ipv6: fix incorrect ipsec fragment

Since commit ad0081e43a
"ipv6: Fragment locally generated tunnel-mode IPSec6 packets as needed"
the fragment of packets is incorrect.
because tunnel mode needs IPsec headers and trailer for all fragments,
while on transport mode it is sufficient to add the headers to the
first fragment and the trailer to the last.

so modify mtu and maxfraglen base on ipsec mode and if fragment is first
or last.

with my test,it work well(every fragment's size is the mtu)
and does not trigger slow fragment path.

Changes from v1:
	though optimization, mtu_prev and maxfraglen_prev can be delete.
	replace xfrm mode codes with dst_entry's new frag DST_XFRM_TUNNEL.
	add fuction ip6_append_data_mtu to make codes clearer.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/dst.h b/include/net/dst.h
index bed833d9796aed86bac5ca7d45ad53cde3447e52..8197eadca819633eb97f3919286a7e6b19bbcddd 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -60,6 +60,7 @@ struct dst_entry {
 #define DST_NOCOUNT            0x0020
 #define DST_NOPEER             0x0040
 #define DST_FAKE_RTABLE                0x0080
+#define DST_XFRM_TUNNEL                0x0100
 
        short                   error;
        short                   obsolete;

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index d99fdc699625ca34252a33e84e21d8179e0fad7a..17b8c67998bb80dc5e7052af210c7b64aa1471ee 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1187,6 +1187,29 @@ static inline struct ipv6_rt_hdr *ip6_rthdr_dup(struct ipv6_rt_hdr *src,
        return src ? kmemdup(src, (src->hdrlen + 1) * 8, gfp) : NULL;
 }
 
+static void ip6_append_data_mtu(int *mtu,
+                               int *maxfraglen,
+                               unsigned int fragheaderlen,
+                               struct sk_buff *skb,
+                               struct rt6_info *rt)
+{
+       if (!(rt->dst.flags & DST_XFRM_TUNNEL)) {
+               if (skb == NULL) {
+                       /* first fragment, reserve header_len */
+                       *mtu = *mtu - rt->dst.header_len;
+
+               } else {
+                       /*
+                        * this fragment is not first, the headers
+                        * space is regarded as data space.
+                        */
+                       *mtu = dst_mtu(rt->dst.path);
+               }
+               *maxfraglen = ((*mtu - fragheaderlen) & ~7)
+                             + fragheaderlen - sizeof(struct frag_hdr);
+       }
+}
+
 int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
        int offset, int len, int odd, struct sk_buff *skb),
        void *from, int length, int transhdrlen,
@@ -1196,7 +1219,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct inet_cork *cork;
-       struct sk_buff *skb;
+       struct sk_buff *skb, *skb_prev = NULL;
        unsigned int maxfraglen, fragheaderlen;
        int exthdrlen;
        int dst_exthdrlen;
@@ -1253,8 +1276,12 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                inet->cork.fl.u.ip6 = *fl6;
                np->cork.hop_limit = hlimit;
                np->cork.tclass = tclass;
-               mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
-                     rt->dst.dev->mtu : dst_mtu(&rt->dst);
+               if (rt->dst.flags & DST_XFRM_TUNNEL)
+                       mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
+                             rt->dst.dev->mtu : dst_mtu(&rt->dst);
+               else
+                       mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
+                             rt->dst.dev->mtu : dst_mtu(rt->dst.path);
                if (np->frag_size < mtu) {
                        if (np->frag_size)
                                mtu = np->frag_size;
@@ -1350,25 +1377,27 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                        unsigned int fraglen;
                        unsigned int fraggap;
                        unsigned int alloclen;
-                       struct sk_buff *skb_prev;
 alloc_new_skb:
-                       skb_prev = skb;
-
                        /* There's no room in the current skb */
-                       if (skb_prev)
-                               fraggap = skb_prev->len - maxfraglen;
+                       if (skb)
+                               fraggap = skb->len - maxfraglen;
                        else
                                fraggap = 0;
+                       /* update mtu and maxfraglen if necessary */
+                       if (skb == NULL || skb_prev == NULL)
+                               ip6_append_data_mtu(&mtu, &maxfraglen,
+                                                   fragheaderlen, skb, rt);
+
+                       skb_prev = skb;
 
                        /*
                         * If remaining data exceeds the mtu,
                         * we know we need more fragment(s).
                         */
                        datalen = length + fraggap;
-                       if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
-                               datalen = maxfraglen - fragheaderlen;
 
-                       fraglen = datalen + fragheaderlen;
+                       if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
+                               datalen = maxfraglen - fragheaderlen - rt->dst.trailer_len;
                        if ((flags & MSG_MORE) &&
                            !(rt->dst.dev->features&NETIF_F_SG))
                                alloclen = mtu;
@@ -1377,13 +1406,16 @@ alloc_new_skb:
 
                        alloclen += dst_exthdrlen;
 
-                       /*
-                        * The last fragment gets additional space at tail.
-                        * Note: we overallocate on fragments with MSG_MODE
-                        * because we have no idea if we're the last one.
-                        */
-                       if (datalen == length + fraggap)
-                               alloclen += rt->dst.trailer_len;
+                       if (datalen != length + fraggap) {
+                               /*
+                                * this is not the last fragment, the trailer
+                                * space is regarded as data space.
+                                */
+                               datalen += rt->dst.trailer_len;
+                       }
+
+                       alloclen += rt->dst.trailer_len;
+                       fraglen = datalen + fragheaderlen;
 
                        /*
                         * We just reserve space for fragment header.

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index c53e8f42aa7506b897464a3716e282b0c837a549..ccfbd328a69d7948736157555bfa857236875156 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1921,6 +1921,9 @@ no_transform:
        }
 ok:
        xfrm_pols_put(pols, drop_pols);
+       if (dst && dst->xfrm &&
+           dst->xfrm->props.mode == XFRM_MODE_TUNNEL)
+               dst->flags |= DST_XFRM_TUNNEL;
        return dst;
 
 nopol: