diag.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2
  3#include <linux/dcache.h>
  4#include <linux/module.h>
  5#include <linux/skbuff.h>
  6#include <linux/sock_diag.h>
  7#include <linux/types.h>
  8#include <linux/user_namespace.h>
  9#include <net/af_unix.h>
 10#include <net/netlink.h>
 11#include <net/tcp_states.h>
 12#include <uapi/linux/unix_diag.h>
 13
 14#include "af_unix.h"
 15
 16static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
 17{
 18	/* might or might not have a hash table lock */
 19	struct unix_address *addr = smp_load_acquire(&unix_sk(sk)->addr);
 20
 21	if (!addr)
 22		return 0;
 23
 24	return nla_put(nlskb, UNIX_DIAG_NAME,
 25		       addr->len - offsetof(struct sockaddr_un, sun_path),
 26		       addr->name->sun_path);
 27}
 28
 29static int sk_diag_dump_vfs(struct sock *sk, struct sk_buff *nlskb)
 30{
 31	struct unix_diag_vfs uv;
 32	struct dentry *dentry;
 33	bool have_vfs = false;
 34
 35	unix_state_lock(sk);
 36	dentry = unix_sk(sk)->path.dentry;
 37	if (dentry) {
 38		uv.udiag_vfs_ino = d_backing_inode(dentry)->i_ino;
 39		uv.udiag_vfs_dev = dentry->d_sb->s_dev;
 40		have_vfs = true;
 41	}
 42	unix_state_unlock(sk);
 43
 44	if (!have_vfs)
 45		return 0;
 46
 47	return nla_put(nlskb, UNIX_DIAG_VFS, sizeof(uv), &uv);
 48}
 49
 50static int sk_diag_dump_peer(struct sock *sk, struct sk_buff *nlskb)
 51{
 52	struct sock *peer;
 53	int ino;
 54
 55	peer = unix_peer_get(sk);
 56	if (peer) {
 57		ino = sock_i_ino(peer);
 58		sock_put(peer);
 59
 60		return nla_put_u32(nlskb, UNIX_DIAG_PEER, ino);
 61	}
 62
 63	return 0;
 64}
 65
 66static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
 67{
 68	struct sk_buff *skb;
 69	struct nlattr *attr;
 70	u32 *buf;
 71	int i;
 72
 73	if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
 74		spin_lock(&sk->sk_receive_queue.lock);
 75
 76		attr = nla_reserve(nlskb, UNIX_DIAG_ICONS,
 77				   sk->sk_receive_queue.qlen * sizeof(u32));
 78		if (!attr)
 79			goto errout;
 80
 81		buf = nla_data(attr);
 82		i = 0;
 83		skb_queue_walk(&sk->sk_receive_queue, skb)
 84			buf[i++] = sock_i_ino(unix_peer(skb->sk));
 85
 86		spin_unlock(&sk->sk_receive_queue.lock);
 87	}
 88
 89	return 0;
 90
 91errout:
 92	spin_unlock(&sk->sk_receive_queue.lock);
 93	return -EMSGSIZE;
 94}
 95
 96static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
 97{
 98	struct unix_diag_rqlen rql;
 99
100	if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
101		rql.udiag_rqueue = skb_queue_len_lockless(&sk->sk_receive_queue);
102		rql.udiag_wqueue = sk->sk_max_ack_backlog;
103	} else {
104		rql.udiag_rqueue = (u32) unix_inq_len(sk);
105		rql.udiag_wqueue = (u32) unix_outq_len(sk);
106	}
107
108	return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);
109}
110
111static int sk_diag_dump_uid(struct sock *sk, struct sk_buff *nlskb,
112			    struct user_namespace *user_ns)
113{
114	uid_t uid = from_kuid_munged(user_ns, sk_uid(sk));
115	return nla_put(nlskb, UNIX_DIAG_UID, sizeof(uid_t), &uid);
116}
117
118static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
119			struct user_namespace *user_ns,
120			u32 portid, u32 seq, u32 flags, int sk_ino)
121{
122	struct nlmsghdr *nlh;
123	struct unix_diag_msg *rep;
124
125	nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
126			flags);
127	if (!nlh)
128		return -EMSGSIZE;
129
130	rep = nlmsg_data(nlh);
131	rep->udiag_family = AF_UNIX;
132	rep->udiag_type = sk->sk_type;
133	rep->udiag_state = READ_ONCE(sk->sk_state);
134	rep->pad = 0;
135	rep->udiag_ino = sk_ino;
136	sock_diag_save_cookie(sk, rep->udiag_cookie);
137
138	if ((req->udiag_show & UDIAG_SHOW_NAME) &&
139	    sk_diag_dump_name(sk, skb))
140		goto out_nlmsg_trim;
141
142	if ((req->udiag_show & UDIAG_SHOW_VFS) &&
143	    sk_diag_dump_vfs(sk, skb))
144		goto out_nlmsg_trim;
145
146	if ((req->udiag_show & UDIAG_SHOW_PEER) &&
147	    sk_diag_dump_peer(sk, skb))
148		goto out_nlmsg_trim;
149
150	if ((req->udiag_show & UDIAG_SHOW_ICONS) &&
151	    sk_diag_dump_icons(sk, skb))
152		goto out_nlmsg_trim;
153
154	if ((req->udiag_show & UDIAG_SHOW_RQLEN) &&
155	    sk_diag_show_rqlen(sk, skb))
156		goto out_nlmsg_trim;
157
158	if ((req->udiag_show & UDIAG_SHOW_MEMINFO) &&
159	    sock_diag_put_meminfo(sk, skb, UNIX_DIAG_MEMINFO))
160		goto out_nlmsg_trim;
161
162	if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, READ_ONCE(sk->sk_shutdown)))
163		goto out_nlmsg_trim;
164
165	if ((req->udiag_show & UDIAG_SHOW_UID) &&
166	    sk_diag_dump_uid(sk, skb, user_ns))
167		goto out_nlmsg_trim;
168
169	nlmsg_end(skb, nlh);
170	return 0;
171
172out_nlmsg_trim:
173	nlmsg_cancel(skb, nlh);
174	return -EMSGSIZE;
175}
176
177static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
178{
179	struct net *net = sock_net(skb->sk);
180	int num, s_num, slot, s_slot;
181	struct unix_diag_req *req;
182
183	req = nlmsg_data(cb->nlh);
184
185	s_slot = cb->args[0];
186	num = s_num = cb->args[1];
187
188	for (slot = s_slot; slot < UNIX_HASH_SIZE; s_num = 0, slot++) {
189		struct sock *sk;
190
191		num = 0;
192		spin_lock(&net->unx.table.locks[slot]);
193		sk_for_each(sk, &net->unx.table.buckets[slot]) {
194			int sk_ino;
195
196			if (num < s_num)
197				goto next;
198
199			if (!(req->udiag_states & (1 << READ_ONCE(sk->sk_state))))
200				goto next;
201
202			sk_ino = sock_i_ino(sk);
203			if (!sk_ino)
204				goto next;
205
206			if (sk_diag_fill(sk, skb, req, sk_user_ns(skb->sk),
207					 NETLINK_CB(cb->skb).portid,
208					 cb->nlh->nlmsg_seq,
209					 NLM_F_MULTI, sk_ino) < 0) {
210				spin_unlock(&net->unx.table.locks[slot]);
211				goto done;
212			}
213next:
214			num++;
215		}
216		spin_unlock(&net->unx.table.locks[slot]);
217	}
218done:
219	cb->args[0] = slot;
220	cb->args[1] = num;
221
222	return skb->len;
223}
224
225static struct sock *unix_lookup_by_ino(struct net *net, unsigned int ino)
226{
227	struct sock *sk;
228	int i;
229
230	for (i = 0; i < UNIX_HASH_SIZE; i++) {
231		spin_lock(&net->unx.table.locks[i]);
232		sk_for_each(sk, &net->unx.table.buckets[i]) {
233			if (ino == sock_i_ino(sk)) {
234				sock_hold(sk);
235				spin_unlock(&net->unx.table.locks[i]);
236				return sk;
237			}
238		}
239		spin_unlock(&net->unx.table.locks[i]);
240	}
241	return NULL;
242}
243
244static int unix_diag_get_exact(struct sk_buff *in_skb,
245			       const struct nlmsghdr *nlh,
246			       struct unix_diag_req *req)
247{
248	struct net *net = sock_net(in_skb->sk);
249	unsigned int extra_len;
250	struct sk_buff *rep;
251	struct sock *sk;
252	int err;
253
254	err = -EINVAL;
255	if (req->udiag_ino == 0)
256		goto out_nosk;
257
258	sk = unix_lookup_by_ino(net, req->udiag_ino);
259	err = -ENOENT;
260	if (sk == NULL)
261		goto out_nosk;
262
263	err = sock_diag_check_cookie(sk, req->udiag_cookie);
264	if (err)
265		goto out;
266
267	extra_len = 256;
268again:
269	err = -ENOMEM;
270	rep = nlmsg_new(sizeof(struct unix_diag_msg) + extra_len, GFP_KERNEL);
271	if (!rep)
272		goto out;
273
274	err = sk_diag_fill(sk, rep, req, sk_user_ns(NETLINK_CB(in_skb).sk),
275			   NETLINK_CB(in_skb).portid,
276			   nlh->nlmsg_seq, 0, req->udiag_ino);
277	if (err < 0) {
278		nlmsg_free(rep);
279		extra_len += 256;
280		if (extra_len >= PAGE_SIZE)
281			goto out;
282
283		goto again;
284	}
285	err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid);
286
287out:
288	if (sk)
289		sock_put(sk);
290out_nosk:
291	return err;
292}
293
294static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
295{
296	int hdrlen = sizeof(struct unix_diag_req);
297
298	if (nlmsg_len(h) < hdrlen)
299		return -EINVAL;
300
301	if (h->nlmsg_flags & NLM_F_DUMP) {
302		struct netlink_dump_control c = {
303			.dump = unix_diag_dump,
304		};
305		return netlink_dump_start(sock_net(skb->sk)->diag_nlsk, skb, h, &c);
306	} else
307		return unix_diag_get_exact(skb, h, nlmsg_data(h));
308}
309
310static const struct sock_diag_handler unix_diag_handler = {
311	.owner = THIS_MODULE,
312	.family = AF_UNIX,
313	.dump = unix_diag_handler_dump,
314};
315
316static int __init unix_diag_init(void)
317{
318	return sock_diag_register(&unix_diag_handler);
319}
320
321static void __exit unix_diag_exit(void)
322{
323	sock_diag_unregister(&unix_diag_handler);
324}
325
326module_init(unix_diag_init);
327module_exit(unix_diag_exit);
328MODULE_LICENSE("GPL");
329MODULE_DESCRIPTION("UNIX socket monitoring via SOCK_DIAG");
330MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 1 /* AF_LOCAL */);