Applied with minor tweeks from Inga
On Wed, 2020-01-29 at 09:17 -0800, Brian Gix wrote:
> Re-arranged for efficientcy. Replay Protection was set up as an atomic
> check-and-add operation. Now we check the message early so we can
> discard it without taking further action, and only add it to the RPL
> once fully verified that it was authorized and addressed to us.
> ---
> mesh/model.c | 23 +++++++++----------
> mesh/net.c | 62 ++++++++++++++++++++++++++--------------------------
> mesh/net.h | 7 +++---
> 3 files changed, 45 insertions(+), 47 deletions(-)
>
> diff --git a/mesh/model.c b/mesh/model.c
> index 92a00496c..574b6621a 100644
> --- a/mesh/model.c
> +++ b/mesh/model.c
> @@ -964,10 +964,12 @@ bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,
> /* Unicast and not addressed to us */
> return false;
>
> - clear_text = l_malloc(size);
> - if (!clear_text)
> + /* Don't process if already in RPL */
> + crpl = node_get_crpl(node);
> + if (net_msg_check_replay_cache(net, src, crpl, seq, iv_index))
> return false;
>
> + clear_text = l_malloc(size);
> forward.data = clear_text;
>
> /*
> @@ -995,16 +997,6 @@ bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,
> goto done;
> }
>
> - /* print_packet("Clr Rx (pre-cache-check)", clear_text, size - 4); */
> -
> - crpl = node_get_crpl(node);
> -
> - if (net_msg_in_replay_cache(net, (uint16_t) decrypt_idx, src,
> - crpl, seq, iv_index)) {
> - result = true;
> - goto done;
> - }
> -
> print_packet("Clr Rx", clear_text, size - (szmict ? 8 : 4));
>
> forward.virt = decrypt_virt;
> @@ -1073,7 +1065,7 @@ bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,
> * Either the message has been processed internally or
> * has been passed on to an external model.
> */
> - result = forward.has_dst | forward.done;
> + result |= forward.has_dst | forward.done;
>
> /* If the message was to unicast address, we are done */
> if (!is_subscription && ele_idx == i)
> @@ -1088,8 +1080,13 @@ bool mesh_model_rx(struct mesh_node *node, bool szmict, uint32_t seq0,
> break;
> }
>
> + /* If this message handlable by us, add to RPL */
> + if (result)
> + net_msg_add_replay_cache(net, src, seq, iv_index);
> +
> done:
> l_free(clear_text);
> +
> return result;
> }
>
> diff --git a/mesh/net.c b/mesh/net.c
> index 19f3b87b7..d85df63da 100644
> --- a/mesh/net.c
> +++ b/mesh/net.c
> @@ -3759,9 +3759,8 @@ static bool clean_old_iv_index(void *a, void *b)
> return false;
> }
>
> -bool net_msg_in_replay_cache(struct mesh_net *net, uint16_t idx,
> - uint16_t src, uint16_t crpl, uint32_t seq,
> - uint32_t iv_index)
> +bool net_msg_check_replay_cache(struct mesh_net *net, uint16_t src,
> + uint16_t crpl, uint32_t seq, uint32_t iv_index)
> {
> struct mesh_rpl *rpe;
>
> @@ -3782,49 +3781,50 @@ bool net_msg_in_replay_cache(struct mesh_net *net, uint16_t idx,
> L_UINT_TO_PTR(src));
>
> if (rpe) {
> - if (iv_index > rpe->iv_index) {
> - rpe->seq = seq;
> - rpe->iv_index = iv_index;
> - rpl_put_entry(net->node, src, iv_index, seq);
> + if (iv_index > rpe->iv_index)
> return false;
> - }
> -
> - if (seq < rpe->seq) {
> - l_debug("Ignoring packet with lower sequence number");
> - return true;
> - }
>
> - if (seq == rpe->seq) {
> - l_debug("Message already processed (duplicate)");
> + /* return true if (iv_index | seq) too low */
> + if (iv_index < rpe->iv_index || seq <= rpe->seq) {
> + l_debug("Ignoring replayed packet");
> return true;
> }
> -
> - rpe->seq = seq;
> -
> - rpl_put_entry(net->node, src, iv_index, seq);
> -
> - return false;
> }
>
> - l_debug("New Entry for %4.4x", src);
> -
> - /* Replay Cache is fixed sized */
> - if (l_queue_length(net->replay_cache) >= crpl) {
> + /* SRC not in Replay Cache... see if there is space for it */
> + else if (l_queue_length(net->replay_cache) >= crpl) {
> int ret = l_queue_foreach_remove(net->replay_cache,
> clean_old_iv_index, L_UINT_TO_PTR(iv_index));
>
> + /* Return true if no space could be freed */
> if (!ret)
> return true;
> }
>
> - if (!rpl_put_entry(net->node, src, iv_index, seq))
> - return true;
> + return false;
> +}
> +
> +void net_msg_add_replay_cache(struct mesh_net *net, uint16_t src, uint32_t seq,
> + uint32_t iv_index)
> +{
> + struct mesh_rpl *rpe;
> +
> + if (!net || !net->node || !net->replay_cache)
> + return;
> +
> + rpe = l_queue_remove_if(net->replay_cache, match_replay_cache,
> + L_UINT_TO_PTR(src));
> +
> + if (!rpe) {
> + l_debug("New Entry for %4.4x", src);
> + rpe = l_new(struct mesh_rpl, 1);
> + rpe->seq = src;
> + }
>
> - rpe = l_new(struct mesh_rpl, 1);
> - rpe->src = src;
> rpe->seq = seq;
> rpe->iv_index = iv_index;
> - l_queue_push_head(net->replay_cache, rpe);
> + rpl_put_entry(net->node, src, iv_index, seq);
>
> - return false;
> + /* Optimize so that most recent conversations stay earliest in cache */
> + l_queue_push_head(net->replay_cache, rpe);
> }
> diff --git a/mesh/net.h b/mesh/net.h
> index ff0a9bb2b..6fedd69d7 100644
> --- a/mesh/net.h
> +++ b/mesh/net.h
> @@ -379,6 +379,7 @@ void mesh_net_set_prov(struct mesh_net *net, struct mesh_prov *prov);
> uint32_t mesh_net_get_instant(struct mesh_net *net);
> struct l_queue *mesh_net_get_friends(struct mesh_net *net);
> struct l_queue *mesh_net_get_negotiations(struct mesh_net *net);
> -bool net_msg_in_replay_cache(struct mesh_net *net, uint16_t idx,
> - uint16_t src, uint16_t crpl, uint32_t seq,
> - uint32_t iv_index);
> +bool net_msg_check_replay_cache(struct mesh_net *net, uint16_t src,
> + uint16_t crpl, uint32_t seq, uint32_t iv_index);
> +void net_msg_add_replay_cache(struct mesh_net *net, uint16_t src, uint32_t seq,
> + uint32_t iv_index);
