40 lines
1.1 KiB
C
40 lines
1.1 KiB
C
#include <linux/export.h>
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#include <linux/skbuff.h>
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#include <net/ip.h>
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#include <net/ipv6.h>
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/* This function exists only for tap drivers that must support broken
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* clients requesting UFO without specifying an IPv6 fragment ID.
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*
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* This is similar to ipv6_select_ident() but we use an independent hash
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* seed to limit information leakage.
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*/
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void ipv6_proxy_select_ident(struct net *net, struct sk_buff *skb)
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{
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static u32 ip6_proxy_idents_hashrnd __read_mostly;
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static bool hashrnd_initialized = false;
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struct in6_addr buf[2];
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struct in6_addr *addrs;
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u32 hash, id;
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addrs = skb_header_pointer(skb,
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skb_network_offset(skb) +
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offsetof(struct ipv6hdr, saddr),
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sizeof(buf), buf);
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if (!addrs)
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return;
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if (unlikely(!hashrnd_initialized)) {
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hashrnd_initialized = true;
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get_random_bytes(&ip6_proxy_idents_hashrnd,
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sizeof(ip6_proxy_idents_hashrnd));
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}
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hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
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hash = __ipv6_addr_jhash(&addrs[0], hash);
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hash ^= net_hash_mix(net);
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id = ip_idents_reserve(hash, 1);
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skb_shinfo(skb)->ip6_frag_id = htonl(id);
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}
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EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
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