netdev - Re: [PATCH bpf v2] net: bpf: don't leak time wait and request sockets

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: <20200110164328.aosamgjk5hfw7r7d@kafai-mbp.dhcp.thefacebook.com>
Date:   Fri, 10 Jan 2020 16:43:32 +0000
From:   Martin Lau <kafai@...com>
To:     Lorenz Bauer <lmb@...udflare.com>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Joe Stringer <joe@...valent.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-team@...udflare.com" <kernel-team@...udflare.com>
Subject: Re: [PATCH bpf v2] net: bpf: don't leak time wait and request sockets

On Fri, Jan 10, 2020 at 01:23:36PM +0000, Lorenz Bauer wrote:
> It's possible to leak time wait and request sockets via the following
> BPF pseudo code:
>  
>   sk = bpf_skc_lookup_tcp(...)
>   if (sk)
>     bpf_sk_release(sk)
> 
> If sk->sk_state is TCP_NEW_SYN_RECV or TCP_TIME_WAIT the refcount taken
> by bpf_skc_lookup_tcp is not undone by bpf_sk_release. This is because
> sk_flags is re-used for other data in both kinds of sockets. The check
> 
>   !sock_flag(sk, SOCK_RCU_FREE)
> 
> therefore returns a bogus result. Check that sk_flags is valid by calling
> sk_fullsock. Skip checking SOCK_RCU_FREE if we already know that sk is
> not a full socket.
Acked-by: Martin KaFai Lau <kafai@...com>