1 /* $NetBSD: mdreloc.c,v 1.38 2010/08/06 16:33:19 joerg Exp $ */ 2 3 /* 4 * Copyright (c) 2001 Wasabi Systems, Inc. 5 * All rights reserved. 6 * 7 * Written by Frank van der Linden for Wasabi Systems, Inc. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed for the NetBSD Project by 20 * Wasabi Systems, Inc. 21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse 22 * or promote products derived from this software without specific prior 23 * written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC 29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 * POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 /* 39 * Copyright 1996 John D. Polstra. 40 * Copyright 1996 Matt Thomas <matt@3am-software.com> 41 * All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by John Polstra. 54 * 4. The name of the author may not be used to endorse or promote products 55 * derived from this software without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 58 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 59 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 60 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 61 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 62 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 63 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 64 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 65 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 66 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 67 */ 68 69 #include <sys/cdefs.h> 70 #ifndef lint 71 __RCSID("$NetBSD: mdreloc.c,v 1.38 2010/08/06 16:33:19 joerg Exp $"); 72 #endif /* not lint */ 73 74 #include <sys/types.h> 75 #include <sys/mman.h> 76 #include <errno.h> 77 #include <fcntl.h> 78 #include <stdarg.h> 79 #include <stdio.h> 80 #include <stdlib.h> 81 #include <string.h> 82 #include <unistd.h> 83 #include <elf.h> 84 85 #include "debug.h" 86 #include "rtld.h" 87 88 void _rtld_bind_start(void); 89 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 90 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 91 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 92 const Elf_Rela *, Elf_Addr *); 93 94 void 95 _rtld_setup_pltgot(const Obj_Entry *obj) 96 { 97 obj->pltgot[1] = (Elf_Addr) obj; 98 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 99 } 100 101 void 102 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 103 { 104 const Elf_Rela *rela = 0, *relalim; 105 Elf_Addr relasz = 0; 106 Elf_Addr *where; 107 108 for (; dynp->d_tag != DT_NULL; dynp++) { 109 switch (dynp->d_tag) { 110 case DT_RELA: 111 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 112 break; 113 case DT_RELASZ: 114 relasz = dynp->d_un.d_val; 115 break; 116 } 117 } 118 /* 119 * Assume only 64-bit relocations here, which should always 120 * be true for the dynamic linker. 121 */ 122 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 123 for (; rela < relalim; rela++) { 124 where = (Elf_Addr *)(relocbase + rela->r_offset); 125 *where = (Elf_Addr)(relocbase + rela->r_addend); 126 } 127 } 128 129 int 130 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 131 { 132 const Elf_Rela *rela; 133 const Elf_Sym *def = NULL; 134 const Obj_Entry *defobj =NULL; 135 136 for (rela = obj->rela; rela < obj->relalim; rela++) { 137 Elf64_Addr *where64; 138 Elf32_Addr *where32; 139 Elf64_Addr tmp64; 140 Elf32_Addr tmp32; 141 unsigned long symnum; 142 143 where64 = (Elf64_Addr *)(obj->relocbase + rela->r_offset); 144 where32 = (Elf32_Addr *)where64; 145 symnum = ELF_R_SYM(rela->r_info); 146 147 switch (ELF_R_TYPE(rela->r_info)) { 148 case R_TYPE(NONE): 149 break; 150 151 case R_TYPE(32): /* word32 S + A, truncate */ 152 case R_TYPE(32S): /* word32 S + A, signed truncate */ 153 case R_TYPE(GOT32): /* word32 G + A (XXX can we see these?) */ 154 def = _rtld_find_symdef(symnum, obj, &defobj, false); 155 if (def == NULL) 156 return -1; 157 tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + 158 def->st_value + rela->r_addend); 159 160 if (*where32 != tmp32) 161 *where32 = tmp32; 162 rdbg(("32/32S %s in %s --> %p in %s", 163 obj->strtab + obj->symtab[symnum].st_name, 164 obj->path, (void *)(unsigned long)*where32, 165 defobj->path)); 166 break; 167 case R_TYPE(64): /* word64 S + A */ 168 def = _rtld_find_symdef(symnum, obj, &defobj, false); 169 if (def == NULL) 170 return -1; 171 tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value + 172 rela->r_addend); 173 174 if (*where64 != tmp64) 175 *where64 = tmp64; 176 rdbg(("64 %s in %s --> %p in %s", 177 obj->strtab + obj->symtab[symnum].st_name, 178 obj->path, (void *)*where64, defobj->path)); 179 break; 180 case R_TYPE(PC32): /* word32 S + A - P */ 181 def = _rtld_find_symdef(symnum, obj, &defobj, false); 182 if (def == NULL) 183 return -1; 184 tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + 185 def->st_value + rela->r_addend - 186 (Elf64_Addr)where64); 187 if (*where32 != tmp32) 188 *where32 = tmp32; 189 rdbg(("PC32 %s in %s --> %p in %s", 190 obj->strtab + obj->symtab[symnum].st_name, 191 obj->path, (void *)(unsigned long)*where32, 192 defobj->path)); 193 break; 194 case R_TYPE(GLOB_DAT): /* word64 S */ 195 def = _rtld_find_symdef(symnum, obj, &defobj, false); 196 if (def == NULL) 197 return -1; 198 tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value); 199 200 if (*where64 != tmp64) 201 *where64 = tmp64; 202 rdbg(("64 %s in %s --> %p in %s", 203 obj->strtab + obj->symtab[symnum].st_name, 204 obj->path, (void *)*where64, defobj->path)); 205 break; 206 case R_TYPE(RELATIVE): /* word64 B + A */ 207 tmp64 = (Elf64_Addr)(obj->relocbase + rela->r_addend); 208 if (*where64 != tmp64) 209 *where64 = tmp64; 210 rdbg(("RELATIVE in %s --> %p", obj->path, 211 (void *)*where64)); 212 break; 213 214 case R_TYPE(COPY): 215 rdbg(("COPY")); 216 break; 217 218 default: 219 rdbg(("sym = %lu, type = %lu, offset = %p, " 220 "addend = %p, contents = %p, symbol = %s", 221 symnum, (u_long)ELF_R_TYPE(rela->r_info), 222 (void *)rela->r_offset, (void *)rela->r_addend, 223 (void *)*where64, 224 obj->strtab + obj->symtab[symnum].st_name)); 225 _rtld_error("%s: Unsupported relocation type %ld " 226 "in non-PLT relocations", 227 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 228 return -1; 229 } 230 } 231 return 0; 232 } 233 234 int 235 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 236 { 237 const Elf_Rela *rela; 238 239 if (!obj->relocbase) 240 return 0; 241 242 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { 243 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 244 245 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)); 246 247 /* Just relocate the GOT slots pointing into the PLT */ 248 *where += (Elf_Addr)obj->relocbase; 249 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 250 } 251 252 return 0; 253 } 254 255 static inline int 256 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 257 { 258 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 259 Elf_Addr new_value; 260 const Elf_Sym *def; 261 const Obj_Entry *defobj; 262 unsigned long info = rela->r_info; 263 264 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 265 266 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 267 if (__predict_false(def == NULL)) 268 return -1; 269 if (__predict_false(def == &_rtld_sym_zero)) 270 return 0; 271 272 new_value = (Elf_Addr)(defobj->relocbase + def->st_value + 273 rela->r_addend); 274 rdbg(("bind now/fixup in %s --> old=%p new=%p", 275 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 276 if (*where != new_value) 277 *where = new_value; 278 279 if (tp) 280 *tp = new_value - rela->r_addend; 281 282 return 0; 283 } 284 285 caddr_t 286 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 287 { 288 const Elf_Rela *rela = obj->pltrela + reloff; 289 Elf_Addr new_value; 290 int error; 291 292 new_value = 0; /* XXX GCC4 */ 293 294 error = _rtld_relocate_plt_object(obj, rela, &new_value); 295 if (error) 296 _rtld_die(); 297 298 return (caddr_t)new_value; 299 } 300 301 int 302 _rtld_relocate_plt_objects(const Obj_Entry *obj) 303 { 304 const Elf_Rela *rela; 305 306 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) 307 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 308 return -1; 309 310 return 0; 311 } 312