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/netlink.h>
15 #include <net/pkt_sched.h>
16 #include <net/pkt_cls.h>
17
18 #include <linux/tc_act/tc_skbmod.h>
19 #include <net/tc_act/tc_skbmod.h>
20
21 static unsigned int skbmod_net_id;
22 static struct tc_action_ops act_skbmod_ops;
23
24 #define MAX_EDIT_LEN ETH_HLEN
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;
30 struct tcf_skbmod_params *p;
31 u64 flags;
32 int err;
33
34 tcf_lastuse_update(&d->tcf_tm);
35 bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);
36
37 action = READ_ONCE(d->tcf_action);
38 if (unlikely(action == TC_ACT_SHOT))
39 goto drop;
40
41 if (!skb->dev || skb->dev->type != ARPHRD_ETHER)
42 return action;
43
44 /* XXX: if you are going to edit more fields beyond ethernet header
45 * (example when you add IP header replacement or vlan swap)
46 * then MAX_EDIT_LEN needs to change appropriately
47 */
48 err = skb_ensure_writable(skb, MAX_EDIT_LEN);
49 if (unlikely(err)) /* best policy is to drop on the floor */
50 goto drop;
51
52 p = rcu_dereference_bh(d->skbmod_p);
53 flags = p->flags;
54 if (flags & SKBMOD_F_DMAC)
55 ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
56 if (flags & SKBMOD_F_SMAC)
57 ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
58 if (flags & SKBMOD_F_ETYPE)
59 eth_hdr(skb)->h_proto = p->eth_type;
60
61 if (flags & SKBMOD_F_SWAPMAC) {
62 u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
63 /*XXX: I am sure we can come up with more efficient swapping*/
64 ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
65 ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
66 ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
67 }
68
69 return action;
70
71 drop:
72 qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
73 return TC_ACT_SHOT;
74 }
75
76 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
77 [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) },
78 [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN },
79 [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN },
80 [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 },
81 };
82
tcf_skbmod_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,int ovr,int bind,bool rtnl_held,struct tcf_proto * tp,u32 flags,struct netlink_ext_ack * extack)83 static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
84 struct nlattr *est, struct tc_action **a,
85 int ovr, int bind, bool rtnl_held,
86 struct tcf_proto *tp, u32 flags,
87 struct netlink_ext_ack *extack)
88 {
89 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
90 struct nlattr *tb[TCA_SKBMOD_MAX + 1];
91 struct tcf_skbmod_params *p, *p_old;
92 struct tcf_chain *goto_ch = NULL;
93 struct tc_skbmod *parm;
94 u32 lflags = 0, index;
95 struct tcf_skbmod *d;
96 bool exists = false;
97 u8 *daddr = NULL;
98 u8 *saddr = NULL;
99 u16 eth_type = 0;
100 int ret = 0, err;
101
102 if (!nla)
103 return -EINVAL;
104
105 err = nla_parse_nested_deprecated(tb, TCA_SKBMOD_MAX, nla,
106 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 index = parm->index;
130 if (parm->flags & SKBMOD_F_SWAPMAC)
131 lflags = SKBMOD_F_SWAPMAC;
132
133 err = tcf_idr_check_alloc(tn, &index, a, bind);
134 if (err < 0)
135 return err;
136 exists = err;
137 if (exists && bind)
138 return 0;
139
140 if (!lflags) {
141 if (exists)
142 tcf_idr_release(*a, bind);
143 else
144 tcf_idr_cleanup(tn, index);
145 return -EINVAL;
146 }
147
148 if (!exists) {
149 ret = tcf_idr_create(tn, index, est, a,
150 &act_skbmod_ops, bind, true, flags);
151 if (ret) {
152 tcf_idr_cleanup(tn, index);
153 return ret;
154 }
155
156 ret = ACT_P_CREATED;
157 } else if (!ovr) {
158 tcf_idr_release(*a, bind);
159 return -EEXIST;
160 }
161 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
162 if (err < 0)
163 goto release_idr;
164
165 d = to_skbmod(*a);
166
167 p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
168 if (unlikely(!p)) {
169 err = -ENOMEM;
170 goto put_chain;
171 }
172
173 p->flags = lflags;
174
175 if (ovr)
176 spin_lock_bh(&d->tcf_lock);
177 /* Protected by tcf_lock if overwriting existing action. */
178 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
179 p_old = rcu_dereference_protected(d->skbmod_p, 1);
180
181 if (lflags & SKBMOD_F_DMAC)
182 ether_addr_copy(p->eth_dst, daddr);
183 if (lflags & SKBMOD_F_SMAC)
184 ether_addr_copy(p->eth_src, saddr);
185 if (lflags & SKBMOD_F_ETYPE)
186 p->eth_type = htons(eth_type);
187
188 rcu_assign_pointer(d->skbmod_p, p);
189 if (ovr)
190 spin_unlock_bh(&d->tcf_lock);
191
192 if (p_old)
193 kfree_rcu(p_old, rcu);
194 if (goto_ch)
195 tcf_chain_put_by_act(goto_ch);
196
197 return ret;
198 put_chain:
199 if (goto_ch)
200 tcf_chain_put_by_act(goto_ch);
201 release_idr:
202 tcf_idr_release(*a, bind);
203 return err;
204 }
205
tcf_skbmod_cleanup(struct tc_action * a)206 static void tcf_skbmod_cleanup(struct tc_action *a)
207 {
208 struct tcf_skbmod *d = to_skbmod(a);
209 struct tcf_skbmod_params *p;
210
211 p = rcu_dereference_protected(d->skbmod_p, 1);
212 if (p)
213 kfree_rcu(p, rcu);
214 }
215
tcf_skbmod_dump(struct sk_buff * skb,struct tc_action * a,int bind,int ref)216 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
217 int bind, int ref)
218 {
219 struct tcf_skbmod *d = to_skbmod(a);
220 unsigned char *b = skb_tail_pointer(skb);
221 struct tcf_skbmod_params *p;
222 struct tc_skbmod opt = {
223 .index = d->tcf_index,
224 .refcnt = refcount_read(&d->tcf_refcnt) - ref,
225 .bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
226 };
227 struct tcf_t t;
228
229 spin_lock_bh(&d->tcf_lock);
230 opt.action = d->tcf_action;
231 p = rcu_dereference_protected(d->skbmod_p,
232 lockdep_is_held(&d->tcf_lock));
233 opt.flags = p->flags;
234 if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
235 goto nla_put_failure;
236 if ((p->flags & SKBMOD_F_DMAC) &&
237 nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
238 goto nla_put_failure;
239 if ((p->flags & SKBMOD_F_SMAC) &&
240 nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
241 goto nla_put_failure;
242 if ((p->flags & SKBMOD_F_ETYPE) &&
243 nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
244 goto nla_put_failure;
245
246 tcf_tm_dump(&t, &d->tcf_tm);
247 if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
248 goto nla_put_failure;
249
250 spin_unlock_bh(&d->tcf_lock);
251 return skb->len;
252 nla_put_failure:
253 spin_unlock_bh(&d->tcf_lock);
254 nlmsg_trim(skb, b);
255 return -1;
256 }
257
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)258 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
259 struct netlink_callback *cb, int type,
260 const struct tc_action_ops *ops,
261 struct netlink_ext_ack *extack)
262 {
263 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
264
265 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
266 }
267
tcf_skbmod_search(struct net * net,struct tc_action ** a,u32 index)268 static int tcf_skbmod_search(struct net *net, struct tc_action **a, u32 index)
269 {
270 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
271
272 return tcf_idr_search(tn, a, index);
273 }
274
275 static struct tc_action_ops act_skbmod_ops = {
276 .kind = "skbmod",
277 .id = TCA_ACT_SKBMOD,
278 .owner = THIS_MODULE,
279 .act = tcf_skbmod_act,
280 .dump = tcf_skbmod_dump,
281 .init = tcf_skbmod_init,
282 .cleanup = tcf_skbmod_cleanup,
283 .walk = tcf_skbmod_walker,
284 .lookup = tcf_skbmod_search,
285 .size = sizeof(struct tcf_skbmod),
286 };
287
skbmod_init_net(struct net * net)288 static __net_init int skbmod_init_net(struct net *net)
289 {
290 struct tc_action_net *tn = net_generic(net, skbmod_net_id);
291
292 return tc_action_net_init(net, tn, &act_skbmod_ops);
293 }
294
skbmod_exit_net(struct list_head * net_list)295 static void __net_exit skbmod_exit_net(struct list_head *net_list)
296 {
297 tc_action_net_exit(net_list, skbmod_net_id);
298 }
299
300 static struct pernet_operations skbmod_net_ops = {
301 .init = skbmod_init_net,
302 .exit_batch = skbmod_exit_net,
303 .id = &skbmod_net_id,
304 .size = sizeof(struct tc_action_net),
305 };
306
307 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
308 MODULE_DESCRIPTION("SKB data mod-ing");
309 MODULE_LICENSE("GPL");
310
skbmod_init_module(void)311 static int __init skbmod_init_module(void)
312 {
313 return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
314 }
315
skbmod_cleanup_module(void)316 static void __exit skbmod_cleanup_module(void)
317 {
318 tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
319 }
320
321 module_init(skbmod_init_module);
322 module_exit(skbmod_cleanup_module);
323