1 /* $OpenBSD: exec_elf.c,v 1.4 1996/04/18 15:58:33 niklas Exp $ */ 2 /* $NetBSD: exec_elf.c,v 1.6 1996/02/09 18:59:18 christos Exp $ */ 3 4 /* 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 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/kernel.h> 35 #include <sys/proc.h> 36 #include <sys/malloc.h> 37 #include <sys/namei.h> 38 #include <sys/vnode.h> 39 #include <sys/exec.h> 40 #include <sys/exec_elf.h> 41 42 #include <sys/mman.h> 43 #include <vm/vm.h> 44 #include <vm/vm_param.h> 45 #include <vm/vm_map.h> 46 47 #include <machine/cpu.h> 48 #include <machine/reg.h> 49 #include <machine/exec.h> 50 51 #ifdef COMPAT_LINUX 52 #include <compat/linux/linux_exec.h> 53 #endif 54 55 #ifdef COMPAT_SVR4 56 #include <compat/svr4/svr4_exec.h> 57 #endif 58 59 int (*elf_probe_funcs[]) __P((struct proc *, struct exec_package *, 60 char *, u_long *)) = { 61 #ifdef COMPAT_SVR4 62 svr4_elf_probe, 63 #endif 64 #ifdef COMPAT_LINUX 65 linux_elf_probe 66 #endif 67 }; 68 69 int elf_check_header __P((Elf32_Ehdr *, int)); 70 int elf_load_file __P((struct proc *, char *, struct exec_vmcmd_set *, 71 u_long *, struct elf_args *, u_long *)); 72 73 static int elf_read_from __P((struct proc *, struct vnode *, u_long, 74 caddr_t, int)); 75 static void elf_load_psection __P((struct exec_vmcmd_set *, 76 struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *)); 77 78 #define ELF_ALIGN(a, b) ((a) & ~((b) - 1)) 79 80 /* 81 * Copy arguments onto the stack in the normal way, but add some 82 * extra information in case of dynamic binding. 83 */ 84 void * 85 elf_copyargs(pack, arginfo, stack, argp) 86 struct exec_package *pack; 87 struct ps_strings *arginfo; 88 void *stack; 89 void *argp; 90 { 91 size_t len; 92 AuxInfo ai[ELF_AUX_ENTRIES], *a; 93 struct elf_args *ap; 94 95 stack = copyargs(pack, arginfo, stack, argp); 96 if (!stack) 97 return NULL; 98 99 /* 100 * Push extra arguments on the stack needed by dynamically 101 * linked binaries 102 */ 103 if ((ap = (struct elf_args *) pack->ep_emul_arg)) { 104 a = ai; 105 106 a->au_id = AUX_phdr; 107 a->au_v = ap->arg_phaddr; 108 a++; 109 110 a->au_id = AUX_phent; 111 a->au_v = ap->arg_phentsize; 112 a++; 113 114 a->au_id = AUX_phnum; 115 a->au_v = ap->arg_phnum; 116 a++; 117 118 a->au_id = AUX_pagesz; 119 a->au_v = NBPG; 120 a++; 121 122 a->au_id = AUX_base; 123 a->au_v = ap->arg_interp; 124 a++; 125 126 a->au_id = AUX_flags; 127 a->au_v = 0; 128 a++; 129 130 a->au_id = AUX_entry; 131 a->au_v = ap->arg_entry; 132 a++; 133 134 a->au_id = AUX_null; 135 a->au_v = 0; 136 a++; 137 138 free((char *) ap, M_TEMP); 139 len = ELF_AUX_ENTRIES * sizeof (AuxInfo); 140 if (copyout(ai, stack, len)) 141 return NULL; 142 stack += len; 143 } 144 return stack; 145 } 146 147 /* 148 * elf_check_header(): 149 * 150 * Check header for validity; return 0 of ok ENOEXEC if error 151 * 152 * XXX machine type needs to be moved to <machine/param.h> so 153 * just one comparison can be done. Unfortunately, there is both 154 * em_486 and em_386, so this would not work on the i386. 155 */ 156 int 157 elf_check_header(eh, type) 158 Elf32_Ehdr *eh; 159 int type; 160 { 161 162 if (bcmp(eh->e_ident, Elf32_e_ident, Elf32_e_siz) != 0) 163 return ENOEXEC; 164 165 switch (eh->e_machine) { 166 /* XXX */ 167 #ifdef i386 168 case Elf32_em_386: 169 case Elf32_em_486: 170 #endif 171 #ifdef sparc 172 case Elf32_em_sparc: 173 #endif 174 break; 175 176 default: 177 return ENOEXEC; 178 } 179 180 if (eh->e_type != type) 181 return ENOEXEC; 182 183 return 0; 184 } 185 186 /* 187 * elf_load_psection(): 188 * 189 * Load a psection at the appropriate address 190 */ 191 static void 192 elf_load_psection(vcset, vp, ph, addr, size, prot) 193 struct exec_vmcmd_set *vcset; 194 struct vnode *vp; 195 Elf32_Phdr *ph; 196 u_long *addr; 197 u_long *size; 198 int *prot; 199 { 200 u_long uaddr, msize, rm, rf; 201 long diff, offset; 202 203 /* 204 * If the user specified an address, then we load there. 205 */ 206 if (*addr != ELF32_NO_ADDR) { 207 if (ph->p_align > 1) { 208 *addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align); 209 uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align); 210 } else 211 uaddr = ph->p_vaddr; 212 diff = ph->p_vaddr - uaddr; 213 } else { 214 *addr = uaddr = ph->p_vaddr; 215 if (ph->p_align > 1) 216 *addr = ELF_ALIGN(uaddr, ph->p_align); 217 diff = uaddr - *addr; 218 } 219 220 *prot |= (ph->p_flags & Elf32_pf_r) ? VM_PROT_READ : 0; 221 *prot |= (ph->p_flags & Elf32_pf_w) ? VM_PROT_WRITE : 0; 222 *prot |= (ph->p_flags & Elf32_pf_x) ? VM_PROT_EXECUTE : 0; 223 224 offset = ph->p_offset - diff; 225 *size = ph->p_filesz + diff; 226 msize = ph->p_memsz + diff; 227 228 NEW_VMCMD(vcset, vmcmd_map_readvn, *size, *addr, vp, offset, *prot); 229 230 /* 231 * Check if we need to extend the size of the segment 232 */ 233 rm = round_page(*addr + msize); 234 rf = round_page(*addr + *size); 235 236 if (rm != rf) { 237 NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot); 238 *size = msize; 239 } 240 } 241 242 /* 243 * elf_read_from(): 244 * 245 * Read from vnode into buffer at offset. 246 */ 247 static int 248 elf_read_from(p, vp, off, buf, size) 249 struct vnode *vp; 250 u_long off; 251 struct proc *p; 252 caddr_t buf; 253 int size; 254 { 255 int error; 256 int resid; 257 258 if ((error = vn_rdwr(UIO_READ, vp, buf, size, 259 off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, 260 &resid, p)) != 0) 261 return error; 262 /* 263 * See if we got all of it 264 */ 265 if (resid != 0) 266 return ENOEXEC; 267 return 0; 268 } 269 270 /* 271 * elf_load_file(): 272 * 273 * Load a file (interpreter/library) pointed to by path 274 * [stolen from coff_load_shlib()]. Made slightly generic 275 * so it might be used externally. 276 */ 277 int 278 elf_load_file(p, path, vcset, entry, ap, last) 279 struct proc *p; 280 char *path; 281 struct exec_vmcmd_set *vcset; 282 u_long *entry; 283 struct elf_args *ap; 284 u_long *last; 285 { 286 int error, i; 287 struct nameidata nd; 288 Elf32_Ehdr eh; 289 Elf32_Phdr *ph = NULL; 290 u_long phsize; 291 char *bp = NULL; 292 u_long addr = *last; 293 294 bp = path; 295 /* 296 * 1. open file 297 * 2. read filehdr 298 * 3. map text, data, and bss out of it using VM_* 299 */ 300 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, p); 301 if ((error = namei(&nd)) != 0) { 302 return error; 303 } 304 if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh, 305 sizeof(eh))) != 0) 306 goto bad; 307 308 if ((error = elf_check_header(&eh, Elf32_et_dyn)) != 0) 309 goto bad; 310 311 phsize = eh.e_phnum * sizeof(Elf32_Phdr); 312 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 313 314 if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff, 315 (caddr_t) ph, phsize)) != 0) 316 goto bad; 317 318 /* 319 * Load all the necessary sections 320 */ 321 for (i = 0; i < eh.e_phnum; i++) { 322 u_long size = 0; 323 int prot = 0; 324 325 switch (ph[i].p_type) { 326 case Elf32_pt_load: 327 elf_load_psection(vcset, nd.ni_vp, &ph[i], &addr, 328 &size, &prot); 329 /* If entry is within this section it must be text */ 330 if (eh.e_entry >= ph[i].p_vaddr && 331 eh.e_entry < (ph[i].p_vaddr + size)) { 332 *entry = addr + eh.e_entry; 333 ap->arg_interp = addr; 334 } 335 addr += size; 336 break; 337 338 case Elf32_pt_dynamic: 339 case Elf32_pt_phdr: 340 case Elf32_pt_note: 341 break; 342 343 default: 344 break; 345 } 346 } 347 348 bad: 349 if (ph != NULL) 350 free((char *) ph, M_TEMP); 351 352 *last = addr; 353 vrele(nd.ni_vp); 354 return error; 355 } 356 357 /* 358 * exec_elf_makecmds(): Prepare an Elf binary's exec package 359 * 360 * First, set of the various offsets/lengths in the exec package. 361 * 362 * Then, mark the text image busy (so it can be demand paged) or error 363 * out if this is not possible. Finally, set up vmcmds for the 364 * text, data, bss, and stack segments. 365 * 366 * XXX no demand paging (yet?) 367 */ 368 int 369 exec_elf_makecmds(p, epp) 370 struct proc *p; 371 struct exec_package *epp; 372 { 373 Elf32_Ehdr *eh = epp->ep_hdr; 374 Elf32_Phdr *ph, *pp; 375 Elf32_Addr phdr = 0; 376 int error, i, n, nload; 377 char interp[MAXPATHLEN]; 378 u_long pos = 0, phsize; 379 380 if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr)) 381 return ENOEXEC; 382 383 if (elf_check_header(eh, Elf32_et_exec)) 384 return ENOEXEC; 385 386 /* 387 * check if vnode is in open for writing, because we want to 388 * demand-page out of it. if it is, don't do it, for various 389 * reasons 390 */ 391 if (epp->ep_vp->v_writecount != 0) { 392 #ifdef DIAGNOSTIC 393 if (epp->ep_vp->v_flag & VTEXT) 394 panic("exec: a VTEXT vnode has writecount != 0\n"); 395 #endif 396 return ETXTBSY; 397 } 398 /* 399 * Allocate space to hold all the program headers, and read them 400 * from the file 401 */ 402 phsize = eh->e_phnum * sizeof(Elf32_Phdr); 403 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 404 405 if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff, 406 (caddr_t) ph, phsize)) != 0) 407 goto bad; 408 409 epp->ep_tsize = ELF32_NO_ADDR; 410 epp->ep_dsize = ELF32_NO_ADDR; 411 412 interp[0] = '\0'; 413 414 for (i = 0; i < eh->e_phnum; i++) { 415 pp = &ph[i]; 416 if (pp->p_type == Elf32_pt_interp) { 417 if (pp->p_filesz >= sizeof(interp)) 418 goto bad; 419 if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset, 420 (caddr_t) interp, pp->p_filesz)) != 0) 421 goto bad; 422 break; 423 } 424 } 425 426 /* 427 * On the same architecture, we may be emulating different systems. 428 * See which one will accept this executable. This currently only 429 * applies to Linux and SVR4 on the i386. 430 * 431 * Probe functions would normally see if the interpreter (if any) 432 * exists. Emulation packages may possibly replace the interpreter in 433 * interp[] with a changed path (/emul/xxx/<path>), and also 434 * set the ep_emul field in the exec package structure. 435 */ 436 if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) { 437 error = ENOEXEC; 438 for (i = 0; i < n && error; i++) 439 error = elf_probe_funcs[i](p, epp, interp, &pos); 440 441 if (error) 442 goto bad; 443 } 444 445 /* 446 * Load all the necessary sections 447 */ 448 for (i = nload = 0; i < eh->e_phnum; i++) { 449 u_long addr = ELF32_NO_ADDR, size = 0; 450 int prot = 0; 451 452 pp = &ph[i]; 453 454 switch (ph[i].p_type) { 455 case Elf32_pt_load: 456 /* 457 * XXX 458 * Can handle only 2 sections: text and data 459 */ 460 if (nload++ == 2) 461 goto bad; 462 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 463 &ph[i], &addr, &size, &prot); 464 /* 465 * Decide whether it's text or data by looking 466 * at the entry point. 467 */ 468 if (eh->e_entry >= addr && eh->e_entry < (addr + size)){ 469 epp->ep_taddr = addr; 470 epp->ep_tsize = size; 471 } else { 472 epp->ep_daddr = addr; 473 epp->ep_dsize = size; 474 } 475 break; 476 477 case Elf32_pt_shlib: 478 error = ENOEXEC; 479 goto bad; 480 481 case Elf32_pt_interp: 482 /* Already did this one */ 483 case Elf32_pt_dynamic: 484 case Elf32_pt_note: 485 break; 486 487 case Elf32_pt_phdr: 488 /* Note address of program headers (in text segment) */ 489 phdr = pp->p_vaddr; 490 break; 491 492 default: 493 /* 494 * Not fatal, we don't need to understand everything 495 * :-) 496 */ 497 break; 498 } 499 } 500 501 /* 502 * If no position to load the interpreter was set by a probe 503 * function, pick the same address that a non-fixed mmap(0, ..) 504 * would (i.e. something safely out of the way). 505 */ 506 if (pos == ELF32_NO_ADDR) 507 pos = round_page(epp->ep_daddr + MAXDSIZ); 508 509 /* 510 * Check if we found a dynamically linked binary and arrange to load 511 * it's interpreter 512 */ 513 if (interp[0]) { 514 struct elf_args *ap; 515 516 ap = (struct elf_args *) malloc(sizeof(struct elf_args), 517 M_TEMP, M_WAITOK); 518 if ((error = elf_load_file(p, interp, &epp->ep_vmcmds, 519 &epp->ep_entry, ap, &pos)) != 0) { 520 free((char *) ap, M_TEMP); 521 goto bad; 522 } 523 pos += phsize; 524 ap->arg_phaddr = phdr; 525 526 ap->arg_phentsize = eh->e_phentsize; 527 ap->arg_phnum = eh->e_phnum; 528 ap->arg_entry = eh->e_entry; 529 530 epp->ep_emul_arg = ap; 531 } else 532 epp->ep_entry = eh->e_entry; 533 534 #ifdef COMPAT_SVR4_MAP_PAGE_ZERO 535 /* Dell SVR4 maps page zero, yeuch! */ 536 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0, 537 VM_PROT_READ); 538 #endif 539 540 free((char *) ph, M_TEMP); 541 epp->ep_vp->v_flag |= VTEXT; 542 return exec_aout_setup_stack(p, epp); 543 544 bad: 545 free((char *) ph, M_TEMP); 546 kill_vmcmds(&epp->ep_vmcmds); 547 return ENOEXEC; 548 } 549