Re: [PATCH bpf-next] selftests: bpf: Less strict size check in sockopt_sk

[sdf@google.com]

On 01/25, Felix Maurer wrote:
> Originally, the kernel strictly checked the size of the optval in
> getsockopt(TCP_ZEROCOPY_RECEIVE) to be equal to sizeof(struct
> tcp_zerocopy_receive). With c8856c0514549, this was changed to allow
> optvals of different sizes.

> The bpf code in the sockopt_sk test was still performing the strict size
> check. This fix adapts the kernel behavior from c8856c0514549 in the
> selftest, i.e., just check if the required fields are there.

Looks good, thank you!

Reviewed-by: Stanislav Fomichev <sdf@google.com>

> Fixes: 9cacf81f81611 ("bpf: Remove extra lock_sock for  
> TCP_ZEROCOPY_RECEIVE")
> Signed-off-by: Felix Maurer <fmaurer@redhat.com>
> ---
>   tools/testing/selftests/bpf/progs/sockopt_sk.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)

> diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c  
> b/tools/testing/selftests/bpf/progs/sockopt_sk.c
> index d0298dccedcd..c8d810010a94 100644
> --- a/tools/testing/selftests/bpf/progs/sockopt_sk.c
> +++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
> @@ -72,7 +72,8 @@ int _getsockopt(struct bpf_sockopt *ctx)
>   		 * reasons.
>   		 */

> -		if (optval + sizeof(struct tcp_zerocopy_receive) > optval_end)
> +		/* Check that optval contains address (__u64) */
> +		if (optval + sizeof(__u64) > optval_end)
>   			return 0; /* bounds check */

>   		if (((struct tcp_zerocopy_receive *)optval)->address != 0)
> --
> 2.34.1