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xfrm: take net hdr len into account for esp payload size calculation

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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>
This commit is contained in:
Benjamin Poirier 2012-05-24 11:32:38 +00:00 committed by David S. Miller
parent f0d1b3c2bc
commit 91657eafb6
2 changed files with 16 additions and 26 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

24
net/ipv4/esp4.c
View file

@ -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_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)

18
net/ipv6/esp6.c
View file

@ -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)
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,