drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets
UFO is now disabled on all drivers that work with virtio net headers,
but userland may try to send UFO/IPv6 packets anyway. Instead of
sending with ID=0, we should select identifiers on their behalf (as we
used to).
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 916e4cf46d02 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index fc24c39..97f41a3 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -3,11 +3,45 @@
* not configured or static. These functions are needed by GSO/GRO implementation.
*/
#include <linux/export.h>
+#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/addrconf.h>
#include <net/secure_seq.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.
+ *
+ * The network header must be set before calling this.
+ */
+void ipv6_proxy_select_ident(struct sk_buff *skb)
+{
+ static u32 ip6_proxy_idents_hashrnd __read_mostly;
+ 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;
+
+ net_get_random_once(&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);
+
int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
{
u16 offset = sizeof(struct ipv6hdr);
