Merge branch 'linux-linaro-lsk' into linux-linaro-lsk-android

[firefly-linux-kernel-4.4.55.git] / net / ipv4 / route.c

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index bea0e1f2df0e5f2d9e4e0edbbc3ec129cee69e05..43ef33d5b9149a3b79dd1f6c98e6c133aee9bd24 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -89,6 +89,7 @@
 #include <linux/rcupdate.h>
 #include <linux/times.h>
 #include <linux/slab.h>
+#include <linux/jhash.h>
 #include <net/dst.h>
 #include <net/net_namespace.h>
 #include <net/protocol.h>
@@ -464,39 +465,53 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
        return neigh_create(&arp_tbl, pkey, dev);
 }
 
-/*
- * Peer allocation may fail only in serious out-of-memory conditions.  However
- * we still can generate some output.
- * Random ID selection looks a bit dangerous because we have no chances to
- * select ID being unique in a reasonable period of time.
- * But broken packet identifier may be better than no packet at all.
+#define IP_IDENTS_SZ 2048u
+struct ip_ident_bucket {
+       atomic_t        id;
+       u32             stamp32;
+};
+
+static struct ip_ident_bucket *ip_idents __read_mostly;
+
+/* In order to protect privacy, we add a perturbation to identifiers
+ * if one generator is seldom used. This makes hard for an attacker
+ * to infer how many packets were sent between two points in time.
  */
-static void ip_select_fb_ident(struct iphdr *iph)
+u32 ip_idents_reserve(u32 hash, int segs)
 {
-       static DEFINE_SPINLOCK(ip_fb_id_lock);
-       static u32 ip_fallback_id;
-       u32 salt;
+       struct ip_ident_bucket *bucket = ip_idents + hash % IP_IDENTS_SZ;
+       u32 old = ACCESS_ONCE(bucket->stamp32);
+       u32 now = (u32)jiffies;
+       u32 delta = 0;
+
+       if (old != now && cmpxchg(&bucket->stamp32, old, now) == old) {
+               u64 x = prandom_u32();
+
+               x *= (now - old);
+               delta = (u32)(x >> 32);
+       }
 
-       spin_lock_bh(&ip_fb_id_lock);
-       salt = secure_ip_id((__force __be32)ip_fallback_id ^ iph->daddr);
-       iph->id = htons(salt & 0xFFFF);
-       ip_fallback_id = salt;
-       spin_unlock_bh(&ip_fb_id_lock);
+       return atomic_add_return(segs + delta, &bucket->id) - segs;
 }
+EXPORT_SYMBOL(ip_idents_reserve);
 
-void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more)
+void __ip_select_ident(struct iphdr *iph, int segs)
 {
-       struct net *net = dev_net(dst->dev);
-       struct inet_peer *peer;
+       static u32 ip_idents_hashrnd __read_mostly;
+       static bool hashrnd_initialized = false;
+       u32 hash, id;
 
-       peer = inet_getpeer_v4(net->ipv4.peers, iph->daddr, 1);
-       if (peer) {
-               iph->id = htons(inet_getid(peer, more));
-               inet_putpeer(peer);
-               return;
+       if (unlikely(!hashrnd_initialized)) {
+               hashrnd_initialized = true;
+               get_random_bytes(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
        }
 
-       ip_select_fb_ident(iph);
+       hash = jhash_3words((__force u32)iph->daddr,
+                           (__force u32)iph->saddr,
+                           iph->protocol,
+                           ip_idents_hashrnd);
+       id = ip_idents_reserve(hash, segs);
+       iph->id = htons(id);
 }
 EXPORT_SYMBOL(__ip_select_ident);
 
@@ -992,20 +1007,21 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
        const struct iphdr *iph = (const struct iphdr *) skb->data;
        struct flowi4 fl4;
        struct rtable *rt;
-       struct dst_entry *dst;
+       struct dst_entry *odst = NULL;
        bool new = false;
 
        bh_lock_sock(sk);
-       rt = (struct rtable *) __sk_dst_get(sk);
+       odst = sk_dst_get(sk);
 
-       if (sock_owned_by_user(sk) || !rt) {
+       if (sock_owned_by_user(sk) || !odst) {
                __ipv4_sk_update_pmtu(skb, sk, mtu);
                goto out;
        }
 
        __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
 
-       if (!__sk_dst_check(sk, 0)) {
+       rt = (struct rtable *)odst;
+       if (odst->obsolete && odst->ops->check(odst, 0) == NULL) {
                rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
                if (IS_ERR(rt))
                        goto out;
@@ -1015,8 +1031,7 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
 
        __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
 
-       dst = dst_check(&rt->dst, 0);
-       if (!dst) {
+       if (!dst_check(&rt->dst, 0)) {
                if (new)
                        dst_release(&rt->dst);
 
@@ -1028,10 +1043,11 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
        }
 
        if (new)
-               __sk_dst_set(sk, &rt->dst);
+               sk_dst_set(sk, &rt->dst);
 
 out:
        bh_unlock_sock(sk);
+       dst_release(odst);
 }
 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
 
@@ -2662,6 +2678,12 @@ int __init ip_rt_init(void)
 {
        int rc = 0;
 
+       ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
+       if (!ip_idents)
+               panic("IP: failed to allocate ip_idents\n");
+
+       prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
+
 #ifdef CONFIG_IP_ROUTE_CLASSID
        ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
        if (!ip_rt_acct)