mpls: In mpls_egress verify the packet length.
Reobert Shearman noticed that mpls_egress is failing to verify that the bytes to be examined are in fact present in the packet before mpls_egress reads those bytes. As suggested by David Miller reduce this to a single pskb_may_pull call so that we don't do unnecessary work in the fast path. Reported-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -92,9 +92,24 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
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* The strange cases if we choose to support them will require
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* The strange cases if we choose to support them will require
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* manual configuration.
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* manual configuration.
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*/
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*/
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struct iphdr *hdr4 = ip_hdr(skb);
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struct iphdr *hdr4;
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bool success = true;
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bool success = true;
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/* The IPv4 code below accesses through the IPv4 header
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* checksum, which is 12 bytes into the packet.
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* The IPv6 code below accesses through the IPv6 hop limit
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* which is 8 bytes into the packet.
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*
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* For all supported cases there should always be at least 12
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* bytes of packet data present. The IPv4 header is 20 bytes
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* without options and the IPv6 header is always 40 bytes
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* long.
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*/
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if (!pskb_may_pull(skb, 12))
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return false;
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/* Use ip_hdr to find the ip protocol version */
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hdr4 = ip_hdr(skb);
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if (hdr4->version == 4) {
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if (hdr4->version == 4) {
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skb->protocol = htons(ETH_P_IP);
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skb->protocol = htons(ETH_P_IP);
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csum_replace2(&hdr4->check,
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csum_replace2(&hdr4->check,
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