1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/sched/act_skbmod.c skb data modifier
4 *
5 * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com>
6 */
7
8 #include <linux/module.h>
9 #include <linux/if_arp.h>
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <linux/skbuff.h>
13 #include <linux/rtnetlink.h>
14 #include <net/inet_ecn.h>
15 #include <net/netlink.h>
16 #include <net/pkt_sched.h>
17 #include <net/pkt_cls.h>
18
19 #include <linux/tc_act/tc_skbmod.h>
20 #include <net/tc_act/tc_skbmod.h>
21
22 static unsigned int skbmod_net_id;
23 static struct tc_action_ops act_skbmod_ops;
24
tcf_skbmod_act(struct sk_buff * skb,const struct tc_action * a,struct tcf_result * res)25 static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a,
26 struct tcf_result *res)
27 {
28 struct tcf_skbmod *d = to_skbmod(a);
29 int action, max_edit_len, err;
30 struct tcf_skbmod_params *p;
31 u64 flags;
32
33 tcf_lastuse_update(&d->tcf_tm);
34 bstats_update(this_cpu_ptr(d->common.cpu_bstats), skb);
35
36 action = READ_ONCE(d->tcf_action);
37 if (unlikely(action == TC_ACT_SHOT))
38 goto drop;
39
40 max_edit_len = skb_mac_header_len(skb);
41 p = rcu_dereference_bh(d->skbmod_p);
42 flags = p->flags;
43
44 /* tcf_skbmod_init() guarantees "flags" to be one of the following:
45 * 1. a combination of SKBMOD_F_{DMAC,SMAC,ETYPE}
46 * 2. SKBMOD_F_SWAPMAC
47 * 3. SKBMOD_F_ECN
48 * SKBMOD_F_ECN only works with IP packets; all other flags only work with Ethernet
49 * packets.
50 */
51 if (flags == SKBMOD_F_ECN) {
52 switch (skb_protocol(skb, true)) {
53 case cpu_to_be16(ETH_P_IP):
54 case cpu_to_be16(ETH_P_IPV6):
55 max_edit_len += skb_network_header_len(skb);
56 break;
57 default:
58 goto out;
59 }
60 } else if (!skb->dev || skb->dev->type != ARPHRD_ETHER) {
61 goto out;
62 }
63
64 err = skb_ensure_writable(skb, max_edit_len);
65 if (unlikely(err)) /* best policy is to drop on the floor */
66 goto drop;
67
68 if (flags & SKBMOD_F_DMAC)
69 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
70 if (flags & SKBMOD_F_SMAC)
71 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
72 if (flags & SKBMOD_F_ETYPE)
73 eth_hdr(skb)->h_proto = p->eth_type;
74
75 if (flags & SKBMOD_F_SWAPMAC) {
76 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
77 /*XXX: I am sure we can come up with more efficient swapping*/
78 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
79 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
80 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
81 }
82
83 if (flags & SKBMOD_F_ECN)
84 INET_ECN_set_ce(skb);
85
86 out:
87 return action;
88
89 drop:
90 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
91 return TC_ACT_SHOT;
92 }
93
94 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
95 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) },
96 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN },
97 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN },
98 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 },
99 };
100
tcf_skbmod_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,struct tcf_proto * tp,u32 flags,struct netlink_ext_ack * extack)101 static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
102 struct nlattr *est, struct tc_action **a,
103 struct tcf_proto *tp, u32 flags,
104 struct netlink_ext_ack *extack)
105 {
106 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
107 bool ovr = flags & TCA_ACT_FLAGS_REPLACE;
108 bool bind = flags & TCA_ACT_FLAGS_BIND;
109 struct nlattr *tb[TCA_SKBMOD_MAX + 1];
110 struct tcf_skbmod_params *p, *p_old;
111 struct tcf_chain *goto_ch = NULL;
112 struct tc_skbmod *parm;
113 u32 lflags = 0, index;
114 struct tcf_skbmod *d;
115 bool exists = false;
116 u8 *daddr = NULL;
117 u8 *saddr = NULL;
118 u16 eth_type = 0;
119 int ret = 0, err;
120
121 if (!nla)
122 return -EINVAL;
123
124 err = nla_parse_nested_deprecated(tb, TCA_SKBMOD_MAX, nla,
125 skbmod_policy, NULL);
126 if (err < 0)
127 return err;
128
129 if (!tb[TCA_SKBMOD_PARMS])
130 return -EINVAL;
131
132 if (tb[TCA_SKBMOD_DMAC]) {
133 daddr = nla_data(tb[TCA_SKBMOD_DMAC]);
134 lflags |= SKBMOD_F_DMAC;
135 }
136
137 if (tb[TCA_SKBMOD_SMAC]) {
138 saddr = nla_data(tb[TCA_SKBMOD_SMAC]);
139 lflags |= SKBMOD_F_SMAC;
140 }
141
142 if (tb[TCA_SKBMOD_ETYPE]) {
143 eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]);
144 lflags |= SKBMOD_F_ETYPE;
145 }
146
147 parm = nla_data(tb[TCA_SKBMOD_PARMS]);
148 index = parm->index;
149 if (parm->flags & SKBMOD_F_SWAPMAC)
150 lflags = SKBMOD_F_SWAPMAC;
151 if (parm->flags & SKBMOD_F_ECN)
152 lflags = SKBMOD_F_ECN;
153
154 err = tcf_idr_check_alloc(tn, &index, a, bind);
155 if (err < 0)
156 return err;
157 exists = err;
158 if (exists && bind)
159 return 0;
160
161 if (!lflags) {
162 if (exists)
163 tcf_idr_release(*a, bind);
164 else
165 tcf_idr_cleanup(tn, index);
166 return -EINVAL;
167 }
168
169 if (!exists) {
170 ret = tcf_idr_create(tn, index, est, a,
171 &act_skbmod_ops, bind, true, 0);
172 if (ret) {
173 tcf_idr_cleanup(tn, index);
174 return ret;
175 }
176
177 ret = ACT_P_CREATED;
178 } else if (!ovr) {
179 tcf_idr_release(*a, bind);
180 return -EEXIST;
181 }
182 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
183 if (err < 0)
184 goto release_idr;
185
186 d = to_skbmod(*a);
187
188 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
189 if (unlikely(!p)) {
190 err = -ENOMEM;
191 goto put_chain;
192 }
193
194 p->flags = lflags;
195
196 if (ovr)
197 spin_lock_bh(&d->tcf_lock);
198 /* Protected by tcf_lock if overwriting existing action. */
199 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
200 p_old = rcu_dereference_protected(d->skbmod_p, 1);
201
202 if (lflags & SKBMOD_F_DMAC)
203 ether_addr_copy(p->eth_dst, daddr);
204 if (lflags & SKBMOD_F_SMAC)
205 ether_addr_copy(p->eth_src, saddr);
206 if (lflags & SKBMOD_F_ETYPE)
207 p->eth_type = htons(eth_type);
208
209 rcu_assign_pointer(d->skbmod_p, p);
210 if (ovr)
211 spin_unlock_bh(&d->tcf_lock);
212
213 if (p_old)
214 kfree_rcu(p_old, rcu);
215 if (goto_ch)
216 tcf_chain_put_by_act(goto_ch);
217
218 return ret;
219 put_chain:
220 if (goto_ch)
221 tcf_chain_put_by_act(goto_ch);
222 release_idr:
223 tcf_idr_release(*a, bind);
224 return err;
225 }
226
tcf_skbmod_cleanup(struct tc_action * a)227 static void tcf_skbmod_cleanup(struct tc_action *a)
228 {
229 struct tcf_skbmod *d = to_skbmod(a);
230 struct tcf_skbmod_params *p;
231
232 p = rcu_dereference_protected(d->skbmod_p, 1);
233 if (p)
234 kfree_rcu(p, rcu);
235 }
236
tcf_skbmod_dump(struct sk_buff * skb,struct tc_action * a,int bind,int ref)237 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
238 int bind, int ref)
239 {
240 struct tcf_skbmod *d = to_skbmod(a);
241 unsigned char *b = skb_tail_pointer(skb);
242 struct tcf_skbmod_params *p;
243 struct tc_skbmod opt = {
244 .index = d->tcf_index,
245 .refcnt = refcount_read(&d->tcf_refcnt) - ref,
246 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
247 };
248 struct tcf_t t;
249
250 spin_lock_bh(&d->tcf_lock);
251 opt.action = d->tcf_action;
252 p = rcu_dereference_protected(d->skbmod_p,
253 lockdep_is_held(&d->tcf_lock));
254 opt.flags = p->flags;
255 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
256 goto nla_put_failure;
257 if ((p->flags & SKBMOD_F_DMAC) &&
258 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
259 goto nla_put_failure;
260 if ((p->flags & SKBMOD_F_SMAC) &&
261 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
262 goto nla_put_failure;
263 if ((p->flags & SKBMOD_F_ETYPE) &&
264 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
265 goto nla_put_failure;
266
267 tcf_tm_dump(&t, &d->tcf_tm);
268 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
269 goto nla_put_failure;
270
271 spin_unlock_bh(&d->tcf_lock);
272 return skb->len;
273 nla_put_failure:
274 spin_unlock_bh(&d->tcf_lock);
275 nlmsg_trim(skb, b);
276 return -1;
277 }
278
tcf_skbmod_walker(struct net * net,struct sk_buff * skb,struct netlink_callback * cb,int type,const struct tc_action_ops * ops,struct netlink_ext_ack * extack)279 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
280 struct netlink_callback *cb, int type,
281 const struct tc_action_ops *ops,
282 struct netlink_ext_ack *extack)
283 {
284 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
285
286 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
287 }
288
tcf_skbmod_search(struct net * net,struct tc_action ** a,u32 index)289 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index)
290 {
291 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
292
293 return tcf_idr_search(tn, a, index);
294 }
295
296 static struct tc_action_ops act_skbmod_ops = {
297 .kind = "skbmod",
298 .id = TCA_ACT_SKBMOD,
299 .owner = THIS_MODULE,
300 .act = tcf_skbmod_act,
301 .dump = tcf_skbmod_dump,
302 .init = tcf_skbmod_init,
303 .cleanup = tcf_skbmod_cleanup,
304 .walk = tcf_skbmod_walker,
305 .lookup = tcf_skbmod_search,
306 .size = sizeof(struct tcf_skbmod),
307 };
308
skbmod_init_net(struct net * net)309 static __net_init int skbmod_init_net(struct net *net)
310 {
311 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
312
313 return tc_action_net_init(net, tn, &act_skbmod_ops);
314 }
315
skbmod_exit_net(struct list_head * net_list)316 static void __net_exit skbmod_exit_net(struct list_head *net_list)
317 {
318 tc_action_net_exit(net_list, skbmod_net_id);
319 }
320
321 static struct pernet_operations skbmod_net_ops = {
322 .init = skbmod_init_net,
323 .exit_batch = skbmod_exit_net,
324 .id = &skbmod_net_id,
325 .size = sizeof(struct tc_action_net),
326 };
327
328 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
329 MODULE_DESCRIPTION("SKB data mod-ing");
330 MODULE_LICENSE("GPL");
331
skbmod_init_module(void)332 static int __init skbmod_init_module(void)
333 {
334 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
335 }
336
skbmod_cleanup_module(void)337 static void __exit skbmod_cleanup_module(void)
338 {
339 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
340 }
341
342 module_init(skbmod_init_module);
343 module_exit(skbmod_cleanup_module);
344