Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit de92d84e authored by Jesse Brandeburg's avatar Jesse Brandeburg Committed by Jeff Garzik
Browse files

e1000e: fix flow control denial of service possibility 



this patch avoids a denial of service from an evildoer sending a
continuous stream of flow control at our adapter that is plugged
into a non-flow control enabled switch.

Signed-off-by: default avatarJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: default avatarAuke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent 4a5694e6

drivers/net/e1000e/lib.c

+5 −26
Original line number Diff line number Diff line
@@ -1104,34 +1104,13 @@ s32 e1000e_config_fc_after_link_up(struct e1000_hw *hw) 
			 (mii_nway_lp_ability_reg & NWAY_LPAR_ASM_DIR)) {

			mac->fc = e1000_fc_rx_pause;

			hw_dbg(hw, "Flow Control = RX PAUSE frames only.\r\n");

		}

		/* Per the IEEE spec, at this point flow control should be

		 * disabled.  However, we want to consider that we could

		 * be connected to a legacy switch that doesn't advertise

		 * desired flow control, but can be forced on the link

		 * partner.  So if we advertised no flow control, that is

		 * what we will resolve to.  If we advertised some kind of

		 * receive capability (Rx Pause Only or Full Flow Control)

		 * and the link partner advertised none, we will configure

		 * ourselves to enable Rx Flow Control only.  We can do

		 * this safely for two reasons:  If the link partner really

		 * didn't want flow control enabled, and we enable Rx, no

		 * harm done since we won't be receiving any PAUSE frames

		 * anyway.  If the intent on the link partner was to have

		 * flow control enabled, then by us enabling RX only, we

		 * can at least receive pause frames and process them.

		 * This is a good idea because in most cases, since we are

		 * predominantly a server NIC, more times than not we will

		 * be asked to delay transmission of packets than asking

		 * our link partner to pause transmission of frames.

		} else {

			/*

			 * Per the IEEE spec, at this point flow control

			 * should be disabled.

			 */

		else if ((mac->original_fc == e1000_fc_none) ||

			 (mac->original_fc == e1000_fc_tx_pause)) {

			mac->fc = e1000_fc_none;

			hw_dbg(hw, "Flow Control = NONE.\r\n");

		} else {

			mac->fc = e1000_fc_rx_pause;

			hw_dbg(hw, "Flow Control = RX PAUSE frames only.\r\n");

		}



		/* Now we need to do one last check...  If we auto-