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/queue.h> 28 #include <err.h> 29 #include <gelf.h> 30 #include <stdint.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <string.h> 34 35 #include "elfcopy.h" 36 37 ELFTC_VCSID("$Id: segments.c 3269 2015-12-11 18:38:43Z kaiwang27 $"); 38 39 static void insert_to_inseg_list(struct segment *seg, struct section *sec); 40 41 /* 42 * elfcopy's segment handling is relatively simpler and less powerful than 43 * libbfd. Program headers are modified or copied from input to output objects, 44 * but never re-generated. As a result, if the input object has incorrect 45 * program headers, the output object's program headers will remain incorrect 46 * or become even worse. 47 */ 48 49 /* 50 * Check whether a section is "loadable". If so, add it to the 51 * corresponding segment list(s) and return 1. 52 */ 53 int 54 add_to_inseg_list(struct elfcopy *ecp, struct section *s) 55 { 56 struct segment *seg; 57 int loadable; 58 59 if (ecp->ophnum == 0) 60 return (0); 61 62 /* 63 * Segment is a different view of an ELF object. One segment can 64 * contain one or more sections, and one section can be included 65 * in one or more segments, or not included in any segment at all. 66 * We call those sections which can be found in one or more segments 67 * "loadable" sections, and call the rest "unloadable" sections. 68 * We keep track of "loadable" sections in their containing 69 * segment(s)' v_sec queue. These information are later used to 70 * recalculate the extents of segments, when sections are removed, 71 * for example. 72 */ 73 loadable = 0; 74 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 75 if (s->off < seg->off || (s->vma < seg->addr && !s->pseudo)) 76 continue; 77 if (s->off + s->sz > seg->off + seg->fsz && 78 s->type != SHT_NOBITS) 79 continue; 80 if (s->vma + s->sz > seg->addr + seg->msz) 81 continue; 82 83 insert_to_inseg_list(seg, s); 84 if (seg->type == PT_LOAD) 85 s->seg = seg; 86 else if (seg->type == PT_TLS) 87 s->seg_tls = seg; 88 s->lma = seg->addr + (s->off - seg->off); 89 loadable = 1; 90 } 91 92 return (loadable); 93 } 94 95 void 96 adjust_addr(struct elfcopy *ecp) 97 { 98 struct section *s, *s0; 99 struct segment *seg; 100 struct sec_action *sac; 101 uint64_t dl, lma, start, end; 102 int found, i; 103 104 /* 105 * Apply VMA and global LMA changes in the first iteration. 106 */ 107 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 108 109 /* Only adjust loadable section's address. */ 110 if (!s->loadable || s->seg == NULL) 111 continue; 112 113 /* Apply global LMA adjustment. */ 114 if (ecp->change_addr != 0) 115 s->lma += ecp->change_addr; 116 117 if (!s->pseudo) { 118 /* Apply global VMA adjustment. */ 119 if (ecp->change_addr != 0) 120 s->vma += ecp->change_addr; 121 122 /* Apply section VMA adjustment. */ 123 sac = lookup_sec_act(ecp, s->name, 0); 124 if (sac == NULL) 125 continue; 126 if (sac->setvma) 127 s->vma = sac->vma; 128 if (sac->vma_adjust != 0) 129 s->vma += sac->vma_adjust; 130 } 131 } 132 133 /* 134 * Apply sections LMA change in the second iteration. 135 */ 136 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 137 138 /* Only adjust loadable section's LMA. */ 139 if (!s->loadable || s->seg == NULL) 140 continue; 141 142 /* 143 * Check if there is a LMA change request for this 144 * section. 145 */ 146 sac = lookup_sec_act(ecp, s->name, 0); 147 if (sac == NULL) 148 continue; 149 if (!sac->setlma && sac->lma_adjust == 0) 150 continue; 151 lma = s->lma; 152 if (sac->setlma) 153 lma = sac->lma; 154 if (sac->lma_adjust != 0) 155 lma += sac->lma_adjust; 156 if (lma == s->lma) 157 continue; 158 159 /* 160 * Check if the LMA change is viable. 161 * 162 * 1. Check if the new LMA is properly aligned accroding to 163 * section alignment. 164 * 165 * 2. Compute the new extent of segment that contains this 166 * section, make sure it doesn't overlap with other 167 * segments. 168 */ 169 #ifdef DEBUG 170 printf("LMA for section %s: %#jx\n", s->name, lma); 171 #endif 172 173 if (lma % s->align != 0) 174 errx(EXIT_FAILURE, "The load address %#jx for " 175 "section %s is not aligned to %ju", 176 (uintmax_t) lma, s->name, s->align); 177 178 if (lma < s->lma) { 179 /* Move section to lower address. */ 180 if (lma < s->lma - s->seg->addr) 181 errx(EXIT_FAILURE, "Not enough space to move " 182 "section %s load address to %#jx", s->name, 183 (uintmax_t) lma); 184 start = lma - (s->lma - s->seg->addr); 185 if (s == s->seg->v_sec[s->seg->nsec - 1]) 186 end = start + s->seg->msz; 187 else 188 end = s->seg->addr + s->seg->msz; 189 190 } else { 191 /* Move section to upper address. */ 192 if (s == s->seg->v_sec[0]) 193 start = lma; 194 else 195 start = s->seg->addr; 196 end = lma + (s->seg->addr + s->seg->msz - s->lma); 197 if (end < start) 198 errx(EXIT_FAILURE, "Not enough space to move " 199 "section %s load address to %#jx", s->name, 200 (uintmax_t) lma); 201 } 202 203 #ifdef DEBUG 204 printf("new extent for segment containing %s: (%#jx,%#jx)\n", 205 s->name, start, end); 206 #endif 207 208 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 209 if (seg == s->seg || seg->type != PT_LOAD) 210 continue; 211 if (start > seg->addr + seg->msz) 212 continue; 213 if (end < seg->addr) 214 continue; 215 errx(EXIT_FAILURE, "The extent of segment containing " 216 "section %s overlaps with segment(%#jx,%#jx)", 217 s->name, seg->addr, seg->addr + seg->msz); 218 } 219 220 /* 221 * Update section LMA and file offset. 222 */ 223 224 if (lma < s->lma) { 225 /* 226 * To move a section to lower load address, we decrease 227 * the load addresses of the section and all the 228 * sections that are before it, and we increase the 229 * file offsets of all the sections that are after it. 230 */ 231 dl = s->lma - lma; 232 for (i = 0; i < s->seg->nsec; i++) { 233 s0 = s->seg->v_sec[i]; 234 s0->lma -= dl; 235 #ifdef DEBUG 236 printf("section %s LMA set to %#jx\n", 237 s0->name, (uintmax_t) s0->lma); 238 #endif 239 if (s0 == s) 240 break; 241 } 242 for (i = i + 1; i < s->seg->nsec; i++) { 243 s0 = s->seg->v_sec[i]; 244 s0->off += dl; 245 #ifdef DEBUG 246 printf("section %s offset set to %#jx\n", 247 s0->name, (uintmax_t) s0->off); 248 #endif 249 } 250 } else { 251 /* 252 * To move a section to upper load address, we increase 253 * the load addresses of the section and all the 254 * sections that are after it, and we increase the 255 * their file offsets too unless the section in question 256 * is the first in its containing segment. 257 */ 258 dl = lma - s->lma; 259 for (i = 0; i < s->seg->nsec; i++) 260 if (s->seg->v_sec[i] == s) 261 break; 262 if (i >= s->seg->nsec) 263 errx(EXIT_FAILURE, "Internal: section `%s' not" 264 " found in its containing segement", 265 s->name); 266 for (; i < s->seg->nsec; i++) { 267 s0 = s->seg->v_sec[i]; 268 s0->lma += dl; 269 #ifdef DEBUG 270 printf("section %s LMA set to %#jx\n", 271 s0->name, (uintmax_t) s0->lma); 272 #endif 273 if (s != s->seg->v_sec[0]) { 274 s0->off += dl; 275 #ifdef DEBUG 276 printf("section %s offset set to %#jx\n", 277 s0->name, (uintmax_t) s0->off); 278 #endif 279 } 280 } 281 } 282 } 283 284 /* 285 * Apply load address padding. 286 */ 287 288 if (ecp->pad_to != 0) { 289 290 /* 291 * Find the section with highest load address. 292 */ 293 294 s = NULL; 295 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 296 if (seg->type != PT_LOAD) 297 continue; 298 for (i = seg->nsec - 1; i >= 0; i--) 299 if (seg->v_sec[i]->type != SHT_NOBITS) 300 break; 301 if (i < 0) 302 continue; 303 if (s == NULL) 304 s = seg->v_sec[i]; 305 else { 306 s0 = seg->v_sec[i]; 307 if (s0->lma > s->lma) 308 s = s0; 309 } 310 } 311 312 if (s == NULL) 313 goto issue_warn; 314 315 /* No need to pad if the pad_to address is lower. */ 316 if (ecp->pad_to <= s->lma + s->sz) 317 goto issue_warn; 318 319 s->pad_sz = ecp->pad_to - (s->lma + s->sz); 320 #ifdef DEBUG 321 printf("pad section %s load to address %#jx by %#jx\n", s->name, 322 (uintmax_t) ecp->pad_to, (uintmax_t) s->pad_sz); 323 #endif 324 } 325 326 issue_warn: 327 328 /* 329 * Issue a warning if there are VMA/LMA adjust requests for 330 * some nonexistent sections. 331 */ 332 if ((ecp->flags & NO_CHANGE_WARN) == 0) { 333 STAILQ_FOREACH(sac, &ecp->v_sac, sac_list) { 334 if (!sac->setvma && !sac->setlma && 335 !sac->vma_adjust && !sac->lma_adjust) 336 continue; 337 found = 0; 338 TAILQ_FOREACH(s, &ecp->v_sec, sec_list) { 339 if (s->pseudo || s->name == NULL) 340 continue; 341 if (!strcmp(s->name, sac->name)) { 342 found = 1; 343 break; 344 } 345 } 346 if (!found) 347 warnx("cannot find section `%s'", sac->name); 348 } 349 } 350 } 351 352 static void 353 insert_to_inseg_list(struct segment *seg, struct section *sec) 354 { 355 struct section *s; 356 int i; 357 358 seg->nsec++; 359 seg->v_sec = realloc(seg->v_sec, seg->nsec * sizeof(*seg->v_sec)); 360 if (seg->v_sec == NULL) 361 err(EXIT_FAILURE, "realloc failed"); 362 363 /* 364 * Sort the section in order of offset. 365 */ 366 367 for (i = seg->nsec - 1; i > 0; i--) { 368 s = seg->v_sec[i - 1]; 369 if (sec->off >= s->off) { 370 seg->v_sec[i] = sec; 371 break; 372 } else 373 seg->v_sec[i] = s; 374 } 375 if (i == 0) 376 seg->v_sec[0] = sec; 377 } 378 379 void 380 setup_phdr(struct elfcopy *ecp) 381 { 382 struct segment *seg; 383 GElf_Phdr iphdr; 384 size_t iphnum; 385 int i; 386 387 if (elf_getphnum(ecp->ein, &iphnum) == 0) 388 errx(EXIT_FAILURE, "elf_getphnum failed: %s", 389 elf_errmsg(-1)); 390 391 ecp->ophnum = ecp->iphnum = iphnum; 392 if (iphnum == 0) 393 return; 394 395 /* If --only-keep-debug is specified, discard all program headers. */ 396 if (ecp->strip == STRIP_NONDEBUG) { 397 ecp->ophnum = 0; 398 return; 399 } 400 401 for (i = 0; (size_t)i < iphnum; i++) { 402 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr) 403 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 404 elf_errmsg(-1)); 405 if ((seg = calloc(1, sizeof(*seg))) == NULL) 406 err(EXIT_FAILURE, "calloc failed"); 407 seg->addr = iphdr.p_vaddr; 408 seg->off = iphdr.p_offset; 409 seg->fsz = iphdr.p_filesz; 410 seg->msz = iphdr.p_memsz; 411 seg->type = iphdr.p_type; 412 STAILQ_INSERT_TAIL(&ecp->v_seg, seg, seg_list); 413 } 414 } 415 416 void 417 copy_phdr(struct elfcopy *ecp) 418 { 419 struct segment *seg; 420 struct section *s; 421 GElf_Phdr iphdr, ophdr; 422 int i; 423 424 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 425 if (seg->type == PT_PHDR) { 426 if (!TAILQ_EMPTY(&ecp->v_sec)) { 427 s = TAILQ_FIRST(&ecp->v_sec); 428 if (s->pseudo) 429 seg->addr = s->lma + 430 gelf_fsize(ecp->eout, ELF_T_EHDR, 431 1, EV_CURRENT); 432 } 433 seg->fsz = seg->msz = gelf_fsize(ecp->eout, ELF_T_PHDR, 434 ecp->ophnum, EV_CURRENT); 435 continue; 436 } 437 438 seg->fsz = seg->msz = 0; 439 for (i = 0; i < seg->nsec; i++) { 440 s = seg->v_sec[i]; 441 seg->msz = s->vma + s->sz - seg->addr; 442 if (s->type != SHT_NOBITS) 443 seg->fsz = s->off + s->sz - seg->off; 444 } 445 } 446 447 /* 448 * Allocate space for program headers, note that libelf keep 449 * track of the number in internal variable, and a call to 450 * elf_update is needed to update e_phnum of ehdr. 451 */ 452 if (gelf_newphdr(ecp->eout, ecp->ophnum) == NULL) 453 errx(EXIT_FAILURE, "gelf_newphdr() failed: %s", 454 elf_errmsg(-1)); 455 456 /* 457 * This elf_update() call is to update the e_phnum field in 458 * ehdr. It's necessary because later we will call gelf_getphdr(), 459 * which does sanity check by comparing ndx argument with e_phnum. 460 */ 461 if (elf_update(ecp->eout, ELF_C_NULL) < 0) 462 errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1)); 463 464 /* 465 * iphnum == ophnum, since we don't remove program headers even if 466 * they no longer contain sections. 467 */ 468 i = 0; 469 STAILQ_FOREACH(seg, &ecp->v_seg, seg_list) { 470 if (i >= ecp->iphnum) 471 break; 472 if (gelf_getphdr(ecp->ein, i, &iphdr) != &iphdr) 473 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 474 elf_errmsg(-1)); 475 if (gelf_getphdr(ecp->eout, i, &ophdr) != &ophdr) 476 errx(EXIT_FAILURE, "gelf_getphdr failed: %s", 477 elf_errmsg(-1)); 478 479 ophdr.p_type = iphdr.p_type; 480 ophdr.p_vaddr = seg->addr; 481 ophdr.p_paddr = seg->addr; 482 ophdr.p_flags = iphdr.p_flags; 483 ophdr.p_align = iphdr.p_align; 484 ophdr.p_offset = seg->off; 485 ophdr.p_filesz = seg->fsz; 486 ophdr.p_memsz = seg->msz; 487 if (!gelf_update_phdr(ecp->eout, i, &ophdr)) 488 err(EXIT_FAILURE, "gelf_update_phdr failed :%s", 489 elf_errmsg(-1)); 490 491 i++; 492 } 493 } 494