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