netdev - Re: [PATCH bpf 1/3] bpf, sockmap: Check for any of tcp_bpf

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Message-ID: <87lem2yavb.fsf@cloudflare.com>
Date:   Mon, 16 Jan 2023 12:27:10 +0100
From:   Jakub Sitnicki <jakub@...udflare.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Dan Carpenter <error27@...il.com>, oe-kbuild@...ts.linux.dev,
        netdev@...r.kernel.org, lkp@...el.com,
        oe-kbuild-all@...ts.linux.dev, kernel-team@...udflare.com,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        syzbot+04c21ed96d861dccc5cd@...kaller.appspotmail.com
Subject: Re: [PATCH bpf 1/3] bpf, sockmap: Check for any of tcp_bpf_prots
 when cloning a listener

On Mon, Jan 16, 2023 at 11:39 AM +01, Eric Dumazet wrote:
> We might add a generic helper to make all this a bit more clear ?
>
> +#define is_insidevar(PTR, VAR) (                       \
> +       ((void *)(PTR) <= (void *)(VAR)) &&             \
> +       ((void *)(PTR) <= (void *)(VAR) + sizeof(VAR)))
> +
>
>
> ...
>
> if (is_insidevar(prot, tcp_bpf_prots))
>      newsk->sk_prot = sk->sk_prot_creator;

Sure can do. Thanks for the suggestion. I adjusted it a bit:
 - added cast to char * so we don't offend -Wpointer-arith,
 - fixed the lower and upper bound check.

Final form would look like:

#define is_insidevar(ptr, var)						\
	((void *)(ptr) >= (void *)(var)) &&				\
	((void *)(ptr) <  (void *)((char *)(var) + sizeof(var)))

Not sure where to stuff it. I propose include/linux/util_macros.h.