/* $NetBSD: mdreloc.c,v 1.35.14.1 2023/08/01 16:34:56 martin Exp $ */ #include #ifndef lint __RCSID("$NetBSD: mdreloc.c,v 1.35.14.1 2023/08/01 16:34:56 martin Exp $"); #endif /* not lint */ #include #include #include "debug.h" #include "rtld.h" void _rtld_bind_start(void); void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); static inline int _rtld_relocate_plt_object(const Obj_Entry *, const Elf_Rela *, Elf_Addr *); void _rtld_setup_pltgot(const Obj_Entry *obj) { obj->pltgot[1] = (Elf_Addr) obj; obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; } void _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) { const Elf_Rela *rela = 0, *relalim; Elf_Addr relasz = 0; Elf_Addr *where; for (; dynp->d_tag != DT_NULL; dynp++) { switch (dynp->d_tag) { case DT_RELA: rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); break; case DT_RELASZ: relasz = dynp->d_un.d_val; break; } } relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); for (; rela < relalim; rela++) { where = (Elf_Addr *)(relocbase + rela->r_offset); *where = (Elf_Addr)(relocbase + rela->r_addend); } } int _rtld_relocate_nonplt_objects(Obj_Entry *obj) { const Elf_Rela *rela; const Elf_Sym *def = NULL; const Obj_Entry *defobj = NULL; unsigned long last_symnum = ULONG_MAX; for (rela = obj->rela; rela < obj->relalim; rela++) { Elf_Addr *where; Elf_Addr tmp; unsigned long symnum; where = (Elf_Addr *)(obj->relocbase + rela->r_offset); switch (ELF_R_TYPE(rela->r_info)) { case R_TYPE(GOT32): case R_TYPE(REL32): case R_TYPE(DIR32): case R_TYPE(GLOB_DAT): case R_TYPE(TLS_DTPOFF32): case R_TYPE(TLS_DTPMOD32): case R_TYPE(TLS_TPOFF32): symnum = ELF_R_SYM(rela->r_info); if (last_symnum != symnum) { last_symnum = symnum; def = _rtld_find_symdef(symnum, obj, &defobj, false); if (def == NULL) return -1; } break; default: break; } switch (ELF_R_TYPE(rela->r_info)) { case R_TYPE(NONE): break; #if 1 /* XXX should not occur */ case R_TYPE(GOT32): tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); if (*where != tmp) *where = tmp; rdbg(("GOT32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(REL32): tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend) - (Elf_Addr)where; if (*where != tmp) *where = tmp; rdbg(("PC32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; #endif case R_TYPE(DIR32): tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); if (*where != tmp) *where = tmp; rdbg(("32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(GLOB_DAT): tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + rela->r_addend; if (*where != tmp) *where = tmp; rdbg(("GLOB_DAT %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(RELATIVE): if (rela->r_addend) *where = (Elf_Addr)obj->relocbase + rela->r_addend; else *where += (Elf_Addr)obj->relocbase; rdbg(("RELATIVE in %s --> %p", obj->path, (void *)*where)); break; case R_TYPE(COPY): /* * These are deferred until all other relocations have * been done. All we do here is make sure that the * COPY relocation is not in a shared library. They * are allowed only in executable files. */ if (obj->isdynamic) { _rtld_error( "%s: Unexpected R_COPY relocation in shared library", obj->path); return -1; } rdbg(("COPY (avoid in main)")); break; case R_TYPE(TLS_DTPOFF32): *where = (Elf_Addr)(def->st_value); rdbg(("TLS_DTPOFF32 %s in %s --> %p", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where)); break; case R_TYPE(TLS_DTPMOD32): *where = (Elf_Addr)(defobj->tlsindex); rdbg(("TLS_DTPMOD32 %s in %s --> %p", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where)); break; case R_TYPE(TLS_TPOFF32): if (!defobj->tls_static && _rtld_tls_offset_allocate(__UNCONST(defobj))) return -1; *where = (Elf_Addr)def->st_value + rela->r_addend + defobj->tlsoffset + sizeof(struct tls_tcb); rdbg(("TLS_TPOFF32 %s in %s --> %p", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where)); break; default: rdbg(("sym = %lu, type = %lu, offset = %p, " "addend = %p, contents = %p, symbol = %s", (u_long)ELF_R_SYM(rela->r_info), (u_long)ELF_R_TYPE(rela->r_info), (void *)rela->r_offset, (void *)rela->r_addend, (void *)*where, obj->strtab + obj->symtab[symnum].st_name)); _rtld_error("%s: Unsupported relocation type %ld " "in non-PLT relocations", obj->path, (u_long) ELF_R_TYPE(rela->r_info)); return -1; } } return 0; } int _rtld_relocate_plt_lazy(Obj_Entry *obj) { const Elf_Rela *rela; if (!obj->relocbase) return 0; for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); /* Just relocate the GOT slots pointing into the PLT */ *where += (Elf_Addr)obj->relocbase; rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); } return 0; } caddr_t _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) { const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); Elf_Addr new_value; int err; new_value = 0; /* XXX gcc */ _rtld_shared_enter(); err = _rtld_relocate_plt_object(obj, rela, &new_value); if (err) _rtld_die(); _rtld_shared_exit(); return (caddr_t)new_value; } int _rtld_relocate_plt_objects(const Obj_Entry *obj) { const Elf_Rela *rela = obj->pltrela; for (; rela < obj->pltrelalim; rela++) if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) return -1; return 0; } static inline int _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) { Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); Elf_Addr new_value; const Elf_Sym *def; const Obj_Entry *defobj; unsigned long info = rela->r_info; assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); if (__predict_false(def == NULL)) return -1; if (__predict_false(def == &_rtld_sym_zero)) return 0; if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { if (tp == NULL) return 0; new_value = _rtld_resolve_ifunc(defobj, def); } else { new_value = (Elf_Addr)(defobj->relocbase + def->st_value); } rdbg(("bind now/fixup in %s --> old=%p new=%p", defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); if (*where != new_value) *where = new_value; if (tp) *tp = new_value; return 0; }