summaryrefslogtreecommitdiff
path: root/net/sched/act_skbmod.c
blob: d227599f7e73381cb56a5b4516ae36ef2f02ef1f (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
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
/*
 * net/sched/act_skbmod.c  skb data modifier
 *
 * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com>
 *
 * 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.
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>

#include <linux/tc_act/tc_skbmod.h>
#include <net/tc_act/tc_skbmod.h>

static unsigned int skbmod_net_id;
static struct tc_action_ops act_skbmod_ops;

#define MAX_EDIT_LEN ETH_HLEN
static int tcf_skbmod_run(struct sk_buff *skb, const struct tc_action *a,
			  struct tcf_result *res)
{
	struct tcf_skbmod *d = to_skbmod(a);
	int action;
	struct tcf_skbmod_params *p;
	u64 flags;
	int err;

	tcf_lastuse_update(&d->tcf_tm);
	bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);

	/* XXX: if you are going to edit more fields beyond ethernet header
	 * (example when you add IP header replacement or vlan swap)
	 * then MAX_EDIT_LEN needs to change appropriately
	*/
	err = skb_ensure_writable(skb, MAX_EDIT_LEN);
	if (unlikely(err)) { /* best policy is to drop on the floor */
		qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
		return TC_ACT_SHOT;
	}

	rcu_read_lock();
	action = READ_ONCE(d->tcf_action);
	if (unlikely(action == TC_ACT_SHOT)) {
		qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
		rcu_read_unlock();
		return action;
	}

	p = rcu_dereference(d->skbmod_p);
	flags = p->flags;
	if (flags & SKBMOD_F_DMAC)
		ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
	if (flags & SKBMOD_F_SMAC)
		ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
	if (flags & SKBMOD_F_ETYPE)
		eth_hdr(skb)->h_proto = p->eth_type;
	rcu_read_unlock();

	if (flags & SKBMOD_F_SWAPMAC) {
		u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
		/*XXX: I am sure we can come up with more efficient swapping*/
		ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
		ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
		ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
	}

	return action;
}

static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
	[TCA_SKBMOD_PARMS]		= { .len = sizeof(struct tc_skbmod) },
	[TCA_SKBMOD_DMAC]		= { .len = ETH_ALEN },
	[TCA_SKBMOD_SMAC]		= { .len = ETH_ALEN },
	[TCA_SKBMOD_ETYPE]		= { .type = NLA_U16 },
};

static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
			   struct nlattr *est, struct tc_action **a,
			   int ovr, int bind)
{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
	struct nlattr *tb[TCA_SKBMOD_MAX + 1];
	struct tcf_skbmod_params *p, *p_old;
	struct tc_skbmod *parm;
	struct tcf_skbmod *d;
	bool exists = false;
	u8 *daddr = NULL;
	u8 *saddr = NULL;
	u16 eth_type = 0;
	u32 lflags = 0;
	int ret = 0, err;

	if (!nla)
		return -EINVAL;

	err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL);
	if (err < 0)
		return err;

	if (!tb[TCA_SKBMOD_PARMS])
		return -EINVAL;

	if (tb[TCA_SKBMOD_DMAC]) {
		daddr = nla_data(tb[TCA_SKBMOD_DMAC]);
		lflags |= SKBMOD_F_DMAC;
	}

	if (tb[TCA_SKBMOD_SMAC]) {
		saddr = nla_data(tb[TCA_SKBMOD_SMAC]);
		lflags |= SKBMOD_F_SMAC;
	}

	if (tb[TCA_SKBMOD_ETYPE]) {
		eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]);
		lflags |= SKBMOD_F_ETYPE;
	}

	parm = nla_data(tb[TCA_SKBMOD_PARMS]);
	if (parm->flags & SKBMOD_F_SWAPMAC)
		lflags = SKBMOD_F_SWAPMAC;

	exists = tcf_idr_check(tn, parm->index, a, bind);
	if (exists && bind)
		return 0;

	if (!lflags) {
		if (exists)
			tcf_idr_release(*a, bind);
		return -EINVAL;
	}

	if (!exists) {
		ret = tcf_idr_create(tn, parm->index, est, a,
				     &act_skbmod_ops, bind, true);
		if (ret)
			return ret;

		ret = ACT_P_CREATED;
	} else {
		tcf_idr_release(*a, bind);
		if (!ovr)
			return -EEXIST;
	}

	d = to_skbmod(*a);

	ASSERT_RTNL();
	p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
	if (unlikely(!p)) {
		if (ret == ACT_P_CREATED)
			tcf_idr_release(*a, bind);
		return -ENOMEM;
	}

	p->flags = lflags;
	d->tcf_action = parm->action;

	p_old = rtnl_dereference(d->skbmod_p);

	if (ovr)
		spin_lock_bh(&d->tcf_lock);

	if (lflags & SKBMOD_F_DMAC)
		ether_addr_copy(p->eth_dst, daddr);
	if (lflags & SKBMOD_F_SMAC)
		ether_addr_copy(p->eth_src, saddr);
	if (lflags & SKBMOD_F_ETYPE)
		p->eth_type = htons(eth_type);

	rcu_assign_pointer(d->skbmod_p, p);
	if (ovr)
		spin_unlock_bh(&d->tcf_lock);

	if (p_old)
		kfree_rcu(p_old, rcu);

	if (ret == ACT_P_CREATED)
		tcf_idr_insert(tn, *a);
	return ret;
}

static void tcf_skbmod_cleanup(struct tc_action *a, int bind)
{
	struct tcf_skbmod *d = to_skbmod(a);
	struct tcf_skbmod_params  *p;

	p = rcu_dereference_protected(d->skbmod_p, 1);
	if (p)
		kfree_rcu(p, rcu);
}

static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
			   int bind, int ref)
{
	struct tcf_skbmod *d = to_skbmod(a);
	unsigned char *b = skb_tail_pointer(skb);
	struct tcf_skbmod_params  *p = rtnl_dereference(d->skbmod_p);
	struct tc_skbmod opt = {
		.index   = d->tcf_index,
		.refcnt  = d->tcf_refcnt - ref,
		.bindcnt = d->tcf_bindcnt - bind,
		.action  = d->tcf_action,
	};
	struct tcf_t t;

	opt.flags  = p->flags;
	if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
		goto nla_put_failure;
	if ((p->flags & SKBMOD_F_DMAC) &&
	    nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
		goto nla_put_failure;
	if ((p->flags & SKBMOD_F_SMAC) &&
	    nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
		goto nla_put_failure;
	if ((p->flags & SKBMOD_F_ETYPE) &&
	    nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
		goto nla_put_failure;

	tcf_tm_dump(&t, &d->tcf_tm);
	if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
		goto nla_put_failure;

	return skb->len;
nla_put_failure:
	nlmsg_trim(skb, b);
	return -1;
}

static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
			     struct netlink_callback *cb, int type,
			     const struct tc_action_ops *ops)
{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

	return tcf_generic_walker(tn, skb, cb, type, ops);
}

static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index)
{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

	return tcf_idr_search(tn, a, index);
}

static struct tc_action_ops act_skbmod_ops = {
	.kind		=	"skbmod",
	.type		=	TCA_ACT_SKBMOD,
	.owner		=	THIS_MODULE,
	.act		=	tcf_skbmod_run,
	.dump		=	tcf_skbmod_dump,
	.init		=	tcf_skbmod_init,
	.cleanup	=	tcf_skbmod_cleanup,
	.walk		=	tcf_skbmod_walker,
	.lookup		=	tcf_skbmod_search,
	.size		=	sizeof(struct tcf_skbmod),
};

static __net_init int skbmod_init_net(struct net *net)
{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

	return tc_action_net_init(tn, &act_skbmod_ops);
}

static void __net_exit skbmod_exit_net(struct net *net)
{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

	tc_action_net_exit(tn);
}

static struct pernet_operations skbmod_net_ops = {
	.init = skbmod_init_net,
	.exit = skbmod_exit_net,
	.id   = &skbmod_net_id,
	.size = sizeof(struct tc_action_net),
};

MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
MODULE_DESCRIPTION("SKB data mod-ing");
MODULE_LICENSE("GPL");

static int __init skbmod_init_module(void)
{
	return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
}

static void __exit skbmod_cleanup_module(void)
{
	tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
}

module_init(skbmod_init_module);
module_exit(skbmod_cleanup_module);