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refactor: re-implement shared key cache in separate file

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The exisiting implementation is not clearly documented and used by
multiple modules.
This commit is contained in:
sudden6 2022-05-23 00:38:40 +02:00
parent 2246517c3e
commit 8c7d30475f
No known key found for this signature in database
GPG Key ID: 279509B499E032B9
14 changed files with 364 additions and 154 deletions
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2
CMakeLists.txt
View File

@ -284,6 +284,8 @@ set(toxcore_SOURCES
toxcore/ping_array.h
toxcore/ping.c
toxcore/ping.h
toxcore/shared_key_cache.c
toxcore/shared_key_cache.h
toxcore/state.c
toxcore/state.h
toxcore/TCP_client.c

2
other/bootstrap_daemon/docker/tox-bootstrapd.sha256
View File

@ -1 +1 @@
b2bee729be40b0a0d8a4c6f0e2a527854d9a9d37712b73b915d7470bc91f5e6a /usr/local/bin/tox-bootstrapd
769233afaac07be03c094411e6ec8f031bde41beae475c74e154e51e51e9168b /usr/local/bin/tox-bootstrapd

22
toxcore/BUILD.bazel
View File

@ -180,6 +180,24 @@ cc_test(
],
)
cc_library(
name = "shared_key_cache",
srcs = ["shared_key_cache.c"],
hdrs = ["shared_key_cache.h"],
visibility = [
"//c-toxcore/auto_tests:__pkg__",
"//c-toxcore/other:__pkg__",
"//c-toxcore/other/bootstrap_daemon:__pkg__",
"//c-toxcore/testing:__pkg__",
"//c-toxcore/toxav:__pkg__",
],
deps = [
":ccompat",
":crypto_core",
":mono_time",
],
)
cc_library(
name = "network",
srcs = ["network.c"],
@ -289,6 +307,7 @@ cc_library(
":mono_time",
":network",
":ping_array",
":shared_key_cache",
":state",
":util",
],
@ -326,6 +345,7 @@ cc_library(
":ccompat",
":crypto_core",
":mono_time",
":shared_key_cache",
":util",
],
)
@ -366,6 +386,7 @@ cc_library(
":LAN_discovery",
":ccompat",
":forwarding",
":shared_key_cache",
":timed_auth",
":util",
],
@ -480,6 +501,7 @@ cc_library(
":ccompat",
":mono_time",
":onion",
":shared_key_cache",
":timed_auth",
":util",
],

105
toxcore/DHT.c
View File

@ -18,6 +18,7 @@
#include "mono_time.h"
#include "network.h"
#include "ping.h"
#include "shared_key_cache.h"
#include "state.h"
#include "util.h"
@ -46,6 +47,10 @@
// TODO(sudden6): find out why we need multiple callbacks and if we really need 32
#define DHT_FRIEND_MAX_LOCKS 32
/* Settings for the shared key cache */
#define MAX_KEYS_PER_SLOT 4
#define KEYS_TIMEOUT 600
typedef struct DHT_Friend_Callback {
dht_ip_cb *ip_callback;
void *data;
@ -107,8 +112,8 @@ struct DHT {
uint32_t loaded_num_nodes;
unsigned int loaded_nodes_index;
Shared_Keys shared_keys_recv;
Shared_Keys shared_keys_sent;
Shared_Key_Cache *shared_keys_recv;
Shared_Key_Cache *shared_keys_sent;
struct Ping *ping;
Ping_Array *dht_ping_array;
@ -255,74 +260,22 @@ unsigned int bit_by_bit_cmp(const uint8_t *pk1, const uint8_t *pk2)
return i * 8 + j;
}
/**
* Shared key generations are costly, it is therefore smart to store commonly used
* ones so that they can be re-used later without being computed again.
*
* If a shared key is already in shared_keys, copy it to shared_key.
* Otherwise generate it into shared_key and copy it to shared_keys
*/
void get_shared_key(const Mono_Time *mono_time, Shared_Keys *shared_keys, uint8_t *shared_key,
const uint8_t *secret_key, const uint8_t *public_key)
{
uint32_t num = -1;
uint32_t curr = 0;
for (uint32_t i = 0; i < MAX_KEYS_PER_SLOT; ++i) {
const int index = public_key[30] * MAX_KEYS_PER_SLOT + i;
Shared_Key *const key = &shared_keys->keys[index];
if (key->stored) {
if (pk_equal(public_key, key->public_key)) {
memcpy(shared_key, key->shared_key, CRYPTO_SHARED_KEY_SIZE);
++key->times_requested;
key->time_last_requested = mono_time_get(mono_time);
return;
}
if (num != 0) {
if (mono_time_is_timeout(mono_time, key->time_last_requested, KEYS_TIMEOUT)) {
num = 0;
curr = index;
} else if (num > key->times_requested) {
num = key->times_requested;
curr = index;
}
}
} else if (num != 0) {
num = 0;
curr = index;
}
}
encrypt_precompute(public_key, secret_key, shared_key);
if (num != UINT32_MAX) {
Shared_Key *const key = &shared_keys->keys[curr];
key->stored = true;
key->times_requested = 1;
memcpy(key->public_key, public_key, CRYPTO_PUBLIC_KEY_SIZE);
memcpy(key->shared_key, shared_key, CRYPTO_SHARED_KEY_SIZE);
key->time_last_requested = mono_time_get(mono_time);
}
}
/**
* Copy shared_key to encrypt/decrypt DHT packet from public_key into shared_key
* for packets that we receive.
*/
void dht_get_shared_key_recv(DHT *dht, uint8_t *shared_key, const uint8_t *public_key)
const uint8_t *dht_get_shared_key_recv(DHT *dht, const uint8_t *public_key)
{
get_shared_key(dht->mono_time, &dht->shared_keys_recv, shared_key, dht->self_secret_key, public_key);
return shared_key_cache_lookup(dht->shared_keys_recv, public_key);
}
/**
* Copy shared_key to encrypt/decrypt DHT packet from public_key into shared_key
* for packets that we send.
*/
void dht_get_shared_key_sent(DHT *dht, uint8_t *shared_key, const uint8_t *public_key)
const uint8_t *dht_get_shared_key_sent(DHT *dht, const uint8_t *public_key)
{
get_shared_key(dht->mono_time, &dht->shared_keys_sent, shared_key, dht->self_secret_key, public_key);
return shared_key_cache_lookup(dht->shared_keys_sent, public_key);
}
#define CRYPTO_SIZE (1 + CRYPTO_PUBLIC_KEY_SIZE * 2 + CRYPTO_NONCE_SIZE)
@ -1063,8 +1016,7 @@ static bool send_announce_ping(DHT *dht, const uint8_t *public_key, const IP_Por
public_key, CRYPTO_PUBLIC_KEY_SIZE);
memcpy(plain + CRYPTO_PUBLIC_KEY_SIZE, &ping_id, sizeof(ping_id));
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_sent(dht, shared_key, public_key);
const uint8_t *shared_key = dht_get_shared_key_sent(dht, public_key);
uint8_t request[1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE + sizeof(plain) + CRYPTO_MAC_SIZE];
@ -1092,8 +1044,7 @@ static int handle_data_search_response(void *object, const IP_Port *source,
VLA(uint8_t, plain, plain_len);
const uint8_t *public_key = packet + 1;
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_recv(dht, shared_key, public_key);
const uint8_t *shared_key = dht_get_shared_key_recv(dht, public_key);
if (decrypt_data_symmetric(shared_key,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,
@ -1522,15 +1473,12 @@ bool dht_getnodes(DHT *dht, const IP_Port *ip_port, const uint8_t *public_key, c
memcpy(plain, client_id, CRYPTO_PUBLIC_KEY_SIZE);
memcpy(plain + CRYPTO_PUBLIC_KEY_SIZE, &ping_id, sizeof(ping_id));
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_sent(dht, shared_key, public_key);
const uint8_t *shared_key = dht_get_shared_key_sent(dht, public_key);
const int len = dht_create_packet(dht->rng,
dht->self_public_key, shared_key, NET_PACKET_GET_NODES,
plain, sizeof(plain), data, sizeof(data));
crypto_memzero(shared_key, sizeof(shared_key));
if (len != sizeof(data)) {
LOGGER_ERROR(dht->log, "getnodes packet encryption failed");
return false;
@ -1605,9 +1553,7 @@ static int handle_getnodes(void *object, const IP_Port *source, const uint8_t *p
}
uint8_t plain[CRYPTO_NODE_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_recv(dht, shared_key, packet + 1);
const uint8_t *shared_key = dht_get_shared_key_recv(dht, packet + 1);
const int len = decrypt_data_symmetric(
shared_key,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,
@ -1616,7 +1562,6 @@ static int handle_getnodes(void *object, const IP_Port *source, const uint8_t *p
plain);
if (len != CRYPTO_NODE_SIZE) {
crypto_memzero(shared_key, sizeof(shared_key));
return 1;
}
@ -1624,8 +1569,6 @@ static int handle_getnodes(void *object, const IP_Port *source, const uint8_t *p
ping_add(dht->ping, packet + 1, source);
crypto_memzero(shared_key, sizeof(shared_key));
return 0;
}
@ -1670,8 +1613,7 @@ static bool handle_sendnodes_core(void *object, const IP_Port *source, const uin
}
VLA(uint8_t, plain, 1 + data_size + sizeof(uint64_t));
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_sent(dht, shared_key, packet + 1);
const uint8_t *shared_key = dht_get_shared_key_sent(dht, packet + 1);
const int len = decrypt_data_symmetric(
shared_key,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,
@ -1679,8 +1621,6 @@ static bool handle_sendnodes_core(void *object, const IP_Port *source, const uin
1 + data_size + sizeof(uint64_t) + CRYPTO_MAC_SIZE,
plain);
crypto_memzero(shared_key, sizeof(shared_key));
if ((unsigned int)len != SIZEOF_VLA(plain)) {
return false;
}
@ -2796,6 +2736,15 @@ DHT *new_dht(const Logger *log, const Random *rng, const Network *ns, Mono_Time
crypto_new_keypair(rng, dht->self_public_key, dht->self_secret_key);
dht->shared_keys_recv = shared_key_cache_new(mono_time, dht->self_secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
dht->shared_keys_sent = shared_key_cache_new(mono_time, dht->self_secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
if (dht->shared_keys_recv == nullptr || dht->shared_keys_sent == nullptr) {
kill_dht(dht);
return nullptr;
}
dht->dht_ping_array = ping_array_new(DHT_PING_ARRAY_SIZE, PING_TIMEOUT);
if (dht->dht_ping_array == nullptr) {
@ -2858,12 +2807,12 @@ void kill_dht(DHT *dht)
networking_registerhandler(dht->net, NET_PACKET_LAN_DISCOVERY, nullptr, nullptr);
cryptopacket_registerhandler(dht, CRYPTO_PACKET_NAT_PING, nullptr, nullptr);
shared_key_cache_free(dht->shared_keys_recv);
shared_key_cache_free(dht->shared_keys_sent);
ping_array_kill(dht->dht_ping_array);
ping_kill(dht->ping);
free(dht->friends_list);
free(dht->loaded_nodes_list);
crypto_memzero(&dht->shared_keys_recv, sizeof(dht->shared_keys_recv));
crypto_memzero(&dht->shared_keys_sent, sizeof(dht->shared_keys_sent));
crypto_memzero(dht->self_secret_key, sizeof(dht->self_secret_key));
free(dht);
}

34
toxcore/DHT.h
View File

@ -254,24 +254,6 @@ non_null(1, 4) nullable(3)
int unpack_nodes(Node_format *nodes, uint16_t max_num_nodes, uint16_t *processed_data_len, const uint8_t *data,
uint16_t length, bool tcp_enabled);
/*----------------------------------------------------------------------------------*/
/* struct to store some shared keys so we don't have to regenerate them for each request. */
#define MAX_KEYS_PER_SLOT 4
#define KEYS_TIMEOUT 600
typedef struct Shared_Key {
uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
uint32_t times_requested;
bool stored;
uint64_t time_last_requested;
} Shared_Key;
typedef struct Shared_Keys {
Shared_Key keys[256 * MAX_KEYS_PER_SLOT];
} Shared_Keys;
/*----------------------------------------------------------------------------------*/
typedef int cryptopacket_handler_cb(void *object, const IP_Port *ip_port, const uint8_t *source_pubkey,
@ -295,31 +277,19 @@ non_null() const uint8_t *dht_get_friend_public_key(const DHT *dht, uint32_t fri
/*----------------------------------------------------------------------------------*/
/**
* Shared key generations are costly, it is therefore smart to store commonly used
* ones so that they can be re-used later without being computed again.
*
* If a shared key is already in shared_keys, copy it to shared_key.
* Otherwise generate it into shared_key and copy it to shared_keys
*/
non_null()
void get_shared_key(
const Mono_Time *mono_time, Shared_Keys *shared_keys, uint8_t *shared_key,
const uint8_t *secret_key, const uint8_t *public_key);
/**
* Copy shared_key to encrypt/decrypt DHT packet from public_key into shared_key
* for packets that we receive.
*/
non_null()
void dht_get_shared_key_recv(DHT *dht, uint8_t *shared_key, const uint8_t *public_key);
const uint8_t *dht_get_shared_key_recv(DHT *dht, const uint8_t *public_key);
/**
* Copy shared_key to encrypt/decrypt DHT packet from public_key into shared_key
* for packets that we send.
*/
non_null()
void dht_get_shared_key_sent(DHT *dht, uint8_t *shared_key, const uint8_t *public_key);
const uint8_t *dht_get_shared_key_sent(DHT *dht, const uint8_t *public_key);
/**
* Sends a getnodes request to `ip_port` with the public key `public_key` for nodes

2
toxcore/Makefile.inc
View File

@ -61,6 +61,8 @@ libtoxcore_la_SOURCES = ../third_party/cmp/cmp.c \
../toxcore/Messenger.c \
../toxcore/ping.h \
../toxcore/ping.c \
../toxcore/shared_key_cache.h \
../toxcore/shared_key_cache.c \
../toxcore/state.h \
../toxcore/state.c \
../toxcore/tox.h \

27
toxcore/announce.c
View File

@ -14,9 +14,14 @@
#include "LAN_discovery.h"
#include "ccompat.h"
#include "shared_key_cache.h"
#include "timed_auth.h"
#include "util.h"
// Settings for the shared key cache
#define MAX_KEYS_PER_SLOT 4
#define KEYS_TIMEOUT 600
uint8_t announce_response_of_request_type(uint8_t request_type)
{
switch (request_type) {
@ -53,7 +58,7 @@ struct Announcements {
const uint8_t *public_key;
const uint8_t *secret_key;
Shared_Keys shared_keys;
Shared_Key_Cache *shared_keys;
uint8_t hmac_key[CRYPTO_HMAC_KEY_SIZE];
int32_t synch_offset;
@ -429,10 +434,13 @@ static int create_reply_plain_store_announce_request(Announcements *announce,
}
VLA(uint8_t, plain, plain_len);
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
get_shared_key(announce->mono_time, &announce->shared_keys, shared_key,
announce->secret_key, data_public_key);
const uint8_t* shared_key = shared_key_cache_lookup(announce->shared_keys, data_public_key);
if (shared_key == nullptr) {
/* Error looking up/deriving the shared key */
return -1;
}
if (decrypt_data_symmetric(shared_key,
data + CRYPTO_PUBLIC_KEY_SIZE,
@ -549,9 +557,7 @@ static int create_reply(Announcements *announce, const IP_Port *source,
}
VLA(uint8_t, plain, plain_len);
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
dht_get_shared_key_recv(announce->dht, shared_key, data + 1);
const uint8_t *shared_key = dht_get_shared_key_recv(announce->dht, data + 1);
if (decrypt_data_symmetric(shared_key,
data + 1 + CRYPTO_PUBLIC_KEY_SIZE,
@ -652,6 +658,11 @@ Announcements *new_announcements(const Logger *log, const Random *rng, const Mon
announce->public_key = dht_get_self_public_key(announce->dht);
announce->secret_key = dht_get_self_secret_key(announce->dht);
new_hmac_key(announce->rng, announce->hmac_key);
announce->shared_keys = shared_key_cache_new(mono_time, announce->secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
if (announce->shared_keys == nullptr) {
free(announce);
return nullptr;
}
announce->start_time = mono_time_get(announce->mono_time);
@ -677,7 +688,7 @@ void kill_announcements(Announcements *announce)
networking_registerhandler(announce->net, NET_PACKET_STORE_ANNOUNCE_REQUEST, nullptr, nullptr);
crypto_memzero(announce->hmac_key, CRYPTO_HMAC_KEY_SIZE);
crypto_memzero(&announce->shared_keys, sizeof(Shared_Keys));
shared_key_cache_free(announce->shared_keys);
for (uint32_t i = 0; i < ANNOUNCE_BUCKETS * ANNOUNCE_BUCKET_SIZE; ++i) {
if (announce->entries[i].data != nullptr) {

7
toxcore/net_crypto.c
View File

@ -223,8 +223,8 @@ static int create_cookie_request(const Net_Crypto *c, uint8_t *packet, const uin
memcpy(plain, c->self_public_key, CRYPTO_PUBLIC_KEY_SIZE);
memcpy(plain + CRYPTO_PUBLIC_KEY_SIZE, padding, CRYPTO_PUBLIC_KEY_SIZE);
memcpy(plain + (CRYPTO_PUBLIC_KEY_SIZE * 2), &number, sizeof(uint64_t));
dht_get_shared_key_sent(c->dht, shared_key, dht_public_key);
const uint8_t *tmp_shared_key = dht_get_shared_key_sent(c->dht, dht_public_key);
memcpy(shared_key, tmp_shared_key, CRYPTO_SHARED_KEY_SIZE);
uint8_t nonce[CRYPTO_NONCE_SIZE];
random_nonce(c->rng, nonce);
packet[0] = NET_PACKET_COOKIE_REQUEST;
@ -341,7 +341,8 @@ static int handle_cookie_request(const Net_Crypto *c, uint8_t *request_plain, ui
}
memcpy(dht_public_key, packet + 1, CRYPTO_PUBLIC_KEY_SIZE);
dht_get_shared_key_sent(c->dht, shared_key, dht_public_key);
const uint8_t *tmp_shared_key = dht_get_shared_key_sent(c->dht, dht_public_key);
memcpy(shared_key, tmp_shared_key, CRYPTO_SHARED_KEY_SIZE);
const int len = decrypt_data_symmetric(shared_key, packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE, COOKIE_REQUEST_PLAIN_LENGTH + CRYPTO_MAC_SIZE,
request_plain);

55
toxcore/onion.c
View File

@ -27,6 +27,11 @@
#define KEY_REFRESH_INTERVAL (2 * 60 * 60)
// Settings for the shared key cache
#define MAX_KEYS_PER_SLOT 4
#define KEYS_TIMEOUT 600
/** Change symmetric keys every 2 hours to make paths expire eventually. */
non_null()
static void change_symmetric_key(Onion *onion)
@ -314,9 +319,14 @@ static int handle_send_initial(void *object, const IP_Port *source, const uint8_
change_symmetric_key(onion);
uint8_t plain[ONION_MAX_PACKET_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
get_shared_key(onion->mono_time, &onion->shared_keys_1, shared_key, dht_get_self_secret_key(onion->dht),
packet + 1 + CRYPTO_NONCE_SIZE);
const uint8_t *public_key = packet + 1 + CRYPTO_NONCE_SIZE;
const uint8_t *shared_key = shared_key_cache_lookup(onion->shared_keys_1, public_key);
if (shared_key == nullptr) {
/* Error looking up/deriving the shared key */
return 1;
}
const int len = decrypt_data_symmetric(shared_key, packet + 1, packet + 1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE,
length - (1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE), plain);
@ -385,9 +395,14 @@ static int handle_send_1(void *object, const IP_Port *source, const uint8_t *pac
change_symmetric_key(onion);
uint8_t plain[ONION_MAX_PACKET_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
get_shared_key(onion->mono_time, &onion->shared_keys_2, shared_key, dht_get_self_secret_key(onion->dht),
packet + 1 + CRYPTO_NONCE_SIZE);
const uint8_t *public_key = packet + 1 + CRYPTO_NONCE_SIZE;
const uint8_t *shared_key = shared_key_cache_lookup(onion->shared_keys_2, public_key);
if (shared_key == nullptr) {
/* Error looking up/deriving the shared key */
return 1;
}
int len = decrypt_data_symmetric(shared_key, packet + 1, packet + 1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE,
length - (1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE + RETURN_1), plain);
@ -443,9 +458,14 @@ static int handle_send_2(void *object, const IP_Port *source, const uint8_t *pac
change_symmetric_key(onion);
uint8_t plain[ONION_MAX_PACKET_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
get_shared_key(onion->mono_time, &onion->shared_keys_3, shared_key, dht_get_self_secret_key(onion->dht),
packet + 1 + CRYPTO_NONCE_SIZE);
const uint8_t *public_key = packet + 1 + CRYPTO_NONCE_SIZE;
const uint8_t *shared_key = shared_key_cache_lookup(onion->shared_keys_3, public_key);
if (shared_key == nullptr) {
/* Error looking up/deriving the shared key */
return 1;
}
int len = decrypt_data_symmetric(shared_key, packet + 1, packet + 1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE,
length - (1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE + RETURN_2), plain);
@ -668,6 +688,19 @@ Onion *new_onion(const Logger *log, const Mono_Time *mono_time, const Random *rn
new_symmetric_key(rng, onion->secret_symmetric_key);
onion->timestamp = mono_time_get(onion->mono_time);
const uint8_t *secret_key = dht_get_self_secret_key(dht);
onion->shared_keys_1 = shared_key_cache_new(mono_time, secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
onion->shared_keys_2 = shared_key_cache_new(mono_time, secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
onion->shared_keys_3 = shared_key_cache_new(mono_time, secret_key, KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
if (onion->shared_keys_1 == nullptr ||
onion->shared_keys_2 == nullptr ||
onion->shared_keys_3 == nullptr) {
kill_onion(onion);
return nullptr;
}
networking_registerhandler(onion->net, NET_PACKET_ONION_SEND_INITIAL, &handle_send_initial, onion);
networking_registerhandler(onion->net, NET_PACKET_ONION_SEND_1, &handle_send_1, onion);
networking_registerhandler(onion->net, NET_PACKET_ONION_SEND_2, &handle_send_2, onion);
@ -695,5 +728,9 @@ void kill_onion(Onion *onion)
crypto_memzero(onion->secret_symmetric_key, sizeof(onion->secret_symmetric_key));
shared_key_cache_free(onion->shared_keys_1);
shared_key_cache_free(onion->shared_keys_2);
shared_key_cache_free(onion->shared_keys_3);
free(onion);
}

7
toxcore/onion.h
View File

@ -12,6 +12,7 @@
#include "DHT.h"
#include "logger.h"
#include "mono_time.h"
#include "shared_key_cache.h"
typedef int onion_recv_1_cb(void *object, const IP_Port *dest, const uint8_t *data, uint16_t length);
@ -24,9 +25,9 @@ typedef struct Onion {
uint8_t secret_symmetric_key[CRYPTO_SYMMETRIC_KEY_SIZE];
uint64_t timestamp;
Shared_Keys shared_keys_1;
Shared_Keys shared_keys_2;
Shared_Keys shared_keys_3;
Shared_Key_Cache *shared_keys_1;
Shared_Key_Cache *shared_keys_2;
Shared_Key_Cache *shared_keys_3;
onion_recv_1_cb *recv_1_function;
void *callback_object;

23
toxcore/onion_announce.c
View File

@ -16,6 +16,7 @@
#include "LAN_discovery.h"
#include "ccompat.h"
#include "mono_time.h"
#include "shared_key_cache.h"
#include "util.h"
#define PING_ID_TIMEOUT ONION_ANNOUNCE_TIMEOUT
@ -31,6 +32,10 @@
#define ONION_MINIMAL_SIZE (ONION_PING_ID_SIZE + CRYPTO_PUBLIC_KEY_SIZE * 2 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH)
/* Settings for the shared key cache */
#define MAX_KEYS_PER_SLOT 4
#define KEYS_TIMEOUT 600
static_assert(ONION_PING_ID_SIZE == CRYPTO_PUBLIC_KEY_SIZE,
"announce response packets assume that ONION_PING_ID_SIZE is equal to CRYPTO_PUBLIC_KEY_SIZE");
@ -51,7 +56,7 @@ struct Onion_Announce {
Onion_Announce_Entry entries[ONION_ANNOUNCE_MAX_ENTRIES];
uint8_t hmac_key[CRYPTO_HMAC_KEY_SIZE];
Shared_Keys shared_keys_recv;
Shared_Key_Cache *shared_keys_recv;
uint16_t extra_data_max_size;
pack_extra_data_cb *extra_data_callback;
@ -426,9 +431,12 @@ static int handle_announce_request_common(
pack_extra_data_cb *pack_extra_data_callback)
{
const uint8_t *packet_public_key = packet + 1 + CRYPTO_NONCE_SIZE;
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
get_shared_key(onion_a->mono_time, &onion_a->shared_keys_recv, shared_key, dht_get_self_secret_key(onion_a->dht),
packet_public_key);
const uint8_t *shared_key = shared_key_cache_lookup(onion_a->shared_keys_recv, packet_public_key);
if (shared_key == nullptr) {
/* Error looking up/deriving the shared key */
return 1;
}
uint8_t *plain = (uint8_t *)malloc(plain_size);
@ -653,6 +661,12 @@ Onion_Announce *new_onion_announce(const Logger *log, const Random *rng, const M
onion_a->extra_data_object = nullptr;
new_hmac_key(rng, onion_a->hmac_key);
onion_a->shared_keys_recv = shared_key_cache_new(mono_time, dht_get_self_secret_key(dht), KEYS_TIMEOUT, MAX_KEYS_PER_SLOT);
if (onion_a->shared_keys_recv == nullptr) {
kill_onion_announce(onion_a);
return nullptr;
}
networking_registerhandler(onion_a->net, NET_PACKET_ANNOUNCE_REQUEST, &handle_announce_request, onion_a);
networking_registerhandler(onion_a->net, NET_PACKET_ANNOUNCE_REQUEST_OLD, &handle_announce_request_old, onion_a);
networking_registerhandler(onion_a->net, NET_PACKET_ONION_DATA_REQUEST, &handle_data_request, onion_a);
@ -671,6 +685,7 @@ void kill_onion_announce(Onion_Announce *onion_a)
networking_registerhandler(onion_a->net, NET_PACKET_ONION_DATA_REQUEST, nullptr, nullptr);
crypto_memzero(onion_a->hmac_key, CRYPTO_HMAC_KEY_SIZE);
shared_key_cache_free(onion_a->shared_keys_recv);
free(onion_a);
}

20
toxcore/ping.c
View File

@ -53,10 +53,9 @@ void ping_send_request(Ping *ping, const IP_Port *ipp, const uint8_t *public_key
return;
}
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
// generate key to encrypt ping_id with recipient privkey
dht_get_shared_key_sent(ping->dht, shared_key, public_key);
const uint8_t *shared_key = dht_get_shared_key_sent(ping->dht, public_key);
// Generate random ping_id.
uint8_t data[PING_DATA_SIZE];
pk_copy(data, public_key);
@ -64,7 +63,6 @@ void ping_send_request(Ping *ping, const IP_Port *ipp, const uint8_t *public_key
ping_id = ping_array_add(ping->ping_array, ping->mono_time, ping->rng, data, sizeof(data));
if (ping_id == 0) {
crypto_memzero(shared_key, sizeof(shared_key));
return;
}
@ -82,8 +80,6 @@ void ping_send_request(Ping *ping, const IP_Port *ipp, const uint8_t *public_key
ping_plain, sizeof(ping_plain),
pk + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE);
crypto_memzero(shared_key, sizeof(shared_key));
if (rc != PING_PLAIN_SIZE + CRYPTO_MAC_SIZE) {
return;
}
@ -139,11 +135,11 @@ static int handle_ping_request(void *object, const IP_Port *source, const uint8_
return 1;
}
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
const uint8_t *shared_key = dht_get_shared_key_recv(dht, packet + 1);
uint8_t ping_plain[PING_PLAIN_SIZE];
// Decrypt ping_id
dht_get_shared_key_recv(dht, shared_key, packet + 1);
const int rc = decrypt_data_symmetric(shared_key,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,
packet + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE,
@ -151,12 +147,10 @@ static int handle_ping_request(void *object, const IP_Port *source, const uint8_
ping_plain);
if (rc != sizeof(ping_plain)) {
crypto_memzero(shared_key, sizeof(shared_key));
return 1;
}
if (ping_plain[0] != NET_PACKET_PING_REQUEST) {
crypto_memzero(shared_key, sizeof(shared_key));
return 1;
}
@ -166,8 +160,6 @@ static int handle_ping_request(void *object, const IP_Port *source, const uint8_
ping_send_response(ping, source, packet + 1, ping_id, shared_key);
ping_add(ping, packet + 1, source);
crypto_memzero(shared_key, sizeof(shared_key));
return 0;
}
@ -188,10 +180,8 @@ static int handle_ping_response(void *object, const IP_Port *source, const uint8
return 1;
}
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
// generate key to encrypt ping_id with recipient privkey
dht_get_shared_key_sent(ping->dht, shared_key, packet + 1);
const uint8_t *shared_key = dht_get_shared_key_sent(ping->dht, packet + 1);
uint8_t ping_plain[PING_PLAIN_SIZE];
// Decrypt ping_id
@ -201,8 +191,6 @@ static int handle_ping_response(void *object, const IP_Port *source, const uint8
PING_PLAIN_SIZE + CRYPTO_MAC_SIZE,
ping_plain);
crypto_memzero(shared_key, sizeof(shared_key));
if (rc != sizeof(ping_plain)) {
return 1;
}

161
toxcore/shared_key_cache.c Normal file
View File

@ -0,0 +1,161 @@
/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2022 The TokTok team.
*/
#include "shared_key_cache.h"
#include <assert.h>
#include <stdint.h>
#include <stdlib.h> // calloc(...)
#include <string.h> // memcpy(...)
#include "ccompat.h"
#include "crypto_core.h"
#include "mono_time.h"
typedef struct Shared_Key {
uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
uint64_t time_last_requested;
} Shared_Key;
struct Shared_Key_Cache {
Shared_Key *keys;
const uint8_t* self_secret_key;
uint64_t timeout; /** After this time (in seconds), a key is erased on the next housekeeping cycle */
const Mono_Time *time;
uint8_t keys_per_slot;
};
non_null()
static bool shared_key_is_empty(const Shared_Key *k) {
assert(k != nullptr);
/*
* Since time can never be 0, we use that to determine if a key slot is empty.
* Additionally this allows us to use crypto_memzero and leave the slot in a valid state.
*/
return k->time_last_requested == 0;
}
non_null()
static void shared_key_set_empty(Shared_Key *k) {
crypto_memzero(k, sizeof (Shared_Key));
assert(shared_key_is_empty(k));
}
Shared_Key_Cache *shared_key_cache_new(const Mono_Time *time, const uint8_t *self_secret_key, uint64_t timeout, uint8_t keys_per_slot)
{
if (time == nullptr || self_secret_key == nullptr || timeout == 0 || keys_per_slot == 0) {
return nullptr;
}
// Time must not be zero, since we use that as special value for empty slots
if (mono_time_get(time) == 0) {
// Fail loudly in debug environments
assert(false);
return nullptr;
}
Shared_Key_Cache *res = (Shared_Key_Cache *)calloc(1, sizeof (Shared_Key_Cache));
if (res == nullptr) {
return nullptr;
}
res->self_secret_key = self_secret_key;
res->time = time;
res->keys_per_slot = keys_per_slot;
// We take one byte from the public key for each bucket and store keys_per_slot elements there
const size_t cache_size = 256 * keys_per_slot;
res->keys = (Shared_Key *)calloc(cache_size, sizeof (Shared_Key));
if (res->keys == nullptr) {
free(res);
return nullptr;
}
crypto_memlock(res->keys, cache_size * sizeof (Shared_Key));
return res;
}
void shared_key_cache_free(Shared_Key_Cache *cache)
{
if (cache == nullptr) {
return;
}
const size_t cache_size = 256 * cache->keys_per_slot;
// Don't leave key material in memory
crypto_memzero(cache->keys, cache_size * sizeof (Shared_Key));
crypto_memunlock(cache->keys, cache_size * sizeof (Shared_Key));
free(cache->keys);
free(cache);
}
/* NOTE: On each lookup housekeeping is performed to evict keys that did timeout. */
const uint8_t *shared_key_cache_lookup(Shared_Key_Cache *cache, const uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE])
{
// caching the time is not necessary, but calls to mono_time_get(...) are not free
const uint64_t cur_time = mono_time_get(cache->time);
// We can't use the first and last bytes because they are masked in curve25519. Selected 8 for good alignment.
const uint8_t bucket_idx = public_key[8];
Shared_Key* bucket_start = &cache->keys[bucket_idx*cache->keys_per_slot];
const uint8_t* found = nullptr;
// Perform lookup
for(size_t i = 0; i < cache->keys_per_slot; ++i) {
if (shared_key_is_empty(&bucket_start[i])) {
continue;
}
if (pk_equal(public_key, bucket_start[i].public_key)) {
found = bucket_start[i].shared_key;
bucket_start[i].time_last_requested = cur_time;
break;
}
}
// Perform housekeeping for this bucket
for (size_t i = 0; i < cache->keys_per_slot; ++i) {
if (shared_key_is_empty(&bucket_start[i])) {
continue;
}
const bool timed_out = (bucket_start[i].time_last_requested + cache->timeout) < cur_time;
if (timed_out) {
shared_key_set_empty(&bucket_start[i]);
}
}
if (found == nullptr) {
// Insert into cache
uint64_t oldest_timestamp = UINT64_MAX;
size_t oldest_index = 0;
/*
* Find least recently used entry, unused entries are prioritised,
* because their time_last_requested field is zeroed.
*/
for (size_t i = 0; i < cache->keys_per_slot; ++i) {
if (bucket_start[i].time_last_requested < oldest_timestamp) {
oldest_timestamp = bucket_start[i].time_last_requested;
oldest_index = i;
}
}
// Compute the shared key for the cache
if (encrypt_precompute(public_key, cache->self_secret_key, bucket_start[oldest_index].shared_key) != 0) {
// Don't put anything in the cache on error
return nullptr;
}
// update cache entry
memcpy(bucket_start[oldest_index].public_key, public_key, CRYPTO_PUBLIC_KEY_SIZE);
bucket_start[oldest_index].time_last_requested = cur_time;
found = bucket_start[oldest_index].shared_key;
}
return found;
}

51
toxcore/shared_key_cache.h Normal file
View File

@ -0,0 +1,51 @@
/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2022 The TokTok team.
*/
#ifndef C_TOXCORE_TOXCORE_SHARED_KEY_CACHE_H
#define C_TOXCORE_TOXCORE_SHARED_KEY_CACHE_H
#include <stdint.h> // uint*_t
#include "crypto_core.h"
#include "mono_time.h"
/**
* This implements a cache for shared keys, since key generation is expensive.
*/
typedef struct Shared_Key_Cache Shared_Key_Cache;
/**
* @brief Initializes a new shared key cache.
* @param time Time object for retrieving current time.
* @param self_secret_key Our own secret key of length CRYPTO_SECRET_KEY_SIZE,
* it must not change during the lifetime of the cache.
* @param timeout Number of milliseconds, after which a key should be evicted.
* @param keys_per_slot There are 256 slots, this controls how many keys are stored per slot and the size of the cache.
* @return nullptr on error.
*/
non_null()
Shared_Key_Cache *shared_key_cache_new(const Mono_Time *time,
const uint8_t *self_secret_key,
uint64_t timeout, uint8_t keys_per_slot);
/**
* @brief Deletes the cache and frees all resources.
* @param cache Cache to delete or nullptr.
*/
nullable(1)
void shared_key_cache_free(Shared_Key_Cache *cache);
/**
* @brief Looks up a key from the cache or computes it if it didn't exist yet.
* @param cache Cache to perform the lookup on.
* @param public_key Public key, used for the lookup and computation.
*
* @return The shared key of length CRYPTO_SHARED_KEY_SIZE, matching the public key and our secret key.
* @return nullptr on error.
*/
non_null()
const uint8_t* shared_key_cache_lookup(Shared_Key_Cache *cache, const uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE]);
#endif // C_TOXCORE_TOXCORE_SHARED_KEY_CACHE_H