[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 <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 0c7d7b4..40d9a19 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -134,7 +134,7 @@
struct ipv6_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 ipv6_esp_hdr) - esp->conf.ivlen - alen;
@@ -236,13 +236,14 @@
static u32 esp6_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;
+ u32 padsize = ((blksize - 1) & 7) + 1;
+ mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
}
if (esp->conf.padlen)
mtu = ALIGN(mtu, esp->conf.padlen);