netdev - Re: [PATCH bpf-next v2] net: Don't call XDP_SETUP

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20190814150123.6b5124e8@cakuba.netronome.com>
Date:   Wed, 14 Aug 2019 15:01:23 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Maxim Mikityanskiy <maximmi@...lanox.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>
Subject: Re: [PATCH bpf-next v2] net: Don't call XDP_SETUP_PROG when nothing
 is changed

On Wed, 14 Aug 2019 14:34:06 +0000, Maxim Mikityanskiy wrote:
> Don't uninstall an XDP program when none is installed, and don't install
> an XDP program that has the same ID as the one already installed.
> 
> dev_change_xdp_fd doesn't perform any checks in case it uninstalls an
> XDP program. It means that the driver's ndo_bpf can be called with
> XDP_SETUP_PROG asking to set it to NULL even if it's already NULL. This
> case happens if the user runs `ip link set eth0 xdp off` when there is
> no XDP program attached.
> 
> The symmetrical case is possible when the user tries to set the program
> that is already set.
> 
> The drivers typically perform some heavy operations on XDP_SETUP_PROG,
> so they all have to handle these cases internally to return early if
> they happen. This patch puts this check into the kernel code, so that
> all drivers will benefit from it.
> 
> Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>

Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>