1 /* $NetBSD: mdreloc.c,v 1.41 2018/04/03 21:10:27 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.41 2018/04/03 21:10:27 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; 117 118 119 case R_TYPE(IRELATIVE): 120 /* IFUNC relocations are handled in _rtld_call_ifunc */ 121 if (obj->ifunc_remaining_nonplt == 0) { 122 obj->ifunc_remaining_nonplt = 123 obj->rellim - rel; 124 } 125 /* FALL-THROUGH */ 126 127 case R_TYPE(RELATIVE): 128 *where += (Elf_Addr)obj->relocbase; 129 rdbg(("RELATIVE in %s --> %p", obj->path, 130 (void *)*where)); 131 break; 132 133 case R_TYPE(COPY): 134 /* 135 * These are deferred until all other relocations have 136 * been done. All we do here is make sure that the 137 * COPY relocation is not in a shared library. They 138 * are allowed only in executable files. 139 */ 140 if (obj->isdynamic) { 141 _rtld_error( 142 "%s: Unexpected R_COPY relocation in shared library", 143 obj->path); 144 return -1; 145 } 146 rdbg(("COPY (avoid in main)")); 147 break; 148 149 case R_TYPE(TLS_TPOFF): 150 if (!defobj->tls_done && 151 _rtld_tls_offset_allocate(obj)) 152 return -1; 153 154 *where += (Elf_Addr)(def->st_value - defobj->tlsoffset); 155 156 rdbg(("TLS_TPOFF %s in %s --> %p", 157 obj->strtab + obj->symtab[symnum].st_name, 158 obj->path, (void *)*where)); 159 break; 160 161 case R_TYPE(TLS_TPOFF32): 162 if (!defobj->tls_done && 163 _rtld_tls_offset_allocate(obj)) 164 return -1; 165 166 *where += (Elf_Addr)(defobj->tlsoffset - def->st_value); 167 rdbg(("TLS_TPOFF32 %s in %s --> %p", 168 obj->strtab + obj->symtab[symnum].st_name, 169 obj->path, (void *)*where)); 170 break; 171 172 case R_TYPE(TLS_DTPMOD32): 173 *where = (Elf_Addr)(defobj->tlsindex); 174 175 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 176 obj->strtab + obj->symtab[symnum].st_name, 177 obj->path, (void *)*where)); 178 break; 179 180 case R_TYPE(TLS_DTPOFF32): 181 *where = (Elf_Addr)(def->st_value); 182 183 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 184 obj->strtab + obj->symtab[symnum].st_name, 185 obj->path, (void *)*where)); 186 187 break; 188 189 default: 190 rdbg(("sym = %lu, type = %lu, offset = %p, " 191 "contents = %p, symbol = %s", 192 (u_long)ELF_R_SYM(rel->r_info), 193 (u_long)ELF_R_TYPE(rel->r_info), 194 (void *)rel->r_offset, (void *)*where, 195 obj->strtab + obj->symtab[symnum].st_name)); 196 _rtld_error("%s: Unsupported relocation type %ld " 197 "in non-PLT relocations", 198 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 199 return -1; 200 } 201 } 202 return 0; 203 } 204 205 int 206 _rtld_relocate_plt_lazy(Obj_Entry *obj) 207 { 208 const Elf_Rel *rel; 209 210 for (rel = obj->pltrellim; rel-- > obj->pltrel; ) { 211 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 212 213 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT) || 214 ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)); 215 216 if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)) 217 obj->ifunc_remaining = obj->pltrellim - rel; 218 219 /* Just relocate the GOT slots pointing into the PLT */ 220 *where += (Elf_Addr)obj->relocbase; 221 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 222 } 223 224 return 0; 225 } 226 227 static inline int 228 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 229 Elf_Addr *tp) 230 { 231 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 232 Elf_Addr target; 233 const Elf_Sym *def; 234 const Obj_Entry *defobj; 235 unsigned long info = rel->r_info; 236 237 if (ELF_R_TYPE(info) == R_TYPE(IRELATIVE)) 238 return 0; 239 240 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 241 242 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 243 if (__predict_false(def == NULL)) 244 return -1; 245 if (__predict_false(def == &_rtld_sym_zero)) 246 return 0; 247 248 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 249 if (tp == NULL) 250 return 0; 251 target = _rtld_resolve_ifunc(defobj, def); 252 } else { 253 target = (Elf_Addr)(defobj->relocbase + def->st_value); 254 } 255 256 rdbg(("bind now/fixup in %s --> old=%p new=%p", 257 defobj->strtab + def->st_name, (void *)*where, 258 (void *)target)); 259 if (*where != target) 260 *where = target; 261 if (tp) 262 *tp = target; 263 return 0; 264 } 265 266 caddr_t 267 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 268 { 269 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel 270 + reloff); 271 Elf_Addr new_value; 272 int err; 273 274 new_value = 0; /* XXX gcc */ 275 276 _rtld_shared_enter(); 277 err = _rtld_relocate_plt_object(obj, rel, &new_value); 278 if (err) 279 _rtld_die(); 280 _rtld_shared_exit(); 281 282 return (caddr_t)new_value; 283 } 284 285 int 286 _rtld_relocate_plt_objects(const Obj_Entry *obj) 287 { 288 const Elf_Rel *rel; 289 int err = 0; 290 291 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 292 err = _rtld_relocate_plt_object(obj, rel, NULL); 293 if (err) 294 break; 295 } 296 return err; 297 } 298 299 /* 300 * i386 specific GNU variant of __tls_get_addr using register based 301 * argument passing. 302 */ 303 #define DTV_MAX_INDEX(dtv) ((size_t)((dtv)[-1])) 304 305 __dso_public __attribute__((__regparm__(1))) void * 306 ___tls_get_addr(void *arg_) 307 { 308 size_t *arg = (size_t *)arg_; 309 void **dtv; 310 struct tls_tcb *tcb = __lwp_getprivate_fast(); 311 size_t idx = arg[0], offset = arg[1]; 312 313 dtv = tcb->tcb_dtv; 314 315 if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL)) 316 return (uint8_t *)dtv[idx] + offset; 317 318 return _rtld_tls_get_addr(tcb, idx, offset); 319 } 320