xfrm: take net hdr len into account for esp payload size calculation
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 <bpoirier@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 @@
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_TRANSPORT:
+ case XFRM_MODE_BEET:
+ net_adj = sizeof(struct iphdr);
+ break;
case XFRM_MODE_TUNNEL:
+ net_adj = 0;
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);
- break;
+ 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 1e62b755..db1521f 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -413,19 +413,15 @@
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)
+ net_adj = sizeof(struct ipv6hdr);
+ else
+ net_adj = 0;
- if (x->props.mode != XFRM_MODE_TUNNEL) {
- u32 padsize = ((blksize - 1) & 7) + 1;
- mtu -= blksize - padsize;
- mtu += min_t(u32, blksize - padsize, rem);
- }
-
- 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,