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 <yotamg@mellanox.com>
  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 <yotam.gi@gmail.com>");
306MODULE_DESCRIPTION("netlink channel for packet sampling");
307MODULE_LICENSE("GPL v2");