1 files changed, 463 insertions, 0 deletions

diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
new file mode 100644
index 000000000..5e346a082
--- /dev/null
+++ b/net/ipv4/inet_fragment.c
@@ -0,0 +1,463 @@
+/*
+ * inet fragments management
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * 		Authors:	Pavel Emelyanov <xemul@openvz.org>
+ *				Started as consolidation of ipv4/ip_fragment.c,
+ *				ipv6/reassembly. and ipv6 nf conntrack reassembly
+ */
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+
+#include <net/sock.h>
+#include <net/inet_frag.h>
+#include <net/inet_ecn.h>
+
+#define INETFRAGS_EVICT_BUCKETS   128
+#define INETFRAGS_EVICT_MAX	  512
+
+/* don't rebuild inetfrag table with new secret more often than this */
+#define INETFRAGS_MIN_REBUILD_INTERVAL (5 * HZ)
+
+/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
+ * Value : 0xff if frame should be dropped.
+ *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
+ */
+const u8 ip_frag_ecn_table[16] = {
+	/* at least one fragment had CE, and others ECT_0 or ECT_1 */
+	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0]			= INET_ECN_CE,
+	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1]			= INET_ECN_CE,
+	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1]	= INET_ECN_CE,
+
+	/* invalid combinations : drop frame */
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
+	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
+};
+EXPORT_SYMBOL(ip_frag_ecn_table);
+
+static unsigned int
+inet_frag_hashfn(const struct inet_frags *f, const struct inet_frag_queue *q)
+{
+	return f->hashfn(q) & (INETFRAGS_HASHSZ - 1);
+}
+
+static bool inet_frag_may_rebuild(struct inet_frags *f)
+{
+	return time_after(jiffies,
+	       f->last_rebuild_jiffies + INETFRAGS_MIN_REBUILD_INTERVAL);
+}
+
+static void inet_frag_secret_rebuild(struct inet_frags *f)
+{
+	int i;
+
+	write_seqlock_bh(&f->rnd_seqlock);
+
+	if (!inet_frag_may_rebuild(f))
+		goto out;
+
+	get_random_bytes(&f->rnd, sizeof(u32));
+
+	for (i = 0; i < INETFRAGS_HASHSZ; i++) {
+		struct inet_frag_bucket *hb;
+		struct inet_frag_queue *q;
+		struct hlist_node *n;
+
+		hb = &f->hash[i];
+		spin_lock(&hb->chain_lock);
+
+		hlist_for_each_entry_safe(q, n, &hb->chain, list) {
+			unsigned int hval = inet_frag_hashfn(f, q);
+
+			if (hval != i) {
+				struct inet_frag_bucket *hb_dest;
+
+				hlist_del(&q->list);
+
+				/* Relink to new hash chain. */
+				hb_dest = &f->hash[hval];
+
+				/* This is the only place where we take
+				 * another chain_lock while already holding
+				 * one.  As this will not run concurrently,
+				 * we cannot deadlock on hb_dest lock below, if its
+				 * already locked it will be released soon since
+				 * other caller cannot be waiting for hb lock
+				 * that we've taken above.
+				 */
+				spin_lock_nested(&hb_dest->chain_lock,
+						 SINGLE_DEPTH_NESTING);
+				hlist_add_head(&q->list, &hb_dest->chain);
+				spin_unlock(&hb_dest->chain_lock);
+			}
+		}
+		spin_unlock(&hb->chain_lock);
+	}
+
+	f->rebuild = false;
+	f->last_rebuild_jiffies = jiffies;
+out:
+	write_sequnlock_bh(&f->rnd_seqlock);
+}
+
+static bool inet_fragq_should_evict(const struct inet_frag_queue *q)
+{
+	return q->net->low_thresh == 0 ||
+	       frag_mem_limit(q->net) >= q->net->low_thresh;
+}
+
+static unsigned int
+inet_evict_bucket(struct inet_frags *f, struct inet_frag_bucket *hb)
+{
+	struct inet_frag_queue *fq;
+	struct hlist_node *n;
+	unsigned int evicted = 0;
+	HLIST_HEAD(expired);
+
+evict_again:
+	spin_lock(&hb->chain_lock);
+
+	hlist_for_each_entry_safe(fq, n, &hb->chain, list) {
+		if (!inet_fragq_should_evict(fq))
+			continue;
+
+		if (!del_timer(&fq->timer)) {
+			/* q expiring right now thus increment its refcount so
+			 * it won't be freed under us and wait until the timer
+			 * has finished executing then destroy it
+			 */
+			atomic_inc(&fq->refcnt);
+			spin_unlock(&hb->chain_lock);
+			del_timer_sync(&fq->timer);
+			inet_frag_put(fq, f);
+			goto evict_again;
+		}
+
+		fq->flags |= INET_FRAG_EVICTED;
+		hlist_del(&fq->list);
+		hlist_add_head(&fq->list, &expired);
+		++evicted;
+	}
+
+	spin_unlock(&hb->chain_lock);
+
+	hlist_for_each_entry_safe(fq, n, &expired, list)
+		f->frag_expire((unsigned long) fq);
+
+	return evicted;
+}
+
+static void inet_frag_worker(struct work_struct *work)
+{
+	unsigned int budget = INETFRAGS_EVICT_BUCKETS;
+	unsigned int i, evicted = 0;
+	struct inet_frags *f;
+
+	f = container_of(work, struct inet_frags, frags_work);
+
+	BUILD_BUG_ON(INETFRAGS_EVICT_BUCKETS >= INETFRAGS_HASHSZ);
+
+	local_bh_disable();
+
+	for (i = ACCESS_ONCE(f->next_bucket); budget; --budget) {
+		evicted += inet_evict_bucket(f, &f->hash[i]);
+		i = (i + 1) & (INETFRAGS_HASHSZ - 1);
+		if (evicted > INETFRAGS_EVICT_MAX)
+			break;
+	}
+
+	f->next_bucket = i;
+
+	local_bh_enable();
+
+	if (f->rebuild && inet_frag_may_rebuild(f))
+		inet_frag_secret_rebuild(f);
+}
+
+static void inet_frag_schedule_worker(struct inet_frags *f)
+{
+	if (unlikely(!work_pending(&f->frags_work)))
+		schedule_work(&f->frags_work);
+}
+
+int inet_frags_init(struct inet_frags *f)
+{
+	int i;
+
+	INIT_WORK(&f->frags_work, inet_frag_worker);
+
+	for (i = 0; i < INETFRAGS_HASHSZ; i++) {
+		struct inet_frag_bucket *hb = &f->hash[i];
+
+		spin_lock_init(&hb->chain_lock);
+		INIT_HLIST_HEAD(&hb->chain);
+	}
+
+	seqlock_init(&f->rnd_seqlock);
+	f->last_rebuild_jiffies = 0;
+	f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
+					    NULL);
+	if (!f->frags_cachep)
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL(inet_frags_init);
+
+void inet_frags_init_net(struct netns_frags *nf)
+{
+	init_frag_mem_limit(nf);
+}
+EXPORT_SYMBOL(inet_frags_init_net);
+
+void inet_frags_fini(struct inet_frags *f)
+{
+	cancel_work_sync(&f->frags_work);
+	kmem_cache_destroy(f->frags_cachep);
+}
+EXPORT_SYMBOL(inet_frags_fini);
+
+void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
+{
+	unsigned int seq;
+	int i;
+
+	nf->low_thresh = 0;
+	local_bh_disable();
+
+evict_again:
+	seq = read_seqbegin(&f->rnd_seqlock);
+
+	for (i = 0; i < INETFRAGS_HASHSZ ; i++)
+		inet_evict_bucket(f, &f->hash[i]);
+
+	if (read_seqretry(&f->rnd_seqlock, seq))
+		goto evict_again;
+
+	local_bh_enable();
+
+	percpu_counter_destroy(&nf->mem);
+}
+EXPORT_SYMBOL(inet_frags_exit_net);
+
+static struct inet_frag_bucket *
+get_frag_bucket_locked(struct inet_frag_queue *fq, struct inet_frags *f)
+__acquires(hb->chain_lock)
+{
+	struct inet_frag_bucket *hb;
+	unsigned int seq, hash;
+
+ restart:
+	seq = read_seqbegin(&f->rnd_seqlock);
+
+	hash = inet_frag_hashfn(f, fq);
+	hb = &f->hash[hash];
+
+	spin_lock(&hb->chain_lock);
+	if (read_seqretry(&f->rnd_seqlock, seq)) {
+		spin_unlock(&hb->chain_lock);
+		goto restart;
+	}
+
+	return hb;
+}
+
+static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
+{
+	struct inet_frag_bucket *hb;
+
+	hb = get_frag_bucket_locked(fq, f);
+	if (!(fq->flags & INET_FRAG_EVICTED))
+		hlist_del(&fq->list);
+	spin_unlock(&hb->chain_lock);
+}
+
+void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
+{
+	if (del_timer(&fq->timer))
+		atomic_dec(&fq->refcnt);
+
+	if (!(fq->flags & INET_FRAG_COMPLETE)) {
+		fq_unlink(fq, f);
+		atomic_dec(&fq->refcnt);
+		fq->flags |= INET_FRAG_COMPLETE;
+	}
+}
+EXPORT_SYMBOL(inet_frag_kill);
+
+static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f,
+				  struct sk_buff *skb)
+{
+	if (f->skb_free)
+		f->skb_free(skb);
+	kfree_skb(skb);
+}
+
+void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f)
+{
+	struct sk_buff *fp;
+	struct netns_frags *nf;
+	unsigned int sum, sum_truesize = 0;
+
+	WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
+	WARN_ON(del_timer(&q->timer) != 0);
+
+	/* Release all fragment data. */
+	fp = q->fragments;
+	nf = q->net;
+	while (fp) {
+		struct sk_buff *xp = fp->next;
+
+		sum_truesize += fp->truesize;
+		frag_kfree_skb(nf, f, fp);
+		fp = xp;
+	}
+	sum = sum_truesize + f->qsize;
+	sub_frag_mem_limit(q, sum);
+
+	if (f->destructor)
+		f->destructor(q);
+	kmem_cache_free(f->frags_cachep, q);
+}
+EXPORT_SYMBOL(inet_frag_destroy);
+
+static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
+						struct inet_frag_queue *qp_in,
+						struct inet_frags *f,
+						void *arg)
+{
+	struct inet_frag_bucket *hb = get_frag_bucket_locked(qp_in, f);
+	struct inet_frag_queue *qp;
+
+#ifdef CONFIG_SMP
+	/* With SMP race we have to recheck hash table, because
+	 * such entry could have been created on other cpu before
+	 * we acquired hash bucket lock.
+	 */
+	hlist_for_each_entry(qp, &hb->chain, list) {
+		if (qp->net == nf && f->match(qp, arg)) {
+			atomic_inc(&qp->refcnt);
+			spin_unlock(&hb->chain_lock);
+			qp_in->flags |= INET_FRAG_COMPLETE;
+			inet_frag_put(qp_in, f);
+			return qp;
+		}
+	}
+#endif
+	qp = qp_in;
+	if (!mod_timer(&qp->timer, jiffies + nf->timeout))
+		atomic_inc(&qp->refcnt);
+
+	atomic_inc(&qp->refcnt);
+	hlist_add_head(&qp->list, &hb->chain);
+
+	spin_unlock(&hb->chain_lock);
+
+	return qp;
+}
+
+static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
+					       struct inet_frags *f,
+					       void *arg)
+{
+	struct inet_frag_queue *q;
+
+	if (frag_mem_limit(nf) > nf->high_thresh) {
+		inet_frag_schedule_worker(f);
+		return NULL;
+	}
+
+	q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
+	if (!q)
+		return NULL;
+
+	q->net = nf;
+	f->constructor(q, arg);
+	add_frag_mem_limit(q, f->qsize);
+
+	setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
+	spin_lock_init(&q->lock);
+	atomic_set(&q->refcnt, 1);
+
+	return q;
+}
+
+static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
+						struct inet_frags *f,
+						void *arg)
+{
+	struct inet_frag_queue *q;
+
+	q = inet_frag_alloc(nf, f, arg);
+	if (!q)
+		return NULL;
+
+	return inet_frag_intern(nf, q, f, arg);
+}
+
+struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
+				       struct inet_frags *f, void *key,
+				       unsigned int hash)
+{
+	struct inet_frag_bucket *hb;
+	struct inet_frag_queue *q;
+	int depth = 0;
+
+	if (frag_mem_limit(nf) > nf->low_thresh)
+		inet_frag_schedule_worker(f);
+
+	hash &= (INETFRAGS_HASHSZ - 1);
+	hb = &f->hash[hash];
+
+	spin_lock(&hb->chain_lock);
+	hlist_for_each_entry(q, &hb->chain, list) {
+		if (q->net == nf && f->match(q, key)) {
+			atomic_inc(&q->refcnt);
+			spin_unlock(&hb->chain_lock);
+			return q;
+		}
+		depth++;
+	}
+	spin_unlock(&hb->chain_lock);
+
+	if (depth <= INETFRAGS_MAXDEPTH)
+		return inet_frag_create(nf, f, key);
+
+	if (inet_frag_may_rebuild(f)) {
+		if (!f->rebuild)
+			f->rebuild = true;
+		inet_frag_schedule_worker(f);
+	}
+
+	return ERR_PTR(-ENOBUFS);
+}
+EXPORT_SYMBOL(inet_frag_find);
+
+void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
+				   const char *prefix)
+{
+	static const char msg[] = "inet_frag_find: Fragment hash bucket"
+		" list length grew over limit " __stringify(INETFRAGS_MAXDEPTH)
+		". Dropping fragment.\n";
+
+	if (PTR_ERR(q) == -ENOBUFS)
+		net_dbg_ratelimited("%s%s", prefix, msg);
+}
+EXPORT_SYMBOL(inet_frag_maybe_warn_overflow);