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Documentation: Update netlink_mmap.txt 

Update netlink_mmap.txt wrt. commit 4682a03586
("netlink: Always copy on mmap TX.").

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Richard Weinberger 2015-01-30 20:50:44 +01:00 committed by David S. Miller
parent 44ba582bea
commit e6b02be81b
1 changed files with 3 additions and 10 deletions
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13
Documentation/networking/netlink_mmap.txt
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@ -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
-------