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. */
buffer_to_cn_msg(__u8 * buffer)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
cn_filter(struct sock * dsk,struct sk_buff * skb,void * data)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 || !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
send_msg(struct cn_msg * msg)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
proc_fork_connector(struct task_struct * task)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
proc_exec_connector(struct task_struct * task)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
proc_id_connector(struct task_struct * task,int which_id)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
proc_sid_connector(struct task_struct * task)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
proc_ptrace_connector(struct task_struct * task,int ptrace_id)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
proc_comm_connector(struct task_struct * task)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
proc_coredump_connector(struct task_struct * task)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
proc_exit_connector(struct task_struct * task)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 */
cn_proc_ack(int err,int rcvd_seq,int rcvd_ack)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 */
cn_proc_mcast_ctl(struct cn_msg * msg,struct netlink_skb_parms * nsp)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 */
cn_proc_init(void)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
