/* $NetBSD: headers.c,v 1.28 2009/04/12 13:29:29 lukem Exp $ */ /* * Copyright 1996 John D. Polstra. * Copyright 1996 Matt Thomas * Copyright 2002 Charles M. Hannum * 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: headers.c,v 1.28 2009/04/12 13:29:29 lukem Exp $"); #endif /* not lint */ #include #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" /* * Process a shared object's DYNAMIC section, and save the important * information in its Obj_Entry structure. */ void _rtld_digest_dynamic(const char *execname, Obj_Entry *obj) { Elf_Dyn *dynp; Needed_Entry **needed_tail = &obj->needed; const Elf_Dyn *dyn_rpath = NULL; Elf_Sword plttype = DT_NULL; Elf_Addr relsz = 0, relasz = 0; Elf_Addr pltrel = 0, pltrelsz = 0; Elf_Addr init = 0, fini = 0; for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) { switch (dynp->d_tag) { case DT_REL: obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELSZ: relsz = dynp->d_un.d_val; break; case DT_RELENT: assert(dynp->d_un.d_val == sizeof(Elf_Rel)); break; case DT_JMPREL: pltrel = dynp->d_un.d_ptr; break; case DT_PLTRELSZ: pltrelsz = dynp->d_un.d_val; break; case DT_RELA: obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELASZ: relasz = dynp->d_un.d_val; break; case DT_RELAENT: assert(dynp->d_un.d_val == sizeof(Elf_Rela)); break; case DT_PLTREL: plttype = dynp->d_un.d_val; assert(plttype == DT_REL || plttype == DT_RELA); break; case DT_SYMTAB: obj->symtab = (const Elf_Sym *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_SYMENT: assert(dynp->d_un.d_val == sizeof(Elf_Sym)); break; case DT_STRTAB: obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_STRSZ: obj->strsize = dynp->d_un.d_val; break; case DT_HASH: { const Elf_Word *hashtab = (const Elf_Word *) (obj->relocbase + dynp->d_un.d_ptr); obj->nbuckets = hashtab[0]; obj->nchains = hashtab[1]; obj->buckets = hashtab + 2; obj->chains = obj->buckets + obj->nbuckets; } break; case DT_NEEDED: { Needed_Entry *nep = NEW(Needed_Entry); nep->name = dynp->d_un.d_val; nep->obj = NULL; nep->next = NULL; *needed_tail = nep; needed_tail = &nep->next; } break; case DT_PLTGOT: obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_TEXTREL: obj->textrel = true; break; case DT_SYMBOLIC: obj->symbolic = true; break; case DT_RPATH: /* * We have to wait until later to process this, because * we might not have gotten the address of the string * table yet. */ dyn_rpath = dynp; break; case DT_SONAME: /* Not used by the dynamic linker. */ break; case DT_INIT: init = dynp->d_un.d_ptr; break; case DT_FINI: fini = dynp->d_un.d_ptr; break; /* * Don't process DT_DEBUG on MIPS as the dynamic section * is mapped read-only. DT_MIPS_RLD_MAP is used instead. * XXX: n32/n64 may use DT_DEBUG, not sure yet. */ #ifndef __mips__ case DT_DEBUG: #ifdef RTLD_LOADER dynp->d_un.d_ptr = (Elf_Addr)&_rtld_debug; #endif break; #endif #ifdef __mips__ case DT_MIPS_LOCAL_GOTNO: obj->local_gotno = dynp->d_un.d_val; break; case DT_MIPS_SYMTABNO: obj->symtabno = dynp->d_un.d_val; break; case DT_MIPS_GOTSYM: obj->gotsym = dynp->d_un.d_val; break; case DT_MIPS_RLD_MAP: #ifdef RTLD_LOADER *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &_rtld_debug; #endif break; #endif case DT_FLAGS_1: obj->initfirst = ((dynp->d_un.d_val & DF_1_INITFIRST) != 0); break; } } obj->rellim = (const Elf_Rel *)((const uint8_t *)obj->rel + relsz); obj->relalim = (const Elf_Rela *)((const uint8_t *)obj->rela + relasz); if (plttype == DT_REL) { obj->pltrel = (const Elf_Rel *)(obj->relocbase + pltrel); obj->pltrellim = (const Elf_Rel *)(obj->relocbase + pltrel + pltrelsz); obj->pltrelalim = 0; /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. Trim rel(a)lim to save time later. */ if (obj->rellim && obj->pltrel && obj->rellim > obj->pltrel && obj->rellim <= obj->pltrellim) obj->rellim = obj->pltrel; } else if (plttype == DT_RELA) { obj->pltrela = (const Elf_Rela *)(obj->relocbase + pltrel); obj->pltrellim = 0; obj->pltrelalim = (const Elf_Rela *)(obj->relocbase + pltrel + pltrelsz); /* On PPC and SPARC, at least, REL(A)SZ may include JMPREL. Trim rel(a)lim to save time later. */ if (obj->relalim && obj->pltrela && obj->relalim > obj->pltrela && obj->relalim <= obj->pltrelalim) obj->relalim = obj->pltrela; } #if defined(RTLD_LOADER) && defined(__HAVE_FUNCTION_DESCRIPTORS) if (init != 0) obj->init = (void (*)(void)) _rtld_function_descriptor_alloc(obj, NULL, init); if (fini != 0) obj->fini = (void (*)(void)) _rtld_function_descriptor_alloc(obj, NULL, fini); #else if (init != 0) obj->init = (void (*)(void)) (obj->relocbase + init); if (fini != 0) obj->fini = (void (*)(void)) (obj->relocbase + fini); #endif if (dyn_rpath != NULL) { _rtld_add_paths(execname, &obj->rpaths, obj->strtab + dyn_rpath->d_un.d_val); } } /* * Process a shared object's program header. This is used only for the * main program, when the kernel has already loaded the main program * into memory before calling the dynamic linker. It creates and * returns an Obj_Entry structure. */ Obj_Entry * _rtld_digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry) { Obj_Entry *obj; const Elf_Phdr *phlimit = phdr + phnum; const Elf_Phdr *ph; int nsegs = 0; ptrdiff_t relocoffs = 0; Elf_Addr vaddr; obj = _rtld_obj_new(); for (ph = phdr; ph < phlimit; ++ph) { vaddr = ph->p_vaddr + relocoffs; dbg(("headers: relocoffs = %lx\n", (long)relocoffs)); switch (ph->p_type) { case PT_PHDR: relocoffs = (uintptr_t)phdr - (uintptr_t)ph->p_vaddr; break; case PT_INTERP: obj->interp = (const char *)(uintptr_t)vaddr; break; case PT_LOAD: assert(nsegs < 2); if (nsegs == 0) { /* First load segment */ obj->vaddrbase = round_down(vaddr); obj->mapbase = (caddr_t)(uintptr_t)obj->vaddrbase; obj->relocbase = (void *)relocoffs; obj->textsize = round_up(vaddr + ph->p_memsz) - obj->vaddrbase; } else { /* Last load segment */ obj->mapsize = round_up(vaddr + ph->p_memsz) - obj->vaddrbase; } ++nsegs; break; case PT_DYNAMIC: obj->dynamic = (Elf_Dyn *)(uintptr_t)vaddr; break; } } assert(nsegs == 2); obj->entry = entry; return obj; }