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

[~andy/linux] / net / ipv4 / esp4.c

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 89a47b35905dcc6e1c3bb94b0db7c6a32a61e8fc..cb982a61536fade811908a18e6119f513914741e 100644 (file)
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -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_TUNNEL:
-               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);
+               net_adj = sizeof(struct iphdr);
                break;
+       case XFRM_MODE_TUNNEL:
+               net_adj = 0;
+               break;
+       default:
+               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)