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
send_msg(struct cn_msg * msg)51 static inline void send_msg(struct cn_msg *msg)
52 {
53 local_lock(&local_event.lock);
54
55 msg->seq = __this_cpu_inc_return(local_event.count) - 1;
56 ((struct proc_event *)msg->data)->cpu = smp_processor_id();
57
58 /*
59 * local_lock() disables preemption during send to ensure the messages
60 * are ordered according to their sequence numbers.
61 *
62 * If cn_netlink_send() fails, the data is not sent.
63 */
64 cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
65
66 local_unlock(&local_event.lock);
67 }
68
proc_fork_connector(struct task_struct * task)69 void proc_fork_connector(struct task_struct *task)
70 {
71 struct cn_msg *msg;
72 struct proc_event *ev;
73 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
74 struct task_struct *parent;
75
76 if (atomic_read(&proc_event_num_listeners) < 1)
77 return;
78
79 msg = buffer_to_cn_msg(buffer);
80 ev = (struct proc_event *)msg->data;
81 memset(&ev->event_data, 0, sizeof(ev->event_data));
82 ev->timestamp_ns = ktime_get_ns();
83 ev->what = PROC_EVENT_FORK;
84 rcu_read_lock();
85 parent = rcu_dereference(task->real_parent);
86 ev->event_data.fork.parent_pid = parent->pid;
87 ev->event_data.fork.parent_tgid = parent->tgid;
88 rcu_read_unlock();
89 ev->event_data.fork.child_pid = task->pid;
90 ev->event_data.fork.child_tgid = task->tgid;
91
92 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
93 msg->ack = 0; /* not used */
94 msg->len = sizeof(*ev);
95 msg->flags = 0; /* not used */
96 send_msg(msg);
97 }
98
proc_exec_connector(struct task_struct * task)99 void proc_exec_connector(struct task_struct *task)
100 {
101 struct cn_msg *msg;
102 struct proc_event *ev;
103 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
104
105 if (atomic_read(&proc_event_num_listeners) < 1)
106 return;
107
108 msg = buffer_to_cn_msg(buffer);
109 ev = (struct proc_event *)msg->data;
110 memset(&ev->event_data, 0, sizeof(ev->event_data));
111 ev->timestamp_ns = ktime_get_ns();
112 ev->what = PROC_EVENT_EXEC;
113 ev->event_data.exec.process_pid = task->pid;
114 ev->event_data.exec.process_tgid = task->tgid;
115
116 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
117 msg->ack = 0; /* not used */
118 msg->len = sizeof(*ev);
119 msg->flags = 0; /* not used */
120 send_msg(msg);
121 }
122
proc_id_connector(struct task_struct * task,int which_id)123 void proc_id_connector(struct task_struct *task, int which_id)
124 {
125 struct cn_msg *msg;
126 struct proc_event *ev;
127 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
128 const struct cred *cred;
129
130 if (atomic_read(&proc_event_num_listeners) < 1)
131 return;
132
133 msg = buffer_to_cn_msg(buffer);
134 ev = (struct proc_event *)msg->data;
135 memset(&ev->event_data, 0, sizeof(ev->event_data));
136 ev->what = which_id;
137 ev->event_data.id.process_pid = task->pid;
138 ev->event_data.id.process_tgid = task->tgid;
139 rcu_read_lock();
140 cred = __task_cred(task);
141 if (which_id == PROC_EVENT_UID) {
142 ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
143 ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
144 } else if (which_id == PROC_EVENT_GID) {
145 ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
146 ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
147 } else {
148 rcu_read_unlock();
149 return;
150 }
151 rcu_read_unlock();
152 ev->timestamp_ns = ktime_get_ns();
153
154 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
155 msg->ack = 0; /* not used */
156 msg->len = sizeof(*ev);
157 msg->flags = 0; /* not used */
158 send_msg(msg);
159 }
160
proc_sid_connector(struct task_struct * task)161 void proc_sid_connector(struct task_struct *task)
162 {
163 struct cn_msg *msg;
164 struct proc_event *ev;
165 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
166
167 if (atomic_read(&proc_event_num_listeners) < 1)
168 return;
169
170 msg = buffer_to_cn_msg(buffer);
171 ev = (struct proc_event *)msg->data;
172 memset(&ev->event_data, 0, sizeof(ev->event_data));
173 ev->timestamp_ns = ktime_get_ns();
174 ev->what = PROC_EVENT_SID;
175 ev->event_data.sid.process_pid = task->pid;
176 ev->event_data.sid.process_tgid = task->tgid;
177
178 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
179 msg->ack = 0; /* not used */
180 msg->len = sizeof(*ev);
181 msg->flags = 0; /* not used */
182 send_msg(msg);
183 }
184
proc_ptrace_connector(struct task_struct * task,int ptrace_id)185 void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
186 {
187 struct cn_msg *msg;
188 struct proc_event *ev;
189 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
190
191 if (atomic_read(&proc_event_num_listeners) < 1)
192 return;
193
194 msg = buffer_to_cn_msg(buffer);
195 ev = (struct proc_event *)msg->data;
196 memset(&ev->event_data, 0, sizeof(ev->event_data));
197 ev->timestamp_ns = ktime_get_ns();
198 ev->what = PROC_EVENT_PTRACE;
199 ev->event_data.ptrace.process_pid = task->pid;
200 ev->event_data.ptrace.process_tgid = task->tgid;
201 if (ptrace_id == PTRACE_ATTACH) {
202 ev->event_data.ptrace.tracer_pid = current->pid;
203 ev->event_data.ptrace.tracer_tgid = current->tgid;
204 } else if (ptrace_id == PTRACE_DETACH) {
205 ev->event_data.ptrace.tracer_pid = 0;
206 ev->event_data.ptrace.tracer_tgid = 0;
207 } else
208 return;
209
210 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
211 msg->ack = 0; /* not used */
212 msg->len = sizeof(*ev);
213 msg->flags = 0; /* not used */
214 send_msg(msg);
215 }
216
proc_comm_connector(struct task_struct * task)217 void proc_comm_connector(struct task_struct *task)
218 {
219 struct cn_msg *msg;
220 struct proc_event *ev;
221 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
222
223 if (atomic_read(&proc_event_num_listeners) < 1)
224 return;
225
226 msg = buffer_to_cn_msg(buffer);
227 ev = (struct proc_event *)msg->data;
228 memset(&ev->event_data, 0, sizeof(ev->event_data));
229 ev->timestamp_ns = ktime_get_ns();
230 ev->what = PROC_EVENT_COMM;
231 ev->event_data.comm.process_pid = task->pid;
232 ev->event_data.comm.process_tgid = task->tgid;
233 get_task_comm(ev->event_data.comm.comm, task);
234
235 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
236 msg->ack = 0; /* not used */
237 msg->len = sizeof(*ev);
238 msg->flags = 0; /* not used */
239 send_msg(msg);
240 }
241
proc_coredump_connector(struct task_struct * task)242 void proc_coredump_connector(struct task_struct *task)
243 {
244 struct cn_msg *msg;
245 struct proc_event *ev;
246 struct task_struct *parent;
247 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
248
249 if (atomic_read(&proc_event_num_listeners) < 1)
250 return;
251
252 msg = buffer_to_cn_msg(buffer);
253 ev = (struct proc_event *)msg->data;
254 memset(&ev->event_data, 0, sizeof(ev->event_data));
255 ev->timestamp_ns = ktime_get_ns();
256 ev->what = PROC_EVENT_COREDUMP;
257 ev->event_data.coredump.process_pid = task->pid;
258 ev->event_data.coredump.process_tgid = task->tgid;
259
260 rcu_read_lock();
261 if (pid_alive(task)) {
262 parent = rcu_dereference(task->real_parent);
263 ev->event_data.coredump.parent_pid = parent->pid;
264 ev->event_data.coredump.parent_tgid = parent->tgid;
265 }
266 rcu_read_unlock();
267
268 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
269 msg->ack = 0; /* not used */
270 msg->len = sizeof(*ev);
271 msg->flags = 0; /* not used */
272 send_msg(msg);
273 }
274
proc_exit_connector(struct task_struct * task)275 void proc_exit_connector(struct task_struct *task)
276 {
277 struct cn_msg *msg;
278 struct proc_event *ev;
279 struct task_struct *parent;
280 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
281
282 if (atomic_read(&proc_event_num_listeners) < 1)
283 return;
284
285 msg = buffer_to_cn_msg(buffer);
286 ev = (struct proc_event *)msg->data;
287 memset(&ev->event_data, 0, sizeof(ev->event_data));
288 ev->timestamp_ns = ktime_get_ns();
289 ev->what = PROC_EVENT_EXIT;
290 ev->event_data.exit.process_pid = task->pid;
291 ev->event_data.exit.process_tgid = task->tgid;
292 ev->event_data.exit.exit_code = task->exit_code;
293 ev->event_data.exit.exit_signal = task->exit_signal;
294
295 rcu_read_lock();
296 if (pid_alive(task)) {
297 parent = rcu_dereference(task->real_parent);
298 ev->event_data.exit.parent_pid = parent->pid;
299 ev->event_data.exit.parent_tgid = parent->tgid;
300 }
301 rcu_read_unlock();
302
303 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
304 msg->ack = 0; /* not used */
305 msg->len = sizeof(*ev);
306 msg->flags = 0; /* not used */
307 send_msg(msg);
308 }
309
310 /*
311 * Send an acknowledgement message to userspace
312 *
313 * Use 0 for success, EFOO otherwise.
314 * Note: this is the negative of conventional kernel error
315 * values because it's not being returned via syscall return
316 * mechanisms.
317 */
cn_proc_ack(int err,int rcvd_seq,int rcvd_ack)318 static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
319 {
320 struct cn_msg *msg;
321 struct proc_event *ev;
322 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
323
324 if (atomic_read(&proc_event_num_listeners) < 1)
325 return;
326
327 msg = buffer_to_cn_msg(buffer);
328 ev = (struct proc_event *)msg->data;
329 memset(&ev->event_data, 0, sizeof(ev->event_data));
330 msg->seq = rcvd_seq;
331 ev->timestamp_ns = ktime_get_ns();
332 ev->cpu = -1;
333 ev->what = PROC_EVENT_NONE;
334 ev->event_data.ack.err = err;
335 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
336 msg->ack = rcvd_ack + 1;
337 msg->len = sizeof(*ev);
338 msg->flags = 0; /* not used */
339 send_msg(msg);
340 }
341
342 /**
343 * cn_proc_mcast_ctl
344 * @data: message sent from userspace via the connector
345 */
cn_proc_mcast_ctl(struct cn_msg * msg,struct netlink_skb_parms * nsp)346 static void cn_proc_mcast_ctl(struct cn_msg *msg,
347 struct netlink_skb_parms *nsp)
348 {
349 enum proc_cn_mcast_op *mc_op = NULL;
350 int err = 0;
351
352 if (msg->len != sizeof(*mc_op))
353 return;
354
355 /*
356 * Events are reported with respect to the initial pid
357 * and user namespaces so ignore requestors from
358 * other namespaces.
359 */
360 if ((current_user_ns() != &init_user_ns) ||
361 !task_is_in_init_pid_ns(current))
362 return;
363
364 /* Can only change if privileged. */
365 if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
366 err = EPERM;
367 goto out;
368 }
369
370 mc_op = (enum proc_cn_mcast_op *)msg->data;
371 switch (*mc_op) {
372 case PROC_CN_MCAST_LISTEN:
373 atomic_inc(&proc_event_num_listeners);
374 break;
375 case PROC_CN_MCAST_IGNORE:
376 atomic_dec(&proc_event_num_listeners);
377 break;
378 default:
379 err = EINVAL;
380 break;
381 }
382
383 out:
384 cn_proc_ack(err, msg->seq, msg->ack);
385 }
386
387 /*
388 * cn_proc_init - initialization entry point
389 *
390 * Adds the connector callback to the connector driver.
391 */
cn_proc_init(void)392 static int __init cn_proc_init(void)
393 {
394 int err = cn_add_callback(&cn_proc_event_id,
395 "cn_proc",
396 &cn_proc_mcast_ctl);
397 if (err) {
398 pr_warn("cn_proc failed to register\n");
399 return err;
400 }
401 return 0;
402 }
403 device_initcall(cn_proc_init);
404