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- Fix #1415: [dnscrypt] shared secret cache, patch from

Browse source 
Manu Bretelle.


git-svn-id: file:///svn/unbound/trunk@4312 be551aaa-1e26-0410-a405-d3ace91eadb9
This commit is contained in:
Wouter Wijngaards 2017-08-28 10:55:41 +00:00
parent cd46a535cd
commit e3cc298ffd
4 changed files with 270 additions and 47 deletions
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208
dnscrypt/dnscrypt.c
View file

@ -12,6 +12,8 @@
#include "util/net_help.h"
#include "util/netevent.h"
#include "util/log.h"
#include "util/storage/slabhash.h"
#include "util/storage/lookup3.h"
#include "dnscrypt/cert.h"
#include "dnscrypt/dnscrypt.h"
@ -19,13 +21,15 @@
#include <ctype.h>
/**
* \file
* dnscrypt functions for encrypting DNS packets.
*/
#define DNSCRYPT_QUERY_BOX_OFFSET \
(DNSCRYPT_MAGIC_HEADER_LEN + crypto_box_PUBLICKEYBYTES + crypto_box_HALF_NONCEBYTES)
(DNSCRYPT_MAGIC_HEADER_LEN + crypto_box_PUBLICKEYBYTES + \
crypto_box_HALF_NONCEBYTES)
// 8 bytes: magic header (CERT_MAGIC_HEADER)
// 12 bytes: the client's nonce
@ -33,13 +37,110 @@
// 16 bytes: Poly1305 MAC (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES)
#define DNSCRYPT_REPLY_BOX_OFFSET \
(DNSCRYPT_MAGIC_HEADER_LEN + crypto_box_HALF_NONCEBYTES + crypto_box_HALF_NONCEBYTES)
(DNSCRYPT_MAGIC_HEADER_LEN + crypto_box_HALF_NONCEBYTES + \
crypto_box_HALF_NONCEBYTES)
/**
* Shared secret cache key length.
* secret key.
* 1 byte: ES_VERSION[1]
* 32 bytes: client crypto_box_PUBLICKEYBYTES
* 32 bytes: server crypto_box_SECRETKEYBYTES
*/
#define DNSCRYPT_SHARED_SECRET_KEY_LENGTH \
(1 + crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES)
struct shared_secret_cache_key {
/** the hash table key */
uint8_t key[DNSCRYPT_SHARED_SECRET_KEY_LENGTH];
/** the hash table entry, data is struct reply_info* */
struct lruhash_entry entry;
};
/**
* Generate a key suitable to find shared secret in slabhash.
* \param[in] key: a uint8_t pointer of size DNSCRYPT_SHARED_SECRET_KEY_LENGTH
* \param[in] esversion: The es version least significant byte.
* \param[in] pk: The public key of the client. uint8_t pointer of size
* crypto_box_PUBLICKEYBYTES.
* \param[in] sk: The secret key of the server matching the magic query number.
* uint8_t pointer of size crypto_box_SECRETKEYBYTES.
* \return the hash of the key.
*/
static uint32_t
dnsc_shared_secrets_cache_key(uint8_t* key,
uint8_t esversion,
uint8_t* pk,
uint8_t* sk)
{
key[0] = esversion;
memcpy(key + 1, pk, crypto_box_PUBLICKEYBYTES);
memcpy(key + 1 + crypto_box_PUBLICKEYBYTES, sk, crypto_box_SECRETKEYBYTES);
return hashlittle(key, DNSCRYPT_SHARED_SECRET_KEY_LENGTH, 0);
}
/**
* Inserts a shared secret into the shared_secrets_cache slabhash.
* The shared secret is copied so the caller can use it freely without caring
* about the cache entry being evicted or not.
* \param[in] cache: the slabhash in which to look for the key.
* \param[in] key: a uint8_t pointer of size DNSCRYPT_SHARED_SECRET_KEY_LENGTH
* which contains the key of the shared secret.
* \param[in] hash: the hash of the key.
* \param[in] nmkey: a uint8_t pointer of size crypto_box_BEFORENMBYTES which
* contains the shared secret.
*/
static void
dnsc_shared_secret_cache_insert(struct slabhash *cache,
uint8_t key[DNSCRYPT_SHARED_SECRET_KEY_LENGTH],
uint32_t hash,
uint8_t nmkey[crypto_box_BEFORENMBYTES])
{
struct shared_secret_cache_key* k =
(struct shared_secret_cache_key*)calloc(1, sizeof(*k));
uint8_t* d = malloc(crypto_box_BEFORENMBYTES);
if(!k || !d) {
free(k);
free(d);
return;
}
memcpy(d, nmkey, crypto_box_BEFORENMBYTES);
lock_rw_init(&k->entry.lock);
memcpy(k->key, key, DNSCRYPT_SHARED_SECRET_KEY_LENGTH);
k->entry.hash = hash;
k->entry.key = k;
k->entry.data = d;
slabhash_insert(cache,
hash, &k->entry,
d,
NULL);
}
/**
* Lookup a record in shared_secrets_cache.
* \param[in] cache: a pointer to shared_secrets_cache slabhash.
* \param[in] key: a uint8_t pointer of size DNSCRYPT_SHARED_SECRET_KEY_LENGTH
* containing the key to look for.
* \param[in] hash: a hash of the key.
* \return a pointer to the locked cache entry or NULL on failure.
*/
static struct lruhash_entry*
dnsc_shared_secrets_lookup(struct slabhash* cache,
uint8_t key[DNSCRYPT_SHARED_SECRET_KEY_LENGTH],
uint32_t hash)
{
return slabhash_lookup(cache, hash, key, 0);
}
/**
* Decrypt a query using the dnsccert that was found using dnsc_find_cert.
* The client nonce will be extracted from the encrypted query and stored in
* client_nonce, a shared secret will be computed and stored in nmkey and the
* buffer will be decrypted inplace.
* \param[in] env the dnscrypt environment.
* \param[in] cert the cert that matches this encrypted query.
* \param[in] client_nonce where the client nonce will be stored.
* \param[in] nmkey where the shared secret key will be written.
@ -47,7 +148,8 @@
* \return 0 on success.
*/
static int
dnscrypt_server_uncurve(const dnsccert *cert,
dnscrypt_server_uncurve(struct dnsc_env* env,
const dnsccert *cert,
uint8_t client_nonce[crypto_box_HALF_NONCEBYTES],
uint8_t nmkey[crypto_box_BEFORENMBYTES],
struct sldns_buffer* buffer)
@ -56,27 +158,52 @@ dnscrypt_server_uncurve(const dnsccert *cert,
uint8_t *const buf = sldns_buffer_begin(buffer);
uint8_t nonce[crypto_box_NONCEBYTES];
struct dnscrypt_query_header *query_header;
// shared secret cache
uint8_t key[DNSCRYPT_SHARED_SECRET_KEY_LENGTH];
struct lruhash_entry* entry;
uint32_t hash;
if (len <= DNSCRYPT_QUERY_HEADER_SIZE) {
return -1;
}
query_header = (struct dnscrypt_query_header *)buf;
memcpy(nmkey, query_header->publickey, crypto_box_PUBLICKEYBYTES);
hash = dnsc_shared_secrets_cache_key(key,
cert->es_version[1],
query_header->publickey,
cert->keypair->crypt_secretkey);
entry = dnsc_shared_secrets_lookup(env->shared_secrets_cache,
key,
hash);
if(!entry) {
if(cert->es_version[1] == 2) {
#ifdef USE_DNSCRYPT_XCHACHA20
if (crypto_box_curve25519xchacha20poly1305_beforenm(
nmkey, nmkey, cert->keypair->crypt_secretkey) != 0) {
nmkey, query_header->publickey,
cert->keypair->crypt_secretkey) != 0) {
return -1;
}
#else
return -1;
#endif
} else {
if (crypto_box_beforenm(nmkey, nmkey, cert->keypair->crypt_secretkey) != 0) {
if (crypto_box_beforenm(nmkey,
query_header->publickey,
cert->keypair->crypt_secretkey) != 0) {
return -1;
}
}
// Cache the shared secret we just computed.
dnsc_shared_secret_cache_insert(env->shared_secrets_cache,
key,
hash,
nmkey);
} else {
/* copy shared secret and unlock entry */
memcpy(nmkey, entry->data, crypto_box_BEFORENMBYTES);
lock_rw_unlock(&entry->lock);
}
memcpy(nonce, query_header->nonce, crypto_box_HALF_NONCEBYTES);
memset(nonce + crypto_box_HALF_NONCEBYTES, 0, crypto_box_HALF_NONCEBYTES);
@ -223,7 +350,8 @@ dnscrypt_server_curve(const dnsccert *cert,
size_t max_udp_size)
{
size_t dns_reply_len = sldns_buffer_limit(buffer);
size_t max_len = dns_reply_len + DNSCRYPT_MAX_PADDING + DNSCRYPT_REPLY_HEADER_SIZE;
size_t max_len = dns_reply_len + DNSCRYPT_MAX_PADDING \
+ DNSCRYPT_REPLY_HEADER_SIZE;
size_t max_reply_size = max_udp_size - 20U - 8U;
uint8_t nonce[crypto_box_NONCEBYTES];
uint8_t *boxed;
@ -268,8 +396,14 @@ dnscrypt_server_curve(const dnsccert *cert,
}
}
sldns_buffer_write_at(buffer, 0, DNSCRYPT_MAGIC_RESPONSE, DNSCRYPT_MAGIC_HEADER_LEN);
sldns_buffer_write_at(buffer, DNSCRYPT_MAGIC_HEADER_LEN, nonce, crypto_box_NONCEBYTES);
sldns_buffer_write_at(buffer,
0,
DNSCRYPT_MAGIC_RESPONSE,
DNSCRYPT_MAGIC_HEADER_LEN);
sldns_buffer_write_at(buffer,
DNSCRYPT_MAGIC_HEADER_LEN,
nonce,
crypto_box_NONCEBYTES);
sldns_buffer_set_limit(buffer, len + DNSCRYPT_REPLY_HEADER_SIZE);
return 0;
}
@ -379,7 +513,7 @@ dnsc_key_to_fingerprint(char fingerprint[80U], const uint8_t * const key)
/**
* Find the cert matching a DNSCrypt query.
* \param[in] dnscenv The DNSCrypt enviroment, which contains the list of certs
* \param[in] dnscenv The DNSCrypt environment, which contains the list of certs
* supported by the server.
* \param[in] buffer The encrypted DNS query.
* \return a dnsccert * if we found a cert matching the magic_number of the
@ -585,7 +719,8 @@ dnsc_handle_curved_request(struct dnsc_env* dnscenv,
// to serve the certificate.
verbose(VERB_ALGO, "handle request called on DNSCrypt socket");
if ((repinfo->dnsc_cert = dnsc_find_cert(dnscenv, c->buffer)) != NULL) {
if(dnscrypt_server_uncurve(repinfo->dnsc_cert,
if(dnscrypt_server_uncurve(dnscenv,
repinfo->dnsc_cert,
repinfo->client_nonce,
repinfo->nmkey,
c->buffer) != 0){
@ -648,6 +783,19 @@ dnsc_apply_cfg(struct dnsc_env *env, struct config_file *cfg)
if(dnsc_load_local_data(env, cfg) <= 0) {
fatal_exit("dnsc_apply_cfg: could not load local data");
}
env->shared_secrets_cache = slabhash_create(
cfg->msg_cache_slabs,
HASH_DEFAULT_STARTARRAY,
cfg->msg_cache_size,
dnsc_shared_secrets_sizefunc,
dnsc_shared_secrets_compfunc,
dnsc_shared_secrets_delkeyfunc,
dnsc_shared_secrets_deldatafunc,
NULL
);
if(!env->shared_secrets_cache){
fatal_exit("dnsc_apply_cfg: could not create shared secrets cache.");
}
return 0;
}
@ -661,5 +809,43 @@ dnsc_delete(struct dnsc_env *env)
sodium_free(env->signed_certs);
sodium_free(env->certs);
sodium_free(env->keypairs);
slabhash_delete(env->shared_secrets_cache);
free(env);
}
/**
* #########################################################
* ############# Shared secrets cache functions ############
* #########################################################
*/
size_t
dnsc_shared_secrets_sizefunc(void *k, void *d)
{
struct shared_secret_cache_key* ssk = (struct shared_secret_cache_key*)k;
size_t key_size = sizeof(struct shared_secret_cache_key)
+ lock_get_mem(&ssk->entry.lock);
size_t data_size = crypto_box_BEFORENMBYTES;
return key_size + data_size;
}
int
dnsc_shared_secrets_compfunc(void *m1, void *m2)
{
return sodium_memcmp(m1, m2, DNSCRYPT_SHARED_SECRET_KEY_LENGTH);
}
void
dnsc_shared_secrets_delkeyfunc(void *k, void* ATTR_UNUSED(arg))
{
struct shared_secret_cache_key* ssk = (struct shared_secret_cache_key*)k;
lock_rw_destroy(&ssk->entry.lock);
free(ssk);
}
void
dnsc_shared_secrets_deldatafunc(void* d, void* ATTR_UNUSED(arg))
{
uint8_t* data = (uint8_t*)d;
free(data);
}

23
dnscrypt/dnscrypt.h
View file

@ -38,6 +38,7 @@
struct sldns_buffer;
struct config_file;
struct comm_reply;
struct slabhash;
typedef struct KeyPair_ {
uint8_t crypt_publickey[crypto_box_PUBLICKEYBYTES];
@ -61,6 +62,7 @@ struct dnsc_env {
uint64_t nonce_ts_last;
unsigned char hash_key[crypto_shorthash_KEYBYTES];
char * provider_name;
struct slabhash *shared_secrets_cache;
};
struct dnscrypt_query_header {
@ -111,5 +113,26 @@ int dnsc_handle_curved_request(struct dnsc_env* dnscenv,
*/
int dnsc_handle_uncurved_request(struct comm_reply *repinfo);
/**
* Computes the size of the shared secret cache entry.
*/
size_t dnsc_shared_secrets_sizefunc(void *k, void *d);
/**
* Compares two shared secret cache keys.
*/
int dnsc_shared_secrets_compfunc(void *m1, void *m2);
/**
* Function to delete a shared secret cache key.
*/
void dnsc_shared_secrets_delkeyfunc(void *k, void* arg);
/**
* Function to delete a share secret cache value.
*/
void dnsc_shared_secrets_deldatafunc(void* d, void* arg);
#endif /* USE_DNSCRYPT */
#endif

2
doc/Changelog
View file

@ -1,6 +1,8 @@
28 August 2017: Wouter
- Fix #1415: patch to free dnscrypt environment on reload.
- iana portlist update
- Fix #1415: [dnscrypt] shared secret cache, patch from
Manu Bretelle.
23 August 2017: Wouter
- Fix #1407: Add ECS options check to unbound-checkconf.

12
util/fptr_wlist.c
View file

@ -230,6 +230,9 @@ fptr_whitelist_hash_sizefunc(lruhash_sizefunc_type fptr)
else if(fptr == &test_slabhash_sizefunc) return 1;
#ifdef CLIENT_SUBNET
else if(fptr == &msg_cache_sizefunc) return 1;
#endif
#ifdef USE_DNSCRYPT
else if(fptr == &dnsc_shared_secrets_sizefunc) return 1;
#endif
return 0;
}
@ -244,6 +247,9 @@ fptr_whitelist_hash_compfunc(lruhash_compfunc_type fptr)
else if(fptr == &rate_compfunc) return 1;
else if(fptr == &ip_rate_compfunc) return 1;
else if(fptr == &test_slabhash_compfunc) return 1;
#ifdef USE_DNSCRYPT
else if(fptr == &dnsc_shared_secrets_compfunc) return 1;
#endif
return 0;
}
@ -257,6 +263,9 @@ fptr_whitelist_hash_delkeyfunc(lruhash_delkeyfunc_type fptr)
else if(fptr == &rate_delkeyfunc) return 1;
else if(fptr == &ip_rate_delkeyfunc) return 1;
else if(fptr == &test_slabhash_delkey) return 1;
#ifdef USE_DNSCRYPT
else if(fptr == &dnsc_shared_secrets_delkeyfunc) return 1;
#endif
return 0;
}
@ -271,6 +280,9 @@ fptr_whitelist_hash_deldatafunc(lruhash_deldatafunc_type fptr)
else if(fptr == &test_slabhash_deldata) return 1;
#ifdef CLIENT_SUBNET
else if(fptr == &subnet_data_delete) return 1;
#endif
#ifdef USE_DNSCRYPT
else if(fptr == &dnsc_shared_secrets_deldatafunc) return 1;
#endif
return 0;
}