1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * cn_proc.c - process events connector
4 *
5 * Copyright (C) Matt Helsley, IBM Corp. 2005
6 * Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
7 * Original copyright notice follows:
8 * Copyright (C) 2005 BULL SA.
9 */
10
11#include <linux/kernel.h>
12#include <linux/ktime.h>
13#include <linux/init.h>
14#include <linux/connector.h>
15#include <linux/gfp.h>
16#include <linux/ptrace.h>
17#include <linux/atomic.h>
18#include <linux/pid_namespace.h>
19
20#include <linux/cn_proc.h>
21#include <linux/local_lock.h>
22
23/*
24 * Size of a cn_msg followed by a proc_event structure.  Since the
25 * sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
26 * add one 4-byte word to the size here, and then start the actual
27 * cn_msg structure 4 bytes into the stack buffer.  The result is that
28 * the immediately following proc_event structure is aligned to 8 bytes.
29 */
30#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
31
32/* See comment above; we test our assumption about sizeof struct cn_msg here. */
33static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
34{
35	BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
36	return (struct cn_msg *)(buffer + 4);
37}
38
39static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
40static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
41
42/* local_event.count is used as the sequence number of the netlink message */
43struct local_event {
44	local_lock_t lock;
45	__u32 count;
46};
47static DEFINE_PER_CPU(struct local_event, local_event) = {
48	.lock = INIT_LOCAL_LOCK(lock),
49};
50
51static int cn_filter(struct sock *dsk, struct sk_buff *skb, void *data)
52{
53	__u32 what, exit_code, *ptr;
54	enum proc_cn_mcast_op mc_op;
55	uintptr_t val;
56
57	if (!dsk || !dsk->sk_user_data || !data)
58		return 0;
59
60	ptr = (__u32 *)data;
61	what = *ptr++;
62	exit_code = *ptr;
63	val = ((struct proc_input *)(dsk->sk_user_data))->event_type;
64	mc_op = ((struct proc_input *)(dsk->sk_user_data))->mcast_op;
65
66	if (mc_op == PROC_CN_MCAST_IGNORE)
67		return 1;
68
69	if ((__u32)val == PROC_EVENT_ALL)
70		return 0;
71
72	/*
73	 * Drop packet if we have to report only non-zero exit status
74	 * (PROC_EVENT_NONZERO_EXIT) and exit status is 0
75	 */
76	if (((__u32)val & PROC_EVENT_NONZERO_EXIT) &&
77	    (what == PROC_EVENT_EXIT)) {
78		if (exit_code)
79			return 0;
80	}
81
82	if ((__u32)val & what)
83		return 0;
84
85	return 1;
86}
87
88static inline void send_msg(struct cn_msg *msg)
89{
90	__u32 filter_data[2];
91
92	local_lock(&local_event.lock);
93
94	msg->seq = __this_cpu_inc_return(local_event.count) - 1;
95	((struct proc_event *)msg->data)->cpu = smp_processor_id();
96
97	/*
98	 * local_lock() disables preemption during send to ensure the messages
99	 * are ordered according to their sequence numbers.
100	 *
101	 * If cn_netlink_send() fails, the data is not sent.
102	 */
103	filter_data[0] = ((struct proc_event *)msg->data)->what;
104	if (filter_data[0] == PROC_EVENT_EXIT) {
105		filter_data[1] =
106		((struct proc_event *)msg->data)->event_data.exit.exit_code;
107	} else {
108		filter_data[1] = 0;
109	}
110
111	cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
112			     cn_filter, (void *)filter_data);
113
114	local_unlock(&local_event.lock);
115}
116
117void proc_fork_connector(struct task_struct *task)
118{
119	struct cn_msg *msg;
120	struct proc_event *ev;
121	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
122	struct task_struct *parent;
123
124	if (atomic_read(&proc_event_num_listeners) < 1)
125		return;
126
127	msg = buffer_to_cn_msg(buffer);
128	ev = (struct proc_event *)msg->data;
129	memset(&ev->event_data, 0, sizeof(ev->event_data));
130	ev->timestamp_ns = ktime_get_ns();
131	ev->what = PROC_EVENT_FORK;
132	rcu_read_lock();
133	parent = rcu_dereference(task->real_parent);
134	ev->event_data.fork.parent_pid = parent->pid;
135	ev->event_data.fork.parent_tgid = parent->tgid;
136	rcu_read_unlock();
137	ev->event_data.fork.child_pid = task->pid;
138	ev->event_data.fork.child_tgid = task->tgid;
139
140	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
141	msg->ack = 0; /* not used */
142	msg->len = sizeof(*ev);
143	msg->flags = 0; /* not used */
144	send_msg(msg);
145}
146
147void proc_exec_connector(struct task_struct *task)
148{
149	struct cn_msg *msg;
150	struct proc_event *ev;
151	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
152
153	if (atomic_read(&proc_event_num_listeners) < 1)
154		return;
155
156	msg = buffer_to_cn_msg(buffer);
157	ev = (struct proc_event *)msg->data;
158	memset(&ev->event_data, 0, sizeof(ev->event_data));
159	ev->timestamp_ns = ktime_get_ns();
160	ev->what = PROC_EVENT_EXEC;
161	ev->event_data.exec.process_pid = task->pid;
162	ev->event_data.exec.process_tgid = task->tgid;
163
164	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
165	msg->ack = 0; /* not used */
166	msg->len = sizeof(*ev);
167	msg->flags = 0; /* not used */
168	send_msg(msg);
169}
170
171void proc_id_connector(struct task_struct *task, int which_id)
172{
173	struct cn_msg *msg;
174	struct proc_event *ev;
175	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
176	const struct cred *cred;
177
178	if (atomic_read(&proc_event_num_listeners) < 1)
179		return;
180
181	msg = buffer_to_cn_msg(buffer);
182	ev = (struct proc_event *)msg->data;
183	memset(&ev->event_data, 0, sizeof(ev->event_data));
184	ev->what = which_id;
185	ev->event_data.id.process_pid = task->pid;
186	ev->event_data.id.process_tgid = task->tgid;
187	rcu_read_lock();
188	cred = __task_cred(task);
189	if (which_id == PROC_EVENT_UID) {
190		ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
191		ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
192	} else if (which_id == PROC_EVENT_GID) {
193		ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
194		ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
195	} else {
196		rcu_read_unlock();
197		return;
198	}
199	rcu_read_unlock();
200	ev->timestamp_ns = ktime_get_ns();
201
202	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
203	msg->ack = 0; /* not used */
204	msg->len = sizeof(*ev);
205	msg->flags = 0; /* not used */
206	send_msg(msg);
207}
208
209void proc_sid_connector(struct task_struct *task)
210{
211	struct cn_msg *msg;
212	struct proc_event *ev;
213	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
214
215	if (atomic_read(&proc_event_num_listeners) < 1)
216		return;
217
218	msg = buffer_to_cn_msg(buffer);
219	ev = (struct proc_event *)msg->data;
220	memset(&ev->event_data, 0, sizeof(ev->event_data));
221	ev->timestamp_ns = ktime_get_ns();
222	ev->what = PROC_EVENT_SID;
223	ev->event_data.sid.process_pid = task->pid;
224	ev->event_data.sid.process_tgid = task->tgid;
225
226	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
227	msg->ack = 0; /* not used */
228	msg->len = sizeof(*ev);
229	msg->flags = 0; /* not used */
230	send_msg(msg);
231}
232
233void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
234{
235	struct cn_msg *msg;
236	struct proc_event *ev;
237	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
238
239	if (atomic_read(&proc_event_num_listeners) < 1)
240		return;
241
242	msg = buffer_to_cn_msg(buffer);
243	ev = (struct proc_event *)msg->data;
244	memset(&ev->event_data, 0, sizeof(ev->event_data));
245	ev->timestamp_ns = ktime_get_ns();
246	ev->what = PROC_EVENT_PTRACE;
247	ev->event_data.ptrace.process_pid  = task->pid;
248	ev->event_data.ptrace.process_tgid = task->tgid;
249	if (ptrace_id == PTRACE_ATTACH) {
250		ev->event_data.ptrace.tracer_pid  = current->pid;
251		ev->event_data.ptrace.tracer_tgid = current->tgid;
252	} else if (ptrace_id == PTRACE_DETACH) {
253		ev->event_data.ptrace.tracer_pid  = 0;
254		ev->event_data.ptrace.tracer_tgid = 0;
255	} else
256		return;
257
258	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
259	msg->ack = 0; /* not used */
260	msg->len = sizeof(*ev);
261	msg->flags = 0; /* not used */
262	send_msg(msg);
263}
264
265void proc_comm_connector(struct task_struct *task)
266{
267	struct cn_msg *msg;
268	struct proc_event *ev;
269	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
270
271	if (atomic_read(&proc_event_num_listeners) < 1)
272		return;
273
274	msg = buffer_to_cn_msg(buffer);
275	ev = (struct proc_event *)msg->data;
276	memset(&ev->event_data, 0, sizeof(ev->event_data));
277	ev->timestamp_ns = ktime_get_ns();
278	ev->what = PROC_EVENT_COMM;
279	ev->event_data.comm.process_pid  = task->pid;
280	ev->event_data.comm.process_tgid = task->tgid;
281	get_task_comm(ev->event_data.comm.comm, task);
282
283	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
284	msg->ack = 0; /* not used */
285	msg->len = sizeof(*ev);
286	msg->flags = 0; /* not used */
287	send_msg(msg);
288}
289
290void proc_coredump_connector(struct task_struct *task)
291{
292	struct cn_msg *msg;
293	struct proc_event *ev;
294	struct task_struct *parent;
295	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
296
297	if (atomic_read(&proc_event_num_listeners) < 1)
298		return;
299
300	msg = buffer_to_cn_msg(buffer);
301	ev = (struct proc_event *)msg->data;
302	memset(&ev->event_data, 0, sizeof(ev->event_data));
303	ev->timestamp_ns = ktime_get_ns();
304	ev->what = PROC_EVENT_COREDUMP;
305	ev->event_data.coredump.process_pid = task->pid;
306	ev->event_data.coredump.process_tgid = task->tgid;
307
308	rcu_read_lock();
309	if (pid_alive(task)) {
310		parent = rcu_dereference(task->real_parent);
311		ev->event_data.coredump.parent_pid = parent->pid;
312		ev->event_data.coredump.parent_tgid = parent->tgid;
313	}
314	rcu_read_unlock();
315
316	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
317	msg->ack = 0; /* not used */
318	msg->len = sizeof(*ev);
319	msg->flags = 0; /* not used */
320	send_msg(msg);
321}
322
323void proc_exit_connector(struct task_struct *task)
324{
325	struct cn_msg *msg;
326	struct proc_event *ev;
327	struct task_struct *parent;
328	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
329
330	if (atomic_read(&proc_event_num_listeners) < 1)
331		return;
332
333	msg = buffer_to_cn_msg(buffer);
334	ev = (struct proc_event *)msg->data;
335	memset(&ev->event_data, 0, sizeof(ev->event_data));
336	ev->timestamp_ns = ktime_get_ns();
337	ev->what = PROC_EVENT_EXIT;
338	ev->event_data.exit.process_pid = task->pid;
339	ev->event_data.exit.process_tgid = task->tgid;
340	ev->event_data.exit.exit_code = task->exit_code;
341	ev->event_data.exit.exit_signal = task->exit_signal;
342
343	rcu_read_lock();
344	if (pid_alive(task)) {
345		parent = rcu_dereference(task->real_parent);
346		ev->event_data.exit.parent_pid = parent->pid;
347		ev->event_data.exit.parent_tgid = parent->tgid;
348	}
349	rcu_read_unlock();
350
351	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
352	msg->ack = 0; /* not used */
353	msg->len = sizeof(*ev);
354	msg->flags = 0; /* not used */
355	send_msg(msg);
356}
357
358/*
359 * Send an acknowledgement message to userspace
360 *
361 * Use 0 for success, EFOO otherwise.
362 * Note: this is the negative of conventional kernel error
363 * values because it's not being returned via syscall return
364 * mechanisms.
365 */
366static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
367{
368	struct cn_msg *msg;
369	struct proc_event *ev;
370	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
371
372	if (atomic_read(&proc_event_num_listeners) < 1)
373		return;
374
375	msg = buffer_to_cn_msg(buffer);
376	ev = (struct proc_event *)msg->data;
377	memset(&ev->event_data, 0, sizeof(ev->event_data));
378	msg->seq = rcvd_seq;
379	ev->timestamp_ns = ktime_get_ns();
380	ev->cpu = -1;
381	ev->what = PROC_EVENT_NONE;
382	ev->event_data.ack.err = err;
383	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
384	msg->ack = rcvd_ack + 1;
385	msg->len = sizeof(*ev);
386	msg->flags = 0; /* not used */
387	send_msg(msg);
388}
389
390/**
391 * cn_proc_mcast_ctl
392 * @msg: message sent from userspace via the connector
393 * @nsp: NETLINK_CB of the client's socket buffer
394 */
395static void cn_proc_mcast_ctl(struct cn_msg *msg,
396			      struct netlink_skb_parms *nsp)
397{
398	enum proc_cn_mcast_op mc_op = 0, prev_mc_op = 0;
399	struct proc_input *pinput = NULL;
400	enum proc_cn_event ev_type = 0;
401	int err = 0, initial = 0;
402	struct sock *sk = NULL;
403
404	/*
405	 * Events are reported with respect to the initial pid
406	 * and user namespaces so ignore requestors from
407	 * other namespaces.
408	 */
409	if ((current_user_ns() != &init_user_ns) ||
410	    !task_is_in_init_pid_ns(current))
411		return;
412
413	if (msg->len == sizeof(*pinput)) {
414		pinput = (struct proc_input *)msg->data;
415		mc_op = pinput->mcast_op;
416		ev_type = pinput->event_type;
417	} else if (msg->len == sizeof(mc_op)) {
418		mc_op = *((enum proc_cn_mcast_op *)msg->data);
419		ev_type = PROC_EVENT_ALL;
420	} else {
421		return;
422	}
423
424	ev_type = valid_event((enum proc_cn_event)ev_type);
425
426	if (ev_type == PROC_EVENT_NONE)
427		ev_type = PROC_EVENT_ALL;
428
429	if (nsp->sk) {
430		sk = nsp->sk;
431		if (sk->sk_user_data == NULL) {
432			sk->sk_user_data = kzalloc(sizeof(struct proc_input),
433						   GFP_KERNEL);
434			if (sk->sk_user_data == NULL) {
435				err = ENOMEM;
436				goto out;
437			}
438			initial = 1;
439		} else {
440			prev_mc_op =
441			((struct proc_input *)(sk->sk_user_data))->mcast_op;
442		}
443		((struct proc_input *)(sk->sk_user_data))->event_type =
444			ev_type;
445		((struct proc_input *)(sk->sk_user_data))->mcast_op = mc_op;
446	}
447
448	switch (mc_op) {
449	case PROC_CN_MCAST_LISTEN:
450		if (initial || (prev_mc_op != PROC_CN_MCAST_LISTEN))
451			atomic_inc(&proc_event_num_listeners);
452		break;
453	case PROC_CN_MCAST_IGNORE:
454		if (!initial && (prev_mc_op != PROC_CN_MCAST_IGNORE))
455			atomic_dec(&proc_event_num_listeners);
456		((struct proc_input *)(sk->sk_user_data))->event_type =
457			PROC_EVENT_NONE;
458		break;
459	default:
460		err = EINVAL;
461		break;
462	}
463
464out:
465	cn_proc_ack(err, msg->seq, msg->ack);
466}
467
468/*
469 * cn_proc_init - initialization entry point
470 *
471 * Adds the connector callback to the connector driver.
472 */
473static int __init cn_proc_init(void)
474{
475	int err = cn_add_callback(&cn_proc_event_id,
476				  "cn_proc",
477				  &cn_proc_mcast_ctl);
478	if (err) {
479		pr_warn("cn_proc failed to register\n");
480		return err;
481	}
482	return 0;
483}
484device_initcall(cn_proc_init);
485