1 /* $OpenBSD: resolve.c,v 1.18 2003/06/09 16:10:03 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 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 #define _DYN_LOADER 30 31 #include <sys/types.h> 32 33 #include <nlist.h> 34 #include <link.h> 35 #include "syscall.h" 36 #include "archdep.h" 37 #include "resolve.h" 38 39 elf_object_t *_dl_objects; 40 elf_object_t *_dl_last_object; 41 42 /* 43 * Initialize and add a new dynamic object to the object list. 44 * Perform necessary relocations of pointers. 45 */ 46 elf_object_t * 47 _dl_add_object(const char *objname, Elf_Dyn *dynp, const u_long *dl_data, 48 const int objtype, const long laddr, const long loff) 49 { 50 elf_object_t *object; 51 #if 0 52 _dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n", 53 objname, dynp, dl_data, objtype, laddr, loff); 54 #endif 55 56 object = _dl_malloc(sizeof(elf_object_t)); 57 58 object->next = NULL; 59 if (_dl_objects == 0) { /* First object ? */ 60 _dl_last_object = _dl_objects = object; 61 } else { 62 _dl_last_object->next = object; 63 object->prev = _dl_last_object; 64 _dl_last_object = object; 65 } 66 67 object->load_dyn = dynp; 68 while (dynp->d_tag != DT_NULL) { 69 if (dynp->d_tag < DT_NUM) 70 object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val; 71 else if (dynp->d_tag >= DT_LOPROC && 72 dynp->d_tag < DT_LOPROC + DT_NUM) 73 object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = 74 dynp->d_un.d_val; 75 if (dynp->d_tag == DT_TEXTREL) 76 object->dyn.textrel = 1; 77 if (dynp->d_tag == DT_SYMBOLIC) 78 object->dyn.symbolic = 1; 79 if (dynp->d_tag == DT_BIND_NOW) 80 object->dyn.bind_now = 1; 81 dynp++; 82 } 83 84 /* 85 * Now relocate all pointer to dynamic info, but only 86 * the ones which have pointer values. 87 */ 88 if (object->Dyn.info[DT_PLTGOT]) 89 object->Dyn.info[DT_PLTGOT] += loff; 90 if (object->Dyn.info[DT_HASH]) 91 object->Dyn.info[DT_HASH] += loff; 92 if (object->Dyn.info[DT_STRTAB]) 93 object->Dyn.info[DT_STRTAB] += loff; 94 if (object->Dyn.info[DT_SYMTAB]) 95 object->Dyn.info[DT_SYMTAB] += loff; 96 if (object->Dyn.info[DT_RELA]) 97 object->Dyn.info[DT_RELA] += loff; 98 if (object->Dyn.info[DT_SONAME]) 99 object->Dyn.info[DT_SONAME] += loff; 100 if (object->Dyn.info[DT_RPATH]) 101 object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB]; 102 if (object->Dyn.info[DT_REL]) 103 object->Dyn.info[DT_REL] += loff; 104 if (object->Dyn.info[DT_INIT]) 105 object->Dyn.info[DT_INIT] += loff; 106 if (object->Dyn.info[DT_FINI]) 107 object->Dyn.info[DT_FINI] += loff; 108 if (object->Dyn.info[DT_JMPREL]) 109 object->Dyn.info[DT_JMPREL] += loff; 110 111 if (object->Dyn.info[DT_HASH] != 0) { 112 Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH]; 113 114 object->nbuckets = hashtab[0]; 115 object->nchains = hashtab[1]; 116 object->buckets = hashtab + 2; 117 object->chains = object->buckets + object->nbuckets; 118 } 119 120 if (dl_data) { 121 object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr]; 122 object->phdrc = dl_data[AUX_phnum]; 123 } 124 object->obj_type = objtype; 125 object->load_addr = laddr; 126 object->load_offs = loff; 127 object->load_name = _dl_strdup(objname); 128 object->refcount = 1; 129 object->first_child = NULL; 130 object->last_child = NULL; 131 return(object); 132 } 133 134 void 135 _dl_remove_object(elf_object_t *object) 136 { 137 elf_object_t *depobj; 138 139 object->prev->next = object->next; 140 if (object->next) 141 object->next->prev = object->prev; 142 143 if (_dl_last_object == object) 144 _dl_last_object = object->prev; 145 146 if (object->load_name) 147 _dl_free(object->load_name); 148 149 while ((depobj = object->dep_next)) { 150 object->dep_next = object->dep_next->dep_next; 151 _dl_free(depobj); 152 } 153 _dl_free(object); 154 } 155 156 157 elf_object_t * 158 _dl_lookup_object(const char *name) 159 { 160 elf_object_t *object; 161 162 object = _dl_objects; 163 while (object) { 164 if (_dl_strcmp(name, object->load_name) == 0) 165 return(object); 166 object = object->next; 167 } 168 return(0); 169 } 170 171 172 Elf_Addr 173 _dl_find_symbol(const char *name, elf_object_t *startlook, 174 const Elf_Sym **ref, int flags, int req_size, const char *module_name) 175 { 176 const Elf_Sym *weak_sym = NULL; 177 const char *weak_symn = NULL; /* remove warning */ 178 Elf_Addr weak_offs = 0; 179 unsigned long h = 0; 180 const char *p = name; 181 elf_object_t *object, *weak_object = NULL; 182 183 while (*p) { 184 unsigned long g; 185 h = (h << 4) + *p++; 186 if ((g = h & 0xf0000000)) 187 h ^= g >> 24; 188 h &= ~g; 189 } 190 191 for (object = startlook; object; 192 object = ((flags & SYM_SEARCH_SELF) ? 0 : object->next)) { 193 const Elf_Sym *symt = object->dyn.symtab; 194 const char *strt = object->dyn.strtab; 195 long si; 196 const char *symn; 197 198 for (si = object->buckets[h % object->nbuckets]; 199 si != STN_UNDEF; si = object->chains[si]) { 200 const Elf_Sym *sym = symt + si; 201 202 if (sym->st_value == 0) 203 continue; 204 205 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 206 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 207 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 208 continue; 209 210 symn = strt + sym->st_name; 211 if (sym != *ref && _dl_strcmp(symn, name)) 212 continue; 213 214 /* allow this symbol if we are referring to a function 215 * which has a value, even if section is UNDEF. 216 * this allows &func to refer to PLT as per the 217 * ELF spec. st_value is checked above. 218 * if flags has SYM_PLT set, we must have actual 219 * symbol, so this symbol is skipped. 220 */ 221 if (sym->st_shndx == SHN_UNDEF) { 222 if ((flags & SYM_PLT) || sym->st_value == 0 || 223 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 224 continue; 225 } 226 227 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 228 *ref = sym; 229 if (req_size != sym->st_size && 230 req_size != 0 && 231 (ELF_ST_TYPE(sym->st_info) != STT_FUNC)) { 232 _dl_printf("%s: %s : WARNING: " 233 "symbol(%s) size mismatch ", 234 _dl_progname, object->load_name, 235 symn); 236 _dl_printf("relink your program\n"); 237 } 238 return(object->load_offs); 239 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 240 if (!weak_sym) { 241 weak_sym = sym; 242 weak_symn = symn; 243 weak_offs = object->load_offs; 244 weak_object = object; 245 } 246 } 247 } 248 } 249 if (flags & SYM_WARNNOTFOUND && weak_sym == NULL) { 250 _dl_printf("%s:%s: undefined symbol '%s'\n", 251 _dl_progname, module_name, name); 252 } 253 *ref = weak_sym; 254 if (weak_sym != NULL && req_size != weak_sym->st_size && 255 req_size != 0 && (ELF_ST_TYPE(weak_sym->st_info) != STT_FUNC)) { 256 _dl_printf("%s:%s: %s : WARNING: " 257 "symbol(%s) size mismatch ", 258 _dl_progname, module_name, weak_object->load_name, 259 weak_symn); 260 _dl_printf("relink your program\n"); 261 } 262 return (weak_offs); 263 } 264