exec_elf32.c revision 1.2
1/* $NetBSD: exec_elf32.c,v 1.2 1995/06/30 02:57:20 christos Exp $ */ 2 3/* 4 * Copyright (c) 1994 Christos Zoulas 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 */ 30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/kernel.h> 34#include <sys/proc.h> 35#include <sys/malloc.h> 36#include <sys/namei.h> 37#include <sys/vnode.h> 38#include <sys/exec.h> 39#include <sys/exec_elf.h> 40 41#include <sys/mman.h> 42#include <vm/vm.h> 43#include <vm/vm_param.h> 44#include <vm/vm_map.h> 45 46#include <machine/cpu.h> 47#include <machine/reg.h> 48#include <machine/exec.h> 49 50#ifdef COMPAT_LINUX 51#include <compat/linux/linux_exec.h> 52#endif 53 54#ifdef COMPAT_SVR4 55#include <compat/svr4/svr4_exec.h> 56#endif 57 58int (*elf_probe_funcs[])() = { 59#ifdef COMPAT_SVR4 60 svr4_elf_probe, 61#endif 62#ifdef COMPAT_LINUX 63 linux_elf_probe 64#endif 65}; 66 67static int elf_set_segment __P((struct exec_package *, u_long, u_long, 68 int)); 69static int elf_read_from __P((struct proc *, struct vnode *, u_long, 70 caddr_t, int)); 71static void elf_load_psection __P((struct exec_vmcmd_set *, 72 struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *)); 73 74#define ELF_ALIGN(a, b) ((a) & ~((b) - 1)) 75 76/* 77 * Copy arguments onto the stack in the normal way, but add some 78 * extra information in case of dynamic binding. 79 */ 80void * 81elf_copyargs(pack, arginfo, stack, argp) 82 struct exec_package *pack; 83 struct ps_strings *arginfo; 84 void *stack; 85 void *argp; 86{ 87 char **cpp = stack; 88 char *dp, *sp; 89 size_t len; 90 void *nullp = NULL; 91 int argc = arginfo->ps_nargvstr; 92 int envc = arginfo->ps_nenvstr; 93 AuxInfo *a; 94 struct elf_args *ap; 95 96 if (copyout(&argc, cpp++, sizeof(argc))) 97 return NULL; 98 99 dp = (char *) (cpp + argc + envc + 2 + pack->ep_emul->e_arglen); 100 sp = argp; 101 102 /* XXX don't copy them out, remap them! */ 103 arginfo->ps_argvstr = cpp; /* remember location of argv for later */ 104 105 for (; --argc >= 0; sp += len, dp += len) 106 if (copyout(&dp, cpp++, sizeof(dp)) || 107 copyoutstr(sp, dp, ARG_MAX, &len)) 108 return NULL; 109 110 if (copyout(&nullp, cpp++, sizeof(nullp))) 111 return NULL; 112 113 arginfo->ps_envstr = cpp; /* remember location of envp for later */ 114 115 for (; --envc >= 0; sp += len, dp += len) 116 if (copyout(&dp, cpp++, sizeof(dp)) || 117 copyoutstr(sp, dp, ARG_MAX, &len)) 118 return NULL; 119 120 if (copyout(&nullp, cpp++, sizeof(nullp))) 121 return NULL; 122 123 /* 124 * Push extra arguments on the stack needed by dynamically 125 * linked binaries 126 */ 127 a = (AuxInfo *) cpp; 128 if ((ap = (struct elf_args *) pack->ep_emul_arg)) { 129 130 a->au_id = AUX_phdr; 131 a->au_v = ap->arg_phaddr; 132 a++; 133 134 a->au_id = AUX_phent; 135 a->au_v = ap->arg_phentsize; 136 a++; 137 138 a->au_id = AUX_phnum; 139 a->au_v = ap->arg_phnum; 140 a++; 141 142 a->au_id = AUX_pagesz; 143 a->au_v = NBPG; 144 a++; 145 146 a->au_id = AUX_base; 147 a->au_v = ap->arg_interp; 148 a++; 149 150 a->au_id = AUX_flags; 151 a->au_v = 0; 152 a++; 153 154 a->au_id = AUX_entry; 155 a->au_v = ap->arg_entry; 156 a++; 157 158 a->au_id = AUX_null; 159 a->au_v = 0; 160 a++; 161 162 free((char *) ap, M_TEMP); 163 } 164 return a; 165} 166 167/* 168 * elf_check_header(): 169 * 170 * Check header for validity; return 0 of ok ENOEXEC if error 171 * 172 * XXX machine type needs to be moved to <machine/param.h> so 173 * just one comparison can be done. Unfortunately, there is both 174 * em_486 and em_386, so this would not work on the i386. 175 */ 176int 177elf_check_header(eh, type) 178 Elf32_Ehdr *eh; 179 int type; 180{ 181#ifdef sparc 182 /* #$%@#$%@#$%! */ 183# define memcmp bcmp 184#endif 185 if (memcmp(eh->e_ident, Elf32_e_ident, Elf32_e_siz) != 0) 186 return ENOEXEC; 187 188 switch (eh->e_machine) { 189 /* XXX */ 190#ifdef i386 191 case Elf32_em_386: 192 case Elf32_em_486: 193#endif 194#ifdef sparc 195 case Elf32_em_sparc: 196#endif 197 break; 198 199 default: 200 return ENOEXEC; 201 } 202 203 if (eh->e_type != type) 204 return ENOEXEC; 205 206 return 0; 207} 208 209/* 210 * elf_load_psection(): 211 * 212 * Load a psection at the appropriate address 213 */ 214static void 215elf_load_psection(vcset, vp, ph, addr, size, prot) 216 struct exec_vmcmd_set *vcset; 217 struct vnode *vp; 218 Elf32_Phdr *ph; 219 u_long *addr; 220 u_long *size; 221 int *prot; 222{ 223 u_long uaddr, msize, rm, rf; 224 long diff, offset; 225 226 /* 227 * If the user specified an address, then we load there. 228 */ 229 if (*addr != ELF32_NO_ADDR) { 230 if (ph->p_align > 1) { 231 *addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align); 232 uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align); 233 } else 234 uaddr = ph->p_vaddr; 235 diff = ph->p_vaddr - uaddr; 236 } else { 237 *addr = uaddr = ph->p_vaddr; 238 if (ph->p_align > 1) 239 *addr = ELF_ALIGN(uaddr, ph->p_align); 240 diff = uaddr - *addr; 241 } 242 243 *prot |= (ph->p_flags & Elf32_pf_r) ? VM_PROT_READ : 0; 244 *prot |= (ph->p_flags & Elf32_pf_w) ? VM_PROT_WRITE : 0; 245 *prot |= (ph->p_flags & Elf32_pf_x) ? VM_PROT_EXECUTE : 0; 246 247 offset = ph->p_offset - diff; 248 *size = ph->p_filesz + diff; 249 msize = ph->p_memsz + diff; 250 251 NEW_VMCMD(vcset, vmcmd_map_readvn, *size, *addr, vp, offset, *prot); 252 253 /* 254 * Check if we need to extend the size of the segment 255 */ 256 rm = round_page(*addr + msize); 257 rf = round_page(*addr + *size); 258 259 if (rm != rf) { 260 NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot); 261 *size = msize; 262 } 263} 264 265/* 266 * elf_set_segment(): 267 * 268 * Decide if the segment is text or data, depending on the protection 269 * and set it appropriately 270 */ 271static int 272elf_set_segment(epp, vaddr, size, prot) 273 struct exec_package *epp; 274 u_long vaddr; 275 u_long size; 276 int prot; 277{ 278 /* 279 * Kludge: Unfortunately the current implementation of 280 * exec package assumes a single text and data segment. 281 * In Elf we can have more, but here we limit ourselves 282 * to two and hope :-( 283 * We also assume that the text is r-x, and data is rwx or rw-. 284 */ 285 switch (prot) { 286 case (VM_PROT_READ | VM_PROT_EXECUTE): 287 if (epp->ep_tsize != ELF32_NO_ADDR) 288 return ENOEXEC; 289 epp->ep_taddr = vaddr; 290 epp->ep_tsize = size; 291 break; 292 293 case (VM_PROT_READ | VM_PROT_WRITE): 294 case (VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE): 295 if (epp->ep_dsize != ELF32_NO_ADDR) 296 return ENOEXEC; 297 epp->ep_daddr = vaddr; 298 epp->ep_dsize = size; 299 break; 300 301 default: 302 return ENOEXEC; 303 } 304 return 0; 305} 306 307/* 308 * elf_read_from(): 309 * 310 * Read from vnode into buffer at offset. 311 */ 312static int 313elf_read_from(p, vp, off, buf, size) 314 struct vnode *vp; 315 u_long off; 316 struct proc *p; 317 caddr_t buf; 318 int size; 319{ 320 int error; 321 int resid; 322 323 if ((error = vn_rdwr(UIO_READ, vp, buf, size, 324 off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, 325 &resid, p)) != 0) 326 return error; 327 /* 328 * See if we got all of it 329 */ 330 if (resid != 0) 331 return error; 332 return 0; 333} 334 335/* 336 * elf_load_file(): 337 * 338 * Load a file (interpreter/library) pointed to by path 339 * [stolen from coff_load_shlib()]. Made slightly generic 340 * so it might be used externally. 341 */ 342int 343elf_load_file(p, path, vcset, entry, ap, last) 344 struct proc *p; 345 char *path; 346 struct exec_vmcmd_set *vcset; 347 u_long *entry; 348 struct elf_args *ap; 349 u_long *last; 350{ 351 int error, i; 352 struct nameidata nd; 353 Elf32_Ehdr eh; 354 Elf32_Phdr *ph = NULL; 355 u_long phsize; 356 char *bp = NULL; 357 u_long addr = *last; 358 359 bp = path; 360 /* 361 * 1. open file 362 * 2. read filehdr 363 * 3. map text, data, and bss out of it using VM_* 364 */ 365 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, p); 366 if ((error = namei(&nd)) != 0) { 367 return error; 368 } 369 if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh, 370 sizeof(eh))) != 0) 371 goto bad; 372 373 if ((error = elf_check_header(&eh, Elf32_et_dyn)) != 0) 374 goto bad; 375 376 phsize = eh.e_phnum * sizeof(Elf32_Phdr); 377 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 378 379 if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff, 380 (caddr_t) ph, phsize)) != 0) 381 goto bad; 382 383 /* 384 * Load all the necessary sections 385 */ 386 for (i = 0; i < eh.e_phnum; i++) { 387 u_long size = 0; 388 int prot = 0; 389 390 switch (ph[i].p_type) { 391 case Elf32_pt_load: 392 elf_load_psection(vcset, nd.ni_vp, &ph[i], &addr, 393 &size, &prot); 394 /* Assume that the text segment is r-x only */ 395 if ((prot & PROT_WRITE) == 0) { 396 *entry = addr + eh.e_entry; 397 ap->arg_interp = addr; 398 } 399 addr += size; 400 break; 401 402 case Elf32_pt_dynamic: 403 case Elf32_pt_phdr: 404 case Elf32_pt_note: 405 break; 406 407 default: 408 break; 409 } 410 } 411 412bad: 413 if (ph != NULL) 414 free((char *) ph, M_TEMP); 415 416 *last = addr; 417 vrele(nd.ni_vp); 418 return error; 419} 420 421/* 422 * exec_elf_makecmds(): Prepare an Elf binary's exec package 423 * 424 * First, set of the various offsets/lengths in the exec package. 425 * 426 * Then, mark the text image busy (so it can be demand paged) or error 427 * out if this is not possible. Finally, set up vmcmds for the 428 * text, data, bss, and stack segments. 429 * 430 * XXX no demand paging (yet?) 431 */ 432int 433exec_elf_makecmds(p, epp) 434 struct proc *p; 435 struct exec_package *epp; 436{ 437 Elf32_Ehdr *eh = epp->ep_hdr; 438 Elf32_Phdr *ph, *pp; 439 int error, i, n; 440 char interp[MAXPATHLEN]; 441 u_long pos = 0, phsize; 442 443 if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr)) 444 return ENOEXEC; 445 446 if (elf_check_header(eh, Elf32_et_exec)) 447 return ENOEXEC; 448 449 /* 450 * check if vnode is in open for writing, because we want to 451 * demand-page out of it. if it is, don't do it, for various 452 * reasons 453 */ 454 if (epp->ep_vp->v_writecount != 0) { 455#ifdef DIAGNOSTIC 456 if (epp->ep_vp->v_flag & VTEXT) 457 panic("exec: a VTEXT vnode has writecount != 0\n"); 458#endif 459 return ETXTBSY; 460 } 461 /* 462 * Allocate space to hold all the program headers, and read them 463 * from the file 464 */ 465 phsize = eh->e_phnum * sizeof(Elf32_Phdr); 466 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 467 468 if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff, 469 (caddr_t) ph, phsize)) != 0) 470 goto bad; 471 472 epp->ep_tsize = ELF32_NO_ADDR; 473 epp->ep_dsize = ELF32_NO_ADDR; 474 475 interp[0] = '\0'; 476 477 for (i = 0; i < eh->e_phnum; i++) { 478 pp = &ph[i]; 479 if (pp->p_type == Elf32_pt_interp) { 480 if (pp->p_filesz >= sizeof(interp)) 481 goto bad; 482 if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset, 483 (caddr_t) interp, pp->p_filesz)) != 0) 484 goto bad; 485 break; 486 } 487 } 488 489 /* 490 * On the same architecture, we may be emulating different systems. 491 * See which one will accept this executable. This currently only 492 * applies to Linux and SVR4 on the i386. 493 * 494 * Probe functions would normally see if the interpreter (if any) 495 * exists. Emulation packages may possibly replace the interpreter in 496 * interp[] with a changed path (/emul/xxx/<path>), and also 497 * set the ep_emul field in the exec package structure. 498 */ 499 if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) { 500 error = ENOEXEC; 501 for (i = 0; i < n && error; i++) 502 error = elf_probe_funcs[i](p, epp, interp, &pos); 503 504 if (error) 505 goto bad; 506 } 507 508 /* 509 * Load all the necessary sections 510 */ 511 for (i = 0; i < eh->e_phnum; i++) { 512 u_long addr = ELF32_NO_ADDR, size = 0; 513 int prot = 0; 514 515 pp = &ph[i]; 516 517 switch (ph[i].p_type) { 518 case Elf32_pt_load: 519 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 520 &ph[i], &addr, &size, &prot); 521 if ((error = elf_set_segment(epp, addr, size, 522 prot)) != 0) 523 goto bad; 524 break; 525 526 case Elf32_pt_shlib: 527 error = ENOEXEC; 528 goto bad; 529 530 case Elf32_pt_interp: 531 /* Already did this one */ 532 case Elf32_pt_dynamic: 533 case Elf32_pt_phdr: 534 case Elf32_pt_note: 535 break; 536 537 default: 538 /* 539 * Not fatal, we don't need to understand everything 540 * :-) 541 */ 542 break; 543 } 544 } 545 546 /* 547 * Check if we found a dynamically linked binary and arrange to load 548 * it's interpreter 549 */ 550 if (interp[0]) { 551 struct elf_args *ap; 552 553 ap = (struct elf_args *) malloc(sizeof(struct elf_args), 554 M_TEMP, M_WAITOK); 555 if ((error = elf_load_file(p, interp, &epp->ep_vmcmds, 556 &epp->ep_entry, ap, &pos)) != 0) { 557 free((char *) ap, M_TEMP); 558 goto bad; 559 } 560 /* Arrange to load the program headers. */ 561 pos = ELF_ALIGN(pos + NBPG, NBPG); 562 ap->arg_phaddr = pos; 563 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, phsize, 564 pos, epp->ep_vp, eh->e_phoff, 565 VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE); 566 pos += phsize; 567 568 ap->arg_phentsize = eh->e_phentsize; 569 ap->arg_phnum = eh->e_phnum; 570 ap->arg_entry = eh->e_entry; 571 572 epp->ep_emul_arg = ap; 573 } else 574 epp->ep_entry = eh->e_entry; 575 576 free((char *) ph, M_TEMP); 577 epp->ep_vp->v_flag |= VTEXT; 578 return exec_aout_setup_stack(p, epp); 579 580bad: 581 free((char *) ph, M_TEMP); 582 kill_vmcmds(&epp->ep_vmcmds); 583 return ENOEXEC; 584} 585