1// SPDX-License-Identifier: GPL-2.0
  2/* MPTCP socket monitoring support
  3 *
  4 * Copyright (c) 2020 Red Hat
  5 *
  6 * Author: Paolo Abeni <pabeni@redhat.com>
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/net.h>
 11#include <linux/inet_diag.h>
 12#include <net/netlink.h>
 13#include <uapi/linux/mptcp.h>
 14#include "protocol.h"
 15
 16static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
 17			struct netlink_callback *cb,
 18			const struct inet_diag_req_v2 *req,
 19			struct nlattr *bc, bool net_admin)
 20{
 21	if (!inet_diag_bc_sk(bc, sk))
 22		return 0;
 23
 24	return inet_sk_diag_fill(sk, inet_csk(sk), skb, cb, req, NLM_F_MULTI,
 25				 net_admin);
 26}
 27
 28static int mptcp_diag_dump_one(struct netlink_callback *cb,
 29			       const struct inet_diag_req_v2 *req)
 30{
 31	struct sk_buff *in_skb = cb->skb;
 32	struct mptcp_sock *msk = NULL;
 33	struct sk_buff *rep;
 34	int err = -ENOENT;
 35	struct net *net;
 36	struct sock *sk;
 37
 38	net = sock_net(in_skb->sk);
 39	msk = mptcp_token_get_sock(net, req->id.idiag_cookie[0]);
 40	if (!msk)
 41		goto out_nosk;
 42
 43	err = -ENOMEM;
 44	sk = (struct sock *)msk;
 45	rep = nlmsg_new(nla_total_size(sizeof(struct inet_diag_msg)) +
 46			inet_diag_msg_attrs_size() +
 47			nla_total_size(sizeof(struct mptcp_info)) +
 48			nla_total_size(sizeof(struct inet_diag_meminfo)) + 64,
 49			GFP_KERNEL);
 50	if (!rep)
 51		goto out;
 52
 53	err = inet_sk_diag_fill(sk, inet_csk(sk), rep, cb, req, 0,
 54				netlink_net_capable(in_skb, CAP_NET_ADMIN));
 55	if (err < 0) {
 56		WARN_ON(err == -EMSGSIZE);
 57		kfree_skb(rep);
 58		goto out;
 59	}
 60	err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid);
 61
 62out:
 63	sock_put(sk);
 64
 65out_nosk:
 66	return err;
 67}
 68
 69struct mptcp_diag_ctx {
 70	long s_slot;
 71	long s_num;
 72	unsigned int l_slot;
 73	unsigned int l_num;
 74};
 75
 76static void mptcp_diag_dump_listeners(struct sk_buff *skb, struct netlink_callback *cb,
 77				      const struct inet_diag_req_v2 *r,
 78				      bool net_admin)
 79{
 80	struct inet_diag_dump_data *cb_data = cb->data;
 81	struct mptcp_diag_ctx *diag_ctx = (void *)cb->ctx;
 82	struct nlattr *bc = cb_data->inet_diag_nla_bc;
 83	struct net *net = sock_net(skb->sk);
 84	struct inet_hashinfo *hinfo;
 85	int i;
 86
 87	hinfo = net->ipv4.tcp_death_row.hashinfo;
 88
 89	for (i = diag_ctx->l_slot; i <= hinfo->lhash2_mask; i++) {
 90		struct inet_listen_hashbucket *ilb;
 91		struct hlist_nulls_node *node;
 92		struct sock *sk;
 93		int num = 0;
 94
 95		ilb = &hinfo->lhash2[i];
 96
 97		rcu_read_lock();
 98		spin_lock(&ilb->lock);
 99		sk_nulls_for_each(sk, node, &ilb->nulls_head) {
100			const struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk);
101			struct inet_sock *inet = inet_sk(sk);
102			int ret;
103
104			if (num < diag_ctx->l_num)
105				goto next_listen;
106
107			if (!ctx || strcmp(inet_csk(sk)->icsk_ulp_ops->name, "mptcp"))
108				goto next_listen;
109
110			sk = ctx->conn;
111			if (!sk || !net_eq(sock_net(sk), net))
112				goto next_listen;
113
114			if (r->sdiag_family != AF_UNSPEC &&
115			    sk->sk_family != r->sdiag_family)
116				goto next_listen;
117
118			if (r->id.idiag_sport != inet->inet_sport &&
119			    r->id.idiag_sport)
120				goto next_listen;
121
122			if (!refcount_inc_not_zero(&sk->sk_refcnt))
123				goto next_listen;
124
125			ret = sk_diag_dump(sk, skb, cb, r, bc, net_admin);
126
127			sock_put(sk);
128
129			if (ret < 0) {
130				spin_unlock(&ilb->lock);
131				rcu_read_unlock();
132				diag_ctx->l_slot = i;
133				diag_ctx->l_num = num;
134				return;
135			}
136			diag_ctx->l_num = num + 1;
137			num = 0;
138next_listen:
139			++num;
140		}
141		spin_unlock(&ilb->lock);
142		rcu_read_unlock();
143
144		cond_resched();
145		diag_ctx->l_num = 0;
146	}
147
148	diag_ctx->l_num = 0;
149	diag_ctx->l_slot = i;
150}
151
152static void mptcp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
153			    const struct inet_diag_req_v2 *r)
154{
155	bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
156	struct mptcp_diag_ctx *diag_ctx = (void *)cb->ctx;
157	struct net *net = sock_net(skb->sk);
158	struct inet_diag_dump_data *cb_data;
159	struct mptcp_sock *msk;
160	struct nlattr *bc;
161
162	BUILD_BUG_ON(sizeof(cb->ctx) < sizeof(*diag_ctx));
163
164	cb_data = cb->data;
165	bc = cb_data->inet_diag_nla_bc;
166
167	while ((msk = mptcp_token_iter_next(net, &diag_ctx->s_slot,
168					    &diag_ctx->s_num)) != NULL) {
169		struct inet_sock *inet = (struct inet_sock *)msk;
170		struct sock *sk = (struct sock *)msk;
171		int ret = 0;
172
173		if (!(r->idiag_states & (1 << sk->sk_state)))
174			goto next;
175		if (r->sdiag_family != AF_UNSPEC &&
176		    sk->sk_family != r->sdiag_family)
177			goto next;
178		if (r->id.idiag_sport != inet->inet_sport &&
179		    r->id.idiag_sport)
180			goto next;
181		if (r->id.idiag_dport != inet->inet_dport &&
182		    r->id.idiag_dport)
183			goto next;
184
185		ret = sk_diag_dump(sk, skb, cb, r, bc, net_admin);
186next:
187		sock_put(sk);
188		if (ret < 0) {
189			/* will retry on the same position */
190			diag_ctx->s_num--;
191			break;
192		}
193		cond_resched();
194	}
195
196	if ((r->idiag_states & TCPF_LISTEN) && r->id.idiag_dport == 0)
197		mptcp_diag_dump_listeners(skb, cb, r, net_admin);
198}
199
200static void mptcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
201				void *_info)
202{
203	struct mptcp_sock *msk = mptcp_sk(sk);
204	struct mptcp_info *info = _info;
205
206	r->idiag_rqueue = sk_rmem_alloc_get(sk);
207	r->idiag_wqueue = sk_wmem_alloc_get(sk);
208
209	if (inet_sk_state_load(sk) == TCP_LISTEN) {
210		struct sock *lsk = READ_ONCE(msk->first);
211
212		if (lsk) {
213			/* override with settings from tcp listener,
214			 * so Send-Q will show accept queue.
215			 */
216			r->idiag_rqueue = READ_ONCE(lsk->sk_ack_backlog);
217			r->idiag_wqueue = READ_ONCE(lsk->sk_max_ack_backlog);
218		}
219	}
220
221	if (!info)
222		return;
223
224	mptcp_diag_fill_info(msk, info);
225}
226
227static const struct inet_diag_handler mptcp_diag_handler = {
228	.dump		 = mptcp_diag_dump,
229	.dump_one	 = mptcp_diag_dump_one,
230	.idiag_get_info  = mptcp_diag_get_info,
231	.idiag_type	 = IPPROTO_MPTCP,
232	.idiag_info_size = sizeof(struct mptcp_info),
233};
234
235static int __init mptcp_diag_init(void)
236{
237	return inet_diag_register(&mptcp_diag_handler);
238}
239
240static void __exit mptcp_diag_exit(void)
241{
242	inet_diag_unregister(&mptcp_diag_handler);
243}
244
245module_init(mptcp_diag_init);
246module_exit(mptcp_diag_exit);
247MODULE_LICENSE("GPL");
248MODULE_DESCRIPTION("MPTCP socket monitoring via SOCK_DIAG");
249MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-262 /* AF_INET - IPPROTO_MPTCP */);