1 /* $OpenBSD: resolve.c,v 1.17 2003/02/02 16:57:58 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB 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 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed under OpenBSD by 17 * Per Fogelstrom, Opsycon AB, Sweden. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 22 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 25 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 */ 34 35 #define _DYN_LOADER 36 37 #include <sys/types.h> 38 39 #include <nlist.h> 40 #include <link.h> 41 #include "syscall.h" 42 #include "archdep.h" 43 #include "resolve.h" 44 45 elf_object_t *_dl_objects; 46 elf_object_t *_dl_last_object; 47 48 /* 49 * Initialize and add a new dynamic object to the object list. 50 * Perform necessary relocations of pointers. 51 */ 52 elf_object_t * 53 _dl_add_object(const char *objname, Elf_Dyn *dynp, const u_long *dl_data, 54 const int objtype, const long laddr, const long loff) 55 { 56 elf_object_t *object; 57 #if 0 58 _dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n", 59 objname, dynp, dl_data, objtype, laddr, loff); 60 #endif 61 62 object = _dl_malloc(sizeof(elf_object_t)); 63 64 object->next = NULL; 65 if (_dl_objects == 0) { /* First object ? */ 66 _dl_last_object = _dl_objects = object; 67 } else { 68 _dl_last_object->next = object; 69 object->prev = _dl_last_object; 70 _dl_last_object = object; 71 } 72 73 object->load_dyn = dynp; 74 while (dynp->d_tag != DT_NULL) { 75 if (dynp->d_tag < DT_NUM) 76 object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val; 77 else if (dynp->d_tag >= DT_LOPROC && 78 dynp->d_tag < DT_LOPROC + DT_NUM) 79 object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = 80 dynp->d_un.d_val; 81 if (dynp->d_tag == DT_TEXTREL) 82 object->dyn.textrel = 1; 83 if (dynp->d_tag == DT_SYMBOLIC) 84 object->dyn.symbolic = 1; 85 if (dynp->d_tag == DT_BIND_NOW) 86 object->dyn.bind_now = 1; 87 dynp++; 88 } 89 90 /* 91 * Now relocate all pointer to dynamic info, but only 92 * the ones which have pointer values. 93 */ 94 if (object->Dyn.info[DT_PLTGOT]) 95 object->Dyn.info[DT_PLTGOT] += loff; 96 if (object->Dyn.info[DT_HASH]) 97 object->Dyn.info[DT_HASH] += loff; 98 if (object->Dyn.info[DT_STRTAB]) 99 object->Dyn.info[DT_STRTAB] += loff; 100 if (object->Dyn.info[DT_SYMTAB]) 101 object->Dyn.info[DT_SYMTAB] += loff; 102 if (object->Dyn.info[DT_RELA]) 103 object->Dyn.info[DT_RELA] += loff; 104 if (object->Dyn.info[DT_SONAME]) 105 object->Dyn.info[DT_SONAME] += loff; 106 if (object->Dyn.info[DT_RPATH]) 107 object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB]; 108 if (object->Dyn.info[DT_REL]) 109 object->Dyn.info[DT_REL] += loff; 110 if (object->Dyn.info[DT_INIT]) 111 object->Dyn.info[DT_INIT] += loff; 112 if (object->Dyn.info[DT_FINI]) 113 object->Dyn.info[DT_FINI] += loff; 114 if (object->Dyn.info[DT_JMPREL]) 115 object->Dyn.info[DT_JMPREL] += loff; 116 117 if (object->Dyn.info[DT_HASH] != 0) { 118 Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH]; 119 120 object->nbuckets = hashtab[0]; 121 object->nchains = hashtab[1]; 122 object->buckets = hashtab + 2; 123 object->chains = object->buckets + object->nbuckets; 124 } 125 126 if (dl_data) { 127 object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr]; 128 object->phdrc = dl_data[AUX_phnum]; 129 } 130 object->obj_type = objtype; 131 object->load_addr = laddr; 132 object->load_offs = loff; 133 object->load_name = _dl_strdup(objname); 134 object->refcount = 1; 135 object->first_child = NULL; 136 object->last_child = NULL; 137 return(object); 138 } 139 140 void 141 _dl_remove_object(elf_object_t *object) 142 { 143 elf_object_t *depobj; 144 145 object->prev->next = object->next; 146 if (object->next) 147 object->next->prev = object->prev; 148 149 if (_dl_last_object == object) 150 _dl_last_object = object->prev; 151 152 if (object->load_name) 153 _dl_free(object->load_name); 154 155 while ((depobj = object->dep_next)) { 156 object->dep_next = object->dep_next->dep_next; 157 _dl_free(depobj); 158 } 159 _dl_free(object); 160 } 161 162 163 elf_object_t * 164 _dl_lookup_object(const char *name) 165 { 166 elf_object_t *object; 167 168 object = _dl_objects; 169 while (object) { 170 if (_dl_strcmp(name, object->load_name) == 0) 171 return(object); 172 object = object->next; 173 } 174 return(0); 175 } 176 177 178 Elf_Addr 179 _dl_find_symbol(const char *name, elf_object_t *startlook, 180 const Elf_Sym **ref, int flags, int req_size, const char *module_name) 181 { 182 const Elf_Sym *weak_sym = NULL; 183 const char *weak_symn = NULL; /* remove warning */ 184 Elf_Addr weak_offs = 0; 185 unsigned long h = 0; 186 const char *p = name; 187 elf_object_t *object, *weak_object = NULL; 188 189 while (*p) { 190 unsigned long g; 191 h = (h << 4) + *p++; 192 if ((g = h & 0xf0000000)) 193 h ^= g >> 24; 194 h &= ~g; 195 } 196 197 for (object = startlook; object; 198 object = ((flags & SYM_SEARCH_SELF) ? 0 : object->next)) { 199 const Elf_Sym *symt = object->dyn.symtab; 200 const char *strt = object->dyn.strtab; 201 long si; 202 const char *symn; 203 204 for (si = object->buckets[h % object->nbuckets]; 205 si != STN_UNDEF; si = object->chains[si]) { 206 const Elf_Sym *sym = symt + si; 207 208 if (sym->st_value == 0) 209 continue; 210 211 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 212 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 213 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 214 continue; 215 216 symn = strt + sym->st_name; 217 if (sym != *ref && _dl_strcmp(symn, name)) 218 continue; 219 220 /* allow this symbol if we are referring to a function 221 * which has a value, even if section is UNDEF. 222 * this allows &func to refer to PLT as per the 223 * ELF spec. st_value is checked above. 224 * if flags has SYM_PLT set, we must have actual 225 * symbol, so this symbol is skipped. 226 */ 227 if (sym->st_shndx == SHN_UNDEF) { 228 if ((flags & SYM_PLT) || sym->st_value == 0 || 229 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 230 continue; 231 } 232 233 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 234 *ref = sym; 235 if (req_size != sym->st_size && 236 req_size != 0 && 237 (ELF_ST_TYPE(sym->st_info) != STT_FUNC)) { 238 _dl_printf("%s: %s : WARNING: " 239 "symbol(%s) size mismatch ", 240 _dl_progname, object->load_name, 241 symn); 242 _dl_printf("relink your program\n"); 243 } 244 return(object->load_offs); 245 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 246 if (!weak_sym) { 247 weak_sym = sym; 248 weak_symn = symn; 249 weak_offs = object->load_offs; 250 weak_object = object; 251 } 252 } 253 } 254 } 255 if (flags & SYM_WARNNOTFOUND && weak_sym == NULL) { 256 _dl_printf("%s:%s: undefined symbol '%s'\n", 257 _dl_progname, module_name, name); 258 } 259 *ref = weak_sym; 260 if (weak_sym != NULL && req_size != weak_sym->st_size && 261 req_size != 0 && (ELF_ST_TYPE(weak_sym->st_info) != STT_FUNC)) { 262 _dl_printf("%s:%s: %s : WARNING: " 263 "symbol(%s) size mismatch ", 264 _dl_progname, module_name, weak_object->load_name, 265 weak_symn); 266 _dl_printf("relink your program\n"); 267 } 268 return (weak_offs); 269 } 270