Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965603Ab2EXVdi (ORCPT ); Thu, 24 May 2012 17:33:38 -0400 Received: from mail-gg0-f174.google.com ([209.85.161.174]:52714 "EHLO mail-gg0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933393Ab2EXVdf (ORCPT ); Thu, 24 May 2012 17:33:35 -0400 From: Benjamin Poirier To: netdev@vger.kernel.org Cc: "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , linux-kernel@vger.kernel.org, Steffen Klassert , Diego Beltrami Subject: [PATCH v4] xfrm: take net hdr len into account for esp payload size calculation Date: Thu, 24 May 2012 17:32:38 -0400 Message-Id: <1337895158-23521-1-git-send-email-bpoirier@suse.de> X-Mailer: git-send-email 1.7.7 In-Reply-To: <20120517.200509.2290282427866555176.davem@davemloft.net> References: <20120517.200509.2290282427866555176.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3760 Lines: 128 Corrects the function that determines the esp payload size. The calculations done in esp{4,6}_get_mtu() lead to overlength frames in transport mode for certain mtu values and suboptimal frames for others. According to what is done, mainly in esp{,6}_output() and tcp_mtu_to_mss(), net_header_len must be taken into account before doing the alignment calculation. Signed-off-by: Benjamin Poirier --- Changes since v3: * also fix ipv6 Changes since v2: * rename l3_adj to net_adj * fix indentation Changes since v1: * introduce l3_adj to preserve the same returned value as before for tunnel mode For example: * on ipv4 with md5 AH and 3des ESP (transport mode): mtu = 1499 leads to FRAGFAILS mtu = 1500 the addition of padding in the esp header could be avoided * on ipv6 with md5 AH and twofish-sha1 ESP (transport mode): mtu = 1491 leads to Ip6FragFails mtu = 1499 padding can be avoided For details on how the formula is established, see https://lkml.org/lkml/2012/5/10/597 Tested with * transport mode E * transport mode EA * transport mode E + ah * tunnel mode E Not tested with BEET, but it should be the same as transport mode draft-nikander-esp-beet-mode-03.txt Section 5.2: "The wire packet format is identical to the ESP transport mode" --- net/ipv4/esp4.c | 24 +++++++++--------------- net/ipv6/esp6.c | 18 +++++++----------- 2 files changed, 16 insertions(+), 26 deletions(-) diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index 89a47b3..cb982a6 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -459,28 +459,22 @@ static u32 esp4_get_mtu(struct xfrm_state *x, int mtu) struct esp_data *esp = x->data; u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); u32 align = max_t(u32, blksize, esp->padlen); - u32 rem; - - mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); - rem = mtu & (align - 1); - mtu &= ~(align - 1); + unsigned int net_adj; switch (x->props.mode) { - case XFRM_MODE_TUNNEL: - break; - default: case XFRM_MODE_TRANSPORT: - /* The worst case */ - mtu -= blksize - 4; - mtu += min_t(u32, blksize - 4, rem); - break; case XFRM_MODE_BEET: - /* The worst case. */ - mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem); + net_adj = sizeof(struct iphdr); break; + case XFRM_MODE_TUNNEL: + net_adj = 0; + break; + default: + BUG(); } - return mtu - 2; + return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - + net_adj) & ~(align - 1)) + (net_adj - 2); } static void esp4_err(struct sk_buff *skb, u32 info) diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c index 1e62b75..db1521f 100644 --- a/net/ipv6/esp6.c +++ b/net/ipv6/esp6.c @@ -413,19 +413,15 @@ static u32 esp6_get_mtu(struct xfrm_state *x, int mtu) struct esp_data *esp = x->data; u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4); u32 align = max_t(u32, blksize, esp->padlen); - u32 rem; + unsigned int net_adj; - mtu -= x->props.header_len + crypto_aead_authsize(esp->aead); - rem = mtu & (align - 1); - mtu &= ~(align - 1); - - if (x->props.mode != XFRM_MODE_TUNNEL) { - u32 padsize = ((blksize - 1) & 7) + 1; - mtu -= blksize - padsize; - mtu += min_t(u32, blksize - padsize, rem); - } + if (x->props.mode != XFRM_MODE_TUNNEL) + net_adj = sizeof(struct ipv6hdr); + else + net_adj = 0; - return mtu - 2; + return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) - + net_adj) & ~(align - 1)) + (net_adj - 2); } static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/