780 setsugid(p); 781 782 #ifdef KTRACE 783 if (p->p_tracecred != NULL && 784 priv_check_cred(p->p_tracecred, PRIV_DEBUG_DIFFCRED)) 785 ktrprocexec(p, &tracecred, &tracevp); 786 #endif 787 /* 788 * Close any file descriptors 0..2 that reference procfs, 789 * then make sure file descriptors 0..2 are in use. 790 * 791 * Both fdsetugidsafety() and fdcheckstd() may call functions 792 * taking sleepable locks, so temporarily drop our locks. 793 */ 794 PROC_UNLOCK(p); 795 VOP_UNLOCK(imgp->vp); 796 fdsetugidsafety(td); 797 error = fdcheckstd(td); 798 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 799 if (error != 0) 800 goto exec_fail_dealloc; 801 PROC_LOCK(p); 802 #ifdef MAC 803 if (will_transition) { 804 mac_vnode_execve_transition(oldcred, imgp->newcred, 805 imgp->vp, interpvplabel, imgp); 806 } 807 #endif 808 } else { 809 if (oldcred->cr_uid == oldcred->cr_ruid && 810 oldcred->cr_gid == oldcred->cr_rgid) 811 p->p_flag &= ~P_SUGID; 812 } 813 /* 814 * Set the new credentials. 815 */ 816 if (imgp->newcred != NULL) { 817 proc_set_cred(p, imgp->newcred); 818 crfree(oldcred); 819 oldcred = NULL; 820 } 821 822 /* 823 * Store the vp for use in procfs. This vnode was referenced by namei 824 * or fgetvp_exec. 825 */ 826 oldtextvp = p->p_textvp; 827 p->p_textvp = newtextvp; 828 829 #ifdef KDTRACE_HOOKS 830 /* 831 * Tell the DTrace fasttrap provider about the exec if it 832 * has declared an interest. 833 */ 834 if (dtrace_fasttrap_exec) 835 dtrace_fasttrap_exec(p); 836 #endif 837 838 /* 839 * Notify others that we exec'd, and clear the P_INEXEC flag 840 * as we're now a bona fide freshly-execed process. 841 */ 842 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 843 p->p_flag &= ~P_INEXEC; 844 845 /* clear "fork but no exec" flag, as we _are_ execing */ 846 p->p_acflag &= ~AFORK; 847 848 /* 849 * Free any previous argument cache and replace it with 850 * the new argument cache, if any. 851 */ 852 oldargs = p->p_args; 853 p->p_args = newargs; 854 newargs = NULL; 855 856 PROC_UNLOCK(p); 857 858 #ifdef HWPMC_HOOKS 859 /* 860 * Check if system-wide sampling is in effect or if the 861 * current process is using PMCs. If so, do exec() time 862 * processing. This processing needs to happen AFTER the 863 * P_INEXEC flag is cleared. 864 */ 865 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 866 VOP_UNLOCK(imgp->vp); 867 pe.pm_credentialschanged = credential_changing; 868 pe.pm_entryaddr = imgp->entry_addr; 869 870 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 871 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 872 } 873 #endif 874 875 /* Set values passed into the program in registers. */ 876 (*p->p_sysent->sv_setregs)(td, imgp, stack_base); 877 878 VOP_MMAPPED(imgp->vp); 879 880 SDT_PROBE1(proc, , , exec__success, args->fname); 881 882 exec_fail_dealloc: 883 if (error != 0) { 884 p->p_osrel = orig_osrel; 885 p->p_fctl0 = orig_fctl0; 886 } 887 888 if (imgp->firstpage != NULL) 889 exec_unmap_first_page(imgp); 890 891 if (imgp->vp != NULL) { 892 if (args->fname) 893 NDFREE(&nd, NDF_ONLY_PNBUF); 894 if (imgp->opened) 895 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 896 if (imgp->textset) 897 VOP_UNSET_TEXT_CHECKED(imgp->vp); 898 if (error != 0) 899 vput(imgp->vp); 900 else 901 VOP_UNLOCK(imgp->vp); 902 } 903 904 if (imgp->object != NULL) 905 vm_object_deallocate(imgp->object); 906 907 free(imgp->freepath, M_TEMP); 908 909 if (error == 0) { 910 if (p->p_ptevents & PTRACE_EXEC) { 911 PROC_LOCK(p); 912 if (p->p_ptevents & PTRACE_EXEC) 913 td->td_dbgflags |= TDB_EXEC; 914 PROC_UNLOCK(p); 915 } 916 } else { 917 exec_fail: 918 /* we're done here, clear P_INEXEC */ 919 PROC_LOCK(p); 920 p->p_flag &= ~P_INEXEC; 921 PROC_UNLOCK(p); 922 923 SDT_PROBE1(proc, , , exec__failure, error); 924 } 925 926 if (imgp->newcred != NULL && oldcred != NULL) 927 crfree(imgp->newcred); 928 929 #ifdef MAC 930 mac_execve_exit(imgp); 931 mac_execve_interpreter_exit(interpvplabel); 932 #endif 933 exec_free_args(args); 934 935 /* 936 * Handle deferred decrement of ref counts. 937 */ 938 if (oldtextvp != NULL) 939 vrele(oldtextvp); 940 #ifdef KTRACE 941 if (tracevp != NULL) 942 vrele(tracevp); 943 if (tracecred != NULL) 944 crfree(tracecred); 945 #endif 946 pargs_drop(oldargs); 947 pargs_drop(newargs); 948 if (oldsigacts != NULL) 949 sigacts_free(oldsigacts); 950 if (euip != NULL) 951 uifree(euip); 952 953 if (error && imgp->vmspace_destroyed) { 954 /* sorry, no more process anymore. exit gracefully */ 955 exec_cleanup(td, oldvmspace); 956 exit1(td, 0, SIGABRT); 957 /* NOT REACHED */ 958 } 959 960 #ifdef KTRACE 961 if (error == 0) 962 ktrprocctor(p); 963 #endif 964 965 /* 966 * We don't want cpu_set_syscall_retval() to overwrite any of 967 * the register values put in place by exec_setregs(). 968 * Implementations of cpu_set_syscall_retval() will leave 969 * registers unmodified when returning EJUSTRETURN. 970 */ 971 return (error == 0 ? EJUSTRETURN : error); 972 } 973 974 void 975 exec_cleanup(struct thread *td, struct vmspace *oldvmspace) 976 { 977 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 978 KASSERT(td->td_proc->p_vmspace != oldvmspace, 979 ("oldvmspace still used")); 980 vmspace_free(oldvmspace); 981 td->td_pflags &= ~TDP_EXECVMSPC; 982 } 983 } 984 985 int 986 exec_map_first_page(struct image_params *imgp) 987 { 988 vm_object_t object; 989 vm_page_t m; 990 int error; 991 992 if (imgp->firstpage != NULL) 993 exec_unmap_first_page(imgp); 994 995 object = imgp->vp->v_object; 996 if (object == NULL) 997 return (EACCES); 998 #if VM_NRESERVLEVEL > 0 999 if ((object->flags & OBJ_COLORED) == 0) { 1000 VM_OBJECT_WLOCK(object); 1001 vm_object_color(object, 0); 1002 VM_OBJECT_WUNLOCK(object); 1003 } 1004 #endif 1005 error = vm_page_grab_valid_unlocked(&m, object, 0, 1006 VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) | 1007 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED); 1008 1009 if (error != VM_PAGER_OK) 1010 return (EIO); 1011 imgp->firstpage = sf_buf_alloc(m, 0); 1012 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1013 1014 return (0); 1015 } 1016 1017 void 1018 exec_unmap_first_page(struct image_params *imgp) 1019 { 1020 vm_page_t m; 1021 1022 if (imgp->firstpage != NULL) { 1023 m = sf_buf_page(imgp->firstpage); 1024 sf_buf_free(imgp->firstpage); 1025 imgp->firstpage = NULL; 1026 vm_page_unwire(m, PQ_ACTIVE); 1027 } 1028 } 1029 1030 /* 1031 * Destroy old address space, and allocate a new stack. 1032 * The new stack is only sgrowsiz large because it is grown 1033 * automatically on a page fault. 1034 */ 1035 int 1036 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1037 { 1038 int error; 1039 struct proc *p = imgp->proc; 1040 struct vmspace *vmspace = p->p_vmspace; 1041 struct thread *td = curthread; 1042 vm_object_t obj; 1043 struct rlimit rlim_stack; 1044 vm_offset_t sv_minuser, stack_addr; 1045 vm_map_t map; 1046 vm_prot_t stack_prot; 1047 u_long ssiz; 1048 1049 imgp->vmspace_destroyed = 1; 1050 imgp->sysent = sv; 1051 1052 sigfastblock_clear(td); 1053 umtx_exec(p); 1054 itimers_exec(p); 1055 if (sv->sv_onexec != NULL) 1056 sv->sv_onexec(p, imgp); 1057 1058 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1059 1060 /* 1061 * Blow away entire process VM, if address space not shared, 1062 * otherwise, create a new VM space so that other threads are 1063 * not disrupted 1064 */ 1065 map = &vmspace->vm_map; 1066 if (map_at_zero) 1067 sv_minuser = sv->sv_minuser; 1068 else 1069 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1070 if (refcount_load(&vmspace->vm_refcnt) == 1 && 1071 vm_map_min(map) == sv_minuser && 1072 vm_map_max(map) == sv->sv_maxuser && 1073 cpu_exec_vmspace_reuse(p, map)) { 1074 shmexit(vmspace); 1075 pmap_remove_pages(vmspace_pmap(vmspace)); 1076 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1077 /* 1078 * An exec terminates mlockall(MCL_FUTURE). 1079 * ASLR and W^X states must be re-evaluated. 1080 */ 1081 vm_map_lock(map); 1082 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1083 MAP_ASLR_IGNSTART | MAP_WXORX); 1084 vm_map_unlock(map); 1085 } else { 1086 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1087 if (error) 1088 return (error); 1089 vmspace = p->p_vmspace; 1090 map = &vmspace->vm_map; 1091 } 1092 map->flags |= imgp->map_flags; 1093 1094 /* Map a shared page */ 1095 obj = sv->sv_shared_page_obj; 1096 if (obj != NULL) { 1097 vm_object_reference(obj); 1098 error = vm_map_fixed(map, obj, 0, 1099 sv->sv_shared_page_base, sv->sv_shared_page_len, 1100 VM_PROT_READ | VM_PROT_EXECUTE, 1101 VM_PROT_READ | VM_PROT_EXECUTE, 1102 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1103 if (error != KERN_SUCCESS) { 1104 vm_object_deallocate(obj); 1105 return (vm_mmap_to_errno(error)); 1106 } 1107 } 1108 1109 /* Allocate a new stack */ 1110 if (imgp->stack_sz != 0) { 1111 ssiz = trunc_page(imgp->stack_sz); 1112 PROC_LOCK(p); 1113 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1114 PROC_UNLOCK(p); 1115 if (ssiz > rlim_stack.rlim_max) 1116 ssiz = rlim_stack.rlim_max; 1117 if (ssiz > rlim_stack.rlim_cur) { 1118 rlim_stack.rlim_cur = ssiz; 1119 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1120 } 1121 } else if (sv->sv_maxssiz != NULL) { 1122 ssiz = *sv->sv_maxssiz; 1123 } else { 1124 ssiz = maxssiz; 1125 } 1126 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1127 if (ssiz < imgp->eff_stack_sz) 1128 imgp->eff_stack_sz = ssiz; 1129 stack_addr = sv->sv_usrstack - ssiz; 1130 stack_prot = obj != NULL && imgp->stack_prot != 0 ? 1131 imgp->stack_prot : sv->sv_stackprot; 1132 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, stack_prot, 1133 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1134 if (error != KERN_SUCCESS) { 1135 uprintf("exec_new_vmspace: mapping stack size %#jx prot %#x " 1136 "failed mach error %d errno %d\n", (uintmax_t)ssiz, 1137 stack_prot, error, vm_mmap_to_errno(error)); 1138 return (vm_mmap_to_errno(error)); 1139 } 1140 1141 /* 1142 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1143 * are still used to enforce the stack rlimit on the process stack. 1144 */ 1145 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1146 vmspace->vm_maxsaddr = (char *)stack_addr; 1147 1148 return (0); 1149 } 1150 1151 /* 1152 * Copy out argument and environment strings from the old process address 1153 * space into the temporary string buffer. 1154 */ 1155 int 1156 exec_copyin_args(struct image_args *args, const char *fname, 1157 enum uio_seg segflg, char **argv, char **envv) 1158 { 1159 u_long arg, env; 1160 int error; 1161 1162 bzero(args, sizeof(*args)); 1163 if (argv == NULL) 1164 return (EFAULT); 1165 1166 /* 1167 * Allocate demand-paged memory for the file name, argument, and 1168 * environment strings. 1169 */ 1170 error = exec_alloc_args(args); 1171 if (error != 0) 1172 return (error); 1173 1174 /* 1175 * Copy the file name. 1176 */ 1177 error = exec_args_add_fname(args, fname, segflg); 1178 if (error != 0) 1179 goto err_exit; 1180 1181 /* 1182 * extract arguments first 1183 */ 1184 for (;;) { 1185 error = fueword(argv++, &arg); 1186 if (error == -1) { 1187 error = EFAULT; 1188 goto err_exit; 1189 } 1190 if (arg == 0) 1191 break; 1192 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1193 UIO_USERSPACE); 1194 if (error != 0) 1195 goto err_exit; 1196 } 1197 1198 /* 1199 * extract environment strings 1200 */ 1201 if (envv) { 1202 for (;;) { 1203 error = fueword(envv++, &env); 1204 if (error == -1) { 1205 error = EFAULT; 1206 goto err_exit; 1207 } 1208 if (env == 0) 1209 break; 1210 error = exec_args_add_env(args, 1211 (char *)(uintptr_t)env, UIO_USERSPACE); 1212 if (error != 0) 1213 goto err_exit; 1214 } 1215 } 1216 1217 return (0); 1218 1219 err_exit: 1220 exec_free_args(args); 1221 return (error); 1222 } 1223 1224 int 1225 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1226 const void *data, size_t datalen, const int *fds, size_t fdslen) 1227 { 1228 struct filedesc *ofdp; 1229 const char *p; 1230 int *kfds; 1231 int error; 1232 1233 memset(args, '\0', sizeof(*args)); 1234 ofdp = td->td_proc->p_fd; 1235 if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles) 1236 return (E2BIG); 1237 error = exec_alloc_args(args); 1238 if (error != 0) 1239 return (error); 1240 1241 args->begin_argv = args->buf; 1242 args->stringspace = ARG_MAX; 1243 1244 if (datalen > 0) { 1245 /* 1246 * Argument buffer has been provided. Copy it into the 1247 * kernel as a single string and add a terminating null 1248 * byte. 1249 */ 1250 error = copyin(data, args->begin_argv, datalen); 1251 if (error != 0) 1252 goto err_exit; 1253 args->begin_argv[datalen] = '\0'; 1254 args->endp = args->begin_argv + datalen + 1; 1255 args->stringspace -= datalen + 1; 1256 1257 /* 1258 * Traditional argument counting. Count the number of 1259 * null bytes. 1260 */ 1261 for (p = args->begin_argv; p < args->endp; ++p) 1262 if (*p == '\0') 1263 ++args->argc; 1264 } else { 1265 /* No argument buffer provided. */ 1266 args->endp = args->begin_argv; 1267 } 1268 1269 /* Create new file descriptor table. */ 1270 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1271 error = copyin(fds, kfds, fdslen * sizeof(int)); 1272 if (error != 0) { 1273 free(kfds, M_TEMP); 1274 goto err_exit; 1275 } 1276 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1277 free(kfds, M_TEMP); 1278 if (error != 0) 1279 goto err_exit; 1280 1281 return (0); 1282 err_exit: 1283 exec_free_args(args); 1284 return (error); 1285 } 1286 1287 struct exec_args_kva { 1288 vm_offset_t addr; 1289 u_int gen; 1290 SLIST_ENTRY(exec_args_kva) next; 1291 }; 1292 1293 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1294 1295 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1296 static struct mtx exec_args_kva_mtx; 1297 static u_int exec_args_gen; 1298 1299 static void 1300 exec_prealloc_args_kva(void *arg __unused) 1301 { 1302 struct exec_args_kva *argkva; 1303 u_int i; 1304 1305 SLIST_INIT(&exec_args_kva_freelist); 1306 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1307 for (i = 0; i < exec_map_entries; i++) { 1308 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1309 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1310 argkva->gen = exec_args_gen; 1311 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1312 } 1313 } 1314 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1315 1316 static vm_offset_t 1317 exec_alloc_args_kva(void **cookie) 1318 { 1319 struct exec_args_kva *argkva; 1320 1321 argkva = (void *)atomic_readandclear_ptr( 1322 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1323 if (argkva == NULL) { 1324 mtx_lock(&exec_args_kva_mtx); 1325 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1326 (void)mtx_sleep(&exec_args_kva_freelist, 1327 &exec_args_kva_mtx, 0, "execkva", 0); 1328 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1329 mtx_unlock(&exec_args_kva_mtx); 1330 } 1331 *(struct exec_args_kva **)cookie = argkva; 1332 return (argkva->addr); 1333 } 1334 1335 static void 1336 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1337 { 1338 vm_offset_t base; 1339 1340 base = argkva->addr; 1341 if (argkva->gen != gen) { 1342 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1343 MADV_FREE); 1344 argkva->gen = gen; 1345 } 1346 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1347 (uintptr_t)NULL, (uintptr_t)argkva)) { 1348 mtx_lock(&exec_args_kva_mtx); 1349 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1350 wakeup_one(&exec_args_kva_freelist); 1351 mtx_unlock(&exec_args_kva_mtx); 1352 } 1353 } 1354 1355 static void 1356 exec_free_args_kva(void *cookie) 1357 { 1358 1359 exec_release_args_kva(cookie, exec_args_gen); 1360 } 1361 1362 static void 1363 exec_args_kva_lowmem(void *arg __unused) 1364 { 1365 SLIST_HEAD(, exec_args_kva) head; 1366 struct exec_args_kva *argkva; 1367 u_int gen; 1368 int i; 1369 1370 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1371 1372 /* 1373 * Force an madvise of each KVA range. Any currently allocated ranges 1374 * will have MADV_FREE applied once they are freed. 1375 */ 1376 SLIST_INIT(&head); 1377 mtx_lock(&exec_args_kva_mtx); 1378 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1379 mtx_unlock(&exec_args_kva_mtx); 1380 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1381 SLIST_REMOVE_HEAD(&head, next); 1382 exec_release_args_kva(argkva, gen); 1383 } 1384 1385 CPU_FOREACH(i) { 1386 argkva = (void *)atomic_readandclear_ptr( 1387 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1388 if (argkva != NULL) 1389 exec_release_args_kva(argkva, gen); 1390 } 1391 } 1392 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1393 EVENTHANDLER_PRI_ANY); 1394 1395 /* 1396 * Allocate temporary demand-paged, zero-filled memory for the file name, 1397 * argument, and environment strings. 1398 */ 1399 int 1400 exec_alloc_args(struct image_args *args) 1401 { 1402 1403 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1404 return (0); 1405 } 1406 1407 void 1408 exec_free_args(struct image_args *args) 1409 { 1410 1411 if (args->buf != NULL) { 1412 exec_free_args_kva(args->bufkva); 1413 args->buf = NULL; 1414 } 1415 if (args->fname_buf != NULL) { 1416 free(args->fname_buf, M_TEMP); 1417 args->fname_buf = NULL; 1418 } 1419 if (args->fdp != NULL) 1420 fdescfree_remapped(args->fdp); 1421 } 1422 1423 /* 1424 * A set to functions to fill struct image args. 1425 * 1426 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1427 * fname) before the other functions. All exec_args_add_arg() calls must 1428 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1429 * may be called any time after exec_args_add_fname(). 1430 * 1431 * exec_args_add_fname() - install path to be executed 1432 * exec_args_add_arg() - append an argument string 1433 * exec_args_add_env() - append an env string 1434 * exec_args_adjust_args() - adjust location of the argument list to 1435 * allow new arguments to be prepended 1436 */ 1437 int 1438 exec_args_add_fname(struct image_args *args, const char *fname, 1439 enum uio_seg segflg) 1440 { 1441 int error; 1442 size_t length; 1443 1444 KASSERT(args->fname == NULL, ("fname already appended")); 1445 KASSERT(args->endp == NULL, ("already appending to args")); 1446 1447 if (fname != NULL) { 1448 args->fname = args->buf; 1449 error = segflg == UIO_SYSSPACE ? 1450 copystr(fname, args->fname, PATH_MAX, &length) : 1451 copyinstr(fname, args->fname, PATH_MAX, &length); 1452 if (error != 0) 1453 return (error == ENAMETOOLONG ? E2BIG : error); 1454 } else 1455 length = 0; 1456 1457 /* Set up for _arg_*()/_env_*() */ 1458 args->endp = args->buf + length; 1459 /* begin_argv must be set and kept updated */ 1460 args->begin_argv = args->endp; 1461 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1462 ("too little space remaining for arguments %zu < %zu", 1463 exec_map_entry_size - length, (size_t)ARG_MAX)); 1464 args->stringspace = ARG_MAX; 1465 1466 return (0); 1467 } 1468 1469 static int 1470 exec_args_add_str(struct image_args *args, const char *str, 1471 enum uio_seg segflg, int *countp) 1472 { 1473 int error; 1474 size_t length; 1475 1476 KASSERT(args->endp != NULL, ("endp not initialized")); 1477 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1478 1479 error = (segflg == UIO_SYSSPACE) ? 1480 copystr(str, args->endp, args->stringspace, &length) : 1481 copyinstr(str, args->endp, args->stringspace, &length); 1482 if (error != 0) 1483 return (error == ENAMETOOLONG ? E2BIG : error); 1484 args->stringspace -= length; 1485 args->endp += length; 1486 (*countp)++; 1487 1488 return (0); 1489 } 1490 1491 int 1492 exec_args_add_arg(struct image_args *args, const char *argp, 1493 enum uio_seg segflg) 1494 { 1495 1496 KASSERT(args->envc == 0, ("appending args after env")); 1497 1498 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1499 } 1500 1501 int 1502 exec_args_add_env(struct image_args *args, const char *envp, 1503 enum uio_seg segflg) 1504 { 1505 1506 if (args->envc == 0) 1507 args->begin_envv = args->endp; 1508 1509 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1510 } 1511 1512 int 1513 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1514 { 1515 ssize_t offset; 1516 1517 KASSERT(args->endp != NULL, ("endp not initialized")); 1518 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1519 1520 offset = extend - consume; 1521 if (args->stringspace < offset) 1522 return (E2BIG); 1523 memmove(args->begin_argv + extend, args->begin_argv + consume, 1524 args->endp - args->begin_argv + consume); 1525 if (args->envc > 0) 1526 args->begin_envv += offset; 1527 args->endp += offset; 1528 args->stringspace -= offset; 1529 return (0); 1530 } 1531 1532 char * 1533 exec_args_get_begin_envv(struct image_args *args) 1534 { 1535 1536 KASSERT(args->endp != NULL, ("endp not initialized")); 1537 1538 if (args->envc > 0) 1539 return (args->begin_envv); 1540 return (args->endp); 1541 } 1542 1543 void 1544 exec_stackgap(struct image_params *imgp, uintptr_t *dp) 1545 { 1546 if (imgp->sysent->sv_stackgap == NULL || 1547 (imgp->proc->p_fctl0 & (NT_FREEBSD_FCTL_ASLR_DISABLE | 1548 NT_FREEBSD_FCTL_ASG_DISABLE)) != 0 || 1549 (imgp->map_flags & MAP_ASLR) == 0) 1550 return; 1551 imgp->sysent->sv_stackgap(imgp, dp); 1552 } 1553 1554 /* 1555 * Copy strings out to the new process address space, constructing new arg 1556 * and env vector tables. Return a pointer to the base so that it can be used 1557 * as the initial stack pointer. 1558 */ 1559 int 1560 exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base) 1561 { 1562 int argc, envc; 1563 char **vectp; 1564 char *stringp; 1565 uintptr_t destp, ustringp; 1566 struct ps_strings *arginfo; 1567 struct proc *p; 1568 size_t execpath_len; 1569 int error, szsigcode, szps; 1570 char canary[sizeof(long) * 8]; 1571 1572 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1573 /* 1574 * Calculate string base and vector table pointers. 1575 * Also deal with signal trampoline code for this exec type. 1576 */ 1577 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1578 execpath_len = strlen(imgp->execpath) + 1; 1579 else 1580 execpath_len = 0; 1581 p = imgp->proc; 1582 szsigcode = 0; 1583 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1584 imgp->ps_strings = arginfo; 1585 if (p->p_sysent->sv_sigcode_base == 0) { 1586 if (p->p_sysent->sv_szsigcode != NULL) 1587 szsigcode = *(p->p_sysent->sv_szsigcode); 1588 } 1589 destp = (uintptr_t)arginfo; 1590 1591 /* 1592 * install sigcode 1593 */ 1594 if (szsigcode != 0) { 1595 destp -= szsigcode; 1596 destp = rounddown2(destp, sizeof(void *)); 1597 error = copyout(p->p_sysent->sv_sigcode, (void *)destp, 1598 szsigcode); 1599 if (error != 0) 1600 return (error); 1601 } 1602 1603 /* 1604 * Copy the image path for the rtld. 1605 */ 1606 if (execpath_len != 0) { 1607 destp -= execpath_len; 1608 destp = rounddown2(destp, sizeof(void *)); 1609 imgp->execpathp = (void *)destp; 1610 error = copyout(imgp->execpath, imgp->execpathp, execpath_len); 1611 if (error != 0) 1612 return (error); 1613 } 1614 1615 /* 1616 * Prepare the canary for SSP. 1617 */ 1618 arc4rand(canary, sizeof(canary), 0); 1619 destp -= sizeof(canary); 1620 imgp->canary = (void *)destp; 1621 error = copyout(canary, imgp->canary, sizeof(canary)); 1622 if (error != 0) 1623 return (error); 1624 imgp->canarylen = sizeof(canary); 1625 1626 /* 1627 * Prepare the pagesizes array. 1628 */ 1629 destp -= szps; 1630 destp = rounddown2(destp, sizeof(void *)); 1631 imgp->pagesizes = (void *)destp; 1632 error = copyout(pagesizes, imgp->pagesizes, szps); 1633 if (error != 0) 1634 return (error); 1635 imgp->pagesizeslen = szps; 1636 1637 /* 1638 * Allocate room for the argument and environment strings. 1639 */ 1640 destp -= ARG_MAX - imgp->args->stringspace; 1641 destp = rounddown2(destp, sizeof(void *)); 1642 ustringp = destp; 1643 1644 exec_stackgap(imgp, &destp); 1645 1646 if (imgp->auxargs) { 1647 /* 1648 * Allocate room on the stack for the ELF auxargs 1649 * array. It has up to AT_COUNT entries. 1650 */ 1651 destp -= AT_COUNT * sizeof(Elf_Auxinfo); 1652 destp = rounddown2(destp, sizeof(void *)); 1653 } 1654 1655 vectp = (char **)destp; 1656 1657 /* 1658 * Allocate room for the argv[] and env vectors including the 1659 * terminating NULL pointers. 1660 */ 1661 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1662 1663 /* 1664 * vectp also becomes our initial stack base 1665 */ 1666 *stack_base = (uintptr_t)vectp; 1667 1668 stringp = imgp->args->begin_argv; 1669 argc = imgp->args->argc; 1670 envc = imgp->args->envc; 1671 1672 /* 1673 * Copy out strings - arguments and environment. 1674 */ 1675 error = copyout(stringp, (void *)ustringp, 1676 ARG_MAX - imgp->args->stringspace); 1677 if (error != 0) 1678 return (error); 1679 1680 /* 1681 * Fill in "ps_strings" struct for ps, w, etc. 1682 */ 1683 imgp->argv = vectp; 1684 if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 || 1685 suword32(&arginfo->ps_nargvstr, argc) != 0) 1686 return (EFAULT); 1687 1688 /* 1689 * Fill in argument portion of vector table. 1690 */ 1691 for (; argc > 0; --argc) { 1692 if (suword(vectp++, ustringp) != 0) 1693 return (EFAULT); 1694 while (*stringp++ != 0) 1695 ustringp++; 1696 ustringp++; 1697 } 1698 1699 /* a null vector table pointer separates the argp's from the envp's */ 1700 if (suword(vectp++, 0) != 0) 1701 return (EFAULT); 1702 1703 imgp->envv = vectp; 1704 if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 || 1705 suword32(&arginfo->ps_nenvstr, envc) != 0) 1706 return (EFAULT); 1707 1708 /* 1709 * Fill in environment portion of vector table. 1710 */ 1711 for (; envc > 0; --envc) { 1712 if (suword(vectp++, ustringp) != 0) 1713 return (EFAULT); 1714 while (*stringp++ != 0) 1715 ustringp++; 1716 ustringp++; 1717 } 1718 1719 /* end of vector table is a null pointer */ 1720 if (suword(vectp, 0) != 0) 1721 return (EFAULT); 1722 1723 if (imgp->auxargs) { 1724 vectp++; 1725 error = imgp->sysent->sv_copyout_auxargs(imgp, 1726 (uintptr_t)vectp); 1727 if (error != 0) 1728 return (error); 1729 } 1730 1731 return (0); 1732 } 1733 1734 /* 1735 * Check permissions of file to execute. 1736 * Called with imgp->vp locked. 1737 * Return 0 for success or error code on failure. 1738 */ 1739 int 1740 exec_check_permissions(struct image_params *imgp) 1741 { 1742 struct vnode *vp = imgp->vp; 1743 struct vattr *attr = imgp->attr; 1744 struct thread *td; 1745 int error; 1746 1747 td = curthread; 1748 1749 /* Get file attributes */ 1750 error = VOP_GETATTR(vp, attr, td->td_ucred); 1751 if (error) 1752 return (error); 1753 1754 #ifdef MAC 1755 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1756 if (error) 1757 return (error); 1758 #endif 1759 1760 /* 1761 * 1) Check if file execution is disabled for the filesystem that 1762 * this file resides on. 1763 * 2) Ensure that at least one execute bit is on. Otherwise, a 1764 * privileged user will always succeed, and we don't want this 1765 * to happen unless the file really is executable. 1766 * 3) Ensure that the file is a regular file. 1767 */ 1768 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1769 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1770 (attr->va_type != VREG)) 1771 return (EACCES); 1772 1773 /* 1774 * Zero length files can't be exec'd 1775 */ 1776 if (attr->va_size == 0) 1777 return (ENOEXEC); 1778 1779 /* 1780 * Check for execute permission to file based on current credentials. 1781 */ 1782 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1783 if (error) 1784 return (error); 1785 1786 /* 1787 * Check number of open-for-writes on the file and deny execution 1788 * if there are any. 1789 * 1790 * Add a text reference now so no one can write to the 1791 * executable while we're activating it. 1792 * 1793 * Remember if this was set before and unset it in case this is not 1794 * actually an executable image. 1795 */ 1796 error = VOP_SET_TEXT(vp); 1797 if (error != 0) 1798 return (error); 1799 imgp->textset = true; 1800 1801 /* 1802 * Call filesystem specific open routine (which does nothing in the 1803 * general case). 1804 */ 1805 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1806 if (error == 0) 1807 imgp->opened = 1; 1808 return (error); 1809 } 1810 1811 /* 1812 * Exec handler registration 1813 */ 1814 int 1815 exec_register(const struct execsw *execsw_arg) 1816 { 1817 const struct execsw **es, **xs, **newexecsw; 1818 u_int count = 2; /* New slot and trailing NULL */ 1819 1820 if (execsw) 1821 for (es = execsw; *es; es++) 1822 count++; 1823 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1824 xs = newexecsw; 1825 if (execsw) 1826 for (es = execsw; *es; es++) 1827 *xs++ = *es; 1828 *xs++ = execsw_arg; 1829 *xs = NULL; 1830 if (execsw) 1831 free(execsw, M_TEMP); 1832 execsw = newexecsw; 1833 return (0); 1834 } 1835 1836 int 1837 exec_unregister(const struct execsw *execsw_arg) 1838 { 1839 const struct execsw **es, **xs, **newexecsw; 1840 int count = 1; 1841 1842 if (execsw == NULL) 1843 panic("unregister with no handlers left?\n"); 1844 1845 for (es = execsw; *es; es++) { 1846 if (*es == execsw_arg) 1847 break; 1848 } 1849 if (*es == NULL) 1850 return (ENOENT); 1851 for (es = execsw; *es; es++) 1852 if (*es != execsw_arg) 1853 count++; 1854 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1855 xs = newexecsw; 1856 for (es = execsw; *es; es++) 1857 if (*es != execsw_arg) 1858 *xs++ = *es; 1859 *xs = NULL; 1860 if (execsw) 1861 free(execsw, M_TEMP); 1862 execsw = newexecsw; 1863 return (0); 1864 }
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