f8e8a06d23
Push the root seed version to userspace through the VDSO page, if the RANDOM_FENESTRASX algorithm is enabled. Otherwise, there is no functional change. The mechanism can be disabled with debug.fxrng_vdso_enable=0. arc4random(3) obtains a pointer to the root seed version published by the kernel in the shared page at allocation time. Like arc4random(9), it maintains its own per-process copy of the seed version corresponding to the root seed version at the time it last rekeyed. On read requests, the process seed version is compared with the version published in the shared page; if they do not match, arc4random(3) reseeds from the kernel before providing generated output. This change does not implement the FenestrasX concept of PCPU userspace generators seeded from a per-process base generator. That change is left for future discussion/work. Reviewed by: kib (previous version) Approved by: csprng (me -- only touching FXRNG here) Differential Revision: https://reviews.freebsd.org/D22839
379 lines
8.1 KiB
C
379 lines
8.1 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright 2010, 2012 Konstantin Belousov <kib@FreeBSD.ORG>.
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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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*
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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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <elf.h>
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#include <errno.h>
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#include <link.h>
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#include <pthread.h>
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#include <string.h>
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#include <sys/auxv.h>
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#include "un-namespace.h"
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#include "libc_private.h"
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extern char **environ;
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extern int _DYNAMIC;
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#pragma weak _DYNAMIC
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void *__elf_aux_vector;
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static pthread_once_t aux_vector_once = PTHREAD_ONCE_INIT;
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static void
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init_aux_vector_once(void)
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{
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Elf_Addr *sp;
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sp = (Elf_Addr *)environ;
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while (*sp++ != 0)
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;
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__elf_aux_vector = (Elf_Auxinfo *)sp;
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}
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void
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__init_elf_aux_vector(void)
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{
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if (&_DYNAMIC != NULL)
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return;
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_once(&aux_vector_once, init_aux_vector_once);
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}
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static pthread_once_t aux_once = PTHREAD_ONCE_INIT;
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static int pagesize, osreldate, canary_len, ncpus, pagesizes_len, bsdflags;
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static int hwcap_present, hwcap2_present;
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static char *canary, *pagesizes, *execpath;
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static void *ps_strings, *timekeep;
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static u_long hwcap, hwcap2;
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static void *fxrng_seed_version;
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#ifdef __powerpc__
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static int powerpc_new_auxv_format = 0;
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static void _init_aux_powerpc_fixup(void);
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int _powerpc_elf_aux_info(int, void *, int);
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#endif
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static void
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init_aux(void)
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{
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Elf_Auxinfo *aux;
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for (aux = __elf_aux_vector; aux->a_type != AT_NULL; aux++) {
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switch (aux->a_type) {
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case AT_BSDFLAGS:
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bsdflags = aux->a_un.a_val;
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break;
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case AT_CANARY:
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canary = (char *)(aux->a_un.a_ptr);
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break;
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case AT_CANARYLEN:
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canary_len = aux->a_un.a_val;
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break;
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case AT_EXECPATH:
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execpath = (char *)(aux->a_un.a_ptr);
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break;
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case AT_HWCAP:
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hwcap_present = 1;
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hwcap = (u_long)(aux->a_un.a_val);
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break;
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case AT_HWCAP2:
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hwcap2_present = 1;
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hwcap2 = (u_long)(aux->a_un.a_val);
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break;
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case AT_PAGESIZES:
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pagesizes = (char *)(aux->a_un.a_ptr);
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break;
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case AT_PAGESIZESLEN:
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pagesizes_len = aux->a_un.a_val;
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break;
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case AT_PAGESZ:
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pagesize = aux->a_un.a_val;
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break;
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case AT_OSRELDATE:
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osreldate = aux->a_un.a_val;
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break;
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case AT_NCPUS:
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ncpus = aux->a_un.a_val;
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break;
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case AT_TIMEKEEP:
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timekeep = aux->a_un.a_ptr;
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break;
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case AT_PS_STRINGS:
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ps_strings = aux->a_un.a_ptr;
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break;
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case AT_FXRNG:
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fxrng_seed_version = aux->a_un.a_ptr;
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break;
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#ifdef __powerpc__
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/*
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* Since AT_STACKPROT is always set, and the common
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* value 23 is mutually exclusive with the legacy powerpc
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* value 21, the existence of AT_STACKPROT proves we are
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* on the common format.
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*/
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case AT_STACKPROT: /* 23 */
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powerpc_new_auxv_format = 1;
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break;
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#endif
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}
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}
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#ifdef __powerpc__
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if (!powerpc_new_auxv_format)
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_init_aux_powerpc_fixup();
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#endif
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}
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#ifdef __powerpc__
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static void
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_init_aux_powerpc_fixup(void)
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{
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Elf_Auxinfo *aux;
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/*
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* Before 1300070, PowerPC platforms had nonstandard numbering for
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* the aux vector. When running old binaries, the kernel will pass
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* the vector using the old numbering. Reload affected variables.
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*/
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for (aux = __elf_aux_vector; aux->a_type != AT_NULL; aux++) {
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switch (aux->a_type) {
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case AT_OLD_CANARY:
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canary = (char *)(aux->a_un.a_ptr);
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break;
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case AT_OLD_CANARYLEN:
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canary_len = aux->a_un.a_val;
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break;
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case AT_OLD_EXECPATH:
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execpath = (char *)(aux->a_un.a_ptr);
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break;
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case AT_OLD_PAGESIZES:
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pagesizes = (char *)(aux->a_un.a_ptr);
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break;
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case AT_OLD_PAGESIZESLEN:
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pagesizes_len = aux->a_un.a_val;
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break;
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case AT_OLD_OSRELDATE:
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osreldate = aux->a_un.a_val;
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break;
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case AT_OLD_NCPUS:
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ncpus = aux->a_un.a_val;
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break;
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}
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}
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}
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int
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_powerpc_elf_aux_info(int aux, void *buf, int buflen)
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{
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/*
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* If we are in the old auxv format, we need to translate the aux
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* parameter of elf_aux_info() calls into the common auxv format.
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* Internal libc calls always use the common format, and they
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* directly call _elf_aux_info instead of using the weak symbol.
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*/
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if (!powerpc_new_auxv_format) {
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switch (aux) {
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case AT_OLD_EXECPATH:
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aux = AT_EXECPATH;
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break;
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case AT_OLD_CANARY:
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aux = AT_CANARY;
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break;
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case AT_OLD_CANARYLEN:
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aux = AT_CANARYLEN;
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break;
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case AT_OLD_OSRELDATE:
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aux = AT_OSRELDATE;
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break;
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case AT_OLD_NCPUS:
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aux = AT_NCPUS;
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break;
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case AT_OLD_PAGESIZES:
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aux = AT_PAGESIZES;
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break;
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case AT_OLD_PAGESIZESLEN:
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aux = AT_PAGESIZESLEN;
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break;
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case AT_OLD_STACKPROT:
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aux = AT_STACKPROT;
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break;
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}
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}
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return _elf_aux_info(aux, buf, buflen);
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}
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__weak_reference(_powerpc_elf_aux_info, elf_aux_info);
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#else
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__weak_reference(_elf_aux_info, elf_aux_info);
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#endif
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int
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_elf_aux_info(int aux, void *buf, int buflen)
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{
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int res;
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__init_elf_aux_vector();
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if (__elf_aux_vector == NULL)
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return (ENOSYS);
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_once(&aux_once, init_aux);
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if (buflen < 0)
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return (EINVAL);
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switch (aux) {
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case AT_CANARY:
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if (canary != NULL && canary_len >= buflen) {
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memcpy(buf, canary, buflen);
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memset(canary, 0, canary_len);
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canary = NULL;
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res = 0;
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} else
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res = ENOENT;
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break;
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case AT_EXECPATH:
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if (execpath == NULL)
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res = ENOENT;
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else if (buf == NULL)
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res = EINVAL;
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else {
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if (strlcpy(buf, execpath, buflen) >=
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(unsigned int)buflen)
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res = EINVAL;
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else
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res = 0;
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}
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break;
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case AT_HWCAP:
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if (hwcap_present && buflen == sizeof(u_long)) {
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*(u_long *)buf = hwcap;
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res = 0;
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} else
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res = ENOENT;
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break;
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case AT_HWCAP2:
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if (hwcap2_present && buflen == sizeof(u_long)) {
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*(u_long *)buf = hwcap2;
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res = 0;
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} else
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res = ENOENT;
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break;
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case AT_PAGESIZES:
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if (pagesizes != NULL && pagesizes_len >= buflen) {
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memcpy(buf, pagesizes, buflen);
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res = 0;
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} else
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res = ENOENT;
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break;
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case AT_PAGESZ:
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if (buflen == sizeof(int)) {
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if (pagesize != 0) {
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*(int *)buf = pagesize;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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case AT_OSRELDATE:
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if (buflen == sizeof(int)) {
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if (osreldate != 0) {
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*(int *)buf = osreldate;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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case AT_NCPUS:
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if (buflen == sizeof(int)) {
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if (ncpus != 0) {
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*(int *)buf = ncpus;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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case AT_TIMEKEEP:
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if (buflen == sizeof(void *)) {
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if (timekeep != NULL) {
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*(void **)buf = timekeep;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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case AT_BSDFLAGS:
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if (buflen == sizeof(int)) {
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*(int *)buf = bsdflags;
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res = 0;
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} else
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res = EINVAL;
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break;
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case AT_PS_STRINGS:
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if (buflen == sizeof(void *)) {
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if (ps_strings != NULL) {
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*(void **)buf = ps_strings;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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case AT_FXRNG:
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if (buflen == sizeof(void *)) {
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if (fxrng_seed_version != NULL) {
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*(void **)buf = fxrng_seed_version;
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res = 0;
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} else
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res = ENOENT;
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} else
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res = EINVAL;
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break;
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default:
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res = ENOENT;
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break;
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}
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return (res);
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}
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