summaryrefslogtreecommitdiff
path: root/net/ipv4/inet_fragment.c
blob: bcb11f3a27c0c34115af05034a5a20f57842eb0a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
/*
 * 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 <linux/rhashtable.h>

#include <net/sock.h>
#include <net/inet_frag.h>
#include <net/inet_ecn.h>

/* 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);

int inet_frags_init(struct inet_frags *f)
{
	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_fini(struct inet_frags *f)
{
	/* We must wait that all inet_frag_destroy_rcu() have completed. */
	rcu_barrier();

	kmem_cache_destroy(f->frags_cachep);
	f->frags_cachep = NULL;
}
EXPORT_SYMBOL(inet_frags_fini);

static void inet_frags_free_cb(void *ptr, void *arg)
{
	struct inet_frag_queue *fq = ptr;

	/* If we can not cancel the timer, it means this frag_queue
	 * is already disappearing, we have nothing to do.
	 * Otherwise, we own a refcount until the end of this function.
	 */
	if (!del_timer(&fq->timer))
		return;

	spin_lock_bh(&fq->lock);
	if (!(fq->flags & INET_FRAG_COMPLETE)) {
		fq->flags |= INET_FRAG_COMPLETE;
		refcount_dec(&fq->refcnt);
	}
	spin_unlock_bh(&fq->lock);

	inet_frag_put(fq);
}

void inet_frags_exit_net(struct netns_frags *nf)
{
	nf->high_thresh = 0; /* prevent creation of new frags */

	rhashtable_free_and_destroy(&nf->rhashtable, inet_frags_free_cb, NULL);
}
EXPORT_SYMBOL(inet_frags_exit_net);

void inet_frag_kill(struct inet_frag_queue *fq)
{
	if (del_timer(&fq->timer))
		refcount_dec(&fq->refcnt);

	if (!(fq->flags & INET_FRAG_COMPLETE)) {
		struct netns_frags *nf = fq->net;

		fq->flags |= INET_FRAG_COMPLETE;
		rhashtable_remove_fast(&nf->rhashtable, &fq->node, nf->f->rhash_params);
		refcount_dec(&fq->refcnt);
	}
}
EXPORT_SYMBOL(inet_frag_kill);

static void inet_frag_destroy_rcu(struct rcu_head *head)
{
	struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
						 rcu);
	struct inet_frags *f = q->net->f;

	if (f->destructor)
		f->destructor(q);
	kmem_cache_free(f->frags_cachep, q);
}

void inet_frag_destroy(struct inet_frag_queue *q)
{
	struct sk_buff *fp;
	struct netns_frags *nf;
	unsigned int sum, sum_truesize = 0;
	struct inet_frags *f;

	WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
	WARN_ON(del_timer(&q->timer) != 0);

	/* Release all fragment data. */
	fp = q->fragments;
	nf = q->net;
	f = nf->f;
	if (fp) {
		do {
			struct sk_buff *xp = fp->next;

			sum_truesize += fp->truesize;
			kfree_skb(fp);
			fp = xp;
		} while (fp);
	} else {
		sum_truesize = inet_frag_rbtree_purge(&q->rb_fragments);
	}
	sum = sum_truesize + f->qsize;

	call_rcu(&q->rcu, inet_frag_destroy_rcu);

	sub_frag_mem_limit(nf, sum);
}
EXPORT_SYMBOL(inet_frag_destroy);

static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
					       struct inet_frags *f,
					       void *arg)
{
	struct inet_frag_queue *q;

	q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
	if (!q)
		return NULL;

	q->net = nf;
	f->constructor(q, arg);
	add_frag_mem_limit(nf, f->qsize);

	timer_setup(&q->timer, f->frag_expire, 0);
	spin_lock_init(&q->lock);
	refcount_set(&q->refcnt, 3);

	return q;
}

static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
						void *arg)
{
	struct inet_frags *f = nf->f;
	struct inet_frag_queue *q;
	int err;

	q = inet_frag_alloc(nf, f, arg);
	if (!q)
		return NULL;

	mod_timer(&q->timer, jiffies + nf->timeout);

	err = rhashtable_insert_fast(&nf->rhashtable, &q->node,
				     f->rhash_params);
	if (err < 0) {
		q->flags |= INET_FRAG_COMPLETE;
		inet_frag_kill(q);
		inet_frag_destroy(q);
		return NULL;
	}
	return q;
}

/* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, void *key)
{
	struct inet_frag_queue *fq;

	if (!nf->high_thresh || frag_mem_limit(nf) > nf->high_thresh)
		return NULL;

	rcu_read_lock();

	fq = rhashtable_lookup(&nf->rhashtable, key, nf->f->rhash_params);
	if (fq) {
		if (!refcount_inc_not_zero(&fq->refcnt))
			fq = NULL;
		rcu_read_unlock();
		return fq;
	}
	rcu_read_unlock();

	return inet_frag_create(nf, key);
}
EXPORT_SYMBOL(inet_frag_find);