xref: /linux/drivers/connector/cn_proc.c (revision 34dc1baba215b826e454b8d19e4f24adbeb7d00d) 
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. */
33 static 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 
39 static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
40 static 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 */
43 struct local_event {
44 	local_lock_t lock;
45 	__u32 count;
46 };
47 static DEFINE_PER_CPU(struct local_event, local_event) = {
48 	.lock = INIT_LOCAL_LOCK(lock),
49 };
50 
51 static 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 || !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 
88 static 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 
117 void 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 
147 void 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 
171 void 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 
209 void 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 
233 void 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 
265 void 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 
290 void 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 
323 void 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  */
366 static 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  */
395 static 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 
464 out:
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  */
473 static 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 }
484 device_initcall(cn_proc_init);
485