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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
6ae0a628 YG |
2 | /* |
3 | * net/psample/psample.c - Netlink channel for packet sampling | |
4 | * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com> | |
6ae0a628 YG |
5 | */ |
6 | ||
7 | #include <linux/types.h> | |
8 | #include <linux/kernel.h> | |
9 | #include <linux/skbuff.h> | |
10 | #include <linux/module.h> | |
11 | #include <net/net_namespace.h> | |
12 | #include <net/sock.h> | |
13 | #include <net/netlink.h> | |
14 | #include <net/genetlink.h> | |
15 | #include <net/psample.h> | |
16 | #include <linux/spinlock.h> | |
17 | ||
18 | #define PSAMPLE_MAX_PACKET_SIZE 0xffff | |
19 | ||
20 | static LIST_HEAD(psample_groups_list); | |
21 | static DEFINE_SPINLOCK(psample_groups_lock); | |
22 | ||
23 | /* multicast groups */ | |
24 | enum psample_nl_multicast_groups { | |
25 | PSAMPLE_NL_MCGRP_CONFIG, | |
26 | PSAMPLE_NL_MCGRP_SAMPLE, | |
27 | }; | |
28 | ||
29 | static const struct genl_multicast_group psample_nl_mcgrps[] = { | |
30 | [PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME }, | |
31 | [PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME }, | |
32 | }; | |
33 | ||
34 | static struct genl_family psample_nl_family __ro_after_init; | |
35 | ||
36 | static int psample_group_nl_fill(struct sk_buff *msg, | |
37 | struct psample_group *group, | |
38 | enum psample_command cmd, u32 portid, u32 seq, | |
39 | int flags) | |
40 | { | |
41 | void *hdr; | |
42 | int ret; | |
43 | ||
44 | hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd); | |
45 | if (!hdr) | |
46 | return -EMSGSIZE; | |
47 | ||
48 | ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); | |
49 | if (ret < 0) | |
50 | goto error; | |
51 | ||
52 | ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount); | |
53 | if (ret < 0) | |
54 | goto error; | |
55 | ||
56 | ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq); | |
57 | if (ret < 0) | |
58 | goto error; | |
59 | ||
60 | genlmsg_end(msg, hdr); | |
61 | return 0; | |
62 | ||
63 | error: | |
64 | genlmsg_cancel(msg, hdr); | |
65 | return -EMSGSIZE; | |
66 | } | |
67 | ||
68 | static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg, | |
69 | struct netlink_callback *cb) | |
70 | { | |
71 | struct psample_group *group; | |
72 | int start = cb->args[0]; | |
73 | int idx = 0; | |
74 | int err; | |
75 | ||
76 | spin_lock(&psample_groups_lock); | |
77 | list_for_each_entry(group, &psample_groups_list, list) { | |
78 | if (!net_eq(group->net, sock_net(msg->sk))) | |
79 | continue; | |
80 | if (idx < start) { | |
81 | idx++; | |
82 | continue; | |
83 | } | |
84 | err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP, | |
85 | NETLINK_CB(cb->skb).portid, | |
86 | cb->nlh->nlmsg_seq, NLM_F_MULTI); | |
87 | if (err) | |
88 | break; | |
89 | idx++; | |
90 | } | |
91 | ||
92 | spin_unlock(&psample_groups_lock); | |
93 | cb->args[0] = idx; | |
94 | return msg->len; | |
95 | } | |
96 | ||
97 | static const struct genl_ops psample_nl_ops[] = { | |
98 | { | |
99 | .cmd = PSAMPLE_CMD_GET_GROUP, | |
ef6243ac | 100 | .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, |
6ae0a628 YG |
101 | .dumpit = psample_nl_cmd_get_group_dumpit, |
102 | /* can be retrieved by unprivileged users */ | |
103 | } | |
104 | }; | |
105 | ||
106 | static struct genl_family psample_nl_family __ro_after_init = { | |
107 | .name = PSAMPLE_GENL_NAME, | |
108 | .version = PSAMPLE_GENL_VERSION, | |
109 | .maxattr = PSAMPLE_ATTR_MAX, | |
110 | .netnsok = true, | |
111 | .module = THIS_MODULE, | |
112 | .mcgrps = psample_nl_mcgrps, | |
113 | .ops = psample_nl_ops, | |
114 | .n_ops = ARRAY_SIZE(psample_nl_ops), | |
115 | .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps), | |
116 | }; | |
117 | ||
118 | static void psample_group_notify(struct psample_group *group, | |
119 | enum psample_command cmd) | |
120 | { | |
121 | struct sk_buff *msg; | |
122 | int err; | |
123 | ||
124 | msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); | |
125 | if (!msg) | |
126 | return; | |
127 | ||
128 | err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI); | |
129 | if (!err) | |
130 | genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0, | |
131 | PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC); | |
132 | else | |
133 | nlmsg_free(msg); | |
134 | } | |
135 | ||
136 | static struct psample_group *psample_group_create(struct net *net, | |
137 | u32 group_num) | |
138 | { | |
139 | struct psample_group *group; | |
140 | ||
141 | group = kzalloc(sizeof(*group), GFP_ATOMIC); | |
142 | if (!group) | |
143 | return NULL; | |
144 | ||
145 | group->net = net; | |
146 | group->group_num = group_num; | |
147 | list_add_tail(&group->list, &psample_groups_list); | |
148 | ||
149 | psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP); | |
150 | return group; | |
151 | } | |
152 | ||
153 | static void psample_group_destroy(struct psample_group *group) | |
154 | { | |
155 | psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP); | |
156 | list_del(&group->list); | |
dbf47a2a | 157 | kfree_rcu(group, rcu); |
6ae0a628 YG |
158 | } |
159 | ||
160 | static struct psample_group * | |
161 | psample_group_lookup(struct net *net, u32 group_num) | |
162 | { | |
163 | struct psample_group *group; | |
164 | ||
165 | list_for_each_entry(group, &psample_groups_list, list) | |
166 | if ((group->group_num == group_num) && (group->net == net)) | |
167 | return group; | |
168 | return NULL; | |
169 | } | |
170 | ||
171 | struct psample_group *psample_group_get(struct net *net, u32 group_num) | |
172 | { | |
173 | struct psample_group *group; | |
174 | ||
175 | spin_lock(&psample_groups_lock); | |
176 | ||
177 | group = psample_group_lookup(net, group_num); | |
178 | if (!group) { | |
179 | group = psample_group_create(net, group_num); | |
180 | if (!group) | |
181 | goto out; | |
182 | } | |
183 | group->refcount++; | |
184 | ||
185 | out: | |
186 | spin_unlock(&psample_groups_lock); | |
187 | return group; | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(psample_group_get); | |
190 | ||
191 | void psample_group_put(struct psample_group *group) | |
192 | { | |
193 | spin_lock(&psample_groups_lock); | |
194 | ||
195 | if (--group->refcount == 0) | |
196 | psample_group_destroy(group); | |
197 | ||
198 | spin_unlock(&psample_groups_lock); | |
199 | } | |
200 | EXPORT_SYMBOL_GPL(psample_group_put); | |
201 | ||
202 | void psample_sample_packet(struct psample_group *group, struct sk_buff *skb, | |
203 | u32 trunc_size, int in_ifindex, int out_ifindex, | |
204 | u32 sample_rate) | |
205 | { | |
206 | struct sk_buff *nl_skb; | |
207 | int data_len; | |
208 | int meta_len; | |
209 | void *data; | |
210 | int ret; | |
211 | ||
212 | meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) + | |
213 | (out_ifindex ? nla_total_size(sizeof(u16)) : 0) + | |
214 | nla_total_size(sizeof(u32)) + /* sample_rate */ | |
215 | nla_total_size(sizeof(u32)) + /* orig_size */ | |
216 | nla_total_size(sizeof(u32)) + /* group_num */ | |
217 | nla_total_size(sizeof(u32)); /* seq */ | |
218 | ||
219 | data_len = min(skb->len, trunc_size); | |
220 | if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE) | |
221 | data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN | |
222 | - NLA_ALIGNTO; | |
223 | ||
224 | nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC); | |
225 | if (unlikely(!nl_skb)) | |
226 | return; | |
227 | ||
228 | data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0, | |
229 | PSAMPLE_CMD_SAMPLE); | |
230 | if (unlikely(!data)) | |
231 | goto error; | |
232 | ||
233 | if (in_ifindex) { | |
234 | ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex); | |
235 | if (unlikely(ret < 0)) | |
236 | goto error; | |
237 | } | |
238 | ||
239 | if (out_ifindex) { | |
240 | ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex); | |
241 | if (unlikely(ret < 0)) | |
242 | goto error; | |
243 | } | |
244 | ||
245 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate); | |
246 | if (unlikely(ret < 0)) | |
247 | goto error; | |
248 | ||
249 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len); | |
250 | if (unlikely(ret < 0)) | |
251 | goto error; | |
252 | ||
253 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num); | |
254 | if (unlikely(ret < 0)) | |
255 | goto error; | |
256 | ||
257 | ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++); | |
258 | if (unlikely(ret < 0)) | |
259 | goto error; | |
260 | ||
261 | if (data_len) { | |
262 | int nla_len = nla_total_size(data_len); | |
263 | struct nlattr *nla; | |
264 | ||
4df864c1 | 265 | nla = skb_put(nl_skb, nla_len); |
6ae0a628 YG |
266 | nla->nla_type = PSAMPLE_ATTR_DATA; |
267 | nla->nla_len = nla_attr_size(data_len); | |
268 | ||
269 | if (skb_copy_bits(skb, 0, nla_data(nla), data_len)) | |
270 | goto error; | |
271 | } | |
272 | ||
273 | genlmsg_end(nl_skb, data); | |
274 | genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0, | |
275 | PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC); | |
276 | ||
277 | return; | |
278 | error: | |
279 | pr_err_ratelimited("Could not create psample log message\n"); | |
280 | nlmsg_free(nl_skb); | |
281 | } | |
282 | EXPORT_SYMBOL_GPL(psample_sample_packet); | |
283 | ||
284 | static int __init psample_module_init(void) | |
285 | { | |
286 | return genl_register_family(&psample_nl_family); | |
287 | } | |
288 | ||
289 | static void __exit psample_module_exit(void) | |
290 | { | |
291 | genl_unregister_family(&psample_nl_family); | |
292 | } | |
293 | ||
294 | module_init(psample_module_init); | |
295 | module_exit(psample_module_exit); | |
296 | ||
f1fd20c3 | 297 | MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>"); |
6ae0a628 YG |
298 | MODULE_DESCRIPTION("netlink channel for packet sampling"); |
299 | MODULE_LICENSE("GPL v2"); |