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/* Copyright (c) 2008, 2009, 2010, 2011, 2013, 2016, 2017 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "uuid.h"
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "aes128.h"
#include "entropy.h"
#include "fatal-signal.h"
#include "openvswitch/vlog.h"
#include "ovs-replay.h"
#include "ovs-thread.h"
#include "sha1.h"
#include "timeval.h"
#include "util.h"
VLOG_DEFINE_THIS_MODULE(uuid);
static struct aes128 key;
static uint64_t counter[2];
BUILD_ASSERT_DECL(sizeof counter == 16);
static void do_init(void);
/*
* Initialize the UUID module. Aborts the program with an error message if
* initialization fails (which should never happen on a properly configured
* machine.)
*
* Currently initialization is only needed by uuid_generate(). uuid_generate()
* will automatically call uuid_init() itself, so it's only necessary to call
* this function explicitly if you want to abort the program earlier than the
* first UUID generation in case of failure.
*/
void
uuid_init(void)
{
static pthread_once_t once = PTHREAD_ONCE_INIT;
pthread_once(&once, do_init);
}
/* Record/replay of uuid generation. */
static replay_file_t uuid_replay_file;
static int uuid_replay_seqno;
static void
uuid_replay_file_close(void *aux OVS_UNUSED)
{
ovs_replay_file_close(uuid_replay_file);
}
static void
uuid_replay_file_open(void)
{
int error;
ovs_replay_lock();
error = ovs_replay_file_open("__uuid_generate", &uuid_replay_file,
&uuid_replay_seqno);
ovs_replay_unlock();
if (error) {
VLOG_FATAL("failed to open uuid replay file: %s.",
ovs_strerror(error));
}
fatal_signal_add_hook(uuid_replay_file_close, NULL, NULL, true);
}
static void
uuid_replay_file_read(struct uuid *uuid)
{
int norm_seqno = ovs_replay_normalized_seqno(uuid_replay_seqno);
int retval, len;
ovs_replay_lock();
ovs_assert(norm_seqno == ovs_replay_seqno());
ovs_assert(ovs_replay_seqno_is_read(uuid_replay_seqno));
retval = ovs_replay_read(uuid_replay_file, uuid, sizeof *uuid,
&len, &uuid_replay_seqno, true);
if (retval || len != sizeof *uuid) {
VLOG_FATAL("failed to read from replay file: %s.",
ovs_strerror(retval));
}
ovs_replay_unlock();
}
static void
uuid_replay_file_write(struct uuid *uuid)
{
int retval;
retval = ovs_replay_write(uuid_replay_file, uuid, sizeof *uuid, true);
if (retval) {
VLOG_FATAL("failed to write uuid to replay file: %s.",
ovs_strerror(retval));
}
}
/* Generates a new random UUID in 'uuid'.
*
* We go to some trouble to ensure as best we can that the generated UUID has
* these properties:
*
* - Uniqueness. The random number generator is seeded using both the
* system clock and the system random number generator, plus a few
* other identifiers, which is about as good as we can get in any kind
* of simple way.
*
* - Unpredictability. In some situations it could be bad for an
* adversary to be able to guess the next UUID to be generated with some
* probability of success. This property may or may not be important
* for our purposes, but it is better if we can get it.
*
* To ensure both of these, we start by taking our seed data and passing it
* through SHA-1. We use the result as an AES-128 key. We also generate a
* random 16-byte value[*] which we then use as the counter for CTR mode. To
* generate a UUID in a manner compliant with the above goals, we merely
* increment the counter and encrypt it.
*
* [*] It is not actually important that the initial value of the counter be
* random. AES-128 in counter mode is secure either way.
*/
void
uuid_generate(struct uuid *uuid)
{
static struct ovs_mutex mutex = OVS_MUTEX_INITIALIZER;
enum ovs_replay_state replay_state = ovs_replay_get_state();
uint64_t copy[2];
uuid_init();
if (replay_state == OVS_REPLAY_READ) {
uuid_replay_file_read(uuid);
return;
}
/* Copy out the counter's current value, then increment it. */
ovs_mutex_lock(&mutex);
copy[0] = counter[0];
copy[1] = counter[1];
if (++counter[1] == 0) {
counter[0]++;
}
ovs_mutex_unlock(&mutex);
/* AES output is exactly 16 bytes, so we encrypt directly into 'uuid'. */
aes128_encrypt(&key, copy, uuid);
uuid_set_bits_v4(uuid);
if (replay_state == OVS_REPLAY_WRITE) {
uuid_replay_file_write(uuid);
}
}
struct uuid
uuid_random(void)
{
struct uuid uuid;
uuid_generate(&uuid);
return uuid;
}
void
uuid_set_bits_v4(struct uuid *uuid)
{
/* Set bits to indicate a random UUID. See RFC 4122 section 4.4. */
uuid->parts[2] &= ~0xc0000000;
uuid->parts[2] |= 0x80000000;
uuid->parts[1] &= ~0x0000f000;
uuid->parts[1] |= 0x00004000;
}
/* Sets 'uuid' to all-zero-bits. */
void
uuid_zero(struct uuid *uuid)
{
*uuid = UUID_ZERO;
}
/* Returns true if 'uuid' is all zero, otherwise false. */
bool
uuid_is_zero(const struct uuid *uuid)
{
return (!uuid->parts[0] && !uuid->parts[1]
&& !uuid->parts[2] && !uuid->parts[3]);
}
/* Compares 'a' and 'b'. Returns a negative value if 'a < b', zero if 'a ==
* b', or positive if 'a > b'. The ordering is lexicographical order of the
* conventional way of writing out UUIDs as strings. */
int
uuid_compare_3way(const struct uuid *a, const struct uuid *b)
{
if (a->parts[0] != b->parts[0]) {
return a->parts[0] > b->parts[0] ? 1 : -1;
} else if (a->parts[1] != b->parts[1]) {
return a->parts[1] > b->parts[1] ? 1 : -1;
} else if (a->parts[2] != b->parts[2]) {
return a->parts[2] > b->parts[2] ? 1 : -1;
} else if (a->parts[3] != b->parts[3]) {
return a->parts[3] > b->parts[3] ? 1 : -1;
} else {
return 0;
}
}
/* Attempts to convert string 's' into a UUID in 'uuid'. Returns true if
* successful, which will be the case only if 's' has the exact format
* specified by RFC 4122. Returns false on failure. On failure, 'uuid' will
* be set to all-zero-bits. */
bool
uuid_from_string(struct uuid *uuid, const char *s)
{
if (!uuid_from_string_prefix(uuid, s)) {
return false;
} else if (s[UUID_LEN] != '\0') {
uuid_zero(uuid);
return false;
} else {
return true;
}
}
/* Same as uuid_from_string() but s[UUID_LEN] is not required to be a null byte
* to succeed; that is, 's' need only begin with UUID syntax, not consist
* entirely of it. */
bool
uuid_from_string_prefix(struct uuid *uuid, const char *s)
{
/* 0 1 2 3 */
/* 012345678901234567890123456789012345 */
/* ------------------------------------ */
/* 00000000-1111-1111-2222-222233333333 */
bool ok;
uuid->parts[0] = hexits_value(s, 8, &ok);
if (!ok || s[8] != '-') {
goto error;
}
uuid->parts[1] = hexits_value(s + 9, 4, &ok) << 16;
if (!ok || s[13] != '-') {
goto error;
}
uuid->parts[1] += hexits_value(s + 14, 4, &ok);
if (!ok || s[18] != '-') {
goto error;
}
uuid->parts[2] = hexits_value(s + 19, 4, &ok) << 16;
if (!ok || s[23] != '-') {
goto error;
}
uuid->parts[2] += hexits_value(s + 24, 4, &ok);
if (!ok) {
goto error;
}
uuid->parts[3] = hexits_value(s + 28, 8, &ok);
if (!ok) {
goto error;
}
return true;
error:
uuid_zero(uuid);
return false;
}
/* If 's' is a string representation of a UUID, or the beginning of one,
* returns strlen(s), otherwise 0.
*
* For example:
*
* "123" yields 3
* "xyzzy" yields 0
* "123xyzzy" yields 0
* "e66250bb-9531-491b-b9c3-5385cabb0080" yields 36
* "e66250bb-9531-491b-b9c3-5385cabb0080xyzzy" yields 0
*/
int
uuid_is_partial_string(const char *s)
{
static const char tmpl[UUID_LEN] = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
size_t i;
for (i = 0; i < UUID_LEN; i++) {
if (s[i] == '\0') {
return i;
} else if (tmpl[i] == 'x'
? hexit_value(s[i]) < 0
: s[i] != '-') {
return 0;
}
}
if (s[i] != '\0') {
return 0;
}
return i;
}
/* Compares 'match' to the string representation of 'uuid'. If 'match' equals
* or is a prefix of this string representation, returns strlen(match);
* otherwise, returns 0. */
int
uuid_is_partial_match(const struct uuid *uuid, const char *match)
{
char uuid_s[UUID_LEN + 1];
snprintf(uuid_s, sizeof uuid_s, UUID_FMT, UUID_ARGS(uuid));
size_t match_len = strlen(match);
return !strncmp(uuid_s, match, match_len) ? match_len : 0;
}
static void
sha1_update_int(struct sha1_ctx *sha1_ctx, uintmax_t x)
{
sha1_update(sha1_ctx, &x, sizeof x);
}
static void
do_init(void)
{
uint8_t sha1[SHA1_DIGEST_SIZE];
struct sha1_ctx sha1_ctx;
uint8_t random_seed[16];
struct timeval now;
if (ovs_replay_is_active()) {
uuid_replay_file_open();
}
/* Get seed data. */
get_entropy_or_die(random_seed, sizeof random_seed);
xgettimeofday(&now);
/* Convert seed into key. */
sha1_init(&sha1_ctx);
sha1_update(&sha1_ctx, random_seed, sizeof random_seed);
sha1_update(&sha1_ctx, &now, sizeof now);
sha1_update_int(&sha1_ctx, getpid());
#ifndef _WIN32
sha1_update_int(&sha1_ctx, getppid());
sha1_update_int(&sha1_ctx, getuid());
sha1_update_int(&sha1_ctx, getgid());
#endif
sha1_final(&sha1_ctx, sha1);
/* Generate key. */
BUILD_ASSERT(sizeof sha1 >= 16);
aes128_schedule(&key, sha1);
/* Generate initial counter. */
get_entropy_or_die(counter, sizeof counter);
}
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