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sys/dev/if_wg/module/wg_noise.c

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/*
* Copyright (C) 2015-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright (C) 2019-2020 Matt Dunwoodie <ncon@noconroy.net>
*
* 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.
*/
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/param.h>
#include <sys/rwlock.h>
#include <sys/wg_noise.h>
#include <crypto/blake2s.h>
#include <crypto/curve25519.h>
#include <zinc/chacha20poly1305.h>
/* Private functions */
static struct noise_keypair *
noise_remote_keypair_allocate(struct noise_remote *);
static void
noise_remote_keypair_free(struct noise_remote *,
struct noise_keypair *);
static uint32_t noise_remote_handshake_index_get(struct noise_remote *);
static void noise_remote_handshake_index_drop(struct noise_remote *);
static uint64_t noise_counter_send(struct noise_counter *);
static int noise_counter_recv(struct noise_counter *, uint64_t);
static void noise_kdf(uint8_t *, uint8_t *, uint8_t *, const uint8_t *,
size_t, size_t, size_t, size_t,
const uint8_t [NOISE_HASH_SIZE]);
static int noise_mix_dh(
uint8_t [NOISE_HASH_SIZE],
uint8_t [NOISE_SYMMETRIC_SIZE],
const uint8_t [NOISE_KEY_SIZE],
const uint8_t [NOISE_KEY_SIZE]);
static int noise_mix_ss(
uint8_t ck[NOISE_HASH_SIZE],
uint8_t key[NOISE_SYMMETRIC_SIZE],
const uint8_t ss[NOISE_KEY_SIZE]);
static void noise_mix_hash(
uint8_t [NOISE_HASH_SIZE],
const uint8_t *,
size_t);
static void noise_mix_psk(
uint8_t [NOISE_HASH_SIZE],
uint8_t [NOISE_HASH_SIZE],
uint8_t [NOISE_SYMMETRIC_SIZE],
const uint8_t [NOISE_KEY_SIZE]);
static void noise_param_init(
uint8_t [NOISE_HASH_SIZE],
uint8_t [NOISE_HASH_SIZE],
const uint8_t [NOISE_KEY_SIZE]);
static void noise_msg_encrypt(uint8_t *, const uint8_t *, size_t,
uint8_t [NOISE_SYMMETRIC_SIZE],
uint8_t [NOISE_HASH_SIZE]);
static int noise_msg_decrypt(uint8_t *, const uint8_t *, size_t,
uint8_t [NOISE_SYMMETRIC_SIZE],
uint8_t [NOISE_HASH_SIZE]);
static void noise_msg_ephemeral(
uint8_t [NOISE_HASH_SIZE],
uint8_t [NOISE_HASH_SIZE],
const uint8_t src[NOISE_KEY_SIZE]);
static void noise_tai64n_now(uint8_t [NOISE_TIMESTAMP_SIZE]);
static int noise_timer_expired(struct timespec *, time_t, long);
/* Set/Get noise parameters */
void
noise_local_init(struct noise_local *l, struct noise_upcall *upcall)
{
bzero(l, sizeof(*l));
rw_init(&l->l_identity_lock, "noise_local_identity");
l->l_upcall = *upcall;
}
void
noise_local_lock_identity(struct noise_local *l)
{
rw_enter_write(&l->l_identity_lock);
}
void
noise_local_unlock_identity(struct noise_local *l)
{
rw_exit_write(&l->l_identity_lock);
}
int
noise_local_set_private(struct noise_local *l, uint8_t private[NOISE_KEY_SIZE])
{
memcpy(l->l_private, private, NOISE_KEY_SIZE);
curve25519_clamp_secret(l->l_private);
l->l_has_identity = curve25519_generate_public(l->l_public, private);
return l->l_has_identity ? 0 : ENXIO;
}
int
noise_local_keys(struct noise_local *l, uint8_t public[NOISE_KEY_SIZE],
uint8_t private[NOISE_KEY_SIZE])
{
int ret = 0;
rw_enter_read(&l->l_identity_lock);
if (l->l_has_identity) {
if (public != NULL)
memcpy(public, l->l_public, NOISE_KEY_SIZE);
if (private != NULL)
memcpy(private, l->l_private, NOISE_KEY_SIZE);
} else {
ret = ENXIO;
}
rw_exit_read(&l->l_identity_lock);
return ret;
}
void
noise_remote_init(struct noise_remote *r, const uint8_t public[NOISE_KEY_SIZE],
struct noise_local *l)
{
bzero(r, sizeof(*r));
memcpy(r->r_public, public, NOISE_KEY_SIZE);
rw_init(&r->r_handshake_lock, "noise_handshake");
rw_init(&r->r_keypair_lock, "noise_keypair");
SLIST_INSERT_HEAD(&r->r_unused_keypairs, &r->r_keypair[0], kp_entry);
SLIST_INSERT_HEAD(&r->r_unused_keypairs, &r->r_keypair[1], kp_entry);
SLIST_INSERT_HEAD(&r->r_unused_keypairs, &r->r_keypair[2], kp_entry);
ASSERT(l != NULL);
r->r_local = l;
rw_enter_write(&l->l_identity_lock);
noise_remote_precompute(r);
rw_exit_write(&l->l_identity_lock);
}
int
noise_remote_set_psk(struct noise_remote *r, const uint8_t psk[NOISE_PSK_SIZE])
{
int same;
rw_enter_write(&r->r_handshake_lock);
same = !timingsafe_bcmp(r->r_psk, psk, NOISE_PSK_SIZE);
if (!same) {
memcpy(r->r_psk, psk, NOISE_PSK_SIZE);
}
rw_exit_write(&r->r_handshake_lock);
return same ? EEXIST : 0;
}
int
noise_remote_keys(struct noise_remote *r, uint8_t public[NOISE_KEY_SIZE],
uint8_t psk[NOISE_PSK_SIZE])
{
static uint8_t null_psk[NOISE_PSK_SIZE];
int ret;
if (public != NULL)
memcpy(public, r->r_public, NOISE_KEY_SIZE);
rw_enter_read(&r->r_handshake_lock);
if (psk != NULL)
memcpy(psk, r->r_psk, NOISE_PSK_SIZE);
ret = timingsafe_bcmp(r->r_psk, null_psk, NOISE_PSK_SIZE);
rw_exit_read(&r->r_handshake_lock);
/* If r_psk != null_psk return 0, else ENOENT (no psk) */
return ret ? 0 : ENOENT;
}
void
noise_remote_precompute(struct noise_remote *r)
{
struct noise_local *l = r->r_local;
if (!l->l_has_identity)
bzero(r->r_ss, NOISE_KEY_SIZE);
else if (!curve25519(r->r_ss, l->l_private, r->r_public))
bzero(r->r_ss, NOISE_KEY_SIZE);
rw_enter_write(&r->r_handshake_lock);
noise_remote_handshake_index_drop(r);
explicit_bzero(&r->r_handshake, sizeof(r->r_handshake));
rw_exit_write(&r->r_handshake_lock);
}
/* Handshake functions */
int
noise_create_initiation(struct noise_remote *r, struct noise_initiation *init)
{
struct noise_handshake *hs = &r->r_handshake;
struct noise_local *l = r->r_local;
uint8_t key[NOISE_SYMMETRIC_SIZE];
int ret = EINVAL;
rw_enter_read(&l->l_identity_lock);
rw_enter_write(&r->r_handshake_lock);
if (!l->l_has_identity)
goto error;
noise_param_init(hs->hs_ck, hs->hs_hash, r->r_public);
/* e */
curve25519_generate_secret(hs->hs_e);
if (curve25519_generate_public(init->ue, hs->hs_e) == 0)
goto error;
noise_msg_ephemeral(hs->hs_ck, hs->hs_hash, init->ue);
/* es */
if (noise_mix_dh(hs->hs_ck, key, hs->hs_e, r->r_public) != 0)
goto error;
/* s */
noise_msg_encrypt(init->es, l->l_public,
NOISE_KEY_SIZE, key, hs->hs_hash);
/* ss */
if (noise_mix_ss(hs->hs_ck, key, r->r_ss) != 0)
goto error;
/* {t} */
noise_tai64n_now(init->ets);
noise_msg_encrypt(init->ets, init->ets,
NOISE_TIMESTAMP_SIZE, key, hs->hs_hash);
noise_remote_handshake_index_drop(r);
hs->hs_state = CREATED_INITIATION;
hs->hs_local_index = noise_remote_handshake_index_get(r);
init->s_idx = hs->hs_local_index;
ret = 0;
error:
rw_exit_write(&r->r_handshake_lock);
rw_exit_read(&l->l_identity_lock);
if (ret != 0)
explicit_bzero(init, sizeof(*init));
explicit_bzero(key, NOISE_SYMMETRIC_SIZE);
return ret;
}
int
noise_consume_initiation(struct noise_local *l, struct noise_remote **rp,
struct noise_initiation *init)
{
struct noise_remote *r;
struct noise_handshake hs;
uint8_t key[NOISE_SYMMETRIC_SIZE];
uint8_t r_public[NOISE_KEY_SIZE];
uint8_t timestamp[NOISE_TIMESTAMP_SIZE];
int ret = EINVAL;
rw_enter_read(&l->l_identity_lock);
if (!l->l_has_identity)
goto error;
noise_param_init(hs.hs_ck, hs.hs_hash, l->l_public);
/* e */
noise_msg_ephemeral(hs.hs_ck, hs.hs_hash, init->ue);
/* es */
if (noise_mix_dh(hs.hs_ck, key, l->l_private, init->ue) != 0)
goto error;
/* s */
if (noise_msg_decrypt(r_public, init->es,
NOISE_KEY_SIZE + NOISE_MAC_SIZE, key, hs.hs_hash) != 0)
goto error;
/* Lookup the remote we received from */
if ((r = l->l_upcall.u_remote_get(l->l_upcall.u_arg, r_public)) == NULL)
goto error;
/* ss */
if (noise_mix_ss(hs.hs_ck, key, r->r_ss) != 0)
goto error;
/* {t} */
if (noise_msg_decrypt(timestamp, init->ets,
NOISE_TIMESTAMP_SIZE + NOISE_MAC_SIZE, key, hs.hs_hash) != 0)
goto error;
hs.hs_state = CONSUMED_INITIATION;
hs.hs_local_index = 0;
hs.hs_remote_index = init->s_idx;
memcpy(hs.hs_e, init->ue, NOISE_KEY_SIZE);
/* We have successfully computed the same results, now we ensure that
* this is not an initiation replay, or a flood attack */
rw_enter_write(&r->r_handshake_lock);
/* Replay */
if (memcmp(timestamp, r->r_timestamp, NOISE_TIMESTAMP_SIZE) > 0)
memcpy(r->r_timestamp, timestamp, NOISE_TIMESTAMP_SIZE);
else
goto error_set;
/* Flood attack */
if (noise_timer_expired(&r->r_last_init, 0, REJECT_INTERVAL))
getnanouptime(&r->r_last_init);
else
goto error_set;
/* Ok, we're happy to accept this initiation now */
noise_remote_handshake_index_drop(r);
r->r_handshake = hs;
*rp = r;
ret = 0;
error_set:
rw_exit_write(&r->r_handshake_lock);
error:
rw_exit_read(&l->l_identity_lock);
explicit_bzero(key, NOISE_SYMMETRIC_SIZE);
explicit_bzero(&hs, sizeof(hs));
return ret;
}
int
noise_create_response(struct noise_remote *r, struct noise_response *resp)
{
struct noise_handshake *hs = &r->r_handshake;
uint8_t key[NOISE_SYMMETRIC_SIZE];
uint8_t e[NOISE_KEY_SIZE];
int ret = EINVAL;
rw_enter_read(&r->r_local->l_identity_lock);
rw_enter_write(&r->r_handshake_lock);
if (hs->hs_state != CONSUMED_INITIATION)
goto error;
/* e */
curve25519_generate_secret(e);
if (curve25519_generate_public(resp->ue, e) == 0)
goto error;
noise_msg_ephemeral(hs->hs_ck, hs->hs_hash, resp->ue);
/* ee */
if (noise_mix_dh(hs->hs_ck, NULL, e, hs->hs_e) != 0)
goto error;
/* se */
if (noise_mix_dh(hs->hs_ck, NULL, e, r->r_public) != 0)
goto error;
/* psk */
noise_mix_psk(hs->hs_ck, hs->hs_hash, key, r->r_psk);
/* {} */
noise_msg_encrypt(resp->en, NULL, 0, key, hs->hs_hash);
hs->hs_state = CREATED_RESPONSE;
hs->hs_local_index = noise_remote_handshake_index_get(r);
resp->r_idx = hs->hs_remote_index;
resp->s_idx = hs->hs_local_index;
ret = 0;
error:
rw_exit_write(&r->r_handshake_lock);
rw_exit_read(&r->r_local->l_identity_lock);
if (ret != 0)
explicit_bzero(resp, sizeof(*resp));
explicit_bzero(key, NOISE_SYMMETRIC_SIZE);
explicit_bzero(e, NOISE_KEY_SIZE);
return ret;
}
int
noise_consume_response(struct noise_remote *r, struct noise_response *resp)
{
struct noise_local *l = r->r_local;
struct noise_handshake hs;
uint8_t key[NOISE_SYMMETRIC_SIZE];
uint8_t preshared_key[NOISE_KEY_SIZE];
int ret = EINVAL;
rw_enter_read(&l->l_identity_lock);
if (!l->l_has_identity)
goto error;
rw_enter_read(&r->r_handshake_lock);
hs = r->r_handshake;
memcpy(preshared_key, r->r_psk, NOISE_PSK_SIZE);
rw_exit_read(&r->r_handshake_lock);
if (hs.hs_state != CREATED_INITIATION ||
hs.hs_local_index != resp->r_idx)
goto error;
/* e */
noise_msg_ephemeral(hs.hs_ck, hs.hs_hash, resp->ue);
/* ee */
if (noise_mix_dh(hs.hs_ck, NULL, hs.hs_e, resp->ue) != 0)
goto error;
/* se */
if (noise_mix_dh(hs.hs_ck, NULL, l->l_private, resp->ue) != 0)
goto error;
/* psk */
noise_mix_psk(hs.hs_ck, hs.hs_hash, key, preshared_key);
/* {} */
if (noise_msg_decrypt(NULL, resp->en,
0 + NOISE_MAC_SIZE, key, hs.hs_hash) != 0)
goto error;
hs.hs_remote_index = resp->s_idx;
rw_enter_write(&r->r_handshake_lock);
if (r->r_handshake.hs_state == hs.hs_state &&
r->r_handshake.hs_local_index == hs.hs_local_index) {
r->r_handshake = hs;
r->r_handshake.hs_state = CONSUMED_RESPONSE;
ret = 0;
}
rw_exit_write(&r->r_handshake_lock);
error:
rw_exit_read(&l->l_identity_lock);
explicit_bzero(&hs, sizeof(hs));
explicit_bzero(key, NOISE_SYMMETRIC_SIZE);
return ret;
}
int
noise_remote_begin_session(struct noise_remote *r)
{
struct noise_handshake *hs = &r->r_handshake;
struct noise_keypair kp, *next, *current, *previous;
rw_enter_write(&r->r_handshake_lock);
/* We now derive the keypair from the handshake */
if (hs->hs_state == CONSUMED_RESPONSE) {
kp.kp_is_initiator = 1;
noise_kdf(kp.kp_send, kp.kp_recv, NULL, NULL,
NOISE_SYMMETRIC_SIZE, NOISE_SYMMETRIC_SIZE, 0, 0,
hs->hs_ck);
} else if (hs->hs_state == CREATED_RESPONSE) {
kp.kp_is_initiator = 0;
noise_kdf(kp.kp_recv, kp.kp_send, NULL, NULL,
NOISE_SYMMETRIC_SIZE, NOISE_SYMMETRIC_SIZE, 0, 0,
hs->hs_ck);
} else {
rw_exit_write(&r->r_keypair_lock);
return EINVAL;
}
kp.kp_valid = 1;
kp.kp_local_index = hs->hs_local_index;
kp.kp_remote_index = hs->hs_remote_index;
getnanouptime(&kp.kp_birthdate);
bzero(&kp.kp_ctr, sizeof(kp.kp_ctr));
rw_init(&kp.kp_ctr.c_lock, "noise_counter");
/* Now we need to add_new_keypair */
rw_enter_write(&r->r_keypair_lock);
next = r->r_next;
current = r->r_current;
previous = r->r_previous;
if (kp.kp_is_initiator) {
if (next != NULL) {
r->r_next = NULL;
r->r_previous = next;
noise_remote_keypair_free(r, current);
} else {
r->r_previous = current;
}
noise_remote_keypair_free(r, previous);
r->r_current = noise_remote_keypair_allocate(r);
*r->r_current = kp;
} else {
noise_remote_keypair_free(r, next);
r->r_previous = NULL;
noise_remote_keypair_free(r, previous);
r->r_next = noise_remote_keypair_allocate(r);
*r->r_next = kp;
}
rw_exit_write(&r->r_keypair_lock);
explicit_bzero(&r->r_handshake, sizeof(r->r_handshake));
rw_exit_write(&r->r_handshake_lock);
explicit_bzero(&kp, sizeof(kp));
return 0;
}
void
noise_remote_clear(struct noise_remote *r)
{
rw_enter_write(&r->r_handshake_lock);
noise_remote_handshake_index_drop(r);
explicit_bzero(&r->r_handshake, sizeof(r->r_handshake));
rw_exit_write(&r->r_handshake_lock);
rw_enter_write(&r->r_keypair_lock);
noise_remote_keypair_free(r, r->r_next);
noise_remote_keypair_free(r, r->r_current);
noise_remote_keypair_free(r, r->r_previous);
rw_exit_write(&r->r_keypair_lock);
}
void
noise_remote_expire_current(struct noise_remote *r)
{
rw_enter_write(&r->r_keypair_lock);
if (r->r_next != NULL)
r->r_next->kp_valid = 0;
if (r->r_current != NULL)
r->r_current->kp_valid = 0;
rw_exit_write(&r->r_keypair_lock);
}
int
noise_remote_ready(struct noise_remote *r)
{
struct noise_keypair *kp;
int ret;
rw_enter_read(&r->r_keypair_lock);
/* kp_ctr isn't locked here, we're happy to accept a racy read. */
if ((kp = r->r_current) == NULL ||
!kp->kp_valid ||
noise_timer_expired(&kp->kp_birthdate, REJECT_AFTER_TIME, 0) ||
kp->kp_ctr.c_recv >= REJECT_AFTER_MESSAGES ||
kp->kp_ctr.c_send >= REJECT_AFTER_MESSAGES)
ret = EINVAL;
else
ret = 0;
rw_exit_read(&r->r_keypair_lock);
return ret;
}
int
noise_remote_encrypt(struct noise_remote *r, struct noise_data *data,
size_t len)
{
struct noise_keypair *kp;
uint64_t ctr;
int ret = EINVAL;
rw_enter_read(&r->r_keypair_lock);
if ((kp = r->r_current) == NULL)
goto error;
/* We confirm that our values are within our tolerances. We want:
* - a valid keypair
* - our keypair to be less than REJECT_AFTER_TIME seconds old
* - our receive counter to be less than REJECT_AFTER_MESSAGES
* - our send counter to be less than REJECT_AFTER_MESSAGES
*
* kp_ctr isn't locked here, we're happy to accept a racy read. */
if (!kp->kp_valid ||
noise_timer_expired(&kp->kp_birthdate, REJECT_AFTER_TIME, 0) ||
kp->kp_ctr.c_recv >= REJECT_AFTER_MESSAGES ||
((ctr = noise_counter_send(&kp->kp_ctr)) > REJECT_AFTER_MESSAGES))
goto error;
/* Ensure that our counter is little endian and then encrypt our
* payload. We encrypt into the same buffer, so the caller must ensure
* that buf has NOISE_MAC_SIZE bytes to store the MAC. The nonce and
* index are passed back out to the caller through the provided
* data pointer. */
data->nonce = htole64(ctr);
data->r_idx = kp->kp_remote_index;
chacha20poly1305_encrypt(data->buf, data->buf, len,
NULL, 0, data->nonce, kp->kp_send);
/* If our values are still within tolerances, but we are approaching
* the tolerances, we notify the caller with ESTALE that they should
* establish a new keypair. The current keypair can continue to be used
* until the tolerances are hit. We notify if:
* - our send counter is not less than REKEY_AFTER_MESSAGES
* - we're the initiator and our keypair is older than
* REKEY_AFTER_TIME seconds */
ret = ESTALE;
if (ctr >= REKEY_AFTER_MESSAGES)
goto error;
if (kp->kp_is_initiator &&
noise_timer_expired(&kp->kp_birthdate, REKEY_AFTER_TIME, 0))
goto error;
ret = 0;
error:
rw_exit_read(&r->r_keypair_lock);
return ret;
}
int
noise_remote_decrypt(struct noise_remote *r, struct noise_data *data,
size_t len)
{
struct noise_keypair *kp;
uint64_t ctr;
int ret = EINVAL;
/* We retrieve the keypair corresponding to the provided index. We
* attempt the current keypair first as that is most likely. We also
* want to make sure that the keypair is valid as it would be
* catastrophic to decrypt against a zero'ed keypair. */
rw_enter_read(&r->r_keypair_lock);
if (r->r_current != NULL && r->r_current->kp_local_index == data->r_idx) {
kp = r->r_current;
} else if (r->r_previous != NULL && r->r_previous->kp_local_index == data->r_idx) {
kp = r->r_previous;
} else if (r->r_next != NULL && r->r_next->kp_local_index == data->r_idx) {
kp = r->r_next;
} else {
goto error;
}
/* We confirm that our values are within our tolerances. These values
* are the same as the encrypt routine.
*
* kp_ctr isn't locked here, we're happy to accept a racy read. */
if (noise_timer_expired(&kp->kp_birthdate, REJECT_AFTER_TIME, 0) ||
kp->kp_ctr.c_send >= REJECT_AFTER_MESSAGES ||
kp->kp_ctr.c_recv >= REJECT_AFTER_MESSAGES)
goto error;
/* Ensure we've got the counter in host byte order, then decrypt,
* then validate the counter. We don't want to validate the counter
* before decrypting as we do not know the message is authentic prior
* to decryption. */
ctr = letoh64(data->nonce);
if (chacha20poly1305_decrypt(data->buf, data->buf, len,
NULL, 0, data->nonce, kp->kp_recv) == 0)
goto error;
if (noise_counter_recv(&kp->kp_ctr, ctr) != 0)
goto error;
/* If we've received the handshake confirming data packet then move the
* next keypair into current. If we do slide the next keypair in, then
* we skip the REKEY_AFTER_TIME_RECV check. This is safe to do as a
* data packet can't confirm a session that we are an INITIATOR of. */
if (kp == r->r_next) {
rw_exit_read(&r->r_keypair_lock);
rw_enter_write(&r->r_keypair_lock);
if (kp == r->r_next && kp->kp_local_index == data->r_idx) {
noise_remote_keypair_free(r, r->r_previous);
r->r_previous = r->r_current;
r->r_current = r->r_next;
r->r_next = NULL;
ret = ECONNRESET;
goto error;
}
rw_downgrade(&r->r_keypair_lock);
}
/* Similar to when we encrypt, we want to notify the caller when we
* are approaching our tolerances. We notify if:
* - we're the initiator and the current keypair is older than
* REKEY_AFTER_TIME_RECV seconds. */
ret = ESTALE;
kp = r->r_current;
if (kp->kp_is_initiator &&
noise_timer_expired(&kp->kp_birthdate, REKEY_AFTER_TIME_RECV, 0))
goto error;
ret = 0;
error:
rw_exit(&r->r_keypair_lock);
return ret;
}
/* Private functions - these should not be called outside this file under any
* circumstances. */
static struct noise_keypair *
noise_remote_keypair_allocate(struct noise_remote *r)
{
struct noise_keypair *kp;
kp = SLIST_FIRST(&r->r_unused_keypairs);
SLIST_REMOVE_HEAD(&r->r_unused_keypairs, kp_entry);
return kp;
}
static void
noise_remote_keypair_free(struct noise_remote *r, struct noise_keypair *kp)
{
struct noise_upcall *u = &r->r_local->l_upcall;
if (kp != NULL) {
SLIST_INSERT_HEAD(&r->r_unused_keypairs, kp, kp_entry);
u->u_index_drop(u->u_arg, kp->kp_local_index);
bzero(kp->kp_send, sizeof(kp->kp_send));
bzero(kp->kp_recv, sizeof(kp->kp_recv));
}
}
static uint32_t
noise_remote_handshake_index_get(struct noise_remote *r)
{
struct noise_upcall *u = &r->r_local->l_upcall;
return u->u_index_set(u->u_arg, r);
}
static void
noise_remote_handshake_index_drop(struct noise_remote *r)
{
struct noise_handshake *hs = &r->r_handshake;
struct noise_upcall *u = &r->r_local->l_upcall;
rw_assert(&r->r_handshake_lock, RA_WLOCKED);
if (hs->hs_state != HS_ZEROED)
u->u_index_drop(u->u_arg, hs->hs_local_index);
}
static uint64_t
noise_counter_send(struct noise_counter *ctr)
{
uint64_t ret;
rw_enter_write(&ctr->c_lock);
ret = ctr->c_send++;
rw_exit_write(&ctr->c_lock);
return ret;
}
static int
noise_counter_recv(struct noise_counter *ctr, uint64_t recv)
{
uint64_t i, top, index_recv, index_ctr;
COUNTER_TYPE bit;
int ret = EEXIST;
rw_enter_write(&ctr->c_lock);
/* Check that the recv counter is valid */
if (ctr->c_recv >= REJECT_AFTER_MESSAGES ||
recv >= REJECT_AFTER_MESSAGES)
goto error;
/* If the packet is out of the window, invalid */
if (recv + COUNTER_WINDOW_SIZE < ctr->c_recv)
goto error;
/* If the new counter is ahead of the current counter, we'll need to
* zero out the bitmap that has previously been used */
index_recv = recv / COUNTER_TYPE_BITS;
index_ctr = ctr->c_recv / COUNTER_TYPE_BITS;
if (recv > ctr->c_recv) {
top = MIN(index_recv - index_ctr, COUNTER_TYPE_NUM);
for (i = 1; i <= top; i++)
ctr->c_backtrack[
(i + index_ctr) & (COUNTER_TYPE_NUM - 1)] = 0;
ctr->c_recv = recv;
}
index_recv %= COUNTER_TYPE_NUM;
bit = ((COUNTER_TYPE)1) << (recv % COUNTER_TYPE_BITS);
if (ctr->c_backtrack[index_recv] & bit)
goto error;
ctr->c_backtrack[index_recv] |= bit;
ret = 0;
error:
rw_exit_write(&ctr->c_lock);
return ret;
}
static void
noise_kdf(uint8_t *a, uint8_t *b, uint8_t *c, const uint8_t *x,
size_t a_len, size_t b_len, size_t c_len, size_t x_len,
const uint8_t ck[NOISE_HASH_SIZE])
{
uint8_t out[BLAKE2S_HASH_SIZE + 1];
uint8_t sec[BLAKE2S_HASH_SIZE];
ASSERT(a_len <= BLAKE2S_HASH_SIZE && b_len <= BLAKE2S_HASH_SIZE &&
c_len <= BLAKE2S_HASH_SIZE);
ASSERT(!(b || b_len || c || c_len) || (a && a_len));
ASSERT(!(c || c_len) || (b && b_len));
/* Extract entropy from "x" into sec */
blake2s_hmac(sec, x, ck, BLAKE2S_HASH_SIZE, x_len, NOISE_HASH_SIZE);
if (a == NULL || a_len == 0)
goto out;
/* Expand first key: key = sec, data = 0x1 */
out[0] = 1;
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, 1, BLAKE2S_HASH_SIZE);
memcpy(a, out, a_len);
if (b == NULL || b_len == 0)
goto out;
/* Expand second key: key = sec, data = "a" || 0x2 */
out[BLAKE2S_HASH_SIZE] = 2;
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, BLAKE2S_HASH_SIZE + 1,
BLAKE2S_HASH_SIZE);
memcpy(b, out, b_len);
if (c == NULL || c_len == 0)
goto out;
/* Expand third key: key = sec, data = "b" || 0x3 */
out[BLAKE2S_HASH_SIZE] = 3;
blake2s_hmac(out, out, sec, BLAKE2S_HASH_SIZE, BLAKE2S_HASH_SIZE + 1,
BLAKE2S_HASH_SIZE);
memcpy(c, out, c_len);
out:
/* Clear sensitive data from stack */
explicit_bzero(sec, BLAKE2S_HASH_SIZE);
explicit_bzero(out, BLAKE2S_HASH_SIZE + 1);
}
static int
noise_mix_dh(uint8_t ck[NOISE_HASH_SIZE], uint8_t key[NOISE_SYMMETRIC_SIZE],
const uint8_t private[NOISE_KEY_SIZE],
const uint8_t public[NOISE_KEY_SIZE])
{
uint8_t dh[NOISE_KEY_SIZE];
if (!curve25519(dh, private, public))
return EINVAL;
noise_kdf(ck, key, NULL, dh,
NOISE_HASH_SIZE, NOISE_SYMMETRIC_SIZE, 0, NOISE_KEY_SIZE, ck);
explicit_bzero(dh, NOISE_KEY_SIZE);
return 0;
}
static int
noise_mix_ss(uint8_t ck[NOISE_HASH_SIZE], uint8_t key[NOISE_SYMMETRIC_SIZE],
const uint8_t ss[NOISE_KEY_SIZE])
{
static uint8_t null_point[NOISE_KEY_SIZE];
if (timingsafe_bcmp(ss, null_point, NOISE_KEY_SIZE) == 0)
return ENOENT;
noise_kdf(ck, key, NULL, ss,
NOISE_HASH_SIZE, NOISE_SYMMETRIC_SIZE, 0, NOISE_KEY_SIZE, ck);
return 0;
}
static void
noise_mix_hash(uint8_t hash[NOISE_HASH_SIZE], const uint8_t *src,
size_t src_len)
{
struct blake2s_state blake;
blake2s_init(&blake, NOISE_HASH_SIZE);
blake2s_update(&blake, hash, NOISE_HASH_SIZE);
blake2s_update(&blake, src, src_len);
blake2s_final(&blake, hash, NOISE_HASH_SIZE);
}
static void
noise_mix_psk(uint8_t ck[NOISE_HASH_SIZE], uint8_t hash[NOISE_HASH_SIZE],
uint8_t key[NOISE_SYMMETRIC_SIZE], const uint8_t psk[NOISE_KEY_SIZE])
{
uint8_t tmp[NOISE_HASH_SIZE];
noise_kdf(ck, tmp, key, psk,
NOISE_HASH_SIZE, NOISE_HASH_SIZE, NOISE_SYMMETRIC_SIZE,
NOISE_PSK_SIZE, ck);
noise_mix_hash(hash, tmp, NOISE_HASH_SIZE);
explicit_bzero(tmp, NOISE_HASH_SIZE);
}
static void
noise_param_init(uint8_t ck[NOISE_HASH_SIZE], uint8_t hash[NOISE_HASH_SIZE],
const uint8_t s[NOISE_KEY_SIZE])
{
struct blake2s_state blake;
blake2s(ck, (uint8_t *)NOISE_HANDSHAKE_NAME, NULL,
NOISE_HASH_SIZE, strlen(NOISE_HANDSHAKE_NAME), 0);
blake2s_init(&blake, NOISE_HASH_SIZE);
blake2s_update(&blake, ck, NOISE_HASH_SIZE);
blake2s_update(&blake, (uint8_t *)NOISE_IDENTIFIER_NAME,
strlen(NOISE_IDENTIFIER_NAME));
blake2s_final(&blake, hash, NOISE_HASH_SIZE);
noise_mix_hash(hash, s, NOISE_KEY_SIZE);
}
static void
noise_msg_encrypt(uint8_t *dst, const uint8_t *src, size_t src_len,
uint8_t key[NOISE_SYMMETRIC_SIZE], uint8_t hash[NOISE_HASH_SIZE])
{
/* Nonce always zero for Noise_IK */
chacha20poly1305_encrypt(dst, src, src_len,
hash, NOISE_HASH_SIZE, 0, key);
noise_mix_hash(hash, dst, src_len + NOISE_MAC_SIZE);
}
static int
noise_msg_decrypt(uint8_t *dst, const uint8_t *src, size_t src_len,
uint8_t key[NOISE_SYMMETRIC_SIZE], uint8_t hash[NOISE_HASH_SIZE])
{
/* Nonce always zero for Noise_IK */
if (!chacha20poly1305_decrypt(dst, src, src_len,
hash, NOISE_HASH_SIZE, 0, key))
return EINVAL;
noise_mix_hash(hash, src, src_len);
return 0;
}
static void
noise_msg_ephemeral(uint8_t ck[NOISE_HASH_SIZE], uint8_t hash[NOISE_HASH_SIZE],
const uint8_t src[NOISE_KEY_SIZE])
{
noise_mix_hash(hash, src, NOISE_KEY_SIZE);
noise_kdf(ck, NULL, NULL, src, NOISE_HASH_SIZE, 0, 0, NOISE_KEY_SIZE, ck);
}
static void
noise_tai64n_now(uint8_t output[NOISE_TIMESTAMP_SIZE])
{
struct timespec time;
getnanotime(&time);
/* Round down the nsec counter to limit precise timing leak. */
time.tv_nsec &= REJECT_INTERVAL_MASK;
/* https://cr.yp.to/libtai/tai64.html */
*(uint64_t *)output = htobe64(0x400000000000000aULL + time.tv_sec);
*(uint32_t *)(output + sizeof(uint64_t)) = htobe32(time.tv_nsec);
}
static int
noise_timer_expired(struct timespec *birthdate, time_t sec, long nsec)
{
struct timespec uptime;
struct timespec expire = { .tv_sec = sec, .tv_nsec = nsec };
/* We don't really worry about a zeroed birthdate, to avoid the extra
* check on every encrypt/decrypt. This does mean that r_last_init
* check may fail if getnanouptime is < REJECT_INTERVAL from 0. */
getnanouptime(&uptime);
timespecadd(birthdate, &expire, &expire);
return timespeccmp(&uptime, &expire, >) ? ETIMEDOUT : 0;
}