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drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets

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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: 916e4cf46d ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ben Hutchings 2014-10-30 18:27:17 +00:00 committed by David S. Miller
parent 3d0ad09412
commit 5188cd44c5
4 changed files with 44 additions and 1 deletions
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3
drivers/net/macvtap.c
View File

@ -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;

6
drivers/net/tun.c
View File

@ -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);

2
include/net/ipv6.h
View File

@ -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,

34
net/ipv6/output_core.c
View File

@ -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);