[XFRM]: beet: fix worst case header_len calculation

esp_init_state doesn't account for the beet pseudo header in the header_len
calculation, which may result in undersized skbs hitting xfrm4_beet_output,
causing unnecessary reallocations in ip_finish_output2.

The skbs should still always have enough room to avoid causing
skb_under_panic in skb_push since we have at least 16 bytes available
from LL_RESERVED_SPACE in xfrm_state_check_space.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index a315d5d227644ef2e905d98cf38fcfb7ac126ca5..47c95e8ef0456483937d810d3647f263e0a42bf6 100644 (file)
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -294,7 +294,6 @@ static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
                break;
        case XFRM_MODE_BEET:
                /* The worst case. */
-               mtu -= IPV4_BEET_PHMAXLEN;
                mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
                break;
        }
@@ -409,6 +408,8 @@ static int esp_init_state(struct xfrm_state *x)
        x->props.header_len = sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
        if (x->props.mode == XFRM_MODE_TUNNEL)
                x->props.header_len += sizeof(struct iphdr);
+       else if (x->props.mode == XFRM_MODE_BEET)
+               x->props.header_len += IPV4_BEET_PHMAXLEN;
        if (x->encap) {
                struct xfrm_encap_tmpl *encap = x->encap;
 

diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
index 0f7c3e30e4e6b2072bcb4e51d8ad3279695a76a2..a73e710740c22396c4bff28337c53ea6b8624565 100644 (file)
--- a/net/ipv4/xfrm4_mode_beet.c
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -40,7 +40,7 @@ static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
        if (unlikely(optlen))
                hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
 
-       skb_push(skb, x->props.header_len + hdrlen);
+       skb_push(skb, x->props.header_len - IPV4_BEET_PHMAXLEN + hdrlen);
        skb_reset_network_header(skb);
        top_iph = ip_hdr(skb);
        skb->transport_header += sizeof(*iph) - hdrlen;