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]
Date:   Tue, 28 Feb 2017 11:46:23 -0800
From:   Andy Lutomirski <>
To:     Michael Kerrisk <>
Cc:     Willem de Bruijn <>,
        netdev <>,
        Willem de Bruijn <>,
        Linux API <>
Subject: Re: [PATCH RFC v2 00/12] socket sendmsg MSG_ZEROCOPY

On Mon, Feb 27, 2017 at 10:57 AM, Michael Kerrisk
<> wrote:
> [CC +=]
> Hi Willem

>> On a send call with MSG_ZEROCOPY, the kernel pins the user pages and
>> creates skbuff fragments directly from these pages. On tx completion,
>> it notifies the socket owner that it is safe to modify memory by
>> queuing a completion notification onto the socket error queue.

What happens if the user writes to the pages while it's not safe?

How about if you're writing to an interface or a route that has crypto
involved and a malicious user can make the data change in the middle
of a crypto operation, thus perhaps leaking the entire key?  (I
wouldn't be at all surprised if a lot of provably secure AEAD
constructions are entirely compromised if an attacker can get the
ciphertext and tag computed from a message that changed during the

I can see this working if you have a special type of skb that
indicates that the data might be concurrently written and have all the
normal skb APIs (including, especially, anything that clones it) make
a copy first.


Powered by blists - more mailing lists