mdreloc.c revision 1.33.6.1
1 /* $NetBSD: mdreloc.c,v 1.33.6.1 2023/08/04 12:55:48 martin Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.33.6.1 2023/08/04 12:55:48 martin Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 10 #include "debug.h" 11 #include "rtld.h" 12 13 void _rtld_bind_start(void); 14 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 15 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 16 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 17 const Elf_Rela *, Elf_Addr *); 18 19 20 void 21 _rtld_setup_pltgot(const Obj_Entry *obj) 22 { 23 obj->pltgot[1] = (Elf_Addr) obj; 24 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 25 } 26 27 void 28 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 29 { 30 const Elf_Rela *rela = 0, *relalim; 31 Elf_Addr relasz = 0; 32 Elf_Addr *where; 33 34 for (; dynp->d_tag != DT_NULL; dynp++) { 35 switch (dynp->d_tag) { 36 case DT_RELA: 37 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 38 break; 39 case DT_RELASZ: 40 relasz = dynp->d_un.d_val; 41 break; 42 } 43 } 44 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 45 for (; rela < relalim; rela++) { 46 where = (Elf_Addr *)(relocbase + rela->r_offset); 47 *where += (Elf_Addr)relocbase; 48 } 49 } 50 51 int 52 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 53 { 54 const Elf_Rela *rela; 55 const Elf_Sym *def = NULL; 56 const Obj_Entry *defobj = NULL; 57 unsigned long last_symnum = ULONG_MAX; 58 59 for (rela = obj->rela; rela < obj->relalim; rela++) { 60 Elf_Addr *where; 61 Elf_Addr tmp; 62 unsigned long symnum; 63 64 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 65 66 switch (ELF_R_TYPE(rela->r_info)) { 67 case R_TYPE(PC32): 68 case R_TYPE(GOT32): 69 case R_TYPE(32): 70 case R_TYPE(GLOB_DAT): 71 case R_TYPE(TLS_DTPMOD32): 72 case R_TYPE(TLS_DTPREL32): 73 case R_TYPE(TLS_TPREL32): 74 symnum = ELF_R_SYM(rela->r_info); 75 if (last_symnum != symnum) { 76 last_symnum = symnum; 77 def = _rtld_find_symdef(symnum, obj, &defobj, 78 false); 79 if (def == NULL) 80 return -1; 81 } 82 break; 83 default: 84 break; 85 } 86 87 switch (ELF_R_TYPE(rela->r_info)) { 88 case R_TYPE(NONE): 89 break; 90 91 #if 1 /* XXX should not occur */ 92 case R_TYPE(PC32): 93 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 94 rela->r_addend) - (Elf_Addr)where; 95 if (*where != tmp) 96 *where = tmp; 97 rdbg(("PC32 %s in %s --> %p in %s", 98 obj->strtab + obj->symtab[symnum].st_name, 99 obj->path, (void *)*where, defobj->path)); 100 break; 101 102 case R_TYPE(GOT32): 103 #endif 104 case R_TYPE(32): 105 case R_TYPE(GLOB_DAT): 106 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 107 rela->r_addend); 108 if (*where != tmp) 109 *where = tmp; 110 rdbg(("32/GLOB_DAT %s in %s --> %p in %s", 111 obj->strtab + obj->symtab[symnum].st_name, 112 obj->path, (void *)*where, defobj->path)); 113 break; 114 115 case R_TYPE(RELATIVE): 116 *where += (Elf_Addr)obj->relocbase; 117 rdbg(("RELATIVE in %s --> %p", obj->path, 118 (void *)*where)); 119 break; 120 121 case R_TYPE(COPY): 122 /* 123 * These are deferred until all other relocations have 124 * been done. All we do here is make sure that the 125 * COPY relocation is not in a shared library. They 126 * are allowed only in executable files. 127 */ 128 if (obj->isdynamic) { 129 _rtld_error( 130 "%s: Unexpected R_COPY relocation in shared library", 131 obj->path); 132 return -1; 133 } 134 rdbg(("COPY (avoid in main)")); 135 break; 136 137 case R_TYPE(TLS_DTPMOD32): 138 *where = (Elf_Addr)defobj->tlsindex; 139 rdbg(("DTPMOD32 %s in %s --> %p in %s", 140 obj->strtab + obj->symtab[symnum].st_name, 141 obj->path, (void *)*where, defobj->path)); 142 break; 143 144 case R_TYPE(TLS_DTPREL32): 145 *where = (Elf_Addr)(def->st_value + rela->r_addend 146 - TLS_DTV_OFFSET); 147 rdbg(("DTPREL32 %s in %s --> %p in %s", 148 obj->strtab + obj->symtab[symnum].st_name, 149 obj->path, (void *)*where, defobj->path)); 150 break; 151 152 case R_TYPE(TLS_TPREL32): 153 if (!defobj->tls_static && 154 _rtld_tls_offset_allocate(__UNCONST(defobj))) 155 return -1; 156 157 *where = (Elf_Addr)(def->st_value + rela->r_addend 158 + defobj->tlsoffset - TLS_TP_OFFSET); 159 rdbg(("TPREL32 %s in %s --> %p in %s", 160 obj->strtab + obj->symtab[symnum].st_name, 161 obj->path, (void *)*where, defobj->path)); 162 break; 163 164 default: 165 rdbg(("sym = %lu, type = %lu, offset = %p, " 166 "addend = %p, contents = %p, symbol = %s", 167 (u_long)ELF_R_SYM(rela->r_info), 168 (u_long)ELF_R_TYPE(rela->r_info), 169 (void *)rela->r_offset, (void *)rela->r_addend, 170 (void *)*where, 171 obj->strtab + obj->symtab[symnum].st_name)); 172 _rtld_error("%s: Unsupported relocation type %ld " 173 "in non-PLT relocations", 174 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 175 return -1; 176 } 177 } 178 return 0; 179 } 180 181 int 182 _rtld_relocate_plt_lazy(Obj_Entry *obj) 183 { 184 const Elf_Rela *rela; 185 186 if (!obj->relocbase) 187 return 0; 188 189 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { 190 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 191 192 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 193 194 /* Just relocate the GOT slots pointing into the PLT */ 195 *where += (Elf_Addr)obj->relocbase; 196 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 197 } 198 199 return 0; 200 } 201 202 static inline int 203 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, 204 Elf_Addr *tp) 205 { 206 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 207 Elf_Addr new_value; 208 const Elf_Sym *def; 209 const Obj_Entry *defobj; 210 unsigned long info = rela->r_info; 211 212 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 213 214 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 215 if (__predict_false(def == NULL)) 216 return -1; 217 if (__predict_false(def == &_rtld_sym_zero)) 218 return 0; 219 220 assert(rela->r_addend == 0); 221 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 222 if (tp == NULL) 223 return 0; 224 new_value = _rtld_resolve_ifunc(defobj, def); 225 } else { 226 new_value = (Elf_Addr)(defobj->relocbase + def->st_value + 227 rela->r_addend); 228 } 229 rdbg(("bind now/fixup in %s --> old=%p new=%p", 230 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 231 if (*where != new_value) 232 *where = new_value; 233 234 if (tp) 235 *tp = new_value - rela->r_addend; 236 237 return 0; 238 } 239 240 caddr_t 241 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 242 { 243 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 244 Elf_Addr result; 245 int err; 246 247 result = 0; /* XXX gcc */ 248 249 _rtld_shared_enter(); 250 err = _rtld_relocate_plt_object(obj, rela, &result); 251 if (err) 252 _rtld_die(); 253 _rtld_shared_exit(); 254 255 return (caddr_t)result; 256 } 257 258 int 259 _rtld_relocate_plt_objects(const Obj_Entry *obj) 260 { 261 const Elf_Rela *rela; 262 263 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) 264 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 265 return -1; 266 267 return 0; 268 } 269
Indexes created Wed Oct 22 13:09:56 GMT 2025