memcmp: Introduce and use consttime_memeq

[secnet.git] / site.c

diff --git a/site.c b/site.c
index a91c1be963567c2d732e22f8fa7e4e09a144e810..b9b4d0dd0c0974e3b5d960a077977e14c54d9349 100644 (file)
--- a/site.c
+++ b/site.c
@@ -266,7 +266,10 @@ struct site {
 
     /* The currently established session */
     struct data_key current;
+    struct data_key auxiliary_key;
+    bool_t auxiliary_is_new;
     uint64_t renegotiate_key_time; /* When we can negotiate a new key */
+    uint64_t auxiliary_renegotiate_key_time;
     transport_peers peers; /* Current address(es) of peer for data traffic */
 
     /* The current key setup protocol exchange.  We can only be
@@ -460,7 +463,7 @@ static bool_t check_msg(struct site *st, uint32_t type, struct msg *m,
        return False;
     }
     if (type==LABEL_MSG2) return True;
-    if (memcmp(m->nR,st->remoteN,NONCELEN)!=0) {
+    if (!consttime_memeq(m->nR,st->remoteN,NONCELEN)!=0) {
        *error="wrong remotely-generated nonce";
        return False;
     }
@@ -729,7 +732,7 @@ static bool_t process_msg6(struct site *st, struct buffer_if *msg6,
 
 static bool_t decrypt_msg0(struct site *st, struct buffer_if *msg0)
 {
-    cstring_t transform_err, newkey_err="n/a";
+    cstring_t transform_err, auxkey_err, newkey_err="n/a";
     struct msg0 m;
     uint32_t problem;
 
@@ -740,13 +743,41 @@ static bool_t decrypt_msg0(struct site *st, struct buffer_if *msg0)
 
     problem = st->current.transform->reverse(st->current.transform->st,
                                             msg0,&transform_err);
-    if (!problem) return True;
+    if (!problem) {
+       if (!st->auxiliary_is_new)
+           delete_one_key(st,&st->auxiliary_key,
+                          "peer has used new key","auxiliary key",LOG_SEC);
+       return True;
+    }
 
     if (problem==2) {
        slog(st,LOG_DROP,"transform: %s (merely skew)",transform_err);
        return False;
     }
 
+    buffer_copy(msg0, &st->scratch);
+    problem = st->auxiliary_key.transform->reverse
+       (st->auxiliary_key.transform->st,msg0,&auxkey_err);
+    if (problem==0) {
+       slog(st,LOG_DROP,"processing packet which uses auxiliary key");
+       if (st->auxiliary_is_new) {
+           /* We previously timed out in state SENTMSG5 but it turns
+            * out that our peer did in fact get our MSG5 and is
+            * using the new key.  So we should switch to it too. */
+           /* This is a bit like activate_new_key. */
+           struct data_key t;
+           t=st->current;
+           st->current=st->auxiliary_key;
+           st->auxiliary_key=t;
+
+           delete_one_key(st,&st->auxiliary_key,"peer has used new key",
+                          "previous key",LOG_SEC);
+           st->auxiliary_is_new=0;
+           st->renegotiate_key_time=st->auxiliary_renegotiate_key_time;
+       }
+       return True;
+    }
+
     if (st->state==SITE_SENTMSG5) {
        buffer_copy(msg0, &st->scratch);
        if (!st->new_transform->reverse(st->new_transform->st,
@@ -761,7 +792,8 @@ static bool_t decrypt_msg0(struct site *st, struct buffer_if *msg0)
        }
     }
 
-    slog(st,LOG_SEC,"transform: %s (new: %s)",transform_err,newkey_err);
+    slog(st,LOG_SEC,"transform: %s (aux: %s, new: %s)",
+        transform_err,auxkey_err,newkey_err);
     initiate_key_setup(st,"incoming message would not decrypt");
     return False;
 }
@@ -822,6 +854,24 @@ static bool_t send_msg(struct site *st)
        st->timeout=st->now+st->setup_retry_interval;
        st->retries--;
        return True;
+    } else if (st->state==SITE_SENTMSG5) {
+       slog(st,LOG_SETUP_TIMEOUT,"timed out sending MSG5, stashing new key");
+       /* We stash the key we have produced, in case it turns out that
+        * our peer did see our MSG5 after all and starts using it. */
+       /* This is a bit like some of activate_new_key */
+       struct transform_inst_if *t;
+       t=st->auxiliary_key.transform;
+       st->auxiliary_key.transform=st->new_transform;
+       st->new_transform=t;
+
+       t->delkey(t->st);
+       st->auxiliary_is_new=1;
+       st->auxiliary_key.key_timeout=st->now+st->key_lifetime;
+       st->auxiliary_renegotiate_key_time=st->now+st->key_renegotiate_time;
+       st->auxiliary_key.remote_session_id=st->setup_session_id;
+
+       enter_state_wait(st);
+       return False;
     } else {
        slog(st,LOG_SETUP_TIMEOUT,"timed out sending key setup packet "
            "(in state %s)",state_name(st->state));
@@ -877,14 +927,17 @@ static void activate_new_key(struct site *st)
 {
     struct transform_inst_if *t;
 
-    /* We have two transform instances, which we swap between active
-       and setup */
-    t=st->current.transform;
+    /* We have three transform instances, which we swap between old,
+       active and setup */
+    t=st->auxiliary_key.transform;
+    st->auxiliary_key.transform=st->current.transform;
     st->current.transform=st->new_transform;
     st->new_transform=t;
 
     t->delkey(t->st);
     st->timeout=0;
+    st->auxiliary_is_new=0;
+    st->auxiliary_key.key_timeout=st->current.key_timeout;
     st->current.key_timeout=st->now+st->key_lifetime;
     st->renegotiate_key_time=st->now+st->key_renegotiate_time;
     transport_peers_copy(st,&st->peers,&st->setup_peers);
@@ -911,6 +964,7 @@ static void delete_keys(struct site *st, cstring_t reason, uint32_t loglevel)
        delete_one_key(st,&st->current,0,0,0);
        set_link_quality(st);
     }
+    delete_one_key(st,&st->auxiliary_key,0,0,0);
 }
 
 static void state_assert(struct site *st, bool_t ok)
@@ -1096,6 +1150,7 @@ static int site_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
        active. */
     site_settimeout(st->timeout, timeout_io);
     site_settimeout(st->current.key_timeout, timeout_io);
+    site_settimeout(st->auxiliary_key.key_timeout, timeout_io);
 
     return 0; /* success */
 }
@@ -1127,6 +1182,7 @@ static void site_afterpoll(void *sst, struct pollfd *fds, int nfds)
        }
     }
     check_expiry(st,&st->current,"current key");
+    check_expiry(st,&st->auxiliary_key,"auxiliary key");
 }
 
 /* This function is called by the netlink device to deliver packets
@@ -1496,6 +1552,7 @@ static list_t *site_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->timeout=0;
 
     st->current.key_timeout=0;
+    st->auxiliary_key.key_timeout=0;
     transport_peers_clear(st,&st->peers);
     transport_peers_clear(st,&st->setup_peers);
     /* XXX mlock these */
@@ -1523,7 +1580,9 @@ static list_t *site_apply(closure_t *self, struct cloc loc, dict_t *context,
        st->comms[i]->request_notify(st->comms[i]->st, st, site_incoming);
 
     st->current.transform=st->transform->create(st->transform->st);
+    st->auxiliary_key.transform=st->transform->create(st->transform->st);
     st->new_transform=st->transform->create(st->transform->st);
+    st->auxiliary_is_new=0;
 
     enter_state_stop(st);