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tun: allow to attach ebpf socket filter 

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 by allowing either qemu or libvirt to
attach eBPF filter to tun.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2018-01-16 16:31:02 +08:00 committed by David S. Miller
parent cd5681d7d8
commit aff3d70a07
2 changed files with 35 additions and 4 deletions
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38
drivers/net/tun.c
View File

@ -239,6 +239,12 @@ 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;
};
struct veth {
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
};
bool tun_is_xdp_buff(void *ptr)
@ -1036,12 +1042,25 @@ 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]);
@ -1067,6 +1086,15 @@ 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);
/* Trim extra bytes since we may insert vlan proto & TCI
* in tun_put_user().
*/
len -= skb_vlan_tag_present(skb) ? sizeof(struct veth) : 0;
if (len <= 0 || pskb_trim(skb, len))
goto drop;
if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
goto drop;
@ -2054,10 +2082,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
if (vlan_hlen) {
int ret;
struct {
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
} veth;
struct veth veth;
veth.h_vlan_proto = skb->vlan_proto;
veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
@ -2225,6 +2250,7 @@ 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)
@ -3019,6 +3045,10 @@ 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;

1
include/uapi/linux/if_tun.h
View File

@ -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