1 /* $NetBSD: exec_elf.c,v 1.70 2014/08/17 23:03:58 chs 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 1.70 2014/08/17 23:03:58 chs 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 lwp *l, struct exec_package *epp, Elf_Ehdr *eh, 120 Elf_Phdr *ph) 121 { 122 Elf_Addr align, offset; 123 int i; 124 125 for (align = i = 0; i < eh->e_phnum; i++) 126 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align) 127 align = ph[i].p_align; 128 129 #ifdef PAX_ASLR 130 if (pax_aslr_active(l)) { 131 size_t pax_align, l2, delta; 132 uint32_t r; 133 134 pax_align = align; 135 136 r = cprng_fast32(); 137 138 if (pax_align == 0) 139 pax_align = PGSHIFT; 140 l2 = ilog2(pax_align); 141 delta = PAX_ASLR_DELTA(r, l2, PAX_ASLR_DELTA_EXEC_LEN); 142 offset = ELF_TRUNC(delta, pax_align) + PAGE_SIZE; 143 #ifdef PAX_ASLR_DEBUG 144 uprintf("r=0x%x l2=0x%zx PGSHIFT=0x%x Delta=0x%zx\n", r, l2, 145 PGSHIFT, delta); 146 uprintf("pax offset=0x%llx entry=0x%llx\n", 147 (unsigned long long)offset, 148 (unsigned long long)eh->e_entry); 149 #endif /* PAX_ASLR_DEBUG */ 150 } else 151 #endif /* PAX_ASLR */ 152 offset = MAX(align, PAGE_SIZE); 153 154 offset += epp->ep_vm_minaddr; 155 156 for (i = 0; i < eh->e_phnum; i++) 157 ph[i].p_vaddr += offset; 158 epp->ep_entryoffset = offset; 159 eh->e_entry += offset; 160 } 161 162 /* 163 * Copy arguments onto the stack in the normal way, but add some 164 * extra information in case of dynamic binding. 165 */ 166 int 167 elf_copyargs(struct lwp *l, struct exec_package *pack, 168 struct ps_strings *arginfo, char **stackp, void *argp) 169 { 170 size_t len, vlen; 171 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname; 172 struct elf_args *ap; 173 int error; 174 175 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0) 176 return error; 177 178 a = ai; 179 execname = NULL; 180 181 /* 182 * Push extra arguments on the stack needed by dynamically 183 * linked binaries 184 */ 185 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 186 struct vattr *vap = pack->ep_vap; 187 188 a->a_type = AT_PHDR; 189 a->a_v = ap->arg_phaddr; 190 a++; 191 192 a->a_type = AT_PHENT; 193 a->a_v = ap->arg_phentsize; 194 a++; 195 196 a->a_type = AT_PHNUM; 197 a->a_v = ap->arg_phnum; 198 a++; 199 200 a->a_type = AT_PAGESZ; 201 a->a_v = PAGE_SIZE; 202 a++; 203 204 a->a_type = AT_BASE; 205 a->a_v = ap->arg_interp; 206 a++; 207 208 a->a_type = AT_FLAGS; 209 a->a_v = 0; 210 a++; 211 212 a->a_type = AT_ENTRY; 213 a->a_v = ap->arg_entry; 214 a++; 215 216 a->a_type = AT_EUID; 217 if (vap->va_mode & S_ISUID) 218 a->a_v = vap->va_uid; 219 else 220 a->a_v = kauth_cred_geteuid(l->l_cred); 221 a++; 222 223 a->a_type = AT_RUID; 224 a->a_v = kauth_cred_getuid(l->l_cred); 225 a++; 226 227 a->a_type = AT_EGID; 228 if (vap->va_mode & S_ISGID) 229 a->a_v = vap->va_gid; 230 else 231 a->a_v = kauth_cred_getegid(l->l_cred); 232 a++; 233 234 a->a_type = AT_RGID; 235 a->a_v = kauth_cred_getgid(l->l_cred); 236 a++; 237 238 a->a_type = AT_STACKBASE; 239 a->a_v = l->l_proc->p_stackbase; 240 a++; 241 242 if (pack->ep_path) { 243 execname = a; 244 a->a_type = AT_SUN_EXECNAME; 245 a++; 246 } 247 248 exec_free_emul_arg(pack); 249 } 250 251 a->a_type = AT_NULL; 252 a->a_v = 0; 253 a++; 254 255 vlen = (a - ai) * sizeof(ai[0]); 256 257 KASSERT(vlen <= sizeof(ai)); 258 259 if (execname) { 260 char *path = pack->ep_path; 261 execname->a_v = (uintptr_t)(*stackp + vlen); 262 len = strlen(path) + 1; 263 if ((error = copyout(path, (*stackp + vlen), len)) != 0) 264 return error; 265 len = ALIGN(len); 266 } else 267 len = 0; 268 269 if ((error = copyout(ai, *stackp, vlen)) != 0) 270 return error; 271 *stackp += vlen + len; 272 273 return 0; 274 } 275 276 /* 277 * elf_check_header(): 278 * 279 * Check header for validity; return 0 if ok, ENOEXEC if error 280 */ 281 int 282 elf_check_header(Elf_Ehdr *eh) 283 { 284 285 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 || 286 eh->e_ident[EI_CLASS] != ELFCLASS) 287 return ENOEXEC; 288 289 switch (eh->e_machine) { 290 291 ELFDEFNNAME(MACHDEP_ID_CASES) 292 293 default: 294 return ENOEXEC; 295 } 296 297 if (ELF_EHDR_FLAGS_OK(eh) == 0) 298 return ENOEXEC; 299 300 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM) 301 return ENOEXEC; 302 303 return 0; 304 } 305 306 /* 307 * elf_load_psection(): 308 * 309 * Load a psection at the appropriate address 310 */ 311 static void 312 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp, 313 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags) 314 { 315 u_long msize, psize, rm, rf; 316 long diff, offset; 317 int vmprot = 0; 318 319 /* 320 * If the user specified an address, then we load there. 321 */ 322 if (*addr == ELFDEFNNAME(NO_ADDR)) 323 *addr = ph->p_vaddr; 324 325 if (ph->p_align > 1) { 326 /* 327 * Make sure we are virtually aligned as we are supposed to be. 328 */ 329 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align); 330 KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align)); 331 /* 332 * But make sure to not map any pages before the start of the 333 * psection by limiting the difference to within a page. 334 */ 335 diff &= PAGE_MASK; 336 } else 337 diff = 0; 338 339 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; 340 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; 341 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; 342 343 /* 344 * Adjust everything so it all starts on a page boundary. 345 */ 346 *addr -= diff; 347 offset = ph->p_offset - diff; 348 *size = ph->p_filesz + diff; 349 msize = ph->p_memsz + diff; 350 351 if (ph->p_align >= PAGE_SIZE) { 352 if ((ph->p_flags & PF_W) != 0) { 353 /* 354 * Because the pagedvn pager can't handle zero fill 355 * of the last data page if it's not page aligned we 356 * map the last page readvn. 357 */ 358 psize = trunc_page(*size); 359 } else { 360 psize = round_page(*size); 361 } 362 } else { 363 psize = *size; 364 } 365 366 if (psize > 0) { 367 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ? 368 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp, 369 offset, vmprot, flags); 370 flags &= VMCMD_RELATIVE; 371 } 372 if (psize < *size) { 373 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize, 374 *addr + psize, vp, offset + psize, vmprot, flags); 375 } 376 377 /* 378 * Check if we need to extend the size of the segment (does 379 * bss extend page the next page boundary)? 380 */ 381 rm = round_page(*addr + msize); 382 rf = round_page(*addr + *size); 383 384 if (rm != rf) { 385 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 386 0, vmprot, flags & VMCMD_RELATIVE); 387 *size = msize; 388 } 389 } 390 391 /* 392 * elf_load_interp(): 393 * 394 * Load an interpreter pointed to by path. 395 */ 396 static int 397 elf_load_interp(struct lwp *l, struct exec_package *epp, char *path, 398 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last) 399 { 400 int error, i; 401 struct vnode *vp; 402 struct vattr attr; 403 Elf_Ehdr eh; 404 Elf_Phdr *ph = NULL; 405 const Elf_Phdr *base_ph; 406 const Elf_Phdr *last_ph; 407 u_long phsize; 408 Elf_Addr addr = *last; 409 struct proc *p; 410 bool use_topdown; 411 412 p = l->l_proc; 413 414 KASSERT(p->p_vmspace); 415 if (__predict_true(p->p_vmspace != proc0.p_vmspace)) { 416 use_topdown = p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN; 417 } else { 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 /* 426 * 1. open file 427 * 2. read filehdr 428 * 3. map text, data, and bss out of it using VM_* 429 */ 430 vp = epp->ep_interp; 431 if (vp == NULL) { 432 error = emul_find_interp(l, epp, path); 433 if (error != 0) 434 return error; 435 vp = epp->ep_interp; 436 } 437 /* We'll tidy this ourselves - otherwise we have locking issues */ 438 epp->ep_interp = NULL; 439 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 440 441 /* 442 * Similarly, if it's not marked as executable, or it's not a regular 443 * file, we don't allow it to be used. 444 */ 445 if (vp->v_type != VREG) { 446 error = EACCES; 447 goto badunlock; 448 } 449 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0) 450 goto badunlock; 451 452 /* get attributes */ 453 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0) 454 goto badunlock; 455 456 /* 457 * Check mount point. Though we're not trying to exec this binary, 458 * we will be executing code from it, so if the mount point 459 * disallows execution or set-id-ness, we punt or kill the set-id. 460 */ 461 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 462 error = EACCES; 463 goto badunlock; 464 } 465 if (vp->v_mount->mnt_flag & MNT_NOSUID) 466 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 467 468 #ifdef notyet /* XXX cgd 960926 */ 469 XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?) 470 471 XXXps: this problem will make it impossible to use an interpreter 472 from a file system which actually does something in VOP_OPEN 473 #endif 474 475 error = vn_marktext(vp); 476 if (error) 477 goto badunlock; 478 479 VOP_UNLOCK(vp); 480 481 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0) 482 goto bad; 483 484 if ((error = elf_check_header(&eh)) != 0) 485 goto bad; 486 if (eh.e_type != ET_DYN || eh.e_phnum == 0) { 487 error = ENOEXEC; 488 goto bad; 489 } 490 491 phsize = eh.e_phnum * sizeof(Elf_Phdr); 492 ph = kmem_alloc(phsize, KM_SLEEP); 493 494 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0) 495 goto bad; 496 497 #ifdef ELF_INTERP_NON_RELOCATABLE 498 /* 499 * Evil hack: Only MIPS should be non-relocatable, and the 500 * psections should have a high address (typically 0x5ffe0000). 501 * If it's now relocatable, it should be linked at 0 and the 502 * psections should have zeros in the upper part of the address. 503 * Otherwise, force the load at the linked address. 504 */ 505 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0) 506 *last = ELFDEFNNAME(NO_ADDR); 507 #endif 508 509 /* 510 * If no position to load the interpreter was set by a probe 511 * function, pick the same address that a non-fixed mmap(0, ..) 512 * would (i.e. something safely out of the way). 513 */ 514 if (*last == ELFDEFNNAME(NO_ADDR)) { 515 u_long limit = 0; 516 /* 517 * Find the start and ending addresses of the psections to 518 * be loaded. This will give us the size. 519 */ 520 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) { 521 if (ph[i].p_type == PT_LOAD) { 522 u_long psize = ph[i].p_vaddr + ph[i].p_memsz; 523 if (base_ph == NULL) 524 base_ph = &ph[i]; 525 if (psize > limit) 526 limit = psize; 527 } 528 } 529 530 if (base_ph == NULL) { 531 error = ENOEXEC; 532 goto bad; 533 } 534 535 /* 536 * Now compute the size and load address. 537 */ 538 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p, 539 epp->ep_daddr, 540 round_page(limit) - trunc_page(base_ph->p_vaddr)); 541 } else 542 addr = *last; /* may be ELF_LINK_ADDR */ 543 544 /* 545 * Load all the necessary sections 546 */ 547 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) { 548 switch (ph[i].p_type) { 549 case PT_LOAD: { 550 u_long size; 551 int flags; 552 553 if (base_ph == NULL) { 554 /* 555 * First encountered psection is always the 556 * base psection. Make sure it's aligned 557 * properly (align down for topdown and align 558 * upwards for not topdown). 559 */ 560 base_ph = &ph[i]; 561 flags = VMCMD_BASE; 562 if (addr == ELF_LINK_ADDR) 563 addr = ph[i].p_vaddr; 564 if (use_topdown) 565 addr = ELF_TRUNC(addr, ph[i].p_align); 566 else 567 addr = ELF_ROUND(addr, ph[i].p_align); 568 } else { 569 u_long limit = round_page(last_ph->p_vaddr 570 + last_ph->p_memsz); 571 u_long base = trunc_page(ph[i].p_vaddr); 572 573 /* 574 * If there is a gap in between the psections, 575 * map it as inaccessible so nothing else 576 * mmap'ed will be placed there. 577 */ 578 if (limit != base) { 579 NEW_VMCMD2(vcset, vmcmd_map_zero, 580 base - limit, 581 limit - base_ph->p_vaddr, NULLVP, 582 0, VM_PROT_NONE, VMCMD_RELATIVE); 583 } 584 585 addr = ph[i].p_vaddr - base_ph->p_vaddr; 586 flags = VMCMD_RELATIVE; 587 } 588 last_ph = &ph[i]; 589 elf_load_psection(vcset, vp, &ph[i], &addr, 590 &size, flags); 591 /* 592 * If entry is within this psection then this 593 * must contain the .text section. *entryoff is 594 * relative to the base psection. 595 */ 596 if (eh.e_entry >= ph[i].p_vaddr && 597 eh.e_entry < (ph[i].p_vaddr + size)) { 598 *entryoff = eh.e_entry - base_ph->p_vaddr; 599 } 600 addr += size; 601 break; 602 } 603 604 default: 605 break; 606 } 607 } 608 609 kmem_free(ph, phsize); 610 /* 611 * This value is ignored if TOPDOWN. 612 */ 613 *last = addr; 614 vrele(vp); 615 return 0; 616 617 badunlock: 618 VOP_UNLOCK(vp); 619 620 bad: 621 if (ph != NULL) 622 kmem_free(ph, phsize); 623 #ifdef notyet /* XXX cgd 960926 */ 624 (maybe) VOP_CLOSE it 625 #endif 626 vrele(vp); 627 return error; 628 } 629 630 /* 631 * exec_elf_makecmds(): Prepare an Elf binary's exec package 632 * 633 * First, set of the various offsets/lengths in the exec package. 634 * 635 * Then, mark the text image busy (so it can be demand paged) or error 636 * out if this is not possible. Finally, set up vmcmds for the 637 * text, data, bss, and stack segments. 638 */ 639 int 640 exec_elf_makecmds(struct lwp *l, struct exec_package *epp) 641 { 642 Elf_Ehdr *eh = epp->ep_hdr; 643 Elf_Phdr *ph, *pp; 644 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0; 645 int error, i; 646 char *interp = NULL; 647 u_long phsize; 648 struct elf_args *ap; 649 bool is_dyn = false; 650 651 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 652 return ENOEXEC; 653 if ((error = elf_check_header(eh)) != 0) 654 return error; 655 656 if (eh->e_type == ET_DYN) 657 /* 658 * XXX allow for executing shared objects. It seems silly 659 * but other ELF-based systems allow it as well. 660 */ 661 is_dyn = true; 662 else if (eh->e_type != ET_EXEC) 663 return ENOEXEC; 664 665 if (eh->e_phnum == 0) 666 return ENOEXEC; 667 668 error = vn_marktext(epp->ep_vp); 669 if (error) 670 return error; 671 672 /* 673 * Allocate space to hold all the program headers, and read them 674 * from the file 675 */ 676 phsize = eh->e_phnum * sizeof(Elf_Phdr); 677 ph = kmem_alloc(phsize, KM_SLEEP); 678 679 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) != 680 0) 681 goto bad; 682 683 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 684 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 685 686 for (i = 0; i < eh->e_phnum; i++) { 687 pp = &ph[i]; 688 if (pp->p_type == PT_INTERP) { 689 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) { 690 error = ENOEXEC; 691 goto bad; 692 } 693 interp = PNBUF_GET(); 694 if ((error = exec_read_from(l, epp->ep_vp, 695 pp->p_offset, interp, pp->p_filesz)) != 0) 696 goto bad; 697 /* Ensure interp is NUL-terminated and of the expected length */ 698 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) { 699 error = ENOEXEC; 700 goto bad; 701 } 702 break; 703 } 704 } 705 706 /* 707 * On the same architecture, we may be emulating different systems. 708 * See which one will accept this executable. 709 * 710 * Probe functions would normally see if the interpreter (if any) 711 * exists. Emulation packages may possibly replace the interpreter in 712 * interp[] with a changed path (/emul/xxx/<path>). 713 */ 714 pos = ELFDEFNNAME(NO_ADDR); 715 if (epp->ep_esch->u.elf_probe_func) { 716 vaddr_t startp = (vaddr_t)pos; 717 718 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp, 719 &startp); 720 if (error) 721 goto bad; 722 pos = (Elf_Addr)startp; 723 } 724 725 #if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR) 726 l->l_proc->p_pax = epp->ep_pax_flags; 727 #endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */ 728 729 if (is_dyn) 730 elf_placedynexec(l, epp, eh, ph); 731 732 /* 733 * Load all the necessary sections 734 */ 735 for (i = 0; i < eh->e_phnum; i++) { 736 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 737 u_long size = 0; 738 739 switch (ph[i].p_type) { 740 case PT_LOAD: 741 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 742 &ph[i], &addr, &size, VMCMD_FIXED); 743 744 /* 745 * Consider this as text segment, if it is executable. 746 * If there is more than one text segment, pick the 747 * largest. 748 */ 749 if (ph[i].p_flags & PF_X) { 750 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) || 751 size > epp->ep_tsize) { 752 epp->ep_taddr = addr; 753 epp->ep_tsize = size; 754 } 755 end_text = addr + size; 756 } else { 757 epp->ep_daddr = addr; 758 epp->ep_dsize = size; 759 } 760 if (ph[i].p_offset == 0) { 761 computed_phdr = ph[i].p_vaddr + eh->e_phoff; 762 } 763 break; 764 765 case PT_SHLIB: 766 /* SCO has these sections. */ 767 case PT_INTERP: 768 /* Already did this one. */ 769 case PT_DYNAMIC: 770 case PT_NOTE: 771 break; 772 case PT_PHDR: 773 /* Note address of program headers (in text segment) */ 774 phdr = ph[i].p_vaddr; 775 break; 776 777 default: 778 /* 779 * Not fatal; we don't need to understand everything. 780 */ 781 break; 782 } 783 } 784 785 if (epp->ep_vmcmds.evs_used == 0) { 786 /* No VMCMD; there was no PT_LOAD section, or those 787 * sections were empty */ 788 error = ENOEXEC; 789 goto bad; 790 } 791 792 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 793 epp->ep_daddr = round_page(end_text); 794 epp->ep_dsize = 0; 795 } 796 797 /* 798 * Check if we found a dynamically linked binary and arrange to load 799 * its interpreter 800 */ 801 if (interp) { 802 u_int nused = epp->ep_vmcmds.evs_used; 803 u_long interp_offset = 0; 804 805 if ((error = elf_load_interp(l, epp, interp, 806 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) { 807 goto bad; 808 } 809 if (epp->ep_vmcmds.evs_used == nused) { 810 /* elf_load_interp() has not set up any new VMCMD */ 811 error = ENOEXEC; 812 goto bad; 813 } 814 815 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 816 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr; 817 epp->ep_entryoffset = interp_offset; 818 epp->ep_entry = ap->arg_interp + interp_offset; 819 PNBUF_PUT(interp); 820 } else { 821 epp->ep_entry = eh->e_entry; 822 if (epp->ep_flags & EXEC_FORCEAUX) { 823 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 824 ap->arg_interp = (vaddr_t)NULL; 825 } else 826 ap = NULL; 827 } 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, nsize; 863 int error; 864 int isnetbsd = 0; 865 char *ndata, *ndesc; 866 867 #ifdef DIAGNOSTIC 868 const char *badnote; 869 #define BADNOTE(n) badnote = (n) 870 #else 871 #define BADNOTE(n) 872 #endif 873 874 epp->ep_pax_flags = 0; 875 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_shnum == 0) 876 return ENOEXEC; 877 878 shsize = eh->e_shnum * sizeof(Elf_Shdr); 879 sh = kmem_alloc(shsize, KM_SLEEP); 880 error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize); 881 if (error) 882 goto out; 883 884 np = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP); 885 for (i = 0; i < eh->e_shnum; i++) { 886 Elf_Shdr *shp = &sh[i]; 887 888 if (shp->sh_type != SHT_NOTE || 889 shp->sh_size > ELF_MAXNOTESIZE || 890 shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ) 891 continue; 892 893 error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np, 894 shp->sh_size); 895 if (error) 896 continue; 897 898 /* Point to the note, skip the header */ 899 ndata = (char *)(np + 1); 900 901 /* 902 * Padding is present if necessary to ensure 4-byte alignment. 903 * The actual section size is therefore: 904 * header size + 4-byte aligned name + 4-byte aligned desc 905 * Ensure this size is consistent with what is indicated 906 * in sh_size. The first check avoids integer overflows. 907 * 908 * Binaries from before NetBSD 1.6 have two notes in the same 909 * note section. The second note was never used, so as long as 910 * the section is at least as big as it should be, it's ok. 911 * These binaries also have a second note section with a note of 912 * type ELF_NOTE_TYPE_NETBSD_TAG, which can be ignored as well. 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, ELF_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