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Remove multi-thread support from arc4random.

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Sudo is not multi-threaded so we don't need the added complexity.
This commit is contained in:
Todd C. Miller
2020-01-28 06:41:42 -07:00
parent aa7ea419f0
commit 13cc65038f
4 changed files with 48 additions and 171 deletions
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1
MANIFEST
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@@ -110,7 +110,6 @@ lib/logsrv/protobuf-c.c
lib/util/Makefile.in lib/util/Makefile.in
lib/util/aix.c lib/util/aix.c
lib/util/arc4random.c lib/util/arc4random.c
lib/util/arc4random.h
lib/util/arc4random_uniform.c lib/util/arc4random_uniform.c
lib/util/cfmakeraw.c lib/util/cfmakeraw.c
lib/util/chacha_private.h lib/util/chacha_private.h

8
lib/util/Makefile.in
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@@ -442,12 +442,12 @@ aix.i: $(srcdir)/aix.c $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
aix.plog: aix.i aix.plog: aix.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/aix.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/aix.c --i-file $< --output-file $@
arc4random.lo: $(srcdir)/arc4random.c $(incdir)/sudo_compat.h \ arc4random.lo: $(srcdir)/arc4random.c $(incdir)/sudo_compat.h \
$(incdir)/sudo_rand.h $(srcdir)/arc4random.h \ $(incdir)/sudo_rand.h $(srcdir)/chacha_private.h \
$(srcdir)/chacha_private.h $(top_builddir)/config.h $(top_builddir)/config.h
$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/arc4random.c $(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/arc4random.c
arc4random.i: $(srcdir)/arc4random.c $(incdir)/sudo_compat.h \ arc4random.i: $(srcdir)/arc4random.c $(incdir)/sudo_compat.h \
$(incdir)/sudo_rand.h $(srcdir)/arc4random.h \ $(incdir)/sudo_rand.h $(srcdir)/chacha_private.h \
$(srcdir)/chacha_private.h $(top_builddir)/config.h $(top_builddir)/config.h
$(CC) -E -o $@ $(CPPFLAGS) $< $(CC) -E -o $@ $(CPPFLAGS) $<
arc4random.plog: arc4random.i arc4random.plog: arc4random.i
rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/arc4random.c --i-file $< --output-file $@ rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/arc4random.c --i-file $< --output-file $@

101
lib/util/arc4random.c
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@@ -60,32 +60,26 @@
#define minimum(a, b) ((a) < (b) ? (a) : (b)) #define minimum(a, b) ((a) < (b) ? (a) : (b))
#if defined(__GNUC__) || defined(_MSC_VER) #ifdef __GNUC__
#define inline __inline # define inline __inline
#else /* __GNUC__ || _MSC_VER */ #else /* !__GNUC__ */
#define inline # define inline
#endif /* !__GNUC__ && !_MSC_VER */ #endif /* !__GNUC__ */
/* Sudo isn't multithreaded */
#define _ARC4_LOCK()
#define _ARC4_UNLOCK()
#define KEYSZ 32 #define KEYSZ 32
#define IVSZ 8 #define IVSZ 8
#define BLOCKSZ 64 #define BLOCKSZ 64
#define RSBUFSZ (16*BLOCKSZ) #define RSBUFSZ (16*BLOCKSZ)
static int rs_initialized;
/* Marked MAP_INHERIT_ZERO, so zero'd out in fork children. */ static pid_t rs_stir_pid;
static struct _rs { static chacha_ctx rs; /* chacha context for random keystream */
size_t rs_have; /* valid bytes at end of rs_buf */ static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
size_t rs_count; /* bytes till reseed */ static size_t rs_have; /* valid bytes at end of rs_buf */
} *rs; static size_t rs_count; /* bytes till reseed */
/* Maybe be preserved in fork children, if _rs_allocate() decides. */
static struct _rsx {
chacha_ctx rs_chacha; /* chacha context for random keystream */
unsigned char rs_buf[RSBUFSZ]; /* keystream blocks */
} *rsx;
static inline int _rs_allocate(struct _rs **, struct _rsx **);
static inline void _rs_forkdetect(void);
#include "arc4random.h"
static inline void _rs_rekey(unsigned char *dat, size_t datlen); static inline void _rs_rekey(unsigned char *dat, size_t datlen);
@@ -94,14 +88,8 @@ _rs_init(unsigned char *buf, size_t n)
{ {
if (n < KEYSZ + IVSZ) if (n < KEYSZ + IVSZ)
return; return;
chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
if (rs == NULL) { chacha_ivsetup(&rs, buf + KEYSZ);
if (_rs_allocate(&rs, &rsx) == -1)
abort();
}
chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8, 0);
chacha_ivsetup(&rsx->rs_chacha, buf + KEYSZ);
} }
static void static void
@@ -110,54 +98,54 @@ _rs_stir(void)
unsigned char rnd[KEYSZ + IVSZ]; unsigned char rnd[KEYSZ + IVSZ];
if (getentropy(rnd, sizeof rnd) == -1) if (getentropy(rnd, sizeof rnd) == -1)
_getentropy_fail(); raise(SIGKILL);
if (!rs) if (!rs_initialized) {
rs_initialized = 1;
_rs_init(rnd, sizeof(rnd)); _rs_init(rnd, sizeof(rnd));
else } else
_rs_rekey(rnd, sizeof(rnd)); _rs_rekey(rnd, sizeof(rnd));
memset_s(rnd, sizeof(rnd), 0, sizeof(rnd)); /* discard source seed */ memset_s(rnd, sizeof(rnd), 0, sizeof(rnd)); /* discard source seed */
/* invalidate rs_buf */ /* invalidate rs_buf */
rs->rs_have = 0; rs_have = 0;
memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf)); memset(rs_buf, 0, sizeof(rs_buf));
rs->rs_count = 1600000; rs_count = 1600000;
} }
static inline void static inline void
_rs_stir_if_needed(size_t len) _rs_stir_if_needed(size_t len)
{ {
_rs_forkdetect(); pid_t pid = getpid();
if (!rs || rs->rs_count <= len)
if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
rs_stir_pid = pid;
_rs_stir(); _rs_stir();
if (rs->rs_count <= len) } else
rs->rs_count = 0; rs_count -= len;
else
rs->rs_count -= len;
} }
static inline void static inline void
_rs_rekey(unsigned char *dat, size_t datlen) _rs_rekey(unsigned char *dat, size_t datlen)
{ {
#ifndef KEYSTREAM_ONLY #ifndef KEYSTREAM_ONLY
memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf)); memset(rs_buf, 0, sizeof(rs_buf));
#endif #endif
/* fill rs_buf with the keystream */ /* fill rs_buf with the keystream */
chacha_encrypt_bytes(&rsx->rs_chacha, rsx->rs_buf, chacha_encrypt_bytes(&rs, rs_buf, rs_buf, sizeof(rs_buf));
rsx->rs_buf, sizeof(rsx->rs_buf));
/* mix in optional user provided data */ /* mix in optional user provided data */
if (dat) { if (dat) {
size_t i, m; size_t i, m;
m = minimum(datlen, KEYSZ + IVSZ); m = minimum(datlen, KEYSZ + IVSZ);
for (i = 0; i < m; i++) for (i = 0; i < m; i++)
rsx->rs_buf[i] ^= dat[i]; rs_buf[i] ^= dat[i];
} }
/* immediately reinit for backtracking resistance */ /* immediately reinit for backtracking resistance */
_rs_init(rsx->rs_buf, KEYSZ + IVSZ); _rs_init(rs_buf, KEYSZ + IVSZ);
memset(rsx->rs_buf, 0, KEYSZ + IVSZ); memset(rs_buf, 0, KEYSZ + IVSZ);
rs->rs_have = sizeof(rsx->rs_buf) - KEYSZ - IVSZ; rs_have = sizeof(rs_buf) - KEYSZ - IVSZ;
} }
#ifdef notdef #ifdef notdef
@@ -170,17 +158,16 @@ _rs_random_buf(void *_buf, size_t n)
_rs_stir_if_needed(n); _rs_stir_if_needed(n);
while (n > 0) { while (n > 0) {
if (rs->rs_have > 0) { if (rs_have > 0) {
m = minimum(n, rs->rs_have); m = minimum(n, rs_have);
keystream = rsx->rs_buf + sizeof(rsx->rs_buf) keystream = rs_buf + sizeof(rs_buf) - rs_have;
- rs->rs_have;
memcpy(buf, keystream, m); memcpy(buf, keystream, m);
memset(keystream, 0, m); memset(keystream, 0, m);
buf += m; buf += m;
n -= m; n -= m;
rs->rs_have -= m; rs_have -= m;
} }
if (rs->rs_have == 0) if (rs_have == 0)
_rs_rekey(NULL, 0); _rs_rekey(NULL, 0);
} }
} }
@@ -192,12 +179,12 @@ _rs_random_u32(uint32_t *val)
unsigned char *keystream; unsigned char *keystream;
_rs_stir_if_needed(sizeof(*val)); _rs_stir_if_needed(sizeof(*val));
if (rs->rs_have < sizeof(*val)) if (rs_have < sizeof(*val))
_rs_rekey(NULL, 0); _rs_rekey(NULL, 0);
keystream = rsx->rs_buf + sizeof(rsx->rs_buf) - rs->rs_have; keystream = rs_buf + sizeof(rs_buf) - rs_have;
memcpy(val, keystream, sizeof(*val)); memcpy(val, keystream, sizeof(*val));
memset(keystream, 0, sizeof(*val)); memset(keystream, 0, sizeof(*val));
rs->rs_have -= sizeof(*val); rs_have -= sizeof(*val);
} }
uint32_t uint32_t

109
lib/util/arc4random.h
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@@ -1,109 +0,0 @@
/* $OpenBSD: arc4random.h,v 1.4 2015/01/15 06:57:18 deraadt Exp $ */
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 1996, David Mazieres <dm@uun.org>
* Copyright (c) 2008, Damien Miller <djm@openbsd.org>
* Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
* Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Stub functions for portability.
*/
#include <sys/mman.h>
#include <signal.h>
#ifdef HAVE_PTHREAD_H
#include <pthread.h>
static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
#define _ARC4_LOCK() pthread_mutex_lock(&arc4random_mtx)
#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
#else
#define _ARC4_LOCK()
#define _ARC4_UNLOCK()
#endif /* HAVE_PTHREAD_H */
#ifdef HAVE_PTHREAD_ATFORK
# define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
# else
# define _ARC4_ATFORK(f)
#endif
#if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
# define MAP_ANON MAP_ANONYMOUS
#endif
static inline void
_getentropy_fail(void)
{
raise(SIGKILL);
}
static volatile sig_atomic_t _rs_forked;
#ifdef HAVE_PTHREAD_ATFORK
static inline void
_rs_forkhandler(void)
{
_rs_forked = 1;
}
#endif /* HAVE_PTHREAD_ATFORK */
static int wipeonfork;
static inline void
_rs_forkdetect(void)
{
if (!wipeonfork) {
static pid_t _rs_pid = 0;
pid_t pid = getpid();
if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
_rs_pid = pid;
_rs_forked = 0;
if (rs)
memset(rs, 0, sizeof(*rs));
}
}
}
static inline int
_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
{
if ((*rsp = (void *)mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
return (-1);
if ((*rsxp = (void *)mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
munmap((void *)*rsp, sizeof(**rsp));
*rsp = NULL;
return (-1);
}
#ifdef MADV_WIPEONFORK
if (madvise (*rsp, sizeof(**rsp), MADV_WIPEONFORK) == 0 &&
madvise (*rsxp, sizeof(**rsxp), MADV_WIPEONFORK) == 0) {
wipeonfork = 1;
}
#endif
_ARC4_ATFORK(_rs_forkhandler);
return (0);
}