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NetBSD/libexec/ld.elf_so/headers.c

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/* $NetBSD: headers.c,v 1.42 2012/07/22 09:16:35 martin Exp $ */
/*
* Copyright 1996 John D. Polstra.
* Copyright 1996 Matt Thomas <matt@3am-software.com>
* Copyright 2002 Charles M. Hannum <root@ihack.net>
* 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 <jdp@polstra.com>.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: headers.c,v 1.42 2012/07/22 09:16:35 martin Exp $");
#endif /* not lint */
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/bitops.h>
#include <dirent.h>
#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;
bool use_pltrel = false;
bool use_pltrela = false;
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:
use_pltrel = dynp->d_un.d_val == DT_REL;
use_pltrela = dynp->d_un.d_val == DT_RELA;
assert(use_pltrel || use_pltrela);
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_VERNEED:
obj->verneed = (const Elf_Verneed *)
(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_VERNEEDNUM:
obj->verneednum = dynp->d_un.d_val;
break;
case DT_VERDEF:
obj->verdef = (const Elf_Verdef *)
(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_VERDEFNUM:
obj->verdefnum = dynp->d_un.d_val;
break;
case DT_VERSYM:
obj->versyms = (const Elf_Versym *)
(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_HASH:
{
const Elf_Symindx *hashtab = (const Elf_Symindx *)
(obj->relocbase + dynp->d_un.d_ptr);
if (hashtab[0] > UINT32_MAX)
obj->nbuckets = UINT32_MAX;
else
obj->nbuckets = hashtab[0];
obj->nchains = hashtab[1];
obj->buckets = hashtab + 2;
obj->chains = obj->buckets + obj->nbuckets;
/*
* Should really be in _rtld_relocate_objects,
* but _rtld_symlook_obj might be used before.
*/
if (obj->nbuckets) {
fast_divide32_prepare(obj->nbuckets,
&obj->nbuckets_m,
&obj->nbuckets_s1,
&obj->nbuckets_s2);
}
}
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
#ifdef __powerpc__
case DT_PPC_GOT:
obj->gotptr = (Elf_Addr *)(obj->relocbase + dynp->d_un.d_ptr);
break;
#endif
case DT_FLAGS_1:
obj->z_now =
((dynp->d_un.d_val & DF_1_BIND_NOW) != 0);
obj->z_nodelete =
((dynp->d_un.d_val & DF_1_NODELETE) != 0);
obj->z_initfirst =
((dynp->d_un.d_val & DF_1_INITFIRST) != 0);
obj->z_noopen =
((dynp->d_un.d_val & DF_1_NOOPEN) != 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 (use_pltrel) {
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 (use_pltrela) {
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;
Elf_Addr vaddr;
obj = _rtld_obj_new();
for (ph = phdr; ph < phlimit; ++ph) {
if (ph->p_type != PT_PHDR)
continue;
obj->phdr = (void *)(uintptr_t)phdr->p_vaddr;
obj->phsize = phdr->p_memsz;
obj->relocbase = (caddr_t)((uintptr_t)phdr - (uintptr_t)ph->p_vaddr);
dbg(("headers: phdr %p phsize %zu relocbase %lx", obj->phdr,
obj->phsize, (long)obj->relocbase));
break;
}
for (ph = phdr; ph < phlimit; ++ph) {
vaddr = (Elf_Addr)(uintptr_t)(obj->relocbase + ph->p_vaddr);
switch (ph->p_type) {
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->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;
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
case PT_TLS:
obj->tlsindex = 1;
obj->tlssize = ph->p_memsz;
obj->tlsalign = ph->p_align;
obj->tlsinitsize = ph->p_filesz;
obj->tlsinit = (void *)(uintptr_t)ph->p_vaddr;
break;
#endif
}
}
assert(nsegs == 2);
obj->entry = entry;
return obj;
}
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