mdreloc.c revision 1.4
1 /* $NetBSD: mdreloc.c,v 1.4 2017/08/10 19:03:25 joerg Exp $ */ 2 3 /*- 4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas of 3am Software Foundry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __RCSID("$NetBSD: mdreloc.c,v 1.4 2017/08/10 19:03:25 joerg Exp $"); 35 #endif /* not lint */ 36 37 #include <sys/types.h> 38 #include <string.h> 39 40 #include "debug.h" 41 #include "rtld.h" 42 43 void _rtld_bind_start(void); 44 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 45 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 46 47 void 48 _rtld_setup_pltgot(const Obj_Entry *obj) 49 { 50 obj->pltgot[1] = (Elf_Addr) obj; 51 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 52 } 53 54 void 55 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 56 { 57 const Elf_Rel *rel = 0, *rellim; 58 Elf_Addr relsz = 0; 59 Elf_Addr *where; 60 61 for (; dynp->d_tag != DT_NULL; dynp++) { 62 switch (dynp->d_tag) { 63 case DT_REL: 64 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 65 break; 66 case DT_RELSZ: 67 relsz = dynp->d_un.d_val; 68 break; 69 } 70 } 71 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 72 for (; rel < rellim; rel++) { 73 where = (Elf_Addr *)(relocbase + rel->r_offset); 74 *where += (Elf_Addr)relocbase; 75 } 76 } 77 78 int 79 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 80 { 81 const Elf_Sym *def = NULL; 82 const Obj_Entry *defobj = NULL; 83 unsigned long last_symnum = ULONG_MAX; 84 85 for (const Elf_Rela *rela = obj->rela; rela < obj->relalim; rela++) { 86 Elf_Addr *where; 87 unsigned long symnum; 88 Elf_Addr addend; 89 90 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 91 addend = rela->r_addend; 92 93 switch (ELF_R_TYPE(rela->r_info)) { 94 case R_TYPE(ABS64): /* word B + S + A */ 95 case R_TYPE(GLOB_DAT): /* word B + S */ 96 case R_TLS_TYPE(TLS_DTPREL): 97 case R_TLS_TYPE(TLS_DTPMOD): 98 case R_TLS_TYPE(TLS_TPREL): 99 symnum = ELF_R_SYM(rela->r_info); 100 if (last_symnum != symnum) { 101 last_symnum = symnum; 102 def = _rtld_find_symdef(symnum, obj, &defobj, 103 false); 104 if (def == NULL) 105 return -1; 106 } 107 108 default: 109 break; 110 } 111 112 switch (ELF_R_TYPE(rela->r_info)) { 113 case R_TYPE(NONE): 114 break; 115 116 case R_TYPE(ABS64): /* word B + S + A */ 117 case R_TYPE(GLOB_DAT): /* word B + S */ 118 *where = addend + (Elf_Addr)defobj->relocbase + 119 def->st_value; 120 rdbg(("ABS64/GLOB_DAT %s in %s --> %p @ %p in %s", 121 obj->strtab + obj->symtab[symnum].st_name, 122 obj->path, (void *)tmp, where, defobj->path)); 123 break; 124 125 case R_TYPE(RELATIVE): /* word B + A */ 126 *where = addend + (Elf_Addr)obj->relocbase; 127 rdbg(("RELATIVE in %s --> %p", obj->path, 128 (void *)tmp)); 129 break; 130 131 case R_TYPE(COPY): 132 /* 133 * These are deferred until all other relocations have 134 * been done. All we do here is make sure that the 135 * COPY relocation is not in a shared library. They 136 * are allowed only in executable files. 137 */ 138 if (obj->isdynamic) { 139 _rtld_error( 140 "%s: Unexpected R_COPY relocation in shared library", 141 obj->path); 142 return -1; 143 } 144 rdbg(("COPY (avoid in main)")); 145 break; 146 147 case R_TLS_TYPE(TLS_DTPREL): 148 *where = addend + (Elf_Addr)(def->st_value); 149 150 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 151 obj->strtab + obj->symtab[symnum].st_name, 152 obj->path, (void *)tmp)); 153 154 break; 155 case R_TLS_TYPE(TLS_DTPMOD): 156 *where = (Elf_Addr)(defobj->tlsindex); 157 158 rdbg(("TLS_DTPMOD %s in %s --> %p", 159 obj->strtab + obj->symtab[symnum].st_name, 160 obj->path, (void *)tmp)); 161 162 break; 163 164 case R_TLS_TYPE(TLS_TPREL): 165 if (!defobj->tls_done && 166 _rtld_tls_offset_allocate(obj)) 167 return -1; 168 169 *where = (Elf_Addr)def->st_value + defobj->tlsoffset + 170 sizeof(struct tls_tcb); 171 rdbg(("TLS_TPOFF32 %s in %s --> %p", 172 obj->strtab + obj->symtab[symnum].st_name, 173 obj->path, (void *)tmp)); 174 break; 175 176 default: 177 rdbg(("sym = %lu, type = %lu, offset = %p, " 178 "contents = %p, symbol = %s", 179 (u_long)ELF_R_SYM(rela->r_info), 180 (u_long)ELF_R_TYPE(rela->r_info), 181 (void *)rela->r_offset, *where, 182 obj->strtab + obj->symtab[symnum].st_name)); 183 _rtld_error("%s: Unsupported relocation type %ld " 184 "in non-PLT relocations", 185 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 186 return -1; 187 } 188 } 189 return 0; 190 } 191 192 int 193 _rtld_relocate_plt_lazy(Obj_Entry *obj) 194 { 195 196 if (!obj->relocbase) 197 return 0; 198 199 for (const Elf_Rel *rel = obj->pltrel; rel < obj->pltrellim; rel++) { 200 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 201 202 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 203 204 /* Just relocate the GOT slots pointing into the PLT */ 205 *where += (Elf_Addr)obj->relocbase; 206 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 207 } 208 209 return 0; 210 } 211 212 static int 213 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 214 Elf_Addr *tp) 215 { 216 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 217 Elf_Addr new_value; 218 const Elf_Sym *def; 219 const Obj_Entry *defobj; 220 unsigned long info = rel->r_info; 221 222 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 223 224 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 225 if (__predict_false(def == NULL)) 226 return -1; 227 if (__predict_false(def == &_rtld_sym_zero)) 228 return 0; 229 230 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 231 if (tp == NULL) 232 return 0; 233 new_value = _rtld_resolve_ifunc(defobj, def); 234 } else { 235 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 236 } 237 rdbg(("bind now/fixup in %s --> old=%p new=%p", 238 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 239 if (*where != new_value) 240 *where = new_value; 241 if (tp) 242 *tp = new_value; 243 244 return 0; 245 } 246 247 caddr_t 248 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 249 { 250 const Elf_Rel *rel = obj->pltrel + reloff; 251 Elf_Addr new_value = 0; /* XXX gcc */ 252 253 _rtld_shared_enter(); 254 int err = _rtld_relocate_plt_object(obj, rel, &new_value); 255 if (err) 256 _rtld_die(); 257 _rtld_shared_exit(); 258 259 return (caddr_t)new_value; 260 } 261 int 262 _rtld_relocate_plt_objects(const Obj_Entry *obj) 263 { 264 const Elf_Rel *rel; 265 int err = 0; 266 267 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 268 err = _rtld_relocate_plt_object(obj, rel, NULL); 269 if (err) 270 break; 271 } 272 273 return err; 274 } 275
Indexes created Thu Oct 02 14:10:14 GMT 2025