1 files changed, 167 insertions, 0 deletions

diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 933a0ecf8d46..069d8ffe4c6f 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -23,6 +23,171 @@
 
 #define DCCP_FEAT_SP_NOAGREE (-123)
 
+static const struct {
+        u8                      feat_num;               /* DCCPF_xxx */
+        enum dccp_feat_type     rxtx;                   /* RX or TX  */
+        enum dccp_feat_type     reconciliation;         /* SP or NN  */
+        u8                      default_value;          /* as in 6.4 */
+/*
+ *    Lookup table for location and type of features (from RFC 4340/4342)
+ *  +--------------------------+----+-----+----+----+---------+-----------+
+ *  | Feature                  | Location | Reconc. | Initial |  Section  |
+ *  |                          | RX | TX  | SP | NN |  Value  | Reference |
+ *  +--------------------------+----+-----+----+----+---------+-----------+
+ *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
+ *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
+ *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
+ *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
+ *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
+ *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
+ *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
+ *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
+ *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
+ *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
+ *  +--------------------------+----+-----+----+----+---------+-----------+
+ */
+} dccp_feat_table[] = {
+        { DCCPF_CCID,            FEAT_AT_TX, FEAT_SP, 2 },
+        { DCCPF_SHORT_SEQNOS,    FEAT_AT_TX, FEAT_SP, 0 },
+        { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
+        { DCCPF_ECN_INCAPABLE,   FEAT_AT_RX, FEAT_SP, 0 },
+        { DCCPF_ACK_RATIO,       FEAT_AT_TX, FEAT_NN, 2 },
+        { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
+        { DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0 },
+        { DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0 },
+        { DCCPF_DATA_CHECKSUM,   FEAT_AT_RX, FEAT_SP, 0 },
+        { DCCPF_SEND_LEV_RATE,   FEAT_AT_RX, FEAT_SP, 0 },
+};
+#define DCCP_FEAT_SUPPORTED_MAX         ARRAY_SIZE(dccp_feat_table)
+
+/**
+ * dccp_feat_index  -  Hash function to map feature number into array position
+ * Returns consecutive array index or -1 if the feature is not understood.
+ */
+static int dccp_feat_index(u8 feat_num)
+{
+        /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
+        if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
+                return feat_num - 1;
+
+        /*
+         * Other features: add cases for new feature types here after adding
+         * them to the above table.
+         */
+        switch (feat_num) {
+        case DCCPF_SEND_LEV_RATE:
+                        return DCCP_FEAT_SUPPORTED_MAX - 1;
+        }
+        return -1;
+}
+
+static u8 dccp_feat_type(u8 feat_num)
+{
+        int idx = dccp_feat_index(feat_num);
+
+        if (idx < 0)
+                return FEAT_UNKNOWN;
+        return dccp_feat_table[idx].reconciliation;
+}
+
+/* copy constructor, fval must not already contain allocated memory */
+static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
+{
+        fval->sp.len = len;
+        if (fval->sp.len > 0) {
+                fval->sp.vec = kmemdup(val, len, gfp_any());
+                if (fval->sp.vec == NULL) {
+                        fval->sp.len = 0;
+                        return -ENOBUFS;
+                }
+        }
+        return 0;
+}
+
+static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
+{
+        if (unlikely(val == NULL))
+                return;
+        if (dccp_feat_type(feat_num) == FEAT_SP)
+                kfree(val->sp.vec);
+        memset(val, 0, sizeof(*val));
+}
+
+static struct dccp_feat_entry *
+              dccp_feat_clone_entry(struct dccp_feat_entry const *original)
+{
+        struct dccp_feat_entry *new;
+        u8 type = dccp_feat_type(original->feat_num);
+
+        if (type == FEAT_UNKNOWN)
+                return NULL;
+
+        new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
+        if (new == NULL)
+                return NULL;
+
+        if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
+                                                      original->val.sp.vec,
+                                                      original->val.sp.len)) {
+                kfree(new);
+                return NULL;
+        }
+        return new;
+}
+
+static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
+{
+        if (entry != NULL) {
+                dccp_feat_val_destructor(entry->feat_num, &entry->val);
+                kfree(entry);
+        }
+}
+
+/*
+ * List management functions
+ *
+ * Feature negotiation lists rely on and maintain the following invariants:
+ * - each feat_num in the list is known, i.e. we know its type and default value
+ * - each feat_num/is_local combination is unique (old entries are overwritten)
+ * - SP values are always freshly allocated
+ * - list is sorted in increasing order of feature number (faster lookup)
+ */
+
+static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
+{
+        list_del(&entry->node);
+        dccp_feat_entry_destructor(entry);
+}
+
+void dccp_feat_list_purge(struct list_head *fn_list)
+{
+        struct dccp_feat_entry *entry, *next;
+
+        list_for_each_entry_safe(entry, next, fn_list, node)
+                dccp_feat_entry_destructor(entry);
+        INIT_LIST_HEAD(fn_list);
+}
+EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
+
+/* generate @to as full clone of @from - @to must not contain any nodes */
+int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
+{
+        struct dccp_feat_entry *entry, *new;
+
+        INIT_LIST_HEAD(to);
+        list_for_each_entry(entry, from, node) {
+                new = dccp_feat_clone_entry(entry);
+                if (new == NULL)
+                        goto cloning_failed;
+                list_add_tail(&new->node, to);
+        }
+        return 0;
+
+cloning_failed:
+        dccp_feat_list_purge(to);
+        return -ENOMEM;
+}
+
 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
                      u8 *val, u8 len, gfp_t gfp)
 {
@@ -639,6 +804,8 @@ const char *dccp_feat_name(const u8 feat)
         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
                 return feature_names[DCCPF_RESERVED];
 
+        if (feat ==  DCCPF_SEND_LEV_RATE)
+                return "Send Loss Event Rate";
         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
                 return "CCID-specific";