netdev - Re: [PATCH bpf] bpf, sockmap: fix sock_hash

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Message-ID: <CAPhsuW44kx=zkSiz-dJiexJgOU8xmPLwS1gSPDgTF0fZZciLEQ@mail.gmail.com>
Date:   Tue, 21 Aug 2018 17:12:30 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf] bpf, sockmap: fix sock_hash_alloc and reject
 zero-sized keys

On Tue, Aug 21, 2018 at 3:02 PM, Daniel Borkmann <daniel@...earbox.net> wrote:
> Currently, it is possible to create a sock hash map with key size
> of 0 and have the kernel return a fd back to user space. This is
> invalid for hash maps (and kernel also hasn't been tested for zero
> key size support in general at this point). Thus, reject such
> configuration.
>
> Fixes: 81110384441a ("bpf: sockmap, add hash map support")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Acked-by: John Fastabend <john.fastabend@...il.com>

Acked-by: Song Liu <songliubraving@...com>

> ---
>  kernel/bpf/sockmap.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
> index 98e621a..60ceb0e 100644
> --- a/kernel/bpf/sockmap.c
> +++ b/kernel/bpf/sockmap.c
> @@ -2140,7 +2140,9 @@ static struct bpf_map *sock_hash_alloc(union bpf_attr *attr)
>                 return ERR_PTR(-EPERM);
>
>         /* check sanity of attributes */
> -       if (attr->max_entries == 0 || attr->value_size != 4 ||
> +       if (attr->max_entries == 0 ||
> +           attr->key_size == 0 ||
> +           attr->value_size != 4 ||
>             attr->map_flags & ~SOCK_CREATE_FLAG_MASK)
>                 return ERR_PTR(-EINVAL);
>
> --
> 2.9.5
>