@@ -442,6 +442,7 @@ static inline int dccp_ack_pending(const
inet_csk_ack_scheduled(sk);
}
+extern int dccp_feat_finalise_settings(struct dccp_sock *dp);
extern void dccp_feat_list_purge(struct list_head *fn_list);
extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
@@ -400,6 +400,166 @@ int dccp_feat_change(struct dccp_minisoc
EXPORT_SYMBOL_GPL(dccp_feat_change);
+/*
+ * Tracking features whose value depend on the choice of CCID
+ *
+ * This is designed with an extension in mind so that a list walk could be done
+ * before activating any features. However, the existing framework was found to
+ * work satisfactorily up until now, the automatic verification is left open.
+ * When adding new CCIDs, add a corresponding dependency table here.
+ */
+static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
+{
+ static const struct ccid_dependency ccid2_dependencies[2][2] = {
+ /*
+ * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
+ * feature and Send Ack Vector is an RX feature, `is_local'
+ * needs to be reversed.
+ */
+ { /* Dependencies of the receiver-side (remote) CCID2 */
+ {
+ .dependent_feat = DCCPF_SEND_ACK_VECTOR,
+ .is_local = true,
+ .is_mandatory = true,
+ .val = 1
+ },
+ { 0, 0, 0, 0 }
+ },
+ { /* Dependencies of the sender-side (local) CCID2 */
+ {
+ .dependent_feat = DCCPF_SEND_ACK_VECTOR,
+ .is_local = false,
+ .is_mandatory = true,
+ .val = 1
+ },
+ { 0, 0, 0, 0 }
+ }
+ };
+ static const struct ccid_dependency ccid3_dependencies[2][5] = {
+ { /*
+ * Dependencies of the receiver-side CCID3
+ */
+ { /* locally disable Ack Vectors */
+ .dependent_feat = DCCPF_SEND_ACK_VECTOR,
+ .is_local = true,
+ .is_mandatory = false,
+ .val = 0
+ },
+ { /* see below why Send Loss Event Rate is on */
+ .dependent_feat = DCCPF_SEND_LEV_RATE,
+ .is_local = true,
+ .is_mandatory = true,
+ .val = 1
+ },
+ { /* NDP Count is needed as per RFC 4342, 6.1.1 */
+ .dependent_feat = DCCPF_SEND_NDP_COUNT,
+ .is_local = false,
+ .is_mandatory = true,
+ .val = 1
+ },
+ { 0, 0, 0, 0 },
+ },
+ { /*
+ * CCID3 at the TX side: we request that the HC-receiver
+ * will not send Ack Vectors (they will be ignored, so
+ * Mandatory is not set); we enable Send Loss Event Rate
+ * (Mandatory since the implementation does not support
+ * the Loss Intervals option of RFC 4342, 8.6).
+ * The last two options are for peer's information only.
+ */
+ {
+ .dependent_feat = DCCPF_SEND_ACK_VECTOR,
+ .is_local = false,
+ .is_mandatory = false,
+ .val = 0
+ },
+ {
+ .dependent_feat = DCCPF_SEND_LEV_RATE,
+ .is_local = false,
+ .is_mandatory = true,
+ .val = 1
+ },
+ { /* this CCID does not support Ack Ratio */
+ .dependent_feat = DCCPF_ACK_RATIO,
+ .is_local = true,
+ .is_mandatory = false,
+ .val = 0
+ },
+ { /* tell receiver we are sending NDP counts */
+ .dependent_feat = DCCPF_SEND_NDP_COUNT,
+ .is_local = true,
+ .is_mandatory = false,
+ .val = 1
+ },
+ { 0, 0, 0, 0 }
+ }
+ };
+ switch (ccid) {
+ case DCCPC_CCID2:
+ return ccid2_dependencies[is_local];
+ case DCCPC_CCID3:
+ return ccid3_dependencies[is_local];
+ default:
+ return NULL;
+ }
+}
+
+/**
+ * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
+ * @fn: feature-negotiation list to update
+ * @id: CCID number to track
+ * @is_local: whether TX CCID (1) or RX CCID (0) is meant
+ * This function needs to be called after registering all other features.
+ */
+static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
+{
+ const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
+ int i, rc = (table == NULL);
+
+ for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
+ if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
+ rc = __feat_register_sp(fn, table[i].dependent_feat,
+ table[i].is_local,
+ table[i].is_mandatory,
+ &table[i].val, 1);
+ else
+ rc = __feat_register_nn(fn, table[i].dependent_feat,
+ table[i].is_mandatory,
+ table[i].val);
+ return rc;
+}
+
+/**
+ * dccp_feat_finalise_settings - Finalise settings before starting negotiation
+ * @dp: client or listening socket (settings will be inherited)
+ * This is called after all registrations (socket initialisation, sysctls, and
+ * sockopt calls), and before sending the first packet containing Change options
+ * (ie. client-Request or server-Response), to ensure internal consistency.
+ */
+int dccp_feat_finalise_settings(struct dccp_sock *dp)
+{
+ struct list_head *fn = &dp->dccps_featneg;
+ struct dccp_feat_entry *entry;
+ int i = 2, ccids[2] = { -1, -1 };
+
+ /*
+ * Propagating CCIDs:
+ * 1) not useful to propagate CCID settings if this host advertises more
+ * than one CCID: the choice of CCID may still change - if this is
+ * the client, or if this is the server and the client sends
+ * singleton CCID values.
+ * 2) since is that propagate_ccid changes the list, we defer changing
+ * the sorted list until after the traversal.
+ */
+ list_for_each_entry(entry, fn, node)
+ if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
+ ccids[entry->is_local] = entry->val.sp.vec[0];
+ while (i--)
+ if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
+ return -1;
+ return 0;
+}
+
static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
{
struct dccp_sock *dp = dccp_sk(sk);
@@ -469,6 +469,10 @@ int dccp_connect(struct sock *sk)
struct sk_buff *skb;
struct inet_connection_sock *icsk = inet_csk(sk);
+ /* do not connect if feature negotiation setup fails */
+ if (dccp_feat_finalise_settings(dccp_sk(sk)))
+ return -EPROTO;
+
dccp_connect_init(sk);
skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
@@ -278,6 +278,9 @@ static inline int dccp_listen_start(stru
struct dccp_sock *dp = dccp_sk(sk);
dp->dccps_role = DCCP_ROLE_LISTEN;
+ /* do not start to listen if feature negotiation setup fails */
+ if (dccp_feat_finalise_settings(dp))
+ return -EPROTO;
return inet_csk_listen_start(sk, backlog);
}