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Message-ID: <ZEq47yhL58mceV3C@google.com>
Date: Thu, 27 Apr 2023 11:03:27 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: Gilad Sever <gilad9366@...il.com>
Cc: dsahern@...nel.org, martin.lau@...ux.dev, daniel@...earbox.net,
john.fastabend@...il.com, ast@...nel.org, andrii@...nel.org,
song@...nel.org, yhs@...com, kpsingh@...nel.org, haoluo@...gle.com,
jolsa@...nel.org, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, mykolal@...com,
shuah@...nel.org, hawk@...nel.org, joe@...d.net.nz,
eyal.birger@...il.com, shmulik.ladkani@...il.com,
bpf@...r.kernel.org, netdev@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: Re: [PATCH bpf,v3 3/4] bpf: fix bpf socket lookup from tc/xdp to
respect socket VRF bindings
On 04/26, Gilad Sever wrote:
> 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: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF")
> Reviewed-by: Shmulik Ladkani <shmulik.ladkani@...il.com>
> Reviewed-by: Eyal Birger <eyal.birger@...il.com>
> Signed-off-by: Gilad Sever <gilad9366@...il.com>
Acked-by: Stanislav Fomichev <sdf@...gle.com>
with one nit below
> ---
> v3: Rename bpf_l2_sdif() to dev_sdif() as suggested by Stanislav Fomichev
> ---
> net/core/filter.c | 63 +++++++++++++++++++++++++++++++----------------
> 1 file changed, 42 insertions(+), 21 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index f43f86fc1235..894913aaa29f 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -6529,12 +6529,11 @@ 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;
> @@ -6546,10 +6545,12 @@ __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 (family == AF_INET)
> - sdif = inet_sdif(skb);
> - else
> - sdif = inet6_sdif(skb);
> + if (sdif < 0) {
> + if (family == AF_INET)
> + sdif = inet_sdif(skb);
> + else
> + sdif = inet6_sdif(skb);
> + }
>
> if ((s32)netns_id < 0) {
> net = caller_net;
> @@ -6569,10 +6570,11 @@ __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);
> @@ -6612,7 +6614,7 @@ 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 *
> @@ -6701,15 +6703,25 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
> .arg5_type = ARG_ANYTHING,
> };
[..]
> +static int dev_sdif(const struct net_device *dev)
> +{
> +#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
> + if (netif_is_l3_slave(dev))
> + return dev->ifindex;
> +#endif
> + return 0;
> +}
nit: should this go into include/linux/netdevice.h?
> +
> 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 sdif = dev_sdif(skb->dev);
> int ifindex = skb->dev->ifindex;
>
> 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 = {
> @@ -6728,11 +6740,12 @@ 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 sdif = dev_sdif(skb->dev);
> int ifindex = skb->dev->ifindex;
>
> 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 = {
> @@ -6751,11 +6764,12 @@ 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 sdif = dev_sdif(skb->dev);
> int ifindex = skb->dev->ifindex;
>
> 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 = {
> @@ -6788,11 +6802,13 @@ 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 sdif = dev_sdif(dev);
> + int ifindex = dev->ifindex;
>
> 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 = {
> @@ -6811,11 +6827,13 @@ 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 sdif = dev_sdif(dev);
> + int ifindex = dev->ifindex;
>
> 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 = {
> @@ -6834,11 +6852,13 @@ 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 sdif = dev_sdif(dev);
> + int ifindex = dev->ifindex;
>
> 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 = {
> @@ -6858,7 +6878,8 @@ 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 = {
> @@ -6877,7 +6898,7 @@ 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 = {
> @@ -6896,7 +6917,7 @@ 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 = {
> --
> 2.34.1
>
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