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  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]
Date:   Mon, 21 Sep 2020 11:42:13 +0100
From:   Lorenz Bauer <>
To:     Maciej ┼╗enczykowski <>
Cc:     Jesper Dangaard Brouer <>,
        Daniel Borkmann <>,
        Alexei Starovoitov <>,
        BPF-dev-list <>,
        "" <>,
        Lorenzo Bianconi <>,
        John Fastabend <>,
        Jakub Kicinski <>,
        Shaun Crampton <>,
        David Miller <>,
        Marek Majkowski <>
Subject: Re: BPF redirect API design issue for BPF-prog MTU feedback?

On Thu, 17 Sep 2020 at 13:55, Maciej ┼╗enczykowski <> wrote:
> (b) another complexity with bpf_redirect() is you can call it, it can succeed,
> but then you can not return TC_ACT_REDIRECT from the bpf program,
> which effectively makes the earlier *successful* bpf_redirect() call
> an utter no-op.
> (bpf_redirect() just determines what a future return TC_ACT_REDIRECT will do)
> so if you bpf_redirect to interface with larger mtu, then increase packet size,
> then return TC_ACT_OK, then you potentially end up with excessively large
> packet egressing through original interface (with small mtu).

Yeah, this isn't nice. What is the use case for allowing this in the
first place?

For sk_lookup programs, we have a similar situation, except that we
"redirect" to a socket. Here the redirect happens if the helper call
is successful and the program returns SK_PASS. Maybe that is a
feasible approach if we introduce new helpers.

Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

Powered by blists - more mailing lists