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6ae0a628 YG |
1 | /* |
2 | * net/psample/psample.c - Netlink channel for packet sampling | |
3 | * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/types.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/skbuff.h> | |
13 | #include <linux/module.h> | |
14 | #include <net/net_namespace.h> | |
15 | #include <net/sock.h> | |
16 | #include <net/netlink.h> | |
17 | #include <net/genetlink.h> | |
18 | #include <net/psample.h> | |
19 | #include <linux/spinlock.h> | |
20 | ||
21 | #define PSAMPLE_MAX_PACKET_SIZE 0xffff | |
22 | ||
23 | static LIST_HEAD(psample_groups_list); | |
24 | static DEFINE_SPINLOCK(psample_groups_lock); | |
25 | ||
26 | /* multicast groups */ | |
27 | enum psample_nl_multicast_groups { | |
28 | PSAMPLE_NL_MCGRP_CONFIG, | |
29 | PSAMPLE_NL_MCGRP_SAMPLE, | |
30 | }; | |
31 | ||
32 | static const struct genl_multicast_group psample_nl_mcgrps[] = { | |
33 | [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME }, | |
34 | [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME }, | |
35 | }; | |
36 | ||
37 | static struct genl_family psample_nl_family __ro_after_init; | |
38 | ||
39 | static int psample_group_nl_fill(struct sk_buff *msg, | |
40 | struct psample_group *group, | |
41 | enum psample_command cmd, u32 portid, u32 seq, | |
42 | int flags) | |
43 | { | |
44 | void *hdr; | |
45 | int ret; | |
46 | ||
47 | hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd); | |
48 | if (!hdr) | |
49 | return -EMSGSIZE; | |
50 | ||
51 | ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); | |
52 | if (ret < 0) | |
53 | goto error; | |
54 | ||
55 | ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount); | |
56 | if (ret < 0) | |
57 | goto error; | |
58 | ||
59 | ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq); | |
60 | if (ret < 0) | |
61 | goto error; | |
62 | ||
63 | genlmsg_end(msg, hdr); | |
64 | return 0; | |
65 | ||
66 | error: | |
67 | genlmsg_cancel(msg, hdr); | |
68 | return -EMSGSIZE; | |
69 | } | |
70 | ||
71 | static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg, | |
72 | struct netlink_callback *cb) | |
73 | { | |
74 | struct psample_group *group; | |
75 | int start = cb->args[0]; | |
76 | int idx = 0; | |
77 | int err; | |
78 | ||
79 | spin_lock(&psample_groups_lock); | |
80 | list_for_each_entry(group, &psample_groups_list, list) { | |
81 | if (!net_eq(group->net, sock_net(msg->sk))) | |
82 | continue; | |
83 | if (idx < start) { | |
84 | idx++; | |
85 | continue; | |
86 | } | |
87 | err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP, | |
88 | NETLINK_CB(cb->skb).portid, | |
89 | cb->nlh->nlmsg_seq, NLM_F_MULTI); | |
90 | if (err) | |
91 | break; | |
92 | idx++; | |
93 | } | |
94 | ||
95 | spin_unlock(&psample_groups_lock); | |
96 | cb->args[0] = idx; | |
97 | return msg->len; | |
98 | } | |
99 | ||
100 | static const struct genl_ops psample_nl_ops[] = { | |
101 | { | |
102 | .cmd = PSAMPLE_CMD_GET_GROUP, | |
103 | .dumpit = psample_nl_cmd_get_group_dumpit, | |
104 | /* can be retrieved by unprivileged users */ | |
105 | } | |
106 | }; | |
107 | ||
108 | static struct genl_family psample_nl_family __ro_after_init = { | |
109 | .name = PSAMPLE_GENL_NAME, | |
110 | .version = PSAMPLE_GENL_VERSION, | |
111 | .maxattr = PSAMPLE_ATTR_MAX, | |
112 | .netnsok = true, | |
113 | .module = THIS_MODULE, | |
114 | .mcgrps = psample_nl_mcgrps, | |
115 | .ops = psample_nl_ops, | |
116 | .n_ops = ARRAY_SIZE(psample_nl_ops), | |
117 | .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), | |
118 | }; | |
119 | ||
120 | static void psample_group_notify(struct psample_group *group, | |
121 | enum psample_command cmd) | |
122 | { | |
123 | struct sk_buff *msg; | |
124 | int err; | |
125 | ||
126 | msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); | |
127 | if (!msg) | |
128 | return; | |
129 | ||
130 | err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); | |
131 | if (!err) | |
132 | genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, | |
133 | PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); | |
134 | else | |
135 | nlmsg_free(msg); | |
136 | } | |
137 | ||
138 | static struct psample_group *psample_group_create(struct net *net, | |
139 | u32 group_num) | |
140 | { | |
141 | struct psample_group *group; | |
142 | ||
143 | group = kzalloc(sizeof(*group), GFP_ATOMIC); | |
144 | if (!group) | |
145 | return NULL; | |
146 | ||
147 | group->net = net; | |
148 | group->group_num = group_num; | |
149 | list_add_tail(&group->list, &psample_groups_list); | |
150 | ||
151 | psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); | |
152 | return group; | |
153 | } | |
154 | ||
155 | static void psample_group_destroy(struct psample_group *group) | |
156 | { | |
157 | psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); | |
158 | list_del(&group->list); | |
159 | kfree(group); | |
160 | } | |
161 | ||
162 | static struct psample_group * | |
163 | psample_group_lookup(struct net *net, u32 group_num) | |
164 | { | |
165 | struct psample_group *group; | |
166 | ||
167 | list_for_each_entry(group, &psample_groups_list, list) | |
168 | if ((group->group_num == group_num) && (group->net == net)) | |
169 | return group; | |
170 | return NULL; | |
171 | } | |
172 | ||
173 | struct psample_group *psample_group_get(struct net *net, u32 group_num) | |
174 | { | |
175 | struct psample_group *group; | |
176 | ||
177 | spin_lock(&psample_groups_lock); | |
178 | ||
179 | group = psample_group_lookup(net, group_num); | |
180 | if (!group) { | |
181 | group = psample_group_create(net, group_num); | |
182 | if (!group) | |
183 | goto out; | |
184 | } | |
185 | group->refcount++; | |
186 | ||
187 | out: | |
188 | spin_unlock(&psample_groups_lock); | |
189 | return group; | |
190 | } | |
191 | EXPORT_SYMBOL_GPL(psample_group_get); | |
192 | ||
193 | void psample_group_put(struct psample_group *group) | |
194 | { | |
195 | spin_lock(&psample_groups_lock); | |
196 | ||
197 | if (--group->refcount == 0) | |
198 | psample_group_destroy(group); | |
199 | ||
200 | spin_unlock(&psample_groups_lock); | |
201 | } | |
202 | EXPORT_SYMBOL_GPL(psample_group_put); | |
203 | ||
204 | void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, | |
205 | u32 trunc_size, int in_ifindex, int out_ifindex, | |
206 | u32 sample_rate) | |
207 | { | |
208 | struct sk_buff *nl_skb; | |
209 | int data_len; | |
210 | int meta_len; | |
211 | void *data; | |
212 | int ret; | |
213 | ||
214 | meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + | |
215 | (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + | |
216 | nla_total_size(sizeof(u32)) + /* sample_rate */ | |
217 | nla_total_size(sizeof(u32)) + /* orig_size */ | |
218 | nla_total_size(sizeof(u32)) + /* group_num */ | |
219 | nla_total_size(sizeof(u32)); /* seq */ | |
220 | ||
221 | data_len = min(skb->len, trunc_size); | |
222 | if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) | |
223 | data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN | |
224 | - NLA_ALIGNTO; | |
225 | ||
226 | nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC); | |
227 | if (unlikely(!nl_skb)) | |
228 | return; | |
229 | ||
230 | data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, | |
231 | PSAMPLE_CMD_SAMPLE); | |
232 | if (unlikely(!data)) | |
233 | goto error; | |
234 | ||
235 | if (in_ifindex) { | |
236 | ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); | |
237 | if (unlikely(ret < 0)) | |
238 | goto error; | |
239 | } | |
240 | ||
241 | if (out_ifindex) { | |
242 | ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); | |
243 | if (unlikely(ret < 0)) | |
244 | goto error; | |
245 | } | |
246 | ||
247 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); | |
248 | if (unlikely(ret < 0)) | |
249 | goto error; | |
250 | ||
251 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); | |
252 | if (unlikely(ret < 0)) | |
253 | goto error; | |
254 | ||
255 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); | |
256 | if (unlikely(ret < 0)) | |
257 | goto error; | |
258 | ||
259 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); | |
260 | if (unlikely(ret < 0)) | |
261 | goto error; | |
262 | ||
263 | if (data_len) { | |
264 | int nla_len = nla_total_size(data_len); | |
265 | struct nlattr *nla; | |
266 | ||
4df864c1 | 267 | nla = skb_put(nl_skb, nla_len); |
6ae0a628 YG |
268 | nla->nla_type = PSAMPLE_ATTR_DATA; |
269 | nla->nla_len = nla_attr_size(data_len); | |
270 | ||
271 | if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) | |
272 | goto error; | |
273 | } | |
274 | ||
275 | genlmsg_end(nl_skb, data); | |
276 | genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, | |
277 | PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); | |
278 | ||
279 | return; | |
280 | error: | |
281 | pr_err_ratelimited("Could not create psample log message\n"); | |
282 | nlmsg_free(nl_skb); | |
283 | } | |
284 | EXPORT_SYMBOL_GPL(psample_sample_packet); | |
285 | ||
286 | static int __init psample_module_init(void) | |
287 | { | |
288 | return genl_register_family(&psample_nl_family); | |
289 | } | |
290 | ||
291 | static void __exit psample_module_exit(void) | |
292 | { | |
293 | genl_unregister_family(&psample_nl_family); | |
294 | } | |
295 | ||
296 | module_init(psample_module_init); | |
297 | module_exit(psample_module_exit); | |
298 | ||
299 | MODULE_AUTHOR("Yotam Gigi <yotamg@mellanox.com>"); | |
300 | MODULE_DESCRIPTION("netlink channel for packet sampling"); | |
301 | MODULE_LICENSE("GPL v2"); |