Commit 281d2d9f authored by Thomas Haller's avatar Thomas Haller

shared: split random and hash utils

"nm-utils/nm-shared-utils.h" shall contain utility function without other
dependencies. It is intended to be used by other projects as-is.

nm_utils_random_bytes() requires getrandom() and a HAVE_GETRANDOM configure
check. That makes it more cumbersome to re-use "nm-shared-utils.h", in
cases where you don't care about nm_utils_random_bytes().

Split nm_utils_random_bytes() out to a separate file.

Same for hash utils, which depend on nm_utils_random_bytes(). Also, hash
utils will eventually be extended to use siphash24.
parent 1766bbea
......@@ -421,7 +421,9 @@ libnm_core_lib_h_priv = \
shared/nm-utils/c-list-util.h \
shared/nm-utils/nm-dedup-multi.h \
shared/nm-utils/nm-enum-utils.h \
shared/nm-utils/nm-hash-utils.h \
shared/nm-utils/nm-shared-utils.h \
shared/nm-utils/nm-random-utils.h \
shared/nm-utils/nm-udev-utils.h \
shared/nm-meta-setting.h \
libnm-core/crypto.h \
......@@ -437,7 +439,9 @@ libnm_core_lib_c_real = \
shared/nm-utils/c-list-util.c \
shared/nm-utils/nm-dedup-multi.c \
shared/nm-utils/nm-enum-utils.c \
shared/nm-utils/nm-hash-utils.c \
shared/nm-utils/nm-shared-utils.c \
shared/nm-utils/nm-random-utils.c \
shared/nm-utils/nm-udev-utils.c \
shared/nm-meta-setting.c \
libnm-core/crypto.c \
......
......@@ -38,6 +38,7 @@
#endif
#include "nm-utils/nm-enum-utils.h"
#include "nm-utils/nm-hash-utils.h"
#include "nm-common-macros.h"
#include "nm-utils-private.h"
#include "nm-setting-private.h"
......
......@@ -23,6 +23,8 @@
#include "nm-dedup-multi.h"
#include "nm-hash-utils.h"
/*****************************************************************************/
typedef struct {
......
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*
* (C) Copyright 2017 Red Hat, Inc.
*/
#include "nm-default.h"
#include "nm-hash-utils.h"
#include "nm-shared-utils.h"
#include "nm-random-utils.h"
/*****************************************************************************/
guint
NM_HASH_INIT (guint seed)
{
static volatile guint global_seed = 0;
guint g, s;
/* we xor @seed with a random @global_seed. This is to make the hashing behavior
* less predictable and harder to exploit collisions. */
g = global_seed;
if (G_UNLIKELY (g == 0)) {
nm_utils_random_bytes (&s, sizeof (s));
if (s == 0)
s = 42;
g_atomic_int_compare_and_exchange ((int *) &global_seed, 0, s);
g = global_seed;
nm_assert (g);
}
return g ^ seed;
}
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*
* (C) Copyright 2017 Red Hat, Inc.
*/
#ifndef __NM_HASH_UTILS_H__
#define __NM_HASH_UTILS_H__
guint NM_HASH_INIT (guint seed);
static inline guint
NM_HASH_COMBINE (guint h, guint val)
{
/* see g_str_hash() for reasons */
return (h << 5) + h + val;
}
static inline guint
NM_HASH_COMBINE_UINT64 (guint h, guint64 val)
{
return NM_HASH_COMBINE (h, (((guint) val) & 0xFFFFFFFFu) + ((guint) (val >> 32)));
}
static inline guint
NM_HASH_POINTER (gconstpointer ptr)
{
/* same as g_direct_hash(), but inline. */
return GPOINTER_TO_UINT (ptr);
}
#endif /* __NM_HASH_UTILS_H__ */
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*
* (C) Copyright 2017 Red Hat, Inc.
*/
#include "nm-default.h"
#include "nm-random-utils.h"
#include <fcntl.h>
#if USE_SYS_RANDOM_H
#include <sys/random.h>
#else
#include <linux/random.h>
#endif
#include "nm-shared-utils.h"
/*****************************************************************************/
/**
* nm_utils_random_bytes:
* @p: the buffer to fill
* @n: the number of bytes to write to @p.
*
* Uses getrandom() or reads /dev/urandom to fill the buffer
* with random data. If all fails, as last fallback it uses
* GRand to fill the buffer with pseudo random numbers.
* The function always succeeds in writing some random numbers
* to the buffer. The return value of FALSE indicates that the
* obtained bytes are probably not of good randomness.
*
* Returns: whether the written bytes are good. If you
* don't require good randomness, you can ignore the return
* value.
*
* Note that if calling getrandom() fails because there is not enough
* entroy (at early boot), the function will read /dev/urandom.
* Which of course, still has low entropy, and cause kernel to log
* a warning.
*/
gboolean
nm_utils_random_bytes (void *p, size_t n)
{
int fd;
int r;
gboolean has_high_quality = TRUE;
gboolean urandom_success;
guint8 *buf = p;
gboolean avoid_urandom = FALSE;
g_return_val_if_fail (p, FALSE);
g_return_val_if_fail (n > 0, FALSE);
#if HAVE_GETRANDOM
{
static gboolean have_syscall = TRUE;
if (have_syscall) {
r = getrandom (buf, n, GRND_NONBLOCK);
if (r > 0) {
if ((size_t) r == n)
return TRUE;
/* no or partial read. There is not enough entropy.
* Fill the rest reading from urandom, and remember that
* some bits are not hight quality. */
nm_assert (r < n);
buf += r;
n -= r;
has_high_quality = FALSE;
/* At this point, we don't want to read /dev/urandom, because
* the entropy pool is low (early boot?), and asking for more
* entropy causes kernel messages to be logged.
*
* We use our fallback via GRand. Note that g_rand_new() also
* tries to seed itself with data from /dev/urandom, but since
* we reuse the instance, it shouldn't matter. */
avoid_urandom = TRUE;
} else {
if (errno == ENOSYS) {
/* no support for getrandom(). We don't know whether
* we urandom will give us good quality. Assume yes. */
have_syscall = FALSE;
} else {
/* unknown error. We'll read urandom below, but we don't have
* high-quality randomness. */
has_high_quality = FALSE;
}
}
}
}
#endif
urandom_success = FALSE;
if (!avoid_urandom) {
fd_open:
fd = open ("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOCTTY);
if (fd < 0) {
r = errno;
if (r == EINTR)
goto fd_open;
} else {
r = nm_utils_fd_read_loop_exact (fd, buf, n, TRUE);
close (fd);
if (r >= 0)
urandom_success = TRUE;
}
}
if (!urandom_success) {
static _nm_thread_local GRand *rand = NULL;
gsize i;
int j;
/* we failed to fill the bytes reading from urandom.
* Fill the bits using GRand pseudo random numbers.
*
* We don't have good quality.
*/
has_high_quality = FALSE;
if (G_UNLIKELY (!rand))
rand = g_rand_new ();
nm_assert (n > 0);
i = 0;
for (;;) {
const union {
guint32 v32;
guint8 v8[4];
} v = {
.v32 = g_rand_int (rand),
};
for (j = 0; j < 4; ) {
buf[i++] = v.v8[j++];
if (i >= n)
goto done;
}
}
done:
;
}
return has_high_quality;
}
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*
* (C) Copyright 2017 Red Hat, Inc.
*/
#ifndef __NM_RANDOM_UTILS_H__
#define __NM_RANDOM_UTILS_H__
gboolean nm_utils_random_bytes (void *p, size_t n);
#endif /* __NM_RANDOM_UTILS_H__ */
......@@ -28,12 +28,6 @@
#include <poll.h>
#include <fcntl.h>
#if USE_SYS_RANDOM_H
#include <sys/random.h>
#else
#include <linux/random.h>
#endif
/*****************************************************************************/
const void *const _NM_PTRARRAY_EMPTY[1] = { NULL };
......@@ -863,29 +857,6 @@ nm_g_object_class_find_property_from_gtype (GType gtype,
/*****************************************************************************/
guint
NM_HASH_INIT (guint seed)
{
static volatile guint global_seed = 0;
guint g, s;
/* we xor @seed with a random @global_seed. This is to make the hashing behavior
* less predictable and harder to exploit collisions. */
g = global_seed;
if (G_UNLIKELY (g == 0)) {
nm_utils_random_bytes (&s, sizeof (s));
if (s == 0)
s = 42;
g_atomic_int_compare_and_exchange ((int *) &global_seed, 0, s);
g = global_seed;
nm_assert (g);
}
return g ^ seed;
}
/*****************************************************************************/
static void
_str_append_escape (GString *s, char ch)
{
......@@ -1118,134 +1089,3 @@ nm_utils_fd_read_loop_exact (int fd, void *buf, size_t nbytes, bool do_poll)
return 0;
}
/*****************************************************************************/
/**
* nm_utils_random_bytes:
* @p: the buffer to fill
* @n: the number of bytes to write to @p.
*
* Uses getrandom() or reads /dev/urandom to fill the buffer
* with random data. If all fails, as last fallback it uses
* GRand to fill the buffer with pseudo random numbers.
* The function always succeeds in writing some random numbers
* to the buffer. The return value of FALSE indicates that the
* obtained bytes are probably not of good randomness.
*
* Returns: whether the written bytes are good. If you
* don't require good randomness, you can ignore the return
* value.
*
* Note that if calling getrandom() fails because there is not enough
* entroy (at early boot), the function will read /dev/urandom.
* Which of course, still has low entropy, and cause kernel to log
* a warning.
*/
gboolean
nm_utils_random_bytes (void *p, size_t n)
{
int fd;
int r;
gboolean has_high_quality = TRUE;
gboolean urandom_success;
guint8 *buf = p;
gboolean avoid_urandom = FALSE;
g_return_val_if_fail (p, FALSE);
g_return_val_if_fail (n > 0, FALSE);
#if HAVE_GETRANDOM
{
static gboolean have_syscall = TRUE;
if (have_syscall) {
r = getrandom (buf, n, GRND_NONBLOCK);
if (r > 0) {
if ((size_t) r == n)
return TRUE;
/* no or partial read. There is not enough entropy.
* Fill the rest reading from urandom, and remember that
* some bits are not hight quality. */
nm_assert (r < n);
buf += r;
n -= r;
has_high_quality = FALSE;
/* At this point, we don't want to read /dev/urandom, because
* the entropy pool is low (early boot?), and asking for more
* entropy causes kernel messages to be logged.
*
* We use our fallback via GRand. Note that g_rand_new() also
* tries to seed itself with data from /dev/urandom, but since
* we reuse the instance, it shouldn't matter. */
avoid_urandom = TRUE;
} else {
if (errno == ENOSYS) {
/* no support for getrandom(). We don't know whether
* we urandom will give us good quality. Assume yes. */
have_syscall = FALSE;
} else {
/* unknown error. We'll read urandom below, but we don't have
* high-quality randomness. */
has_high_quality = FALSE;
}
}
}
}
#endif
urandom_success = FALSE;
if (!avoid_urandom) {
fd_open:
fd = open ("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOCTTY);
if (fd < 0) {
r = errno;
if (r == EINTR)
goto fd_open;
} else {
r = nm_utils_fd_read_loop_exact (fd, buf, n, TRUE);
close (fd);
if (r >= 0)
urandom_success = TRUE;
}
}
if (!urandom_success) {
static _nm_thread_local GRand *rand = NULL;
gsize i;
int j;
/* we failed to fill the bytes reading from urandom.
* Fill the bits using GRand pseudo random numbers.
*
* We don't have good quality.
*/
has_high_quality = FALSE;
if (G_UNLIKELY (!rand))
rand = g_rand_new ();
nm_assert (n > 0);
i = 0;
for (;;) {
const union {
guint32 v32;
guint8 v8[4];
} v = {
.v32 = g_rand_int (rand),
};
for (j = 0; j < 4; ) {
buf[i++] = v.v8[j++];
if (i >= n)
goto done;
}
}
done:
;
}
return has_high_quality;
}
......@@ -378,30 +378,6 @@ GParamSpec *nm_g_object_class_find_property_from_gtype (GType gtype,
/*****************************************************************************/
guint NM_HASH_INIT (guint seed);
static inline guint
NM_HASH_COMBINE (guint h, guint val)
{
/* see g_str_hash() for reasons */
return (h << 5) + h + val;
}
static inline guint
NM_HASH_COMBINE_UINT64 (guint h, guint64 val)
{
return NM_HASH_COMBINE (h, (((guint) val) & 0xFFFFFFFFu) + ((guint) (val >> 32)));
}
static inline guint
NM_HASH_POINTER (gconstpointer ptr)
{
/* same as g_direct_hash(), but inline. */
return GPOINTER_TO_UINT (ptr);
}
/*****************************************************************************/
typedef enum {
NM_UTILS_STR_UTF8_SAFE_FLAG_NONE = 0,
NM_UTILS_STR_UTF8_SAFE_FLAG_ESCAPE_CTRL = 0x0001,
......@@ -430,8 +406,4 @@ int nm_utils_fd_read_loop_exact (int fd, void *buf, size_t nbytes, bool do_poll)
/*****************************************************************************/
gboolean nm_utils_random_bytes (void *p, size_t n);
/*****************************************************************************/
#endif /* __NM_SHARED_UTILS_H__ */
......@@ -32,6 +32,7 @@
#include <linux/rtnetlink.h>
#include "nm-utils/nm-dedup-multi.h"
#include "nm-utils/nm-random-utils.h"
#include "NetworkManagerUtils.h"
#include "nm-utils.h"
......
......@@ -36,6 +36,7 @@
#include <linux/if_infiniband.h>
#include <net/ethernet.h>
#include "nm-utils/nm-random-utils.h"
#include "nm-utils.h"
#include "nm-core-internal.h"
#include "nm-setting-connection.h"
......
......@@ -25,6 +25,8 @@
#include <stdio.h>
#include <arpa/inet.h>
#include "nm-utils/nm-hash-utils.h"
#include "nm-connection.h"
/*****************************************************************************/
......
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