/* $NetBSD: mdreloc.c,v 1.44.4.2 2024/08/07 10:45:41 martin Exp $ */ #include #ifndef lint __RCSID("$NetBSD: mdreloc.c,v 1.44.4.2 2024/08/07 10:45:41 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); 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; } } rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); for (; rel < rellim; rel++) { where = (Elf_Addr *)(relocbase + rel->r_offset); *where += (Elf_Addr)relocbase; } } /* * It is possible for the compiler to emit relocations for unaligned data. * We handle this situation with these inlines. */ #define RELOC_ALIGNED_P(x) \ (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) static inline Elf_Addr load_ptr(void *where) { Elf_Addr res; memcpy(&res, where, sizeof(res)); return (res); } static inline void store_ptr(void *where, Elf_Addr val) { memcpy(where, &val, sizeof(val)); } int _rtld_relocate_nonplt_objects(Obj_Entry *obj) { const Elf_Rel *rel; 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(PC24): /* word32 S - P + A */ case R_TYPE(ABS32): /* word32 B + S + A */ case R_TYPE(GLOB_DAT): /* word32 B + S */ case R_TYPE(TLS_DTPOFF32): case R_TYPE(TLS_DTPMOD32): case R_TYPE(TLS_TPOFF32): symnum = ELF_R_SYM(rel->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(rel->r_info)) { case R_TYPE(NONE): break; #if 1 /* XXX should not occur */ case R_TYPE(PC24): { /* word32 S - P + A */ Elf32_Sword addend; /* * Extract addend and sign-extend if needed. */ addend = *where; if (addend & 0x00800000) addend |= 0xff000000; tmp = (Elf_Addr)obj->relocbase + def->st_value - (Elf_Addr)where + (addend << 2); if ((tmp & 0xfe000000) != 0xfe000000 && (tmp & 0xfe000000) != 0) { _rtld_error( "%s: R_ARM_PC24 relocation @ %p to %s failed " "(displacement %ld (%#lx) out of range)", obj->path, where, obj->strtab + obj->symtab[ ELF_R_SYM(rel->r_info)].st_name, (long) tmp, (long) tmp); return -1; } tmp >>= 2; *where = (*where & 0xff000000) | (tmp & 0x00ffffff); rdbg(("PC24 %s in %s --> %p @ %p in %s", obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] .st_name, obj->path, (void *)*where, where, defobj->path)); break; } #endif case R_TYPE(ABS32): /* word32 B + S + A */ case R_TYPE(GLOB_DAT): /* word32 B + S */ if (__predict_true(RELOC_ALIGNED_P(where))) { tmp = *where + (Elf_Addr)defobj->relocbase + def->st_value; /* Set the Thumb bit, if needed. */ if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) tmp |= 1; *where = tmp; } else { tmp = load_ptr(where) + (Elf_Addr)defobj->relocbase + def->st_value; /* Set the Thumb bit, if needed. */ if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) tmp |= 1; store_ptr(where, tmp); } rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] .st_name, obj->path, (void *)tmp, 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): /* word32 B + A */ if (__predict_true(RELOC_ALIGNED_P(where))) { tmp = *where + (Elf_Addr)obj->relocbase; *where = tmp; } else { tmp = load_ptr(where) + (Elf_Addr)obj->relocbase; store_ptr(where, tmp); } rdbg(("RELATIVE in %s --> %p", obj->path, (void *)tmp)); 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): tmp = (Elf_Addr)(def->st_value); if (__predict_true(RELOC_ALIGNED_P(where))) *where = tmp; else store_ptr(where, tmp); rdbg(("TLS_DTPOFF32 %s in %s --> %p", obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] .st_name, obj->path, (void *)tmp)); break; case R_TYPE(TLS_DTPMOD32): tmp = (Elf_Addr)(defobj->tlsindex); if (__predict_true(RELOC_ALIGNED_P(where))) *where = tmp; else store_ptr(where, tmp); rdbg(("TLS_DTPMOD32 %s in %s --> %p", obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] .st_name, obj->path, (void *)tmp)); break; case R_TYPE(TLS_TPOFF32): if (!defobj->tls_static && _rtld_tls_offset_allocate(__UNCONST(defobj))) return -1; if (__predict_true(RELOC_ALIGNED_P(where))) tmp = *where; else tmp = load_ptr(where); tmp += (Elf_Addr)def->st_value + defobj->tlsoffset + sizeof(struct tls_tcb); if (__predict_true(RELOC_ALIGNED_P(where))) *where = tmp; else store_ptr(where, tmp); rdbg(("TLS_TPOFF32 %s in %s --> %p", obj->strtab + obj->symtab[ELF_R_SYM(rel->r_info)] .st_name, obj->path, (void *)tmp)); break; default: rdbg(("sym = %lu, type = %lu, offset = %p, " "contents = %p", (u_long)ELF_R_SYM(rel->r_info), (u_long)ELF_R_TYPE(rel->r_info), (void *)rel->r_offset, (void *)load_ptr(where))); _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(JUMP_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 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 new_value; const Elf_Sym *def; const Obj_Entry *defobj; unsigned long info = rel->r_info; assert(ELF_R_TYPE(info) == R_TYPE(JUMP_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); } /* Set the Thumb bit, if needed. */ if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) new_value |= 1; 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; } 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 = 0; /* XXX gcc */ int err; _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; }