1 /* $NetBSD: exec_elf.c,v 1.100 2019/09/16 11:11:34 christos 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 1.100 2019/09/16 11:11:34 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 80 #include <sys/cpu.h> 81 #include <machine/reg.h> 82 83 #include <compat/common/compat_util.h> 84 85 #include <sys/pax.h> 86 #include <uvm/uvm_param.h> 87 88 extern struct emul emul_netbsd; 89 90 #define elf_check_header ELFNAME(check_header) 91 #define elf_copyargs ELFNAME(copyargs) 92 #define elf_populate_auxv ELFNAME(populate_auxv) 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_note ELFNAME2(netbsd,note) 98 #define netbsd_elf_probe ELFNAME2(netbsd,probe) 99 #define coredump ELFNAMEEND(coredump) 100 #define elf_free_emul_arg ELFNAME(free_emul_arg) 101 102 static int 103 elf_load_interp(struct lwp *, struct exec_package *, char *, 104 struct exec_vmcmd_set *, u_long *, Elf_Addr *); 105 static int 106 elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *, 107 Elf_Addr *, u_long *, int); 108 109 int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *); 110 int netbsd_elf_note(struct exec_package *, const Elf_Nhdr *, const char *, 111 const char *); 112 int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *, 113 vaddr_t *); 114 115 static void elf_free_emul_arg(void *); 116 117 #ifdef DEBUG_ELF 118 #define DPRINTF(a, ...) printf("%s: " a "\n", __func__, ##__VA_ARGS__) 119 #else 120 #define DPRINTF(a, ...) 121 #endif 122 123 /* round up and down to page boundaries. */ 124 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 125 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1)) 126 127 static int 128 elf_placedynexec(struct exec_package *epp, Elf_Ehdr *eh, Elf_Phdr *ph) 129 { 130 Elf_Addr align, offset; 131 int i; 132 133 for (align = 1, i = 0; i < eh->e_phnum; i++) 134 if (ph[i].p_type == PT_LOAD && ph[i].p_align > align) 135 align = ph[i].p_align; 136 137 offset = (Elf_Addr)pax_aslr_exec_offset(epp, align); 138 if (offset < epp->ep_vm_minaddr) 139 offset = roundup(epp->ep_vm_minaddr, align); 140 if ((offset & (align - 1)) != 0) { 141 DPRINTF("bad offset=%#jx align=%#jx", 142 (uintmax_t)offset, (uintmax_t)align); 143 return EINVAL; 144 } 145 146 for (i = 0; i < eh->e_phnum; i++) 147 ph[i].p_vaddr += offset; 148 epp->ep_entryoffset = offset; 149 eh->e_entry += offset; 150 return 0; 151 } 152 153 154 int 155 elf_populate_auxv(struct lwp *l, struct exec_package *pack, char **stackp) 156 { 157 size_t len, vlen; 158 AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname; 159 struct elf_args *ap; 160 char *path = l->l_proc->p_path; 161 int error; 162 163 execname = NULL; 164 a = ai; 165 166 memset(ai, 0, sizeof(ai)); 167 168 /* 169 * Push extra arguments on the stack needed by dynamically 170 * linked binaries 171 */ 172 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 173 struct vattr *vap = pack->ep_vap; 174 175 a->a_type = AT_PHDR; 176 a->a_v = ap->arg_phaddr; 177 a++; 178 179 a->a_type = AT_PHENT; 180 a->a_v = ap->arg_phentsize; 181 a++; 182 183 a->a_type = AT_PHNUM; 184 a->a_v = ap->arg_phnum; 185 a++; 186 187 a->a_type = AT_PAGESZ; 188 a->a_v = PAGE_SIZE; 189 a++; 190 191 a->a_type = AT_BASE; 192 a->a_v = ap->arg_interp; 193 a++; 194 195 a->a_type = AT_FLAGS; 196 a->a_v = 0; 197 a++; 198 199 a->a_type = AT_ENTRY; 200 a->a_v = ap->arg_entry; 201 a++; 202 203 a->a_type = AT_EUID; 204 if (vap->va_mode & S_ISUID) 205 a->a_v = vap->va_uid; 206 else 207 a->a_v = kauth_cred_geteuid(l->l_cred); 208 a++; 209 210 a->a_type = AT_RUID; 211 a->a_v = kauth_cred_getuid(l->l_cred); 212 a++; 213 214 a->a_type = AT_EGID; 215 if (vap->va_mode & S_ISGID) 216 a->a_v = vap->va_gid; 217 else 218 a->a_v = kauth_cred_getegid(l->l_cred); 219 a++; 220 221 a->a_type = AT_RGID; 222 a->a_v = kauth_cred_getgid(l->l_cred); 223 a++; 224 225 a->a_type = AT_STACKBASE; 226 a->a_v = l->l_proc->p_stackbase; 227 a++; 228 229 /* "/" means fexecve(2) could not resolve the pathname */ 230 if (path[0] == '/' && path[1] != '\0') { 231 execname = a; 232 a->a_type = AT_SUN_EXECNAME; 233 a++; 234 } 235 236 exec_free_emul_arg(pack); 237 } 238 239 a->a_type = AT_NULL; 240 a->a_v = 0; 241 a++; 242 243 vlen = (a - ai) * sizeof(ai[0]); 244 245 KASSERT(vlen <= sizeof(ai)); 246 247 if (execname) { 248 execname->a_v = (uintptr_t)(*stackp + vlen); 249 len = strlen(path) + 1; 250 if ((error = copyout(path, (*stackp + vlen), len)) != 0) 251 return error; 252 len = ALIGN(len); 253 } else { 254 len = 0; 255 } 256 257 if ((error = copyout(ai, *stackp, vlen)) != 0) 258 return error; 259 *stackp += vlen + len; 260 261 return 0; 262 } 263 264 /* 265 * Copy arguments onto the stack in the normal way, but add some 266 * extra information in case of dynamic binding. 267 */ 268 int 269 elf_copyargs(struct lwp *l, struct exec_package *pack, 270 struct ps_strings *arginfo, char **stackp, void *argp) 271 { 272 int error; 273 274 if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0) 275 return error; 276 277 return elf_populate_auxv(l, pack, stackp); 278 } 279 280 /* 281 * elf_check_header(): 282 * 283 * Check header for validity; return 0 if ok, ENOEXEC if error 284 */ 285 int 286 elf_check_header(Elf_Ehdr *eh) 287 { 288 289 if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 || 290 eh->e_ident[EI_CLASS] != ELFCLASS) { 291 DPRINTF("bad magic e_ident[EI_MAG0,EI_MAG3] %#x%x%x%x, " 292 "e_ident[EI_CLASS] %#x", eh->e_ident[EI_MAG0], 293 eh->e_ident[EI_MAG1], eh->e_ident[EI_MAG2], 294 eh->e_ident[EI_MAG3], eh->e_ident[EI_CLASS]); 295 return ENOEXEC; 296 } 297 298 switch (eh->e_machine) { 299 300 ELFDEFNNAME(MACHDEP_ID_CASES) 301 302 default: 303 DPRINTF("bad machine %#x", eh->e_machine); 304 return ENOEXEC; 305 } 306 307 if (ELF_EHDR_FLAGS_OK(eh) == 0) { 308 DPRINTF("bad flags %#x", eh->e_flags); 309 return ENOEXEC; 310 } 311 312 if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM) { 313 DPRINTF("bad shnum/phnum %#x/%#x", eh->e_shnum, eh->e_phnum); 314 return ENOEXEC; 315 } 316 317 return 0; 318 } 319 320 /* 321 * elf_load_psection(): 322 * 323 * Load a psection at the appropriate address 324 */ 325 static int 326 elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp, 327 const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags) 328 { 329 u_long msize, psize, rm, rf; 330 long diff, offset; 331 int vmprot = 0; 332 333 /* 334 * If the user specified an address, then we load there. 335 */ 336 if (*addr == ELFDEFNNAME(NO_ADDR)) 337 *addr = ph->p_vaddr; 338 339 if (ph->p_align > 1) { 340 /* 341 * Make sure we are virtually aligned as we are supposed to be. 342 */ 343 diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align); 344 if (*addr - diff != ELF_TRUNC(*addr, ph->p_align)) { 345 DPRINTF("bad alignment %#jx != %#jx\n", 346 (uintptr_t)(*addr - diff), 347 (uintptr_t)ELF_TRUNC(*addr, ph->p_align)); 348 return EINVAL; 349 } 350 /* 351 * But make sure to not map any pages before the start of the 352 * psection by limiting the difference to within a page. 353 */ 354 diff &= PAGE_MASK; 355 } else 356 diff = 0; 357 358 vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0; 359 vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0; 360 vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0; 361 362 /* 363 * Adjust everything so it all starts on a page boundary. 364 */ 365 *addr -= diff; 366 offset = ph->p_offset - diff; 367 *size = ph->p_filesz + diff; 368 msize = ph->p_memsz + diff; 369 370 if (ph->p_align >= PAGE_SIZE) { 371 if ((ph->p_flags & PF_W) != 0) { 372 /* 373 * Because the pagedvn pager can't handle zero fill 374 * of the last data page if it's not page aligned we 375 * map the last page readvn. 376 */ 377 psize = trunc_page(*size); 378 } else { 379 psize = round_page(*size); 380 } 381 } else { 382 psize = *size; 383 } 384 385 if (psize > 0) { 386 NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ? 387 vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp, 388 offset, vmprot, flags); 389 flags &= VMCMD_RELATIVE; 390 } 391 if (psize < *size) { 392 NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize, 393 *addr + psize, vp, offset + psize, vmprot, flags); 394 } 395 396 /* 397 * Check if we need to extend the size of the segment (does 398 * bss extend page the next page boundary)? 399 */ 400 rm = round_page(*addr + msize); 401 rf = round_page(*addr + *size); 402 403 if (rm != rf) { 404 NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 405 0, vmprot, flags & VMCMD_RELATIVE); 406 *size = msize; 407 } 408 return 0; 409 } 410 411 /* 412 * elf_load_interp(): 413 * 414 * Load an interpreter pointed to by path. 415 */ 416 static int 417 elf_load_interp(struct lwp *l, struct exec_package *epp, char *path, 418 struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last) 419 { 420 int error, i; 421 struct vnode *vp; 422 struct vattr attr; 423 Elf_Ehdr eh; 424 Elf_Phdr *ph = NULL; 425 const Elf_Phdr *base_ph; 426 const Elf_Phdr *last_ph; 427 u_long phsize; 428 Elf_Addr addr = *last; 429 struct proc *p; 430 bool use_topdown; 431 432 p = l->l_proc; 433 434 KASSERT(p->p_vmspace); 435 KASSERT(p->p_vmspace != proc0.p_vmspace); 436 437 #ifdef __USE_TOPDOWN_VM 438 use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM; 439 #else 440 use_topdown = false; 441 #endif 442 443 /* 444 * 1. open file 445 * 2. read filehdr 446 * 3. map text, data, and bss out of it using VM_* 447 */ 448 vp = epp->ep_interp; 449 if (vp == NULL) { 450 error = emul_find_interp(l, epp, path); 451 if (error != 0) 452 return error; 453 vp = epp->ep_interp; 454 } 455 /* We'll tidy this ourselves - otherwise we have locking issues */ 456 epp->ep_interp = NULL; 457 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 458 459 /* 460 * Similarly, if it's not marked as executable, or it's not a regular 461 * file, we don't allow it to be used. 462 */ 463 if (vp->v_type != VREG) { 464 error = EACCES; 465 goto badunlock; 466 } 467 if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0) 468 goto badunlock; 469 470 /* get attributes */ 471 if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0) 472 goto badunlock; 473 474 /* 475 * Check mount point. Though we're not trying to exec this binary, 476 * we will be executing code from it, so if the mount point 477 * disallows execution or set-id-ness, we punt or kill the set-id. 478 */ 479 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 480 error = EACCES; 481 goto badunlock; 482 } 483 if (vp->v_mount->mnt_flag & MNT_NOSUID) 484 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 485 486 error = vn_marktext(vp); 487 if (error) 488 goto badunlock; 489 490 VOP_UNLOCK(vp); 491 492 if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0) 493 goto bad; 494 495 if ((error = elf_check_header(&eh)) != 0) 496 goto bad; 497 if (eh.e_type != ET_DYN || eh.e_phnum == 0) { 498 DPRINTF("bad interpreter type %#x", eh.e_type); 499 error = ENOEXEC; 500 goto bad; 501 } 502 503 phsize = eh.e_phnum * sizeof(Elf_Phdr); 504 ph = kmem_alloc(phsize, KM_SLEEP); 505 506 if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0) 507 goto bad; 508 509 #ifdef ELF_INTERP_NON_RELOCATABLE 510 /* 511 * Evil hack: Only MIPS should be non-relocatable, and the 512 * psections should have a high address (typically 0x5ffe0000). 513 * If it's now relocatable, it should be linked at 0 and the 514 * psections should have zeros in the upper part of the address. 515 * Otherwise, force the load at the linked address. 516 */ 517 if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0) 518 *last = ELFDEFNNAME(NO_ADDR); 519 #endif 520 521 /* 522 * If no position to load the interpreter was set by a probe 523 * function, pick the same address that a non-fixed mmap(0, ..) 524 * would (i.e. something safely out of the way). 525 */ 526 if (*last == ELFDEFNNAME(NO_ADDR)) { 527 u_long limit = 0; 528 /* 529 * Find the start and ending addresses of the psections to 530 * be loaded. This will give us the size. 531 */ 532 for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) { 533 if (ph[i].p_type == PT_LOAD) { 534 u_long psize = ph[i].p_vaddr + ph[i].p_memsz; 535 if (base_ph == NULL) 536 base_ph = &ph[i]; 537 if (psize > limit) 538 limit = psize; 539 } 540 } 541 542 if (base_ph == NULL) { 543 DPRINTF("no interpreter loadable sections"); 544 error = ENOEXEC; 545 goto bad; 546 } 547 548 /* 549 * Now compute the size and load address. 550 */ 551 addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p, 552 epp->ep_daddr, 553 round_page(limit) - trunc_page(base_ph->p_vaddr), 554 use_topdown); 555 addr += (Elf_Addr)pax_aslr_rtld_offset(epp, base_ph->p_align, 556 use_topdown); 557 } else { 558 addr = *last; /* may be ELF_LINK_ADDR */ 559 } 560 561 /* 562 * Load all the necessary sections 563 */ 564 for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) { 565 switch (ph[i].p_type) { 566 case PT_LOAD: { 567 u_long size; 568 int flags; 569 570 if (base_ph == NULL) { 571 /* 572 * First encountered psection is always the 573 * base psection. Make sure it's aligned 574 * properly (align down for topdown and align 575 * upwards for not topdown). 576 */ 577 base_ph = &ph[i]; 578 flags = VMCMD_BASE; 579 if (addr == ELF_LINK_ADDR) 580 addr = ph[i].p_vaddr; 581 if (use_topdown) 582 addr = ELF_TRUNC(addr, ph[i].p_align); 583 else 584 addr = ELF_ROUND(addr, ph[i].p_align); 585 } else { 586 u_long limit = round_page(last_ph->p_vaddr 587 + last_ph->p_memsz); 588 u_long base = trunc_page(ph[i].p_vaddr); 589 590 /* 591 * If there is a gap in between the psections, 592 * map it as inaccessible so nothing else 593 * mmap'ed will be placed there. 594 */ 595 if (limit != base) { 596 NEW_VMCMD2(vcset, vmcmd_map_zero, 597 base - limit, 598 limit - base_ph->p_vaddr, NULLVP, 599 0, VM_PROT_NONE, VMCMD_RELATIVE); 600 } 601 602 addr = ph[i].p_vaddr - base_ph->p_vaddr; 603 flags = VMCMD_RELATIVE; 604 } 605 last_ph = &ph[i]; 606 if ((error = elf_load_psection(vcset, vp, &ph[i], &addr, 607 &size, flags)) != 0) 608 goto bad; 609 /* 610 * If entry is within this psection then this 611 * must contain the .text section. *entryoff is 612 * relative to the base psection. 613 */ 614 if (eh.e_entry >= ph[i].p_vaddr && 615 eh.e_entry < (ph[i].p_vaddr + size)) { 616 *entryoff = eh.e_entry - base_ph->p_vaddr; 617 } 618 addr += size; 619 break; 620 } 621 622 default: 623 break; 624 } 625 } 626 627 kmem_free(ph, phsize); 628 /* 629 * This value is ignored if TOPDOWN. 630 */ 631 *last = addr; 632 vrele(vp); 633 return 0; 634 635 badunlock: 636 VOP_UNLOCK(vp); 637 638 bad: 639 if (ph != NULL) 640 kmem_free(ph, phsize); 641 vrele(vp); 642 return error; 643 } 644 645 /* 646 * exec_elf_makecmds(): Prepare an Elf binary's exec package 647 * 648 * First, set of the various offsets/lengths in the exec package. 649 * 650 * Then, mark the text image busy (so it can be demand paged) or error 651 * out if this is not possible. Finally, set up vmcmds for the 652 * text, data, bss, and stack segments. 653 */ 654 int 655 exec_elf_makecmds(struct lwp *l, struct exec_package *epp) 656 { 657 Elf_Ehdr *eh = epp->ep_hdr; 658 Elf_Phdr *ph, *pp; 659 Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0; 660 int error, i; 661 char *interp = NULL; 662 u_long phsize; 663 struct elf_args *ap; 664 bool is_dyn = false; 665 666 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) { 667 DPRINTF("small header %#x", epp->ep_hdrvalid); 668 return ENOEXEC; 669 } 670 if ((error = elf_check_header(eh)) != 0) 671 return error; 672 673 if (eh->e_type == ET_DYN) 674 /* PIE, and some libs have an entry point */ 675 is_dyn = true; 676 else if (eh->e_type != ET_EXEC) { 677 DPRINTF("bad type %#x", eh->e_type); 678 return ENOEXEC; 679 } 680 681 if (eh->e_phnum == 0) { 682 DPRINTF("no program headers"); 683 return ENOEXEC; 684 } 685 686 error = vn_marktext(epp->ep_vp); 687 if (error) 688 return error; 689 690 /* 691 * Allocate space to hold all the program headers, and read them 692 * from the file 693 */ 694 phsize = eh->e_phnum * sizeof(Elf_Phdr); 695 ph = kmem_alloc(phsize, KM_SLEEP); 696 697 if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) != 698 0) 699 goto bad; 700 701 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 702 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 703 704 for (i = 0; i < eh->e_phnum; i++) { 705 pp = &ph[i]; 706 if (pp->p_type == PT_INTERP) { 707 if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) { 708 DPRINTF("bad interpreter namelen %#jx", 709 (uintmax_t)pp->p_filesz); 710 error = ENOEXEC; 711 goto bad; 712 } 713 interp = PNBUF_GET(); 714 if ((error = exec_read_from(l, epp->ep_vp, 715 pp->p_offset, interp, pp->p_filesz)) != 0) 716 goto bad; 717 /* Ensure interp is NUL-terminated and of the expected length */ 718 if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) { 719 DPRINTF("bad interpreter name"); 720 error = ENOEXEC; 721 goto bad; 722 } 723 break; 724 } 725 } 726 727 /* 728 * On the same architecture, we may be emulating different systems. 729 * See which one will accept this executable. 730 * 731 * Probe functions would normally see if the interpreter (if any) 732 * exists. Emulation packages may possibly replace the interpreter in 733 * interp with a changed path (/emul/xxx/<path>). 734 */ 735 pos = ELFDEFNNAME(NO_ADDR); 736 if (epp->ep_esch->u.elf_probe_func) { 737 vaddr_t startp = (vaddr_t)pos; 738 739 error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp, 740 &startp); 741 if (error) 742 goto bad; 743 pos = (Elf_Addr)startp; 744 } 745 746 if (is_dyn && (error = elf_placedynexec(epp, eh, ph)) != 0) 747 goto bad; 748 749 /* 750 * Load all the necessary sections 751 */ 752 for (i = 0; i < eh->e_phnum; i++) { 753 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 754 u_long size = 0; 755 756 switch (ph[i].p_type) { 757 case PT_LOAD: 758 if ((error = elf_load_psection(&epp->ep_vmcmds, 759 epp->ep_vp, &ph[i], &addr, &size, VMCMD_FIXED)) 760 != 0) 761 goto bad; 762 763 /* 764 * Consider this as text segment, if it is executable. 765 * If there is more than one text segment, pick the 766 * largest. 767 */ 768 if (ph[i].p_flags & PF_X) { 769 if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) || 770 size > epp->ep_tsize) { 771 epp->ep_taddr = addr; 772 epp->ep_tsize = size; 773 } 774 end_text = addr + size; 775 } else { 776 epp->ep_daddr = addr; 777 epp->ep_dsize = size; 778 } 779 if (ph[i].p_offset == 0) { 780 computed_phdr = ph[i].p_vaddr + eh->e_phoff; 781 } 782 break; 783 784 case PT_SHLIB: 785 /* SCO has these sections. */ 786 case PT_INTERP: 787 /* Already did this one. */ 788 case PT_DYNAMIC: 789 case PT_NOTE: 790 break; 791 case PT_PHDR: 792 /* Note address of program headers (in text segment) */ 793 phdr = ph[i].p_vaddr; 794 break; 795 796 default: 797 /* 798 * Not fatal; we don't need to understand everything. 799 */ 800 break; 801 } 802 } 803 804 if (epp->ep_vmcmds.evs_used == 0) { 805 /* No VMCMD; there was no PT_LOAD section, or those 806 * sections were empty */ 807 DPRINTF("no vmcommands"); 808 error = ENOEXEC; 809 goto bad; 810 } 811 812 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 813 epp->ep_daddr = round_page(end_text); 814 epp->ep_dsize = 0; 815 } 816 817 /* 818 * Check if we found a dynamically linked binary and arrange to load 819 * its interpreter 820 */ 821 if (interp) { 822 u_int nused = epp->ep_vmcmds.evs_used; 823 u_long interp_offset = 0; 824 825 if ((error = elf_load_interp(l, epp, interp, 826 &epp->ep_vmcmds, &interp_offset, &pos)) != 0) { 827 goto bad; 828 } 829 if (epp->ep_vmcmds.evs_used == nused) { 830 /* elf_load_interp() has not set up any new VMCMD */ 831 DPRINTF("no vmcommands for interpreter"); 832 error = ENOEXEC; 833 goto bad; 834 } 835 836 ap = kmem_alloc(sizeof(*ap), KM_SLEEP); 837 ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr; 838 epp->ep_entryoffset = interp_offset; 839 epp->ep_entry = ap->arg_interp + interp_offset; 840 PNBUF_PUT(interp); 841 interp = NULL; 842 } else { 843 epp->ep_entry = eh->e_entry; 844 if (epp->ep_flags & EXEC_FORCEAUX) { 845 ap = kmem_zalloc(sizeof(*ap), KM_SLEEP); 846 ap->arg_interp = (vaddr_t)NULL; 847 } else { 848 ap = NULL; 849 } 850 } 851 852 if (ap) { 853 ap->arg_phaddr = phdr ? phdr : computed_phdr; 854 ap->arg_phentsize = eh->e_phentsize; 855 ap->arg_phnum = eh->e_phnum; 856 ap->arg_entry = eh->e_entry; 857 epp->ep_emul_arg = ap; 858 epp->ep_emul_arg_free = elf_free_emul_arg; 859 } 860 861 #ifdef ELF_MAP_PAGE_ZERO 862 /* Dell SVR4 maps page zero, yeuch! */ 863 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0, 864 epp->ep_vp, 0, VM_PROT_READ); 865 #endif 866 867 error = (*epp->ep_esch->es_setup_stack)(l, epp); 868 if (error) 869 goto bad; 870 871 kmem_free(ph, phsize); 872 return 0; 873 874 bad: 875 if (interp) 876 PNBUF_PUT(interp); 877 exec_free_emul_arg(epp); 878 kmem_free(ph, phsize); 879 kill_vmcmds(&epp->ep_vmcmds); 880 return error; 881 } 882 883 int 884 netbsd_elf_signature(struct lwp *l, struct exec_package *epp, 885 Elf_Ehdr *eh) 886 { 887 size_t i; 888 Elf_Phdr *ph; 889 size_t phsize; 890 char *nbuf; 891 int error; 892 int isnetbsd = 0; 893 894 epp->ep_pax_flags = 0; 895 896 if (eh->e_phnum > ELF_MAXPHNUM || eh->e_phnum == 0) { 897 DPRINTF("no signature %#x", eh->e_phnum); 898 return ENOEXEC; 899 } 900 901 phsize = eh->e_phnum * sizeof(Elf_Phdr); 902 ph = kmem_alloc(phsize, KM_SLEEP); 903 error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize); 904 if (error) 905 goto out; 906 907 nbuf = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP); 908 for (i = 0; i < eh->e_phnum; i++) { 909 const char *nptr; 910 size_t nlen; 911 912 if (ph[i].p_type != PT_NOTE || 913 ph[i].p_filesz > ELF_MAXNOTESIZE) 914 continue; 915 916 nlen = ph[i].p_filesz; 917 error = exec_read_from(l, epp->ep_vp, ph[i].p_offset, 918 nbuf, nlen); 919 if (error) 920 continue; 921 922 nptr = nbuf; 923 while (nlen > 0) { 924 const Elf_Nhdr *np; 925 const char *ndata, *ndesc; 926 927 /* note header */ 928 np = (const Elf_Nhdr *)nptr; 929 if (nlen < sizeof(*np)) { 930 break; 931 } 932 nptr += sizeof(*np); 933 nlen -= sizeof(*np); 934 935 /* note name */ 936 ndata = nptr; 937 if (nlen < roundup(np->n_namesz, 4)) { 938 break; 939 } 940 nptr += roundup(np->n_namesz, 4); 941 nlen -= roundup(np->n_namesz, 4); 942 943 /* note description */ 944 ndesc = nptr; 945 if (nlen < roundup(np->n_descsz, 4)) { 946 break; 947 } 948 nptr += roundup(np->n_descsz, 4); 949 nlen -= roundup(np->n_descsz, 4); 950 951 isnetbsd |= netbsd_elf_note(epp, np, ndata, ndesc); 952 } 953 } 954 kmem_free(nbuf, ELF_MAXNOTESIZE); 955 956 error = isnetbsd ? 0 : ENOEXEC; 957 #ifdef DEBUG_ELF 958 if (error) 959 DPRINTF("not netbsd"); 960 #endif 961 out: 962 kmem_free(ph, phsize); 963 return error; 964 } 965 966 int 967 netbsd_elf_note(struct exec_package *epp, 968 const Elf_Nhdr *np, const char *ndata, const char *ndesc) 969 { 970 int isnetbsd = 0; 971 972 #ifdef DIAGNOSTIC 973 const char *badnote; 974 #define BADNOTE(n) badnote = (n) 975 #else 976 #define BADNOTE(n) 977 #endif 978 979 switch (np->n_type) { 980 case ELF_NOTE_TYPE_NETBSD_TAG: 981 /* It is us */ 982 if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ && 983 np->n_descsz == ELF_NOTE_NETBSD_DESCSZ && 984 memcmp(ndata, ELF_NOTE_NETBSD_NAME, 985 ELF_NOTE_NETBSD_NAMESZ) == 0) { 986 memcpy(&epp->ep_osversion, ndesc, 987 ELF_NOTE_NETBSD_DESCSZ); 988 isnetbsd = 1; 989 break; 990 } 991 992 /* 993 * Ignore SuSE tags; SuSE's n_type is the same the 994 * NetBSD one. 995 */ 996 if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ && 997 memcmp(ndata, ELF_NOTE_SUSE_NAME, 998 ELF_NOTE_SUSE_NAMESZ) == 0) 999 break; 1000 /* 1001 * Ignore old GCC 1002 */ 1003 if (np->n_namesz == ELF_NOTE_OGCC_NAMESZ && 1004 memcmp(ndata, ELF_NOTE_OGCC_NAME, 1005 ELF_NOTE_OGCC_NAMESZ) == 0) 1006 break; 1007 BADNOTE("NetBSD tag"); 1008 goto bad; 1009 1010 case ELF_NOTE_TYPE_PAX_TAG: 1011 if (np->n_namesz == ELF_NOTE_PAX_NAMESZ && 1012 np->n_descsz == ELF_NOTE_PAX_DESCSZ && 1013 memcmp(ndata, ELF_NOTE_PAX_NAME, 1014 ELF_NOTE_PAX_NAMESZ) == 0) { 1015 uint32_t flags; 1016 memcpy(&flags, ndesc, sizeof(flags)); 1017 /* Convert the flags and insert them into 1018 * the exec package. */ 1019 pax_setup_elf_flags(epp, flags); 1020 break; 1021 } 1022 BADNOTE("PaX tag"); 1023 goto bad; 1024 1025 case ELF_NOTE_TYPE_MARCH_TAG: 1026 /* Copy the machine arch into the package. */ 1027 if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ 1028 && memcmp(ndata, ELF_NOTE_MARCH_NAME, 1029 ELF_NOTE_MARCH_NAMESZ) == 0) { 1030 /* Do not truncate the buffer */ 1031 if (np->n_descsz > sizeof(epp->ep_machine_arch)) { 1032 BADNOTE("description size limit"); 1033 goto bad; 1034 } 1035 /* 1036 * Ensure ndesc is NUL-terminated and of the 1037 * expected length. 1038 */ 1039 if (strnlen(ndesc, np->n_descsz) + 1 != 1040 np->n_descsz) { 1041 BADNOTE("description size"); 1042 goto bad; 1043 } 1044 strlcpy(epp->ep_machine_arch, ndesc, 1045 sizeof(epp->ep_machine_arch)); 1046 break; 1047 } 1048 BADNOTE("march tag"); 1049 goto bad; 1050 1051 case ELF_NOTE_TYPE_MCMODEL_TAG: 1052 /* arch specific check for code model */ 1053 #ifdef ELF_MD_MCMODEL_CHECK 1054 if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ 1055 && memcmp(ndata, ELF_NOTE_MCMODEL_NAME, 1056 ELF_NOTE_MCMODEL_NAMESZ) == 0) { 1057 ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz); 1058 break; 1059 } 1060 BADNOTE("mcmodel tag"); 1061 goto bad; 1062 #endif 1063 break; 1064 1065 case ELF_NOTE_TYPE_SUSE_VERSION_TAG: 1066 break; 1067 1068 case ELF_NOTE_TYPE_GO_BUILDID_TAG: 1069 break; 1070 1071 case ELF_NOTE_TYPE_NETBSD_EMUL_TAG: 1072 /* Ancient NetBSD version tag */ 1073 break; 1074 1075 default: 1076 BADNOTE("unknown tag"); 1077 bad: 1078 #ifdef DIAGNOSTIC 1079 /* Ignore GNU tags */ 1080 if (np->n_namesz == ELF_NOTE_GNU_NAMESZ && 1081 memcmp(ndata, ELF_NOTE_GNU_NAME, 1082 ELF_NOTE_GNU_NAMESZ) == 0) 1083 break; 1084 1085 int ns = (int)np->n_namesz; 1086 printf("%s: Unknown elf note type %d (%s): " 1087 "[namesz=%d, descsz=%d name=%-*.*s]\n", 1088 epp->ep_kname, np->n_type, badnote, np->n_namesz, 1089 np->n_descsz, ns, ns, ndata); 1090 #endif 1091 break; 1092 } 1093 1094 return isnetbsd; 1095 } 1096 1097 int 1098 netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp, 1099 vaddr_t *pos) 1100 { 1101 int error; 1102 1103 if ((error = netbsd_elf_signature(l, epp, eh)) != 0) 1104 return error; 1105 #ifdef ELF_MD_PROBE_FUNC 1106 if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0) 1107 return error; 1108 #elif defined(ELF_INTERP_NON_RELOCATABLE) 1109 *pos = ELF_LINK_ADDR; 1110 #endif 1111 epp->ep_flags |= EXEC_FORCEAUX; 1112 return 0; 1113 } 1114 1115 void 1116 elf_free_emul_arg(void *arg) 1117 { 1118 struct elf_args *ap = arg; 1119 KASSERT(ap != NULL); 1120 kmem_free(ap, sizeof(*ap)); 1121 } 1122