[NET]: Added GSO header verification
When GSO packets come from an untrusted source (e.g., a Xen guest domain),
we need to verify the header integrity before passing it to the hardware.
Since the first step in GSO is to verify the header, we can reuse that
code by adding a new bit to gso_type: SKB_GSO_DODGY. Packets with this
bit set can only be fed directly to devices with the corresponding bit
NETIF_F_GSO_ROBUST. If the device doesn't have that bit, then the skb
is fed to the GSO engine which will allow the packet to be sent to the
hardware if it passes the header check.
This patch changes the sg flag to a full features flag. The same method
can be used to implement TSO ECN support. We simply have to mark packets
with CWR set with SKB_GSO_ECN so that only hardware with a corresponding
NETIF_F_TSO_ECN can accept them. The GSO engine can either fully segment
the packet, or segment the first MTU and pass the rest to the hardware for
further segmentation.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 03cd755..84b0f0d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -315,6 +315,7 @@
#define NETIF_F_GSO_SHIFT 16
#define NETIF_F_TSO (SKB_GSO_TCPV4 << NETIF_F_GSO_SHIFT)
#define NETIF_F_UFO (SKB_GSO_UDPV4 << NETIF_F_GSO_SHIFT)
+#define NETIF_F_GSO_ROBUST (SKB_GSO_DODGY << NETIF_F_GSO_SHIFT)
#define NETIF_F_GEN_CSUM (NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
#define NETIF_F_ALL_CSUM (NETIF_F_IP_CSUM | NETIF_F_GEN_CSUM)
@@ -543,7 +544,8 @@
struct net_device *,
struct packet_type *,
struct net_device *);
- struct sk_buff *(*gso_segment)(struct sk_buff *skb, int sg);
+ struct sk_buff *(*gso_segment)(struct sk_buff *skb,
+ int features);
void *af_packet_priv;
struct list_head list;
};
@@ -968,7 +970,7 @@
extern int weight_p;
extern int netdev_set_master(struct net_device *dev, struct net_device *master);
extern int skb_checksum_help(struct sk_buff *skb, int inward);
-extern struct sk_buff *skb_gso_segment(struct sk_buff *skb, int sg);
+extern struct sk_buff *skb_gso_segment(struct sk_buff *skb, int features);
#ifdef CONFIG_BUG
extern void netdev_rx_csum_fault(struct net_device *dev);
#else
@@ -988,11 +990,16 @@
extern void linkwatch_run_queue(void);
+static inline int skb_gso_ok(struct sk_buff *skb, int features)
+{
+ int feature = skb_shinfo(skb)->gso_size ?
+ skb_shinfo(skb)->gso_type << NETIF_F_GSO_SHIFT : 0;
+ return (features & feature) != feature;
+}
+
static inline int netif_needs_gso(struct net_device *dev, struct sk_buff *skb)
{
- int feature = skb_shinfo(skb)->gso_type << NETIF_F_GSO_SHIFT;
- return skb_shinfo(skb)->gso_size &&
- (dev->features & feature) != feature;
+ return skb_gso_ok(skb, dev->features);
}
#endif /* __KERNEL__ */
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 16eef03..5fb72da 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -172,6 +172,9 @@
enum {
SKB_GSO_TCPV4 = 1 << 0,
SKB_GSO_UDPV4 = 1 << 1,
+
+ /* This indicates the skb is from an untrusted source. */
+ SKB_GSO_DODGY = 1 << 2,
};
/**
@@ -1299,7 +1302,7 @@
struct sk_buff *skb1, const u32 len);
extern void skb_release_data(struct sk_buff *skb);
-extern struct sk_buff *skb_segment(struct sk_buff *skb, int sg);
+extern struct sk_buff *skb_segment(struct sk_buff *skb, int features);
static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,
int len, void *buffer)
diff --git a/include/net/protocol.h b/include/net/protocol.h
index 3b6dc15..40b6b9c 100644
--- a/include/net/protocol.h
+++ b/include/net/protocol.h
@@ -36,7 +36,8 @@
struct net_protocol {
int (*handler)(struct sk_buff *skb);
void (*err_handler)(struct sk_buff *skb, u32 info);
- struct sk_buff *(*gso_segment)(struct sk_buff *skb, int sg);
+ struct sk_buff *(*gso_segment)(struct sk_buff *skb,
+ int features);
int no_policy;
};
diff --git a/include/net/tcp.h b/include/net/tcp.h
index ca3d38d..624921e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1086,7 +1086,7 @@
extern int tcp_v4_destroy_sock(struct sock *sk);
-extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg);
+extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features);
#ifdef CONFIG_PROC_FS
extern int tcp4_proc_init(void);
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 2afdc7c..f8dbcee 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -184,6 +184,6 @@
dev->set_mac_address = br_set_mac_address;
dev->priv_flags = IFF_EBRIDGE;
- dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
- | NETIF_F_HIGHDMA | NETIF_F_TSO | NETIF_F_NO_CSUM;
+ dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA |
+ NETIF_F_TSO | NETIF_F_NO_CSUM | NETIF_F_GSO_ROBUST;
}
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 07956ec..f55ef68 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -392,7 +392,8 @@
features &= feature;
}
- br->dev->features = features | checksum | NETIF_F_LLTX;
+ br->dev->features = features | checksum | NETIF_F_LLTX |
+ NETIF_F_GSO_ROBUST;
}
/* called with RTNL */
diff --git a/net/core/dev.c b/net/core/dev.c
index f1c52cb..4f20149 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1190,11 +1190,14 @@
/**
* skb_gso_segment - Perform segmentation on skb.
* @skb: buffer to segment
- * @sg: whether scatter-gather is supported on the target.
+ * @features: features for the output path (see dev->features)
*
* This function segments the given skb and returns a list of segments.
+ *
+ * It may return NULL if the skb requires no segmentation. This is
+ * only possible when GSO is used for verifying header integrity.
*/
-struct sk_buff *skb_gso_segment(struct sk_buff *skb, int sg)
+struct sk_buff *skb_gso_segment(struct sk_buff *skb, int features)
{
struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
struct packet_type *ptype;
@@ -1210,12 +1213,14 @@
rcu_read_lock();
list_for_each_entry_rcu(ptype, &ptype_base[ntohs(type) & 15], list) {
if (ptype->type == type && !ptype->dev && ptype->gso_segment) {
- segs = ptype->gso_segment(skb, sg);
+ segs = ptype->gso_segment(skb, features);
break;
}
}
rcu_read_unlock();
+ __skb_push(skb, skb->data - skb->mac.raw);
+
return segs;
}
@@ -1291,9 +1296,15 @@
{
struct net_device *dev = skb->dev;
struct sk_buff *segs;
+ int features = dev->features & ~(illegal_highdma(dev, skb) ?
+ NETIF_F_SG : 0);
- segs = skb_gso_segment(skb, dev->features & NETIF_F_SG &&
- !illegal_highdma(dev, skb));
+ segs = skb_gso_segment(skb, features);
+
+ /* Verifying header integrity only. */
+ if (!segs)
+ return 0;
+
if (unlikely(IS_ERR(segs)))
return PTR_ERR(segs);
@@ -1310,13 +1321,17 @@
if (netdev_nit)
dev_queue_xmit_nit(skb, dev);
- if (!netif_needs_gso(dev, skb))
- return dev->hard_start_xmit(skb, dev);
+ if (netif_needs_gso(dev, skb)) {
+ if (unlikely(dev_gso_segment(skb)))
+ goto out_kfree_skb;
+ if (skb->next)
+ goto gso;
+ }
- if (unlikely(dev_gso_segment(skb)))
- goto out_kfree_skb;
+ return dev->hard_start_xmit(skb, dev);
}
+gso:
do {
struct sk_buff *nskb = skb->next;
int rc;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6edbb90..dfef9ee 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1848,13 +1848,13 @@
/**
* skb_segment - Perform protocol segmentation on skb.
* @skb: buffer to segment
- * @sg: whether scatter-gather can be used for generated segments
+ * @features: features for the output path (see dev->features)
*
* This function performs segmentation on the given skb. It returns
* the segment at the given position. It returns NULL if there are
* no more segments to generate, or when an error is encountered.
*/
-struct sk_buff *skb_segment(struct sk_buff *skb, int sg)
+struct sk_buff *skb_segment(struct sk_buff *skb, int features)
{
struct sk_buff *segs = NULL;
struct sk_buff *tail = NULL;
@@ -1863,6 +1863,7 @@
unsigned int offset = doffset;
unsigned int headroom;
unsigned int len;
+ int sg = features & NETIF_F_SG;
int nfrags = skb_shinfo(skb)->nr_frags;
int err = -ENOMEM;
int i = 0;
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 461216b..8d15715 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1097,7 +1097,7 @@
EXPORT_SYMBOL(inet_sk_rebuild_header);
-static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int sg)
+static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct iphdr *iph;
@@ -1126,10 +1126,10 @@
rcu_read_lock();
ops = rcu_dereference(inet_protos[proto]);
if (ops && ops->gso_segment)
- segs = ops->gso_segment(skb, sg);
+ segs = ops->gso_segment(skb, features);
rcu_read_unlock();
- if (IS_ERR(segs))
+ if (!segs || unlikely(IS_ERR(segs)))
goto out;
skb = segs;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c04176b..0336422 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2145,7 +2145,7 @@
EXPORT_SYMBOL(compat_tcp_getsockopt);
#endif
-struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int sg)
+struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct tcphdr *th;
@@ -2166,10 +2166,14 @@
if (!pskb_may_pull(skb, thlen))
goto out;
+ segs = NULL;
+ if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST))
+ goto out;
+
oldlen = (u16)~skb->len;
__skb_pull(skb, thlen);
- segs = skb_segment(skb, sg);
+ segs = skb_segment(skb, features);
if (IS_ERR(segs))
goto out;