projects/linux·blob v5.4 · refs

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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/psample/psample.c - Netlink channel for packet sampling
4 * Copyright (c) 2017 Yotam Gigi <[email protected]>
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
20static LIST_HEAD(psample_groups_list);
21static DEFINE_SPINLOCK(psample_groups_lock);
22
23/* multicast groups */
24enum psample_nl_multicast_groups {
25 PSAMPLE_NL_MCGRP_CONFIG,
26 PSAMPLE_NL_MCGRP_SAMPLE,
27};
28
29static 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
34static struct genl_family psample_nl_family __ro_after_init;
35
36static 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
63error:
64 genlmsg_cancel(msg, hdr);
65 return -EMSGSIZE;
66}
67
68static 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_bh(&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_bh(&psample_groups_lock);
93 cb->args[0] = idx;
94 return msg->len;
95}
96
97static const struct genl_ops psample_nl_ops[] = {
98 {
99 .cmd = PSAMPLE_CMD_GET_GROUP,
100 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
101 .dumpit = psample_nl_cmd_get_group_dumpit,
102 /* can be retrieved by unprivileged users */
103 }
104};
105
106static 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
118static 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
136static 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
153static void psample_group_destroy(struct psample_group *group)
154{
155 psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
156 list_del(&group->list);
157 kfree_rcu(group, rcu);
158}
159
160static struct psample_group *
161psample_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
171struct psample_group *psample_group_get(struct net *net, u32 group_num)
172{
173 struct psample_group *group;
174
175 spin_lock_bh(&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
185out:
186 spin_unlock_bh(&psample_groups_lock);
187 return group;
188}
189EXPORT_SYMBOL_GPL(psample_group_get);
190
191void psample_group_take(struct psample_group *group)
192{
193 spin_lock_bh(&psample_groups_lock);
194 group->refcount++;
195 spin_unlock_bh(&psample_groups_lock);
196}
197EXPORT_SYMBOL_GPL(psample_group_take);
198
199void psample_group_put(struct psample_group *group)
200{
201 spin_lock_bh(&psample_groups_lock);
202
203 if (--group->refcount == 0)
204 psample_group_destroy(group);
205
206 spin_unlock_bh(&psample_groups_lock);
207}
208EXPORT_SYMBOL_GPL(psample_group_put);
209
210void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
211 u32 trunc_size, int in_ifindex, int out_ifindex,
212 u32 sample_rate)
213{
214 struct sk_buff *nl_skb;
215 int data_len;
216 int meta_len;
217 void *data;
218 int ret;
219
220 meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
221 (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
222 nla_total_size(sizeof(u32)) + /* sample_rate */
223 nla_total_size(sizeof(u32)) + /* orig_size */
224 nla_total_size(sizeof(u32)) + /* group_num */
225 nla_total_size(sizeof(u32)); /* seq */
226
227 data_len = min(skb->len, trunc_size);
228 if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
229 data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
230 - NLA_ALIGNTO;
231
232 nl_skb = genlmsg_new(meta_len + data_len, GFP_ATOMIC);
233 if (unlikely(!nl_skb))
234 return;
235
236 data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
237 PSAMPLE_CMD_SAMPLE);
238 if (unlikely(!data))
239 goto error;
240
241 if (in_ifindex) {
242 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
243 if (unlikely(ret < 0))
244 goto error;
245 }
246
247 if (out_ifindex) {
248 ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
249 if (unlikely(ret < 0))
250 goto error;
251 }
252
253 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
254 if (unlikely(ret < 0))
255 goto error;
256
257 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
258 if (unlikely(ret < 0))
259 goto error;
260
261 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
262 if (unlikely(ret < 0))
263 goto error;
264
265 ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
266 if (unlikely(ret < 0))
267 goto error;
268
269 if (data_len) {
270 int nla_len = nla_total_size(data_len);
271 struct nlattr *nla;
272
273 nla = skb_put(nl_skb, nla_len);
274 nla->nla_type = PSAMPLE_ATTR_DATA;
275 nla->nla_len = nla_attr_size(data_len);
276
277 if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
278 goto error;
279 }
280
281 genlmsg_end(nl_skb, data);
282 genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
283 PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);
284
285 return;
286error:
287 pr_err_ratelimited("Could not create psample log message\n");
288 nlmsg_free(nl_skb);
289}
290EXPORT_SYMBOL_GPL(psample_sample_packet);
291
292static int __init psample_module_init(void)
293{
294 return genl_register_family(&psample_nl_family);
295}
296
297static void __exit psample_module_exit(void)
298{
299 genl_unregister_family(&psample_nl_family);
300}
301
302module_init(psample_module_init);
303module_exit(psample_module_exit);
304
305MODULE_AUTHOR("Yotam Gigi <[email protected]>");
306MODULE_DESCRIPTION("netlink channel for packet sampling");
307MODULE_LICENSE("GPL v2");