1 /* $NetBSD: mdreloc.c,v 1.40 2017/11/06 21:16:04 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.40 2017/11/06 21:16:04 joerg Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <sys/ucontext.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 if (rel == 0 || relsz == 0) 43 return; 44 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 45 for (; rel < rellim; rel++) { 46 where = (Elf_Addr *)(relocbase + rel->r_offset); 47 *where += (Elf_Addr)relocbase; 48 } 49 } 50 51 int 52 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 53 { 54 const Elf_Rel *rel; 55 Elf_Addr target = 0; 56 const Elf_Sym *def = NULL; 57 const Obj_Entry *defobj = NULL; 58 unsigned long last_symnum = ULONG_MAX; 59 60 for (rel = obj->rel; rel < obj->rellim; rel++) { 61 Elf_Addr *where; 62 Elf_Addr tmp; 63 unsigned long symnum; 64 65 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 66 67 switch (ELF_R_TYPE(rel->r_info)) { 68 case R_TYPE(PC32): 69 case R_TYPE(GOT32): 70 case R_TYPE(32): 71 case R_TYPE(GLOB_DAT): 72 case R_TYPE(TLS_TPOFF): 73 case R_TYPE(TLS_TPOFF32): 74 case R_TYPE(TLS_DTPMOD32): 75 case R_TYPE(TLS_DTPOFF32): 76 symnum = ELF_R_SYM(rel->r_info); 77 if (symnum != last_symnum) { 78 last_symnum = symnum; 79 def = _rtld_find_symdef(symnum, obj, &defobj, 80 false); 81 if (def == NULL) 82 return -1; 83 } 84 break; 85 default: 86 break; 87 } 88 89 90 switch (ELF_R_TYPE(rel->r_info)) { 91 case R_TYPE(NONE): 92 break; 93 94 #if 1 /* XXX should not occur */ 95 case R_TYPE(PC32): 96 target = (Elf_Addr)(defobj->relocbase + def->st_value); 97 98 *where += target - (Elf_Addr)where; 99 rdbg(("PC32 %s in %s --> %p in %s", 100 obj->strtab + obj->symtab[symnum].st_name, 101 obj->path, (void *)*where, defobj->path)); 102 break; 103 104 case R_TYPE(GOT32): 105 #endif 106 case R_TYPE(32): 107 case R_TYPE(GLOB_DAT): 108 target = (Elf_Addr)(defobj->relocbase + def->st_value); 109 110 tmp = target + *where; 111 if (*where != tmp) 112 *where = tmp; 113 rdbg(("32/GLOB_DAT %s in %s --> %p in %s", 114 obj->strtab + obj->symtab[symnum].st_name, 115 obj->path, (void *)*where, defobj->path)); 116 break; 117 118 case R_TYPE(RELATIVE): 119 *where += (Elf_Addr)obj->relocbase; 120 rdbg(("RELATIVE in %s --> %p", obj->path, 121 (void *)*where)); 122 break; 123 124 case R_TYPE(COPY): 125 /* 126 * These are deferred until all other relocations have 127 * been done. All we do here is make sure that the 128 * COPY relocation is not in a shared library. They 129 * are allowed only in executable files. 130 */ 131 if (obj->isdynamic) { 132 _rtld_error( 133 "%s: Unexpected R_COPY relocation in shared library", 134 obj->path); 135 return -1; 136 } 137 rdbg(("COPY (avoid in main)")); 138 break; 139 140 case R_TYPE(TLS_TPOFF): 141 if (!defobj->tls_done && 142 _rtld_tls_offset_allocate(obj)) 143 return -1; 144 145 *where += (Elf_Addr)(def->st_value - defobj->tlsoffset); 146 147 rdbg(("TLS_TPOFF %s in %s --> %p", 148 obj->strtab + obj->symtab[symnum].st_name, 149 obj->path, (void *)*where)); 150 break; 151 152 case R_TYPE(TLS_TPOFF32): 153 if (!defobj->tls_done && 154 _rtld_tls_offset_allocate(obj)) 155 return -1; 156 157 *where += (Elf_Addr)(defobj->tlsoffset - def->st_value); 158 rdbg(("TLS_TPOFF32 %s in %s --> %p", 159 obj->strtab + obj->symtab[symnum].st_name, 160 obj->path, (void *)*where)); 161 break; 162 163 case R_TYPE(TLS_DTPMOD32): 164 *where = (Elf_Addr)(defobj->tlsindex); 165 166 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 167 obj->strtab + obj->symtab[symnum].st_name, 168 obj->path, (void *)*where)); 169 break; 170 171 case R_TYPE(TLS_DTPOFF32): 172 *where = (Elf_Addr)(def->st_value); 173 174 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 175 obj->strtab + obj->symtab[symnum].st_name, 176 obj->path, (void *)*where)); 177 178 break; 179 180 default: 181 rdbg(("sym = %lu, type = %lu, offset = %p, " 182 "contents = %p, symbol = %s", 183 (u_long)ELF_R_SYM(rel->r_info), 184 (u_long)ELF_R_TYPE(rel->r_info), 185 (void *)rel->r_offset, (void *)*where, 186 obj->strtab + obj->symtab[symnum].st_name)); 187 _rtld_error("%s: Unsupported relocation type %ld " 188 "in non-PLT relocations", 189 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 190 return -1; 191 } 192 } 193 return 0; 194 } 195 196 int 197 _rtld_relocate_plt_lazy(Obj_Entry *obj) 198 { 199 const Elf_Rel *rel; 200 201 for (rel = obj->pltrellim; rel-- > obj->pltrel; ) { 202 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 203 204 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT) || 205 ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)); 206 207 if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)) 208 obj->ifunc_remaining = obj->pltrellim - rel; 209 210 /* Just relocate the GOT slots pointing into the PLT */ 211 *where += (Elf_Addr)obj->relocbase; 212 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 213 } 214 215 return 0; 216 } 217 218 void 219 _rtld_call_ifunc(Obj_Entry *obj, sigset_t *mask, u_int cur_objgen) 220 { 221 const Elf_Rel *rel; 222 Elf_Addr *where, target; 223 224 while (obj->ifunc_remaining > 0 && _rtld_objgen == cur_objgen) { 225 rel = obj->pltrellim - obj->ifunc_remaining; 226 --obj->ifunc_remaining; 227 if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)) { 228 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 229 _rtld_exclusive_exit(mask); 230 target = _rtld_resolve_ifunc2(obj, *where); 231 _rtld_exclusive_enter(mask); 232 if (*where != target) 233 *where = target; 234 } 235 } 236 } 237 238 static inline int 239 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 240 Elf_Addr *tp) 241 { 242 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 243 Elf_Addr target; 244 const Elf_Sym *def; 245 const Obj_Entry *defobj; 246 unsigned long info = rel->r_info; 247 248 if (ELF_R_TYPE(info) == R_TYPE(IRELATIVE)) 249 return 0; 250 251 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 252 253 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 254 if (__predict_false(def == NULL)) 255 return -1; 256 if (__predict_false(def == &_rtld_sym_zero)) 257 return 0; 258 259 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 260 if (tp == NULL) 261 return 0; 262 target = _rtld_resolve_ifunc(defobj, def); 263 } else { 264 target = (Elf_Addr)(defobj->relocbase + def->st_value); 265 } 266 267 rdbg(("bind now/fixup in %s --> old=%p new=%p", 268 defobj->strtab + def->st_name, (void *)*where, 269 (void *)target)); 270 if (*where != target) 271 *where = target; 272 if (tp) 273 *tp = target; 274 return 0; 275 } 276 277 caddr_t 278 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 279 { 280 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel 281 + reloff); 282 Elf_Addr new_value; 283 int err; 284 285 new_value = 0; /* XXX gcc */ 286 287 _rtld_shared_enter(); 288 err = _rtld_relocate_plt_object(obj, rel, &new_value); 289 if (err) 290 _rtld_die(); 291 _rtld_shared_exit(); 292 293 return (caddr_t)new_value; 294 } 295 296 int 297 _rtld_relocate_plt_objects(const Obj_Entry *obj) 298 { 299 const Elf_Rel *rel; 300 int err = 0; 301 302 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 303 err = _rtld_relocate_plt_object(obj, rel, NULL); 304 if (err) 305 break; 306 } 307 return err; 308 } 309 310 /* 311 * i386 specific GNU variant of __tls_get_addr using register based 312 * argument passing. 313 */ 314 #define DTV_MAX_INDEX(dtv) ((size_t)((dtv)[-1])) 315 316 __dso_public __attribute__((__regparm__(1))) void * 317 ___tls_get_addr(void *arg_) 318 { 319 size_t *arg = (size_t *)arg_; 320 void **dtv; 321 struct tls_tcb *tcb = __lwp_getprivate_fast(); 322 size_t idx = arg[0], offset = arg[1]; 323 324 dtv = tcb->tcb_dtv; 325 326 if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL)) 327 return (uint8_t *)dtv[idx] + offset; 328 329 return _rtld_tls_get_addr(tcb, idx, offset); 330 } 331