From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Weinberger Subject: [PATCH] Documentation: Update netlink_mmap.txt Date: Fri, 30 Jan 2015 20:50:44 +0100 Message-ID: <1422647444-4004-1-git-send-email-richard@nod.at> Cc: corbet@lwn.net, shemming@brocade.com, linux-doc@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Richard Weinberger To: davem@davemloft.net Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Update netlink_mmap.txt wrt. commit 4682a0358639b29cf ("netlink: Always copy on mmap TX."). Signed-off-by: Richard Weinberger --- Documentation/networking/netlink_mmap.txt | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/Documentation/networking/netlink_mmap.txt b/Documentation/networking/netlink_mmap.txt index c6af4ba..30a95fd 100644 --- a/Documentation/networking/netlink_mmap.txt +++ b/Documentation/networking/netlink_mmap.txt @@ -199,16 +199,9 @@ frame header. TX limitations -------------- -Kernel processing usually involves validation of the message received by -user-space, then processing its contents. The kernel must assure that -userspace is not able to modify the message contents after they have been -validated. In order to do so, the message is copied from the ring frame -to an allocated buffer if either of these conditions is false: - -- only a single mapping of the ring exists -- the file descriptor is not shared between processes - -This means that for threaded programs, the kernel will fall back to copying. +As of Jan 2015 the message is always copied from the ring frame to an +allocated buffer due to unresolved security concerns. +See commit 4682a0358639b29cf ("netlink: Always copy on mmap TX."). Example ------- -- 2.2.2