[DCCP]: Factor out common code for generating Resets
This factors code common to dccp_v{4,6}_ctl_send_reset into a separate function,
and adds support for filling in the Data 1 ... Data 3 fields from RFC 4340, 5.6.
It is useful to have this separate, since the following Reset codes will always
be generated from the control socket rather than via dccp_send_reset:
* Code 3, "No Connection", cf. 8.3.1;
* Code 4, "Packet Error" (identification for Data 1 added);
* Code 5, "Option Error" (identification for Data 1..3 added, will be used later);
* Code 6, "Mandatory Error" (same as Option Error);
* Code 7, "Connection Refused" (what on Earth is the difference to "No Connection"?);
* Code 8, "Bad Service Code";
* Code 9, "Too Busy";
* Code 10, "Bad Init Cookie" (not used).
Code 0 is not recommended by the RFC, the following codes would be used in
dccp_send_reset() instead, since they all relate to an established DCCP connection:
* Code 1, "Closed";
* Code 2, "Aborted";
* Code 11, "Aggression Penalty" (12.3).
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
net/dccp/dccp.h | 2 ++
net/dccp/ipv4.c | 38 +++++---------------------------------
net/dccp/ipv6.c | 39 ++++++---------------------------------
net/dccp/output.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 65 insertions(+), 66 deletions(-)
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -298,6 +298,8 @@ extern unsigned int dccp_poll(struct fil
extern int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
int addr_len);
+extern struct sk_buff *
+ dccp_ctl_make_reset(struct socket *ctl, struct sk_buff *skb);
extern int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
extern void dccp_send_close(struct sock *sk, const int active);
extern int dccp_invalid_packet(struct sk_buff *skb);
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -331,6 +331,58 @@ struct sk_buff *dccp_make_response(struc
EXPORT_SYMBOL_GPL(dccp_make_response);
+/* answer offending packet in @rcv_skb with Reset from control socket @ctl */
+struct sk_buff *dccp_ctl_make_reset(struct socket *ctl, struct sk_buff *rcv_skb)
+{
+ struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh;
+ struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb);
+ const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
+ sizeof(struct dccp_hdr_ext) +
+ sizeof(struct dccp_hdr_reset);
+ struct dccp_hdr_reset *dhr;
+ struct sk_buff *skb;
+
+ skb = alloc_skb(ctl->sk->sk_prot->max_header, GFP_ATOMIC);
+ if (skb == NULL)
+ return NULL;
+
+ skb_reserve(skb, ctl->sk->sk_prot->max_header);
+
+ /* Swap the send and the receive. */
+ dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
+ dh->dccph_type = DCCP_PKT_RESET;
+ dh->dccph_sport = rxdh->dccph_dport;
+ dh->dccph_dport = rxdh->dccph_sport;
+ dh->dccph_doff = dccp_hdr_reset_len / 4;
+ dh->dccph_x = 1;
+
+ dhr = dccp_hdr_reset(skb);
+ dhr->dccph_reset_code = dcb->dccpd_reset_code;
+
+ switch (dcb->dccpd_reset_code) {
+ case DCCP_RESET_CODE_PACKET_ERROR:
+ dhr->dccph_reset_data[0] = rxdh->dccph_type;
+ break;
+ case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */
+ case DCCP_RESET_CODE_MANDATORY_ERROR:
+ memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3);
+ break;
+ }
+ /*
+ * From RFC 4340, 8.3.1:
+ * If P.ackno exists, set R.seqno := P.ackno + 1.
+ * Else set R.seqno := 0.
+ */
+ if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
+ dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1));
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq);
+
+ dccp_csum_outgoing(skb);
+ return skb;
+}
+
+EXPORT_SYMBOL_GPL(dccp_ctl_make_reset);
+
/* send Reset on established socket, to close or abort the connection */
int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
{
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -512,17 +512,12 @@ out:
static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
{
int err;
- struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
const struct iphdr *rxiph;
- const int dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
- sizeof(struct dccp_hdr_ext) +
- sizeof(struct dccp_hdr_reset);
struct sk_buff *skb;
struct dst_entry *dst;
- u64 seqno = 0;
/* Never send a reset in response to a reset. */
- if (rxdh->dccph_type == DCCP_PKT_RESET)
+ if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
return;
if (((struct rtable *)rxskb->dst)->rt_type != RTN_LOCAL)
@@ -532,37 +527,14 @@ static void dccp_v4_ctl_send_reset(struc
if (dst == NULL)
return;
- skb = alloc_skb(dccp_v4_ctl_socket->sk->sk_prot->max_header,
- GFP_ATOMIC);
+ skb = dccp_ctl_make_reset(dccp_v4_ctl_socket, rxskb);
if (skb == NULL)
goto out;
- /* Reserve space for headers. */
- skb_reserve(skb, dccp_v4_ctl_socket->sk->sk_prot->max_header);
- skb->dst = dst_clone(dst);
-
- dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
-
- /* Build DCCP header and checksum it. */
- dh->dccph_type = DCCP_PKT_RESET;
- dh->dccph_sport = rxdh->dccph_dport;
- dh->dccph_dport = rxdh->dccph_sport;
- dh->dccph_doff = dccp_hdr_reset_len / 4;
- dh->dccph_x = 1;
- dccp_hdr_reset(skb)->dccph_reset_code =
- DCCP_SKB_CB(rxskb)->dccpd_reset_code;
-
- /* See "8.3.1. Abnormal Termination" in RFC 4340 */
- if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
- seqno = ADD48(DCCP_SKB_CB(rxskb)->dccpd_ack_seq, 1);
-
- dccp_hdr_set_seq(dh, seqno);
- dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
-
- dccp_csum_outgoing(skb);
rxiph = ip_hdr(rxskb);
- dh->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
- rxiph->daddr);
+ dccp_hdr(skb)->dccph_checksum = dccp_v4_csum_finish(skb, rxiph->saddr,
+ rxiph->daddr);
+ skb->dst = dst_clone(dst);
bh_lock_sock(dccp_v4_ctl_socket->sk);
err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -301,50 +301,23 @@ static void dccp_v6_reqsk_destructor(str
static void dccp_v6_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
{
- struct dccp_hdr *rxdh = dccp_hdr(rxskb), *dh;
struct ipv6hdr *rxip6h;
- const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
- sizeof(struct dccp_hdr_ext) +
- sizeof(struct dccp_hdr_reset);
struct sk_buff *skb;
struct flowi fl;
- u64 seqno = 0;
- if (rxdh->dccph_type == DCCP_PKT_RESET)
+ if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
return;
if (!ipv6_unicast_destination(rxskb))
return;
- skb = alloc_skb(dccp_v6_ctl_socket->sk->sk_prot->max_header,
- GFP_ATOMIC);
+ skb = dccp_ctl_make_reset(dccp_v6_ctl_socket, rxskb);
if (skb == NULL)
return;
- skb_reserve(skb, dccp_v6_ctl_socket->sk->sk_prot->max_header);
-
- dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
-
- /* Swap the send and the receive. */
- dh->dccph_type = DCCP_PKT_RESET;
- dh->dccph_sport = rxdh->dccph_dport;
- dh->dccph_dport = rxdh->dccph_sport;
- dh->dccph_doff = dccp_hdr_reset_len / 4;
- dh->dccph_x = 1;
- dccp_hdr_reset(skb)->dccph_reset_code =
- DCCP_SKB_CB(rxskb)->dccpd_reset_code;
-
- /* See "8.3.1. Abnormal Termination" in RFC 4340 */
- if (DCCP_SKB_CB(rxskb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
- seqno = ADD48(DCCP_SKB_CB(rxskb)->dccpd_ack_seq, 1);
-
- dccp_hdr_set_seq(dh, seqno);
- dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), DCCP_SKB_CB(rxskb)->dccpd_seq);
-
- dccp_csum_outgoing(skb);
rxip6h = ipv6_hdr(rxskb);
- dh->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
- &rxip6h->daddr);
+ dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
+ &rxip6h->daddr);
memset(&fl, 0, sizeof(fl));
ipv6_addr_copy(&fl.fl6_dst, &rxip6h->saddr);
@@ -352,8 +325,8 @@ static void dccp_v6_ctl_send_reset(struc
fl.proto = IPPROTO_DCCP;
fl.oif = inet6_iif(rxskb);
- fl.fl_ip_dport = dh->dccph_dport;
- fl.fl_ip_sport = dh->dccph_sport;
+ fl.fl_ip_dport = dccp_hdr(skb)->dccph_dport;
+ fl.fl_ip_sport = dccp_hdr(skb)->dccph_sport;
security_skb_classify_flow(rxskb, &fl);
/* sk = NULL, but it is safe for now. RST socket required. */
-
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