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Commit 5188cd44 authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller
Browse files

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: default avatarBen Hutchings <ben@decadent.org.uk>
Fixes: 916e4cf4 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3d0ad094

drivers/net/macvtap.c

+3 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/idr.h>

#include <linux/fs.h>



#include <net/ipv6.h>

#include <net/net_namespace.h>

#include <net/rtnetlink.h>

#include <net/sock.h>
@@ -572,6 +573,8 @@ static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb, 
			pr_warn_once("macvtap: %s: using disabled UFO feature; please fix this program\n",

				     current->comm);

			gso_type = SKB_GSO_UDP;

			if (skb->protocol == htons(ETH_P_IPV6))

				ipv6_proxy_select_ident(skb);

			break;

		default:

			return -EINVAL;

drivers/net/tun.c

+5 −1
Original line number Diff line number Diff line
@@ -65,6 +65,7 @@ 
#include <linux/nsproxy.h>

#include <linux/virtio_net.h>

#include <linux/rcupdate.h>

#include <net/ipv6.h>

#include <net/net_namespace.h>

#include <net/netns/generic.h>

#include <net/rtnetlink.h>
@@ -1139,6 +1140,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
		break;

	}



	skb_reset_network_header(skb);



	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {

		pr_debug("GSO!\n");

		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
@@ -1159,6 +1162,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
					    current->comm);

			}

			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;

			if (skb->protocol == htons(ETH_P_IPV6))

				ipv6_proxy_select_ident(skb);

			break;

		}

		default:
@@ -1189,7 +1194,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;

	}



	skb_reset_network_header(skb);

	skb_probe_transport_header(skb, 0);



	rxhash = skb_get_hash(skb);

include/net/ipv6.h

+2 −0
Original line number Diff line number Diff line
@@ -671,6 +671,8 @@ static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_add 
	return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));

}



void ipv6_proxy_select_ident(struct sk_buff *skb);



int ip6_dst_hoplimit(struct dst_entry *dst);



static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,

net/ipv6/output_core.c

+34 −0
Original line number Diff line number Diff line
@@ -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);