/* $NetBSD: reloc.c,v 1.97 2009/09/24 21:21:34 pooka Exp $ */ /* * Copyright 1996 John D. Polstra. * Copyright 1996 Matt Thomas * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by John Polstra. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * Dynamic linker for ELF. * * John Polstra . */ #include #ifndef lint __RCSID("$NetBSD: reloc.c,v 1.97 2009/09/24 21:21:34 pooka Exp $"); #endif /* not lint */ #include #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" #ifndef RTLD_INHIBIT_COPY_RELOCS static int _rtld_do_copy_relocation(const Obj_Entry *, const Elf_Rela *); static int _rtld_do_copy_relocation(const Obj_Entry *dstobj, const Elf_Rela *rela) { void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset); const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); const char *name = dstobj->strtab + dstsym->st_name; unsigned long hash = _rtld_elf_hash(name); size_t size = dstsym->st_size; const void *srcaddr; const Elf_Sym *srcsym = NULL; Obj_Entry *srcobj; for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) if ((srcsym = _rtld_symlook_obj(name, hash, srcobj, false)) != NULL) break; if (srcobj == NULL) { _rtld_error("Undefined symbol \"%s\" referenced from COPY" " relocation in %s", name, dstobj->path); return (-1); } srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value); (void)memcpy(dstaddr, srcaddr, size); rdbg(("COPY %s %s %s --> src=%p dst=%p size %ld", dstobj->path, srcobj->path, name, (void *)srcaddr, (void *)dstaddr, (long)size)); return (0); } #endif /* RTLD_INHIBIT_COPY_RELOCS */ /* * Process the special R_xxx_COPY relocations in the main program. These * copy data from a shared object into a region in the main program's BSS * segment. * * Returns 0 on success, -1 on failure. */ int _rtld_do_copy_relocations(const Obj_Entry *dstobj) { #ifndef RTLD_INHIBIT_COPY_RELOCS /* COPY relocations are invalid elsewhere */ assert(!dstobj->isdynamic); if (dstobj->rel != NULL) { const Elf_Rel *rel; for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) { if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) { Elf_Rela ourrela; ourrela.r_info = rel->r_info; ourrela.r_offset = rel->r_offset; ourrela.r_addend = 0; if (_rtld_do_copy_relocation(dstobj, &ourrela) < 0) return (-1); } } } if (dstobj->rela != NULL) { const Elf_Rela *rela; for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) { if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) { if (_rtld_do_copy_relocation(dstobj, rela) < 0) return (-1); } } } #endif /* RTLD_INHIBIT_COPY_RELOCS */ return (0); } /* * Relocate newly-loaded shared objects. The argument is a pointer to * the Obj_Entry for the first such object. All objects from the first * to the end of the list of objects are relocated. Returns 0 on success, * or -1 on failure. */ int _rtld_relocate_objects(Obj_Entry *first, bool bind_now) { Obj_Entry *obj; int ok = 1; for (obj = first; obj != NULL; obj = obj->next) { if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || obj->symtab == NULL || obj->strtab == NULL) { _rtld_error("%s: Shared object has no run-time" " symbol table", obj->path); return -1; } rdbg((" relocating %s (%ld/%ld rel/rela, %ld/%ld plt rel/rela)", obj->path, (long)(obj->rellim - obj->rel), (long)(obj->relalim - obj->rela), (long)(obj->pltrellim - obj->pltrel), (long)(obj->pltrelalim - obj->pltrela))); if (obj->textrel) { /* * There are relocations to the write-protected text * segment. */ if (mprotect(obj->mapbase, obj->textsize, PROT_READ | PROT_WRITE | PROT_EXEC) == -1) { _rtld_error("%s: Cannot write-enable text " "segment: %s", obj->path, xstrerror(errno)); return -1; } } dbg(("doing non-PLT relocations")); if (_rtld_relocate_nonplt_objects(obj) < 0) ok = 0; if (obj->textrel) { /* Re-protected the text segment. */ if (mprotect(obj->mapbase, obj->textsize, PROT_READ | PROT_EXEC) == -1) { _rtld_error("%s: Cannot write-protect text " "segment: %s", obj->path, xstrerror(errno)); return -1; } } dbg(("doing lazy PLT binding")); if (_rtld_relocate_plt_lazy(obj) < 0) ok = 0; #if defined(__hppa__) bind_now = 1; #endif if (bind_now) { dbg(("doing immediate PLT binding")); if (_rtld_relocate_plt_objects(obj) < 0) ok = 0; } if (!ok) return -1; (void)dlerror(); /* clear any errors since all is good */ /* Set some sanity-checking numbers in the Obj_Entry. */ obj->magic = RTLD_MAGIC; obj->version = RTLD_VERSION; /* Fill in the dynamic linker entry points. */ obj->dlopen = dlopen; obj->dlsym = dlsym; obj->dlerror = dlerror; obj->dlclose = dlclose; obj->dladdr = dladdr; obj->dlinfo = dlinfo; dbg(("fixing up PLTGOT")); /* Set the special PLTGOT entries. */ if (obj->pltgot != NULL) _rtld_setup_pltgot(obj); } return 0; }