[net-2.6 PATCH 1/2] e1000: enhance frame fragment detection

[net-2.6 PATCH 1/2] e1000: enhance frame fragment detection

[Jeff Kirsher]

From: Jesse Brandeburg <jesse.brandeburg@intel.com>

Originally From: Neil Horman <nhorman@tuxdriver.com>
Modified by: Jesse Brandeburg <jesse.brandeburg@intel.com>

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.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/e1000/e1000.h      |    2 ++
 drivers/net/e1000/e1000_main.c |   13 +++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
index 2a567df..e8932db 100644
--- a/drivers/net/e1000/e1000.h
+++ b/drivers/net/e1000/e1000.h
@@ -326,6 +326,8 @@ struct e1000_adapter {
 	/* for ioport free */
 	int bars;
 	int need_ioport;
+
+	bool discarding;
 };
 
 enum e1000_state_t {
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 7e855f9..9bc9fcd 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3850,13 +3850,22 @@ 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)))
+			adapter->discarding = true;
+
+		if (adapter->discarding) {
 			/* 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)
+				adapter->discarding = false;
 			goto next_desc;
 		}
 

[net-2.6 PATCH 2/2] e1000e: enhance frame fragment detection

[Jeff Kirsher]

From: Jesse Brandeburg <jesse.brandeburg@intel.com>

Originally patched by Neil Horman <nhorman@tuxdriver.com>

e1000e could with a jumbo frame enabled interface, and packet split disabled,
receive a packet that would overflow a single rx buffer.  While in practice
very hard to craft a packet that could abuse this, it is possible.

this is related to CVE-2009-4538

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/e1000e/e1000.h  |    1 +
 drivers/net/e1000e/netdev.c |   25 +++++++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
index d6ee28f..d236efa 100644
--- a/drivers/net/e1000e/e1000.h
+++ b/drivers/net/e1000e/e1000.h
@@ -421,6 +421,7 @@ struct e1000_info {
 /* CRC Stripping defines */
 #define FLAG2_CRC_STRIPPING               (1 << 0)
 #define FLAG2_HAS_PHY_WAKEUP              (1 << 1)
+#define FLAG2_IS_DISCARDING               (1 << 2)
 
 #define E1000_RX_DESC_PS(R, i)	    \
 	(&(((union e1000_rx_desc_packet_split *)((R).desc))[i]))
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index c45965a..da5838e 100644
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -450,13 +450,23 @@ 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 (!(status & E1000_RXD_STAT_EOP) || (length <= 4)) {
+		/*
+		 * !EOP means multiple descriptors were used to store a single
+		 * packet, if that's the case we need to toss it.  In fact, we
+		 * need 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)))
+			adapter->flags2 |= FLAG2_IS_DISCARDING;
+
+		if (adapter->flags2 & FLAG2_IS_DISCARDING) {
 			/* All receives must fit into a single buffer */
 			e_dbg("Receive packet consumed multiple buffers\n");
 			/* recycle */
 			buffer_info->skb = skb;
+			if (status & E1000_RXD_STAT_EOP)
+				adapter->flags2 &= ~FLAG2_IS_DISCARDING;
 			goto next_desc;
 		}
 
@@ -745,10 +755,16 @@ static bool e1000_clean_rx_irq_ps(struct e1000_adapter *adapter,
 				 PCI_DMA_FROMDEVICE);
 		buffer_info->dma = 0;
 
-		if (!(staterr & E1000_RXD_STAT_EOP)) {
+		/* see !EOP comment in other rx routine */
+		if (!(staterr & E1000_RXD_STAT_EOP))
+			adapter->flags2 |= FLAG2_IS_DISCARDING;
+
+		if (adapter->flags2 & FLAG2_IS_DISCARDING) {
 			e_dbg("Packet Split buffers didn't pick up the full "
 			      "packet\n");
 			dev_kfree_skb_irq(skb);
+			if (staterr & E1000_RXD_STAT_EOP)
+				adapter->flags2 &= ~FLAG2_IS_DISCARDING;
 			goto next_desc;
 		}
 
@@ -1118,6 +1134,7 @@ static void e1000_clean_rx_ring(struct e1000_adapter *adapter)
 
 	rx_ring->next_to_clean = 0;
 	rx_ring->next_to_use = 0;
+	adapter->flags2 &= ~FLAG2_IS_DISCARDING;
 
 	writel(0, adapter->hw.hw_addr + rx_ring->head);
 	writel(0, adapter->hw.hw_addr + rx_ring->tail);

Re: [net-2.6 PATCH 2/2] e1000e: enhance frame fragment detection

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Tue, 19 Jan 2010 16:15:59 -0800

> From: Jesse Brandeburg <jesse.brandeburg@intel.com>
> 
> Originally patched by Neil Horman <nhorman@tuxdriver.com>
> 
> e1000e could with a jumbo frame enabled interface, and packet split disabled,
> receive a packet that would overflow a single rx buffer.  While in practice
> very hard to craft a packet that could abuse this, it is possible.
> 
> this is related to CVE-2009-4538
> 
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> CC: Neil Horman <nhorman@tuxdriver.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied.

Re: [net-2.6 PATCH 1/2] e1000: enhance frame fragment detection

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Tue, 19 Jan 2010 16:15:38 -0800

> From: Jesse Brandeburg <jesse.brandeburg@intel.com>
> 
> Originally From: Neil Horman <nhorman@tuxdriver.com>
> Modified by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> 
> 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.
> 
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
> Acked-by: Neil Horman <nhorman@tuxdriver.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied.