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/asan.h> 41 #include <sys/capsicum.h> 42 #include <sys/eventhandler.h> 43 #include <sys/exec.h> 44 #include <sys/fcntl.h> 45 #include <sys/filedesc.h> 46 #include <sys/imgact.h> 47 #include <sys/imgact_elf.h> 48 #include <sys/kernel.h> 49 #include <sys/lock.h> 50 #include <sys/malloc.h> 51 #include <sys/mman.h> 52 #include <sys/mount.h> 53 #include <sys/mutex.h> 54 #include <sys/namei.h> 55 #include <sys/priv.h> 56 #include <sys/proc.h> 57 #include <sys/ptrace.h> 58 #include <sys/resourcevar.h> 59 #include <sys/rwlock.h> 60 #include <sys/sched.h> 61 #include <sys/sdt.h> 62 #include <sys/sf_buf.h> 63 #include <sys/shm.h> 64 #include <sys/signalvar.h> 65 #include <sys/smp.h> 66 #include <sys/stat.h> 67 #include <sys/syscallsubr.h> 68 #include <sys/sysctl.h> 69 #include <sys/sysent.h> 70 #include <sys/sysproto.h> 71 #include <sys/timers.h> 72 #include <sys/umtx.h> 73 #include <sys/vnode.h> 74 #include <sys/wait.h> 75 #ifdef KTRACE 76 #include <sys/ktrace.h> 77 #endif 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <vm/pmap.h> 82 #include <vm/vm_page.h> 83 #include <vm/vm_map.h> 84 #include <vm/vm_kern.h> 85 #include <vm/vm_extern.h> 86 #include <vm/vm_object.h> 87 #include <vm/vm_pager.h> 88 89 #ifdef HWPMC_HOOKS 90 #include <sys/pmckern.h> 91 #endif 92 93 #include <machine/reg.h> 94 95 #include <security/audit/audit.h> 96 #include <security/mac/mac_framework.h> 97 98 #ifdef KDTRACE_HOOKS 99 #include <sys/dtrace_bsd.h> 100 dtrace_execexit_func_t dtrace_fasttrap_exec; 101 #endif 102 103 SDT_PROVIDER_DECLARE(proc); 104 SDT_PROBE_DEFINE1(proc, , , exec, "char *"); 105 SDT_PROBE_DEFINE1(proc, , , exec__failure, "int"); 106 SDT_PROBE_DEFINE1(proc, , , exec__success, "char *"); 107 108 MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); 109 110 int coredump_pack_fileinfo = 1; 111 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, 112 &coredump_pack_fileinfo, 0, 113 "Enable file path packing in 'procstat -f' coredump notes"); 114 115 int coredump_pack_vmmapinfo = 1; 116 SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, 117 &coredump_pack_vmmapinfo, 0, 118 "Enable file path packing in 'procstat -v' coredump notes"); 119 120 static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); 121 static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); 122 static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); 123 static int do_execve(struct thread *td, struct image_args *args, 124 struct mac *mac_p, struct vmspace *oldvmspace); 125 126 /* XXX This should be vm_size_t. */ 127 SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD| 128 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU", 129 "Location of process' ps_strings structure"); 130 131 /* XXX This should be vm_size_t. */ 132 SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD| 133 CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU", 134 "Top of process stack"); 135 136 SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE, 137 NULL, 0, sysctl_kern_stackprot, "I", 138 "Stack memory permissions"); 139 140 u_long ps_arg_cache_limit = PAGE_SIZE / 16; 141 SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 142 &ps_arg_cache_limit, 0, 143 "Process' command line characters cache limit"); 144 145 static int disallow_high_osrel; 146 SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW, 147 &disallow_high_osrel, 0, 148 "Disallow execution of binaries built for higher version of the world"); 149 150 static int map_at_zero = 0; 151 SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0, 152 "Permit processes to map an object at virtual address 0."); 153 154 int core_dump_can_intr = 1; 155 SYSCTL_INT(_kern, OID_AUTO, core_dump_can_intr, CTLFLAG_RWTUN, 156 &core_dump_can_intr, 0, 157 "Core dumping interruptible with SIGKILL"); 158 159 static int 160 sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS) 161 { 162 struct proc *p; 163 int error; 164 165 p = curproc; 166 #ifdef SCTL_MASK32 167 if (req->flags & SCTL_MASK32) { 168 unsigned int val; 169 val = (unsigned int)p->p_sysent->sv_psstrings; 170 error = SYSCTL_OUT(req, &val, sizeof(val)); 171 } else 172 #endif 173 error = SYSCTL_OUT(req, &p->p_sysent->sv_psstrings, 174 sizeof(p->p_sysent->sv_psstrings)); 175 return error; 176 } 177 178 static int 179 sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS) 180 { 181 struct proc *p; 182 int error; 183 184 p = curproc; 185 #ifdef SCTL_MASK32 186 if (req->flags & SCTL_MASK32) { 187 unsigned int val; 188 val = (unsigned int)p->p_sysent->sv_usrstack; 189 error = SYSCTL_OUT(req, &val, sizeof(val)); 190 } else 191 #endif 192 error = SYSCTL_OUT(req, &p->p_sysent->sv_usrstack, 193 sizeof(p->p_sysent->sv_usrstack)); 194 return error; 195 } 196 197 static int 198 sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS) 199 { 200 struct proc *p; 201 202 p = curproc; 203 return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot, 204 sizeof(p->p_sysent->sv_stackprot))); 205 } 206 207 /* 208 * Each of the items is a pointer to a `const struct execsw', hence the 209 * double pointer here. 210 */ 211 static const struct execsw **execsw; 212 213 #ifndef _SYS_SYSPROTO_H_ 214 struct execve_args { 215 char *fname; 216 char **argv; 217 char **envv; 218 }; 219 #endif 220 221 int 222 sys_execve(struct thread *td, struct execve_args *uap) 223 { 224 struct image_args args; 225 struct vmspace *oldvmspace; 226 int error; 227 228 error = pre_execve(td, &oldvmspace); 229 if (error != 0) 230 return (error); 231 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 232 uap->argv, uap->envv); 233 if (error == 0) 234 error = kern_execve(td, &args, NULL, oldvmspace); 235 post_execve(td, error, oldvmspace); 236 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 237 return (error); 238 } 239 240 #ifndef _SYS_SYSPROTO_H_ 241 struct fexecve_args { 242 int fd; 243 char **argv; 244 char **envv; 245 }; 246 #endif 247 int 248 sys_fexecve(struct thread *td, struct fexecve_args *uap) 249 { 250 struct image_args args; 251 struct vmspace *oldvmspace; 252 int error; 253 254 error = pre_execve(td, &oldvmspace); 255 if (error != 0) 256 return (error); 257 error = exec_copyin_args(&args, NULL, UIO_SYSSPACE, 258 uap->argv, uap->envv); 259 if (error == 0) { 260 args.fd = uap->fd; 261 error = kern_execve(td, &args, NULL, oldvmspace); 262 } 263 post_execve(td, error, oldvmspace); 264 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 265 return (error); 266 } 267 268 #ifndef _SYS_SYSPROTO_H_ 269 struct __mac_execve_args { 270 char *fname; 271 char **argv; 272 char **envv; 273 struct mac *mac_p; 274 }; 275 #endif 276 277 int 278 sys___mac_execve(struct thread *td, struct __mac_execve_args *uap) 279 { 280 #ifdef MAC 281 struct image_args args; 282 struct vmspace *oldvmspace; 283 int error; 284 285 error = pre_execve(td, &oldvmspace); 286 if (error != 0) 287 return (error); 288 error = exec_copyin_args(&args, uap->fname, UIO_USERSPACE, 289 uap->argv, uap->envv); 290 if (error == 0) 291 error = kern_execve(td, &args, uap->mac_p, oldvmspace); 292 post_execve(td, error, oldvmspace); 293 AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td); 294 return (error); 295 #else 296 return (ENOSYS); 297 #endif 298 } 299 300 int 301 pre_execve(struct thread *td, struct vmspace **oldvmspace) 302 { 303 struct proc *p; 304 int error; 305 306 KASSERT(td == curthread, ("non-current thread %p", td)); 307 error = 0; 308 p = td->td_proc; 309 if ((p->p_flag & P_HADTHREADS) != 0) { 310 PROC_LOCK(p); 311 if (thread_single(p, SINGLE_BOUNDARY) != 0) 312 error = ERESTART; 313 PROC_UNLOCK(p); 314 } 315 KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0, 316 ("nested execve")); 317 *oldvmspace = p->p_vmspace; 318 return (error); 319 } 320 321 void 322 post_execve(struct thread *td, int error, struct vmspace *oldvmspace) 323 { 324 struct proc *p; 325 326 KASSERT(td == curthread, ("non-current thread %p", td)); 327 p = td->td_proc; 328 if ((p->p_flag & P_HADTHREADS) != 0) { 329 PROC_LOCK(p); 330 /* 331 * If success, we upgrade to SINGLE_EXIT state to 332 * force other threads to suicide. 333 */ 334 if (error == EJUSTRETURN) 335 thread_single(p, SINGLE_EXIT); 336 else 337 thread_single_end(p, SINGLE_BOUNDARY); 338 PROC_UNLOCK(p); 339 } 340 exec_cleanup(td, oldvmspace); 341 } 342 343 /* 344 * kern_execve() has the astonishing property of not always returning to 345 * the caller. If sufficiently bad things happen during the call to 346 * do_execve(), it can end up calling exit1(); as a result, callers must 347 * avoid doing anything which they might need to undo (e.g., allocating 348 * memory). 349 */ 350 int 351 kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 352 struct vmspace *oldvmspace) 353 { 354 355 AUDIT_ARG_ARGV(args->begin_argv, args->argc, 356 exec_args_get_begin_envv(args) - args->begin_argv); 357 AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc, 358 args->endp - exec_args_get_begin_envv(args)); 359 return (do_execve(td, args, mac_p, oldvmspace)); 360 } 361 362 static void 363 execve_nosetid(struct image_params *imgp) 364 { 365 imgp->credential_setid = false; 366 if (imgp->newcred != NULL) { 367 crfree(imgp->newcred); 368 imgp->newcred = NULL; 369 } 370 } 371 372 /* 373 * In-kernel implementation of execve(). All arguments are assumed to be 374 * userspace pointers from the passed thread. 375 */ 376 static int 377 do_execve(struct thread *td, struct image_args *args, struct mac *mac_p, 378 struct vmspace *oldvmspace) 379 { 380 struct proc *p = td->td_proc; 381 struct nameidata nd; 382 struct ucred *oldcred; 383 struct uidinfo *euip = NULL; 384 uintptr_t stack_base; 385 struct image_params image_params, *imgp; 386 struct vattr attr; 387 int (*img_first)(struct image_params *); 388 struct pargs *oldargs = NULL, *newargs = NULL; 389 struct sigacts *oldsigacts = NULL, *newsigacts = NULL; 390 #ifdef KTRACE 391 struct ktr_io_params *kiop; 392 #endif 393 struct vnode *oldtextvp, *newtextvp; 394 struct vnode *oldtextdvp, *newtextdvp; 395 char *oldbinname, *newbinname; 396 bool credential_changing; 397 #ifdef MAC 398 struct label *interpvplabel = NULL; 399 bool will_transition; 400 #endif 401 #ifdef HWPMC_HOOKS 402 struct pmckern_procexec pe; 403 #endif 404 int error, i, orig_osrel; 405 uint32_t orig_fctl0; 406 size_t freepath_size; 407 static const char fexecv_proc_title[] = "(fexecv)"; 408 409 imgp = &image_params; 410 oldtextvp = oldtextdvp = NULL; 411 newtextvp = newtextdvp = NULL; 412 newbinname = oldbinname = NULL; 413 #ifdef KTRACE 414 kiop = NULL; 415 #endif 416 417 /* 418 * Lock the process and set the P_INEXEC flag to indicate that 419 * it should be left alone until we're done here. This is 420 * necessary to avoid race conditions - e.g. in ptrace() - 421 * that might allow a local user to illicitly obtain elevated 422 * privileges. 423 */ 424 PROC_LOCK(p); 425 KASSERT((p->p_flag & P_INEXEC) == 0, 426 ("%s(): process already has P_INEXEC flag", __func__)); 427 p->p_flag |= P_INEXEC; 428 PROC_UNLOCK(p); 429 430 /* 431 * Initialize part of the common data 432 */ 433 bzero(imgp, sizeof(*imgp)); 434 imgp->proc = p; 435 imgp->attr = &attr; 436 imgp->args = args; 437 oldcred = p->p_ucred; 438 orig_osrel = p->p_osrel; 439 orig_fctl0 = p->p_fctl0; 440 441 #ifdef MAC 442 error = mac_execve_enter(imgp, mac_p); 443 if (error) 444 goto exec_fail; 445 #endif 446 447 SDT_PROBE1(proc, , , exec, args->fname); 448 449 interpret: 450 if (args->fname != NULL) { 451 #ifdef CAPABILITY_MODE 452 /* 453 * While capability mode can't reach this point via direct 454 * path arguments to execve(), we also don't allow 455 * interpreters to be used in capability mode (for now). 456 * Catch indirect lookups and return a permissions error. 457 */ 458 if (IN_CAPABILITY_MODE(td)) { 459 error = ECAPMODE; 460 goto exec_fail; 461 } 462 #endif 463 464 /* 465 * Translate the file name. namei() returns a vnode 466 * pointer in ni_vp among other things. 467 */ 468 NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW | 469 SAVENAME | AUDITVNODE1 | WANTPARENT, UIO_SYSSPACE, 470 args->fname, td); 471 472 error = namei(&nd); 473 if (error) 474 goto exec_fail; 475 476 newtextvp = nd.ni_vp; 477 newtextdvp = nd.ni_dvp; 478 nd.ni_dvp = NULL; 479 newbinname = malloc(nd.ni_cnd.cn_namelen + 1, M_PARGS, 480 M_WAITOK); 481 memcpy(newbinname, nd.ni_cnd.cn_nameptr, nd.ni_cnd.cn_namelen); 482 newbinname[nd.ni_cnd.cn_namelen] = '\0'; 483 imgp->vp = newtextvp; 484 485 /* 486 * Do the best to calculate the full path to the image file. 487 */ 488 if (args->fname[0] == '/') { 489 imgp->execpath = args->fname; 490 } else { 491 VOP_UNLOCK(imgp->vp); 492 freepath_size = MAXPATHLEN; 493 if (vn_fullpath_hardlink(newtextvp, newtextdvp, 494 newbinname, nd.ni_cnd.cn_namelen, &imgp->execpath, 495 &imgp->freepath, &freepath_size) != 0) 496 imgp->execpath = args->fname; 497 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 498 } 499 } else { 500 AUDIT_ARG_FD(args->fd); 501 502 /* 503 * If the descriptors was not opened with O_PATH, then 504 * we require that it was opened with O_EXEC or 505 * O_RDONLY. In either case, exec_check_permissions() 506 * below checks _current_ file access mode regardless 507 * of the permissions additionally checked at the 508 * open(2). 509 */ 510 error = fgetvp_exec(td, args->fd, &cap_fexecve_rights, 511 &newtextvp); 512 if (error != 0) 513 goto exec_fail; 514 515 if (vn_fullpath(newtextvp, &imgp->execpath, 516 &imgp->freepath) != 0) 517 imgp->execpath = args->fname; 518 vn_lock(newtextvp, LK_SHARED | LK_RETRY); 519 AUDIT_ARG_VNODE1(newtextvp); 520 imgp->vp = newtextvp; 521 } 522 523 /* 524 * Check file permissions. Also 'opens' file and sets its vnode to 525 * text mode. 526 */ 527 error = exec_check_permissions(imgp); 528 if (error) 529 goto exec_fail_dealloc; 530 531 imgp->object = imgp->vp->v_object; 532 if (imgp->object != NULL) 533 vm_object_reference(imgp->object); 534 535 error = exec_map_first_page(imgp); 536 if (error) 537 goto exec_fail_dealloc; 538 539 imgp->proc->p_osrel = 0; 540 imgp->proc->p_fctl0 = 0; 541 542 /* 543 * Implement image setuid/setgid. 544 * 545 * Determine new credentials before attempting image activators 546 * so that it can be used by process_exec handlers to determine 547 * credential/setid changes. 548 * 549 * Don't honor setuid/setgid if the filesystem prohibits it or if 550 * the process is being traced. 551 * 552 * We disable setuid/setgid/etc in capability mode on the basis 553 * that most setugid applications are not written with that 554 * environment in mind, and will therefore almost certainly operate 555 * incorrectly. In principle there's no reason that setugid 556 * applications might not be useful in capability mode, so we may want 557 * to reconsider this conservative design choice in the future. 558 * 559 * XXXMAC: For the time being, use NOSUID to also prohibit 560 * transitions on the file system. 561 */ 562 credential_changing = false; 563 credential_changing |= (attr.va_mode & S_ISUID) && 564 oldcred->cr_uid != attr.va_uid; 565 credential_changing |= (attr.va_mode & S_ISGID) && 566 oldcred->cr_gid != attr.va_gid; 567 #ifdef MAC 568 will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp, 569 interpvplabel, imgp) != 0; 570 credential_changing |= will_transition; 571 #endif 572 573 /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */ 574 if (credential_changing) 575 imgp->proc->p_pdeathsig = 0; 576 577 if (credential_changing && 578 #ifdef CAPABILITY_MODE 579 ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) && 580 #endif 581 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 582 (p->p_flag & P_TRACED) == 0) { 583 imgp->credential_setid = true; 584 VOP_UNLOCK(imgp->vp); 585 imgp->newcred = crdup(oldcred); 586 if (attr.va_mode & S_ISUID) { 587 euip = uifind(attr.va_uid); 588 change_euid(imgp->newcred, euip); 589 } 590 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 591 if (attr.va_mode & S_ISGID) 592 change_egid(imgp->newcred, attr.va_gid); 593 /* 594 * Implement correct POSIX saved-id behavior. 595 * 596 * XXXMAC: Note that the current logic will save the 597 * uid and gid if a MAC domain transition occurs, even 598 * though maybe it shouldn't. 599 */ 600 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 601 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 602 } else { 603 /* 604 * Implement correct POSIX saved-id behavior. 605 * 606 * XXX: It's not clear that the existing behavior is 607 * POSIX-compliant. A number of sources indicate that the 608 * saved uid/gid should only be updated if the new ruid is 609 * not equal to the old ruid, or the new euid is not equal 610 * to the old euid and the new euid is not equal to the old 611 * ruid. The FreeBSD code always updates the saved uid/gid. 612 * Also, this code uses the new (replaced) euid and egid as 613 * the source, which may or may not be the right ones to use. 614 */ 615 if (oldcred->cr_svuid != oldcred->cr_uid || 616 oldcred->cr_svgid != oldcred->cr_gid) { 617 VOP_UNLOCK(imgp->vp); 618 imgp->newcred = crdup(oldcred); 619 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 620 change_svuid(imgp->newcred, imgp->newcred->cr_uid); 621 change_svgid(imgp->newcred, imgp->newcred->cr_gid); 622 } 623 } 624 /* The new credentials are installed into the process later. */ 625 626 /* 627 * If the current process has a special image activator it 628 * wants to try first, call it. For example, emulating shell 629 * scripts differently. 630 */ 631 error = -1; 632 if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) 633 error = img_first(imgp); 634 635 /* 636 * Loop through the list of image activators, calling each one. 637 * An activator returns -1 if there is no match, 0 on success, 638 * and an error otherwise. 639 */ 640 for (i = 0; error == -1 && execsw[i]; ++i) { 641 if (execsw[i]->ex_imgact == NULL || 642 execsw[i]->ex_imgact == img_first) { 643 continue; 644 } 645 error = (*execsw[i]->ex_imgact)(imgp); 646 } 647 648 if (error) { 649 if (error == -1) 650 error = ENOEXEC; 651 goto exec_fail_dealloc; 652 } 653 654 /* 655 * Special interpreter operation, cleanup and loop up to try to 656 * activate the interpreter. 657 */ 658 if (imgp->interpreted) { 659 exec_unmap_first_page(imgp); 660 /* 661 * The text reference needs to be removed for scripts. 662 * There is a short period before we determine that 663 * something is a script where text reference is active. 664 * The vnode lock is held over this entire period 665 * so nothing should illegitimately be blocked. 666 */ 667 MPASS(imgp->textset); 668 VOP_UNSET_TEXT_CHECKED(newtextvp); 669 imgp->textset = false; 670 /* free name buffer and old vnode */ 671 #ifdef MAC 672 mac_execve_interpreter_enter(newtextvp, &interpvplabel); 673 #endif 674 if (imgp->opened) { 675 VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td); 676 imgp->opened = false; 677 } 678 vput(newtextvp); 679 imgp->vp = newtextvp = NULL; 680 if (args->fname != NULL) { 681 if (newtextdvp != NULL) { 682 vrele(newtextdvp); 683 newtextdvp = NULL; 684 } 685 NDFREE(&nd, NDF_ONLY_PNBUF); 686 free(newbinname, M_PARGS); 687 newbinname = NULL; 688 } 689 vm_object_deallocate(imgp->object); 690 imgp->object = NULL; 691 execve_nosetid(imgp); 692 imgp->execpath = NULL; 693 free(imgp->freepath, M_TEMP); 694 imgp->freepath = NULL; 695 /* set new name to that of the interpreter */ 696 args->fname = imgp->interpreter_name; 697 goto interpret; 698 } 699 700 /* 701 * NB: We unlock the vnode here because it is believed that none 702 * of the sv_copyout_strings/sv_fixup operations require the vnode. 703 */ 704 VOP_UNLOCK(imgp->vp); 705 706 if (disallow_high_osrel && 707 P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) { 708 error = ENOEXEC; 709 uprintf("Osrel %d for image %s too high\n", p->p_osrel, 710 imgp->execpath != NULL ? imgp->execpath : "<unresolved>"); 711 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 712 goto exec_fail_dealloc; 713 } 714 715 /* ABI enforces the use of Capsicum. Switch into capabilities mode. */ 716 if (SV_PROC_FLAG(p, SV_CAPSICUM)) 717 sys_cap_enter(td, NULL); 718 719 /* 720 * Copy out strings (args and env) and initialize stack base. 721 */ 722 error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base); 723 if (error != 0) { 724 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 725 goto exec_fail_dealloc; 726 } 727 728 /* 729 * Stack setup. 730 */ 731 error = (*p->p_sysent->sv_fixup)(&stack_base, imgp); 732 if (error != 0) { 733 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 734 goto exec_fail_dealloc; 735 } 736 737 if (args->fdp != NULL) { 738 /* Install a brand new file descriptor table. */ 739 fdinstall_remapped(td, args->fdp); 740 args->fdp = NULL; 741 } else { 742 /* 743 * Keep on using the existing file descriptor table. For 744 * security and other reasons, the file descriptor table 745 * cannot be shared after an exec. 746 */ 747 fdunshare(td); 748 pdunshare(td); 749 /* close files on exec */ 750 fdcloseexec(td); 751 } 752 753 /* 754 * Malloc things before we need locks. 755 */ 756 i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv; 757 /* Cache arguments if they fit inside our allowance */ 758 if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { 759 newargs = pargs_alloc(i); 760 bcopy(imgp->args->begin_argv, newargs->ar_args, i); 761 } 762 763 /* 764 * For security and other reasons, signal handlers cannot 765 * be shared after an exec. The new process gets a copy of the old 766 * handlers. In execsigs(), the new process will have its signals 767 * reset. 768 */ 769 if (sigacts_shared(p->p_sigacts)) { 770 oldsigacts = p->p_sigacts; 771 newsigacts = sigacts_alloc(); 772 sigacts_copy(newsigacts, oldsigacts); 773 } 774 775 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 776 777 PROC_LOCK(p); 778 if (oldsigacts) 779 p->p_sigacts = newsigacts; 780 /* Stop profiling */ 781 stopprofclock(p); 782 783 /* reset caught signals */ 784 execsigs(p); 785 786 /* name this process - nameiexec(p, ndp) */ 787 bzero(p->p_comm, sizeof(p->p_comm)); 788 if (args->fname) 789 bcopy(nd.ni_cnd.cn_nameptr, p->p_comm, 790 min(nd.ni_cnd.cn_namelen, MAXCOMLEN)); 791 else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0) 792 bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title)); 793 bcopy(p->p_comm, td->td_name, sizeof(td->td_name)); 794 #ifdef KTR 795 sched_clear_tdname(td); 796 #endif 797 798 /* 799 * mark as execed, wakeup the process that vforked (if any) and tell 800 * it that it now has its own resources back 801 */ 802 p->p_flag |= P_EXEC; 803 if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0) 804 p->p_flag2 &= ~P2_NOTRACE; 805 if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0) 806 p->p_flag2 &= ~P2_STKGAP_DISABLE; 807 if (p->p_flag & P_PPWAIT) { 808 p->p_flag &= ~(P_PPWAIT | P_PPTRACE); 809 cv_broadcast(&p->p_pwait); 810 /* STOPs are no longer ignored, arrange for AST */ 811 signotify(td); 812 } 813 814 if ((imgp->sysent->sv_setid_allowed != NULL && 815 !(*imgp->sysent->sv_setid_allowed)(td, imgp)) || 816 (p->p_flag2 & P2_NO_NEW_PRIVS) != 0) 817 execve_nosetid(imgp); 818 819 /* 820 * Implement image setuid/setgid installation. 821 */ 822 if (imgp->credential_setid) { 823 /* 824 * Turn off syscall tracing for set-id programs, except for 825 * root. Record any set-id flags first to make sure that 826 * we do not regain any tracing during a possible block. 827 */ 828 setsugid(p); 829 #ifdef KTRACE 830 kiop = ktrprocexec(p); 831 #endif 832 /* 833 * Close any file descriptors 0..2 that reference procfs, 834 * then make sure file descriptors 0..2 are in use. 835 * 836 * Both fdsetugidsafety() and fdcheckstd() may call functions 837 * taking sleepable locks, so temporarily drop our locks. 838 */ 839 PROC_UNLOCK(p); 840 VOP_UNLOCK(imgp->vp); 841 fdsetugidsafety(td); 842 error = fdcheckstd(td); 843 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 844 if (error != 0) 845 goto exec_fail_dealloc; 846 PROC_LOCK(p); 847 #ifdef MAC 848 if (will_transition) { 849 mac_vnode_execve_transition(oldcred, imgp->newcred, 850 imgp->vp, interpvplabel, imgp); 851 } 852 #endif 853 } else { 854 if (oldcred->cr_uid == oldcred->cr_ruid && 855 oldcred->cr_gid == oldcred->cr_rgid) 856 p->p_flag &= ~P_SUGID; 857 } 858 /* 859 * Set the new credentials. 860 */ 861 if (imgp->newcred != NULL) { 862 proc_set_cred(p, imgp->newcred); 863 crfree(oldcred); 864 oldcred = NULL; 865 } 866 867 /* 868 * Store the vp for use in kern.proc.pathname. This vnode was 869 * referenced by namei() or by fexecve variant of fname handling. 870 */ 871 oldtextvp = p->p_textvp; 872 p->p_textvp = newtextvp; 873 oldtextdvp = p->p_textdvp; 874 p->p_textdvp = newtextdvp; 875 newtextdvp = NULL; 876 oldbinname = p->p_binname; 877 p->p_binname = newbinname; 878 newbinname = NULL; 879 880 #ifdef KDTRACE_HOOKS 881 /* 882 * Tell the DTrace fasttrap provider about the exec if it 883 * has declared an interest. 884 */ 885 if (dtrace_fasttrap_exec) 886 dtrace_fasttrap_exec(p); 887 #endif 888 889 /* 890 * Notify others that we exec'd, and clear the P_INEXEC flag 891 * as we're now a bona fide freshly-execed process. 892 */ 893 KNOTE_LOCKED(p->p_klist, NOTE_EXEC); 894 p->p_flag &= ~P_INEXEC; 895 896 /* clear "fork but no exec" flag, as we _are_ execing */ 897 p->p_acflag &= ~AFORK; 898 899 /* 900 * Free any previous argument cache and replace it with 901 * the new argument cache, if any. 902 */ 903 oldargs = p->p_args; 904 p->p_args = newargs; 905 newargs = NULL; 906 907 PROC_UNLOCK(p); 908 909 #ifdef HWPMC_HOOKS 910 /* 911 * Check if system-wide sampling is in effect or if the 912 * current process is using PMCs. If so, do exec() time 913 * processing. This processing needs to happen AFTER the 914 * P_INEXEC flag is cleared. 915 */ 916 if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) { 917 VOP_UNLOCK(imgp->vp); 918 pe.pm_credentialschanged = credential_changing; 919 pe.pm_entryaddr = imgp->entry_addr; 920 921 PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe); 922 vn_lock(imgp->vp, LK_SHARED | LK_RETRY); 923 } 924 #endif 925 926 /* Set values passed into the program in registers. */ 927 (*p->p_sysent->sv_setregs)(td, imgp, stack_base); 928 929 VOP_MMAPPED(imgp->vp); 930 931 SDT_PROBE1(proc, , , exec__success, args->fname); 932 933 exec_fail_dealloc: 934 if (error != 0) { 935 p->p_osrel = orig_osrel; 936 p->p_fctl0 = orig_fctl0; 937 } 938 939 if (imgp->firstpage != NULL) 940 exec_unmap_first_page(imgp); 941 942 if (imgp->vp != NULL) { 943 if (imgp->opened) 944 VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td); 945 if (imgp->textset) 946 VOP_UNSET_TEXT_CHECKED(imgp->vp); 947 if (error != 0) 948 vput(imgp->vp); 949 else 950 VOP_UNLOCK(imgp->vp); 951 if (args->fname != NULL) 952 NDFREE(&nd, NDF_ONLY_PNBUF); 953 if (newtextdvp != NULL) 954 vrele(newtextdvp); 955 free(newbinname, M_PARGS); 956 } 957 958 if (imgp->object != NULL) 959 vm_object_deallocate(imgp->object); 960 961 free(imgp->freepath, M_TEMP); 962 963 if (error == 0) { 964 if (p->p_ptevents & PTRACE_EXEC) { 965 PROC_LOCK(p); 966 if (p->p_ptevents & PTRACE_EXEC) 967 td->td_dbgflags |= TDB_EXEC; 968 PROC_UNLOCK(p); 969 } 970 } else { 971 exec_fail: 972 /* we're done here, clear P_INEXEC */ 973 PROC_LOCK(p); 974 p->p_flag &= ~P_INEXEC; 975 PROC_UNLOCK(p); 976 977 SDT_PROBE1(proc, , , exec__failure, error); 978 } 979 980 if (imgp->newcred != NULL && oldcred != NULL) 981 crfree(imgp->newcred); 982 983 #ifdef MAC 984 mac_execve_exit(imgp); 985 mac_execve_interpreter_exit(interpvplabel); 986 #endif 987 exec_free_args(args); 988 989 /* 990 * Handle deferred decrement of ref counts. 991 */ 992 if (oldtextvp != NULL) 993 vrele(oldtextvp); 994 if (oldtextdvp != NULL) 995 vrele(oldtextdvp); 996 free(oldbinname, M_PARGS); 997 #ifdef KTRACE 998 ktr_io_params_free(kiop); 999 #endif 1000 pargs_drop(oldargs); 1001 pargs_drop(newargs); 1002 if (oldsigacts != NULL) 1003 sigacts_free(oldsigacts); 1004 if (euip != NULL) 1005 uifree(euip); 1006 1007 if (error && imgp->vmspace_destroyed) { 1008 /* sorry, no more process anymore. exit gracefully */ 1009 exec_cleanup(td, oldvmspace); 1010 exit1(td, 0, SIGABRT); 1011 /* NOT REACHED */ 1012 } 1013 1014 #ifdef KTRACE 1015 if (error == 0) 1016 ktrprocctor(p); 1017 #endif 1018 1019 /* 1020 * We don't want cpu_set_syscall_retval() to overwrite any of 1021 * the register values put in place by exec_setregs(). 1022 * Implementations of cpu_set_syscall_retval() will leave 1023 * registers unmodified when returning EJUSTRETURN. 1024 */ 1025 return (error == 0 ? EJUSTRETURN : error); 1026 } 1027 1028 void 1029 exec_cleanup(struct thread *td, struct vmspace *oldvmspace) 1030 { 1031 if ((td->td_pflags & TDP_EXECVMSPC) != 0) { 1032 KASSERT(td->td_proc->p_vmspace != oldvmspace, 1033 ("oldvmspace still used")); 1034 vmspace_free(oldvmspace); 1035 td->td_pflags &= ~TDP_EXECVMSPC; 1036 } 1037 } 1038 1039 int 1040 exec_map_first_page(struct image_params *imgp) 1041 { 1042 vm_object_t object; 1043 vm_page_t m; 1044 int error; 1045 1046 if (imgp->firstpage != NULL) 1047 exec_unmap_first_page(imgp); 1048 1049 object = imgp->vp->v_object; 1050 if (object == NULL) 1051 return (EACCES); 1052 #if VM_NRESERVLEVEL > 0 1053 if ((object->flags & OBJ_COLORED) == 0) { 1054 VM_OBJECT_WLOCK(object); 1055 vm_object_color(object, 0); 1056 VM_OBJECT_WUNLOCK(object); 1057 } 1058 #endif 1059 error = vm_page_grab_valid_unlocked(&m, object, 0, 1060 VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) | 1061 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED); 1062 1063 if (error != VM_PAGER_OK) 1064 return (EIO); 1065 imgp->firstpage = sf_buf_alloc(m, 0); 1066 imgp->image_header = (char *)sf_buf_kva(imgp->firstpage); 1067 1068 return (0); 1069 } 1070 1071 void 1072 exec_unmap_first_page(struct image_params *imgp) 1073 { 1074 vm_page_t m; 1075 1076 if (imgp->firstpage != NULL) { 1077 m = sf_buf_page(imgp->firstpage); 1078 sf_buf_free(imgp->firstpage); 1079 imgp->firstpage = NULL; 1080 vm_page_unwire(m, PQ_ACTIVE); 1081 } 1082 } 1083 1084 void 1085 exec_onexec_old(struct thread *td) 1086 { 1087 sigfastblock_clear(td); 1088 umtx_exec(td->td_proc); 1089 } 1090 1091 /* 1092 * This is an optimization which removes the unmanaged shared page 1093 * mapping. In combination with pmap_remove_pages(), which cleans all 1094 * managed mappings in the process' vmspace pmap, no work will be left 1095 * for pmap_remove(min, max). 1096 */ 1097 void 1098 exec_free_abi_mappings(struct proc *p) 1099 { 1100 struct vmspace *vmspace; 1101 struct sysentvec *sv; 1102 1103 vmspace = p->p_vmspace; 1104 if (refcount_load(&vmspace->vm_refcnt) != 1) 1105 return; 1106 1107 sv = p->p_sysent; 1108 if (sv->sv_shared_page_obj == NULL) 1109 return; 1110 1111 pmap_remove(vmspace_pmap(vmspace), sv->sv_shared_page_base, 1112 sv->sv_shared_page_base + sv->sv_shared_page_len); 1113 } 1114 1115 /* 1116 * Destroy old address space, and allocate a new stack. 1117 * The new stack is only sgrowsiz large because it is grown 1118 * automatically on a page fault. 1119 */ 1120 int 1121 exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv) 1122 { 1123 int error; 1124 struct proc *p = imgp->proc; 1125 struct vmspace *vmspace = p->p_vmspace; 1126 struct thread *td = curthread; 1127 vm_object_t obj; 1128 struct rlimit rlim_stack; 1129 vm_offset_t sv_minuser, stack_addr; 1130 vm_map_t map; 1131 vm_prot_t stack_prot; 1132 u_long ssiz; 1133 1134 imgp->vmspace_destroyed = true; 1135 imgp->sysent = sv; 1136 1137 if (p->p_sysent->sv_onexec_old != NULL) 1138 p->p_sysent->sv_onexec_old(td); 1139 itimers_exec(p); 1140 if (sv->sv_onexec != NULL) 1141 sv->sv_onexec(p, imgp); 1142 1143 EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp); 1144 1145 /* 1146 * Blow away entire process VM, if address space not shared, 1147 * otherwise, create a new VM space so that other threads are 1148 * not disrupted 1149 */ 1150 map = &vmspace->vm_map; 1151 if (map_at_zero) 1152 sv_minuser = sv->sv_minuser; 1153 else 1154 sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE); 1155 if (refcount_load(&vmspace->vm_refcnt) == 1 && 1156 vm_map_min(map) == sv_minuser && 1157 vm_map_max(map) == sv->sv_maxuser && 1158 cpu_exec_vmspace_reuse(p, map)) { 1159 exec_free_abi_mappings(p); 1160 shmexit(vmspace); 1161 pmap_remove_pages(vmspace_pmap(vmspace)); 1162 vm_map_remove(map, vm_map_min(map), vm_map_max(map)); 1163 /* 1164 * An exec terminates mlockall(MCL_FUTURE). 1165 * ASLR and W^X states must be re-evaluated. 1166 */ 1167 vm_map_lock(map); 1168 vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR | 1169 MAP_ASLR_IGNSTART | MAP_WXORX); 1170 vm_map_unlock(map); 1171 } else { 1172 error = vmspace_exec(p, sv_minuser, sv->sv_maxuser); 1173 if (error) 1174 return (error); 1175 vmspace = p->p_vmspace; 1176 map = &vmspace->vm_map; 1177 } 1178 map->flags |= imgp->map_flags; 1179 1180 /* Map a shared page */ 1181 obj = sv->sv_shared_page_obj; 1182 if (obj != NULL) { 1183 vm_object_reference(obj); 1184 error = vm_map_fixed(map, obj, 0, 1185 sv->sv_shared_page_base, sv->sv_shared_page_len, 1186 VM_PROT_READ | VM_PROT_EXECUTE, 1187 VM_PROT_READ | VM_PROT_EXECUTE, 1188 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 1189 if (error != KERN_SUCCESS) { 1190 vm_object_deallocate(obj); 1191 return (vm_mmap_to_errno(error)); 1192 } 1193 } 1194 1195 /* Allocate a new stack */ 1196 if (imgp->stack_sz != 0) { 1197 ssiz = trunc_page(imgp->stack_sz); 1198 PROC_LOCK(p); 1199 lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack); 1200 PROC_UNLOCK(p); 1201 if (ssiz > rlim_stack.rlim_max) 1202 ssiz = rlim_stack.rlim_max; 1203 if (ssiz > rlim_stack.rlim_cur) { 1204 rlim_stack.rlim_cur = ssiz; 1205 kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack); 1206 } 1207 } else if (sv->sv_maxssiz != NULL) { 1208 ssiz = *sv->sv_maxssiz; 1209 } else { 1210 ssiz = maxssiz; 1211 } 1212 imgp->eff_stack_sz = lim_cur(curthread, RLIMIT_STACK); 1213 if (ssiz < imgp->eff_stack_sz) 1214 imgp->eff_stack_sz = ssiz; 1215 stack_addr = sv->sv_usrstack - ssiz; 1216 stack_prot = obj != NULL && imgp->stack_prot != 0 ? 1217 imgp->stack_prot : sv->sv_stackprot; 1218 error = vm_map_stack(map, stack_addr, (vm_size_t)ssiz, stack_prot, 1219 VM_PROT_ALL, MAP_STACK_GROWS_DOWN); 1220 if (error != KERN_SUCCESS) { 1221 uprintf("exec_new_vmspace: mapping stack size %#jx prot %#x " 1222 "failed mach error %d errno %d\n", (uintmax_t)ssiz, 1223 stack_prot, error, vm_mmap_to_errno(error)); 1224 return (vm_mmap_to_errno(error)); 1225 } 1226 1227 /* 1228 * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they 1229 * are still used to enforce the stack rlimit on the process stack. 1230 */ 1231 vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; 1232 vmspace->vm_maxsaddr = (char *)stack_addr; 1233 1234 return (0); 1235 } 1236 1237 /* 1238 * Copy out argument and environment strings from the old process address 1239 * space into the temporary string buffer. 1240 */ 1241 int 1242 exec_copyin_args(struct image_args *args, const char *fname, 1243 enum uio_seg segflg, char **argv, char **envv) 1244 { 1245 u_long arg, env; 1246 int error; 1247 1248 bzero(args, sizeof(*args)); 1249 if (argv == NULL) 1250 return (EFAULT); 1251 1252 /* 1253 * Allocate demand-paged memory for the file name, argument, and 1254 * environment strings. 1255 */ 1256 error = exec_alloc_args(args); 1257 if (error != 0) 1258 return (error); 1259 1260 /* 1261 * Copy the file name. 1262 */ 1263 error = exec_args_add_fname(args, fname, segflg); 1264 if (error != 0) 1265 goto err_exit; 1266 1267 /* 1268 * extract arguments first 1269 */ 1270 for (;;) { 1271 error = fueword(argv++, &arg); 1272 if (error == -1) { 1273 error = EFAULT; 1274 goto err_exit; 1275 } 1276 if (arg == 0) 1277 break; 1278 error = exec_args_add_arg(args, (char *)(uintptr_t)arg, 1279 UIO_USERSPACE); 1280 if (error != 0) 1281 goto err_exit; 1282 } 1283 1284 /* 1285 * extract environment strings 1286 */ 1287 if (envv) { 1288 for (;;) { 1289 error = fueword(envv++, &env); 1290 if (error == -1) { 1291 error = EFAULT; 1292 goto err_exit; 1293 } 1294 if (env == 0) 1295 break; 1296 error = exec_args_add_env(args, 1297 (char *)(uintptr_t)env, UIO_USERSPACE); 1298 if (error != 0) 1299 goto err_exit; 1300 } 1301 } 1302 1303 return (0); 1304 1305 err_exit: 1306 exec_free_args(args); 1307 return (error); 1308 } 1309 1310 int 1311 exec_copyin_data_fds(struct thread *td, struct image_args *args, 1312 const void *data, size_t datalen, const int *fds, size_t fdslen) 1313 { 1314 struct filedesc *ofdp; 1315 const char *p; 1316 int *kfds; 1317 int error; 1318 1319 memset(args, '\0', sizeof(*args)); 1320 ofdp = td->td_proc->p_fd; 1321 if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles) 1322 return (E2BIG); 1323 error = exec_alloc_args(args); 1324 if (error != 0) 1325 return (error); 1326 1327 args->begin_argv = args->buf; 1328 args->stringspace = ARG_MAX; 1329 1330 if (datalen > 0) { 1331 /* 1332 * Argument buffer has been provided. Copy it into the 1333 * kernel as a single string and add a terminating null 1334 * byte. 1335 */ 1336 error = copyin(data, args->begin_argv, datalen); 1337 if (error != 0) 1338 goto err_exit; 1339 args->begin_argv[datalen] = '\0'; 1340 args->endp = args->begin_argv + datalen + 1; 1341 args->stringspace -= datalen + 1; 1342 1343 /* 1344 * Traditional argument counting. Count the number of 1345 * null bytes. 1346 */ 1347 for (p = args->begin_argv; p < args->endp; ++p) 1348 if (*p == '\0') 1349 ++args->argc; 1350 } else { 1351 /* No argument buffer provided. */ 1352 args->endp = args->begin_argv; 1353 } 1354 1355 /* Create new file descriptor table. */ 1356 kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK); 1357 error = copyin(fds, kfds, fdslen * sizeof(int)); 1358 if (error != 0) { 1359 free(kfds, M_TEMP); 1360 goto err_exit; 1361 } 1362 error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp); 1363 free(kfds, M_TEMP); 1364 if (error != 0) 1365 goto err_exit; 1366 1367 return (0); 1368 err_exit: 1369 exec_free_args(args); 1370 return (error); 1371 } 1372 1373 struct exec_args_kva { 1374 vm_offset_t addr; 1375 u_int gen; 1376 SLIST_ENTRY(exec_args_kva) next; 1377 }; 1378 1379 DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva); 1380 1381 static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist; 1382 static struct mtx exec_args_kva_mtx; 1383 static u_int exec_args_gen; 1384 1385 static void 1386 exec_prealloc_args_kva(void *arg __unused) 1387 { 1388 struct exec_args_kva *argkva; 1389 u_int i; 1390 1391 SLIST_INIT(&exec_args_kva_freelist); 1392 mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF); 1393 for (i = 0; i < exec_map_entries; i++) { 1394 argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK); 1395 argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size); 1396 argkva->gen = exec_args_gen; 1397 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1398 } 1399 } 1400 SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL); 1401 1402 static vm_offset_t 1403 exec_alloc_args_kva(void **cookie) 1404 { 1405 struct exec_args_kva *argkva; 1406 1407 argkva = (void *)atomic_readandclear_ptr( 1408 (uintptr_t *)DPCPU_PTR(exec_args_kva)); 1409 if (argkva == NULL) { 1410 mtx_lock(&exec_args_kva_mtx); 1411 while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL) 1412 (void)mtx_sleep(&exec_args_kva_freelist, 1413 &exec_args_kva_mtx, 0, "execkva", 0); 1414 SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next); 1415 mtx_unlock(&exec_args_kva_mtx); 1416 } 1417 kasan_mark((void *)argkva->addr, exec_map_entry_size, 1418 exec_map_entry_size, 0); 1419 *(struct exec_args_kva **)cookie = argkva; 1420 return (argkva->addr); 1421 } 1422 1423 static void 1424 exec_release_args_kva(struct exec_args_kva *argkva, u_int gen) 1425 { 1426 vm_offset_t base; 1427 1428 base = argkva->addr; 1429 kasan_mark((void *)argkva->addr, 0, exec_map_entry_size, 1430 KASAN_EXEC_ARGS_FREED); 1431 if (argkva->gen != gen) { 1432 (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size, 1433 MADV_FREE); 1434 argkva->gen = gen; 1435 } 1436 if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva), 1437 (uintptr_t)NULL, (uintptr_t)argkva)) { 1438 mtx_lock(&exec_args_kva_mtx); 1439 SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next); 1440 wakeup_one(&exec_args_kva_freelist); 1441 mtx_unlock(&exec_args_kva_mtx); 1442 } 1443 } 1444 1445 static void 1446 exec_free_args_kva(void *cookie) 1447 { 1448 1449 exec_release_args_kva(cookie, exec_args_gen); 1450 } 1451 1452 static void 1453 exec_args_kva_lowmem(void *arg __unused) 1454 { 1455 SLIST_HEAD(, exec_args_kva) head; 1456 struct exec_args_kva *argkva; 1457 u_int gen; 1458 int i; 1459 1460 gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1; 1461 1462 /* 1463 * Force an madvise of each KVA range. Any currently allocated ranges 1464 * will have MADV_FREE applied once they are freed. 1465 */ 1466 SLIST_INIT(&head); 1467 mtx_lock(&exec_args_kva_mtx); 1468 SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva); 1469 mtx_unlock(&exec_args_kva_mtx); 1470 while ((argkva = SLIST_FIRST(&head)) != NULL) { 1471 SLIST_REMOVE_HEAD(&head, next); 1472 exec_release_args_kva(argkva, gen); 1473 } 1474 1475 CPU_FOREACH(i) { 1476 argkva = (void *)atomic_readandclear_ptr( 1477 (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva)); 1478 if (argkva != NULL) 1479 exec_release_args_kva(argkva, gen); 1480 } 1481 } 1482 EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL, 1483 EVENTHANDLER_PRI_ANY); 1484 1485 /* 1486 * Allocate temporary demand-paged, zero-filled memory for the file name, 1487 * argument, and environment strings. 1488 */ 1489 int 1490 exec_alloc_args(struct image_args *args) 1491 { 1492 1493 args->buf = (char *)exec_alloc_args_kva(&args->bufkva); 1494 return (0); 1495 } 1496 1497 void 1498 exec_free_args(struct image_args *args) 1499 { 1500 1501 if (args->buf != NULL) { 1502 exec_free_args_kva(args->bufkva); 1503 args->buf = NULL; 1504 } 1505 if (args->fname_buf != NULL) { 1506 free(args->fname_buf, M_TEMP); 1507 args->fname_buf = NULL; 1508 } 1509 if (args->fdp != NULL) 1510 fdescfree_remapped(args->fdp); 1511 } 1512 1513 /* 1514 * A set to functions to fill struct image args. 1515 * 1516 * NOTE: exec_args_add_fname() must be called (possibly with a NULL 1517 * fname) before the other functions. All exec_args_add_arg() calls must 1518 * be made before any exec_args_add_env() calls. exec_args_adjust_args() 1519 * may be called any time after exec_args_add_fname(). 1520 * 1521 * exec_args_add_fname() - install path to be executed 1522 * exec_args_add_arg() - append an argument string 1523 * exec_args_add_env() - append an env string 1524 * exec_args_adjust_args() - adjust location of the argument list to 1525 * allow new arguments to be prepended 1526 */ 1527 int 1528 exec_args_add_fname(struct image_args *args, const char *fname, 1529 enum uio_seg segflg) 1530 { 1531 int error; 1532 size_t length; 1533 1534 KASSERT(args->fname == NULL, ("fname already appended")); 1535 KASSERT(args->endp == NULL, ("already appending to args")); 1536 1537 if (fname != NULL) { 1538 args->fname = args->buf; 1539 error = segflg == UIO_SYSSPACE ? 1540 copystr(fname, args->fname, PATH_MAX, &length) : 1541 copyinstr(fname, args->fname, PATH_MAX, &length); 1542 if (error != 0) 1543 return (error == ENAMETOOLONG ? E2BIG : error); 1544 } else 1545 length = 0; 1546 1547 /* Set up for _arg_*()/_env_*() */ 1548 args->endp = args->buf + length; 1549 /* begin_argv must be set and kept updated */ 1550 args->begin_argv = args->endp; 1551 KASSERT(exec_map_entry_size - length >= ARG_MAX, 1552 ("too little space remaining for arguments %zu < %zu", 1553 exec_map_entry_size - length, (size_t)ARG_MAX)); 1554 args->stringspace = ARG_MAX; 1555 1556 return (0); 1557 } 1558 1559 static int 1560 exec_args_add_str(struct image_args *args, const char *str, 1561 enum uio_seg segflg, int *countp) 1562 { 1563 int error; 1564 size_t length; 1565 1566 KASSERT(args->endp != NULL, ("endp not initialized")); 1567 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1568 1569 error = (segflg == UIO_SYSSPACE) ? 1570 copystr(str, args->endp, args->stringspace, &length) : 1571 copyinstr(str, args->endp, args->stringspace, &length); 1572 if (error != 0) 1573 return (error == ENAMETOOLONG ? E2BIG : error); 1574 args->stringspace -= length; 1575 args->endp += length; 1576 (*countp)++; 1577 1578 return (0); 1579 } 1580 1581 int 1582 exec_args_add_arg(struct image_args *args, const char *argp, 1583 enum uio_seg segflg) 1584 { 1585 1586 KASSERT(args->envc == 0, ("appending args after env")); 1587 1588 return (exec_args_add_str(args, argp, segflg, &args->argc)); 1589 } 1590 1591 int 1592 exec_args_add_env(struct image_args *args, const char *envp, 1593 enum uio_seg segflg) 1594 { 1595 1596 if (args->envc == 0) 1597 args->begin_envv = args->endp; 1598 1599 return (exec_args_add_str(args, envp, segflg, &args->envc)); 1600 } 1601 1602 int 1603 exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend) 1604 { 1605 ssize_t offset; 1606 1607 KASSERT(args->endp != NULL, ("endp not initialized")); 1608 KASSERT(args->begin_argv != NULL, ("begin_argp not initialized")); 1609 1610 offset = extend - consume; 1611 if (args->stringspace < offset) 1612 return (E2BIG); 1613 memmove(args->begin_argv + extend, args->begin_argv + consume, 1614 args->endp - args->begin_argv + consume); 1615 if (args->envc > 0) 1616 args->begin_envv += offset; 1617 args->endp += offset; 1618 args->stringspace -= offset; 1619 return (0); 1620 } 1621 1622 char * 1623 exec_args_get_begin_envv(struct image_args *args) 1624 { 1625 1626 KASSERT(args->endp != NULL, ("endp not initialized")); 1627 1628 if (args->envc > 0) 1629 return (args->begin_envv); 1630 return (args->endp); 1631 } 1632 1633 void 1634 exec_stackgap(struct image_params *imgp, uintptr_t *dp) 1635 { 1636 if (imgp->sysent->sv_stackgap == NULL || 1637 (imgp->proc->p_fctl0 & (NT_FREEBSD_FCTL_ASLR_DISABLE | 1638 NT_FREEBSD_FCTL_ASG_DISABLE)) != 0 || 1639 (imgp->map_flags & MAP_ASLR) == 0) 1640 return; 1641 imgp->sysent->sv_stackgap(imgp, dp); 1642 } 1643 1644 /* 1645 * Copy strings out to the new process address space, constructing new arg 1646 * and env vector tables. Return a pointer to the base so that it can be used 1647 * as the initial stack pointer. 1648 */ 1649 int 1650 exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base) 1651 { 1652 int argc, envc; 1653 char **vectp; 1654 char *stringp; 1655 uintptr_t destp, ustringp; 1656 struct ps_strings *arginfo; 1657 struct proc *p; 1658 size_t execpath_len; 1659 int error, szsigcode, szps; 1660 char canary[sizeof(long) * 8]; 1661 1662 szps = sizeof(pagesizes[0]) * MAXPAGESIZES; 1663 /* 1664 * Calculate string base and vector table pointers. 1665 * Also deal with signal trampoline code for this exec type. 1666 */ 1667 if (imgp->execpath != NULL && imgp->auxargs != NULL) 1668 execpath_len = strlen(imgp->execpath) + 1; 1669 else 1670 execpath_len = 0; 1671 p = imgp->proc; 1672 szsigcode = 0; 1673 arginfo = (struct ps_strings *)p->p_sysent->sv_psstrings; 1674 imgp->ps_strings = arginfo; 1675 if (p->p_sysent->sv_sigcode_base == 0) { 1676 if (p->p_sysent->sv_szsigcode != NULL) 1677 szsigcode = *(p->p_sysent->sv_szsigcode); 1678 } 1679 destp = (uintptr_t)arginfo; 1680 1681 /* 1682 * install sigcode 1683 */ 1684 if (szsigcode != 0) { 1685 destp -= szsigcode; 1686 destp = rounddown2(destp, sizeof(void *)); 1687 error = copyout(p->p_sysent->sv_sigcode, (void *)destp, 1688 szsigcode); 1689 if (error != 0) 1690 return (error); 1691 } 1692 1693 /* 1694 * Copy the image path for the rtld. 1695 */ 1696 if (execpath_len != 0) { 1697 destp -= execpath_len; 1698 destp = rounddown2(destp, sizeof(void *)); 1699 imgp->execpathp = (void *)destp; 1700 error = copyout(imgp->execpath, imgp->execpathp, execpath_len); 1701 if (error != 0) 1702 return (error); 1703 } 1704 1705 /* 1706 * Prepare the canary for SSP. 1707 */ 1708 arc4rand(canary, sizeof(canary), 0); 1709 destp -= sizeof(canary); 1710 imgp->canary = (void *)destp; 1711 error = copyout(canary, imgp->canary, sizeof(canary)); 1712 if (error != 0) 1713 return (error); 1714 imgp->canarylen = sizeof(canary); 1715 1716 /* 1717 * Prepare the pagesizes array. 1718 */ 1719 destp -= szps; 1720 destp = rounddown2(destp, sizeof(void *)); 1721 imgp->pagesizes = (void *)destp; 1722 error = copyout(pagesizes, imgp->pagesizes, szps); 1723 if (error != 0) 1724 return (error); 1725 imgp->pagesizeslen = szps; 1726 1727 /* 1728 * Allocate room for the argument and environment strings. 1729 */ 1730 destp -= ARG_MAX - imgp->args->stringspace; 1731 destp = rounddown2(destp, sizeof(void *)); 1732 ustringp = destp; 1733 1734 exec_stackgap(imgp, &destp); 1735 1736 if (imgp->auxargs) { 1737 /* 1738 * Allocate room on the stack for the ELF auxargs 1739 * array. It has up to AT_COUNT entries. 1740 */ 1741 destp -= AT_COUNT * sizeof(Elf_Auxinfo); 1742 destp = rounddown2(destp, sizeof(void *)); 1743 } 1744 1745 vectp = (char **)destp; 1746 1747 /* 1748 * Allocate room for the argv[] and env vectors including the 1749 * terminating NULL pointers. 1750 */ 1751 vectp -= imgp->args->argc + 1 + imgp->args->envc + 1; 1752 1753 /* 1754 * vectp also becomes our initial stack base 1755 */ 1756 *stack_base = (uintptr_t)vectp; 1757 1758 stringp = imgp->args->begin_argv; 1759 argc = imgp->args->argc; 1760 envc = imgp->args->envc; 1761 1762 /* 1763 * Copy out strings - arguments and environment. 1764 */ 1765 error = copyout(stringp, (void *)ustringp, 1766 ARG_MAX - imgp->args->stringspace); 1767 if (error != 0) 1768 return (error); 1769 1770 /* 1771 * Fill in "ps_strings" struct for ps, w, etc. 1772 */ 1773 imgp->argv = vectp; 1774 if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 || 1775 suword32(&arginfo->ps_nargvstr, argc) != 0) 1776 return (EFAULT); 1777 1778 /* 1779 * Fill in argument portion of vector table. 1780 */ 1781 for (; argc > 0; --argc) { 1782 if (suword(vectp++, ustringp) != 0) 1783 return (EFAULT); 1784 while (*stringp++ != 0) 1785 ustringp++; 1786 ustringp++; 1787 } 1788 1789 /* a null vector table pointer separates the argp's from the envp's */ 1790 if (suword(vectp++, 0) != 0) 1791 return (EFAULT); 1792 1793 imgp->envv = vectp; 1794 if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 || 1795 suword32(&arginfo->ps_nenvstr, envc) != 0) 1796 return (EFAULT); 1797 1798 /* 1799 * Fill in environment portion of vector table. 1800 */ 1801 for (; envc > 0; --envc) { 1802 if (suword(vectp++, ustringp) != 0) 1803 return (EFAULT); 1804 while (*stringp++ != 0) 1805 ustringp++; 1806 ustringp++; 1807 } 1808 1809 /* end of vector table is a null pointer */ 1810 if (suword(vectp, 0) != 0) 1811 return (EFAULT); 1812 1813 if (imgp->auxargs) { 1814 vectp++; 1815 error = imgp->sysent->sv_copyout_auxargs(imgp, 1816 (uintptr_t)vectp); 1817 if (error != 0) 1818 return (error); 1819 } 1820 1821 return (0); 1822 } 1823 1824 /* 1825 * Check permissions of file to execute. 1826 * Called with imgp->vp locked. 1827 * Return 0 for success or error code on failure. 1828 */ 1829 int 1830 exec_check_permissions(struct image_params *imgp) 1831 { 1832 struct vnode *vp = imgp->vp; 1833 struct vattr *attr = imgp->attr; 1834 struct thread *td; 1835 int error; 1836 1837 td = curthread; 1838 1839 /* Get file attributes */ 1840 error = VOP_GETATTR(vp, attr, td->td_ucred); 1841 if (error) 1842 return (error); 1843 1844 #ifdef MAC 1845 error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp); 1846 if (error) 1847 return (error); 1848 #endif 1849 1850 /* 1851 * 1) Check if file execution is disabled for the filesystem that 1852 * this file resides on. 1853 * 2) Ensure that at least one execute bit is on. Otherwise, a 1854 * privileged user will always succeed, and we don't want this 1855 * to happen unless the file really is executable. 1856 * 3) Ensure that the file is a regular file. 1857 */ 1858 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 1859 (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 || 1860 (attr->va_type != VREG)) 1861 return (EACCES); 1862 1863 /* 1864 * Zero length files can't be exec'd 1865 */ 1866 if (attr->va_size == 0) 1867 return (ENOEXEC); 1868 1869 /* 1870 * Check for execute permission to file based on current credentials. 1871 */ 1872 error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td); 1873 if (error) 1874 return (error); 1875 1876 /* 1877 * Check number of open-for-writes on the file and deny execution 1878 * if there are any. 1879 * 1880 * Add a text reference now so no one can write to the 1881 * executable while we're activating it. 1882 * 1883 * Remember if this was set before and unset it in case this is not 1884 * actually an executable image. 1885 */ 1886 error = VOP_SET_TEXT(vp); 1887 if (error != 0) 1888 return (error); 1889 imgp->textset = true; 1890 1891 /* 1892 * Call filesystem specific open routine (which does nothing in the 1893 * general case). 1894 */ 1895 error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL); 1896 if (error == 0) 1897 imgp->opened = true; 1898 return (error); 1899 } 1900 1901 /* 1902 * Exec handler registration 1903 */ 1904 int 1905 exec_register(const struct execsw *execsw_arg) 1906 { 1907 const struct execsw **es, **xs, **newexecsw; 1908 u_int count = 2; /* New slot and trailing NULL */ 1909 1910 if (execsw) 1911 for (es = execsw; *es; es++) 1912 count++; 1913 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1914 xs = newexecsw; 1915 if (execsw) 1916 for (es = execsw; *es; es++) 1917 *xs++ = *es; 1918 *xs++ = execsw_arg; 1919 *xs = NULL; 1920 if (execsw) 1921 free(execsw, M_TEMP); 1922 execsw = newexecsw; 1923 return (0); 1924 } 1925 1926 int 1927 exec_unregister(const struct execsw *execsw_arg) 1928 { 1929 const struct execsw **es, **xs, **newexecsw; 1930 int count = 1; 1931 1932 if (execsw == NULL) 1933 panic("unregister with no handlers left?\n"); 1934 1935 for (es = execsw; *es; es++) { 1936 if (*es == execsw_arg) 1937 break; 1938 } 1939 if (*es == NULL) 1940 return (ENOENT); 1941 for (es = execsw; *es; es++) 1942 if (*es != execsw_arg) 1943 count++; 1944 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 1945 xs = newexecsw; 1946 for (es = execsw; *es; es++) 1947 if (*es != execsw_arg) 1948 *xs++ = *es; 1949 *xs = NULL; 1950 if (execsw) 1951 free(execsw, M_TEMP); 1952 execsw = newexecsw; 1953 return (0); 1954 }
Cache object: 77ed20ffb124e83f2c5cb0534277a48e
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