From d4875b049b2e6401a6e1fae90b7f09e20a636fcf Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 10 Oct 2005 21:11:34 -0700 Subject: [IPSEC] Fix block size/MTU bugs in ESP This patch fixes the following bugs in ESP: * Fix transport mode MTU overestimate. This means that the inner MTU is smaller than it needs be. Worse yet, given an input MTU which is a multiple of 4 it will always produce an estimate which is not a multiple of 4. For example, given a standard ESP/3DES/MD5 transform and an MTU of 1500, the resulting MTU for transport mode is 1462 when it should be 1464. The reason for this is because IP header lengths are always a multiple of 4 for IPv4 and 8 for IPv6. * Ensure that the block size is at least 4. This is required by RFC2406 and corresponds to what the esp_output function does. At the moment this only affects crypto_null as its block size is 1. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- net/ipv4/esp4.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/ipv4/esp4.c') diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index e911c6dd8296..1b18ce66e7b7 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -144,7 +144,7 @@ static int esp_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struc struct ip_esp_hdr *esph; struct esp_data *esp = x->data; struct sk_buff *trailer; - int blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); + int blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); int alen = esp->auth.icv_trunc_len; int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen; int nfrags; @@ -305,13 +305,13 @@ static int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, static u32 esp4_get_max_size(struct xfrm_state *x, int mtu) { struct esp_data *esp = x->data; - u32 blksize = crypto_tfm_alg_blocksize(esp->conf.tfm); + u32 blksize = ALIGN(crypto_tfm_alg_blocksize(esp->conf.tfm), 4); if (x->props.mode) { mtu = ALIGN(mtu + 2, blksize); } else { /* The worst case. */ - mtu += 2 + blksize; + mtu = ALIGN(mtu + 2, 4) + blksize - 4; } if (esp->conf.padlen) mtu = ALIGN(mtu, esp->conf.padlen); -- cgit v1.2.1