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Diffstat (limited to 'net/dccp/ipv4.c')
-rw-r--r--net/dccp/ipv4.c105
1 files changed, 52 insertions, 53 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 91bffaa761a6..496112080f3d 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -349,13 +349,19 @@ out:
sock_put(sk);
}
-/* This routine computes an IPv4 DCCP checksum. */
-void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
+static inline u16 dccp_v4_csum_finish(struct sk_buff *skb,
+ __be32 src, __be32 dst)
+{
+ return csum_tcpudp_magic(src, dst, skb->len, IPPROTO_DCCP, skb->csum);
+}
+
+void dccp_v4_send_check(struct sock *sk, int unused, struct sk_buff *skb)
{
const struct inet_sock *inet = inet_sk(sk);
struct dccp_hdr *dh = dccp_hdr(skb);
- dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr, inet->daddr);
+ dccp_csum_outgoing(skb);
+ dh->dccph_checksum = dccp_v4_csum_finish(skb, inet->saddr, inet->daddr);
}
EXPORT_SYMBOL_GPL(dccp_v4_send_check);
@@ -454,47 +460,6 @@ static struct sock *dccp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
return sk;
}
-int dccp_v4_checksum(const struct sk_buff *skb, const __be32 saddr,
- const __be32 daddr)
-{
- const struct dccp_hdr* dh = dccp_hdr(skb);
- int checksum_len;
- u32 tmp;
-
- if (dh->dccph_cscov == 0)
- checksum_len = skb->len;
- else {
- checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
- checksum_len = checksum_len < skb->len ? checksum_len :
- skb->len;
- }
-
- tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
- return csum_tcpudp_magic(saddr, daddr, checksum_len,
- IPPROTO_DCCP, tmp);
-}
-
-EXPORT_SYMBOL_GPL(dccp_v4_checksum);
-
-static int dccp_v4_verify_checksum(struct sk_buff *skb,
- const __be32 saddr, const __be32 daddr)
-{
- struct dccp_hdr *dh = dccp_hdr(skb);
- int checksum_len;
- u32 tmp;
-
- if (dh->dccph_cscov == 0)
- checksum_len = skb->len;
- else {
- checksum_len = (dh->dccph_cscov + dh->dccph_x) * sizeof(u32);
- checksum_len = checksum_len < skb->len ? checksum_len :
- skb->len;
- }
- tmp = csum_partial((unsigned char *)dh, checksum_len, 0);
- return csum_tcpudp_magic(saddr, daddr, checksum_len,
- IPPROTO_DCCP, tmp) == 0 ? 0 : -1;
-}
-
static struct dst_entry* dccp_v4_route_skb(struct sock *sk,
struct sk_buff *skb)
{
@@ -536,8 +501,8 @@ static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
const struct inet_request_sock *ireq = inet_rsk(req);
struct dccp_hdr *dh = dccp_hdr(skb);
- dh->dccph_checksum = dccp_v4_checksum(skb, ireq->loc_addr,
- ireq->rmt_addr);
+ dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
+ ireq->rmt_addr);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
ireq->rmt_addr,
@@ -602,8 +567,9 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
dccp_hdr_set_ack(dccp_hdr_ack_bits(skb),
DCCP_SKB_CB(rxskb)->dccpd_seq);
- dh->dccph_checksum = dccp_v4_checksum(skb, rxskb->nh.iph->saddr,
- rxskb->nh.iph->daddr);
+ dccp_csum_outgoing(skb);
+ dh->dccph_checksum = dccp_v4_csum_finish(skb, rxskb->nh.iph->saddr,
+ rxskb->nh.iph->daddr);
bh_lock_sock(dccp_v4_ctl_socket->sk);
err = ip_build_and_send_pkt(skb, dccp_v4_ctl_socket->sk,
@@ -779,6 +745,7 @@ EXPORT_SYMBOL_GPL(dccp_v4_do_rcv);
int dccp_invalid_packet(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
+ unsigned int cscov;
if (skb->pkt_type != PACKET_HOST)
return 1;
@@ -830,6 +797,22 @@ int dccp_invalid_packet(struct sk_buff *skb)
return 1;
}
+ /*
+ * If P.CsCov is too large for the packet size, drop packet and return.
+ * This must come _before_ checksumming (not as RFC 4340 suggests).
+ */
+ cscov = dccp_csum_coverage(skb);
+ if (cscov > skb->len) {
+ LIMIT_NETDEBUG(KERN_WARNING
+ "DCCP: P.CsCov %u exceeds packet length %d\n",
+ dh->dccph_cscov, skb->len);
+ return 1;
+ }
+
+ /* If header checksum is incorrect, drop packet and return.
+ * (This step is completed in the AF-dependent functions.) */
+ skb->csum = skb_checksum(skb, 0, cscov, 0);
+
return 0;
}
@@ -840,16 +823,17 @@ static int dccp_v4_rcv(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
struct sock *sk;
+ int min_cov;
- /* Step 1: Check header basics: */
+ /* Step 1: Check header basics */
if (dccp_invalid_packet(skb))
goto discard_it;
- /* If the header checksum is incorrect, drop packet and return */
- if (dccp_v4_verify_checksum(skb, skb->nh.iph->saddr,
- skb->nh.iph->daddr) < 0) {
- LIMIT_NETDEBUG(KERN_WARNING "%s: incorrect header checksum\n",
+ /* Step 1: If header checksum is incorrect, drop packet and return */
+ if (dccp_v4_csum_finish(skb, skb->nh.iph->saddr, skb->nh.iph->daddr)) {
+ LIMIT_NETDEBUG(KERN_WARNING
+ "%s: dropped packet with invalid checksum\n",
__FUNCTION__);
goto discard_it;
}
@@ -905,6 +889,21 @@ static int dccp_v4_rcv(struct sk_buff *skb)
goto no_dccp_socket;
}
+ /*
+ * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
+ * o if MinCsCov = 0, only packets with CsCov = 0 are accepted
+ * o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
+ */
+ min_cov = dccp_sk(sk)->dccps_pcrlen;
+ if (dh->dccph_cscov && (min_cov == 0 || dh->dccph_cscov < min_cov)) {
+ dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
+ dh->dccph_cscov, min_cov);
+ /* FIXME: "Such packets SHOULD be reported using Data Dropped
+ * options (Section 11.7) with Drop Code 0, Protocol
+ * Constraints." */
+ goto discard_and_relse;
+ }
+
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
nf_reset(skb);
generated by cgit v1.2.3 (git 2.0.4) at 2024-06-11 23:14:36 +0000