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Commit e356d37a authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
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[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: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@ghostprotocols.net>
parent 9bf55cda

net/dccp/dccp.h

+2 −0
Original line number Diff line number Diff line
@@ -294,6 +294,8 @@ extern unsigned int dccp_poll(struct file *file, struct socket *sock, 
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);

net/dccp/ipv4.c

+5 −33
Original line number Diff line number Diff line
@@ -510,17 +510,12 @@ static int dccp_v4_send_response(struct sock *sk, struct request_sock *req, 
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)
@@ -530,37 +525,14 @@ static void dccp_v4_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 
	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,

	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,

net/dccp/ipv6.c

+6 −33
Original line number Diff line number Diff line
@@ -301,49 +301,22 @@ static void dccp_v6_reqsk_destructor(struct request_sock *req) 


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,

	dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,

							    &rxip6h->daddr);



	memset(&fl, 0, sizeof(fl));
@@ -352,8 +325,8 @@ static void dccp_v6_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb) 


	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. */

net/dccp/output.c

+52 −0
Original line number Diff line number Diff line
@@ -327,6 +327,58 @@ struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, 


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)

{