This patch allows userspace to attach eBPF filter to tun. This will
allow to implement VM dataplane filtering in a more efficient way
compared to cBPF filter.
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
drivers/net/tun.c | 26 ++++++++++++++++++++++++++
include/uapi/linux/if_tun.h | 1 +
2 files changed, 27 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 0853829..6e9452b 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -238,6 +238,7 @@ struct tun_struct {
struct tun_pcpu_stats __percpu *pcpu_stats;
struct bpf_prog __rcu *xdp_prog;
struct tun_prog __rcu *steering_prog;
+ struct tun_prog __rcu *filter_prog;
};
static int tun_napi_receive(struct napi_struct *napi, int budget)
@@ -984,12 +985,25 @@ static void tun_automq_xmit(struct tun_struct *tun,
struct sk_buff *skb)
#endif
}
+static unsigned int run_ebpf_filter(struct tun_struct *tun,
+ struct sk_buff *skb,
+ int len)
+{
+ struct tun_prog *prog = rcu_dereference(tun->filter_prog);
+
+ if (prog)
+ len = bpf_prog_run_clear_cb(prog->prog, skb);
+
+ return len;
+}
+
/* Net device start xmit */
static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct tun_struct *tun = netdev_priv(dev);
int txq = skb->queue_mapping;
struct tun_file *tfile;
+ int len = skb->len;
rcu_read_lock();
tfile = rcu_dereference(tun->tfiles[txq]);
@@ -1015,9 +1029,16 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb,
struct net_device *dev)
sk_filter(tfile->socket.sk, skb))
goto drop;
+ len = run_ebpf_filter(tun, skb, len);
+ if (!len)
+ goto drop;
+
if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
goto drop;
+ if (pskb_trim(skb, len))
+ goto drop;
+
skb_tx_timestamp(skb);
/* Orphan the skb - required as we might hang on to it
@@ -2068,6 +2089,7 @@ static void tun_free_netdev(struct net_device *dev)
tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
__tun_set_ebpf(tun, &tun->steering_prog, NULL);
+ __tun_set_ebpf(tun, &tun->filter_prog, NULL);
}
static void tun_setup(struct net_device *dev)
@@ -2849,6 +2871,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned
int cmd,
ret = tun_set_ebpf(tun, &tun->steering_prog, argp);
break;
+ case TUNSETFILTEREBPF:
+ ret = tun_set_ebpf(tun, &tun->filter_prog, argp);
+ break;
+
default:
ret = -EINVAL;
break;
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index fb38c17..ee432cd 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -58,6 +58,7 @@
#define TUNSETVNETBE _IOW('T', 222, int)
#define TUNGETVNETBE _IOR('T', 223, int)
#define TUNSETSTEERINGEBPF _IOR('T', 224, int)
+#define TUNSETFILTEREBPF _IOR('T', 225, int)
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
--
2.7.4
