1 /* $NetBSD: exec_elf32.c,v 1.28 1998/03/01 02:22:27 fvdl Exp $ */ 2 3 /* 4 * Copyright (c) 1996 Christopher G. Demetriou 5 * Copyright (c) 1994 Christos Zoulas 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 /* If not included by exec_elf64.c, ELFSIZE won't be defined. */ 32 #ifndef ELFSIZE 33 #define ELFSIZE 32 34 #endif 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/kernel.h> 39 #include <sys/proc.h> 40 #include <sys/malloc.h> 41 #include <sys/namei.h> 42 #include <sys/vnode.h> 43 #include <sys/exec.h> 44 #include <sys/exec_elf.h> 45 #include <sys/fcntl.h> 46 #include <sys/syscall.h> 47 #include <sys/signalvar.h> 48 #include <sys/mount.h> 49 #include <sys/stat.h> 50 51 #include <sys/mman.h> 52 #include <vm/vm.h> 53 #include <vm/vm_param.h> 54 #include <vm/vm_map.h> 55 56 #include <machine/cpu.h> 57 #include <machine/reg.h> 58 59 #ifdef COMPAT_LINUX 60 #include <compat/linux/linux_exec.h> 61 #endif 62 63 #ifdef COMPAT_SVR4 64 #include <compat/svr4/svr4_exec.h> 65 #endif 66 67 #ifdef COMPAT_IBCS2 68 #include <compat/ibcs2/ibcs2_exec.h> 69 #endif 70 71 #define CONCAT(x,y) __CONCAT(x,y) 72 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 73 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 74 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 75 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 76 77 int ELFNAME(check_header) __P((Elf_Ehdr *, int)); 78 int ELFNAME(load_file) __P((struct proc *, struct exec_package *, char *, 79 struct exec_vmcmd_set *, u_long *, struct elf_args *, Elf_Addr *)); 80 void ELFNAME(load_psection) __P((struct exec_vmcmd_set *, struct vnode *, 81 Elf_Phdr *, Elf_Addr *, u_long *, int *)); 82 83 extern char sigcode[], esigcode[]; 84 #ifdef SYSCALL_DEBUG 85 extern char *syscallnames[]; 86 #endif 87 88 struct emul ELFNAMEEND(emul_netbsd) = { 89 "netbsd", 90 NULL, 91 sendsig, 92 SYS_syscall, 93 SYS_MAXSYSCALL, 94 sysent, 95 #ifdef SYSCALL_DEBUG 96 syscallnames, 97 #else 98 NULL, 99 #endif 100 ELF_AUX_ENTRIES * sizeof(AuxInfo), 101 ELFNAME(copyargs), 102 setregs, 103 sigcode, 104 esigcode, 105 }; 106 107 int (*ELFNAME(probe_funcs)[]) __P((struct proc *, struct exec_package *, 108 Elf_Ehdr *, char *, Elf_Addr *)) = { 109 #if defined(COMPAT_LINUX) && (ELFSIZE == 32) 110 ELFNAME2(linux,probe), /* XXX not 64-bit safe */ 111 #endif 112 #if defined(COMPAT_SVR4) && (ELFSIZE == 32) 113 ELFNAME2(svr4,probe), /* XXX not 64-bit safe */ 114 #endif 115 #if defined(COMPAT_IBCS2) && (ELFSIZE == 32) 116 ELFNAME2(ibcs2,probe), /* XXX not 64-bit safe */ 117 #endif 118 }; 119 120 /* round up and down to page boundaries. */ 121 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 122 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1)) 123 124 /* 125 * Copy arguments onto the stack in the normal way, but add some 126 * extra information in case of dynamic binding. 127 */ 128 void * 129 ELFNAME(copyargs)(pack, arginfo, stack, argp) 130 struct exec_package *pack; 131 struct ps_strings *arginfo; 132 void *stack; 133 void *argp; 134 { 135 size_t len; 136 AuxInfo ai[ELF_AUX_ENTRIES], *a; 137 struct elf_args *ap; 138 139 stack = copyargs(pack, arginfo, stack, argp); 140 if (!stack) 141 return NULL; 142 143 a = ai; 144 145 /* 146 * Push extra arguments on the stack needed by dynamically 147 * linked binaries 148 */ 149 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 150 151 a->au_id = AUX_phdr; 152 a->au_v = ap->arg_phaddr; 153 a++; 154 155 a->au_id = AUX_phent; 156 a->au_v = ap->arg_phentsize; 157 a++; 158 159 a->au_id = AUX_phnum; 160 a->au_v = ap->arg_phnum; 161 a++; 162 163 a->au_id = AUX_pagesz; 164 a->au_v = NBPG; 165 a++; 166 167 a->au_id = AUX_base; 168 a->au_v = ap->arg_interp; 169 a++; 170 171 a->au_id = AUX_flags; 172 a->au_v = 0; 173 a++; 174 175 a->au_id = AUX_entry; 176 a->au_v = ap->arg_entry; 177 a++; 178 179 free((char *)ap, M_TEMP); 180 pack->ep_emul_arg = NULL; 181 } 182 183 a->au_id = AUX_null; 184 a->au_v = 0; 185 a++; 186 187 len = (a - ai) * sizeof (AuxInfo); 188 if (copyout(ai, stack, len)) 189 return NULL; 190 stack += len; 191 192 return stack; 193 } 194 195 /* 196 * elf_check_header(): 197 * 198 * Check header for validity; return 0 of ok ENOEXEC if error 199 */ 200 int 201 ELFNAME(check_header)(eh, type) 202 Elf_Ehdr *eh; 203 int type; 204 { 205 206 if (bcmp(eh->e_ident, Elf_e_ident, Elf_e_siz) != 0) 207 return ENOEXEC; 208 209 switch (eh->e_machine) { 210 211 ELFDEFNNAME(MACHDEP_ID_CASES) 212 213 default: 214 return ENOEXEC; 215 } 216 217 if (eh->e_type != type) 218 return ENOEXEC; 219 220 return 0; 221 } 222 223 /* 224 * elf_load_psection(): 225 * 226 * Load a psection at the appropriate address 227 */ 228 void 229 ELFNAME(load_psection)(vcset, vp, ph, addr, size, prot) 230 struct exec_vmcmd_set *vcset; 231 struct vnode *vp; 232 Elf_Phdr *ph; 233 Elf_Addr *addr; 234 u_long *size; 235 int *prot; 236 { 237 u_long uaddr, msize, psize, rm, rf; 238 long diff, offset; 239 240 /* 241 * If the user specified an address, then we load there. 242 */ 243 if (*addr != ELFDEFNNAME(NO_ADDR)) { 244 if (ph->p_align > 1) { 245 *addr = ELF_ROUND(*addr, ph->p_align); 246 uaddr = ELF_TRUNC(ph->p_vaddr, ph->p_align); 247 } else 248 uaddr = ph->p_vaddr; 249 diff = ph->p_vaddr - uaddr; 250 } else { 251 *addr = uaddr = ph->p_vaddr; 252 if (ph->p_align > 1) 253 *addr = ELF_TRUNC(uaddr, ph->p_align); 254 diff = uaddr - *addr; 255 } 256 257 *prot |= (ph->p_flags & Elf_pf_r) ? VM_PROT_READ : 0; 258 *prot |= (ph->p_flags & Elf_pf_w) ? VM_PROT_WRITE : 0; 259 *prot |= (ph->p_flags & Elf_pf_x) ? VM_PROT_EXECUTE : 0; 260 261 offset = ph->p_offset - diff; 262 *size = ph->p_filesz + diff; 263 msize = ph->p_memsz + diff; 264 psize = round_page(*size); 265 266 if ((ph->p_flags & Elf_pf_w) != 0) { 267 /* 268 * Because the pagedvn pager can't handle zero fill of the last 269 * data page if it's not page aligned we map the last page 270 * readvn. 271 */ 272 psize = trunc_page(*size); 273 NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, 274 offset, *prot); 275 if(psize != *size) 276 NEW_VMCMD(vcset, vmcmd_map_readvn, *size - psize, 277 *addr + psize, vp, offset + psize, *prot); 278 } else 279 NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, 280 offset, *prot); 281 282 /* 283 * Check if we need to extend the size of the segment 284 */ 285 rm = round_page(*addr + msize); 286 rf = round_page(*addr + *size); 287 288 if (rm != rf) { 289 NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 290 0, *prot); 291 *size = msize; 292 } 293 } 294 295 /* 296 * elf_read_from(): 297 * 298 * Read from vnode into buffer at offset. 299 */ 300 int 301 ELFNAME(read_from)(p, vp, off, buf, size) 302 struct vnode *vp; 303 u_long off; 304 struct proc *p; 305 caddr_t buf; 306 int size; 307 { 308 int error; 309 int resid; 310 311 if ((error = vn_rdwr(UIO_READ, vp, buf, size, off, UIO_SYSSPACE, 312 0, p->p_ucred, &resid, p)) != 0) 313 return error; 314 /* 315 * See if we got all of it 316 */ 317 if (resid != 0) 318 return ENOEXEC; 319 return 0; 320 } 321 322 /* 323 * elf_load_file(): 324 * 325 * Load a file (interpreter/library) pointed to by path 326 * [stolen from coff_load_shlib()]. Made slightly generic 327 * so it might be used externally. 328 */ 329 int 330 ELFNAME(load_file)(p, epp, path, vcset, entry, ap, last) 331 struct proc *p; 332 struct exec_package *epp; 333 char *path; 334 struct exec_vmcmd_set *vcset; 335 u_long *entry; 336 struct elf_args *ap; 337 Elf_Addr *last; 338 { 339 int error, i; 340 struct nameidata nd; 341 struct vnode *vp; 342 struct vattr attr; 343 Elf_Ehdr eh; 344 Elf_Phdr *ph = NULL; 345 u_long phsize; 346 char *bp = NULL; 347 Elf_Addr addr = *last; 348 349 bp = path; 350 /* 351 * 1. open file 352 * 2. read filehdr 353 * 3. map text, data, and bss out of it using VM_* 354 */ 355 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, path, p); 356 if ((error = namei(&nd)) != 0) 357 return error; 358 vp = nd.ni_vp; 359 360 /* 361 * Similarly, if it's not marked as executable, or it's not a regular 362 * file, we don't allow it to be used. 363 */ 364 if (vp->v_type != VREG) { 365 error = EACCES; 366 goto badunlock; 367 } 368 if ((error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p)) != 0) 369 goto badunlock; 370 371 /* get attributes */ 372 if ((error = VOP_GETATTR(vp, &attr, p->p_ucred, p)) != 0) 373 goto badunlock; 374 375 /* 376 * Check mount point. Though we're not trying to exec this binary, 377 * we will be executing code from it, so if the mount point 378 * disallows execution or set-id-ness, we punt or kill the set-id. 379 */ 380 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 381 error = EACCES; 382 goto badunlock; 383 } 384 if (vp->v_mount->mnt_flag & MNT_NOSUID) 385 epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID); 386 387 #ifdef notyet /* XXX cgd 960926 */ 388 XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?) 389 #endif 390 VOP_UNLOCK(vp, 0); 391 392 if ((error = ELFNAME(read_from)(p, vp, 0, (caddr_t) &eh, 393 sizeof(eh))) != 0) 394 goto bad; 395 396 if ((error = ELFNAME(check_header)(&eh, Elf_et_dyn)) != 0) 397 goto bad; 398 399 phsize = eh.e_phnum * sizeof(Elf_Phdr); 400 ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK); 401 402 if ((error = ELFNAME(read_from)(p, vp, eh.e_phoff, 403 (caddr_t) ph, phsize)) != 0) 404 goto bad; 405 406 /* 407 * Load all the necessary sections 408 */ 409 for (i = 0; i < eh.e_phnum; i++) { 410 u_long size = 0; 411 int prot = 0; 412 413 switch (ph[i].p_type) { 414 case Elf_pt_load: 415 ELFNAME(load_psection)(vcset, vp, &ph[i], &addr, 416 &size, &prot); 417 /* If entry is within this section it must be text */ 418 if (eh.e_entry >= ph[i].p_vaddr && 419 eh.e_entry < (ph[i].p_vaddr + size)) { 420 /* XXX */ 421 *entry = addr + eh.e_entry; 422 #ifdef mips 423 *entry -= ph[i].p_vaddr; 424 #endif 425 ap->arg_interp = addr; 426 } 427 addr += size; 428 break; 429 430 case Elf_pt_dynamic: 431 case Elf_pt_phdr: 432 case Elf_pt_note: 433 break; 434 435 default: 436 break; 437 } 438 } 439 440 free((char *)ph, M_TEMP); 441 *last = addr; 442 vrele(vp); 443 return 0; 444 445 badunlock: 446 VOP_UNLOCK(vp, 0); 447 448 bad: 449 if (ph != NULL) 450 free((char *)ph, M_TEMP); 451 #ifdef notyet /* XXX cgd 960926 */ 452 (maybe) VOP_CLOSE it 453 #endif 454 vrele(vp); 455 return error; 456 } 457 458 /* 459 * exec_elf_makecmds(): Prepare an Elf binary's exec package 460 * 461 * First, set of the various offsets/lengths in the exec package. 462 * 463 * Then, mark the text image busy (so it can be demand paged) or error 464 * out if this is not possible. Finally, set up vmcmds for the 465 * text, data, bss, and stack segments. 466 */ 467 int 468 ELFNAME2(exec,makecmds)(p, epp) 469 struct proc *p; 470 struct exec_package *epp; 471 { 472 Elf_Ehdr *eh = epp->ep_hdr; 473 Elf_Phdr *ph, *pp; 474 Elf_Addr phdr = 0, pos = 0; 475 int error, i, n, nload; 476 char interp[MAXPATHLEN]; 477 u_long phsize; 478 479 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 480 return ENOEXEC; 481 482 if (ELFNAME(check_header)(eh, Elf_et_exec)) 483 return ENOEXEC; 484 485 /* 486 * check if vnode is in open for writing, because we want to 487 * demand-page out of it. if it is, don't do it, for various 488 * reasons 489 */ 490 if (epp->ep_vp->v_writecount != 0) { 491 #ifdef DIAGNOSTIC 492 if (epp->ep_vp->v_flag & VTEXT) 493 panic("exec: a VTEXT vnode has writecount != 0\n"); 494 #endif 495 return ETXTBSY; 496 } 497 /* 498 * Allocate space to hold all the program headers, and read them 499 * from the file 500 */ 501 phsize = eh->e_phnum * sizeof(Elf_Phdr); 502 ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK); 503 504 if ((error = ELFNAME(read_from)(p, epp->ep_vp, eh->e_phoff, 505 (caddr_t) ph, phsize)) != 0) 506 goto bad; 507 508 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 509 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 510 511 interp[0] = '\0'; 512 513 for (i = 0; i < eh->e_phnum; i++) { 514 pp = &ph[i]; 515 if (pp->p_type == Elf_pt_interp) { 516 if (pp->p_filesz >= sizeof(interp)) 517 goto bad; 518 if ((error = ELFNAME(read_from)(p, epp->ep_vp, 519 pp->p_offset, (caddr_t) interp, 520 pp->p_filesz)) != 0) 521 goto bad; 522 break; 523 } 524 } 525 526 /* 527 * Setup things for native emulation. 528 */ 529 epp->ep_emul = &ELFNAMEEND(emul_netbsd); 530 pos = ELFDEFNNAME(NO_ADDR); 531 532 /* 533 * On the same architecture, we may be emulating different systems. 534 * See which one will accept this executable. This currently only 535 * applies to Linux, SVR4, and IBCS2 on the i386. 536 * 537 * Probe functions would normally see if the interpreter (if any) 538 * exists. Emulation packages may possibly replace the interpreter in 539 * interp[] with a changed path (/emul/xxx/<path>), and also 540 * set the ep_emul field in the exec package structure. 541 */ 542 n = sizeof ELFNAME(probe_funcs) / sizeof ELFNAME(probe_funcs)[0]; 543 if (n != 0) { 544 error = ENOEXEC; 545 for (i = 0; i < n && error; i++) 546 error = ELFNAME(probe_funcs)[i](p, epp, eh, 547 interp, &pos); 548 549 #ifdef notyet 550 /* 551 * We should really use a signature in our native binaries 552 * and have our own probe function for matching binaries, 553 * before trying the emulations. For now, if the emulation 554 * probes failed we default to native. 555 */ 556 if (error) 557 goto bad; 558 #endif 559 } 560 561 /* 562 * Load all the necessary sections 563 */ 564 for (i = nload = 0; i < eh->e_phnum; i++) { 565 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 566 u_long size = 0; 567 int prot = 0; 568 569 pp = &ph[i]; 570 571 switch (ph[i].p_type) { 572 case Elf_pt_load: 573 /* 574 * XXX 575 * Can handle only 2 sections: text and data 576 */ 577 if (nload++ == 2) 578 goto bad; 579 ELFNAME(load_psection)(&epp->ep_vmcmds, epp->ep_vp, 580 &ph[i], &addr, &size, &prot); 581 582 /* 583 * Decide whether it's text or data by looking 584 * at the entry point. 585 */ 586 if (eh->e_entry >= addr && 587 eh->e_entry < (addr + size)) { 588 epp->ep_taddr = addr; 589 epp->ep_tsize = size; 590 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 591 epp->ep_daddr = addr; 592 epp->ep_dsize = size; 593 } 594 } else { 595 epp->ep_daddr = addr; 596 epp->ep_dsize = size; 597 } 598 break; 599 600 case Elf_pt_shlib: 601 #ifndef COMPAT_IBCS2 /* SCO has these sections */ 602 error = ENOEXEC; 603 goto bad; 604 #endif 605 606 case Elf_pt_interp: 607 /* Already did this one */ 608 case Elf_pt_dynamic: 609 case Elf_pt_note: 610 break; 611 612 case Elf_pt_phdr: 613 /* Note address of program headers (in text segment) */ 614 phdr = pp->p_vaddr; 615 break; 616 617 default: 618 /* 619 * Not fatal; we don't need to understand everything. 620 */ 621 break; 622 } 623 } 624 625 /* this breaks on, e.g., OpenBSD-compatible mips shared binaries. */ 626 #ifndef ELF_INTERP_NON_RELOCATABLE 627 /* 628 * If no position to load the interpreter was set by a probe 629 * function, pick the same address that a non-fixed mmap(0, ..) 630 * would (i.e. something safely out of the way). 631 */ 632 if (pos == ELFDEFNNAME(NO_ADDR)) 633 pos = round_page(epp->ep_daddr + MAXDSIZ); 634 #endif /* !ELF_INTERP_NON_RELOCATABLE */ 635 636 /* 637 * Check if we found a dynamically linked binary and arrange to load 638 * it's interpreter 639 */ 640 if (interp[0]) { 641 struct elf_args *ap; 642 643 ap = (struct elf_args *)malloc(sizeof(struct elf_args), 644 M_TEMP, M_WAITOK); 645 if ((error = ELFNAME(load_file)(p, epp, interp, 646 &epp->ep_vmcmds, &epp->ep_entry, ap, &pos)) != 0) { 647 free((char *)ap, M_TEMP); 648 goto bad; 649 } 650 pos += phsize; 651 ap->arg_phaddr = phdr; 652 653 ap->arg_phentsize = eh->e_phentsize; 654 ap->arg_phnum = eh->e_phnum; 655 ap->arg_entry = eh->e_entry; 656 657 epp->ep_emul_arg = ap; 658 } else 659 epp->ep_entry = eh->e_entry; 660 661 #ifdef ELF_MAP_PAGE_ZERO 662 /* Dell SVR4 maps page zero, yeuch! */ 663 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0, 664 VM_PROT_READ); 665 #endif 666 free((char *)ph, M_TEMP); 667 epp->ep_vp->v_flag |= VTEXT; 668 return exec_elf_setup_stack(p, epp); 669 670 bad: 671 free((char *)ph, M_TEMP); 672 kill_vmcmds(&epp->ep_vmcmds); 673 return ENOEXEC; 674 } 675