OpenBSD-4.6/libexec/ld.so/i386/rtld_machine.c
/* $OpenBSD: rtld_machine.c,v 1.23 2008/04/09 21:45:26 kurt Exp $ */
/*
* Copyright (c) 2002 Dale Rahn
* Copyright (c) 2001 Niklas Hallqvist
* Copyright (c) 2001 Artur Grabowski
*
* 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.
*/
/*-
* Copyright (c) 2000 Eduardo Horvath.
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Paul Kranenburg.
*
* 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 the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
#define _DYN_LOADER
#include <sys/types.h>
#include <sys/cdefs.h>
#include <sys/mman.h>
#include <nlist.h>
#include <link.h>
#include <signal.h>
#include "syscall.h"
#include "archdep.h"
#include "resolve.h"
/*
* The following table holds for each relocation type:
* - the width in bits of the memory location the relocation
* applies to (not currently used)
* - the number of bits the relocation value must be shifted to the
* right (i.e. discard least significant bits) to fit into
* the appropriate field in the instruction word.
* - flags indicating whether
* * the relocation involves a symbol
* * the relocation is relative to the current position
* * the relocation is for a GOT entry
* * the relocation is relative to the load address
*
*/
#define _RF_S 0x80000000 /* Resolve symbol */
#define _RF_A 0x40000000 /* Use addend */
#define _RF_P 0x20000000 /* Location relative */
#define _RF_G 0x10000000 /* GOT offset */
#define _RF_B 0x08000000 /* Load address relative */
#define _RF_U 0x04000000 /* Unaligned */
#define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */
#define _RF_RS(s) ((s) & 0xff) /* right shift */
static int reloc_target_flags[] = {
0, /* NONE */
_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32*/
_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC32 */
_RF_G| _RF_SZ(32) | _RF_RS(00), /* GOT32 */
_RF_A| _RF_SZ(32) | _RF_RS(0), /* PLT32 */
_RF_S| _RF_SZ(32) | _RF_RS(0), /* COPY */
_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */
_RF_S| _RF_SZ(32) | _RF_RS(0), /* JUMP_SLOT */
_RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */
0, /* GOTOFF XXX */
0, /* GOTPC XXX */
0, /* DUMMY 11 */
0, /* DUMMY 12 */
0, /* DUMMY 13 */
0, /* DUMMY 14 */
0, /* DUMMY 15 */
0, /* DUMMY 16 */
0, /* DUMMY 17 */
0, /* DUMMY 18 */
0, /* DUMMY 19 */
_RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */
_RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* PC_16 */
_RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */
_RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* RELOC_PC8 */
};
#define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0)
#define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0)
#define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0)
#define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0)
#define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0)
#define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff)
#define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff)
static long reloc_target_bitmask[] = {
#define _BM(x) (~(-(1ULL << (x))))
0, /* NONE */
_BM(32), /* RELOC_32*/
_BM(32), /* PC32 */
_BM(32), /* GOT32 */
_BM(32), /* PLT32 */
0, /* COPY */
_BM(32), /* GLOB_DAT */
_BM(32), /* JUMP_SLOT */
_BM(32), /* RELATIVE */
0, /* GOTOFF XXX */
0, /* GOTPC XXX */
0, /* DUMMY 11 */
0, /* DUMMY 12 */
0, /* DUMMY 13 */
0, /* DUMMY 14 */
0, /* DUMMY 15 */
0, /* DUMMY 16 */
0, /* DUMMY 17 */
0, /* DUMMY 18 */
0, /* DUMMY 19 */
_BM(16), /* RELOC_16 */
_BM(8), /* PC_16 */
_BM(8), /* RELOC_8 */
_BM(8), /* RELOC_PC8 */
#undef _BM
};
#define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t])
void _dl_reloc_plt(Elf_Addr *where, Elf_Addr value);
int
_dl_md_reloc(elf_object_t *object, int rel, int relsz)
{
long i;
long numrel;
int fails = 0;
Elf_Addr loff;
Elf_Rel *rels;
struct load_list *llist;
loff = object->obj_base;
numrel = object->Dyn.info[relsz] / sizeof(Elf32_Rel);
rels = (Elf32_Rel *)(object->Dyn.info[rel]);
if (rels == NULL)
return(0);
/*
* unprotect some segments if we need it.
*/
if ((object->dyn.textrel == 1) && (rel == DT_REL || rel == DT_RELA)) {
for (llist = object->load_list; llist != NULL; llist = llist->next) {
if (!(llist->prot & PROT_WRITE))
_dl_mprotect(llist->start, llist->size,
llist->prot|PROT_WRITE);
}
}
for (i = 0; i < numrel; i++, rels++) {
Elf_Addr *where, value, ooff, mask;
Elf_Word type;
const Elf_Sym *sym, *this;
const char *symn;
type = ELF_R_TYPE(rels->r_info);
if (type == R_TYPE(NONE))
continue;
if (type == R_TYPE(JUMP_SLOT) && rel != DT_JMPREL)
continue;
where = (Elf_Addr *)(rels->r_offset + loff);
if (RELOC_USE_ADDEND(type))
value = *where & RELOC_VALUE_BITMASK(type);
else
value = 0;
sym = NULL;
symn = NULL;
if (RELOC_RESOLVE_SYMBOL(type)) {
sym = object->dyn.symtab;
sym += ELF_R_SYM(rels->r_info);
symn = object->dyn.strtab + sym->st_name;
if (sym->st_shndx != SHN_UNDEF &&
ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
value += loff;
} else {
this = NULL;
ooff = _dl_find_symbol_bysym(object,
ELF_R_SYM(rels->r_info), &this,
SYM_SEARCH_ALL|SYM_WARNNOTFOUND|
((type == R_TYPE(JUMP_SLOT))?
SYM_PLT:SYM_NOTPLT),
sym, NULL);
if (this == NULL) {
resolve_failed:
if (ELF_ST_BIND(sym->st_info) !=
STB_WEAK)
fails++;
continue;
}
value += (Elf_Addr)(ooff + this->st_value);
}
}
if (type == R_TYPE(JUMP_SLOT)) {
_dl_reloc_plt((Elf_Word *)where, value);
continue;
}
if (type == R_TYPE(COPY)) {
void *dstaddr = where;
const void *srcaddr;
const Elf_Sym *dstsym = sym, *srcsym = NULL;
size_t size = dstsym->st_size;
Elf_Addr soff;
soff = _dl_find_symbol(symn, &srcsym,
SYM_SEARCH_OTHER|SYM_WARNNOTFOUND|
((type == R_TYPE(JUMP_SLOT)) ? SYM_PLT:SYM_NOTPLT),
sym, object, NULL);
if (srcsym == NULL)
goto resolve_failed;
srcaddr = (void *)(soff + srcsym->st_value);
_dl_bcopy(srcaddr, dstaddr, size);
continue;
}
if (RELOC_PC_RELATIVE(type))
value -= (Elf_Addr)where;
if (RELOC_BASE_RELATIVE(type))
value += loff;
mask = RELOC_VALUE_BITMASK(type);
value >>= RELOC_VALUE_RIGHTSHIFT(type);
value &= mask;
if (RELOC_UNALIGNED(type)) {
/* Handle unaligned relocations. */
Elf_Addr tmp = 0;
char *ptr = (char *)where;
int i, size = RELOC_TARGET_SIZE(type)/8;
/* Read it in one byte at a time. */
for (i=0; i<size; i++)
tmp = (tmp << 8) | ptr[i];
tmp &= ~mask;
tmp |= value;
/* Write it back out. */
for (i=0; i<size; i++)
ptr[i] = ((tmp >> (8*i)) & 0xff);
} else if (RELOC_TARGET_SIZE(type) > 32) {
*where &= ~mask;
*where |= value;
} else {
Elf32_Addr *where32 = (Elf32_Addr *)where;
*where32 &= ~mask;
*where32 |= value;
}
}
/* reprotect the unprotected segments */
if ((object->dyn.textrel == 1) && (rel == DT_REL || rel == DT_RELA)) {
for (llist = object->load_list; llist != NULL; llist = llist->next) {
if (!(llist->prot & PROT_WRITE))
_dl_mprotect(llist->start, llist->size,
llist->prot);
}
}
return (fails);
}
#if 0
struct jmpslot {
u_short opcode;
u_short addr[2];
u_short reloc_index;
#define JMPSLOT_RELOC_MASK 0xffff
};
#define JUMP 0xe990 /* NOP + JMP opcode */
#endif
void
_dl_reloc_plt(Elf_Addr *where, Elf_Addr value)
{
*where = value;
}
/*
* Resolve a symbol at run-time.
*/
Elf_Addr
_dl_bind(elf_object_t *object, int index)
{
Elf_Rel *rel;
Elf_Word *addr;
const Elf_Sym *sym, *this;
const char *symn;
Elf_Addr ooff;
sigset_t omask, nmask;
rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]);
rel += index/sizeof(Elf_Rel);
sym = object->dyn.symtab;
sym += ELF_R_SYM(rel->r_info);
symn = object->dyn.strtab + sym->st_name;
addr = (Elf_Word *)(object->obj_base + rel->r_offset);
this = NULL;
ooff = _dl_find_symbol(symn, &this,
SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, sym, object, NULL);
if (this == NULL) {
_dl_printf("lazy binding failed!\n");
*((int *)0) = 0; /* XXX */
}
/* if GOT is protected, allow the write */
if (object->got_size != 0) {
sigfillset(&nmask);
_dl_sigprocmask(SIG_BLOCK, &nmask, &omask);
_dl_thread_bind_lock(0);
_dl_mprotect((void*)object->got_start, object->got_size,
PROT_READ|PROT_WRITE);
}
_dl_reloc_plt(addr, ooff + this->st_value);
/* put the GOT back to RO */
if (object->got_size != 0) {
_dl_mprotect((void*)object->got_start, object->got_size,
PROT_READ);
_dl_thread_bind_lock(1);
_dl_sigprocmask(SIG_SETMASK, &omask, NULL);
}
return((Elf_Addr)ooff + this->st_value);
}
int
_dl_md_reloc_got(elf_object_t *object, int lazy)
{
extern void _dl_bind_start(void); /* XXX */
int fails = 0;
Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT];
int i, num;
Elf_Rel *rel;
struct load_list *llist;
Elf_Addr ooff;
const Elf_Sym *this;
if (pltgot == NULL)
return (0); /* it is possible to have no PLT/GOT relocations */
pltgot[1] = (Elf_Addr)object;
pltgot[2] = (Elf_Addr)&_dl_bind_start;
if (object->Dyn.info[DT_PLTREL] != DT_REL)
return (0);
object->got_addr = NULL;
object->got_size = 0;
this = NULL;
ooff = _dl_find_symbol("__got_start", &this,
SYM_SEARCH_OBJ|SYM_NOWARNNOTFOUND|SYM_PLT, NULL, object, NULL);
if (this != NULL)
object->got_addr = ooff + this->st_value;
this = NULL;
ooff = _dl_find_symbol("__got_end", &this,
SYM_SEARCH_OBJ|SYM_NOWARNNOTFOUND|SYM_PLT, NULL, object, NULL);
if (this != NULL)
object->got_size = ooff + this->st_value - object->got_addr;
if (object->got_addr == NULL)
object->got_start = NULL;
else {
object->got_start = ELF_TRUNC(object->got_addr, _dl_pagesz);
object->got_size += object->got_addr - object->got_start;
object->got_size = ELF_ROUND(object->got_size, _dl_pagesz);
}
if (!lazy) {
fails = _dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ);
} else {
rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]);
num = (object->Dyn.info[DT_PLTRELSZ]);
for (llist = object->load_list; llist != NULL;
llist = llist->next) {
if (!(llist->prot & PROT_WRITE))
_dl_mprotect(llist->start, llist->size,
llist->prot|PROT_WRITE);
}
for (i = 0; i < num/sizeof(Elf_Rel); i++, rel++) {
Elf_Addr *where;
where = (Elf_Addr *)(rel->r_offset + object->obj_base);
*where += object->obj_base;
}
for (llist = object->load_list; llist != NULL;
llist = llist->next) {
if (!(llist->prot & PROT_WRITE))
_dl_mprotect(llist->start, llist->size,
llist->prot);
}
}
/* PLT is already RO on i386, no point in mprotecting it, just GOT */
if (object->got_size != 0)
_dl_mprotect((void*)object->got_start, object->got_size,
PROT_READ);
return (fails);
}