exec_elf.c revision 1.45
1 /* $NetBSD: exec_elf.c,v 1.45 2013/04/09 07:39:01 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 1994, 2000, 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 1996 Christopher G. Demetriou 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions 38 * are met: 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 3. The name of the author may not be used to endorse or promote products 45 * derived from this software without specific prior written permission 46 * 47 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 48 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 49 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 50 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 51 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 52 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 53 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 54 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 55 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 56 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 57 */ 58 59 #include <sys/cdefs.h> 60 __KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.45 2013/04/09 07:39:01 skrll Exp $"); 61 62 #ifdef _KERNEL_OPT 63 #include "opt_pax.h" 64 #endif /* _KERNEL_OPT */ 65 66 #include <sys/param.h> 67 #include <sys/proc.h> 68 #include <sys/kmem.h> 69 #include <sys/namei.h> 70 #include <sys/vnode.h> 71 #include <sys/exec.h> 72 #include <sys/exec_elf.h> 73 #include <sys/syscall.h> 74 #include <sys/signalvar.h> 75 #include <sys/mount.h> 76 #include <sys/stat.h> 77 #include <sys/kauth.h> 78 #include <sys/bitops.h> 79 #include <sys/cprng.h> 80 81 #include <sys/cpu.h> 82 #include <machine/reg.h> 83 84 #include <compat/common/compat_util.h> 85 86 #include <sys/pax.h> 87 #include <uvm/uvm_param.h> 88 89 extern struct emul emul_netbsd; 90 91 #define elf_check_header ELFNAME(check_header) 92 #define elf_copyargs ELFNAME(copyargs) 93 #define elf_load_file ELFNAME(load_file) 94 #define elf_load_psection ELFNAME(load_psection) 95 #define exec_elf_makecmds ELFNAME2(exec,makecmds) 96 #define netbsd_elf_signature ELFNAME2(netbsd,signature) 97 #define netbsd_elf_probe ELFNAME2(netbsd,probe) 98 #define coredump ELFNAMEEND(coredump) 99 #define elf_free_emul_arg ELFNAME(free_emul_arg) 100 101 int elf_load_file(struct lwp *, struct exec_package *, char *, 102 struct exec_vmcmd_set *, u_long *, struct elf_args *, Elf_Addr *); 103 void elf_load_psection(struct exec_vmcmd_set *, struct vnode *, 104 const Elf_Phdr *, Elf_Addr *, u_long *, int *, int); 105 106 int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *); 107 int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *, 108 vaddr_t *); 109 110 static void elf_free_emul_arg(void *); 111 112 /* round up and down to page boundaries. */ 113 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 114 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1)) 115 116 /* 117 * Arbitrary limits to avoid DoS for excessive memory allocation. 118 */ 119 #define MAXPHNUM 128 120 #define MAXSHNUM 32768 121 #define MAXNOTESIZE 1024 122 123 static void 124 elf_placedynexec(struct lwp *l, struct exec_package *epp, Elf_Ehdr *eh, 125 Elf_Phdr *ph) 126 { 127 Elf_Addr align, offset; 128 int i; 129 130 for (align = i = 0; i < eh->e_phnum; i++) 131 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align) 132 align = ph[i].p_align; 133 134 #ifdef PAX_ASLR 135 if (pax_aslr_active(l)) { 136 size_t pax_align, l2, delta; 137 uint32_t r; 138 139 pax_align = align; 140 141 r = cprng_fast32(); 142 143 if (pax_align == 0) 144 pax_align = PGSHIFT; 145 l2 = ilog2(pax_align); 146 delta = PAX_ASLR_DELTA(r, l2, PAX_ASLR_DELTA_EXEC_LEN); 147 offset = ELF_TRUNC(delta, pax_align) + PAGE_SIZE; 148 #ifdef PAX_ASLR_DEBUG 149 uprintf("r=0x%x l2=0x%zx PGSHIFT=0x%x Delta=0x%zx\n", r, l2, 150 PGSHIFT, delta); 151 uprintf("pax offset=0x%llx entry=0x%llx\n", 152 (unsigned long long)offset, 153 (unsigned long long)eh->e_entry); 154 #endif /* PAX_ASLR_DEBUG */ 155 } else 156 #endif /* PAX_ASLR */ 157 offset = MAX(align, PAGE_SIZE); 158 159 offset += epp->ep_vm_minaddr; 160 161 for (i = 0; i < eh->e_phnum; i++) 162 ph[i].p_vaddr += offset; 163 eh->e_entry += offset; 164 } 165 166 /* 167 * Copy arguments onto the stack in the normal way, but add some 168 * extra information in case of dynamic binding. 169 */ 170 int 171 elf_copyargs(struct lwp *l, struct exec_package *pack, 172 struct ps_strings *arginfo, char **stackp, void *argp) 173 { 174 size_t len, vlen; 175 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname; 176 struct elf_args *ap; 177 int error; 178 179 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0) 180 return error; 181 182 a = ai; 183 execname = NULL; 184 185 /* 186 * Push extra arguments on the stack needed by dynamically 187 * linked binaries 188 */ 189 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 190 struct vattr *vap = pack->ep_vap; 191 192 a->a_type = AT_PHDR; 193 a->a_v = ap->arg_phaddr; 194 a++; 195 196 a->a_type = AT_PHENT; 197 a->a_v = ap->arg_phentsize; 198 a++; 199 200 a->a_type = AT_PHNUM; 201 a->a_v = ap->arg_phnum; 202 a++; 203 204 a->a_type = AT_PAGESZ; 205 a->a_v = PAGE_SIZE; 206 a++; 207 208 a->a_type = AT_BASE; 209 a->a_v = ap->arg_interp; 210 a++; 211 212 a->a_type = AT_FLAGS; 213 a->a_v = 0; 214 a++; 215 216 a->a_type = AT_ENTRY; 217 a->a_v = ap->arg_entry; 218 a++; 219 220 a->a_type = AT_EUID; 221 if (vap->va_mode & S_ISUID) 222 a->a_v = vap->va_uid; 223 else 224 a->a_v = kauth_cred_geteuid(l->l_cred); 225 a++; 226 227 a->a_type = AT_RUID; 228 a->a_v = kauth_cred_getuid(l->l_cred); 229 a++; 230 231 a->a_type = AT_EGID; 232 if (vap->va_mode & S_ISGID) 233 a->a_v = vap->va_gid; 234 else 235 a->a_v = kauth_cred_getegid(l->l_cred); 236 a++; 237 238 a->a_type = AT_RGID; 239 a->a_v = kauth_cred_getgid(l->l_cred); 240 a++; 241 242 a->a_type = AT_STACKBASE; 243 a->a_v = l->l_proc->p_stackbase; 244 a++; 245 246 if (pack->ep_path) { 247 execname = a; 248 a->a_type = AT_SUN_EXECNAME; 249 a++; 250 } 251 252 exec_free_emul_arg(pack); 253 } 254 255 a->a_type = AT_NULL; 256 a->a_v = 0; 257 a++; 258 259 vlen = (a - ai) * sizeof(ai[0]); 260 261 KASSERT(vlen <= sizeof(ai)); 262 263 if (execname) { 264 char *path = pack->ep_path; 265 execname->a_v = (uintptr_t)(*stackp + vlen); 266 len = strlen(path) + 1; 267 if ((error = copyout(path, (*stackp + vlen), len)) != 0) 268 return error; 269 len = ALIGN(len); 270 } else 271 len = 0; 272 273 if ((error = copyout(ai, *stackp, vlen)) != 0) 274 return error; 275 *stackp += vlen + len; 276 277 return 0; 278 } 279 280 /* 281 * elf_check_header(): 282 * 283 * Check header for validity; return 0 of ok ENOEXEC if error 284 */ 285 int 286 elf_check_header(Elf_Ehdr *eh, int type) 287 { 288 289 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 || 290 eh->e_ident[EI_CLASS] != ELFCLASS) 291 return ENOEXEC; 292 293 switch (eh->e_machine) { 294 295 ELFDEFNNAME(MACHDEP_ID_CASES) 296 297 default: 298 return ENOEXEC; 299 } 300 301 if (ELF_EHDR_FLAGS_OK(eh) == 0) 302 return ENOEXEC; 303 304 if (eh->e_type != type) 305 return ENOEXEC; 306 307 if (eh->e_shnum > MAXSHNUM || eh->e_phnum > MAXPHNUM) 308 return ENOEXEC; 309 310 return 0; 311 } 312 313 /* 314 * elf_load_psection(): 315 * 316 * Load a psection at the appropriate address 317 */ 318 void 319 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp, 320 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int *prot, int flags) 321 { 322 u_long msize, psize, rm, rf; 323 long diff, offset; 324 325 /* 326 * If the user specified an address, then we load there. 327 */ 328 if (*addr == ELFDEFNNAME(NO_ADDR)) 329 *addr = ph->p_vaddr; 330 331 if (ph->p_align > 1) { 332 /* 333 * Make sure we are virtually aligned as we are supposed to be. 334 */ 335 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align); 336 KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align)); 337 /* 338 * But make sure to not map any pages before the start of the 339 * psection by limiting the difference to within a page. 340 */ 341 diff &= PAGE_MASK; 342 } else 343 diff = 0; 344 345 *prot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; 346 *prot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; 347 *prot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; 348 349 /* 350 * Adjust everything so it all starts on a page boundary. 351 */ 352 *addr -= diff; 353 offset = ph->p_offset - diff; 354 *size = ph->p_filesz + diff; 355 msize = ph->p_memsz + diff; 356 357 if (ph->p_align >= PAGE_SIZE) { 358 if ((ph->p_flags & PF_W) != 0) { 359 /* 360 * Because the pagedvn pager can't handle zero fill 361 * of the last data page if it's not page aligned we 362 * map the last page readvn. 363 */ 364 psize = trunc_page(*size); 365 } else { 366 psize = round_page(*size); 367 } 368 } else { 369 psize = *size; 370 } 371 372 if (psize > 0) { 373 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ? 374 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp, 375 offset, *prot, flags); 376 flags &= VMCMD_RELATIVE; 377 } 378 if (psize < *size) { 379 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize, 380 *addr + psize, vp, offset + psize, *prot, flags); 381 } 382 383 /* 384 * Check if we need to extend the size of the segment (does 385 * bss extend page the next page boundary)? 386 */ 387 rm = round_page(*addr + msize); 388 rf = round_page(*addr + *size); 389 390 if (rm != rf) { 391 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 392 0, *prot, flags & VMCMD_RELATIVE); 393 *size = msize; 394 } 395 } 396 397 /* 398 * elf_load_file(): 399 * 400 * Load a file (interpreter/library) pointed to by path 401 * [stolen from coff_load_shlib()]. Made slightly generic 402 * so it might be used externally. 403 */ 404 int 405 elf_load_file(struct lwp *l, struct exec_package *epp, char *path, 406 struct exec_vmcmd_set *vcset, u_long *entryoff, struct elf_args *ap, 407 Elf_Addr *last) 408 { 409 int error, i; 410 struct vnode *vp; 411 struct vattr attr; 412 Elf_Ehdr eh; 413 Elf_Phdr *ph = NULL; 414 const Elf_Phdr *ph0; 415 const Elf_Phdr *base_ph; 416 const Elf_Phdr *last_ph; 417 u_long phsize; 418 Elf_Addr addr = *last; 419 struct proc *p; 420 bool use_topdown; 421 422 p = l->l_proc; 423 424 KASSERT(p->p_vmspace); 425 if (__predict_true(p->p_vmspace != proc0.p_vmspace)) 426 use_topdown = p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN; 427 else 428 #ifdef __USING_TOPDOWN_VM 429 use_topdown = true; 430 #else 431 use_topdown = false; 432 #endif 433 434 /* 435 * 1. open file 436 * 2. read filehdr 437 * 3. map text, data, and bss out of it using VM_* 438 */ 439 vp = epp->ep_interp; 440 if (vp == NULL) { 441 error = emul_find_interp(l, epp, path); 442 if (error != 0) 443 return error; 444 vp = epp->ep_interp; 445 } 446 /* We'll tidy this ourselves - otherwise we have locking issues */ 447 epp->ep_interp = NULL; 448 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 449 450 /* 451 * Similarly, if it's not marked as executable, or it's not a regular 452 * file, we don't allow it to be used. 453 */ 454 if (vp->v_type != VREG) { 455 error = EACCES; 456 goto badunlock; 457 } 458 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0) 459 goto badunlock; 460 461 /* get attributes */ 462 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0) 463 goto badunlock; 464 465 /* 466 * Check mount point. Though we're not trying to exec this binary, 467 * we will be executing code from it, so if the mount point 468 * disallows execution or set-id-ness, we punt or kill the set-id. 469 */ 470 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 471 error = EACCES; 472 goto badunlock; 473 } 474 if (vp->v_mount->mnt_flag & MNT_NOSUID) 475 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 476 477 #ifdef notyet /* XXX cgd 960926 */ 478 XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?) 479 480 XXXps: this problem will make it impossible to use an interpreter 481 from a file system which actually does something in VOP_OPEN 482 #endif 483 484 error = vn_marktext(vp); 485 if (error) 486 goto badunlock; 487 488 VOP_UNLOCK(vp); 489 490 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0) 491 goto bad; 492 493 if ((error = elf_check_header(&eh, ET_DYN)) != 0) 494 goto bad; 495 496 if (eh.e_phnum > MAXPHNUM || eh.e_phnum == 0) { 497 error = ENOEXEC; 498 goto bad; 499 } 500 501 phsize = eh.e_phnum * sizeof(Elf_Phdr); 502 ph = kmem_alloc(phsize, KM_SLEEP); 503 504 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0) 505 goto bad; 506 507 #ifdef ELF_INTERP_NON_RELOCATABLE 508 /* 509 * Evil hack: Only MIPS should be non-relocatable, and the 510 * psections should have a high address (typically 0x5ffe0000). 511 * If it's now relocatable, it should be linked at 0 and the 512 * psections should have zeros in the upper part of the address. 513 * Otherwise, force the load at the linked address. 514 */ 515 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0) 516 *last = ELFDEFNNAME(NO_ADDR); 517 #endif 518 519 /* 520 * If no position to load the interpreter was set by a probe 521 * function, pick the same address that a non-fixed mmap(0, ..) 522 * would (i.e. something safely out of the way). 523 */ 524 if (*last == ELFDEFNNAME(NO_ADDR)) { 525 u_long limit = 0; 526 /* 527 * Find the start and ending addresses of the psections to 528 * be loaded. This will give us the size. 529 */ 530 for (i = 0, ph0 = ph, base_ph = NULL; i < eh.e_phnum; 531 i++, ph0++) { 532 if (ph0->p_type == PT_LOAD) { 533 u_long psize = ph0->p_vaddr + ph0->p_memsz; 534 if (base_ph == NULL) 535 base_ph = ph0; 536 if (psize > limit) 537 limit = psize; 538 } 539 } 540 541 if (base_ph == NULL) { 542 error = ENOEXEC; 543 goto bad; 544 } 545 546 /* 547 * Now compute the size and load address. 548 */ 549 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p, 550 epp->ep_daddr, 551 round_page(limit) - trunc_page(base_ph->p_vaddr)); 552 } else 553 addr = *last; /* may be ELF_LINK_ADDR */ 554 555 /* 556 * Load all the necessary sections 557 */ 558 for (i = 0, ph0 = ph, base_ph = NULL, last_ph = NULL; 559 i < eh.e_phnum; i++, ph0++) { 560 switch (ph0->p_type) { 561 case PT_LOAD: { 562 u_long size; 563 int prot = 0; 564 int flags; 565 566 if (base_ph == NULL) { 567 /* 568 * First encountered psection is always the 569 * base psection. Make sure it's aligned 570 * properly (align down for topdown and align 571 * upwards for not topdown). 572 */ 573 base_ph = ph0; 574 flags = VMCMD_BASE; 575 if (addr == ELF_LINK_ADDR) 576 addr = ph0->p_vaddr; 577 if (use_topdown) 578 addr = ELF_TRUNC(addr, ph0->p_align); 579 else 580 addr = ELF_ROUND(addr, ph0->p_align); 581 } else { 582 u_long limit = round_page(last_ph->p_vaddr 583 + last_ph->p_memsz); 584 u_long base = trunc_page(ph0->p_vaddr); 585 586 /* 587 * If there is a gap in between the psections, 588 * map it as inaccessible so nothing else 589 * mmap'ed will be placed there. 590 */ 591 if (limit != base) { 592 NEW_VMCMD2(vcset, vmcmd_map_zero, 593 base - limit, 594 limit - base_ph->p_vaddr, NULLVP, 595 0, VM_PROT_NONE, VMCMD_RELATIVE); 596 } 597 598 addr = ph0->p_vaddr - base_ph->p_vaddr; 599 flags = VMCMD_RELATIVE; 600 } 601 last_ph = ph0; 602 elf_load_psection(vcset, vp, &ph[i], &addr, 603 &size, &prot, flags); 604 /* 605 * If entry is within this psection then this 606 * must contain the .text section. *entryoff is 607 * relative to the base psection. 608 */ 609 if (eh.e_entry >= ph0->p_vaddr && 610 eh.e_entry < (ph0->p_vaddr + size)) { 611 *entryoff = eh.e_entry - base_ph->p_vaddr; 612 } 613 addr += size; 614 break; 615 } 616 617 case PT_DYNAMIC: 618 case PT_PHDR: 619 break; 620 621 case PT_NOTE: 622 break; 623 624 default: 625 break; 626 } 627 } 628 629 kmem_free(ph, phsize); 630 /* 631 * This value is ignored if TOPDOWN. 632 */ 633 *last = addr; 634 vrele(vp); 635 return 0; 636 637 badunlock: 638 VOP_UNLOCK(vp); 639 640 bad: 641 if (ph != NULL) 642 kmem_free(ph, phsize); 643 #ifdef notyet /* XXX cgd 960926 */ 644 (maybe) VOP_CLOSE it 645 #endif 646 vrele(vp); 647 return error; 648 } 649 650 /* 651 * exec_elf_makecmds(): Prepare an Elf binary's exec package 652 * 653 * First, set of the various offsets/lengths in the exec package. 654 * 655 * Then, mark the text image busy (so it can be demand paged) or error 656 * out if this is not possible. Finally, set up vmcmds for the 657 * text, data, bss, and stack segments. 658 */ 659 int 660 exec_elf_makecmds(struct lwp *l, struct exec_package *epp) 661 { 662 Elf_Ehdr *eh = epp->ep_hdr; 663 Elf_Phdr *ph, *pp; 664 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0; 665 int error, i, nload; 666 char *interp = NULL; 667 u_long phsize; 668 struct elf_args *ap = NULL; 669 bool is_dyn; 670 671 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 672 return ENOEXEC; 673 674 is_dyn = elf_check_header(eh, ET_DYN) == 0; 675 /* 676 * XXX allow for executing shared objects. It seems silly 677 * but other ELF-based systems allow it as well. 678 */ 679 if (elf_check_header(eh, ET_EXEC) != 0 && !is_dyn) 680 return ENOEXEC; 681 682 if (eh->e_phnum > MAXPHNUM || eh->e_phnum == 0) 683 return ENOEXEC; 684 685 error = vn_marktext(epp->ep_vp); 686 if (error) 687 return error; 688 689 /* 690 * Allocate space to hold all the program headers, and read them 691 * from the file 692 */ 693 phsize = eh->e_phnum * sizeof(Elf_Phdr); 694 ph = kmem_alloc(phsize, KM_SLEEP); 695 696 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) != 697 0) 698 goto bad; 699 700 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 701 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 702 703 for (i = 0; i < eh->e_phnum; i++) { 704 pp = &ph[i]; 705 if (pp->p_type == PT_INTERP) { 706 if (pp->p_filesz >= MAXPATHLEN) { 707 error = ENOEXEC; 708 goto bad; 709 } 710 interp = PNBUF_GET(); 711 interp[0] = '\0'; 712 if ((error = exec_read_from(l, epp->ep_vp, 713 pp->p_offset, interp, pp->p_filesz)) != 0) 714 goto bad; 715 break; 716 } 717 } 718 719 /* 720 * On the same architecture, we may be emulating different systems. 721 * See which one will accept this executable. 722 * 723 * Probe functions would normally see if the interpreter (if any) 724 * exists. Emulation packages may possibly replace the interpreter in 725 * interp[] with a changed path (/emul/xxx/<path>). 726 */ 727 pos = ELFDEFNNAME(NO_ADDR); 728 if (epp->ep_esch->u.elf_probe_func) { 729 vaddr_t startp = (vaddr_t)pos; 730 731 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp, 732 &startp); 733 if (error) 734 goto bad; 735 pos = (Elf_Addr)startp; 736 } 737 738 #if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR) 739 l->l_proc->p_pax = epp->ep_pax_flags; 740 #endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */ 741 742 if (is_dyn) 743 elf_placedynexec(l, epp, eh, ph); 744 745 /* 746 * Load all the necessary sections 747 */ 748 for (i = nload = 0; i < eh->e_phnum; i++) { 749 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 750 u_long size = 0; 751 int prot = 0; 752 753 pp = &ph[i]; 754 755 switch (ph[i].p_type) { 756 case PT_LOAD: 757 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 758 &ph[i], &addr, &size, &prot, VMCMD_FIXED); 759 760 /* 761 * Consider this as text segment, if it is executable. 762 * If there is more than one text segment, pick the 763 * largest. 764 */ 765 if (ph[i].p_flags & PF_X) { 766 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) || 767 size > epp->ep_tsize) { 768 epp->ep_taddr = addr; 769 epp->ep_tsize = size; 770 } 771 end_text = addr + size; 772 } else { 773 epp->ep_daddr = addr; 774 epp->ep_dsize = size; 775 } 776 if (ph[i].p_offset == 0) { 777 computed_phdr = ph[i].p_vaddr + eh->e_phoff; 778 } 779 break; 780 781 case PT_SHLIB: 782 /* SCO has these sections. */ 783 case PT_INTERP: 784 /* Already did this one. */ 785 case PT_DYNAMIC: 786 break; 787 case PT_NOTE: 788 break; 789 case PT_PHDR: 790 /* Note address of program headers (in text segment) */ 791 phdr = pp->p_vaddr; 792 break; 793 794 default: 795 /* 796 * Not fatal; we don't need to understand everything. 797 */ 798 break; 799 } 800 } 801 if (interp || (epp->ep_flags & EXEC_FORCEAUX) != 0) { 802 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 803 ap->arg_interp = (vaddr_t)NULL; 804 } 805 806 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 807 epp->ep_daddr = round_page(end_text); 808 epp->ep_dsize = 0; 809 } 810 811 /* 812 * Check if we found a dynamically linked binary and arrange to load 813 * its interpreter 814 */ 815 if (interp) { 816 int j = epp->ep_vmcmds.evs_used; 817 u_long interp_offset; 818 819 if ((error = elf_load_file(l, epp, interp, 820 &epp->ep_vmcmds, &interp_offset, ap, &pos)) != 0) { 821 goto bad; 822 } 823 ap->arg_interp = epp->ep_vmcmds.evs_cmds[j].ev_addr; 824 epp->ep_entry = ap->arg_interp + interp_offset; 825 PNBUF_PUT(interp); 826 } else 827 epp->ep_entry = eh->e_entry; 828 829 if (ap) { 830 ap->arg_phaddr = phdr ? phdr : computed_phdr; 831 ap->arg_phentsize = eh->e_phentsize; 832 ap->arg_phnum = eh->e_phnum; 833 ap->arg_entry = eh->e_entry; 834 epp->ep_emul_arg = ap; 835 epp->ep_emul_arg_free = elf_free_emul_arg; 836 } 837 838 #ifdef ELF_MAP_PAGE_ZERO 839 /* Dell SVR4 maps page zero, yeuch! */ 840 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0, 841 epp->ep_vp, 0, VM_PROT_READ); 842 #endif 843 kmem_free(ph, phsize); 844 return (*epp->ep_esch->es_setup_stack)(l, epp); 845 846 bad: 847 if (interp) 848 PNBUF_PUT(interp); 849 exec_free_emul_arg(epp); 850 kmem_free(ph, phsize); 851 kill_vmcmds(&epp->ep_vmcmds); 852 return error; 853 } 854 855 int 856 netbsd_elf_signature(struct lwp *l, struct exec_package *epp, 857 Elf_Ehdr *eh) 858 { 859 size_t i; 860 Elf_Shdr *sh; 861 Elf_Nhdr *np; 862 size_t shsize; 863 int error; 864 int isnetbsd = 0; 865 char *ndata; 866 867 epp->ep_pax_flags = 0; 868 if (eh->e_shnum > MAXSHNUM || eh->e_shnum == 0) 869 return ENOEXEC; 870 871 shsize = eh->e_shnum * sizeof(Elf_Shdr); 872 sh = kmem_alloc(shsize, KM_SLEEP); 873 error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize); 874 if (error) 875 goto out; 876 877 np = kmem_alloc(MAXNOTESIZE, KM_SLEEP); 878 for (i = 0; i < eh->e_shnum; i++) { 879 Elf_Shdr *shp = &sh[i]; 880 881 if (shp->sh_type != SHT_NOTE || 882 shp->sh_size > MAXNOTESIZE || 883 shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ) 884 continue; 885 886 error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np, 887 shp->sh_size); 888 if (error) 889 continue; 890 891 ndata = (char *)(np + 1); 892 unsigned int maxlen = (unsigned int)(shp->sh_size - 893 ((char *)ndata - (char *)np)); 894 if (maxlen < np->n_namesz) 895 goto bad; 896 switch (np->n_type) { 897 case ELF_NOTE_TYPE_NETBSD_TAG: 898 /* 899 * It is us 900 */ 901 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ && 902 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ && 903 memcmp(ndata, ELF_NOTE_NETBSD_NAME, 904 ELF_NOTE_NETBSD_NAMESZ) == 0) { 905 isnetbsd = 1; 906 break; 907 } 908 /* 909 * Ignore SuSE tags 910 */ 911 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ && 912 memcmp(ndata, ELF_NOTE_SUSE_NAME, 913 ELF_NOTE_SUSE_NAMESZ) == 0) 914 break; 915 /* 916 * Dunno, warn for diagnostic 917 */ 918 goto bad; 919 920 case ELF_NOTE_TYPE_PAX_TAG: 921 if (np->n_namesz != ELF_NOTE_PAX_NAMESZ || 922 np->n_descsz != ELF_NOTE_PAX_DESCSZ || 923 memcmp(ndata, ELF_NOTE_PAX_NAME, 924 ELF_NOTE_PAX_NAMESZ)) { 925 bad: 926 #ifdef DIAGNOSTIC 927 { 928 /* 929 * Ignore GNU tags 930 */ 931 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ && 932 memcmp(ndata, ELF_NOTE_GNU_NAME, 933 ELF_NOTE_GNU_NAMESZ) == 0) 934 break; 935 int ns = MIN(np->n_namesz, maxlen); 936 printf("%s: Unknown elf note type %d: " 937 "[namesz=%d, descsz=%d name=%*.*s]\n", 938 epp->ep_kname, np->n_type, np->n_namesz, 939 np->n_descsz, ns, ns, ndata); 940 } 941 #endif 942 continue; 943 } 944 (void)memcpy(&epp->ep_pax_flags, 945 ndata + ELF_NOTE_PAX_NAMESZ, 946 sizeof(epp->ep_pax_flags)); 947 break; 948 949 case ELF_NOTE_TYPE_SUSE_VERSION_TAG: 950 break; 951 952 default: 953 #ifdef DIAGNOSTIC 954 printf("%s: unknown note type %d\n", epp->ep_kname, 955 np->n_type); 956 #endif 957 break; 958 } 959 } 960 kmem_free(np, MAXNOTESIZE); 961 962 error = isnetbsd ? 0 : ENOEXEC; 963 out: 964 kmem_free(sh, shsize); 965 return error; 966 } 967 968 int 969 netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp, 970 vaddr_t *pos) 971 { 972 int error; 973 974 if ((error = netbsd_elf_signature(l, epp, eh)) != 0) 975 return error; 976 #ifdef ELF_MD_PROBE_FUNC 977 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0) 978 return error; 979 #elif defined(ELF_INTERP_NON_RELOCATABLE) 980 *pos = ELF_LINK_ADDR; 981 #endif 982 epp->ep_flags |= EXEC_FORCEAUX; 983 return 0; 984 } 985 986 void 987 elf_free_emul_arg(void *arg) 988 { 989 struct elf_args *ap = arg; 990 KASSERT(ap != NULL); 991 kmem_free(ap, sizeof(*ap)); 992 } 993
Indexes created Sun Sep 21 20:09:37 GMT 2025