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1 /*
2 * net/sched/act_skbmod.c skb data modifier
3 *
4 * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
16 #include <linux/rtnetlink.h>
17 #include <net/netlink.h>
18 #include <net/pkt_sched.h>
19
20 #include <linux/tc_act/tc_skbmod.h>
21 #include <net/tc_act/tc_skbmod.h>
22
23 #define SKBMOD_TAB_MASK 15
24
25 static unsigned int skbmod_net_id;
26 static struct tc_action_ops act_skbmod_ops;
27
28 #define MAX_EDIT_LEN ETH_HLEN
29 static int tcf_skbmod_run(struct sk_buff *skb, const struct tc_action *a,
30 struct tcf_result *res)
31 {
32 struct tcf_skbmod *d = to_skbmod(a);
33 int action;
34 struct tcf_skbmod_params *p;
35 u64 flags;
36 int err;
37
38 tcf_lastuse_update(&d->tcf_tm);
39 bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);
40
41 /* XXX: if you are going to edit more fields beyond ethernet header
42 * (example when you add IP header replacement or vlan swap)
43 * then MAX_EDIT_LEN needs to change appropriately
44 */
45 err = skb_ensure_writable(skb, MAX_EDIT_LEN);
46 if (unlikely(err)) { /* best policy is to drop on the floor */
47 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
48 return TC_ACT_SHOT;
49 }
50
51 rcu_read_lock();
52 action = READ_ONCE(d->tcf_action);
53 if (unlikely(action == TC_ACT_SHOT)) {
54 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
55 rcu_read_unlock();
56 return action;
57 }
58
59 p = rcu_dereference(d->skbmod_p);
60 flags = p->flags;
61 if (flags & SKBMOD_F_DMAC)
62 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
63 if (flags & SKBMOD_F_SMAC)
64 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
65 if (flags & SKBMOD_F_ETYPE)
66 eth_hdr(skb)->h_proto = p->eth_type;
67 rcu_read_unlock();
68
69 if (flags & SKBMOD_F_SWAPMAC) {
70 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
71 /*XXX: I am sure we can come up with more efficient swapping*/
72 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
73 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
74 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
75 }
76
77 return action;
78 }
79
80 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
81 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) },
82 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN },
83 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN },
84 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 },
85 };
86
87 static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
88 struct nlattr *est, struct tc_action **a,
89 int ovr, int bind)
90 {
91 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
92 struct nlattr *tb[TCA_SKBMOD_MAX + 1];
93 struct tcf_skbmod_params *p, *p_old;
94 struct tc_skbmod *parm;
95 struct tcf_skbmod *d;
96 bool exists = false;
97 u8 *daddr = NULL;
98 u8 *saddr = NULL;
99 u16 eth_type = 0;
100 u32 lflags = 0;
101 int ret = 0, err;
102
103 if (!nla)
104 return -EINVAL;
105
106 err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL);
107 if (err < 0)
108 return err;
109
110 if (!tb[TCA_SKBMOD_PARMS])
111 return -EINVAL;
112
113 if (tb[TCA_SKBMOD_DMAC]) {
114 daddr = nla_data(tb[TCA_SKBMOD_DMAC]);
115 lflags |= SKBMOD_F_DMAC;
116 }
117
118 if (tb[TCA_SKBMOD_SMAC]) {
119 saddr = nla_data(tb[TCA_SKBMOD_SMAC]);
120 lflags |= SKBMOD_F_SMAC;
121 }
122
123 if (tb[TCA_SKBMOD_ETYPE]) {
124 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]);
125 lflags |= SKBMOD_F_ETYPE;
126 }
127
128 parm = nla_data(tb[TCA_SKBMOD_PARMS]);
129 if (parm->flags & SKBMOD_F_SWAPMAC)
130 lflags = SKBMOD_F_SWAPMAC;
131
132 exists = tcf_hash_check(tn, parm->index, a, bind);
133 if (exists && bind)
134 return 0;
135
136 if (!lflags)
137 return -EINVAL;
138
139 if (!exists) {
140 ret = tcf_hash_create(tn, parm->index, est, a,
141 &act_skbmod_ops, bind, true);
142 if (ret)
143 return ret;
144
145 ret = ACT_P_CREATED;
146 } else {
147 tcf_hash_release(*a, bind);
148 if (!ovr)
149 return -EEXIST;
150 }
151
152 d = to_skbmod(*a);
153
154 ASSERT_RTNL();
155 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
156 if (unlikely(!p)) {
157 if (ovr)
158 tcf_hash_release(*a, bind);
159 return -ENOMEM;
160 }
161
162 p->flags = lflags;
163 d->tcf_action = parm->action;
164
165 p_old = rtnl_dereference(d->skbmod_p);
166
167 if (ovr)
168 spin_lock_bh(&d->tcf_lock);
169
170 if (lflags & SKBMOD_F_DMAC)
171 ether_addr_copy(p->eth_dst, daddr);
172 if (lflags & SKBMOD_F_SMAC)
173 ether_addr_copy(p->eth_src, saddr);
174 if (lflags & SKBMOD_F_ETYPE)
175 p->eth_type = htons(eth_type);
176
177 rcu_assign_pointer(d->skbmod_p, p);
178 if (ovr)
179 spin_unlock_bh(&d->tcf_lock);
180
181 if (p_old)
182 kfree_rcu(p_old, rcu);
183
184 if (ret == ACT_P_CREATED)
185 tcf_hash_insert(tn, *a);
186 return ret;
187 }
188
189 static void tcf_skbmod_cleanup(struct tc_action *a, int bind)
190 {
191 struct tcf_skbmod *d = to_skbmod(a);
192 struct tcf_skbmod_params *p;
193
194 p = rcu_dereference_protected(d->skbmod_p, 1);
195 kfree_rcu(p, rcu);
196 }
197
198 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
199 int bind, int ref)
200 {
201 struct tcf_skbmod *d = to_skbmod(a);
202 unsigned char *b = skb_tail_pointer(skb);
203 struct tcf_skbmod_params *p = rtnl_dereference(d->skbmod_p);
204 struct tc_skbmod opt = {
205 .index = d->tcf_index,
206 .refcnt = d->tcf_refcnt - ref,
207 .bindcnt = d->tcf_bindcnt - bind,
208 .action = d->tcf_action,
209 };
210 struct tcf_t t;
211
212 opt.flags = p->flags;
213 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
214 goto nla_put_failure;
215 if ((p->flags & SKBMOD_F_DMAC) &&
216 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
217 goto nla_put_failure;
218 if ((p->flags & SKBMOD_F_SMAC) &&
219 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
220 goto nla_put_failure;
221 if ((p->flags & SKBMOD_F_ETYPE) &&
222 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
223 goto nla_put_failure;
224
225 tcf_tm_dump(&t, &d->tcf_tm);
226 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
227 goto nla_put_failure;
228
229 return skb->len;
230 nla_put_failure:
231 nlmsg_trim(skb, b);
232 return -1;
233 }
234
235 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
236 struct netlink_callback *cb, int type,
237 const struct tc_action_ops *ops)
238 {
239 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
240
241 return tcf_generic_walker(tn, skb, cb, type, ops);
242 }
243
244 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index)
245 {
246 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
247
248 return tcf_hash_search(tn, a, index);
249 }
250
251 static struct tc_action_ops act_skbmod_ops = {
252 .kind = "skbmod",
253 .type = TCA_ACT_SKBMOD,
254 .owner = THIS_MODULE,
255 .act = tcf_skbmod_run,
256 .dump = tcf_skbmod_dump,
257 .init = tcf_skbmod_init,
258 .cleanup = tcf_skbmod_cleanup,
259 .walk = tcf_skbmod_walker,
260 .lookup = tcf_skbmod_search,
261 .size = sizeof(struct tcf_skbmod),
262 };
263
264 static __net_init int skbmod_init_net(struct net *net)
265 {
266 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
267
268 return tc_action_net_init(tn, &act_skbmod_ops, SKBMOD_TAB_MASK);
269 }
270
271 static void __net_exit skbmod_exit_net(struct net *net)
272 {
273 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
274
275 tc_action_net_exit(tn);
276 }
277
278 static struct pernet_operations skbmod_net_ops = {
279 .init = skbmod_init_net,
280 .exit = skbmod_exit_net,
281 .id = &skbmod_net_id,
282 .size = sizeof(struct tc_action_net),
283 };
284
285 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
286 MODULE_DESCRIPTION("SKB data mod-ing");
287 MODULE_LICENSE("GPL");
288
289 static int __init skbmod_init_module(void)
290 {
291 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
292 }
293
294 static void __exit skbmod_cleanup_module(void)
295 {
296 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
297 }
298
299 module_init(skbmod_init_module);
300 module_exit(skbmod_cleanup_module);