Neil, I couple of comments below, I was just looking at the implementation of this for e1000e.
On Mon, 28 Dec 2009, Neil Horman wrote: > Hey all- > A security discussion was recently given: > http://events.ccc.de/congress/2009/Fahrplan//events/3596.en.html > And a patch that I submitted awhile back was brought up. Apparently some of > their testing revealed that they were able to force a buffer fragment in e1000 > in which the trailing fragment was greater than 4 bytes. As a result the > fragment check I introduced failed to detect the fragement and a partial > invalid > frame was passed up into the network stack. I've written this patch to > correct > it. I'm in the process of testing it now, but it makes good logical sense to > me. Effectively it maintains a per-adapter state variable which detects a > non-EOP frame, and discards it and subsequent non-EOP frames leading up to > _and_ > _including_ the next positive-EOP frame (as it is by definition the last > fragment). This should prevent any and all partial frames from entering the > network stack from e1000 > > Regards > Neil > > > e1000.h | 3 ++- > e1000_main.c | 14 ++++++++++++-- > 2 files changed, 14 insertions(+), 3 deletions(-) > > > diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h > index 2a567df..3d421ab 100644 > --- a/drivers/net/e1000/e1000.h > +++ b/drivers/net/e1000/e1000.h > @@ -331,7 +331,8 @@ struct e1000_adapter { > enum e1000_state_t { > __E1000_TESTING, > __E1000_RESETTING, > - __E1000_DOWN > + __E1000_DOWN, > + __E1000_DISCARDING > }; > > extern char e1000_driver_name[]; > diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c > index 7e855f9..0731779 100644 > --- a/drivers/net/e1000/e1000_main.c > +++ b/drivers/net/e1000/e1000_main.c > @@ -3850,16 +3850,26 @@ static bool e1000_clean_rx_irq(struct e1000_adapter > *adapter, > > length = le16_to_cpu(rx_desc->length); > /* !EOP means multiple descriptors were used to store a single > - * packet, also make sure the frame isn't just CRC only */ > - if (unlikely(!(status & E1000_RXD_STAT_EOP) || (length <= 4))) { > + * packet, if thats the case we need to toss it. In fact, we > + * to toss every packet with the EOP bit clear and the next > + * frame that _does_ have the EOP bit set, as it is by > + * definition only a frame fragment > + */ > + if (unlikely(!(status & E1000_RXD_STAT_EOP))) > + set_bit(__E1000_DISCARDING, &adapter->flags); test_bit and set_bit and clear_bit are atomic operations, isn't that quite a bit of overhead for something that is already being done in a guaranteed single context? > + > + if (test_bit(__E1000_DISCARDING, &adapter->flags)) { > /* All receives must fit into a single buffer */ > E1000_DBG("%s: Receive packet consumed multiple" > " buffers\n", netdev->name); > /* recycle */ > buffer_info->skb = skb; > + if (status & E1000_RXD_STAT_EOP) > + clear_bit(__E1000_DISCARDING, &adapter->flags); couldn't these simply be read/modify/write assignments (aka |=) That would significantly avoid the extra cycles needed to implement three atomic ops. ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel
