1 /* $NetBSD: exec_elf.c,v 1.66 2014/05/15 19:37:22 christos 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 1.66 2014/05/15 19:37:22 christos 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 /* 119 * Arbitrary limits to avoid DoS for excessive memory allocation. 120 */ 121 #define MAXPHNUM 128 122 #define MAXSHNUM 32768 123 #define MAXNOTESIZE 1024 124 125 static void 126 elf_placedynexec(struct lwp *l, struct exec_package *epp, Elf_Ehdr *eh, 127 Elf_Phdr *ph) 128 { 129 Elf_Addr align, offset; 130 int i; 131 132 for (align = i = 0; i < eh->e_phnum; i++) 133 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align) 134 align = ph[i].p_align; 135 136 #ifdef PAX_ASLR 137 if (pax_aslr_active(l)) { 138 size_t pax_align, l2, delta; 139 uint32_t r; 140 141 pax_align = align; 142 143 r = cprng_fast32(); 144 145 if (pax_align == 0) 146 pax_align = PGSHIFT; 147 l2 = ilog2(pax_align); 148 delta = PAX_ASLR_DELTA(r, l2, PAX_ASLR_DELTA_EXEC_LEN); 149 offset = ELF_TRUNC(delta, pax_align) + PAGE_SIZE; 150 #ifdef PAX_ASLR_DEBUG 151 uprintf("r=0x%x l2=0x%zx PGSHIFT=0x%x Delta=0x%zx\n", r, l2, 152 PGSHIFT, delta); 153 uprintf("pax offset=0x%llx entry=0x%llx\n", 154 (unsigned long long)offset, 155 (unsigned long long)eh->e_entry); 156 #endif /* PAX_ASLR_DEBUG */ 157 } else 158 #endif /* PAX_ASLR */ 159 offset = MAX(align, PAGE_SIZE); 160 161 offset += epp->ep_vm_minaddr; 162 163 for (i = 0; i < eh->e_phnum; i++) 164 ph[i].p_vaddr += offset; 165 epp->ep_entryoffset = offset; 166 eh->e_entry += offset; 167 } 168 169 /* 170 * Copy arguments onto the stack in the normal way, but add some 171 * extra information in case of dynamic binding. 172 */ 173 int 174 elf_copyargs(struct lwp *l, struct exec_package *pack, 175 struct ps_strings *arginfo, char **stackp, void *argp) 176 { 177 size_t len, vlen; 178 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname; 179 struct elf_args *ap; 180 int error; 181 182 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0) 183 return error; 184 185 a = ai; 186 execname = NULL; 187 188 /* 189 * Push extra arguments on the stack needed by dynamically 190 * linked binaries 191 */ 192 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 193 struct vattr *vap = pack->ep_vap; 194 195 a->a_type = AT_PHDR; 196 a->a_v = ap->arg_phaddr; 197 a++; 198 199 a->a_type = AT_PHENT; 200 a->a_v = ap->arg_phentsize; 201 a++; 202 203 a->a_type = AT_PHNUM; 204 a->a_v = ap->arg_phnum; 205 a++; 206 207 a->a_type = AT_PAGESZ; 208 a->a_v = PAGE_SIZE; 209 a++; 210 211 a->a_type = AT_BASE; 212 a->a_v = ap->arg_interp; 213 a++; 214 215 a->a_type = AT_FLAGS; 216 a->a_v = 0; 217 a++; 218 219 a->a_type = AT_ENTRY; 220 a->a_v = ap->arg_entry; 221 a++; 222 223 a->a_type = AT_EUID; 224 if (vap->va_mode & S_ISUID) 225 a->a_v = vap->va_uid; 226 else 227 a->a_v = kauth_cred_geteuid(l->l_cred); 228 a++; 229 230 a->a_type = AT_RUID; 231 a->a_v = kauth_cred_getuid(l->l_cred); 232 a++; 233 234 a->a_type = AT_EGID; 235 if (vap->va_mode & S_ISGID) 236 a->a_v = vap->va_gid; 237 else 238 a->a_v = kauth_cred_getegid(l->l_cred); 239 a++; 240 241 a->a_type = AT_RGID; 242 a->a_v = kauth_cred_getgid(l->l_cred); 243 a++; 244 245 a->a_type = AT_STACKBASE; 246 a->a_v = l->l_proc->p_stackbase; 247 a++; 248 249 if (pack->ep_path) { 250 execname = a; 251 a->a_type = AT_SUN_EXECNAME; 252 a++; 253 } 254 255 exec_free_emul_arg(pack); 256 } 257 258 a->a_type = AT_NULL; 259 a->a_v = 0; 260 a++; 261 262 vlen = (a - ai) * sizeof(ai[0]); 263 264 KASSERT(vlen <= sizeof(ai)); 265 266 if (execname) { 267 char *path = pack->ep_path; 268 execname->a_v = (uintptr_t)(*stackp + vlen); 269 len = strlen(path) + 1; 270 if ((error = copyout(path, (*stackp + vlen), len)) != 0) 271 return error; 272 len = ALIGN(len); 273 } else 274 len = 0; 275 276 if ((error = copyout(ai, *stackp, vlen)) != 0) 277 return error; 278 *stackp += vlen + len; 279 280 return 0; 281 } 282 283 /* 284 * elf_check_header(): 285 * 286 * Check header for validity; return 0 if ok, ENOEXEC if error 287 */ 288 int 289 elf_check_header(Elf_Ehdr *eh) 290 { 291 292 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 || 293 eh->e_ident[EI_CLASS] != ELFCLASS) 294 return ENOEXEC; 295 296 switch (eh->e_machine) { 297 298 ELFDEFNNAME(MACHDEP_ID_CASES) 299 300 default: 301 return ENOEXEC; 302 } 303 304 if (ELF_EHDR_FLAGS_OK(eh) == 0) 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 static 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 flags) 321 { 322 u_long msize, psize, rm, rf; 323 long diff, offset; 324 int vmprot = 0; 325 326 /* 327 * If the user specified an address, then we load there. 328 */ 329 if (*addr == ELFDEFNNAME(NO_ADDR)) 330 *addr = ph->p_vaddr; 331 332 if (ph->p_align > 1) { 333 /* 334 * Make sure we are virtually aligned as we are supposed to be. 335 */ 336 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align); 337 KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align)); 338 /* 339 * But make sure to not map any pages before the start of the 340 * psection by limiting the difference to within a page. 341 */ 342 diff &= PAGE_MASK; 343 } else 344 diff = 0; 345 346 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; 347 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; 348 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; 349 350 /* 351 * Adjust everything so it all starts on a page boundary. 352 */ 353 *addr -= diff; 354 offset = ph->p_offset - diff; 355 *size = ph->p_filesz + diff; 356 msize = ph->p_memsz + diff; 357 358 if (ph->p_align >= PAGE_SIZE) { 359 if ((ph->p_flags & PF_W) != 0) { 360 /* 361 * Because the pagedvn pager can't handle zero fill 362 * of the last data page if it's not page aligned we 363 * map the last page readvn. 364 */ 365 psize = trunc_page(*size); 366 } else { 367 psize = round_page(*size); 368 } 369 } else { 370 psize = *size; 371 } 372 373 if (psize > 0) { 374 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ? 375 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp, 376 offset, vmprot, flags); 377 flags &= VMCMD_RELATIVE; 378 } 379 if (psize < *size) { 380 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize, 381 *addr + psize, vp, offset + psize, vmprot, flags); 382 } 383 384 /* 385 * Check if we need to extend the size of the segment (does 386 * bss extend page the next page boundary)? 387 */ 388 rm = round_page(*addr + msize); 389 rf = round_page(*addr + *size); 390 391 if (rm != rf) { 392 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 393 0, vmprot, flags & VMCMD_RELATIVE); 394 *size = msize; 395 } 396 } 397 398 /* 399 * elf_load_interp(): 400 * 401 * Load an interpreter pointed to by path. 402 */ 403 static int 404 elf_load_interp(struct lwp *l, struct exec_package *epp, char *path, 405 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last) 406 { 407 int error, i; 408 struct vnode *vp; 409 struct vattr attr; 410 Elf_Ehdr eh; 411 Elf_Phdr *ph = NULL; 412 const Elf_Phdr *base_ph; 413 const Elf_Phdr *last_ph; 414 u_long phsize; 415 Elf_Addr addr = *last; 416 struct proc *p; 417 bool use_topdown; 418 419 p = l->l_proc; 420 421 KASSERT(p->p_vmspace); 422 if (__predict_true(p->p_vmspace != proc0.p_vmspace)) { 423 use_topdown = p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN; 424 } else { 425 #ifdef __USE_TOPDOWN_VM 426 use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM; 427 #else 428 use_topdown = false; 429 #endif 430 } 431 432 /* 433 * 1. open file 434 * 2. read filehdr 435 * 3. map text, data, and bss out of it using VM_* 436 */ 437 vp = epp->ep_interp; 438 if (vp == NULL) { 439 error = emul_find_interp(l, epp, path); 440 if (error != 0) 441 return error; 442 vp = epp->ep_interp; 443 } 444 /* We'll tidy this ourselves - otherwise we have locking issues */ 445 epp->ep_interp = NULL; 446 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 447 448 /* 449 * Similarly, if it's not marked as executable, or it's not a regular 450 * file, we don't allow it to be used. 451 */ 452 if (vp->v_type != VREG) { 453 error = EACCES; 454 goto badunlock; 455 } 456 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0) 457 goto badunlock; 458 459 /* get attributes */ 460 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0) 461 goto badunlock; 462 463 /* 464 * Check mount point. Though we're not trying to exec this binary, 465 * we will be executing code from it, so if the mount point 466 * disallows execution or set-id-ness, we punt or kill the set-id. 467 */ 468 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 469 error = EACCES; 470 goto badunlock; 471 } 472 if (vp->v_mount->mnt_flag & MNT_NOSUID) 473 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 474 475 #ifdef notyet /* XXX cgd 960926 */ 476 XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?) 477 478 XXXps: this problem will make it impossible to use an interpreter 479 from a file system which actually does something in VOP_OPEN 480 #endif 481 482 error = vn_marktext(vp); 483 if (error) 484 goto badunlock; 485 486 VOP_UNLOCK(vp); 487 488 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0) 489 goto bad; 490 491 if ((error = elf_check_header(&eh)) != 0) 492 goto bad; 493 if (eh.e_type != ET_DYN || eh.e_phnum == 0) { 494 error = ENOEXEC; 495 goto bad; 496 } 497 498 phsize = eh.e_phnum * sizeof(Elf_Phdr); 499 ph = kmem_alloc(phsize, KM_SLEEP); 500 501 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0) 502 goto bad; 503 504 #ifdef ELF_INTERP_NON_RELOCATABLE 505 /* 506 * Evil hack: Only MIPS should be non-relocatable, and the 507 * psections should have a high address (typically 0x5ffe0000). 508 * If it's now relocatable, it should be linked at 0 and the 509 * psections should have zeros in the upper part of the address. 510 * Otherwise, force the load at the linked address. 511 */ 512 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0) 513 *last = ELFDEFNNAME(NO_ADDR); 514 #endif 515 516 /* 517 * If no position to load the interpreter was set by a probe 518 * function, pick the same address that a non-fixed mmap(0, ..) 519 * would (i.e. something safely out of the way). 520 */ 521 if (*last == ELFDEFNNAME(NO_ADDR)) { 522 u_long limit = 0; 523 /* 524 * Find the start and ending addresses of the psections to 525 * be loaded. This will give us the size. 526 */ 527 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) { 528 if (ph[i].p_type == PT_LOAD) { 529 u_long psize = ph[i].p_vaddr + ph[i].p_memsz; 530 if (base_ph == NULL) 531 base_ph = &ph[i]; 532 if (psize > limit) 533 limit = psize; 534 } 535 } 536 537 if (base_ph == NULL) { 538 error = ENOEXEC; 539 goto bad; 540 } 541 542 /* 543 * Now compute the size and load address. 544 */ 545 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p, 546 epp->ep_daddr, 547 round_page(limit) - trunc_page(base_ph->p_vaddr)); 548 } else 549 addr = *last; /* may be ELF_LINK_ADDR */ 550 551 /* 552 * Load all the necessary sections 553 */ 554 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) { 555 switch (ph[i].p_type) { 556 case PT_LOAD: { 557 u_long size; 558 int flags; 559 560 if (base_ph == NULL) { 561 /* 562 * First encountered psection is always the 563 * base psection. Make sure it's aligned 564 * properly (align down for topdown and align 565 * upwards for not topdown). 566 */ 567 base_ph = &ph[i]; 568 flags = VMCMD_BASE; 569 if (addr == ELF_LINK_ADDR) 570 addr = ph[i].p_vaddr; 571 if (use_topdown) 572 addr = ELF_TRUNC(addr, ph[i].p_align); 573 else 574 addr = ELF_ROUND(addr, ph[i].p_align); 575 } else { 576 u_long limit = round_page(last_ph->p_vaddr 577 + last_ph->p_memsz); 578 u_long base = trunc_page(ph[i].p_vaddr); 579 580 /* 581 * If there is a gap in between the psections, 582 * map it as inaccessible so nothing else 583 * mmap'ed will be placed there. 584 */ 585 if (limit != base) { 586 NEW_VMCMD2(vcset, vmcmd_map_zero, 587 base - limit, 588 limit - base_ph->p_vaddr, NULLVP, 589 0, VM_PROT_NONE, VMCMD_RELATIVE); 590 } 591 592 addr = ph[i].p_vaddr - base_ph->p_vaddr; 593 flags = VMCMD_RELATIVE; 594 } 595 last_ph = &ph[i]; 596 elf_load_psection(vcset, vp, &ph[i], &addr, 597 &size, flags); 598 /* 599 * If entry is within this psection then this 600 * must contain the .text section. *entryoff is 601 * relative to the base psection. 602 */ 603 if (eh.e_entry >= ph[i].p_vaddr && 604 eh.e_entry < (ph[i].p_vaddr + size)) { 605 *entryoff = eh.e_entry - base_ph->p_vaddr; 606 } 607 addr += size; 608 break; 609 } 610 611 default: 612 break; 613 } 614 } 615 616 kmem_free(ph, phsize); 617 /* 618 * This value is ignored if TOPDOWN. 619 */ 620 *last = addr; 621 vrele(vp); 622 return 0; 623 624 badunlock: 625 VOP_UNLOCK(vp); 626 627 bad: 628 if (ph != NULL) 629 kmem_free(ph, phsize); 630 #ifdef notyet /* XXX cgd 960926 */ 631 (maybe) VOP_CLOSE it 632 #endif 633 vrele(vp); 634 return error; 635 } 636 637 /* 638 * exec_elf_makecmds(): Prepare an Elf binary's exec package 639 * 640 * First, set of the various offsets/lengths in the exec package. 641 * 642 * Then, mark the text image busy (so it can be demand paged) or error 643 * out if this is not possible. Finally, set up vmcmds for the 644 * text, data, bss, and stack segments. 645 */ 646 int 647 exec_elf_makecmds(struct lwp *l, struct exec_package *epp) 648 { 649 Elf_Ehdr *eh = epp->ep_hdr; 650 Elf_Phdr *ph, *pp; 651 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0; 652 int error, i; 653 char *interp = NULL; 654 u_long phsize; 655 struct elf_args *ap; 656 bool is_dyn = false; 657 658 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 659 return ENOEXEC; 660 if ((error = elf_check_header(eh)) != 0) 661 return error; 662 663 if (eh->e_type == ET_DYN) 664 /* 665 * XXX allow for executing shared objects. It seems silly 666 * but other ELF-based systems allow it as well. 667 */ 668 is_dyn = true; 669 else if (eh->e_type != ET_EXEC) 670 return ENOEXEC; 671 672 if (eh->e_phnum == 0) 673 return ENOEXEC; 674 675 error = vn_marktext(epp->ep_vp); 676 if (error) 677 return error; 678 679 /* 680 * Allocate space to hold all the program headers, and read them 681 * from the file 682 */ 683 phsize = eh->e_phnum * sizeof(Elf_Phdr); 684 ph = kmem_alloc(phsize, KM_SLEEP); 685 686 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) != 687 0) 688 goto bad; 689 690 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 691 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 692 693 for (i = 0; i < eh->e_phnum; i++) { 694 pp = &ph[i]; 695 if (pp->p_type == PT_INTERP) { 696 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) { 697 error = ENOEXEC; 698 goto bad; 699 } 700 interp = PNBUF_GET(); 701 if ((error = exec_read_from(l, epp->ep_vp, 702 pp->p_offset, interp, pp->p_filesz)) != 0) 703 goto bad; 704 /* Ensure interp is NUL-terminated and of the expected length */ 705 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) { 706 error = ENOEXEC; 707 goto bad; 708 } 709 break; 710 } 711 } 712 713 /* 714 * On the same architecture, we may be emulating different systems. 715 * See which one will accept this executable. 716 * 717 * Probe functions would normally see if the interpreter (if any) 718 * exists. Emulation packages may possibly replace the interpreter in 719 * interp[] with a changed path (/emul/xxx/<path>). 720 */ 721 pos = ELFDEFNNAME(NO_ADDR); 722 if (epp->ep_esch->u.elf_probe_func) { 723 vaddr_t startp = (vaddr_t)pos; 724 725 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp, 726 &startp); 727 if (error) 728 goto bad; 729 pos = (Elf_Addr)startp; 730 } 731 732 #if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR) 733 l->l_proc->p_pax = epp->ep_pax_flags; 734 #endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */ 735 736 if (is_dyn) 737 elf_placedynexec(l, epp, eh, ph); 738 739 /* 740 * Load all the necessary sections 741 */ 742 for (i = 0; i < eh->e_phnum; i++) { 743 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 744 u_long size = 0; 745 746 switch (ph[i].p_type) { 747 case PT_LOAD: 748 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 749 &ph[i], &addr, &size, VMCMD_FIXED); 750 751 /* 752 * Consider this as text segment, if it is executable. 753 * If there is more than one text segment, pick the 754 * largest. 755 */ 756 if (ph[i].p_flags & PF_X) { 757 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) || 758 size > epp->ep_tsize) { 759 epp->ep_taddr = addr; 760 epp->ep_tsize = size; 761 } 762 end_text = addr + size; 763 } else { 764 epp->ep_daddr = addr; 765 epp->ep_dsize = size; 766 } 767 if (ph[i].p_offset == 0) { 768 computed_phdr = ph[i].p_vaddr + eh->e_phoff; 769 } 770 break; 771 772 case PT_SHLIB: 773 /* SCO has these sections. */ 774 case PT_INTERP: 775 /* Already did this one. */ 776 case PT_DYNAMIC: 777 case PT_NOTE: 778 break; 779 case PT_PHDR: 780 /* Note address of program headers (in text segment) */ 781 phdr = ph[i].p_vaddr; 782 break; 783 784 default: 785 /* 786 * Not fatal; we don't need to understand everything. 787 */ 788 break; 789 } 790 } 791 792 if (epp->ep_vmcmds.evs_cmds == NULL) { 793 /* No VMCMD; there was no PT_LOAD section, or those 794 * sections were empty */ 795 error = ENOEXEC; 796 goto bad; 797 } 798 799 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 800 epp->ep_daddr = round_page(end_text); 801 epp->ep_dsize = 0; 802 } 803 804 /* 805 * Check if we found a dynamically linked binary and arrange to load 806 * its interpreter 807 */ 808 if (interp) { 809 u_int nused = epp->ep_vmcmds.evs_used; 810 u_long interp_offset = 0; 811 812 if ((error = elf_load_interp(l, epp, interp, 813 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) { 814 goto bad; 815 } 816 if (epp->ep_vmcmds.evs_used == nused) { 817 /* elf_load_interp() has not set up any new VMCMD */ 818 error = ENOEXEC; 819 goto bad; 820 } 821 822 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 823 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr; 824 epp->ep_entryoffset = interp_offset; 825 epp->ep_entry = ap->arg_interp + interp_offset; 826 PNBUF_PUT(interp); 827 } else { 828 epp->ep_entry = eh->e_entry; 829 if (epp->ep_flags & EXEC_FORCEAUX) { 830 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 831 ap->arg_interp = (vaddr_t)NULL; 832 } else 833 ap = NULL; 834 } 835 836 if (ap) { 837 ap->arg_phaddr = phdr ? phdr : computed_phdr; 838 ap->arg_phentsize = eh->e_phentsize; 839 ap->arg_phnum = eh->e_phnum; 840 ap->arg_entry = eh->e_entry; 841 epp->ep_emul_arg = ap; 842 epp->ep_emul_arg_free = elf_free_emul_arg; 843 } 844 845 #ifdef ELF_MAP_PAGE_ZERO 846 /* Dell SVR4 maps page zero, yeuch! */ 847 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0, 848 epp->ep_vp, 0, VM_PROT_READ); 849 #endif 850 kmem_free(ph, phsize); 851 return (*epp->ep_esch->es_setup_stack)(l, epp); 852 853 bad: 854 if (interp) 855 PNBUF_PUT(interp); 856 exec_free_emul_arg(epp); 857 kmem_free(ph, phsize); 858 kill_vmcmds(&epp->ep_vmcmds); 859 return error; 860 } 861 862 int 863 netbsd_elf_signature(struct lwp *l, struct exec_package *epp, 864 Elf_Ehdr *eh) 865 { 866 size_t i; 867 Elf_Shdr *sh; 868 Elf_Nhdr *np; 869 size_t shsize, nsize; 870 int error; 871 int isnetbsd = 0; 872 char *ndata, *ndesc; 873 #ifdef DIAGNOSTIC 874 const char *badnote; 875 #define BADNOTE(n) badnote = (n) 876 #else 877 #define BADNOTE(n) 878 #endif 879 880 epp->ep_pax_flags = 0; 881 if (eh->e_shnum > MAXSHNUM || eh->e_shnum == 0) 882 return ENOEXEC; 883 884 shsize = eh->e_shnum * sizeof(Elf_Shdr); 885 sh = kmem_alloc(shsize, KM_SLEEP); 886 error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize); 887 if (error) 888 goto out; 889 890 np = kmem_alloc(MAXNOTESIZE, KM_SLEEP); 891 for (i = 0; i < eh->e_shnum; i++) { 892 Elf_Shdr *shp = &sh[i]; 893 894 if (shp->sh_type != SHT_NOTE || 895 shp->sh_size > MAXNOTESIZE || 896 shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ) 897 continue; 898 899 error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np, 900 shp->sh_size); 901 if (error) 902 continue; 903 904 /* Point to the note, skip the header */ 905 ndata = (char *)(np + 1); 906 907 /* 908 * Padding is present if necessary to ensure 4-byte alignment. 909 * The actual section size is therefore: 910 * header size + 4-byte aligned name + 4-byte aligned desc 911 * Ensure this size is consistent with what is indicated 912 * in sh_size. The first check avoids integer overflows. 913 */ 914 if (np->n_namesz > shp->sh_size || np->n_descsz > shp->sh_size) { 915 BADNOTE("note size limit"); 916 goto bad; 917 } 918 nsize = sizeof(*np) + roundup(np->n_namesz, 4) + 919 roundup(np->n_descsz, 4); 920 if (nsize != shp->sh_size) { 921 BADNOTE("note size"); 922 goto bad; 923 } 924 ndesc = ndata + roundup(np->n_namesz, 4); 925 926 switch (np->n_type) { 927 case ELF_NOTE_TYPE_NETBSD_TAG: 928 /* It is us */ 929 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ && 930 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ && 931 memcmp(ndata, ELF_NOTE_NETBSD_NAME, 932 ELF_NOTE_NETBSD_NAMESZ) == 0) { 933 memcpy(&epp->ep_osversion, ndesc, 934 ELF_NOTE_NETBSD_DESCSZ); 935 isnetbsd = 1; 936 break; 937 } 938 939 /* 940 * Ignore SuSE tags; SuSE's n_type is the same as NetBSD's 941 * one. 942 */ 943 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ && 944 memcmp(ndata, ELF_NOTE_SUSE_NAME, 945 ELF_NOTE_SUSE_NAMESZ) == 0) 946 break; 947 BADNOTE("NetBSD tag"); 948 goto bad; 949 950 case ELF_NOTE_TYPE_PAX_TAG: 951 if (np->n_namesz == ELF_NOTE_PAX_NAMESZ && 952 np->n_descsz == ELF_NOTE_PAX_DESCSZ && 953 memcmp(ndata, ELF_NOTE_PAX_NAME, 954 ELF_NOTE_PAX_NAMESZ) == 0) { 955 memcpy(&epp->ep_pax_flags, ndesc, 956 sizeof(epp->ep_pax_flags)); 957 break; 958 } 959 BADNOTE("PaX tag"); 960 goto bad; 961 962 case ELF_NOTE_TYPE_MARCH_TAG: 963 /* Copy the machine arch into the package. */ 964 if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ 965 && memcmp(ndata, ELF_NOTE_MARCH_NAME, 966 ELF_NOTE_MARCH_NAMESZ) == 0) { 967 /* Do not truncate the buffer */ 968 if (np->n_descsz > sizeof(epp->ep_machine_arch)) { 969 BADNOTE("description size limit"); 970 goto bad; 971 } 972 /* 973 * Ensure ndesc is NUL-terminated and of the 974 * expected length. 975 */ 976 if (strnlen(ndesc, np->n_descsz) + 1 != 977 np->n_descsz) { 978 BADNOTE("description size"); 979 goto bad; 980 } 981 strlcpy(epp->ep_machine_arch, ndesc, 982 sizeof(epp->ep_machine_arch)); 983 break; 984 } 985 BADNOTE("march tag"); 986 goto bad; 987 988 case ELF_NOTE_TYPE_MCMODEL_TAG: 989 /* arch specific check for code model */ 990 #ifdef ELF_MD_MCMODEL_CHECK 991 if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ 992 && memcmp(ndata, ELF_NOTE_MCMODEL_NAME, 993 ELF_NOTE_MCMODEL_NAMESZ) == 0) { 994 ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz); 995 break; 996 } 997 BADNOTE("mcmodel tag"); 998 goto bad; 999 #endif 1000 break; 1001 1002 case ELF_NOTE_TYPE_SUSE_VERSION_TAG: 1003 break; 1004 1005 default: 1006 BADNOTE("unknown tag"); 1007 bad: 1008 #ifdef DIAGNOSTIC 1009 /* Ignore GNU tags */ 1010 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ && 1011 memcmp(ndata, ELF_NOTE_GNU_NAME, 1012 ELF_NOTE_GNU_NAMESZ) == 0) 1013 break; 1014 1015 int ns = MIN(np->n_namesz, shp->sh_size - sizeof(*np)); 1016 printf("%s: Unknown elf note type %d (%s): " 1017 "[namesz=%d, descsz=%d name=%-*.*s]\n", 1018 epp->ep_kname, np->n_type, badnote, np->n_namesz, 1019 np->n_descsz, ns, ns, ndata); 1020 #endif 1021 break; 1022 } 1023 } 1024 kmem_free(np, MAXNOTESIZE); 1025 1026 error = isnetbsd ? 0 : ENOEXEC; 1027 out: 1028 kmem_free(sh, shsize); 1029 return error; 1030 } 1031 1032 int 1033 netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp, 1034 vaddr_t *pos) 1035 { 1036 int error; 1037 1038 if ((error = netbsd_elf_signature(l, epp, eh)) != 0) 1039 return error; 1040 #ifdef ELF_MD_PROBE_FUNC 1041 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0) 1042 return error; 1043 #elif defined(ELF_INTERP_NON_RELOCATABLE) 1044 *pos = ELF_LINK_ADDR; 1045 #endif 1046 epp->ep_flags |= EXEC_FORCEAUX; 1047 return 0; 1048 } 1049 1050 void 1051 elf_free_emul_arg(void *arg) 1052 { 1053 struct elf_args *ap = arg; 1054 KASSERT(ap != NULL); 1055 kmem_free(ap, sizeof(*ap)); 1056 } 1057