Re: [PATCH bpf-next v3 3/9] bpf: Add bpf_sock_addr_set() to allow writing sockaddr len from bpf

[Martin KaFai Lau <martin.lau@linux.dev>]

On 8/29/23 3:18 AM, Daan De Meyer wrote:
> +__bpf_kfunc int bpf_sock_addr_set_addr(struct bpf_sock_addr_kern *sa_kern,
> +				       const u8 *addr, u32 addrlen__sz)
> +{
> +	struct sockaddr *sa = sa_kern->uaddr;
> +	struct sockaddr_in *sa4;
> +	struct sockaddr_in6 *sa6;
> +	struct sockaddr_un *un;
> +
> +	switch (sa->sa_family) {

The sa_family could be AF_UNSPEC here for inet addr (eg. take a look at 
__inet_bind checking AF_UNSPEC). Test the sa_kern->sk->sk_family instead.

> +	case AF_INET:
> +		if (addrlen__sz != 4)
> +			return -EINVAL;
> +		sa4 = (struct sockaddr_in *)sa;
> +		sa4->sin_addr.s_addr = *(__be32 *)addr;
> +		break;
> +	case AF_INET6:
> +		if (addrlen__sz != 16)
> +			return -EINVAL;
> +		sa6 = (struct sockaddr_in6 *)sa;
> +		memcpy(sa6->sin6_addr.s6_addr, addr, 16);
> +		break;
> +	default:
> +		WARN_ON_ONCE(1);

The above switch case will test sk_family instead, so this WARN should never 
happen and should be removed.

> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
>   __diag_pop();