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@@ -349,13 +349,19 @@ out:
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sock_put(sk);
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}
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-/* This routine computes an IPv4 DCCP checksum. */
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-void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
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+static inline u16 dccp_v4_csum_finish(struct sk_buff *skb,
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+ __be32 src, __be32 dst)
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+{
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+ return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
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+}
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+
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+void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
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{
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const struct inet_sock *inet = inet_sk(sk);
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struct dccp_hdr *dh = dccp_hdr(skb);
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- dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
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+ dccp_csum_outgoing(skb);
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+ dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
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}
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EXPORT_SYMBOL_GPL(dccp_v4_send_check);
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@@ -454,47 +460,6 @@ static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
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return sk;
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}
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-int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
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- const __be32 daddr)
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-{
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- const struct dccp_hdr* dh = dccp_hdr(skb);
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- int checksum_len;
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- u32 tmp;
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-
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- if (dh->dccph_cscov == 0)
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- checksum_len = skb->len;
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- else {
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- checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
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- checksum_len = checksum_len < skb->len ? checksum_len :
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- skb->len;
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- }
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-
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- tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
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- return csum_tcpudp_magic(saddr, daddr, checksum_len,
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- IPPROTO_DCCP, tmp);
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-}
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-
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-EXPORT_SYMBOL_GPL(dccp_v4_checksum);
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-
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-static int dccp_v4_verify_checksum(struct sk_buff *skb,
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- const __be32 saddr, const __be32 daddr)
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-{
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- struct dccp_hdr *dh = dccp_hdr(skb);
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- int checksum_len;
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- u32 tmp;
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-
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- if (dh->dccph_cscov == 0)
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- checksum_len = skb->len;
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- else {
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- checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
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- checksum_len = checksum_len < skb->len ? checksum_len :
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- skb->len;
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- }
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- tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
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- return csum_tcpudp_magic(saddr, daddr, checksum_len,
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- IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
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-}
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-
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static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
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struct sk_buff *skb)
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{
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@@ -536,8 +501,8 @@ static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
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const struct inet_request_sock *ireq = inet_rsk(req);
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struct dccp_hdr *dh = dccp_hdr(skb);
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- dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
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- ireq->rmt_addr);
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+ dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
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+ ireq->rmt_addr);
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memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
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err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
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ireq->rmt_addr,
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@@ -602,8 +567,9 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
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dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
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DCCP_SKB_CB(rxskb)->dccpd_seq);
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- dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
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- rxskb->nh.iph->daddr);
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+ dccp_csum_outgoing(skb);
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+ dh->dccph_checksum = dccp_v4_csum_finish(skb, rxskb->nh.iph->saddr,
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+ rxskb->nh.iph->daddr);
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bh_lock_sock(dccp_v4_ctl_socket->sk);
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err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
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@@ -779,6 +745,7 @@ EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
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int dccp_invalid_packet(struct sk_buff *skb)
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{
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const struct dccp_hdr *dh;
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+ unsigned int cscov;
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if (skb->pkt_type != PACKET_HOST)
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return 1;
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@@ -830,6 +797,22 @@ int dccp_invalid_packet(struct sk_buff *skb)
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return 1;
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}
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+ /*
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+ * If P.CsCov is too large for the packet size, drop packet and return.
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+ * This must come _before_ checksumming (not as RFC 4340 suggests).
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+ */
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+ cscov = dccp_csum_coverage(skb);
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+ if (cscov > skb->len) {
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+ LIMIT_NETDEBUG(KERN_WARNING
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+ "DCCP: P.CsCov %u exceeds packet length %d\n",
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+ dh->dccph_cscov, skb->len);
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+ return 1;
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+ }
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+
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+ /* If header checksum is incorrect, drop packet and return.
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+ * (This step is completed in the AF-dependent functions.) */
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+ skb->csum = skb_checksum(skb, 0, cscov, 0);
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+
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return 0;
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}
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@@ -840,16 +823,17 @@ static int dccp_v4_rcv(struct sk_buff *skb)
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{
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const struct dccp_hdr *dh;
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struct sock *sk;
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+ int min_cov;
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- /* Step 1: Check header basics: */
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+ /* Step 1: Check header basics */
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if (dccp_invalid_packet(skb))
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goto discard_it;
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- /* If the header checksum is incorrect, drop packet and return */
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- if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
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- skb->nh.iph->daddr) < 0) {
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- LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
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+ /* Step 1: If header checksum is incorrect, drop packet and return */
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+ if (dccp_v4_csum_finish(skb, skb->nh.iph->saddr, skb->nh.iph->daddr)) {
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+ LIMIT_NETDEBUG(KERN_WARNING
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+ "%s: dropped packet with invalid checksum\n",
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__FUNCTION__);
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goto discard_it;
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}
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@@ -905,6 +889,21 @@ static int dccp_v4_rcv(struct sk_buff *skb)
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goto no_dccp_socket;
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}
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+ /*
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+ * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
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+ * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
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+ * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
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+ */
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+ min_cov = dccp_sk(sk)->dccps_pcrlen;
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+ if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
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+ dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
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+ dh->dccph_cscov, min_cov);
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+ /* FIXME: "Such packets SHOULD be reported using Data Dropped
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+ * options (Section 11.7) with Drop Code 0, Protocol
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+ * Constraints." */
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+ goto discard_and_relse;
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+ }
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+
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if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
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goto discard_and_relse;
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nf_reset(skb);
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Gerrit Renker