Re: [PATCH bpf-next v2 2/5] bpf: Add ksock kfuncs

[Mahe Tardy <mahe.tardy@gmail.com>]

On Wed, Jul 22, 2026 at 11:27:32AM -0700, Stanislav Fomichev wrote:
> On 07/22, Mahe Tardy wrote:
> > Add BPF kfuncs that allow BPF LSM programs to create and use sockets for
> > sending data. This provides a mechanism for BPF programs to emit
> > telemetry. For this first patch set, it's restricted to SOCK_DGRAM
> > socket types with IPPROTO_UDP protocol but could be easily extended to
> > SOCK_STREAM and IPPROTO_TCP in the future.
> > 

[...]

> > +
> > +/**
> > + * struct bpf_ksock_addr_opts - BPF kernel socket address parameters
> > + * @family:	Address family: AF_INET or AF_INET6.
> > + * @reserved:	Must be zero. Reserved for future use.
> > + * @port:	Port in host byte order.
> > + * @scope_id:	IPv6 scope ID for scoped AF_INET6 addresses, or zero.
> > + *		Must be zero when family=AF_INET.
> > + * @ipv4_addr:	IPv4 address in network byte order. Used when family=AF_INET.
> > + * @ipv6_addr:	IPv6 address (16 bytes, network byte order). Used when family=AF_INET6.
> > + */
> > +struct bpf_ksock_addr_opts {
> > +	__u8 family;
> > +	__u8 reserved;
> > +	__u16 port;
> > +	__u32 scope_id;
> > +
> > +	union {
> > +		__be32 ipv4_addr;
> > +		__u32 ipv6_addr[4]; /* in6_addr; network order */
> > +	};
> > +};
> 
> Do you add these because of BTF type checking? Can we have something a bit
> more orthodox like:
> 
> union bpf_sockaddr {
> 	struct sockaddr_in sin;
> 	struct sockaddr_in6 sin6;
> };
> 
> ?
> 
> I hope we can just pass these to sock_create and make it do all the input
> checking..

Yeah probably, I didn't think about this too much. I inherited it from
the netpoll tentative where Daniel suggested to take inspiration from
the fib lookup helpers[^1], which made sense for the netpoll call. If we
can simplify this we can get rid of bpf_ksock_parse_addr(). Let me try.

[^1]: https://lore.kernel.org/bpf/4b64ecd8-eade-4676-822e-da73abe2421d@iogearbox.net/