/* $NetBSD: mdreloc.c,v 1.41.4.1 2023/08/04 12:55:48 martin Exp $ */ #include #ifndef lint __RCSID("$NetBSD: mdreloc.c,v 1.41.4.1 2023/08/04 12:55:48 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); #define rdbg_symname(obj, rela) \ ((obj)->strtab + (obj)->symtab[ELF_R_SYM((rela)->r_info)].st_name) 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_Rel *rel = 0, *rellim; Elf_Addr relsz = 0; Elf_Addr *where; for (; dynp->d_tag != DT_NULL; dynp++) { switch (dynp->d_tag) { case DT_REL: rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); break; case DT_RELSZ: relsz = dynp->d_un.d_val; break; } } if (rel == 0 || relsz == 0) return; rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); for (; rel < rellim; rel++) { where = (Elf_Addr *)(relocbase + rel->r_offset); *where += (Elf_Addr)relocbase; } } int _rtld_relocate_nonplt_objects(Obj_Entry *obj) { const Elf_Rel *rel; Elf_Addr target = 0; const Elf_Sym *def = NULL; const Obj_Entry *defobj = NULL; unsigned long last_symnum = ULONG_MAX; for (rel = obj->rel; rel < obj->rellim; rel++) { Elf_Addr *where; Elf_Addr tmp; unsigned long symnum; where = (Elf_Addr *)(obj->relocbase + rel->r_offset); switch (ELF_R_TYPE(rel->r_info)) { case R_TYPE(PC32): case R_TYPE(GOT32): case R_TYPE(32): case R_TYPE(GLOB_DAT): case R_TYPE(TLS_TPOFF): case R_TYPE(TLS_TPOFF32): case R_TYPE(TLS_DTPMOD32): case R_TYPE(TLS_DTPOFF32): symnum = ELF_R_SYM(rel->r_info); if (symnum != last_symnum) { last_symnum = symnum; def = _rtld_find_symdef(symnum, obj, &defobj, false); if (def == NULL) return -1; } break; default: break; } switch (ELF_R_TYPE(rel->r_info)) { case R_TYPE(NONE): break; #if 1 /* XXX should not occur */ case R_TYPE(PC32): target = (Elf_Addr)(defobj->relocbase + def->st_value); *where += target - (Elf_Addr)where; rdbg(("PC32 %s in %s --> %p in %s", rdbg_symname(obj, rel), obj->path, (void *)*where, defobj->path)); break; case R_TYPE(GOT32): #endif case R_TYPE(32): case R_TYPE(GLOB_DAT): target = (Elf_Addr)(defobj->relocbase + def->st_value); tmp = target + *where; if (*where != tmp) *where = tmp; rdbg(("32/GLOB_DAT %s in %s --> %p in %s", rdbg_symname(obj, rel), obj->path, (void *)*where, defobj->path)); break; case R_TYPE(IRELATIVE): /* IFUNC relocations are handled in _rtld_call_ifunc */ if (obj->ifunc_remaining_nonplt == 0) { obj->ifunc_remaining_nonplt = obj->rellim - rel; } /* FALL-THROUGH */ case R_TYPE(RELATIVE): *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_TPOFF): if (!defobj->tls_static && _rtld_tls_offset_allocate(__UNCONST(defobj))) return -1; *where += (Elf_Addr)(def->st_value - defobj->tlsoffset); rdbg(("TLS_TPOFF %s in %s --> %p", rdbg_symname(obj, rel), 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)(defobj->tlsoffset - def->st_value); rdbg(("TLS_TPOFF32 %s in %s --> %p", rdbg_symname(obj, rel), obj->path, (void *)*where)); break; case R_TYPE(TLS_DTPMOD32): *where = (Elf_Addr)(defobj->tlsindex); rdbg(("TLS_DTPMOD32 %s in %s --> %p", rdbg_symname(obj, rel), obj->path, (void *)*where)); break; case R_TYPE(TLS_DTPOFF32): *where = (Elf_Addr)(def->st_value); rdbg(("TLS_DTPOFF32 %s in %s --> %p", rdbg_symname(obj, rel), obj->path, (void *)*where)); break; default: rdbg(("sym = %lu, type = %lu, offset = %p, " "contents = %p, symbol = %s", (u_long)ELF_R_SYM(rel->r_info), (u_long)ELF_R_TYPE(rel->r_info), (void *)rel->r_offset, (void *)*where, rdbg_symname(obj, rel))); _rtld_error("%s: Unsupported relocation type %ld " "in non-PLT relocations", obj->path, (u_long) ELF_R_TYPE(rel->r_info)); return -1; } } return 0; } int _rtld_relocate_plt_lazy(Obj_Entry *obj) { const Elf_Rel *rel; for (rel = obj->pltrellim; rel-- > obj->pltrel; ) { Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT) || ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)); if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE)) obj->ifunc_remaining = obj->pltrellim - rel; /* 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; } static inline int _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, Elf_Addr *tp) { Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); Elf_Addr target; const Elf_Sym *def; const Obj_Entry *defobj; unsigned long info = rel->r_info; if (ELF_R_TYPE(info) == R_TYPE(IRELATIVE)) return 0; 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; target = _rtld_resolve_ifunc(defobj, def); } else { target = (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 *)target)); if (*where != target) *where = target; if (tp) *tp = target; return 0; } caddr_t _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) { const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff); Elf_Addr new_value; int err; new_value = 0; /* XXX gcc */ _rtld_shared_enter(); err = _rtld_relocate_plt_object(obj, rel, &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_Rel *rel; int err = 0; for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { err = _rtld_relocate_plt_object(obj, rel, NULL); if (err) break; } return err; } /* * i386 specific GNU variant of __tls_get_addr using register based * argument passing. */ #define DTV_MAX_INDEX(dtv) ((size_t)((dtv)[-1])) __dso_public __attribute__((__regparm__(1))) void * ___tls_get_addr(void *arg_) { size_t *arg = (size_t *)arg_; void **dtv; struct tls_tcb *tcb = __lwp_getprivate_fast(); size_t idx = arg[0], offset = arg[1]; dtv = tcb->tcb_dtv; if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL)) return (uint8_t *)dtv[idx] + offset; return _rtld_tls_get_addr(tcb, idx, offset); }