1 /* $NetBSD: exec_elf.c,v 1.81 2015/11/26 13:15:34 martin Exp $ */ 2 3 /*- 4 * Copyright (c) 1994, 2000, 2005, 2015 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 and Maxime Villard. 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 1.81 2015/11/26 13:15:34 martin 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_interp ELFNAME(load_interp) 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 static int 102 elf_load_interp(struct lwp *, struct exec_package *, char *, 103 struct exec_vmcmd_set *, u_long *, Elf_Addr *); 104 static void 105 elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *, 106 Elf_Addr *, u_long *, int); 107 108 int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *); 109 int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *, 110 vaddr_t *); 111 112 static void elf_free_emul_arg(void *); 113 114 /* round up and down to page boundaries. */ 115 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 116 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1)) 117 118 static void 119 elf_placedynexec(struct exec_package *epp, Elf_Ehdr *eh, Elf_Phdr *ph) 120 { 121 Elf_Addr align, offset; 122 int i; 123 124 for (align = i = 0; i < eh->e_phnum; i++) 125 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align) 126 align = ph[i].p_align; 127 128 #ifdef PAX_ASLR 129 if (pax_aslr_epp_active(epp)) { 130 size_t pax_align, l2, delta; 131 uint32_t r; 132 133 pax_align = align; 134 135 r = cprng_fast32(); 136 137 if (pax_align == 0) 138 pax_align = PGSHIFT; 139 l2 = ilog2(pax_align); 140 delta = PAX_ASLR_DELTA(r, l2, PAX_ASLR_DELTA_EXEC_LEN); 141 offset = ELF_TRUNC(delta, pax_align) + PAGE_SIZE; 142 #ifdef PAX_ASLR_DEBUG 143 uprintf("r=0x%x l2=0x%zx PGSHIFT=0x%x Delta=0x%zx\n", r, l2, 144 PGSHIFT, delta); 145 uprintf("pax offset=0x%llx entry=0x%llx\n", 146 (unsigned long long)offset, 147 (unsigned long long)eh->e_entry); 148 #endif /* PAX_ASLR_DEBUG */ 149 } else 150 #endif /* PAX_ASLR */ 151 offset = MAX(align, PAGE_SIZE); 152 153 offset += epp->ep_vm_minaddr; 154 155 for (i = 0; i < eh->e_phnum; i++) 156 ph[i].p_vaddr += offset; 157 epp->ep_entryoffset = offset; 158 eh->e_entry += offset; 159 } 160 161 /* 162 * Copy arguments onto the stack in the normal way, but add some 163 * extra information in case of dynamic binding. 164 */ 165 int 166 elf_copyargs(struct lwp *l, struct exec_package *pack, 167 struct ps_strings *arginfo, char **stackp, void *argp) 168 { 169 size_t len, vlen; 170 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname; 171 struct elf_args *ap; 172 int error; 173 174 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0) 175 return error; 176 177 a = ai; 178 execname = NULL; 179 180 memset(ai, 0, sizeof(ai)); 181 182 /* 183 * Push extra arguments on the stack needed by dynamically 184 * linked binaries 185 */ 186 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 187 struct vattr *vap = pack->ep_vap; 188 189 a->a_type = AT_PHDR; 190 a->a_v = ap->arg_phaddr; 191 a++; 192 193 a->a_type = AT_PHENT; 194 a->a_v = ap->arg_phentsize; 195 a++; 196 197 a->a_type = AT_PHNUM; 198 a->a_v = ap->arg_phnum; 199 a++; 200 201 a->a_type = AT_PAGESZ; 202 a->a_v = PAGE_SIZE; 203 a++; 204 205 a->a_type = AT_BASE; 206 a->a_v = ap->arg_interp; 207 a++; 208 209 a->a_type = AT_FLAGS; 210 a->a_v = 0; 211 a++; 212 213 a->a_type = AT_ENTRY; 214 a->a_v = ap->arg_entry; 215 a++; 216 217 a->a_type = AT_EUID; 218 if (vap->va_mode & S_ISUID) 219 a->a_v = vap->va_uid; 220 else 221 a->a_v = kauth_cred_geteuid(l->l_cred); 222 a++; 223 224 a->a_type = AT_RUID; 225 a->a_v = kauth_cred_getuid(l->l_cred); 226 a++; 227 228 a->a_type = AT_EGID; 229 if (vap->va_mode & S_ISGID) 230 a->a_v = vap->va_gid; 231 else 232 a->a_v = kauth_cred_getegid(l->l_cred); 233 a++; 234 235 a->a_type = AT_RGID; 236 a->a_v = kauth_cred_getgid(l->l_cred); 237 a++; 238 239 a->a_type = AT_STACKBASE; 240 a->a_v = l->l_proc->p_stackbase; 241 a++; 242 243 if (pack->ep_path) { 244 execname = a; 245 a->a_type = AT_SUN_EXECNAME; 246 a++; 247 } 248 249 exec_free_emul_arg(pack); 250 } 251 252 a->a_type = AT_NULL; 253 a->a_v = 0; 254 a++; 255 256 vlen = (a - ai) * sizeof(ai[0]); 257 258 KASSERT(vlen <= sizeof(ai)); 259 260 if (execname) { 261 char *path = pack->ep_path; 262 execname->a_v = (uintptr_t)(*stackp + vlen); 263 len = strlen(path) + 1; 264 if ((error = copyout(path, (*stackp + vlen), len)) != 0) 265 return error; 266 len = ALIGN(len); 267 } else 268 len = 0; 269 270 if ((error = copyout(ai, *stackp, vlen)) != 0) 271 return error; 272 *stackp += vlen + len; 273 274 return 0; 275 } 276 277 /* 278 * elf_check_header(): 279 * 280 * Check header for validity; return 0 if ok, ENOEXEC if error 281 */ 282 int 283 elf_check_header(Elf_Ehdr *eh) 284 { 285 286 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 || 287 eh->e_ident[EI_CLASS] != ELFCLASS) 288 return ENOEXEC; 289 290 switch (eh->e_machine) { 291 292 ELFDEFNNAME(MACHDEP_ID_CASES) 293 294 default: 295 return ENOEXEC; 296 } 297 298 if (ELF_EHDR_FLAGS_OK(eh) == 0) 299 return ENOEXEC; 300 301 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM) 302 return ENOEXEC; 303 304 return 0; 305 } 306 307 /* 308 * elf_load_psection(): 309 * 310 * Load a psection at the appropriate address 311 */ 312 static void 313 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp, 314 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags) 315 { 316 u_long msize, psize, rm, rf; 317 long diff, offset; 318 int vmprot = 0; 319 320 /* 321 * If the user specified an address, then we load there. 322 */ 323 if (*addr == ELFDEFNNAME(NO_ADDR)) 324 *addr = ph->p_vaddr; 325 326 if (ph->p_align > 1) { 327 /* 328 * Make sure we are virtually aligned as we are supposed to be. 329 */ 330 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align); 331 KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align)); 332 /* 333 * But make sure to not map any pages before the start of the 334 * psection by limiting the difference to within a page. 335 */ 336 diff &= PAGE_MASK; 337 } else 338 diff = 0; 339 340 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; 341 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; 342 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; 343 344 /* 345 * Adjust everything so it all starts on a page boundary. 346 */ 347 *addr -= diff; 348 offset = ph->p_offset - diff; 349 *size = ph->p_filesz + diff; 350 msize = ph->p_memsz + diff; 351 352 if (ph->p_align >= PAGE_SIZE) { 353 if ((ph->p_flags & PF_W) != 0) { 354 /* 355 * Because the pagedvn pager can't handle zero fill 356 * of the last data page if it's not page aligned we 357 * map the last page readvn. 358 */ 359 psize = trunc_page(*size); 360 } else { 361 psize = round_page(*size); 362 } 363 } else { 364 psize = *size; 365 } 366 367 if (psize > 0) { 368 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ? 369 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp, 370 offset, vmprot, flags); 371 flags &= VMCMD_RELATIVE; 372 } 373 if (psize < *size) { 374 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize, 375 *addr + psize, vp, offset + psize, vmprot, flags); 376 } 377 378 /* 379 * Check if we need to extend the size of the segment (does 380 * bss extend page the next page boundary)? 381 */ 382 rm = round_page(*addr + msize); 383 rf = round_page(*addr + *size); 384 385 if (rm != rf) { 386 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 387 0, vmprot, flags & VMCMD_RELATIVE); 388 *size = msize; 389 } 390 } 391 392 /* 393 * elf_load_interp(): 394 * 395 * Load an interpreter pointed to by path. 396 */ 397 static int 398 elf_load_interp(struct lwp *l, struct exec_package *epp, char *path, 399 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last) 400 { 401 int error, i; 402 struct vnode *vp; 403 struct vattr attr; 404 Elf_Ehdr eh; 405 Elf_Phdr *ph = NULL; 406 const Elf_Phdr *base_ph; 407 const Elf_Phdr *last_ph; 408 u_long phsize; 409 Elf_Addr addr = *last; 410 struct proc *p; 411 bool use_topdown; 412 413 p = l->l_proc; 414 415 KASSERT(p->p_vmspace); 416 KASSERT(p->p_vmspace != proc0.p_vmspace); 417 418 #ifdef __USE_TOPDOWN_VM 419 use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM; 420 #else 421 use_topdown = false; 422 #endif 423 424 /* 425 * 1. open file 426 * 2. read filehdr 427 * 3. map text, data, and bss out of it using VM_* 428 */ 429 vp = epp->ep_interp; 430 if (vp == NULL) { 431 error = emul_find_interp(l, epp, path); 432 if (error != 0) 433 return error; 434 vp = epp->ep_interp; 435 } 436 /* We'll tidy this ourselves - otherwise we have locking issues */ 437 epp->ep_interp = NULL; 438 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 439 440 /* 441 * Similarly, if it's not marked as executable, or it's not a regular 442 * file, we don't allow it to be used. 443 */ 444 if (vp->v_type != VREG) { 445 error = EACCES; 446 goto badunlock; 447 } 448 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0) 449 goto badunlock; 450 451 /* get attributes */ 452 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0) 453 goto badunlock; 454 455 /* 456 * Check mount point. Though we're not trying to exec this binary, 457 * we will be executing code from it, so if the mount point 458 * disallows execution or set-id-ness, we punt or kill the set-id. 459 */ 460 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 461 error = EACCES; 462 goto badunlock; 463 } 464 if (vp->v_mount->mnt_flag & MNT_NOSUID) 465 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 466 467 error = vn_marktext(vp); 468 if (error) 469 goto badunlock; 470 471 VOP_UNLOCK(vp); 472 473 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0) 474 goto bad; 475 476 if ((error = elf_check_header(&eh)) != 0) 477 goto bad; 478 if (eh.e_type != ET_DYN || eh.e_phnum == 0) { 479 error = ENOEXEC; 480 goto bad; 481 } 482 483 phsize = eh.e_phnum * sizeof(Elf_Phdr); 484 ph = kmem_alloc(phsize, KM_SLEEP); 485 486 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0) 487 goto bad; 488 489 #ifdef ELF_INTERP_NON_RELOCATABLE 490 /* 491 * Evil hack: Only MIPS should be non-relocatable, and the 492 * psections should have a high address (typically 0x5ffe0000). 493 * If it's now relocatable, it should be linked at 0 and the 494 * psections should have zeros in the upper part of the address. 495 * Otherwise, force the load at the linked address. 496 */ 497 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0) 498 *last = ELFDEFNNAME(NO_ADDR); 499 #endif 500 501 /* 502 * If no position to load the interpreter was set by a probe 503 * function, pick the same address that a non-fixed mmap(0, ..) 504 * would (i.e. something safely out of the way). 505 */ 506 if (*last == ELFDEFNNAME(NO_ADDR)) { 507 u_long limit = 0; 508 /* 509 * Find the start and ending addresses of the psections to 510 * be loaded. This will give us the size. 511 */ 512 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) { 513 if (ph[i].p_type == PT_LOAD) { 514 u_long psize = ph[i].p_vaddr + ph[i].p_memsz; 515 if (base_ph == NULL) 516 base_ph = &ph[i]; 517 if (psize > limit) 518 limit = psize; 519 } 520 } 521 522 if (base_ph == NULL) { 523 error = ENOEXEC; 524 goto bad; 525 } 526 527 /* 528 * Now compute the size and load address. 529 */ 530 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p, 531 epp->ep_daddr, 532 round_page(limit) - trunc_page(base_ph->p_vaddr), 533 use_topdown); 534 } else { 535 addr = *last; /* may be ELF_LINK_ADDR */ 536 } 537 538 /* 539 * Load all the necessary sections 540 */ 541 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) { 542 switch (ph[i].p_type) { 543 case PT_LOAD: { 544 u_long size; 545 int flags; 546 547 if (base_ph == NULL) { 548 /* 549 * First encountered psection is always the 550 * base psection. Make sure it's aligned 551 * properly (align down for topdown and align 552 * upwards for not topdown). 553 */ 554 base_ph = &ph[i]; 555 flags = VMCMD_BASE; 556 if (addr == ELF_LINK_ADDR) 557 addr = ph[i].p_vaddr; 558 if (use_topdown) 559 addr = ELF_TRUNC(addr, ph[i].p_align); 560 else 561 addr = ELF_ROUND(addr, ph[i].p_align); 562 } else { 563 u_long limit = round_page(last_ph->p_vaddr 564 + last_ph->p_memsz); 565 u_long base = trunc_page(ph[i].p_vaddr); 566 567 /* 568 * If there is a gap in between the psections, 569 * map it as inaccessible so nothing else 570 * mmap'ed will be placed there. 571 */ 572 if (limit != base) { 573 NEW_VMCMD2(vcset, vmcmd_map_zero, 574 base - limit, 575 limit - base_ph->p_vaddr, NULLVP, 576 0, VM_PROT_NONE, VMCMD_RELATIVE); 577 } 578 579 addr = ph[i].p_vaddr - base_ph->p_vaddr; 580 flags = VMCMD_RELATIVE; 581 } 582 last_ph = &ph[i]; 583 elf_load_psection(vcset, vp, &ph[i], &addr, 584 &size, flags); 585 /* 586 * If entry is within this psection then this 587 * must contain the .text section. *entryoff is 588 * relative to the base psection. 589 */ 590 if (eh.e_entry >= ph[i].p_vaddr && 591 eh.e_entry < (ph[i].p_vaddr + size)) { 592 *entryoff = eh.e_entry - base_ph->p_vaddr; 593 } 594 addr += size; 595 break; 596 } 597 598 default: 599 break; 600 } 601 } 602 603 kmem_free(ph, phsize); 604 /* 605 * This value is ignored if TOPDOWN. 606 */ 607 *last = addr; 608 vrele(vp); 609 return 0; 610 611 badunlock: 612 VOP_UNLOCK(vp); 613 614 bad: 615 if (ph != NULL) 616 kmem_free(ph, phsize); 617 vrele(vp); 618 return error; 619 } 620 621 /* 622 * exec_elf_makecmds(): Prepare an Elf binary's exec package 623 * 624 * First, set of the various offsets/lengths in the exec package. 625 * 626 * Then, mark the text image busy (so it can be demand paged) or error 627 * out if this is not possible. Finally, set up vmcmds for the 628 * text, data, bss, and stack segments. 629 */ 630 int 631 exec_elf_makecmds(struct lwp *l, struct exec_package *epp) 632 { 633 Elf_Ehdr *eh = epp->ep_hdr; 634 Elf_Phdr *ph, *pp; 635 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0; 636 int error, i; 637 char *interp = NULL; 638 u_long phsize; 639 struct elf_args *ap; 640 bool is_dyn = false; 641 642 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 643 return ENOEXEC; 644 if ((error = elf_check_header(eh)) != 0) 645 return error; 646 647 if (eh->e_type == ET_DYN) 648 /* PIE, and some libs have an entry point */ 649 is_dyn = true; 650 else if (eh->e_type != ET_EXEC) 651 return ENOEXEC; 652 653 if (eh->e_phnum == 0) 654 return ENOEXEC; 655 656 error = vn_marktext(epp->ep_vp); 657 if (error) 658 return error; 659 660 /* 661 * Allocate space to hold all the program headers, and read them 662 * from the file 663 */ 664 phsize = eh->e_phnum * sizeof(Elf_Phdr); 665 ph = kmem_alloc(phsize, KM_SLEEP); 666 667 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) != 668 0) 669 goto bad; 670 671 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 672 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 673 674 for (i = 0; i < eh->e_phnum; i++) { 675 pp = &ph[i]; 676 if (pp->p_type == PT_INTERP) { 677 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) { 678 error = ENOEXEC; 679 goto bad; 680 } 681 interp = PNBUF_GET(); 682 if ((error = exec_read_from(l, epp->ep_vp, 683 pp->p_offset, interp, pp->p_filesz)) != 0) 684 goto bad; 685 /* Ensure interp is NUL-terminated and of the expected length */ 686 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) { 687 error = ENOEXEC; 688 goto bad; 689 } 690 break; 691 } 692 } 693 694 /* 695 * On the same architecture, we may be emulating different systems. 696 * See which one will accept this executable. 697 * 698 * Probe functions would normally see if the interpreter (if any) 699 * exists. Emulation packages may possibly replace the interpreter in 700 * interp with a changed path (/emul/xxx/<path>). 701 */ 702 pos = ELFDEFNNAME(NO_ADDR); 703 if (epp->ep_esch->u.elf_probe_func) { 704 vaddr_t startp = (vaddr_t)pos; 705 706 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp, 707 &startp); 708 if (error) 709 goto bad; 710 pos = (Elf_Addr)startp; 711 } 712 713 if (is_dyn) 714 elf_placedynexec(epp, eh, ph); 715 716 /* 717 * Load all the necessary sections 718 */ 719 for (i = 0; i < eh->e_phnum; i++) { 720 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 721 u_long size = 0; 722 723 switch (ph[i].p_type) { 724 case PT_LOAD: 725 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 726 &ph[i], &addr, &size, VMCMD_FIXED); 727 728 /* 729 * Consider this as text segment, if it is executable. 730 * If there is more than one text segment, pick the 731 * largest. 732 */ 733 if (ph[i].p_flags & PF_X) { 734 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) || 735 size > epp->ep_tsize) { 736 epp->ep_taddr = addr; 737 epp->ep_tsize = size; 738 } 739 end_text = addr + size; 740 } else { 741 epp->ep_daddr = addr; 742 epp->ep_dsize = size; 743 } 744 if (ph[i].p_offset == 0) { 745 computed_phdr = ph[i].p_vaddr + eh->e_phoff; 746 } 747 break; 748 749 case PT_SHLIB: 750 /* SCO has these sections. */ 751 case PT_INTERP: 752 /* Already did this one. */ 753 case PT_DYNAMIC: 754 case PT_NOTE: 755 break; 756 case PT_PHDR: 757 /* Note address of program headers (in text segment) */ 758 phdr = ph[i].p_vaddr; 759 break; 760 761 default: 762 /* 763 * Not fatal; we don't need to understand everything. 764 */ 765 break; 766 } 767 } 768 769 if (epp->ep_vmcmds.evs_used == 0) { 770 /* No VMCMD; there was no PT_LOAD section, or those 771 * sections were empty */ 772 error = ENOEXEC; 773 goto bad; 774 } 775 776 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 777 epp->ep_daddr = round_page(end_text); 778 epp->ep_dsize = 0; 779 } 780 781 /* 782 * Check if we found a dynamically linked binary and arrange to load 783 * its interpreter 784 */ 785 if (interp) { 786 u_int nused = epp->ep_vmcmds.evs_used; 787 u_long interp_offset = 0; 788 789 if ((error = elf_load_interp(l, epp, interp, 790 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) { 791 goto bad; 792 } 793 if (epp->ep_vmcmds.evs_used == nused) { 794 /* elf_load_interp() has not set up any new VMCMD */ 795 error = ENOEXEC; 796 goto bad; 797 } 798 799 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 800 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr; 801 epp->ep_entryoffset = interp_offset; 802 epp->ep_entry = ap->arg_interp + interp_offset; 803 PNBUF_PUT(interp); 804 interp = NULL; 805 } else { 806 epp->ep_entry = eh->e_entry; 807 if (epp->ep_flags & EXEC_FORCEAUX) { 808 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 809 ap->arg_interp = (vaddr_t)NULL; 810 } else 811 ap = NULL; 812 } 813 814 if (ap) { 815 ap->arg_phaddr = phdr ? phdr : computed_phdr; 816 ap->arg_phentsize = eh->e_phentsize; 817 ap->arg_phnum = eh->e_phnum; 818 ap->arg_entry = eh->e_entry; 819 epp->ep_emul_arg = ap; 820 epp->ep_emul_arg_free = elf_free_emul_arg; 821 } 822 823 #ifdef ELF_MAP_PAGE_ZERO 824 /* Dell SVR4 maps page zero, yeuch! */ 825 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0, 826 epp->ep_vp, 0, VM_PROT_READ); 827 #endif 828 829 error = (*epp->ep_esch->es_setup_stack)(l, epp); 830 if (error) 831 goto bad; 832 833 kmem_free(ph, phsize); 834 return 0; 835 836 bad: 837 if (interp) 838 PNBUF_PUT(interp); 839 exec_free_emul_arg(epp); 840 kmem_free(ph, phsize); 841 kill_vmcmds(&epp->ep_vmcmds); 842 return error; 843 } 844 845 int 846 netbsd_elf_signature(struct lwp *l, struct exec_package *epp, 847 Elf_Ehdr *eh) 848 { 849 size_t i; 850 Elf_Shdr *sh; 851 Elf_Nhdr *np; 852 size_t shsize, nsize; 853 int error; 854 int isnetbsd = 0; 855 char *ndata, *ndesc; 856 857 #ifdef DIAGNOSTIC 858 const char *badnote; 859 #define BADNOTE(n) badnote = (n) 860 #else 861 #define BADNOTE(n) 862 #endif 863 864 epp->ep_pax_flags = 0; 865 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_shnum == 0) 866 return ENOEXEC; 867 868 shsize = eh->e_shnum * sizeof(Elf_Shdr); 869 sh = kmem_alloc(shsize, KM_SLEEP); 870 error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize); 871 if (error) 872 goto out; 873 874 np = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP); 875 for (i = 0; i < eh->e_shnum; i++) { 876 Elf_Shdr *shp = &sh[i]; 877 878 if (shp->sh_type != SHT_NOTE || 879 shp->sh_size > ELF_MAXNOTESIZE || 880 shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ) 881 continue; 882 883 error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np, 884 shp->sh_size); 885 if (error) 886 continue; 887 888 /* Point to the note, skip the header */ 889 ndata = (char *)(np + 1); 890 891 /* 892 * Padding is present if necessary to ensure 4-byte alignment. 893 * The actual section size is therefore: 894 * header size + 4-byte aligned name + 4-byte aligned desc 895 * Ensure this size is consistent with what is indicated 896 * in sh_size. The first check avoids integer overflows. 897 * 898 * Binaries from before NetBSD 1.6 have two notes in the same 899 * note section. The second note was never used, so as long as 900 * the section is at least as big as it should be, it's ok. 901 * These binaries also have a second note section with a note of 902 * type ELF_NOTE_TYPE_NETBSD_TAG, which can be ignored as well. 903 */ 904 if (np->n_namesz > shp->sh_size || np->n_descsz > shp->sh_size) { 905 BADNOTE("note size limit"); 906 goto bad; 907 } 908 nsize = sizeof(*np) + roundup(np->n_namesz, 4) + 909 roundup(np->n_descsz, 4); 910 if (nsize > shp->sh_size) { 911 BADNOTE("note size"); 912 goto bad; 913 } 914 ndesc = ndata + roundup(np->n_namesz, 4); 915 916 switch (np->n_type) { 917 case ELF_NOTE_TYPE_NETBSD_TAG: 918 /* It is us */ 919 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ && 920 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ && 921 memcmp(ndata, ELF_NOTE_NETBSD_NAME, 922 ELF_NOTE_NETBSD_NAMESZ) == 0) { 923 memcpy(&epp->ep_osversion, ndesc, 924 ELF_NOTE_NETBSD_DESCSZ); 925 isnetbsd = 1; 926 break; 927 } 928 929 /* 930 * Ignore SuSE tags; SuSE's n_type is the same the 931 * NetBSD one. 932 */ 933 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ && 934 memcmp(ndata, ELF_NOTE_SUSE_NAME, 935 ELF_NOTE_SUSE_NAMESZ) == 0) 936 break; 937 /* 938 * Ignore old GCC 939 */ 940 if (np->n_namesz == ELF_NOTE_OGCC_NAMESZ && 941 memcmp(ndata, ELF_NOTE_OGCC_NAME, 942 ELF_NOTE_OGCC_NAMESZ) == 0) 943 break; 944 BADNOTE("NetBSD tag"); 945 goto bad; 946 947 case ELF_NOTE_TYPE_PAX_TAG: 948 if (np->n_namesz == ELF_NOTE_PAX_NAMESZ && 949 np->n_descsz == ELF_NOTE_PAX_DESCSZ && 950 memcmp(ndata, ELF_NOTE_PAX_NAME, 951 ELF_NOTE_PAX_NAMESZ) == 0) { 952 uint32_t flags; 953 memcpy(&flags, ndesc, sizeof(flags)); 954 #if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR) 955 /* Convert the flags and insert them into 956 * the exec package. */ 957 pax_setup_elf_flags(epp, flags); 958 #else 959 (void)flags; /* UNUSED */ 960 #endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */ 961 break; 962 } 963 BADNOTE("PaX tag"); 964 goto bad; 965 966 case ELF_NOTE_TYPE_MARCH_TAG: 967 /* Copy the machine arch into the package. */ 968 if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ 969 && memcmp(ndata, ELF_NOTE_MARCH_NAME, 970 ELF_NOTE_MARCH_NAMESZ) == 0) { 971 /* Do not truncate the buffer */ 972 if (np->n_descsz > sizeof(epp->ep_machine_arch)) { 973 BADNOTE("description size limit"); 974 goto bad; 975 } 976 /* 977 * Ensure ndesc is NUL-terminated and of the 978 * expected length. 979 */ 980 if (strnlen(ndesc, np->n_descsz) + 1 != 981 np->n_descsz) { 982 BADNOTE("description size"); 983 goto bad; 984 } 985 strlcpy(epp->ep_machine_arch, ndesc, 986 sizeof(epp->ep_machine_arch)); 987 break; 988 } 989 BADNOTE("march tag"); 990 goto bad; 991 992 case ELF_NOTE_TYPE_MCMODEL_TAG: 993 /* arch specific check for code model */ 994 #ifdef ELF_MD_MCMODEL_CHECK 995 if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ 996 && memcmp(ndata, ELF_NOTE_MCMODEL_NAME, 997 ELF_NOTE_MCMODEL_NAMESZ) == 0) { 998 ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz); 999 break; 1000 } 1001 BADNOTE("mcmodel tag"); 1002 goto bad; 1003 #endif 1004 break; 1005 1006 case ELF_NOTE_TYPE_SUSE_VERSION_TAG: 1007 break; 1008 1009 case ELF_NOTE_TYPE_GO_BUILDID_TAG: 1010 break; 1011 1012 default: 1013 BADNOTE("unknown tag"); 1014 bad: 1015 #ifdef DIAGNOSTIC 1016 /* Ignore GNU tags */ 1017 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ && 1018 memcmp(ndata, ELF_NOTE_GNU_NAME, 1019 ELF_NOTE_GNU_NAMESZ) == 0) 1020 break; 1021 1022 int ns = MIN(np->n_namesz, shp->sh_size - sizeof(*np)); 1023 printf("%s: Unknown elf note type %d (%s): " 1024 "[namesz=%d, descsz=%d name=%-*.*s]\n", 1025 epp->ep_kname, np->n_type, badnote, np->n_namesz, 1026 np->n_descsz, ns, ns, ndata); 1027 #endif 1028 break; 1029 } 1030 } 1031 kmem_free(np, ELF_MAXNOTESIZE); 1032 1033 error = isnetbsd ? 0 : ENOEXEC; 1034 out: 1035 kmem_free(sh, shsize); 1036 return error; 1037 } 1038 1039 int 1040 netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp, 1041 vaddr_t *pos) 1042 { 1043 int error; 1044 1045 if ((error = netbsd_elf_signature(l, epp, eh)) != 0) 1046 return error; 1047 #ifdef ELF_MD_PROBE_FUNC 1048 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0) 1049 return error; 1050 #elif defined(ELF_INTERP_NON_RELOCATABLE) 1051 *pos = ELF_LINK_ADDR; 1052 #endif 1053 epp->ep_flags |= EXEC_FORCEAUX; 1054 return 0; 1055 } 1056 1057 void 1058 elf_free_emul_arg(void *arg) 1059 { 1060 struct elf_args *ap = arg; 1061 KASSERT(ap != NULL); 1062 kmem_free(ap, sizeof(*ap)); 1063 } 1064