netdev - Re: [PATCH RFC bpf-next 0/4] bpf: Add support for XDP programs in DEVMAPs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87v9kki523.fsf@toke.dk>
Date:   Mon, 25 May 2020 14:15:32 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     David Ahern <dsahern@...il.com>, David Ahern <dsahern@...nel.org>,
        netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, brouer@...hat.com,
        daniel@...earbox.net, john.fastabend@...il.com, ast@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com, andriin@...com
Subject: Re: [PATCH RFC bpf-next 0/4] bpf: Add support for XDP programs in DEVMAPs

David Ahern <dsahern@...il.com> writes:

> On 5/22/20 9:59 AM, Toke Høiland-Jørgensen wrote:
>> David Ahern <dsahern@...nel.org> writes:
>> 
>>> Implementation of Daniel's proposal for allowing DEVMAP entries to be
>>> a device index, program id pair. Daniel suggested an fd to specify the
>>> program, but that seems odd to me that you insert the value as an fd, but
>>> read it back as an id since the fd can be closed.
>> 
>> While I can be sympathetic to the argument that it seems odd, every
>> other API uses FD for insert and returns ID, so why make it different
>> here? Also, the choice has privilege implications, since the CAP_BPF
>> series explicitly makes going from ID->FD a more privileged operation
>> than just querying the ID.
>> 
>
> I do not like the model where the kernel changes the value the user
> pushed down.

Yet it's what we do in every other interface where a user needs to
supply a program, including in prog array maps. So let's not create a
new inconsistent interface here...

-Toke