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