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