From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 5188cd44c55db3e92cd9e77a40b5baa7ed4340f7 ]
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@xxxxxxxxxxxxxxx>
Fixes: 916e4cf46d02 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
---
drivers/net/macvtap.c | 3 +++
drivers/net/tun.c | 6 +++++-
include/net/ipv6.h | 2 ++
net/ipv6/output_core.c | 38 ++++++++++++++++++++++++++++++++++++++
4 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index cc1242ef08e0..2b7d7d64b193 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -17,6 +17,7 @@
#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>
@@ -568,6 +569,8 @@ 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;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 08123d9df292..a2a4442c6bba 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -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>
@@ -1103,6 +1104,8 @@ 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) {
@@ -1123,6 +1126,8 @@ 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:
@@ -1153,7 +1158,6 @@ 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_rxhash(skb);
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 6b4956e4408f..ea97c94fbc7d 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -661,6 +661,8 @@ 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));
}
+extern void ipv6_proxy_select_ident(struct sk_buff *skb);
+
extern int ip6_dst_hoplimit(struct dst_entry *dst);
/*
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 798eb0f79078..4bd870af05d6 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -3,10 +3,48 @@
* not configured or static. These functions are needed by GSO/GRO implementation.
*/
#include <linux/export.h>
+#include <linux/random.h>
+#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/addrconf.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;
+ static bool done = false;
+ u32 hash, id;
+
+ addrs = skb_header_pointer(skb,
+ skb_network_offset(skb) +
+ offsetof(struct ipv6hdr, saddr),
+ sizeof(buf), buf);
+ if (!addrs)
+ return;
+
+ if (!done) {
+ get_random_bytes(&ip6_proxy_idents_hashrnd,
+ sizeof(ip6_proxy_idents_hashrnd));
+ done = true;
+ }
+
+ 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)
{
--
2.1.2
--
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