1 /* $NetBSD: mdreloc.c,v 1.44 2018/04/03 21:10:27 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.44 2018/04/03 21:10:27 joerg Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <string.h> 10 11 #include "debug.h" 12 #include "rtld.h" 13 14 void _rtld_bind_start(void); 15 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 16 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 17 18 void 19 _rtld_setup_pltgot(const Obj_Entry *obj) 20 { 21 obj->pltgot[1] = (Elf_Addr) obj; 22 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 23 } 24 25 void 26 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 27 { 28 const Elf_Rel *rel = 0, *rellim; 29 Elf_Addr relsz = 0; 30 Elf_Addr *where; 31 32 for (; dynp->d_tag != DT_NULL; dynp++) { 33 switch (dynp->d_tag) { 34 case DT_REL: 35 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 36 break; 37 case DT_RELSZ: 38 relsz = dynp->d_un.d_val; 39 break; 40 } 41 } 42 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 43 for (; rel < rellim; rel++) { 44 where = (Elf_Addr *)(relocbase + rel->r_offset); 45 *where += (Elf_Addr)relocbase; 46 } 47 } 48 49 /* 50 * It is possible for the compiler to emit relocations for unaligned data. 51 * We handle this situation with these inlines. 52 */ 53 #define RELOC_ALIGNED_P(x) \ 54 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 55 56 static inline Elf_Addr 57 load_ptr(void *where) 58 { 59 Elf_Addr res; 60 61 memcpy(&res, where, sizeof(res)); 62 63 return (res); 64 } 65 66 static inline void 67 store_ptr(void *where, Elf_Addr val) 68 { 69 70 memcpy(where, &val, sizeof(val)); 71 } 72 73 int 74 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 75 { 76 const Elf_Rel *rel; 77 const Elf_Sym *def = NULL; 78 const Obj_Entry *defobj = NULL; 79 unsigned long last_symnum = ULONG_MAX; 80 81 for (rel = obj->rel; rel < obj->rellim; rel++) { 82 Elf_Addr *where; 83 Elf_Addr tmp; 84 unsigned long symnum; 85 86 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 87 88 switch (ELF_R_TYPE(rel->r_info)) { 89 case R_TYPE(PC24): /* word32 S - P + A */ 90 case R_TYPE(ABS32): /* word32 B + S + A */ 91 case R_TYPE(GLOB_DAT): /* word32 B + S */ 92 case R_TYPE(TLS_DTPOFF32): 93 case R_TYPE(TLS_DTPMOD32): 94 case R_TYPE(TLS_TPOFF32): 95 symnum = ELF_R_SYM(rel->r_info); 96 if (last_symnum != symnum) { 97 last_symnum = symnum; 98 def = _rtld_find_symdef(symnum, obj, &defobj, 99 false); 100 if (def == NULL) 101 return -1; 102 } 103 break; 104 105 default: 106 break; 107 } 108 109 switch (ELF_R_TYPE(rel->r_info)) { 110 case R_TYPE(NONE): 111 break; 112 113 #if 1 /* XXX should not occur */ 114 case R_TYPE(PC24): { /* word32 S - P + A */ 115 Elf32_Sword addend; 116 117 /* 118 * Extract addend and sign-extend if needed. 119 */ 120 addend = *where; 121 if (addend & 0x00800000) 122 addend |= 0xff000000; 123 tmp = (Elf_Addr)obj->relocbase + def->st_value 124 - (Elf_Addr)where + (addend << 2); 125 if ((tmp & 0xfe000000) != 0xfe000000 && 126 (tmp & 0xfe000000) != 0) { 127 _rtld_error( 128 "%s: R_ARM_PC24 relocation @ %p to %s failed " 129 "(displacement %ld (%#lx) out of range)", 130 obj->path, where, 131 obj->strtab + obj->symtab[ 132 ELF_R_SYM(rel->r_info)].st_name, 133 (long) tmp, (long) tmp); 134 return -1; 135 } 136 tmp >>= 2; 137 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 138 rdbg(("PC24 %s in %s --> %p @ %p in %s", 139 obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] 140 .st_name, obj->path, (void *)*where, where, 141 defobj->path)); 142 break; 143 } 144 #endif 145 146 case R_TYPE(ABS32): /* word32 B + S + A */ 147 case R_TYPE(GLOB_DAT): /* word32 B + S */ 148 if (__predict_true(RELOC_ALIGNED_P(where))) { 149 tmp = *where + (Elf_Addr)defobj->relocbase + 150 def->st_value; 151 /* Set the Thumb bit, if needed. */ 152 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 153 tmp |= 1; 154 *where = tmp; 155 } else { 156 tmp = load_ptr(where) + 157 (Elf_Addr)defobj->relocbase + 158 def->st_value; 159 /* Set the Thumb bit, if needed. */ 160 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 161 tmp |= 1; 162 store_ptr(where, tmp); 163 } 164 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", 165 obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] 166 .st_name, obj->path, (void *)tmp, where, 167 defobj->path)); 168 break; 169 170 case R_TYPE(IRELATIVE): 171 /* IFUNC relocations are handled in _rtld_call_ifunc */ 172 if (obj->ifunc_remaining_nonplt == 0) 173 obj->ifunc_remaining_nonplt = obj->rellim - rel; 174 /* FALL-THROUGH */ 175 176 case R_TYPE(RELATIVE): /* word32 B + A */ 177 if (__predict_true(RELOC_ALIGNED_P(where))) { 178 tmp = *where + (Elf_Addr)obj->relocbase; 179 *where = tmp; 180 } else { 181 tmp = load_ptr(where) + 182 (Elf_Addr)obj->relocbase; 183 store_ptr(where, tmp); 184 } 185 rdbg(("RELATIVE in %s --> %p", obj->path, 186 (void *)tmp)); 187 break; 188 189 case R_TYPE(COPY): 190 /* 191 * These are deferred until all other relocations have 192 * been done. All we do here is make sure that the 193 * COPY relocation is not in a shared library. They 194 * are allowed only in executable files. 195 */ 196 if (obj->isdynamic) { 197 _rtld_error( 198 "%s: Unexpected R_COPY relocation in shared library", 199 obj->path); 200 return -1; 201 } 202 rdbg(("COPY (avoid in main)")); 203 break; 204 205 case R_TYPE(TLS_DTPOFF32): 206 tmp = (Elf_Addr)(def->st_value); 207 if (__predict_true(RELOC_ALIGNED_P(where))) 208 *where = tmp; 209 else 210 store_ptr(where, tmp); 211 212 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 213 obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] 214 .st_name, obj->path, (void *)tmp)); 215 216 break; 217 case R_TYPE(TLS_DTPMOD32): 218 tmp = (Elf_Addr)(defobj->tlsindex); 219 if (__predict_true(RELOC_ALIGNED_P(where))) 220 *where = tmp; 221 else 222 store_ptr(where, tmp); 223 224 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 225 obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] 226 .st_name, obj->path, (void *)tmp)); 227 228 break; 229 230 case R_TYPE(TLS_TPOFF32): 231 if (!defobj->tls_done && 232 _rtld_tls_offset_allocate(obj)) 233 return -1; 234 235 tmp = (Elf_Addr)def->st_value + defobj->tlsoffset + 236 sizeof(struct tls_tcb); 237 if (__predict_true(RELOC_ALIGNED_P(where))) 238 *where = tmp; 239 else 240 store_ptr(where, tmp); 241 rdbg(("TLS_TPOFF32 %s in %s --> %p", 242 obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] 243 .st_name, obj->path, (void *)tmp)); 244 break; 245 246 default: 247 rdbg(("sym = %lu, type = %lu, offset = %p, " 248 "contents = %p", 249 (u_long)ELF_R_SYM(rel->r_info), 250 (u_long)ELF_R_TYPE(rel->r_info), 251 (void *)rel->r_offset, (void *)load_ptr(where))); 252 _rtld_error("%s: Unsupported relocation type %ld " 253 "in non-PLT relocations", 254 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 255 return -1; 256 } 257 } 258 return 0; 259 } 260 261 int 262 _rtld_relocate_plt_lazy(Obj_Entry *obj) 263 { 264 const Elf_Rel *rel; 265 266 for (rel = obj->pltrellim; rel-- > obj->pltrel; ) { 267 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 268 269 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT) || 270 ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)); 271 272 if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)) 273 obj->ifunc_remaining = obj->pltrellim - rel; 274 275 /* Just relocate the GOT slots pointing into the PLT */ 276 *where += (Elf_Addr)obj->relocbase; 277 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 278 } 279 280 return 0; 281 } 282 283 static int 284 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 285 Elf_Addr *tp) 286 { 287 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 288 Elf_Addr new_value; 289 const Elf_Sym *def; 290 const Obj_Entry *defobj; 291 unsigned long info = rel->r_info; 292 293 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 294 295 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 296 if (__predict_false(def == NULL)) 297 return -1; 298 if (__predict_false(def == &_rtld_sym_zero)) 299 return 0; 300 301 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 302 if (tp == NULL) 303 return 0; 304 new_value = _rtld_resolve_ifunc(defobj, def); 305 } else { 306 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 307 } 308 /* Set the Thumb bit, if needed. */ 309 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 310 new_value |= 1; 311 rdbg(("bind now/fixup in %s --> old=%p new=%p", 312 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 313 if (*where != new_value) 314 *where = new_value; 315 if (tp) 316 *tp = new_value; 317 318 return 0; 319 } 320 321 caddr_t 322 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 323 { 324 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff); 325 Elf_Addr new_value = 0; /* XXX gcc */ 326 int err; 327 328 _rtld_shared_enter(); 329 err = _rtld_relocate_plt_object(obj, rel, &new_value); 330 if (err) 331 _rtld_die(); 332 _rtld_shared_exit(); 333 334 return (caddr_t)new_value; 335 } 336 int 337 _rtld_relocate_plt_objects(const Obj_Entry *obj) 338 { 339 const Elf_Rel *rel; 340 int err = 0; 341 342 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 343 err = _rtld_relocate_plt_object(obj, rel, NULL); 344 if (err) 345 break; 346 } 347 348 return err; 349 } 350