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SubjectRe: [PATCH bpf-next v2 1/2] bpf: Add ifindex to bpf_sk_lookup
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On 11/4/21 5:23 AM, Mark Pashmfouroush wrote:
> It may be helpful to have access to the ifindex during bpf socket
> lookup. An example may be to scope certain socket lookup logic to
> specific interfaces, i.e. an interface may be made exempt from custom
> lookup code.
>
> Add the ifindex of the arriving connection to the bpf_sk_lookup API.
>
> Signed-off-by: Mark Pashmfouroush <markpash@cloudflare.com>
>
> diff --git a/include/linux/filter.h b/include/linux/filter.h
> index 24b7ed2677af..0012a5176a32 100644
> --- a/include/linux/filter.h
> +++ b/include/linux/filter.h
> @@ -1374,6 +1374,7 @@ struct bpf_sk_lookup_kern {
> const struct in6_addr *daddr;
> } v6;
> struct sock *selected_sk;
> + u32 ifindex;

In struct __sk_buff, we have two ifindex related fields:

__u32 ingress_ifindex;
__u32 ifindex;

Does newly-added ifindex corresponds to skb->ingress_ifindex or
skb->ifindex? From comments:
> + __u32 ifindex; /* The arriving interface. Determined by inet_iif. */

looks like it corresponds to ingress? Should be use the name
ingress_ifindex to be consistent with __sk_buff?

> bool no_reuseport;
> };
>
> @@ -1436,7 +1437,7 @@ extern struct static_key_false bpf_sk_lookup_enabled;
> static inline bool bpf_sk_lookup_run_v4(struct net *net, int protocol,
> const __be32 saddr, const __be16 sport,
> const __be32 daddr, const u16 dport,
> - struct sock **psk)
> + const int ifindex, struct sock **psk)
> {
> struct bpf_prog_array *run_array;
> struct sock *selected_sk = NULL;
> @@ -1452,6 +1453,7 @@ static inline bool bpf_sk_lookup_run_v4(struct net *net, int protocol,
> .v4.daddr = daddr,
> .sport = sport,
> .dport = dport,
> + .ifindex = ifindex,
> };
> u32 act;
>
> @@ -1474,7 +1476,7 @@ static inline bool bpf_sk_lookup_run_v6(struct net *net, int protocol,
> const __be16 sport,
> const struct in6_addr *daddr,
> const u16 dport,
> - struct sock **psk)
> + const int ifindex, struct sock **psk)
> {
> struct bpf_prog_array *run_array;
> struct sock *selected_sk = NULL;
> @@ -1490,6 +1492,7 @@ static inline bool bpf_sk_lookup_run_v6(struct net *net, int protocol,
> .v6.daddr = daddr,
> .sport = sport,
> .dport = dport,
> + .ifindex = ifindex,
> };
> u32 act;
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index ba5af15e25f5..5b8618a4d485 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -6296,6 +6296,7 @@ struct bpf_sk_lookup {
> __u32 local_ip4; /* Network byte order */
> __u32 local_ip6[4]; /* Network byte order */
> __u32 local_port; /* Host byte order */
> + __u32 ifindex; /* The arriving interface. Determined by inet_iif. */
> };
[...]

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