exec_elf.c revision 1.7
1 /* $NetBSD: exec_elf.c,v 1.7 1996/06/13 18:35:25 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 58 int (*elf_probe_funcs[]) __P((struct proc *, struct exec_package *, 59 Elf32_Ehdr *, char *, u_long *)) = { 60 #ifdef COMPAT_LINUX 61 linux_elf_probe, 62 #endif 63 #ifdef COMPAT_SVR4 64 svr4_elf_probe, 65 #endif 66 }; 67 68 int elf_check_header __P((Elf32_Ehdr *, int)); 69 int elf_load_file __P((struct proc *, char *, struct exec_vmcmd_set *, 70 u_long *, struct elf_args *, u_long *)); 71 72 static void elf_load_psection __P((struct exec_vmcmd_set *, 73 struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *)); 74 75 #define ELF_ALIGN(a, b) ((a) & ~((b) - 1)) 76 77 /* 78 * Copy arguments onto the stack in the normal way, but add some 79 * extra information in case of dynamic binding. 80 */ 81 void * 82 elf_copyargs(pack, arginfo, stack, argp) 83 struct exec_package *pack; 84 struct ps_strings *arginfo; 85 void *stack; 86 void *argp; 87 { 88 size_t len; 89 AuxInfo ai[ELF_AUX_ENTRIES], *a; 90 struct elf_args *ap; 91 92 stack = copyargs(pack, arginfo, stack, argp); 93 if (!stack) 94 return NULL; 95 96 /* 97 * Push extra arguments on the stack needed by dynamically 98 * linked binaries 99 */ 100 if ((ap = (struct elf_args *) pack->ep_emul_arg)) { 101 a = ai; 102 103 a->au_id = AUX_phdr; 104 a->au_v = ap->arg_phaddr; 105 a++; 106 107 a->au_id = AUX_phent; 108 a->au_v = ap->arg_phentsize; 109 a++; 110 111 a->au_id = AUX_phnum; 112 a->au_v = ap->arg_phnum; 113 a++; 114 115 a->au_id = AUX_pagesz; 116 a->au_v = NBPG; 117 a++; 118 119 a->au_id = AUX_base; 120 a->au_v = ap->arg_interp; 121 a++; 122 123 a->au_id = AUX_flags; 124 a->au_v = 0; 125 a++; 126 127 a->au_id = AUX_entry; 128 a->au_v = ap->arg_entry; 129 a++; 130 131 a->au_id = AUX_null; 132 a->au_v = 0; 133 a++; 134 135 free((char *) ap, M_TEMP); 136 len = ELF_AUX_ENTRIES * sizeof (AuxInfo); 137 if (copyout(ai, stack, len)) 138 return NULL; 139 stack += len; 140 } 141 return stack; 142 } 143 144 /* 145 * elf_check_header(): 146 * 147 * Check header for validity; return 0 of ok ENOEXEC if error 148 * 149 * XXX machine type needs to be moved to <machine/param.h> so 150 * just one comparison can be done. Unfortunately, there is both 151 * em_486 and em_386, so this would not work on the i386. 152 */ 153 int 154 elf_check_header(eh, type) 155 Elf32_Ehdr *eh; 156 int type; 157 { 158 159 if (bcmp(eh->e_ident, Elf32_e_ident, Elf32_e_siz) != 0) 160 return ENOEXEC; 161 162 switch (eh->e_machine) { 163 /* XXX */ 164 #ifdef i386 165 case Elf32_em_386: 166 case Elf32_em_486: 167 #endif 168 #ifdef sparc 169 case Elf32_em_sparc: 170 #endif 171 break; 172 173 default: 174 return ENOEXEC; 175 } 176 177 if (eh->e_type != type) 178 return ENOEXEC; 179 180 return 0; 181 } 182 183 /* 184 * elf_load_psection(): 185 * 186 * Load a psection at the appropriate address 187 */ 188 static void 189 elf_load_psection(vcset, vp, ph, addr, size, prot) 190 struct exec_vmcmd_set *vcset; 191 struct vnode *vp; 192 Elf32_Phdr *ph; 193 u_long *addr; 194 u_long *size; 195 int *prot; 196 { 197 u_long uaddr, msize, rm, rf; 198 long diff, offset; 199 200 /* 201 * If the user specified an address, then we load there. 202 */ 203 if (*addr != ELF32_NO_ADDR) { 204 if (ph->p_align > 1) { 205 *addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align); 206 uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align); 207 } else 208 uaddr = ph->p_vaddr; 209 diff = ph->p_vaddr - uaddr; 210 } else { 211 *addr = uaddr = ph->p_vaddr; 212 if (ph->p_align > 1) 213 *addr = ELF_ALIGN(uaddr, ph->p_align); 214 diff = uaddr - *addr; 215 } 216 217 *prot |= (ph->p_flags & Elf32_pf_r) ? VM_PROT_READ : 0; 218 *prot |= (ph->p_flags & Elf32_pf_w) ? VM_PROT_WRITE : 0; 219 *prot |= (ph->p_flags & Elf32_pf_x) ? VM_PROT_EXECUTE : 0; 220 221 offset = ph->p_offset - diff; 222 *size = ph->p_filesz + diff; 223 msize = ph->p_memsz + diff; 224 225 NEW_VMCMD(vcset, vmcmd_map_readvn, *size, *addr, vp, offset, *prot); 226 227 /* 228 * Check if we need to extend the size of the segment 229 */ 230 rm = round_page(*addr + msize); 231 rf = round_page(*addr + *size); 232 233 if (rm != rf) { 234 NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot); 235 *size = msize; 236 } 237 } 238 239 /* 240 * elf_read_from(): 241 * 242 * Read from vnode into buffer at offset. 243 */ 244 int 245 elf_read_from(p, vp, off, buf, size) 246 struct vnode *vp; 247 u_long off; 248 struct proc *p; 249 caddr_t buf; 250 int size; 251 { 252 int error; 253 int resid; 254 255 if ((error = vn_rdwr(UIO_READ, vp, buf, size, 256 off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, 257 &resid, p)) != 0) 258 return error; 259 /* 260 * See if we got all of it 261 */ 262 if (resid != 0) 263 return ENOEXEC; 264 return 0; 265 } 266 267 /* 268 * elf_load_file(): 269 * 270 * Load a file (interpreter/library) pointed to by path 271 * [stolen from coff_load_shlib()]. Made slightly generic 272 * so it might be used externally. 273 */ 274 int 275 elf_load_file(p, path, vcset, entry, ap, last) 276 struct proc *p; 277 char *path; 278 struct exec_vmcmd_set *vcset; 279 u_long *entry; 280 struct elf_args *ap; 281 u_long *last; 282 { 283 int error, i; 284 struct nameidata nd; 285 Elf32_Ehdr eh; 286 Elf32_Phdr *ph = NULL; 287 u_long phsize; 288 char *bp = NULL; 289 u_long addr = *last; 290 291 bp = path; 292 /* 293 * 1. open file 294 * 2. read filehdr 295 * 3. map text, data, and bss out of it using VM_* 296 */ 297 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, p); 298 if ((error = namei(&nd)) != 0) { 299 return error; 300 } 301 if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh, 302 sizeof(eh))) != 0) 303 goto bad; 304 305 if ((error = elf_check_header(&eh, Elf32_et_dyn)) != 0) 306 goto bad; 307 308 phsize = eh.e_phnum * sizeof(Elf32_Phdr); 309 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 310 311 if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff, 312 (caddr_t) ph, phsize)) != 0) 313 goto bad; 314 315 /* 316 * Load all the necessary sections 317 */ 318 for (i = 0; i < eh.e_phnum; i++) { 319 u_long size = 0; 320 int prot = 0; 321 322 switch (ph[i].p_type) { 323 case Elf32_pt_load: 324 elf_load_psection(vcset, nd.ni_vp, &ph[i], &addr, 325 &size, &prot); 326 /* If entry is within this section it must be text */ 327 if (eh.e_entry >= ph[i].p_vaddr && 328 eh.e_entry < (ph[i].p_vaddr + size)) { 329 *entry = addr + eh.e_entry; 330 ap->arg_interp = addr; 331 } 332 addr += size; 333 break; 334 335 case Elf32_pt_dynamic: 336 case Elf32_pt_phdr: 337 case Elf32_pt_note: 338 break; 339 340 default: 341 break; 342 } 343 } 344 345 bad: 346 if (ph != NULL) 347 free((char *) ph, M_TEMP); 348 349 *last = addr; 350 vrele(nd.ni_vp); 351 return error; 352 } 353 354 /* 355 * exec_elf_makecmds(): Prepare an Elf binary's exec package 356 * 357 * First, set of the various offsets/lengths in the exec package. 358 * 359 * Then, mark the text image busy (so it can be demand paged) or error 360 * out if this is not possible. Finally, set up vmcmds for the 361 * text, data, bss, and stack segments. 362 * 363 * XXX no demand paging (yet?) 364 */ 365 int 366 exec_elf_makecmds(p, epp) 367 struct proc *p; 368 struct exec_package *epp; 369 { 370 Elf32_Ehdr *eh = epp->ep_hdr; 371 Elf32_Phdr *ph, *pp; 372 Elf32_Addr phdr = 0; 373 int error, i, n, nload; 374 char interp[MAXPATHLEN]; 375 u_long pos = 0, phsize; 376 377 if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr)) 378 return ENOEXEC; 379 380 if (elf_check_header(eh, Elf32_et_exec)) 381 return ENOEXEC; 382 383 /* 384 * check if vnode is in open for writing, because we want to 385 * demand-page out of it. if it is, don't do it, for various 386 * reasons 387 */ 388 if (epp->ep_vp->v_writecount != 0) { 389 #ifdef DIAGNOSTIC 390 if (epp->ep_vp->v_flag & VTEXT) 391 panic("exec: a VTEXT vnode has writecount != 0\n"); 392 #endif 393 return ETXTBSY; 394 } 395 /* 396 * Allocate space to hold all the program headers, and read them 397 * from the file 398 */ 399 phsize = eh->e_phnum * sizeof(Elf32_Phdr); 400 ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK); 401 402 if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff, 403 (caddr_t) ph, phsize)) != 0) 404 goto bad; 405 406 epp->ep_tsize = ELF32_NO_ADDR; 407 epp->ep_dsize = ELF32_NO_ADDR; 408 409 interp[0] = '\0'; 410 411 for (i = 0; i < eh->e_phnum; i++) { 412 pp = &ph[i]; 413 if (pp->p_type == Elf32_pt_interp) { 414 if (pp->p_filesz >= sizeof(interp)) 415 goto bad; 416 if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset, 417 (caddr_t) interp, pp->p_filesz)) != 0) 418 goto bad; 419 break; 420 } 421 } 422 423 /* 424 * On the same architecture, we may be emulating different systems. 425 * See which one will accept this executable. This currently only 426 * applies to Linux and SVR4 on the i386. 427 * 428 * Probe functions would normally see if the interpreter (if any) 429 * exists. Emulation packages may possibly replace the interpreter in 430 * interp[] with a changed path (/emul/xxx/<path>), and also 431 * set the ep_emul field in the exec package structure. 432 */ 433 if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) { 434 error = ENOEXEC; 435 for (i = 0; i < n && error; i++) 436 error = elf_probe_funcs[i](p, epp, eh, interp, &pos); 437 438 if (error) 439 goto bad; 440 } 441 442 /* 443 * Load all the necessary sections 444 */ 445 for (i = nload = 0; i < eh->e_phnum; i++) { 446 u_long addr = ELF32_NO_ADDR, size = 0; 447 int prot = 0; 448 449 pp = &ph[i]; 450 451 switch (ph[i].p_type) { 452 case Elf32_pt_load: 453 /* 454 * XXX 455 * Can handle only 2 sections: text and data 456 */ 457 if (nload++ == 2) 458 goto bad; 459 elf_load_psection(&epp->ep_vmcmds, epp->ep_vp, 460 &ph[i], &addr, &size, &prot); 461 /* 462 * Decide whether it's text or data by looking 463 * at the entry point. 464 */ 465 if (eh->e_entry >= addr && eh->e_entry < (addr + size)){ 466 epp->ep_taddr = addr; 467 epp->ep_tsize = size; 468 } else { 469 epp->ep_daddr = addr; 470 epp->ep_dsize = size; 471 } 472 break; 473 474 case Elf32_pt_shlib: 475 error = ENOEXEC; 476 goto bad; 477 478 case Elf32_pt_interp: 479 /* Already did this one */ 480 case Elf32_pt_dynamic: 481 case Elf32_pt_note: 482 break; 483 484 case Elf32_pt_phdr: 485 /* Note address of program headers (in text segment) */ 486 phdr = pp->p_vaddr; 487 break; 488 489 default: 490 /* 491 * Not fatal, we don't need to understand everything 492 * :-) 493 */ 494 break; 495 } 496 } 497 498 /* 499 * If no position to load the interpreter was set by a probe 500 * function, pick the same address that a non-fixed mmap(0, ..) 501 * would (i.e. something safely out of the way). 502 */ 503 if (pos == ELF32_NO_ADDR) 504 pos = round_page(epp->ep_daddr + MAXDSIZ); 505 506 /* 507 * Check if we found a dynamically linked binary and arrange to load 508 * it's interpreter 509 */ 510 if (interp[0]) { 511 struct elf_args *ap; 512 513 ap = (struct elf_args *) malloc(sizeof(struct elf_args), 514 M_TEMP, M_WAITOK); 515 if ((error = elf_load_file(p, interp, &epp->ep_vmcmds, 516 &epp->ep_entry, ap, &pos)) != 0) { 517 free((char *) ap, M_TEMP); 518 goto bad; 519 } 520 pos += phsize; 521 ap->arg_phaddr = phdr; 522 523 ap->arg_phentsize = eh->e_phentsize; 524 ap->arg_phnum = eh->e_phnum; 525 ap->arg_entry = eh->e_entry; 526 527 epp->ep_emul_arg = ap; 528 } else 529 epp->ep_entry = eh->e_entry; 530 531 free((char *) ph, M_TEMP); 532 epp->ep_vp->v_flag |= VTEXT; 533 return exec_aout_setup_stack(p, epp); 534 535 bad: 536 free((char *) ph, M_TEMP); 537 kill_vmcmds(&epp->ep_vmcmds); 538 return ENOEXEC; 539 } 540
Indexes created Tue Sep 23 07:09:52 GMT 2025