1 /* $NetBSD: exec_elf32.c,v 1.23 1997/03/13 02:55:25 hpeyerl 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 #define CONCAT(x,y) __CONCAT(x,y) 68 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 69 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 70 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 71 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 72 73 int ELFNAME(check_header) __P((Elf_Ehdr *, int)); 74 int ELFNAME(load_file) __P((struct proc *, struct exec_package *, char *, 75 struct exec_vmcmd_set *, u_long *, struct elf_args *, Elf_Addr *)); 76 void ELFNAME(load_psection) __P((struct exec_vmcmd_set *, struct vnode *, 77 Elf_Phdr *, Elf_Addr *, u_long *, int *)); 78 79 extern char sigcode[], esigcode[]; 80 #ifdef SYSCALL_DEBUG 81 extern char *syscallnames[]; 82 #endif 83 84 struct emul ELFNAMEEND(emul_netbsd) = { 85 "netbsd", 86 NULL, 87 sendsig, 88 SYS_syscall, 89 SYS_MAXSYSCALL, 90 sysent, 91 #ifdef SYSCALL_DEBUG 92 syscallnames, 93 #else 94 NULL, 95 #endif 96 ELF_AUX_ENTRIES * sizeof(AuxInfo), 97 ELFNAME(copyargs), 98 setregs, 99 sigcode, 100 esigcode, 101 }; 102 103 int (*ELFNAME(probe_funcs)[]) __P((struct proc *, struct exec_package *, 104 Elf_Ehdr *, char *, Elf_Addr *)) = { 105 #if defined(COMPAT_LINUX) && (ELFSIZE == 32) 106 ELFNAME2(linux,probe), /* XXX not 64-bit safe */ 107 #endif 108 #if defined(COMPAT_SVR4) && (ELFSIZE == 32) 109 ELFNAME2(svr4,probe), /* XXX not 64-bit safe */ 110 #endif 111 }; 112 113 /* round up and down to page boundaries. */ 114 #define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1)) 115 #define ELF_TRUNC(a, b) ((a) & ~((b) - 1)) 116 117 /* 118 * Copy arguments onto the stack in the normal way, but add some 119 * extra information in case of dynamic binding. 120 */ 121 void * 122 ELFNAME(copyargs)(pack, arginfo, stack, argp) 123 struct exec_package *pack; 124 struct ps_strings *arginfo; 125 void *stack; 126 void *argp; 127 { 128 size_t len; 129 AuxInfo ai[ELF_AUX_ENTRIES], *a; 130 struct elf_args *ap; 131 132 stack = copyargs(pack, arginfo, stack, argp); 133 if (!stack) 134 return NULL; 135 136 a = ai; 137 138 /* 139 * Push extra arguments on the stack needed by dynamically 140 * linked binaries 141 */ 142 if ((ap = (struct elf_args *)pack->ep_emul_arg)) { 143 144 a->au_id = AUX_phdr; 145 a->au_v = ap->arg_phaddr; 146 a++; 147 148 a->au_id = AUX_phent; 149 a->au_v = ap->arg_phentsize; 150 a++; 151 152 a->au_id = AUX_phnum; 153 a->au_v = ap->arg_phnum; 154 a++; 155 156 a->au_id = AUX_pagesz; 157 a->au_v = NBPG; 158 a++; 159 160 a->au_id = AUX_base; 161 a->au_v = ap->arg_interp; 162 a++; 163 164 a->au_id = AUX_flags; 165 a->au_v = 0; 166 a++; 167 168 a->au_id = AUX_entry; 169 a->au_v = ap->arg_entry; 170 a++; 171 172 free((char *)ap, M_TEMP); 173 pack->ep_emul_arg = NULL; 174 } 175 176 a->au_id = AUX_null; 177 a->au_v = 0; 178 a++; 179 180 len = (a - ai) * sizeof (AuxInfo); 181 if (copyout(ai, stack, len)) 182 return NULL; 183 stack += len; 184 185 return stack; 186 } 187 188 /* 189 * elf_check_header(): 190 * 191 * Check header for validity; return 0 of ok ENOEXEC if error 192 */ 193 int 194 ELFNAME(check_header)(eh, type) 195 Elf_Ehdr *eh; 196 int type; 197 { 198 199 if (bcmp(eh->e_ident, Elf_e_ident, Elf_e_siz) != 0) 200 return ENOEXEC; 201 202 switch (eh->e_machine) { 203 204 ELFDEFNNAME(MACHDEP_ID_CASES) 205 206 default: 207 return ENOEXEC; 208 } 209 210 if (eh->e_type != type) 211 return ENOEXEC; 212 213 return 0; 214 } 215 216 /* 217 * elf_load_psection(): 218 * 219 * Load a psection at the appropriate address 220 */ 221 void 222 ELFNAME(load_psection)(vcset, vp, ph, addr, size, prot) 223 struct exec_vmcmd_set *vcset; 224 struct vnode *vp; 225 Elf_Phdr *ph; 226 Elf_Addr *addr; 227 u_long *size; 228 int *prot; 229 { 230 u_long uaddr, msize, psize, rm, rf; 231 long diff, offset; 232 233 /* 234 * If the user specified an address, then we load there. 235 */ 236 if (*addr != ELFDEFNNAME(NO_ADDR)) { 237 if (ph->p_align > 1) { 238 *addr = ELF_ROUND(*addr, ph->p_align); 239 uaddr = ELF_TRUNC(ph->p_vaddr, ph->p_align); 240 } else 241 uaddr = ph->p_vaddr; 242 diff = ph->p_vaddr - uaddr; 243 } else { 244 *addr = uaddr = ph->p_vaddr; 245 if (ph->p_align > 1) 246 *addr = ELF_TRUNC(uaddr, ph->p_align); 247 diff = uaddr - *addr; 248 } 249 250 *prot |= (ph->p_flags & Elf_pf_r) ? VM_PROT_READ : 0; 251 *prot |= (ph->p_flags & Elf_pf_w) ? VM_PROT_WRITE : 0; 252 *prot |= (ph->p_flags & Elf_pf_x) ? VM_PROT_EXECUTE : 0; 253 254 offset = ph->p_offset - diff; 255 *size = ph->p_filesz + diff; 256 msize = ph->p_memsz + diff; 257 psize = round_page(*size); 258 259 if ((ph->p_flags & Elf_pf_w) != 0) { 260 /* 261 * Because the pagedvn pager can't handle zero fill of the last 262 * data page if it's not page aligned we map the last page 263 * readvn. 264 */ 265 psize = trunc_page(*size); 266 NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, 267 offset, *prot); 268 if(psize != *size) 269 NEW_VMCMD(vcset, vmcmd_map_readvn, *size - psize, 270 *addr + psize, vp, offset + psize, *prot); 271 } else 272 NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp, 273 offset, *prot); 274 275 /* 276 * Check if we need to extend the size of the segment 277 */ 278 rm = round_page(*addr + msize); 279 rf = round_page(*addr + *size); 280 281 if (rm != rf) { 282 NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 283 0, *prot); 284 *size = msize; 285 } 286 } 287 288 /* 289 * elf_read_from(): 290 * 291 * Read from vnode into buffer at offset. 292 */ 293 int 294 ELFNAME(read_from)(p, vp, off, buf, size) 295 struct vnode *vp; 296 u_long off; 297 struct proc *p; 298 caddr_t buf; 299 int size; 300 { 301 int error; 302 int resid; 303 304 if ((error = vn_rdwr(UIO_READ, vp, buf, size, off, UIO_SYSSPACE, 305 0, p->p_ucred, &resid, p)) != 0) 306 return error; 307 /* 308 * See if we got all of it 309 */ 310 if (resid != 0) 311 return ENOEXEC; 312 return 0; 313 } 314 315 /* 316 * elf_load_file(): 317 * 318 * Load a file (interpreter/library) pointed to by path 319 * [stolen from coff_load_shlib()]. Made slightly generic 320 * so it might be used externally. 321 */ 322 int 323 ELFNAME(load_file)(p, epp, path, vcset, entry, ap, last) 324 struct proc *p; 325 struct exec_package *epp; 326 char *path; 327 struct exec_vmcmd_set *vcset; 328 u_long *entry; 329 struct elf_args *ap; 330 Elf_Addr *last; 331 { 332 int error, i; 333 struct nameidata nd; 334 struct vnode *vp; 335 struct vattr attr; 336 Elf_Ehdr eh; 337 Elf_Phdr *ph = NULL; 338 u_long phsize; 339 char *bp = NULL; 340 Elf_Addr addr = *last; 341 342 bp = path; 343 /* 344 * 1. open file 345 * 2. read filehdr 346 * 3. map text, data, and bss out of it using VM_* 347 */ 348 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, path, p); 349 if ((error = namei(&nd)) != 0) 350 return error; 351 vp = nd.ni_vp; 352 353 /* check for regular file */ 354 if (vp->v_type != VREG) { 355 error = EACCES; 356 goto badunlock; 357 } 358 359 /* get attributes */ 360 if ((error = VOP_GETATTR(vp, &attr, p->p_ucred, p)) != 0) 361 goto badunlock; 362 363 /* 364 * Check mount point. Though we're not trying to exec this binary, 365 * we will be executing code from it, so if the mount point 366 * disallows execution or set-id-ness, we punt or kill the set-id. 367 */ 368 if (vp->v_mount->mnt_flag & MNT_NOEXEC) { 369 error = EACCES; 370 goto badunlock; 371 } 372 if (vp->v_mount->mnt_flag & MNT_NOSUID) 373 epp->ep_vap->va_mode &= ~(VSUID | VSGID); 374 375 /* 376 * Similarly, if it's not marked as executable, we don't allow 377 * it to be used. For root we have to see if any exec bit on. 378 */ 379 if ((error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p)) != 0) 380 goto badunlock; 381 if ((attr.va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0) { 382 error = EACCES; 383 goto badunlock; 384 } 385 386 #ifdef notyet /* XXX cgd 960926 */ 387 XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?) 388 #endif 389 VOP_UNLOCK(vp); 390 391 if ((error = ELFNAME(read_from)(p, vp, 0, (caddr_t) &eh, 392 sizeof(eh))) != 0) 393 goto bad; 394 395 if ((error = ELFNAME(check_header)(&eh, Elf_et_dyn)) != 0) 396 goto bad; 397 398 phsize = eh.e_phnum * sizeof(Elf_Phdr); 399 ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK); 400 401 if ((error = ELFNAME(read_from)(p, vp, eh.e_phoff, 402 (caddr_t) ph, phsize)) != 0) 403 goto bad; 404 405 /* 406 * Load all the necessary sections 407 */ 408 for (i = 0; i < eh.e_phnum; i++) { 409 u_long size = 0; 410 int prot = 0; 411 412 switch (ph[i].p_type) { 413 case Elf_pt_load: 414 ELFNAME(load_psection)(vcset, vp, &ph[i], &addr, 415 &size, &prot); 416 /* If entry is within this section it must be text */ 417 if (eh.e_entry >= ph[i].p_vaddr && 418 eh.e_entry < (ph[i].p_vaddr + size)) { 419 /* XXX */ 420 *entry = addr + eh.e_entry; 421 #ifdef mips 422 *entry -= ph[i].p_vaddr; 423 #endif 424 ap->arg_interp = addr; 425 } 426 addr += size; 427 break; 428 429 case Elf_pt_dynamic: 430 case Elf_pt_phdr: 431 case Elf_pt_note: 432 break; 433 434 default: 435 break; 436 } 437 } 438 439 free((char *)ph, M_TEMP); 440 *last = addr; 441 vrele(vp); 442 return 0; 443 444 badunlock: 445 VOP_UNLOCK(vp); 446 447 bad: 448 if (ph != NULL) 449 free((char *)ph, M_TEMP); 450 #ifdef notyet /* XXX cgd 960926 */ 451 (maybe) VOP_CLOSE it 452 #endif 453 vrele(vp); 454 return error; 455 } 456 457 /* 458 * exec_elf_makecmds(): Prepare an Elf binary's exec package 459 * 460 * First, set of the various offsets/lengths in the exec package. 461 * 462 * Then, mark the text image busy (so it can be demand paged) or error 463 * out if this is not possible. Finally, set up vmcmds for the 464 * text, data, bss, and stack segments. 465 */ 466 int 467 ELFNAME2(exec,makecmds)(p, epp) 468 struct proc *p; 469 struct exec_package *epp; 470 { 471 Elf_Ehdr *eh = epp->ep_hdr; 472 Elf_Phdr *ph, *pp; 473 Elf_Addr phdr = 0, pos = 0; 474 int error, i, n, nload; 475 char interp[MAXPATHLEN]; 476 u_long phsize; 477 478 if (epp->ep_hdrvalid < sizeof(Elf_Ehdr)) 479 return ENOEXEC; 480 481 if (ELFNAME(check_header)(eh, Elf_et_exec)) 482 return ENOEXEC; 483 484 /* 485 * check if vnode is in open for writing, because we want to 486 * demand-page out of it. if it is, don't do it, for various 487 * reasons 488 */ 489 if (epp->ep_vp->v_writecount != 0) { 490 #ifdef DIAGNOSTIC 491 if (epp->ep_vp->v_flag & VTEXT) 492 panic("exec: a VTEXT vnode has writecount != 0\n"); 493 #endif 494 return ETXTBSY; 495 } 496 /* 497 * Allocate space to hold all the program headers, and read them 498 * from the file 499 */ 500 phsize = eh->e_phnum * sizeof(Elf_Phdr); 501 ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK); 502 503 if ((error = ELFNAME(read_from)(p, epp->ep_vp, eh->e_phoff, 504 (caddr_t) ph, phsize)) != 0) 505 goto bad; 506 507 epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR); 508 epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR); 509 510 interp[0] = '\0'; 511 512 for (i = 0; i < eh->e_phnum; i++) { 513 pp = &ph[i]; 514 if (pp->p_type == Elf_pt_interp) { 515 if (pp->p_filesz >= sizeof(interp)) 516 goto bad; 517 if ((error = ELFNAME(read_from)(p, epp->ep_vp, 518 pp->p_offset, (caddr_t) interp, 519 pp->p_filesz)) != 0) 520 goto bad; 521 break; 522 } 523 } 524 525 /* 526 * Setup things for native emulation. 527 */ 528 epp->ep_emul = &ELFNAMEEND(emul_netbsd); 529 pos = ELFDEFNNAME(NO_ADDR); 530 531 /* 532 * On the same architecture, we may be emulating different systems. 533 * See which one will accept this executable. This currently only 534 * applies to Linux and SVR4 on the i386. 535 * 536 * Probe functions would normally see if the interpreter (if any) 537 * exists. Emulation packages may possibly replace the interpreter in 538 * interp[] with a changed path (/emul/xxx/<path>), and also 539 * set the ep_emul field in the exec package structure. 540 */ 541 n = sizeof ELFNAME(probe_funcs) / sizeof ELFNAME(probe_funcs)[0]; 542 if (n != 0) { 543 error = ENOEXEC; 544 for (i = 0; i < n && error; i++) 545 error = ELFNAME(probe_funcs)[i](p, epp, eh, 546 interp, &pos); 547 548 #ifdef notyet 549 /* 550 * We should really use a signature in our native binaries 551 * and have our own probe function for matching binaries, 552 * before trying the emulations. For now, if the emulation 553 * probes failed we default to native. 554 */ 555 if (error) 556 goto bad; 557 #endif 558 } 559 560 /* 561 * Load all the necessary sections 562 */ 563 for (i = nload = 0; i < eh->e_phnum; i++) { 564 Elf_Addr addr = ELFDEFNNAME(NO_ADDR); 565 u_long size = 0; 566 int prot = 0; 567 568 pp = &ph[i]; 569 570 switch (ph[i].p_type) { 571 case Elf_pt_load: 572 /* 573 * XXX 574 * Can handle only 2 sections: text and data 575 */ 576 if (nload++ == 2) 577 goto bad; 578 ELFNAME(load_psection)(&epp->ep_vmcmds, epp->ep_vp, 579 &ph[i], &addr, &size, &prot); 580 581 /* 582 * Decide whether it's text or data by looking 583 * at the entry point. 584 */ 585 if (eh->e_entry >= addr && 586 eh->e_entry < (addr + size)) { 587 epp->ep_taddr = addr; 588 epp->ep_tsize = size; 589 if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) { 590 epp->ep_daddr = addr; 591 epp->ep_dsize = size; 592 } 593 } else { 594 epp->ep_daddr = addr; 595 epp->ep_dsize = size; 596 } 597 break; 598 599 case Elf_pt_shlib: 600 error = ENOEXEC; 601 goto bad; 602 603 case Elf_pt_interp: 604 /* Already did this one */ 605 case Elf_pt_dynamic: 606 case Elf_pt_note: 607 break; 608 609 case Elf_pt_phdr: 610 /* Note address of program headers (in text segment) */ 611 phdr = pp->p_vaddr; 612 break; 613 614 default: 615 /* 616 * Not fatal; we don't need to understand everything. 617 */ 618 break; 619 } 620 } 621 622 /* this breaks on, e.g., OpenBSD-compatible mips shared binaries. */ 623 #ifndef ELF_INTERP_NON_RELOCATABLE 624 /* 625 * If no position to load the interpreter was set by a probe 626 * function, pick the same address that a non-fixed mmap(0, ..) 627 * would (i.e. something safely out of the way). 628 */ 629 if (pos == ELFDEFNNAME(NO_ADDR)) 630 pos = round_page(epp->ep_daddr + MAXDSIZ); 631 #endif /* !ELF_INTERP_NON_RELOCATABLE */ 632 633 /* 634 * Check if we found a dynamically linked binary and arrange to load 635 * it's interpreter 636 */ 637 if (interp[0]) { 638 struct elf_args *ap; 639 640 ap = (struct elf_args *)malloc(sizeof(struct elf_args), 641 M_TEMP, M_WAITOK); 642 if ((error = ELFNAME(load_file)(p, epp, interp, 643 &epp->ep_vmcmds, &epp->ep_entry, ap, &pos)) != 0) { 644 free((char *)ap, M_TEMP); 645 goto bad; 646 } 647 pos += phsize; 648 ap->arg_phaddr = phdr; 649 650 ap->arg_phentsize = eh->e_phentsize; 651 ap->arg_phnum = eh->e_phnum; 652 ap->arg_entry = eh->e_entry; 653 654 epp->ep_emul_arg = ap; 655 } else 656 epp->ep_entry = eh->e_entry; 657 658 #ifdef ELF_MAP_PAGE_ZERO 659 /* Dell SVR4 maps page zero, yeuch! */ 660 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0, 661 VM_PROT_READ); 662 #endif 663 free((char *)ph, M_TEMP); 664 epp->ep_vp->v_flag |= VTEXT; 665 return exec_elf_setup_stack(p, epp); 666 667 bad: 668 free((char *)ph, M_TEMP); 669 kill_vmcmds(&epp->ep_vmcmds); 670 return ENOEXEC; 671 } 672