336 lines
8.5 KiB
C
336 lines
8.5 KiB
C
/* $NetBSD: headers.c,v 1.26 2007/12/29 01:44:03 christos Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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* Copyright 1996 Matt Thomas <matt@3am-software.com>
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* Copyright 2002 Charles M. Hannum <root@ihack.net>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Polstra.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Dynamic linker for ELF.
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*
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* John Polstra <jdp@polstra.com>.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: headers.c,v 1.26 2007/12/29 01:44:03 christos Exp $");
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#endif /* not lint */
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <dirent.h>
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#include "debug.h"
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#include "rtld.h"
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/*
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* Process a shared object's DYNAMIC section, and save the important
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* information in its Obj_Entry structure.
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*/
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void
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_rtld_digest_dynamic(const char *execname, Obj_Entry *obj)
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{
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Elf_Dyn *dynp;
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Needed_Entry **needed_tail = &obj->needed;
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const Elf_Dyn *dyn_rpath = NULL;
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Elf_Sword plttype = DT_NULL;
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Elf_Addr relsz = 0, relasz = 0;
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Elf_Addr pltrel = 0, pltrelsz = 0;
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Elf_Addr init = 0, fini = 0;
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for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; ++dynp) {
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switch (dynp->d_tag) {
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case DT_REL:
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obj->rel = (const Elf_Rel *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELSZ:
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relsz = dynp->d_un.d_val;
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break;
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case DT_RELENT:
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assert(dynp->d_un.d_val == sizeof(Elf_Rel));
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break;
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case DT_JMPREL:
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pltrel = dynp->d_un.d_ptr;
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break;
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case DT_PLTRELSZ:
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pltrelsz = dynp->d_un.d_val;
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break;
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case DT_RELA:
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obj->rela = (const Elf_Rela *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELASZ:
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relasz = dynp->d_un.d_val;
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break;
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case DT_RELAENT:
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assert(dynp->d_un.d_val == sizeof(Elf_Rela));
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break;
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case DT_PLTREL:
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plttype = dynp->d_un.d_val;
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assert(plttype == DT_REL || plttype == DT_RELA);
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break;
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case DT_SYMTAB:
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obj->symtab = (const Elf_Sym *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_SYMENT:
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assert(dynp->d_un.d_val == sizeof(Elf_Sym));
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break;
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case DT_STRTAB:
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obj->strtab = (const char *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_STRSZ:
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obj->strsize = dynp->d_un.d_val;
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break;
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case DT_HASH:
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{
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const Elf_Word *hashtab = (const Elf_Word *)
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(obj->relocbase + dynp->d_un.d_ptr);
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obj->nbuckets = hashtab[0];
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obj->nchains = hashtab[1];
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obj->buckets = hashtab + 2;
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obj->chains = obj->buckets + obj->nbuckets;
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}
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break;
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case DT_NEEDED:
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{
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Needed_Entry *nep = NEW(Needed_Entry);
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nep->name = dynp->d_un.d_val;
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nep->obj = NULL;
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nep->next = NULL;
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*needed_tail = nep;
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needed_tail = &nep->next;
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}
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break;
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case DT_PLTGOT:
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obj->pltgot = (Elf_Addr *)
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(obj->relocbase + dynp->d_un.d_ptr);
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break;
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case DT_TEXTREL:
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obj->textrel = true;
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break;
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case DT_SYMBOLIC:
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obj->symbolic = true;
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break;
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case DT_RPATH:
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/*
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* We have to wait until later to process this, because
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* we might not have gotten the address of the string
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* table yet.
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*/
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dyn_rpath = dynp;
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break;
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case DT_SONAME:
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/* Not used by the dynamic linker. */
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break;
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case DT_INIT:
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init = dynp->d_un.d_ptr;
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break;
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case DT_FINI:
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fini = dynp->d_un.d_ptr;
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break;
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/*
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* Don't process DT_DEBUG on MIPS as the dynamic section
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* is mapped read-only. DT_MIPS_RLD_MAP is used instead.
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* XXX: n32/n64 may use DT_DEBUG, not sure yet.
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*/
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#ifndef __mips__
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case DT_DEBUG:
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#ifdef RTLD_LOADER
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dynp->d_un.d_ptr = (Elf_Addr)&_rtld_debug;
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#endif
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break;
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#endif
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#ifdef __mips__
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case DT_MIPS_LOCAL_GOTNO:
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obj->local_gotno = dynp->d_un.d_val;
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break;
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case DT_MIPS_SYMTABNO:
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obj->symtabno = dynp->d_un.d_val;
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break;
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case DT_MIPS_GOTSYM:
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obj->gotsym = dynp->d_un.d_val;
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break;
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case DT_MIPS_RLD_MAP:
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#ifdef RTLD_LOADER
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*((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr)
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&_rtld_debug;
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#endif
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break;
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#endif
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case DT_FLAGS_1:
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obj->initfirst =
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((dynp->d_un.d_val & DF_1_INITFIRST) != 0);
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break;
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}
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}
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obj->rellim = (const Elf_Rel *)((caddr_t)obj->rel + relsz);
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obj->relalim = (const Elf_Rela *)((caddr_t)obj->rela + relasz);
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if (plttype == DT_REL) {
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obj->pltrel = (const Elf_Rel *)(obj->relocbase + pltrel);
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obj->pltrellim = (const Elf_Rel *)(obj->relocbase + pltrel + pltrelsz);
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obj->pltrelalim = 0;
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/* On PPC and SPARC, at least, REL(A)SZ may include JMPREL.
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Trim rel(a)lim to save time later. */
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if (obj->rellim && obj->pltrel &&
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obj->rellim > obj->pltrel &&
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obj->rellim <= obj->pltrellim)
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obj->rellim = obj->pltrel;
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} else if (plttype == DT_RELA) {
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obj->pltrela = (const Elf_Rela *)(obj->relocbase + pltrel);
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obj->pltrellim = 0;
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obj->pltrelalim = (const Elf_Rela *)(obj->relocbase + pltrel + pltrelsz);
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/* On PPC and SPARC, at least, REL(A)SZ may include JMPREL.
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Trim rel(a)lim to save time later. */
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if (obj->relalim && obj->pltrela &&
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obj->relalim > obj->pltrela &&
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obj->relalim <= obj->pltrelalim)
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obj->relalim = obj->pltrela;
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}
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#if defined(RTLD_LOADER) && defined(__HAVE_FUNCTION_DESCRIPTORS)
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if (init != 0)
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obj->init = (void (*)(void))
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_rtld_function_descriptor_alloc(obj, NULL, init);
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if (fini != 0)
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obj->fini = (void (*)(void))
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_rtld_function_descriptor_alloc(obj, NULL, fini);
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#else
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if (init != 0)
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obj->init = (void (*)(void))
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(obj->relocbase + init);
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if (fini != 0)
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obj->fini = (void (*)(void))
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(obj->relocbase + fini);
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#endif
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if (dyn_rpath != NULL) {
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_rtld_add_paths(execname, &obj->rpaths, obj->strtab +
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dyn_rpath->d_un.d_val);
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}
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}
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/*
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* Process a shared object's program header. This is used only for the
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* main program, when the kernel has already loaded the main program
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* into memory before calling the dynamic linker. It creates and
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* returns an Obj_Entry structure.
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*/
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Obj_Entry *
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_rtld_digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry)
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{
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Obj_Entry *obj;
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const Elf_Phdr *phlimit = phdr + phnum;
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const Elf_Phdr *ph;
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int nsegs = 0;
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ptrdiff_t relocoffs = 0;
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Elf_Addr vaddr;
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obj = _rtld_obj_new();
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for (ph = phdr; ph < phlimit; ++ph) {
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vaddr = ph->p_vaddr + relocoffs;
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dbg(("headers: relocoffs = %lx\n", (long)relocoffs));
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switch (ph->p_type) {
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case PT_PHDR:
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relocoffs = (char *)phdr - (char *)ph->p_vaddr;
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break;
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case PT_INTERP:
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obj->interp = (const char *)vaddr;
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break;
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case PT_LOAD:
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assert(nsegs < 2);
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if (nsegs == 0) { /* First load segment */
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obj->vaddrbase = round_down(vaddr);
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obj->mapbase = (caddr_t)obj->vaddrbase;
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obj->relocbase = (void *)relocoffs;
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obj->textsize = round_up(vaddr + ph->p_memsz) -
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obj->vaddrbase;
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} else { /* Last load segment */
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obj->mapsize = round_up(vaddr + ph->p_memsz) -
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obj->vaddrbase;
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}
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++nsegs;
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break;
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case PT_DYNAMIC:
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obj->dynamic = (Elf_Dyn *)vaddr;
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break;
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}
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}
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assert(nsegs == 2);
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obj->entry = entry;
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return obj;
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}
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