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authorEric Dumazet <edumazet@google.com>2014-06-02 05:26:03 -0700
committerDavid S. Miller <davem@davemloft.net>2014-06-02 11:00:41 -0700
commit73f156a6e8c1074ac6327e0abd1169e95eb66463 (patch)
tree2c8b222f21784e738c397ba95dee70a8f256ea64 /net/ipv4
parente067ee336a9d3f038ffa9699c59f2abec3376bf7 (diff)
inetpeer: get rid of ip_id_count
Ideally, we would need to generate IP ID using a per destination IP generator. linux kernels used inet_peer cache for this purpose, but this had a huge cost on servers disabling MTU discovery. 1) each inet_peer struct consumes 192 bytes 2) inetpeer cache uses a binary tree of inet_peer structs, with a nominal size of ~66000 elements under load. 3) lookups in this tree are hitting a lot of cache lines, as tree depth is about 20. 4) If server deals with many tcp flows, we have a high probability of not finding the inet_peer, allocating a fresh one, inserting it in the tree with same initial ip_id_count, (cf secure_ip_id()) 5) We garbage collect inet_peer aggressively. IP ID generation do not have to be 'perfect' Goal is trying to avoid duplicates in a short period of time, so that reassembly units have a chance to complete reassembly of fragments belonging to one message before receiving other fragments with a recycled ID. We simply use an array of generators, and a Jenkin hash using the dst IP as a key. ipv6_select_ident() is put back into net/ipv6/ip6_output.c where it belongs (it is only used from this file) secure_ip_id() and secure_ipv6_id() no longer are needed. Rename ip_select_ident_more() to ip_select_ident_segs() to avoid unnecessary decrement/increment of the number of segments. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/igmp.c4
-rw-r--r--net/ipv4/inetpeer.c18
-rw-r--r--net/ipv4/ip_output.c7
-rw-r--r--net/ipv4/ip_tunnel_core.c2
-rw-r--r--net/ipv4/ipmr.c2
-rw-r--r--net/ipv4/raw.c2
-rw-r--r--net/ipv4/route.c45
-rw-r--r--net/ipv4/xfrm4_mode_tunnel.c2
8 files changed, 25 insertions, 57 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 17d34e3c2ac3..6748d420f714 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -369,7 +369,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size)
pip->saddr = fl4.saddr;
pip->protocol = IPPROTO_IGMP;
pip->tot_len = 0; /* filled in later */
- ip_select_ident(skb, &rt->dst, NULL);
+ ip_select_ident(skb, NULL);
((u8 *)&pip[1])[0] = IPOPT_RA;
((u8 *)&pip[1])[1] = 4;
((u8 *)&pip[1])[2] = 0;
@@ -714,7 +714,7 @@ static int igmp_send_report(struct in_device *in_dev, struct ip_mc_list *pmc,
iph->daddr = dst;
iph->saddr = fl4.saddr;
iph->protocol = IPPROTO_IGMP;
- ip_select_ident(skb, &rt->dst, NULL);
+ ip_select_ident(skb, NULL);
((u8 *)&iph[1])[0] = IPOPT_RA;
((u8 *)&iph[1])[1] = 4;
((u8 *)&iph[1])[2] = 0;
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index c98cf141f4ed..4ced1b9a97f0 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -26,20 +26,7 @@
* Theory of operations.
* We keep one entry for each peer IP address. The nodes contains long-living
* information about the peer which doesn't depend on routes.
- * At this moment this information consists only of ID field for the next
- * outgoing IP packet. This field is incremented with each packet as encoded
- * in inet_getid() function (include/net/inetpeer.h).
- * At the moment of writing this notes identifier of IP packets is generated
- * to be unpredictable using this code only for packets subjected
- * (actually or potentially) to defragmentation. I.e. DF packets less than
- * PMTU in size when local fragmentation is disabled use a constant ID and do
- * not use this code (see ip_select_ident() in include/net/ip.h).
*
- * Route cache entries hold references to our nodes.
- * New cache entries get references via lookup by destination IP address in
- * the avl tree. The reference is grabbed only when it's needed i.e. only
- * when we try to output IP packet which needs an unpredictable ID (see
- * __ip_select_ident() in net/ipv4/route.c).
* Nodes are removed only when reference counter goes to 0.
* When it's happened the node may be removed when a sufficient amount of
* time has been passed since its last use. The less-recently-used entry can
@@ -62,7 +49,6 @@
* refcnt: atomically against modifications on other CPU;
* usually under some other lock to prevent node disappearing
* daddr: unchangeable
- * ip_id_count: atomic value (no lock needed)
*/
static struct kmem_cache *peer_cachep __read_mostly;
@@ -497,10 +483,6 @@ relookup:
p->daddr = *daddr;
atomic_set(&p->refcnt, 1);
atomic_set(&p->rid, 0);
- atomic_set(&p->ip_id_count,
- (daddr->family == AF_INET) ?
- secure_ip_id(daddr->addr.a4) :
- secure_ipv6_id(daddr->addr.a6));
p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
p->rate_tokens = 0;
/* 60*HZ is arbitrary, but chosen enough high so that the first
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 6e231ab58d65..8d3b6b0e9857 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -148,7 +148,7 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
iph->saddr = saddr;
iph->protocol = sk->sk_protocol;
- ip_select_ident(skb, &rt->dst, sk);
+ ip_select_ident(skb, sk);
if (opt && opt->opt.optlen) {
iph->ihl += opt->opt.optlen>>2;
@@ -430,8 +430,7 @@ packet_routed:
ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
}
- ip_select_ident_more(skb, &rt->dst, sk,
- (skb_shinfo(skb)->gso_segs ?: 1) - 1);
+ ip_select_ident_segs(skb, sk, skb_shinfo(skb)->gso_segs ?: 1);
/* TODO : should we use skb->sk here instead of sk ? */
skb->priority = sk->sk_priority;
@@ -1379,7 +1378,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
iph->ttl = ttl;
iph->protocol = sk->sk_protocol;
ip_copy_addrs(iph, fl4);
- ip_select_ident(skb, &rt->dst, sk);
+ ip_select_ident(skb, sk);
if (opt) {
iph->ihl += opt->optlen>>2;
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index bcf206c79005..847e69cbff7e 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -74,7 +74,7 @@ int iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
iph->daddr = dst;
iph->saddr = src;
iph->ttl = ttl;
- __ip_select_ident(iph, &rt->dst, (skb_shinfo(skb)->gso_segs ?: 1) - 1);
+ __ip_select_ident(iph, skb_shinfo(skb)->gso_segs ?: 1);
err = ip_local_out_sk(sk, skb);
if (unlikely(net_xmit_eval(err)))
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 2bc9cc47f246..65bcaa789043 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1663,7 +1663,7 @@ static void ip_encap(struct sk_buff *skb, __be32 saddr, __be32 daddr)
iph->protocol = IPPROTO_IPIP;
iph->ihl = 5;
iph->tot_len = htons(skb->len);
- ip_select_ident(skb, skb_dst(skb), NULL);
+ ip_select_ident(skb, NULL);
ip_send_check(iph);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index a9dbe58bdfe7..2c65160565e1 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -389,7 +389,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
iph->check = 0;
iph->tot_len = htons(length);
if (!iph->id)
- ip_select_ident(skb, &rt->dst, NULL);
+ ip_select_ident(skb, NULL);
iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
}
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 4154eb76b0ad..082239ffe34a 100644
--- 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>
@@ -456,39 +457,19 @@ 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.
- */
-static void ip_select_fb_ident(struct iphdr *iph)
-{
- static DEFINE_SPINLOCK(ip_fb_id_lock);
- static u32 ip_fallback_id;
- u32 salt;
+atomic_t *ip_idents __read_mostly;
+EXPORT_SYMBOL(ip_idents);
- 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);
-}
-
-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;
+ 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;
- }
+ net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
- ip_select_fb_ident(iph);
+ hash = jhash_1word((__force u32)iph->daddr, ip_idents_hashrnd);
+ id = ip_idents_reserve(hash, segs);
+ iph->id = htons(id);
}
EXPORT_SYMBOL(__ip_select_ident);
@@ -2711,6 +2692,12 @@ 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)
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index 05f2b484954f..91771a7c802f 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -58,12 +58,12 @@ static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
- ip_select_ident(skb, dst->child, NULL);
top_iph->ttl = ip4_dst_hoplimit(dst->child);
top_iph->saddr = x->props.saddr.a4;
top_iph->daddr = x->id.daddr.a4;
+ ip_select_ident(skb, NULL);
return 0;
}