Commit 9a5cb797 authored by Gilad Sever's avatar Gilad Sever Committed by Daniel Borkmann
Browse files

bpf: Fix bpf socket lookup from tc/xdp to respect socket VRF bindings 



When calling bpf_sk_lookup_tcp(), bpf_sk_lookup_udp() or
bpf_skc_lookup_tcp() from tc/xdp ingress, VRF socket bindings aren't
respoected, i.e. unbound sockets are returned, and bound sockets aren't
found.

VRF binding is determined by the sdif argument to sk_lookup(), however
when called from tc the IP SKB control block isn't initialized and thus
inet{,6}_sdif() always returns 0.

Fix by calculating sdif for the tc/xdp flows by observing the device's
l3 enslaved state.

The cg/sk_skb hooking points which are expected to support
inet{,6}_sdif() pass sdif=-1 which makes __bpf_skc_lookup() use the
existing logic.

Fixes: 6acc9b43 ("bpf: Add helper to retrieve socket in BPF")
Signed-off-by: default avatarGilad Sever <gilad9366@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarShmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: default avatarEyal Birger <eyal.birger@gmail.com>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Cc: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/20230621104211.301902-4-gilad9366@gmail.com
parent 97fbfeb8

include/linux/netdevice.h

+9 −0
Original line number Diff line number Diff line
@@ -5090,6 +5090,15 @@ static inline bool netif_is_l3_slave(const struct net_device *dev) 
	return dev->priv_flags & IFF_L3MDEV_SLAVE;

}



static inline int dev_sdif(const struct net_device *dev)

{

#ifdef CONFIG_NET_L3_MASTER_DEV

	if (netif_is_l3_slave(dev))

		return dev->ifindex;

#endif

	return 0;

}



static inline bool netif_is_bridge_master(const struct net_device *dev)

{

	return dev->priv_flags & IFF_EBRIDGE;

net/core/filter.c

+39 −30
Original line number Diff line number Diff line
@@ -6568,12 +6568,11 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple, 
static struct sock *

__bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,

		 struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,

		 u64 flags)

		 u64 flags, int sdif)

{

	struct sock *sk = NULL;

	struct net *net;

	u8 family;

	int sdif;



	if (len == sizeof(tuple->ipv4))

		family = AF_INET;
@@ -6585,10 +6584,12 @@ __bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, 
	if (unlikely(flags || !((s32)netns_id < 0 || netns_id <= S32_MAX)))

		goto out;



	if (sdif < 0) {

		if (family == AF_INET)

			sdif = inet_sdif(skb);

		else

			sdif = inet6_sdif(skb);

	}



	if ((s32)netns_id < 0) {

		net = caller_net;
@@ -6608,10 +6609,11 @@ __bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, 
static struct sock *

__bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,

		struct net *caller_net, u32 ifindex, u8 proto, u64 netns_id,

		u64 flags)

		u64 flags, int sdif)

{

	struct sock *sk = __bpf_skc_lookup(skb, tuple, len, caller_net,

					   ifindex, proto, netns_id, flags);

					   ifindex, proto, netns_id, flags,

					   sdif);



	if (sk) {

		struct sock *sk2 = sk_to_full_sk(sk);
@@ -6651,7 +6653,7 @@ bpf_skc_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len, 
	}



	return __bpf_skc_lookup(skb, tuple, len, caller_net, ifindex, proto,

				netns_id, flags);

				netns_id, flags, -1);

}



static struct sock *
@@ -6743,12 +6745,13 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = { 
BPF_CALL_5(bpf_tc_skc_lookup_tcp, struct sk_buff *, skb,

	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(skb->dev);

	int ifindex = skb->dev->ifindex;

	struct net_device *dev = skb->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_skc_lookup(skb, tuple, len, caller_net,

					       ifindex, IPPROTO_TCP, netns_id,

					       flags);

					       flags, sdif);

}



static const struct bpf_func_proto bpf_tc_skc_lookup_tcp_proto = {
@@ -6766,12 +6769,13 @@ static const struct bpf_func_proto bpf_tc_skc_lookup_tcp_proto = { 
BPF_CALL_5(bpf_tc_sk_lookup_tcp, struct sk_buff *, skb,

	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(skb->dev);

	int ifindex = skb->dev->ifindex;

	struct net_device *dev = skb->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_sk_lookup(skb, tuple, len, caller_net,

					      ifindex, IPPROTO_TCP, netns_id,

					      flags);

					      flags, sdif);

}



static const struct bpf_func_proto bpf_tc_sk_lookup_tcp_proto = {
@@ -6789,12 +6793,13 @@ static const struct bpf_func_proto bpf_tc_sk_lookup_tcp_proto = { 
BPF_CALL_5(bpf_tc_sk_lookup_udp, struct sk_buff *, skb,

	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(skb->dev);

	int ifindex = skb->dev->ifindex;

	struct net_device *dev = skb->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_sk_lookup(skb, tuple, len, caller_net,

					      ifindex, IPPROTO_UDP, netns_id,

					      flags);

					      flags, sdif);

}



static const struct bpf_func_proto bpf_tc_sk_lookup_udp_proto = {
@@ -6826,12 +6831,13 @@ static const struct bpf_func_proto bpf_sk_release_proto = { 
BPF_CALL_5(bpf_xdp_sk_lookup_udp, struct xdp_buff *, ctx,

	   struct bpf_sock_tuple *, tuple, u32, len, u32, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(ctx->rxq->dev);

	int ifindex = ctx->rxq->dev->ifindex;

	struct net_device *dev = ctx->rxq->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_sk_lookup(NULL, tuple, len, caller_net,

					      ifindex, IPPROTO_UDP, netns_id,

					      flags);

					      flags, sdif);

}



static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = {
@@ -6849,12 +6855,13 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = { 
BPF_CALL_5(bpf_xdp_skc_lookup_tcp, struct xdp_buff *, ctx,

	   struct bpf_sock_tuple *, tuple, u32, len, u32, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(ctx->rxq->dev);

	int ifindex = ctx->rxq->dev->ifindex;

	struct net_device *dev = ctx->rxq->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_skc_lookup(NULL, tuple, len, caller_net,

					       ifindex, IPPROTO_TCP, netns_id,

					       flags);

					       flags, sdif);

}



static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = {
@@ -6872,12 +6879,13 @@ static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = { 
BPF_CALL_5(bpf_xdp_sk_lookup_tcp, struct xdp_buff *, ctx,

	   struct bpf_sock_tuple *, tuple, u32, len, u32, netns_id, u64, flags)

{

	struct net *caller_net = dev_net(ctx->rxq->dev);

	int ifindex = ctx->rxq->dev->ifindex;

	struct net_device *dev = ctx->rxq->dev;

	int ifindex = dev->ifindex, sdif = dev_sdif(dev);

	struct net *caller_net = dev_net(dev);



	return (unsigned long)__bpf_sk_lookup(NULL, tuple, len, caller_net,

					      ifindex, IPPROTO_TCP, netns_id,

					      flags);

					      flags, sdif);

}



static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
@@ -6897,7 +6905,8 @@ BPF_CALL_5(bpf_sock_addr_skc_lookup_tcp, struct bpf_sock_addr_kern *, ctx, 
{

	return (unsigned long)__bpf_skc_lookup(NULL, tuple, len,

					       sock_net(ctx->sk), 0,

					       IPPROTO_TCP, netns_id, flags);

					       IPPROTO_TCP, netns_id, flags,

					       -1);

}



static const struct bpf_func_proto bpf_sock_addr_skc_lookup_tcp_proto = {
@@ -6916,7 +6925,7 @@ BPF_CALL_5(bpf_sock_addr_sk_lookup_tcp, struct bpf_sock_addr_kern *, ctx, 
{

	return (unsigned long)__bpf_sk_lookup(NULL, tuple, len,

					      sock_net(ctx->sk), 0, IPPROTO_TCP,

					      netns_id, flags);

					      netns_id, flags, -1);

}



static const struct bpf_func_proto bpf_sock_addr_sk_lookup_tcp_proto = {
@@ -6935,7 +6944,7 @@ BPF_CALL_5(bpf_sock_addr_sk_lookup_udp, struct bpf_sock_addr_kern *, ctx, 
{

	return (unsigned long)__bpf_sk_lookup(NULL, tuple, len,

					      sock_net(ctx->sk), 0, IPPROTO_UDP,

					      netns_id, flags);

					      netns_id, flags, -1);

}



static const struct bpf_func_proto bpf_sock_addr_sk_lookup_udp_proto = {