From: Benjamin Poirier <redacted>
Date: Wed, 16 May 2012 15:35:25 -0400

Corrects the function that determines the esp payload size.
The calculations done in esp4_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_output(), net_header_len aka
sizeof(struct iphdr) must be taken into account before doing the alignment
calculation.

Signed-off-by: Benjamin Poirier <redacted>

This looks great.

Could you please fix net/ipv6/esp6.c too, it seems to have the same
exact bug.

Once you respin this patch with both ipv4 and ipv6 fixed, I'll apply
it.

Thank you.