From mboxrd@z Thu Jan 1 00:00:00 1970 From: Auke Kok Subject: [PATCH 5/7] e1000e: fix flow control denial of service possibility Date: Thu, 21 Feb 2008 15:11:02 -0800 Message-ID: <20080221231102.5595.51852.stgit@localhost.localdomain> References: <20080221231041.5595.4933.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: e1000-devel@lists.sourceforge.net, netdev@vger.kernel.org To: jeff@garzik.org Return-path: In-Reply-To: <20080221231041.5595.4933.stgit@localhost.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: e1000-devel-bounces@lists.sourceforge.net Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org From: Jesse Brandeburg 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: Jesse Brandeburg Signed-off-by: Auke Kok --- drivers/net/e1000e/lib.c | 31 +++++-------------------------- 1 files changed, 5 insertions(+), 26 deletions(-) diff --git a/drivers/net/e1000e/lib.c b/drivers/net/e1000e/lib.c index 0860b5f..341d74e 100644 --- a/drivers/net/e1000e/lib.c +++ b/drivers/net/e1000e/lib.c @@ -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 if ((mac->original_fc == e1000_fc_none) || - (mac->original_fc == e1000_fc_tx_pause)) { + } else { + /* + * Per the IEEE spec, at this point flow control + * should be disabled. + */ 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- ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/