HardenedBSD/lib/libsys/auxv.c
Konstantin Belousov 2f4cbf459d libsys auxv.c: add fences needed to ensure that flag works
Noted by:	jrtc27
Sponsored by:	The FreeBSD Foundation
2024-02-21 16:18:10 +02:00

421 lines
9.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright 2010, 2012 Konstantin Belousov <kib@FreeBSD.ORG>.
* 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.
*
* 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.
*
*/
#include "namespace.h"
#include <elf.h>
#include <errno.h>
#include <link.h>
#include <pthread.h>
#include <stdbool.h>
#include <string.h>
#include <sys/auxv.h>
#include "un-namespace.h"
#include "libc_private.h"
#include <machine/atomic.h>
extern int _DYNAMIC;
#pragma weak _DYNAMIC
void *__elf_aux_vector;
#ifndef PIC
static pthread_once_t aux_vector_once = PTHREAD_ONCE_INIT;
static void
init_aux_vector_once(void)
{
Elf_Addr *sp;
sp = (Elf_Addr *)environ;
while (*sp++ != 0)
;
__elf_aux_vector = (Elf_Auxinfo *)sp;
}
void
__init_elf_aux_vector(void)
{
if (&_DYNAMIC != NULL)
return;
_once(&aux_vector_once, init_aux_vector_once);
}
#endif
static int aux_once;
static int pagesize, osreldate, canary_len, ncpus, pagesizes_len, bsdflags;
static int hwcap_present, hwcap2_present;
static char *canary, *pagesizes, *execpath;
static void *ps_strings, *timekeep;
static u_long hwcap, hwcap2;
static void *fxrng_seed_version;
static u_long usrstackbase, usrstacklim;
#ifdef __powerpc__
static int powerpc_new_auxv_format = 0;
static void _init_aux_powerpc_fixup(void);
int _powerpc_elf_aux_info(int, void *, int);
#endif
/*
* This function might be called and actual body executed more than
* once in multithreading environment. Due to this, it is and must
* continue to be idempotent. All stores are atomic (no store
* tearing), because we only assign to int/long/ptr.
*/
static void
init_aux(void)
{
Elf_Auxinfo *aux;
if (atomic_load_acq_int(&aux_once))
return;
for (aux = __elf_aux_vector; aux->a_type != AT_NULL; aux++) {
switch (aux->a_type) {
case AT_BSDFLAGS:
bsdflags = aux->a_un.a_val;
break;
case AT_CANARY:
canary = (char *)(aux->a_un.a_ptr);
break;
case AT_CANARYLEN:
canary_len = aux->a_un.a_val;
break;
case AT_EXECPATH:
execpath = (char *)(aux->a_un.a_ptr);
break;
case AT_HWCAP:
hwcap_present = 1;
hwcap = (u_long)(aux->a_un.a_val);
break;
case AT_HWCAP2:
hwcap2_present = 1;
hwcap2 = (u_long)(aux->a_un.a_val);
break;
case AT_PAGESIZES:
pagesizes = (char *)(aux->a_un.a_ptr);
break;
case AT_PAGESIZESLEN:
pagesizes_len = aux->a_un.a_val;
break;
case AT_PAGESZ:
pagesize = aux->a_un.a_val;
break;
case AT_OSRELDATE:
osreldate = aux->a_un.a_val;
break;
case AT_NCPUS:
ncpus = aux->a_un.a_val;
break;
case AT_TIMEKEEP:
timekeep = aux->a_un.a_ptr;
break;
case AT_PS_STRINGS:
ps_strings = aux->a_un.a_ptr;
break;
case AT_FXRNG:
fxrng_seed_version = aux->a_un.a_ptr;
break;
case AT_USRSTACKBASE:
usrstackbase = aux->a_un.a_val;
break;
case AT_USRSTACKLIM:
usrstacklim = aux->a_un.a_val;
break;
#ifdef __powerpc__
/*
* Since AT_STACKPROT is always set, and the common
* value 23 is mutually exclusive with the legacy powerpc
* value 21, the existence of AT_STACKPROT proves we are
* on the common format.
*/
case AT_STACKPROT: /* 23 */
powerpc_new_auxv_format = 1;
break;
#endif
}
}
#ifdef __powerpc__
if (!powerpc_new_auxv_format)
_init_aux_powerpc_fixup();
#endif
atomic_store_rel_int(&aux_once, 1);
}
#ifdef __powerpc__
static void
_init_aux_powerpc_fixup(void)
{
Elf_Auxinfo *aux;
/*
* Before 1300070, PowerPC platforms had nonstandard numbering for
* the aux vector. When running old binaries, the kernel will pass
* the vector using the old numbering. Reload affected variables.
*/
for (aux = __elf_aux_vector; aux->a_type != AT_NULL; aux++) {
switch (aux->a_type) {
case AT_OLD_CANARY:
canary = (char *)(aux->a_un.a_ptr);
break;
case AT_OLD_CANARYLEN:
canary_len = aux->a_un.a_val;
break;
case AT_OLD_EXECPATH:
execpath = (char *)(aux->a_un.a_ptr);
break;
case AT_OLD_PAGESIZES:
pagesizes = (char *)(aux->a_un.a_ptr);
break;
case AT_OLD_PAGESIZESLEN:
pagesizes_len = aux->a_un.a_val;
break;
case AT_OLD_OSRELDATE:
osreldate = aux->a_un.a_val;
break;
case AT_OLD_NCPUS:
ncpus = aux->a_un.a_val;
break;
}
}
}
int
_powerpc_elf_aux_info(int aux, void *buf, int buflen)
{
/*
* If we are in the old auxv format, we need to translate the aux
* parameter of elf_aux_info() calls into the common auxv format.
* Internal libc calls always use the common format, and they
* directly call _elf_aux_info instead of using the weak symbol.
*/
if (!powerpc_new_auxv_format) {
switch (aux) {
case AT_OLD_EXECPATH:
aux = AT_EXECPATH;
break;
case AT_OLD_CANARY:
aux = AT_CANARY;
break;
case AT_OLD_CANARYLEN:
aux = AT_CANARYLEN;
break;
case AT_OLD_OSRELDATE:
aux = AT_OSRELDATE;
break;
case AT_OLD_NCPUS:
aux = AT_NCPUS;
break;
case AT_OLD_PAGESIZES:
aux = AT_PAGESIZES;
break;
case AT_OLD_PAGESIZESLEN:
aux = AT_PAGESIZESLEN;
break;
case AT_OLD_STACKPROT:
aux = AT_STACKPROT;
break;
}
}
return _elf_aux_info(aux, buf, buflen);
}
__weak_reference(_powerpc_elf_aux_info, elf_aux_info);
#else
__weak_reference(_elf_aux_info, elf_aux_info);
#endif
int
_elf_aux_info(int aux, void *buf, int buflen)
{
int res;
#ifndef PIC
__init_elf_aux_vector();
#endif
if (__elf_aux_vector == NULL)
return (ENOSYS);
init_aux(); /* idempotent */
if (buflen < 0)
return (EINVAL);
switch (aux) {
case AT_CANARY:
if (canary != NULL && canary_len >= buflen) {
memcpy(buf, canary, buflen);
memset(canary, 0, canary_len);
canary = NULL;
res = 0;
} else
res = ENOENT;
break;
case AT_EXECPATH:
if (execpath == NULL)
res = ENOENT;
else if (buf == NULL)
res = EINVAL;
else {
if (strlcpy(buf, execpath, buflen) >=
(unsigned int)buflen)
res = EINVAL;
else
res = 0;
}
break;
case AT_HWCAP:
if (hwcap_present && buflen == sizeof(u_long)) {
*(u_long *)buf = hwcap;
res = 0;
} else
res = ENOENT;
break;
case AT_HWCAP2:
if (hwcap2_present && buflen == sizeof(u_long)) {
*(u_long *)buf = hwcap2;
res = 0;
} else
res = ENOENT;
break;
case AT_PAGESIZES:
if (pagesizes != NULL && pagesizes_len >= buflen) {
memcpy(buf, pagesizes, buflen);
res = 0;
} else
res = ENOENT;
break;
case AT_PAGESZ:
if (buflen == sizeof(int)) {
if (pagesize != 0) {
*(int *)buf = pagesize;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_OSRELDATE:
if (buflen == sizeof(int)) {
if (osreldate != 0) {
*(int *)buf = osreldate;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_NCPUS:
if (buflen == sizeof(int)) {
if (ncpus != 0) {
*(int *)buf = ncpus;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_TIMEKEEP:
if (buflen == sizeof(void *)) {
if (timekeep != NULL) {
*(void **)buf = timekeep;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_BSDFLAGS:
if (buflen == sizeof(int)) {
*(int *)buf = bsdflags;
res = 0;
} else
res = EINVAL;
break;
case AT_PS_STRINGS:
if (buflen == sizeof(void *)) {
if (ps_strings != NULL) {
*(void **)buf = ps_strings;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_FXRNG:
if (buflen == sizeof(void *)) {
if (fxrng_seed_version != NULL) {
*(void **)buf = fxrng_seed_version;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_USRSTACKBASE:
if (buflen == sizeof(u_long)) {
if (usrstackbase != 0) {
*(u_long *)buf = usrstackbase;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
case AT_USRSTACKLIM:
if (buflen == sizeof(u_long)) {
if (usrstacklim != 0) {
*(u_long *)buf = usrstacklim;
res = 0;
} else
res = ENOENT;
} else
res = EINVAL;
break;
default:
res = ENOENT;
break;
}
return (res);
}