headers.c revision 1.11
1 /* $NetBSD: headers.c,v 1.11 2002/09/05 16:58:16 mycroft Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Dynamic linker for ELF. 36 * 37 * John Polstra <jdp (at) polstra.com>. 38 */ 39 40 #include <err.h> 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <stdarg.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include <sys/types.h> 49 #include <sys/mman.h> 50 #include <dirent.h> 51 52 #include "debug.h" 53 #include "rtld.h" 54 55 /* 56 * Process a shared object's DYNAMIC section, and save the important 57 * information in its Obj_Entry structure. 58 */ 59 void 60 _rtld_digest_dynamic(obj) 61 Obj_Entry *obj; 62 { 63 Elf_Dyn *dynp; 64 Needed_Entry **needed_tail = &obj->needed; 65 const Elf_Dyn *dyn_rpath = NULL; 66 Elf_Sword plttype = DT_REL; 67 Elf_Addr relsz = 0, relasz = 0; 68 Elf_Addr pltrelsz = 0; 69 Elf_Addr init = 0, fini = 0; 70 71 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) { 72 switch (dynp->d_tag) { 73 74 case DT_REL: 75 obj->rel = (const Elf_Rel *) 76 (obj->relocbase + dynp->d_un.d_ptr); 77 break; 78 79 case DT_RELSZ: 80 relsz = dynp->d_un.d_val; 81 break; 82 83 case DT_RELENT: 84 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 85 break; 86 87 case DT_JMPREL: 88 if (plttype == DT_REL) { 89 obj->pltrel = (const Elf_Rel *) 90 (obj->relocbase + dynp->d_un.d_ptr); 91 } else { 92 obj->pltrela = (const Elf_Rela *) 93 (obj->relocbase + dynp->d_un.d_ptr); 94 } 95 break; 96 97 case DT_PLTRELSZ: 98 pltrelsz = dynp->d_un.d_val; 99 break; 100 101 case DT_RELA: 102 obj->rela = (const Elf_Rela *) 103 (obj->relocbase + dynp->d_un.d_ptr); 104 break; 105 106 case DT_RELASZ: 107 relasz = dynp->d_un.d_val; 108 break; 109 110 case DT_RELAENT: 111 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 112 break; 113 114 case DT_PLTREL: 115 plttype = dynp->d_un.d_val; 116 assert(plttype == DT_REL || 117 plttype == DT_RELA); 118 #if !defined(__sparc__) && !defined(__archv9__) && !defined(__sparc_v9__) 119 /* 120 * sparc v9 has both DT_PLTREL and DT_JMPREL. 121 * But they point to different things. 122 * We want the DT_JMPREL which points to our jump table. 123 */ 124 if (plttype == DT_RELA) { 125 obj->pltrela = (const Elf_Rela *) obj->pltrel; 126 obj->pltrel = NULL; 127 } 128 #endif 129 break; 130 131 case DT_SYMTAB: 132 obj->symtab = (const Elf_Sym *) 133 (obj->relocbase + dynp->d_un.d_ptr); 134 break; 135 136 case DT_SYMENT: 137 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 138 break; 139 140 case DT_STRTAB: 141 obj->strtab = (const char *) 142 (obj->relocbase + dynp->d_un.d_ptr); 143 break; 144 145 case DT_STRSZ: 146 obj->strsize = dynp->d_un.d_val; 147 break; 148 149 case DT_HASH: 150 { 151 const Elf_Word *hashtab = (const Elf_Word *) 152 (obj->relocbase + dynp->d_un.d_ptr); 153 154 obj->nbuckets = hashtab[0]; 155 obj->nchains = hashtab[1]; 156 obj->buckets = hashtab + 2; 157 obj->chains = obj->buckets + obj->nbuckets; 158 } 159 break; 160 161 case DT_NEEDED: 162 assert(!obj->rtld); 163 { 164 Needed_Entry *nep = NEW(Needed_Entry); 165 166 nep->name = dynp->d_un.d_val; 167 nep->obj = NULL; 168 nep->next = NULL; 169 170 *needed_tail = nep; 171 needed_tail = &nep->next; 172 } 173 break; 174 175 case DT_PLTGOT: 176 obj->pltgot = (Elf_Addr *) 177 (obj->relocbase + dynp->d_un.d_ptr); 178 break; 179 180 case DT_TEXTREL: 181 obj->textrel = true; 182 break; 183 184 case DT_SYMBOLIC: 185 obj->symbolic = true; 186 break; 187 188 case DT_RPATH: 189 /* 190 * We have to wait until later to process this, because 191 * we might not have gotten the address of the string 192 * table yet. 193 */ 194 dyn_rpath = dynp; 195 break; 196 197 case DT_SONAME: 198 /* Not used by the dynamic linker. */ 199 break; 200 201 case DT_INIT: 202 init = dynp->d_un.d_ptr; 203 break; 204 205 case DT_FINI: 206 fini = dynp->d_un.d_ptr; 207 break; 208 209 case DT_DEBUG: 210 #ifdef RTLD_LOADER 211 dynp->d_un.d_ptr = (Elf_Addr)&_rtld_debug; 212 #endif 213 break; 214 215 #if defined(__mips__) 216 case DT_MIPS_LOCAL_GOTNO: 217 obj->local_gotno = dynp->d_un.d_val; 218 break; 219 220 case DT_MIPS_SYMTABNO: 221 obj->symtabno = dynp->d_un.d_val; 222 break; 223 224 case DT_MIPS_GOTSYM: 225 obj->gotsym = dynp->d_un.d_val; 226 break; 227 228 case DT_MIPS_RLD_MAP: 229 #ifdef RTLD_LOADER 230 *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) 231 &_rtld_debug; 232 #endif 233 break; 234 #endif 235 } 236 } 237 238 obj->rellim = (const Elf_Rel *)((caddr_t)obj->rel + relsz); 239 obj->relalim = (const Elf_Rela *)((caddr_t)obj->rela + relasz); 240 if (plttype == DT_REL) { 241 /* On PPC and SPARC, at least, REL(A)SZ may include PLTREL. */ 242 if (obj->rellim && obj->pltrel && obj->rellim > obj->pltrel) 243 obj->rellim = obj->pltrel; 244 obj->pltrellim = (const Elf_Rel *)((caddr_t)obj->pltrel + pltrelsz); 245 obj->pltrelalim = 0; 246 } else { 247 /* On PPC and SPARC, at least, REL(A)SZ may include PLTREL. */ 248 if (obj->relalim && obj->pltrela && obj->relalim > obj->pltrela) 249 obj->relalim = obj->pltrela; 250 obj->pltrellim = 0; 251 obj->pltrelalim = (const Elf_Rela *)((caddr_t)obj->pltrela + pltrelsz); 252 } 253 254 #if defined(RTLD_LOADER) && defined(__HAVE_FUNCTION_DESCRIPTORS) 255 if (init != 0) 256 obj->init = (void (*) __P((void))) 257 _rtld_function_descriptor_alloc(obj, NULL, init); 258 if (fini != 0) 259 obj->fini = (void (*) __P((void))) 260 _rtld_function_descriptor_alloc(obj, NULL, fini); 261 #else 262 if (init != 0) 263 obj->init = (void (*) __P((void))) 264 (obj->relocbase + init); 265 if (fini != 0) 266 obj->fini = (void (*) __P((void))) 267 (obj->relocbase + fini); 268 #endif 269 270 if (dyn_rpath != NULL) { 271 _rtld_add_paths(&obj->rpaths, obj->strtab + 272 dyn_rpath->d_un.d_val, true); 273 } 274 } 275 276 /* 277 * Process a shared object's program header. This is used only for the 278 * main program, when the kernel has already loaded the main program 279 * into memory before calling the dynamic linker. It creates and 280 * returns an Obj_Entry structure. 281 */ 282 Obj_Entry * 283 _rtld_digest_phdr(phdr, phnum, entry) 284 const Elf_Phdr *phdr; 285 int phnum; 286 caddr_t entry; 287 { 288 Obj_Entry *obj; 289 const Elf_Phdr *phlimit = phdr + phnum; 290 const Elf_Phdr *ph; 291 int nsegs = 0; 292 293 obj = _rtld_obj_new(); 294 for (ph = phdr; ph < phlimit; ++ph) { 295 switch (ph->p_type) { 296 297 case PT_PHDR: 298 assert((const Elf_Phdr *) ph->p_vaddr == phdr); 299 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 300 obj->phsize = ph->p_memsz; 301 break; 302 303 case PT_INTERP: 304 obj->interp = (const char *) ph->p_vaddr; 305 break; 306 307 case PT_LOAD: 308 assert(nsegs < 2); 309 if (nsegs == 0) { /* First load segment */ 310 obj->vaddrbase = round_down(ph->p_vaddr); 311 obj->mapbase = (caddr_t) obj->vaddrbase; 312 obj->relocbase = obj->mapbase - obj->vaddrbase; 313 obj->textsize = round_up(ph->p_vaddr + 314 ph->p_memsz) - obj->vaddrbase; 315 } else { /* Last load segment */ 316 obj->mapsize = round_up(ph->p_vaddr + 317 ph->p_memsz) - obj->vaddrbase; 318 } 319 ++nsegs; 320 break; 321 322 case PT_DYNAMIC: 323 obj->dynamic = (Elf_Dyn *) ph->p_vaddr; 324 break; 325 } 326 } 327 assert(nsegs == 2); 328 329 obj->entry = entry; 330 return obj; 331 } 332
Indexes created Fri Oct 17 23:09:53 GMT 2025