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/* $OpenBSD: boot.c,v 1.15 2017/01/09 22:51:04 kettenis Exp $ */
/*
* Copyright (c) 1998 Per Fogelstrom, Opsycon AB
*
* 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.
*
* 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.
*
*/
/*
* IMPORTANT: any functions below are NOT protected by SSP. Please
* do not add anything except what is required to reach GOT with
* an adjustment.
*/
#define _DYN_LOADER
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/exec.h>
#include <sys/sysctl.h>
#include <nlist.h>
#include <link.h>
#include <dlfcn.h>
#include "syscall.h"
#include "archdep.h"
#include "stdlib.h"
#include "../../lib/csu/os-note-elf.h"
#if RELOC_TAG == DT_RELA
typedef Elf_RelA RELOC_TYPE;
#elif RELOC_TAG == DT_REL
typedef Elf_Rel RELOC_TYPE;
#else
# error "unknown RELOC_TAG"
#endif
/* The set of dynamic tags that we're interested in for bootstrapping */
struct boot_dyn {
RELOC_TYPE *dt_reloc; /* DT_RELA or DT_REL */
Elf_Addr dt_relocsz; /* DT_RELASZ or DT_RELSZ */
Elf_Addr *dt_pltgot;
Elf_Addr dt_pltrelsz;
const Elf_Sym *dt_symtab;
#ifdef HAVE_JMPREL
RELOC_TYPE *dt_jmprel;
#endif
#if DT_PROCNUM > 0
u_long dt_proc[DT_PROCNUM];
#endif
};
/*
* Local decls.
*/
void _dl_boot_bind(const long, long *, Elf_Dyn *);
void
_dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp)
{
struct boot_dyn dynld; /* Resolver data for the loader */
AuxInfo *auxstack;
long *stack;
int n, argc;
char **argv, **envp;
long loff;
Elf_Addr i;
RELOC_TYPE *rp;
Elf_Ehdr *ehdp;
Elf_Phdr *phdp;
/*
* Scan argument and environment vectors. Find dynamic
* data vector put after them.
*/
stack = (long *)sp;
argc = *stack++;
argv = (char **)stack;
envp = &argv[argc + 1];
stack = (long *)envp;
while (*stack++ != 0L)
;
/*
* Zero out dl_data.
*/
for (n = 0; n <= AUX_entry; n++)
dl_data[n] = 0;
/*
* Dig out auxiliary data set up by exec call. Move all known
* tags to an indexed local table for easy access.
*/
for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
auxstack++) {
if (auxstack->au_id > AUX_entry)
continue;
dl_data[auxstack->au_id] = auxstack->au_v;
}
loff = dl_data[AUX_base]; /* XXX assumes ld.so is linked at 0x0 */
/*
* We need to do 'selfreloc' in case the code weren't
* loaded at the address it was linked to.
*
* Scan the DYNAMIC section for the loader.
* Cache the data for easier access.
*/
_dl_memset(&dynld, 0, sizeof(dynld));
while (dynp->d_tag != DT_NULL) {
/* first the tags that are pointers to be relocated */
if (dynp->d_tag == DT_PLTGOT)
dynld.dt_pltgot = (void *)(dynp->d_un.d_ptr + loff);
else if (dynp->d_tag == DT_SYMTAB)
dynld.dt_symtab = (void *)(dynp->d_un.d_ptr + loff);
else if (dynp->d_tag == RELOC_TAG) /* DT_{RELA,REL} */
dynld.dt_reloc = (void *)(dynp->d_un.d_ptr + loff);
#ifdef HAVE_JMPREL
else if (dynp->d_tag == DT_JMPREL)
dynld.dt_jmprel = (void *)(dynp->d_un.d_ptr + loff);
#endif
/* Now for the tags that are just sizes or counts */
else if (dynp->d_tag == DT_PLTRELSZ)
dynld.dt_pltrelsz = dynp->d_un.d_val;
else if (dynp->d_tag == RELOC_TAG+1) /* DT_{RELA,REL}SZ */
dynld.dt_relocsz = dynp->d_un.d_val;
#if DT_PROCNUM > 0
else if (dynp->d_tag >= DT_LOPROC &&
dynp->d_tag < DT_LOPROC + DT_PROCNUM)
dynld.dt_proc[dynp->d_tag - DT_LOPROC] =
dynp->d_un.d_val;
#endif /* DT_PROCNUM */
dynp++;
}
#ifdef HAVE_JMPREL
rp = dynld.dt_jmprel;
for (i = 0; i < dynld.dt_pltrelsz; i += sizeof *rp) {
Elf_Addr *ra;
const Elf_Sym *sp;
sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info);
if (ELF_R_SYM(rp->r_info) && sp->st_value == 0)
_dl_exit(5);
ra = (Elf_Addr *)(rp->r_offset + loff);
RELOC_JMPREL(rp, sp, ra, loff, dynld.dt_pltgot);
rp++;
}
#endif /* HAVE_JMPREL */
rp = dynld.dt_reloc;
for (i = 0; i < dynld.dt_relocsz; i += sizeof *rp) {
Elf_Addr *ra;
const Elf_Sym *sp;
sp = dynld.dt_symtab + ELF_R_SYM(rp->r_info);
if (ELF_R_SYM(rp->r_info) && sp->st_value == 0)
_dl_exit(6);
ra = (Elf_Addr *)(rp->r_offset + loff);
RELOC_DYN(rp, sp, ra, loff);
rp++;
}
RELOC_GOT(&dynld, loff);
/*
* we have been fully relocated here, so most things no longer
* need the loff adjustment
*/
/*
* No further changes to the PLT and/or GOT are needed so make
* them read-only.
*/
/* do any RWX -> RX fixups for executable PLTs and apply GNU_RELRO */
ehdp = (Elf_Ehdr *)loff;
phdp = (Elf_Phdr *)(loff + ehdp->e_phoff);
for (i = 0; i < ehdp->e_phnum; i++, phdp++) {
switch (phdp->p_type) {
#if defined(__alpha__) || defined(__hppa__) || defined(__powerpc__) || \
defined(__sparc64__)
case PT_LOAD:
if ((phdp->p_flags & (PF_X | PF_W)) != (PF_X | PF_W))
break;
_dl_mprotect((void *)(phdp->p_vaddr + loff),
phdp->p_memsz, PROT_READ);
break;
#endif
case PT_GNU_RELRO:
_dl_mprotect((void *)(phdp->p_vaddr + loff),
phdp->p_memsz, PROT_READ);
break;
}
}
}
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