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-rw-r--r--net/dccp/ackvec.c88
-rw-r--r--net/dccp/ackvec.h1
-rw-r--r--net/dccp/input.c4
-rw-r--r--net/dccp/options.c6
4 files changed, 93 insertions, 6 deletions
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index abaf241c..e9a0f66 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -92,6 +92,24 @@ int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum)
return 0;
}
+static struct dccp_ackvec_record *dccp_ackvec_lookup(struct list_head *av_list,
+ const u64 ackno)
+{
+ struct dccp_ackvec_record *avr;
+ /*
+ * Exploit that records are inserted in descending order of sequence
+ * number, start with the oldest record first. If @ackno is `before'
+ * the earliest ack_ackno, the packet is too old to be considered.
+ */
+ list_for_each_entry_reverse(avr, av_list, avr_node) {
+ if (avr->avr_ack_seqno == ackno)
+ return avr;
+ if (before48(ackno, avr->avr_ack_seqno))
+ break;
+ }
+ return NULL;
+}
+
/*
* Buffer index and length computation using modulo-buffersize arithmetic.
* Note that, as pointers move from right to left, head is `before' tail.
@@ -356,6 +374,76 @@ int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
return 0;
}
+/**
+ * dccp_ackvec_clear_state - Perform house-keeping / garbage-collection
+ * This routine is called when the peer acknowledges the receipt of Ack Vectors
+ * up to and including @ackno. While based on on section A.3 of RFC 4340, here
+ * are additional precautions to prevent corrupted buffer state. In particular,
+ * we use tail_ackno to identify outdated records; it always marks the earliest
+ * packet of group (2) in 11.4.2.
+ */
+void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno)
+ {
+ struct dccp_ackvec_record *avr, *next;
+ u8 runlen_now, eff_runlen;
+ s64 delta;
+
+ avr = dccp_ackvec_lookup(&av->av_records, ackno);
+ if (avr == NULL)
+ return;
+ /*
+ * Deal with outdated acknowledgments: this arises when e.g. there are
+ * several old records and the acks from the peer come in slowly. In
+ * that case we may still have records that pre-date tail_ackno.
+ */
+ delta = dccp_delta_seqno(av->av_tail_ackno, avr->avr_ack_ackno);
+ if (delta < 0)
+ goto free_records;
+ /*
+ * Deal with overlapping Ack Vectors: don't subtract more than the
+ * number of packets between tail_ackno and ack_ackno.
+ */
+ eff_runlen = delta < avr->avr_ack_runlen ? delta : avr->avr_ack_runlen;
+
+ runlen_now = dccp_ackvec_runlen(av->av_buf + avr->avr_ack_ptr);
+ /*
+ * The run length of Ack Vector cells does not decrease over time. If
+ * the run length is the same as at the time the Ack Vector was sent, we
+ * free the ack_ptr cell. That cell can however not be freed if the run
+ * length has increased: in this case we need to move the tail pointer
+ * backwards (towards higher indices), to its next-oldest neighbour.
+ */
+ if (runlen_now > eff_runlen) {
+
+ av->av_buf[avr->avr_ack_ptr] -= eff_runlen + 1;
+ av->av_buf_tail = __ackvec_idx_add(avr->avr_ack_ptr, 1);
+
+ /* This move may not have cleared the overflow flag. */
+ if (av->av_overflow)
+ av->av_overflow = (av->av_buf_head == av->av_buf_tail);
+ } else {
+ av->av_buf_tail = avr->avr_ack_ptr;
+ /*
+ * We have made sure that avr points to a valid cell within the
+ * buffer. This cell is either older than head, or equals head
+ * (empty buffer): in both cases we no longer have any overflow.
+ */
+ av->av_overflow = 0;
+ }
+
+ /*
+ * The peer has acknowledged up to and including ack_ackno. Hence the
+ * first packet in group (2) of 11.4.2 is the successor of ack_ackno.
+ */
+ av->av_tail_ackno = ADD48(avr->avr_ack_ackno, 1);
+
+free_records:
+ list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
+ list_del(&avr->avr_node);
+ kmem_cache_free(dccp_ackvec_record_slab, avr);
+ }
+}
+
int __init dccp_ackvec_init(void)
{
dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index 23880be..3f70081 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -117,6 +117,7 @@ extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
const u8 *value, const u8 len);
extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av);
static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
diff --git a/net/dccp/input.c b/net/dccp/input.c
index c7aeeba..f91cf5a 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -165,8 +165,8 @@ static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
struct dccp_sock *dp = dccp_sk(sk);
if (dp->dccps_hc_rx_ackvec != NULL)
- dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
- DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ dccp_ackvec_clear_state(dp->dccps_hc_rx_ackvec,
+ DCCP_SKB_CB(skb)->dccpd_ack_seq);
}
static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 5adeeed..7743df0 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -54,7 +54,6 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
struct dccp_sock *dp = dccp_sk(sk);
const struct dccp_hdr *dh = dccp_hdr(skb);
const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
- u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
unsigned char *opt_ptr = options;
const unsigned char *opt_end = (unsigned char *)dh +
@@ -133,9 +132,8 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
case DCCPO_ACK_VECTOR_1:
if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
break;
- if (dp->dccps_hc_rx_ackvec != NULL &&
- dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
- goto out_invalid_option;
+ dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk),
+ len);
break;
case DCCPO_TIMESTAMP:
if (len != 4)
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