/* * 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 <net/inet_frag.h> static void inet_frag_secret_rebuild(unsigned long dummy) { struct inet_frags *f = (struct inet_frags *)dummy; unsigned long now = jiffies; int i; write_lock(&f->lock); get_random_bytes(&f->rnd, sizeof(u32)); for (i = 0; i < INETFRAGS_HASHSZ; i++) { struct inet_frag_queue *q; struct hlist_node *p, *n; hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) { unsigned int hval = f->hashfn(q); if (hval != i) { hlist_del(&q->list); /* Relink to new hash chain. */ hlist_add_head(&q->list, &f->hash[hval]); } } } write_unlock(&f->lock); mod_timer(&f->secret_timer, now + f->ctl->secret_interval); } void inet_frags_init(struct inet_frags *f) { int i; for (i = 0; i < INETFRAGS_HASHSZ; i++) INIT_HLIST_HEAD(&f->hash[i]); INIT_LIST_HEAD(&f->lru_list); rwlock_init(&f->lock); f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ (jiffies ^ (jiffies >> 6))); f->nqueues = 0; atomic_set(&f->mem, 0); setup_timer(&f->secret_timer, inet_frag_secret_rebuild, (unsigned long)f); f->secret_timer.expires = jiffies + f->ctl->secret_interval; add_timer(&f->secret_timer); } EXPORT_SYMBOL(inet_frags_init); void inet_frags_fini(struct inet_frags *f) { del_timer(&f->secret_timer); } EXPORT_SYMBOL(inet_frags_fini); static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) { write_lock(&f->lock); hlist_del(&fq->list); list_del(&fq->lru_list); f->nqueues--; write_unlock(&f->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->last_in & COMPLETE)) { fq_unlink(fq, f); atomic_dec(&fq->refcnt); fq->last_in |= COMPLETE; } } EXPORT_SYMBOL(inet_frag_kill); static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb, int *work) { if (work) *work -= skb->truesize; atomic_sub(skb->truesize, &f->mem); if (f->skb_free) f->skb_free(skb); kfree_skb(skb); } void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f, int *work) { struct sk_buff *fp; BUG_TRAP(q->last_in & COMPLETE); BUG_TRAP(del_timer(&q->timer) == 0); /* Release all fragment data. */ fp = q->fragments; while (fp) { struct sk_buff *xp = fp->next; frag_kfree_skb(f, fp, work); fp = xp; } if (work) *work -= f->qsize; atomic_sub(f->qsize, &f->mem); if (f->destructor) f->destructor(q); kfree(q); } EXPORT_SYMBOL(inet_frag_destroy); int inet_frag_evictor(struct inet_frags *f) { struct inet_frag_queue *q; int work, evicted = 0; work = atomic_read(&f->mem) - f->ctl->low_thresh; while (work > 0) { read_lock(&f->lock); if (list_empty(&f->lru_list)) { read_unlock(&f->lock); break; } q = list_first_entry(&f->lru_list, struct inet_frag_queue, lru_list); atomic_inc(&q->refcnt); read_unlock(&f->lock); spin_lock(&q->lock); if (!(q->last_in & COMPLETE)) inet_frag_kill(q, f); spin_unlock(&q->lock); if (atomic_dec_and_test(&q->refcnt)) inet_frag_destroy(q, f, &work); evicted++; } return evicted; } EXPORT_SYMBOL(inet_frag_evictor); static struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *qp_in, struct inet_frags *f, unsigned int hash, void *arg) { struct inet_frag_queue *qp; #ifdef CONFIG_SMP struct hlist_node *n; #endif write_lock(&f->lock); #ifdef CONFIG_SMP /* With SMP race we have to recheck hash table, because * such entry could be created on other cpu, while we * promoted read lock to write lock. */ hlist_for_each_entry(qp, n, &f->hash[hash], list) { if (f->match(qp, arg)) { atomic_inc(&qp->refcnt); write_unlock(&f->lock); qp_in->last_in |= COMPLETE; inet_frag_put(qp_in, f); return qp; } } #endif qp = qp_in; if (!mod_timer(&qp->timer, jiffies + f->ctl->timeout)) atomic_inc(&qp->refcnt); atomic_inc(&qp->refcnt); hlist_add_head(&qp->list, &f->hash[hash]); list_add_tail(&qp->lru_list, &f->lru_list); f->nqueues++; write_unlock(&f->lock); return qp; } static struct inet_frag_queue *inet_frag_alloc(struct inet_frags *f, void *arg) { struct inet_frag_queue *q; q = kzalloc(f->qsize, GFP_ATOMIC); if (q == NULL) return NULL; f->constructor(q, arg); atomic_add(f->qsize, &f->mem); 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 inet_frags *f, void *arg, unsigned int hash) { struct inet_frag_queue *q; q = inet_frag_alloc(f, arg); if (q == NULL) return NULL; return inet_frag_intern(q, f, hash, arg); } struct inet_frag_queue *inet_frag_find(struct inet_frags *f, void *key, unsigned int hash) { struct inet_frag_queue *q; struct hlist_node *n; read_lock(&f->lock); hlist_for_each_entry(q, n, &f->hash[hash], list) { if (f->match(q, key)) { atomic_inc(&q->refcnt); read_unlock(&f->lock); return q; } } read_unlock(&f->lock); return inet_frag_create(f, key, hash); } EXPORT_SYMBOL(inet_frag_find);