1 /* $NetBSD: rumpuser_dl.c,v 1.5 2010/12/30 15:47:30 pooka Exp $ */ 2 3 /* 4 * Copyright (c) 2009 Antti Kantee. All Rights Reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * Load all module link sets and feed symbol table to the kernel. 30 * Called during rump bootstrap. 31 */ 32 33 #include <sys/cdefs.h> 34 __RCSID("$NetBSD: rumpuser_dl.c,v 1.5 2010/12/30 15:47:30 pooka Exp $"); 35 36 #include <sys/types.h> 37 #include <sys/time.h> 38 39 #include <assert.h> 40 #include <dlfcn.h> 41 #include <elf.h> 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <link.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 50 #include <rump/rumpuser.h> 51 52 #if defined(__ELF__) && (defined(__NetBSD__) || defined(__FreeBSD__) \ 53 || (defined(__sun__) && defined(__svr4__))) 54 static size_t symtabsize = 0, strtabsize = 0; 55 static size_t symtaboff = 0, strtaboff = 0; 56 static uint8_t *symtab = NULL; 57 static char *strtab = NULL; 58 static unsigned char eident; 59 60 static void * 61 reservespace(void *store, size_t *storesize, 62 size_t storeoff, size_t required) 63 { 64 size_t chunk, newsize; 65 66 assert(storeoff <= *storesize); 67 chunk = *storesize - storeoff; 68 69 if (chunk >= required) 70 return store; 71 72 newsize = *storesize + ((size_t)required - chunk); 73 store = realloc(store, newsize); 74 if (store == NULL) { 75 return NULL; 76 } 77 *((uint8_t *)store + storeoff) = '\0'; 78 *storesize = newsize; 79 80 return store; 81 } 82 83 /* 84 * Macros to make handling elf32/64 in the code a little saner. 85 */ 86 87 #define DYNn_GETMEMBER(base, n, thevar, result) \ 88 do { \ 89 if (eident == ELFCLASS32) { \ 90 Elf32_Dyn *dyn = base; \ 91 /*LINTED*/ \ 92 result = dyn[n].thevar; \ 93 } else { \ 94 Elf64_Dyn *dyn = base; \ 95 /*LINTED*/ \ 96 result = dyn[n].thevar; \ 97 } \ 98 } while (/*CONSTCOND*/0) 99 100 #define SYMn_GETMEMBER(base, n, thevar, result) \ 101 do { \ 102 if (eident == ELFCLASS32) { \ 103 const Elf32_Sym *sym = base; \ 104 /*LINTED*/ \ 105 result = sym[n].thevar; \ 106 } else { \ 107 const Elf64_Sym *sym = base; \ 108 /*LINTED*/ \ 109 result = sym[n].thevar; \ 110 } \ 111 } while (/*CONSTCOND*/0) 112 113 #define SYMn_SETMEMBER(base, n, thevar, value) \ 114 do { \ 115 if (eident == ELFCLASS32) { \ 116 Elf32_Sym *sym = base; \ 117 /*LINTED*/ \ 118 sym[n].thevar = value; \ 119 } else { \ 120 Elf64_Sym *sym = base; \ 121 /*LINTED*/ \ 122 sym[n].thevar = value; \ 123 } \ 124 } while (/*CONSTCOND*/0) 125 126 #define GETVECWORDn(base, n, result) \ 127 do { \ 128 if (eident == ELFCLASS32) { \ 129 Elf32_Word *vec = base; \ 130 result = vec[n]; \ 131 } else { \ 132 Elf64_Word *vec = base; \ 133 result = vec[n]; \ 134 } \ 135 } while (/*CONSTCOND*/0) 136 137 #define SYM_GETSIZE() ((eident==ELFCLASS32)?sizeof(Elf32_Sym):sizeof(Elf64_Sym)) 138 139 static int 140 getsymbols(struct link_map *map) 141 { 142 char *str_base; 143 void *syms_base = NULL; /* XXXgcc */ 144 size_t curstrsize; 145 void *ed_base; 146 uint64_t ed_tag; 147 size_t cursymcount; 148 unsigned i; 149 150 if (map->l_addr) { 151 if (memcmp(map->l_addr, ELFMAG, SELFMAG) != 0) 152 return ENOEXEC; 153 eident = *(unsigned char *)(map->l_addr + EI_CLASS); 154 if (eident != ELFCLASS32 && eident != ELFCLASS64) 155 return ENOEXEC; 156 } 157 158 /* 159 * ok, we probably have only the main object. instead of going 160 * to disk and reading the ehdr, just try to guess the size. 161 */ 162 if (eident == 0) { 163 if (/*CONSTCOND*/sizeof(void *) == 4) 164 eident = ELFCLASS32; 165 else 166 eident = ELFCLASS64; 167 } 168 169 /* 170 * Find symtab and strtab and their sizes. 171 */ 172 str_base = NULL; 173 curstrsize = 0; 174 cursymcount = 0; 175 ed_base = map->l_ld; 176 DYNn_GETMEMBER(ed_base, 0, d_tag, ed_tag); 177 for (i = 0; ed_tag != DT_NULL;) { 178 uintptr_t edptr; 179 size_t edval; 180 void *hashtab; 181 182 switch (ed_tag) { 183 case DT_SYMTAB: 184 DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr); 185 syms_base = map->l_addr + edptr; 186 break; 187 case DT_STRTAB: 188 DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr); 189 str_base = map->l_addr + edptr; 190 break; 191 case DT_STRSZ: 192 DYNn_GETMEMBER(ed_base, i, d_un.d_val, edval); 193 curstrsize = edval; 194 break; 195 case DT_HASH: 196 DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr); 197 hashtab = map->l_addr + edptr; 198 GETVECWORDn(hashtab, 1, cursymcount); 199 break; 200 case DT_SYMENT: 201 DYNn_GETMEMBER(ed_base, i, d_un.d_val, edval); 202 assert(edval == SYM_GETSIZE()); 203 break; 204 default: 205 break; 206 } 207 i++; 208 DYNn_GETMEMBER(ed_base, i, d_tag, ed_tag); 209 } 210 211 if (str_base == NULL || syms_base == NULL || 212 curstrsize == 0 || cursymcount == 0) { 213 fprintf(stderr, "could not find strtab, symtab or their sizes " 214 "in %s\n", map->l_name); 215 return ENOEXEC; 216 } 217 218 /* 219 * Make sure we have enough space for the contents of the symbol 220 * and string tables we are currently processing. The total used 221 * space will be smaller due to undefined symbols we are not 222 * interested in. 223 */ 224 symtab = reservespace(symtab, &symtabsize, 225 symtaboff, cursymcount * SYM_GETSIZE()); 226 strtab = reservespace(strtab, &strtabsize, strtaboff, curstrsize); 227 if (symtab == NULL || strtab == NULL) { 228 fprintf(stderr, "failed to reserve memory"); 229 return ENOMEM; 230 } 231 232 /* iterate over all symbols in current symtab */ 233 for (i = 0; i < cursymcount; i++) { 234 const char *cursymname; 235 int shndx, name; 236 uintptr_t value; 237 void *csym; 238 239 SYMn_GETMEMBER(syms_base, i, st_shndx, shndx); 240 SYMn_GETMEMBER(syms_base, i, st_value, value); 241 if (shndx == SHN_UNDEF || value == 0) 242 continue; 243 244 /* get symbol name */ 245 SYMn_GETMEMBER(syms_base, i, st_name, name); 246 cursymname = name + str_base; 247 248 /* 249 * Only accept symbols which are decidedly in 250 * the rump kernel namespace. 251 * XXX: quirks, but they wouldn't matter here 252 */ 253 if (strncmp(cursymname, "rump", 4) != 0 && 254 strncmp(cursymname, "RUMP", 4) != 0 && 255 strncmp(cursymname, "__", 2) != 0) { 256 continue; 257 } 258 259 memcpy(symtab + symtaboff, 260 (const uint8_t *)syms_base + i*SYM_GETSIZE(),SYM_GETSIZE()); 261 262 /* 263 * set name to point at new strtab, offset symbol value 264 * with lib base address. 265 */ 266 csym = symtab + symtaboff; 267 SYMn_SETMEMBER(csym, 0, st_name, strtaboff); 268 SYMn_GETMEMBER(csym, 0, st_value, value); 269 SYMn_SETMEMBER(csym, 0, st_value,(intptr_t)(value+map->l_addr)); 270 symtaboff += SYM_GETSIZE(); 271 272 strcpy(strtab + strtaboff, cursymname); 273 strtaboff += strlen(cursymname)+1; 274 } 275 276 return 0; 277 } 278 279 static void 280 process(const char *soname, rump_modinit_fn domodinit) 281 { 282 void *handle; 283 const struct modinfo *const *mi_start, *const *mi_end; 284 285 if (strstr(soname, "librump") == NULL) 286 return; 287 288 handle = dlopen(soname, RTLD_LAZY); 289 if (handle == NULL) 290 return; 291 292 mi_start = dlsym(handle, "__start_link_set_modules"); 293 if (!mi_start) 294 goto out; 295 mi_end = dlsym(handle, "__stop_link_set_modules"); 296 if (!mi_end) 297 goto out; 298 299 domodinit(mi_start, (size_t)(mi_end-mi_start)); 300 301 out: 302 dlclose(handle); 303 } 304 305 /* 306 * Get the linkmap from the dynlinker. Try to load kernel modules 307 * from all objects in the linkmap. 308 */ 309 void 310 rumpuser_dl_bootstrap(rump_modinit_fn domodinit, 311 rump_symload_fn symload) 312 { 313 struct link_map *map, *origmap; 314 int error; 315 316 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &origmap) == -1) { 317 fprintf(stderr, "warning: rumpuser module bootstrap " 318 "failed: %s\n", dlerror()); 319 return; 320 } 321 /* 322 * Process last->first because that's the most probable 323 * order for dependencies 324 */ 325 for (; origmap->l_next; origmap = origmap->l_next) 326 continue; 327 328 /* 329 * Build symbol table to hand to the rump kernel. Do this by 330 * iterating over all rump libraries and collecting symbol 331 * addresses and relocation info. 332 */ 333 error = 0; 334 for (map = origmap; map && !error; map = map->l_prev) { 335 if (strstr(map->l_name, "librump") != NULL) 336 error = getsymbols(map); 337 /* this should be the main object */ 338 else if (map->l_addr == NULL && map->l_prev == NULL) 339 error = getsymbols(map); 340 } 341 342 if (error == 0) { 343 void *trimmedsym, *trimmedstr; 344 345 /* 346 * Allocate optimum-sized memory for storing tables 347 * and feed to kernel. If memory allocation fails, 348 * just give the ones with extra context (although 349 * I'm pretty sure we'll die moments later due to 350 * memory running out). 351 */ 352 if ((trimmedsym = malloc(symtaboff)) != NULL) { 353 memcpy(trimmedsym, symtab, symtaboff); 354 } else { 355 trimmedsym = symtab; 356 symtab = NULL; 357 } 358 if ((trimmedstr = malloc(strtaboff)) != NULL) { 359 memcpy(trimmedstr, strtab, strtaboff); 360 } else { 361 trimmedstr = strtab; 362 strtab = NULL; 363 } 364 symload(trimmedsym, symtaboff, trimmedstr, strtaboff); 365 } 366 free(symtab); 367 free(strtab); 368 369 /* 370 * Next, load modules from dynlibs. 371 */ 372 for (map = origmap; map; map = map->l_prev) 373 process(map->l_name, domodinit); 374 } 375 376 void 377 rumpuser_dl_component_init(int type, rump_component_init_fn compinit) 378 { 379 struct link_map *map; 380 381 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map) == -1) { 382 fprintf(stderr, "warning: rumpuser module bootstrap " 383 "failed: %s\n", dlerror()); 384 return; 385 } 386 387 for (; map->l_next; map = map->l_next) 388 continue; 389 for (; map; map = map->l_prev) { 390 if (strstr(map->l_name, "librump") != NULL) { 391 void *handle; 392 struct rump_component **rc, **rc_end; 393 394 handle = dlopen(map->l_name, RTLD_LAZY); 395 if (handle == NULL) 396 continue; 397 398 rc = dlsym(handle, 399 "__start_link_set_rump_components"); 400 if (!rc) 401 goto loop; 402 rc_end = dlsym(handle, 403 "__stop_link_set_rump_components"); 404 if (!rc_end) 405 goto loop; 406 407 for (; rc < rc_end; rc++) 408 compinit(*rc, type); 409 assert(rc == rc_end); 410 loop: 411 dlclose(handle); 412 } 413 } 414 } 415 #else 416 void 417 rumpuser_dl_bootstrap(rump_modinit_fn domodinit, 418 rump_symload_fn symload) 419 { 420 421 fprintf(stderr, "Warning, dlinfo() unsupported on host?\n"); 422 } 423 424 void 425 rumpuser_dl_component_init(int type, rump_component_init_fn compinit) 426 { 427 428 fprintf(stderr, "Warning, dlinfo() unsupported on host?\n"); 429 } 430 #endif 431 432 void * 433 rumpuser_dl_globalsym(const char *symname) 434 { 435 436 return dlsym(RTLD_DEFAULT, symname); 437 } 438