--- /dev/null
+/*
+ * 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);
Code Review / kvmfornfv.git / blobdiff