ipv6: Select fragment id during UFO segmentation if not set.

If the IPv6 fragment id has not been set and we perform
fragmentation due to UFO, select a new fragment id.
We now consider a fragment id of 0 as unset and if id selection
process returns 0 (after all the pertrubations), we set it to
0x80000000, thus giving us ample space not to create collisions
with the next packet we may have to fragment.

When doing UFO integrity checking, we also select the
fragment id if it has not be set yet.   This is stored into
the skb_shinfo() thus allowing UFO to function correclty.

This patch also removes duplicate fragment id generation code
and moves ipv6_select_ident() into the header as it may be
used during GSO.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 4292929392b0127479c49c5da3bb33f053f4428c..9bf85d34c024bc4bf0f2315ddaec630134fc90a7 100644 (file)
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -671,6 +671,9 @@ static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_add
        return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
 }
 
+u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst,
+                       struct in6_addr *src);
+void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt);
 void ipv6_proxy_select_ident(struct sk_buff *skb);
 
 int ip6_dst_hoplimit(struct dst_entry *dst);

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ce69a12ae48c29276871dacb30eebea086b291a3..d28f2a2efb32e4c06eadc45dc8167bb2cb766d32 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -537,20 +537,6 @@ static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
        skb_copy_secmark(to, from);
 }
 
-static void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
-{
-       static u32 ip6_idents_hashrnd __read_mostly;
-       u32 hash, id;
-
-       net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
-
-       hash = __ipv6_addr_jhash(&rt->rt6i_dst.addr, ip6_idents_hashrnd);
-       hash = __ipv6_addr_jhash(&rt->rt6i_src.addr, hash);
-
-       id = ip_idents_reserve(hash, 1);
-       fhdr->identification = htonl(id);
-}
-
 int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 {
        struct sk_buff *frag;

diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index 97f41a3e68d98b89d6b8f643780f8a883bd46f55..54520a0bd5e3b5feac3d4bc4221fac77ab990031 100644 (file)
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -9,6 +9,24 @@
 #include <net/addrconf.h>
 #include <net/secure_seq.h>
 
+u32 __ipv6_select_ident(u32 hashrnd, struct in6_addr *dst, struct in6_addr *src)
+{
+       u32 hash, id;
+
+       hash = __ipv6_addr_jhash(dst, hashrnd);
+       hash = __ipv6_addr_jhash(src, hash);
+
+       /* Treat id of 0 as unset and if we get 0 back from ip_idents_reserve,
+        * set the hight order instead thus minimizing possible future
+        * collisions.
+        */
+       id = ip_idents_reserve(hash, 1);
+       if (unlikely(!id))
+               id = 1 << 31;
+
+       return id;
+}
+
 /* This function exists only for tap drivers that must support broken
  * clients requesting UFO without specifying an IPv6 fragment ID.
  *
@@ -22,7 +40,7 @@ void ipv6_proxy_select_ident(struct sk_buff *skb)
        static u32 ip6_proxy_idents_hashrnd __read_mostly;
        struct in6_addr buf[2];
        struct in6_addr *addrs;
-       u32 hash, id;
+       u32 id;
 
        addrs = skb_header_pointer(skb,
                                   skb_network_offset(skb) +
@@ -34,14 +52,25 @@ void ipv6_proxy_select_ident(struct sk_buff *skb)
        net_get_random_once(&ip6_proxy_idents_hashrnd,
                            sizeof(ip6_proxy_idents_hashrnd));
 
-       hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
-       hash = __ipv6_addr_jhash(&addrs[0], hash);
-
-       id = ip_idents_reserve(hash, 1);
-       skb_shinfo(skb)->ip6_frag_id = htonl(id);
+       id = __ipv6_select_ident(ip6_proxy_idents_hashrnd,
+                                &addrs[1], &addrs[0]);
+       skb_shinfo(skb)->ip6_frag_id = id;
 }
 EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
 
+void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
+{
+       static u32 ip6_idents_hashrnd __read_mostly;
+       u32 id;
+
+       net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd));
+
+       id = __ipv6_select_ident(ip6_idents_hashrnd, &rt->rt6i_dst.addr,
+                                &rt->rt6i_src.addr);
+       fhdr->identification = htonl(id);
+}
+EXPORT_SYMBOL(ipv6_select_ident);
+
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 {
        u16 offset = sizeof(struct ipv6hdr);

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index b6aa8ed182579614d3738f107e839eb2e82e5371..a56276996b72b3f5d43121d6bf93422a58eefe62 100644 (file)
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -52,6 +52,10 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
 
                skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 
+               /* Set the IPv6 fragment id if not set yet */
+               if (!skb_shinfo(skb)->ip6_frag_id)
+                       ipv6_proxy_select_ident(skb);
+
                segs = NULL;
                goto out;
        }
@@ -108,7 +112,11 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
                fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
                fptr->nexthdr = nexthdr;
                fptr->reserved = 0;
-               fptr->identification = skb_shinfo(skb)->ip6_frag_id;
+               if (skb_shinfo(skb)->ip6_frag_id)
+                       fptr->identification = skb_shinfo(skb)->ip6_frag_id;
+               else
+                       ipv6_select_ident(fptr,
+                                         (struct rt6_info *)skb_dst(skb));
 
                /* Fragment the skb. ipv6 header and the remaining fields of the
                 * fragment header are updated in ipv6_gso_segment()