1 /*- 2 * Copyright (c) 2007-2010,2012 Kai Wang 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 #include <sys/queue.h> 29 #include <err.h> 30 #include <gelf.h> 31 #include <stdint.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <string.h> 35 36 #include "elfcopy.h" 37 38 ELFTC_VCSID("$Id: segments.c 3134 2014-12-23 10:43:59Z kaiwang27 $"); 39 40 static void insert_to_inseg_list(struct segment *seg, struct section *sec); 41 42 /* 43 * elfcopy's segment handling is relatively simpler and less powerful than 44 * libbfd. Program headers are modified or copied from input to output objects, 45 * but never re-generated. As a result, if the input object has incorrect 46 * program headers, the output object's program headers will remain incorrect 47 * or become even worse. 48 */ 49 50 /* 51 * Check whether a section is "loadable". If so, add it to the 52 * corresponding segment list(s) and return 1. 53 */ 54 int 55 add_to_inseg_list(struct elfcopy *ecp, struct section *s) 56 { 57 struct segment *seg; 58 int loadable; 59 60 if (ecp->ophnum == 0) 61 return (0); 62 63 /* 64 * Segment is a different view of an ELF object. One segment can 65 * contain one or more sections, and one section can be included 66 * in one or more segments, or not included in any segment at all. 67 * We call those sections which can be found in one or more segments 68 * "loadable" sections, and call the rest "unloadable" sections. 69 * We keep track of "loadable" sections in their containing 70 * segment(s)' v_sec queue. These information are later used to 71 * recalculate the extents of segments, when sections are removed, 72 * for example. 73 */ 74 loadable = 0; 75 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 76 if (s->off < seg->off || (s->vma < seg->addr && !s->pseudo)) 77 continue; 78 if (s->off + s->sz > seg->off + seg->fsz && 79 s->type != SHT_NOBITS) 80 continue; 81 if (s->off + s->sz > seg->off + seg->msz) 82 continue; 83 if (s->vma + s->sz > seg->addr + seg->msz) 84 continue; 85 86 insert_to_inseg_list(seg, s); 87 if (seg->type == PT_LOAD) 88 s->seg = seg; 89 else if (seg->type == PT_TLS) 90 s->seg_tls = seg; 91 s->lma = seg->addr + (s->off - seg->off); 92 loadable = 1; 93 } 94 95 return (loadable); 96 } 97 98 void 99 adjust_addr(struct elfcopy *ecp) 100 { 101 struct section *s, *s0; 102 struct segment *seg; 103 struct sec_action *sac; 104 uint64_t dl, lma, start, end; 105 int found, i; 106 107 /* 108 * Apply VMA and global LMA changes in the first iteration. 109 */ 110 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 111 112 /* Only adjust loadable section's address. */ 113 if (!s->loadable || s->seg == NULL) 114 continue; 115 116 /* Apply global LMA adjustment. */ 117 if (ecp->change_addr != 0) 118 s->lma += ecp->change_addr; 119 120 if (!s->pseudo) { 121 /* Apply global VMA adjustment. */ 122 if (ecp->change_addr != 0) 123 s->vma += ecp->change_addr; 124 125 /* Apply section VMA adjustment. */ 126 sac = lookup_sec_act(ecp, s->name, 0); 127 if (sac == NULL) 128 continue; 129 if (sac->setvma) 130 s->vma = sac->vma; 131 if (sac->vma_adjust != 0) 132 s->vma += sac->vma_adjust; 133 } 134 } 135 136 /* 137 * Apply sections LMA change in the second iteration. 138 */ 139 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 140 141 /* Only adjust loadable section's LMA. */ 142 if (!s->loadable || s->seg == NULL) 143 continue; 144 145 /* 146 * Check if there is a LMA change request for this 147 * section. 148 */ 149 sac = lookup_sec_act(ecp, s->name, 0); 150 if (sac == NULL) 151 continue; 152 if (!sac->setlma && sac->lma_adjust == 0) 153 continue; 154 lma = s->lma; 155 if (sac->setlma) 156 lma = sac->lma; 157 if (sac->lma_adjust != 0) 158 lma += sac->lma_adjust; 159 if (lma == s->lma) 160 continue; 161 162 /* 163 * Check if the LMA change is viable. 164 * 165 * 1. Check if the new LMA is properly aligned accroding to 166 * section alignment. 167 * 168 * 2. Compute the new extent of segment that contains this 169 * section, make sure it doesn't overlap with other 170 * segments. 171 */ 172 #ifdef DEBUG 173 printf("LMA for section %s: %#jx\n", s->name, lma); 174 #endif 175 176 if (lma % s->align != 0) 177 errx(EXIT_FAILURE, "The load address %#jx for " 178 "section %s is not aligned to %ju", 179 (uintmax_t) lma, s->name, s->align); 180 181 if (lma < s->lma) { 182 /* Move section to lower address. */ 183 if (lma < s->lma - s->seg->addr) 184 errx(EXIT_FAILURE, "Not enough space to move " 185 "section %s load address to %#jx", s->name, 186 (uintmax_t) lma); 187 start = lma - (s->lma - s->seg->addr); 188 if (s == s->seg->v_sec[s->seg->nsec - 1]) 189 end = start + s->seg->msz; 190 else 191 end = s->seg->addr + s->seg->msz; 192 193 } else { 194 /* Move section to upper address. */ 195 if (s == s->seg->v_sec[0]) 196 start = lma; 197 else 198 start = s->seg->addr; 199 end = lma + (s->seg->addr + s->seg->msz - s->lma); 200 if (end < start) 201 errx(EXIT_FAILURE, "Not enough space to move " 202 "section %s load address to %#jx", s->name, 203 (uintmax_t) lma); 204 } 205 206 #ifdef DEBUG 207 printf("new extent for segment containing %s: (%#jx,%#jx)\n", 208 s->name, start, end); 209 #endif 210 211 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 212 if (seg == s->seg || seg->type != PT_LOAD) 213 continue; 214 if (start > seg->addr + seg->msz) 215 continue; 216 if (end < seg->addr) 217 continue; 218 errx(EXIT_FAILURE, "The extent of segment containing " 219 "section %s overlaps with segment(%#jx,%#jx)", 220 s->name, seg->addr, seg->addr + seg->msz); 221 } 222 223 /* 224 * Update section LMA and file offset. 225 */ 226 227 if (lma < s->lma) { 228 /* 229 * To move a section to lower load address, we decrease 230 * the load addresses of the section and all the 231 * sections that are before it, and we increase the 232 * file offsets of all the sections that are after it. 233 */ 234 dl = s->lma - lma; 235 for (i = 0; i < s->seg->nsec; i++) { 236 s0 = s->seg->v_sec[i]; 237 s0->lma -= dl; 238 #ifdef DEBUG 239 printf("section %s LMA set to %#jx\n", 240 s0->name, (uintmax_t) s0->lma); 241 #endif 242 if (s0 == s) 243 break; 244 } 245 for (i = i + 1; i < s->seg->nsec; i++) { 246 s0 = s->seg->v_sec[i]; 247 s0->off += dl; 248 #ifdef DEBUG 249 printf("section %s offset set to %#jx\n", 250 s0->name, (uintmax_t) s0->off); 251 #endif 252 } 253 } else { 254 /* 255 * To move a section to upper load address, we increase 256 * the load addresses of the section and all the 257 * sections that are after it, and we increase the 258 * their file offsets too unless the section in question 259 * is the first in its containing segment. 260 */ 261 dl = lma - s->lma; 262 for (i = 0; i < s->seg->nsec; i++) 263 if (s->seg->v_sec[i] == s) 264 break; 265 if (i >= s->seg->nsec) 266 errx(EXIT_FAILURE, "Internal: section `%s' not" 267 " found in its containing segement", 268 s->name); 269 for (; i < s->seg->nsec; i++) { 270 s0 = s->seg->v_sec[i]; 271 s0->lma += dl; 272 #ifdef DEBUG 273 printf("section %s LMA set to %#jx\n", 274 s0->name, (uintmax_t) s0->lma); 275 #endif 276 if (s != s->seg->v_sec[0]) { 277 s0->off += dl; 278 #ifdef DEBUG 279 printf("section %s offset set to %#jx\n", 280 s0->name, (uintmax_t) s0->off); 281 #endif 282 } 283 } 284 } 285 } 286 287 /* 288 * Apply load address padding. 289 */ 290 291 if (ecp->pad_to != 0) { 292 293 /* 294 * Find the section with highest load address. 295 */ 296 297 s = NULL; 298 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 299 if (seg->type != PT_LOAD) 300 continue; 301 for (i = seg->nsec - 1; i >= 0; i--) 302 if (seg->v_sec[i]->type != SHT_NOBITS) 303 break; 304 if (i < 0) 305 continue; 306 if (s == NULL) 307 s = seg->v_sec[i]; 308 else { 309 s0 = seg->v_sec[i]; 310 if (s0->lma > s->lma) 311 s = s0; 312 } 313 } 314 315 if (s == NULL) 316 goto issue_warn; 317 318 /* No need to pad if the pad_to address is lower. */ 319 if (ecp->pad_to <= s->lma + s->sz) 320 goto issue_warn; 321 322 s->pad_sz = ecp->pad_to - (s->lma + s->sz); 323 #ifdef DEBUG 324 printf("pad section %s load to address %#jx by %#jx\n", s->name, 325 (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz); 326 #endif 327 } 328 329 issue_warn: 330 331 /* 332 * Issue a warning if there are VMA/LMA adjust requests for 333 * some nonexistent sections. 334 */ 335 if ((ecp->flags & NO_CHANGE_WARN) == 0) { 336 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) { 337 if (!sac->setvma && !sac->setlma && 338 !sac->vma_adjust && !sac->lma_adjust) 339 continue; 340 found = 0; 341 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 342 if (s->pseudo || s->name == NULL) 343 continue; 344 if (!strcmp(s->name, sac->name)) { 345 found = 1; 346 break; 347 } 348 } 349 if (!found) 350 warnx("cannot find section `%s'", sac->name); 351 } 352 } 353 } 354 355 static void 356 insert_to_inseg_list(struct segment *seg, struct section *sec) 357 { 358 struct section *s; 359 int i; 360 361 seg->nsec++; 362 seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec)); 363 if (seg->v_sec == NULL) 364 err(EXIT_FAILURE, "realloc failed"); 365 366 /* 367 * Sort the section in order of offset. 368 */ 369 370 for (i = seg->nsec - 1; i > 0; i--) { 371 s = seg->v_sec[i - 1]; 372 if (sec->off >= s->off) { 373 seg->v_sec[i] = sec; 374 break; 375 } else 376 seg->v_sec[i] = s; 377 } 378 if (i == 0) 379 seg->v_sec[0] = sec; 380 } 381 382 void 383 setup_phdr(struct elfcopy *ecp) 384 { 385 struct segment *seg; 386 GElf_Phdr iphdr; 387 size_t iphnum; 388 int i; 389 390 if (elf_getphnum(ecp->ein, &iphnum) == 0) 391 errx(EXIT_FAILURE, "elf_getphnum failed: %s", 392 elf_errmsg(-1)); 393 394 ecp->ophnum = ecp->iphnum = iphnum; 395 if (iphnum == 0) 396 return; 397 398 /* If --only-keep-debug is specified, discard all program headers. */ 399 if (ecp->strip == STRIP_NONDEBUG) { 400 ecp->ophnum = 0; 401 return; 402 } 403 404 for (i = 0; (size_t)i < iphnum; i++) { 405 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr) 406 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 407 elf_errmsg(-1)); 408 if ((seg = calloc(1, sizeof(*seg))) == NULL) 409 err(EXIT_FAILURE, "calloc failed"); 410 seg->addr = iphdr.p_vaddr; 411 seg->off = iphdr.p_offset; 412 seg->fsz = iphdr.p_filesz; 413 seg->msz = iphdr.p_memsz; 414 seg->type = iphdr.p_type; 415 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list); 416 } 417 } 418 419 void 420 copy_phdr(struct elfcopy *ecp) 421 { 422 struct segment *seg; 423 struct section *s; 424 GElf_Phdr iphdr, ophdr; 425 int i; 426 427 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 428 if (seg->type == PT_PHDR) { 429 if (!TAILQ_EMPTY(&ecp->v_sec)) { 430 s = TAILQ_FIRST(&ecp->v_sec); 431 if (s->pseudo) 432 seg->addr = s->lma + 433 gelf_fsize(ecp->eout, ELF_T_EHDR, 434 1, EV_CURRENT); 435 } 436 seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR, 437 ecp->ophnum, EV_CURRENT); 438 continue; 439 } 440 441 seg->fsz = seg->msz = 0; 442 for (i = 0; i < seg->nsec; i++) { 443 s = seg->v_sec[i]; 444 seg->msz = s->vma + s->sz - seg->addr; 445 if (s->type != SHT_NOBITS) 446 seg->fsz = seg->msz; 447 } 448 } 449 450 /* 451 * Allocate space for program headers, note that libelf keep 452 * track of the number in internal variable, and a call to 453 * elf_update is needed to update e_phnum of ehdr. 454 */ 455 if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL) 456 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s", 457 elf_errmsg(-1)); 458 459 /* 460 * This elf_update() call is to update the e_phnum field in 461 * ehdr. It's necessary because later we will call gelf_getphdr(), 462 * which does sanity check by comparing ndx argument with e_phnum. 463 */ 464 if (elf_update(ecp->eout, ELF_C_NULL) < 0) 465 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1)); 466 467 /* 468 * iphnum == ophnum, since we don't remove program headers even if 469 * they no longer contain sections. 470 */ 471 i = 0; 472 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 473 if (i >= ecp->iphnum) 474 break; 475 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr) 476 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 477 elf_errmsg(-1)); 478 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr) 479 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 480 elf_errmsg(-1)); 481 482 ophdr.p_type = iphdr.p_type; 483 ophdr.p_vaddr = seg->addr; 484 ophdr.p_paddr = seg->addr; 485 ophdr.p_flags = iphdr.p_flags; 486 ophdr.p_align = iphdr.p_align; 487 ophdr.p_offset = seg->off; 488 ophdr.p_filesz = seg->fsz; 489 ophdr.p_memsz = seg->msz; 490 if (!gelf_update_phdr(ecp->eout, i, &ophdr)) 491 err(EXIT_FAILURE, "gelf_update_phdr failed :%s", 492 elf_errmsg(-1)); 493 494 i++; 495 } 496 } 497