From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
David Ahern <dsahern@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH bpf v2 1/3] bpf_redirect_neigh: Support supplying the nexthop as a helper parameter
Date: Tue, 20 Oct 2020 20:08:18 +0200 [thread overview]
Message-ID: <87v9f422jx.fsf@toke.dk> (raw)
In-Reply-To: <20201020093003.6e1c7fdb@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Jakub Kicinski <kuba@kernel.org> writes:
> On Tue, 20 Oct 2020 12:51:02 +0200 Toke Høiland-Jørgensen wrote:
>> diff --git a/include/linux/filter.h b/include/linux/filter.h
>> index 20fc24c9779a..ba9de7188cd0 100644
>> --- a/include/linux/filter.h
>> +++ b/include/linux/filter.h
>> @@ -607,12 +607,21 @@ struct bpf_skb_data_end {
>> void *data_end;
>> };
>>
>> +struct bpf_nh_params {
>> + u8 nh_family;
>> + union {
>> + __u32 ipv4_nh;
>> + struct in6_addr ipv6_nh;
>> + };
>> +};
>
>> @@ -4906,6 +4910,18 @@ struct bpf_fib_lookup {
>> __u8 dmac[6]; /* ETH_ALEN */
>> };
>>
>> +struct bpf_redir_neigh {
>> + /* network family for lookup (AF_INET, AF_INET6) */
>> + __u8 nh_family;
>> + /* avoid hole in struct - must be set to 0 */
>> + __u8 unused[3];
>> + /* network address of nexthop; skips fib lookup to find gateway */
>> + union {
>> + __be32 ipv4_nh;
>> + __u32 ipv6_nh[4]; /* in6_addr; network order */
>> + };
>> +};
>
> Isn't this backward? The hole could be named in the internal structure.
> This is a bit of a gray area, but if you name this hole in uAPI and
> programs start referring to it you will never be able to reuse it.
> So you may as well not require it to be zeroed..
Hmm, yeah, suppose you're right. Doesn't the verifier prevent any part
of the memory from being unitialised anyway? I seem to recall having run
into verifier complaints when I didn't initialise struct on the stack...
-Toke
next prev parent reply other threads:[~2020-10-20 18:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 10:51 [PATCH bpf v2 0/3] bpf: Rework bpf_redirect_neigh() to allow supplying nexthop from caller Toke Høiland-Jørgensen
2020-10-20 10:51 ` [PATCH bpf v2 1/3] bpf_redirect_neigh: Support supplying the nexthop as a helper parameter Toke Høiland-Jørgensen
2020-10-20 15:08 ` Daniel Borkmann
2020-10-20 18:08 ` Toke Høiland-Jørgensen
2020-10-20 16:30 ` Jakub Kicinski
2020-10-20 18:08 ` Toke Høiland-Jørgensen [this message]
2020-10-20 19:01 ` Jakub Kicinski
2020-10-20 19:47 ` Daniel Borkmann
2020-10-20 18:12 ` David Ahern
2020-10-20 18:56 ` Jakub Kicinski
2020-10-20 16:34 ` Jakub Kicinski
2020-10-20 18:03 ` Toke Høiland-Jørgensen
2020-10-20 18:14 ` David Ahern
2020-10-20 18:50 ` Jakub Kicinski
2020-10-20 10:51 ` [PATCH bpf v2 2/3] bpf_fib_lookup: optionally skip neighbour lookup Toke Høiland-Jørgensen
2020-10-20 13:49 ` David Ahern
2020-10-20 15:04 ` Daniel Borkmann
2020-10-20 18:10 ` Toke Høiland-Jørgensen
2020-10-20 10:51 ` [PATCH bpf v2 3/3] selftests: Update test_tc_redirect.sh to use the modified bpf_redirect_neigh() Toke Høiland-Jørgensen
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