Example #1
0
File: ipv4.c Project: panyfx/ath
/**
 *	dccp_invalid_packet  -  check for malformed packets
 *	Implements RFC 4340, 8.5:  Step 1: Check header basics
 *	Packets that fail these checks are ignored and do not receive Resets.
 */
int dccp_invalid_packet(struct sk_buff *skb)
{
	const struct dccp_hdr *dh;
	unsigned int cscov;

	if (skb->pkt_type != PACKET_HOST)
		return 1;

	/* If the packet is shorter than 12 bytes, drop packet and return */
	if (!pskb_may_pull(skb, sizeof(struct dccp_hdr))) {
		DCCP_WARN("pskb_may_pull failed\n");
		return 1;
	}

	dh = dccp_hdr(skb);

	/* If P.type is not understood, drop packet and return */
	if (dh->dccph_type >= DCCP_PKT_INVALID) {
		DCCP_WARN("invalid packet type\n");
		return 1;
	}

	/*
	 * If P.Data Offset is too small for packet type, drop packet and return
	 */
	if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) {
		DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff);
		return 1;
	}
	/*
	 * If P.Data Offset is too too large for packet, drop packet and return
	 */
	if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) {
		DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff);
		return 1;
	}

	/*
	 * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet
	 * has short sequence numbers), drop packet and return
	 */
	if ((dh->dccph_type < DCCP_PKT_DATA    ||
	    dh->dccph_type > DCCP_PKT_DATAACK) && dh->dccph_x == 0)  {
		DCCP_WARN("P.type (%s) not Data || [Data]Ack, while P.X == 0\n",
			  dccp_packet_name(dh->dccph_type));
		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) {
		DCCP_WARN("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;
}
Example #2
0
static int dccp_cksum(netdissect_options *ndo, const struct ip *ip,
	const struct dccp_hdr *dh, u_int len)
{
	return nextproto4_cksum(ndo, ip, (const u_int8_t *)(void *)dh, len,
				dccp_csum_coverage(dh, len), IPPROTO_DCCP);
}
Example #3
0
static int dccp6_cksum(const struct ip6_hdr *ip6, const struct dccp_hdr *dh, u_int len)
{
	return nextproto6_cksum(ip6, (const u_int8_t *)(void *)dh, len,
				dccp_csum_coverage(dh, len), IPPROTO_DCCP);
}
Example #4
0
static uint16_t dccp6_cksum(netdissect_options *ndo, const struct ip6_hdr *ip6,
	const struct dccp_hdr *dh, u_int len)
{
	return nextproto6_cksum(ndo, ip6, (const uint8_t *)(const void *)dh, len,
				dccp_csum_coverage(ndo, dh, len), IPPROTO_DCCP);
}