headers.c revision 1.4.4.1
1 /* $NetBSD: headers.c,v 1.4.4.1 1999/12/27 18:30:14 wrstuden 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_Word relsz = 0, relasz = 0; 68 Elf_Word pltrelsz = 0, pltrelasz = 0; 69 70 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) { 71 switch (dynp->d_tag) { 72 73 case DT_REL: 74 obj->rel = (const Elf_Rel *) 75 (obj->relocbase + dynp->d_un.d_ptr); 76 break; 77 78 case DT_RELSZ: 79 relsz = dynp->d_un.d_val; 80 break; 81 82 case DT_RELENT: 83 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 84 break; 85 86 case DT_JMPREL: 87 if (plttype == DT_REL) { 88 obj->pltrel = (const Elf_Rel *) 89 (obj->relocbase + dynp->d_un.d_ptr); 90 } else { 91 obj->pltrela = (const Elf_RelA *) 92 (obj->relocbase + dynp->d_un.d_ptr); 93 } 94 break; 95 96 case DT_PLTRELSZ: 97 if (plttype == DT_REL) { 98 pltrelsz = dynp->d_un.d_val; 99 } else { 100 pltrelasz = dynp->d_un.d_val; 101 } 102 break; 103 104 case DT_RELA: 105 obj->rela = (const Elf_RelA *) 106 (obj->relocbase + dynp->d_un.d_ptr); 107 break; 108 109 case DT_RELASZ: 110 relasz = dynp->d_un.d_val; 111 break; 112 113 case DT_RELAENT: 114 assert(dynp->d_un.d_val == sizeof(Elf_RelA)); 115 break; 116 117 case DT_PLTREL: 118 plttype = dynp->d_un.d_val; 119 assert(plttype == DT_REL || 120 plttype == DT_RELA); 121 if (plttype == DT_RELA) { 122 obj->pltrela = (const Elf_RelA *) obj->pltrel; 123 obj->pltrel = NULL; 124 pltrelasz = pltrelsz; 125 pltrelsz = 0; 126 } 127 break; 128 129 case DT_SYMTAB: 130 obj->symtab = (const Elf_Sym *) 131 (obj->relocbase + dynp->d_un.d_ptr); 132 break; 133 134 case DT_SYMENT: 135 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 136 break; 137 138 case DT_STRTAB: 139 obj->strtab = (const char *) 140 (obj->relocbase + dynp->d_un.d_ptr); 141 break; 142 143 case DT_STRSZ: 144 obj->strsize = dynp->d_un.d_val; 145 break; 146 147 case DT_HASH: 148 { 149 const Elf_Word *hashtab = (const Elf_Word *) 150 (obj->relocbase + dynp->d_un.d_ptr); 151 152 obj->nbuckets = hashtab[0]; 153 obj->nchains = hashtab[1]; 154 obj->buckets = hashtab + 2; 155 obj->chains = obj->buckets + obj->nbuckets; 156 } 157 break; 158 159 case DT_NEEDED: 160 assert(!obj->rtld); 161 { 162 Needed_Entry *nep = NEW(Needed_Entry); 163 164 nep->name = dynp->d_un.d_val; 165 nep->obj = NULL; 166 nep->next = NULL; 167 168 *needed_tail = nep; 169 needed_tail = &nep->next; 170 } 171 break; 172 173 case DT_PLTGOT: 174 obj->pltgot = (Elf_Addr *) 175 (obj->relocbase + dynp->d_un.d_ptr); 176 break; 177 178 case DT_TEXTREL: 179 obj->textrel = true; 180 break; 181 182 case DT_SYMBOLIC: 183 obj->symbolic = true; 184 break; 185 186 case DT_RPATH: 187 /* 188 * We have to wait until later to process this, because 189 * we might not have gotten the address of the string 190 * table yet. 191 */ 192 dyn_rpath = dynp; 193 break; 194 195 case DT_SONAME: 196 /* Not used by the dynamic linker. */ 197 break; 198 199 case DT_INIT: 200 obj->init = (void (*) __P((void))) 201 (obj->relocbase + dynp->d_un.d_ptr); 202 break; 203 204 case DT_FINI: 205 obj->fini = (void (*) __P((void))) 206 (obj->relocbase + 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 obj->pltrellim = (const Elf_Rel *)((caddr_t)obj->pltrel + pltrelsz); 241 obj->pltrelalim = (const Elf_RelA *)((caddr_t)obj->pltrela + pltrelasz); 242 243 if (dyn_rpath != NULL) { 244 _rtld_add_paths(&obj->rpaths, obj->strtab + 245 dyn_rpath->d_un.d_val, true); 246 } 247 } 248 249 /* 250 * Process a shared object's program header. This is used only for the 251 * main program, when the kernel has already loaded the main program 252 * into memory before calling the dynamic linker. It creates and 253 * returns an Obj_Entry structure. 254 */ 255 Obj_Entry * 256 _rtld_digest_phdr(phdr, phnum, entry) 257 const Elf_Phdr *phdr; 258 int phnum; 259 caddr_t entry; 260 { 261 Obj_Entry *obj; 262 const Elf_Phdr *phlimit = phdr + phnum; 263 const Elf_Phdr *ph; 264 int nsegs = 0; 265 266 obj = _rtld_obj_new(); 267 for (ph = phdr; ph < phlimit; ++ph) { 268 switch (ph->p_type) { 269 270 case PT_PHDR: 271 assert((const Elf_Phdr *) ph->p_vaddr == phdr); 272 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 273 obj->phsize = ph->p_memsz; 274 break; 275 276 case PT_INTERP: 277 obj->interp = (const char *) ph->p_vaddr; 278 break; 279 280 case PT_LOAD: 281 assert(nsegs < 2); 282 if (nsegs == 0) { /* First load segment */ 283 obj->vaddrbase = round_down(ph->p_vaddr); 284 obj->mapbase = (caddr_t) obj->vaddrbase; 285 obj->relocbase = obj->mapbase - obj->vaddrbase; 286 obj->textsize = round_up(ph->p_vaddr + 287 ph->p_memsz) - obj->vaddrbase; 288 } else { /* Last load segment */ 289 obj->mapsize = round_up(ph->p_vaddr + 290 ph->p_memsz) - obj->vaddrbase; 291 } 292 ++nsegs; 293 break; 294 295 case PT_DYNAMIC: 296 obj->dynamic = (Elf_Dyn *) ph->p_vaddr; 297 break; 298 } 299 } 300 assert(nsegs == 2); 301 302 obj->entry = entry; 303 return obj; 304 } 305
Indexes created Wed Oct 15 16:09:53 GMT 2025