* [PATCH net 1/2] drivers/net: Disable UFO through virtio
2014-10-27 4:17 [PATCH net 0/2] drivers/net,ipv6: Fix IPv6 fragment ID selection for virtio Ben Hutchings
@ 2014-10-27 4:22 ` Ben Hutchings
2014-10-27 4:45 ` Varka Bhadram
2014-10-27 4:23 ` [PATCH net 2/2] drivers/net,ipv6: Select IPv6 fragment idents for virtio UFO packets Ben Hutchings
1 sibling, 1 reply; 4+ messages in thread
From: Ben Hutchings @ 2014-10-27 4:22 UTC (permalink / raw)
To: netdev; +Cc: Hannes Frederic Sowa, virtualization
[-- Attachment #1.1: Type: text/plain, Size: 8525 bytes --]
IPv6 does not allow fragmentation by routers, so there is no
fragmentation ID in the fixed header. UFO for IPv6 requires the ID to
be passed separately, but there is no provision for this in the virtio
net protocol.
Until recently our software implementation of UFO/IPv6 generated a new
ID, but this was a bug. Now we will use ID=0 for any UFO/IPv6 packet
passed through a tap, which is even worse.
Unfortunately there is no distinction between UFO/IPv4 and v6
features, so disable UFO on taps and virtio_net completely until we
have a proper solution.
We cannot depend on VM managers respecting the tap feature flags, so
keep accepting UFO packets but log a warning the first time we do
this.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 916e4cf46d02 ("ipv6: reuse ip6_frag_id from ip6_ufo_append_data")
---
I hoped that turning off the UFO feature completely would work, but when
I used libvirt and QEMU on Debian stable I found they still advertised
UFO to the guest.
Ben.
drivers/net/macvtap.c | 13 +++++--------
drivers/net/tun.c | 18 ++++++++++--------
drivers/net/virtio_net.c | 23 +++++++++++++----------
3 files changed, 28 insertions(+), 26 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 65e2892..2aeaa61 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -65,7 +65,7 @@ static struct cdev macvtap_cdev;
static const struct proto_ops macvtap_socket_ops;
#define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \
- NETIF_F_TSO6 | NETIF_F_UFO)
+ NETIF_F_TSO6)
#define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG)
@@ -569,6 +569,8 @@ static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb,
gso_type = SKB_GSO_TCPV6;
break;
case VIRTIO_NET_HDR_GSO_UDP:
+ pr_warn_once("macvtap: %s: using disabled UFO feature; please fix this program\n",
+ current->comm);
gso_type = SKB_GSO_UDP;
break;
default:
@@ -614,8 +616,6 @@ static void macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
- else if (sinfo->gso_type & SKB_GSO_UDP)
- vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
else
BUG();
if (sinfo->gso_type & SKB_GSO_TCP_ECN)
@@ -950,9 +950,6 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg)
if (arg & TUN_F_TSO6)
feature_mask |= NETIF_F_TSO6;
}
-
- if (arg & TUN_F_UFO)
- feature_mask |= NETIF_F_UFO;
}
/* tun/tap driver inverts the usage for TSO offloads, where
@@ -963,7 +960,7 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg)
* When user space turns off TSO, we turn off GSO/LRO so that
* user-space will not receive TSO frames.
*/
- if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_UFO))
+ if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
features |= RX_OFFLOADS;
else
features &= ~RX_OFFLOADS;
@@ -1064,7 +1061,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
case TUNSETOFFLOAD:
/* let the user check for future flags */
if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
- TUN_F_TSO_ECN | TUN_F_UFO))
+ TUN_F_TSO_ECN))
return -EINVAL;
rtnl_lock();
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 186ce54..e8b949a 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -174,7 +174,7 @@ struct tun_struct {
struct net_device *dev;
netdev_features_t set_features;
#define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
- NETIF_F_TSO6|NETIF_F_UFO)
+ NETIF_F_TSO6)
int vnet_hdr_sz;
int sndbuf;
@@ -1149,8 +1149,17 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
break;
case VIRTIO_NET_HDR_GSO_UDP:
+ {
+ static bool warned;
+ if (!warned) {
+ warned = true;
+ netdev_warn(tun->dev,
+ "%s: using disabled UFO feature; please fix this program\n",
+ current->comm);
+ }
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
break;
+ }
default:
tun->dev->stats.rx_frame_errors++;
kfree_skb(skb);
@@ -1251,8 +1260,6 @@ static ssize_t tun_put_user(struct tun_struct *tun,
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
- else if (sinfo->gso_type & SKB_GSO_UDP)
- gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
else {
pr_err("unexpected GSO type: "
"0x%x, gso_size %d, hdr_len %d\n",
@@ -1762,11 +1769,6 @@ static int set_offload(struct tun_struct *tun, unsigned long arg)
features |= NETIF_F_TSO6;
arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
}
-
- if (arg & TUN_F_UFO) {
- features |= NETIF_F_UFO;
- arg &= ~TUN_F_UFO;
- }
}
/* This gives the user a way to test for new features in future by
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d75256bd..e9e269d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -491,8 +491,16 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
break;
case VIRTIO_NET_HDR_GSO_UDP:
+ {
+ static bool warned;
+ if (!warned) {
+ warned = true;
+ netdev_warn(dev,
+ "host using disabled UFO feature; please fix it\n");
+ }
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
break;
+ }
case VIRTIO_NET_HDR_GSO_TCPV6:
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
break;
@@ -881,8 +889,6 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
- else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
- hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
else
BUG();
if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
@@ -1705,7 +1711,7 @@ static int virtnet_probe(struct virtio_device *vdev)
dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
- dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
+ dev->hw_features |= NETIF_F_TSO
| NETIF_F_TSO_ECN | NETIF_F_TSO6;
}
/* Individual feature bits: what can host handle? */
@@ -1715,11 +1721,9 @@ static int virtnet_probe(struct virtio_device *vdev)
dev->hw_features |= NETIF_F_TSO6;
if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
dev->hw_features |= NETIF_F_TSO_ECN;
- if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
- dev->hw_features |= NETIF_F_UFO;
if (gso)
- dev->features |= dev->hw_features & (NETIF_F_ALL_TSO|NETIF_F_UFO);
+ dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
/* (!csum && gso) case will be fixed by register_netdev() */
}
if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
@@ -1757,8 +1761,7 @@ static int virtnet_probe(struct virtio_device *vdev)
/* If we can receive ANY GSO packets, we must allocate large ones. */
if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6) ||
- virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN) ||
- virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UFO))
+ virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN))
vi->big_packets = true;
if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
@@ -1952,9 +1955,9 @@ static struct virtio_device_id id_table[] = {
static unsigned int features[] = {
VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
- VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
+ VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_TSO6,
VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
- VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
+ VIRTIO_NET_F_GUEST_ECN,
VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
--
Ben Hutchings
Theory and practice are closer in theory than in practice.
- John Levine, moderator of comp.compilers
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_______________________________________________
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^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH net 2/2] drivers/net,ipv6: Select IPv6 fragment idents for virtio UFO packets
2014-10-27 4:17 [PATCH net 0/2] drivers/net,ipv6: Fix IPv6 fragment ID selection for virtio Ben Hutchings
2014-10-27 4:22 ` [PATCH net 1/2] drivers/net: Disable UFO through virtio Ben Hutchings
@ 2014-10-27 4:23 ` Ben Hutchings
1 sibling, 0 replies; 4+ messages in thread
From: Ben Hutchings @ 2014-10-27 4:23 UTC (permalink / raw)
To: netdev; +Cc: Hannes Frederic Sowa, virtualization
[-- Attachment #1.1: Type: text/plain, Size: 4671 bytes --]
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")
---
drivers/net/macvtap.c | 3 +++
drivers/net/tun.c | 6 +++++-
include/net/ipv6.h | 2 ++
net/ipv6/output_core.c | 34 ++++++++++++++++++++++++++++++++++
4 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 2aeaa61..6f226de 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -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;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e8b949a..f8356b0 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>
@@ -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) {
@@ -1158,6 +1161,8 @@ 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:
@@ -1188,7 +1193,6 @@ 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);
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 97f4720..4292929 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -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,
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);
--
Ben Hutchings
Theory and practice are closer in theory than in practice.
- John Levine, moderator of comp.compilers
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^ permalink raw reply related [flat|nested] 4+ messages in thread