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86da71b5 JHS |
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 | ||
c7d03a00 | 25 | static unsigned int skbmod_net_id; |
86da71b5 JHS |
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); | |
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: | |
86da71b5 JHS |
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); |