[DCCP]: calling dccp_v{4,6}_reqsk_send_ack is a BUG
This patch removes two functions, the send_ack functions of request_sock,
which are not called/used by the DCCP code. It is correct that these
functions are not called, below is a justification why calling these
functions (on a passive socket in the LISTEN/RESPOND state) would mean
a DCCP protocol violation.
A) Background: using request_sock in TCP:
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 7107885..8dd9f5a 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -193,52 +193,6 @@
} /* else let the usual retransmit timer handle it */
}
-static void dccp_v4_reqsk_send_ack(struct sk_buff *rxskb,
- struct request_sock *req)
-{
- int err;
- struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
- const u32 dccp_hdr_ack_len = sizeof(struct dccp_hdr) +
- sizeof(struct dccp_hdr_ext) +
- sizeof(struct dccp_hdr_ack_bits);
- struct sk_buff *skb;
-
- if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
- return;
-
- skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header, GFP_ATOMIC);
- if (skb == NULL)
- return;
-
- /* Reserve space for headers. */
- skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
- skb->dst = dst_clone(rxskb->dst);
-
- dh = dccp_zeroed_hdr(skb, dccp_hdr_ack_len);
-
- /* Build DCCP header and checksum it. */
- dh->dccph_type = DCCP_PKT_ACK;
- dh->dccph_sport = rxdh->dccph_dport;
- dh->dccph_dport = rxdh->dccph_sport;
- dh->dccph_doff = dccp_hdr_ack_len / 4;
- dh->dccph_x = 1;
-
- dccp_hdr_set_seq(dh, DCCP_SKB_CB(rxskb)->dccpd_ack_seq);
- dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
- DCCP_SKB_CB(rxskb)->dccpd_seq);
-
- bh_lock_sock(dccp_v4_ctl_socket->sk);
- err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
- rxskb->nh.iph->daddr,
- rxskb->nh.iph->saddr, NULL);
- bh_unlock_sock(dccp_v4_ctl_socket->sk);
-
- if (err == NET_XMIT_CN || err == 0) {
- DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
- DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
- }
-}
-
static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
struct dst_entry *dst)
{
@@ -1014,7 +968,7 @@
.family = PF_INET,
.obj_size = sizeof(struct dccp_request_sock),
.rtx_syn_ack = dccp_v4_send_response,
- .send_ack = dccp_v4_reqsk_send_ack,
+ .send_ack = dccp_reqsk_send_ack,
.destructor = dccp_v4_reqsk_destructor,
.send_reset = dccp_v4_ctl_send_reset,
};