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
22 /*
23 * Size of a cn_msg followed by a proc_event structure. Since the
24 * sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
25 * add one 4-byte word to the size here, and then start the actual
26 * cn_msg structure 4 bytes into the stack buffer. The result is that
27 * the immediately following proc_event structure is aligned to 8 bytes.
28 */
29 #define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
30
31 /* See comment above; we test our assumption about sizeof struct cn_msg here. */
buffer_to_cn_msg(__u8 * buffer)32 static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
33 {
34 BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
35 return (struct cn_msg *)(buffer + 4);
36 }
37
38 static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
39 static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
40
41 /* proc_event_counts is used as the sequence number of the netlink message */
42 static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
43
send_msg(struct cn_msg * msg)44 static inline void send_msg(struct cn_msg *msg)
45 {
46 preempt_disable();
47
48 msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
49 ((struct proc_event *)msg->data)->cpu = smp_processor_id();
50
51 /*
52 * Preemption remains disabled during send to ensure the messages are
53 * ordered according to their sequence numbers.
54 *
55 * If cn_netlink_send() fails, the data is not sent.
56 */
57 cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
58
59 preempt_enable();
60 }
61
proc_fork_connector(struct task_struct * task)62 void proc_fork_connector(struct task_struct *task)
63 {
64 struct cn_msg *msg;
65 struct proc_event *ev;
66 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
67 struct task_struct *parent;
68
69 if (atomic_read(&proc_event_num_listeners) < 1)
70 return;
71
72 msg = buffer_to_cn_msg(buffer);
73 ev = (struct proc_event *)msg->data;
74 memset(&ev->event_data, 0, sizeof(ev->event_data));
75 ev->timestamp_ns = ktime_get_ns();
76 ev->what = PROC_EVENT_FORK;
77 rcu_read_lock();
78 parent = rcu_dereference(task->real_parent);
79 ev->event_data.fork.parent_pid = parent->pid;
80 ev->event_data.fork.parent_tgid = parent->tgid;
81 rcu_read_unlock();
82 ev->event_data.fork.child_pid = task->pid;
83 ev->event_data.fork.child_tgid = task->tgid;
84
85 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
86 msg->ack = 0; /* not used */
87 msg->len = sizeof(*ev);
88 msg->flags = 0; /* not used */
89 send_msg(msg);
90 }
91
proc_exec_connector(struct task_struct * task)92 void proc_exec_connector(struct task_struct *task)
93 {
94 struct cn_msg *msg;
95 struct proc_event *ev;
96 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
97
98 if (atomic_read(&proc_event_num_listeners) < 1)
99 return;
100
101 msg = buffer_to_cn_msg(buffer);
102 ev = (struct proc_event *)msg->data;
103 memset(&ev->event_data, 0, sizeof(ev->event_data));
104 ev->timestamp_ns = ktime_get_ns();
105 ev->what = PROC_EVENT_EXEC;
106 ev->event_data.exec.process_pid = task->pid;
107 ev->event_data.exec.process_tgid = task->tgid;
108
109 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
110 msg->ack = 0; /* not used */
111 msg->len = sizeof(*ev);
112 msg->flags = 0; /* not used */
113 send_msg(msg);
114 }
115
proc_id_connector(struct task_struct * task,int which_id)116 void proc_id_connector(struct task_struct *task, int which_id)
117 {
118 struct cn_msg *msg;
119 struct proc_event *ev;
120 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
121 const struct cred *cred;
122
123 if (atomic_read(&proc_event_num_listeners) < 1)
124 return;
125
126 msg = buffer_to_cn_msg(buffer);
127 ev = (struct proc_event *)msg->data;
128 memset(&ev->event_data, 0, sizeof(ev->event_data));
129 ev->what = which_id;
130 ev->event_data.id.process_pid = task->pid;
131 ev->event_data.id.process_tgid = task->tgid;
132 rcu_read_lock();
133 cred = __task_cred(task);
134 if (which_id == PROC_EVENT_UID) {
135 ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
136 ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
137 } else if (which_id == PROC_EVENT_GID) {
138 ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
139 ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
140 } else {
141 rcu_read_unlock();
142 return;
143 }
144 rcu_read_unlock();
145 ev->timestamp_ns = ktime_get_ns();
146
147 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
148 msg->ack = 0; /* not used */
149 msg->len = sizeof(*ev);
150 msg->flags = 0; /* not used */
151 send_msg(msg);
152 }
153
proc_sid_connector(struct task_struct * task)154 void proc_sid_connector(struct task_struct *task)
155 {
156 struct cn_msg *msg;
157 struct proc_event *ev;
158 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
159
160 if (atomic_read(&proc_event_num_listeners) < 1)
161 return;
162
163 msg = buffer_to_cn_msg(buffer);
164 ev = (struct proc_event *)msg->data;
165 memset(&ev->event_data, 0, sizeof(ev->event_data));
166 ev->timestamp_ns = ktime_get_ns();
167 ev->what = PROC_EVENT_SID;
168 ev->event_data.sid.process_pid = task->pid;
169 ev->event_data.sid.process_tgid = task->tgid;
170
171 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
172 msg->ack = 0; /* not used */
173 msg->len = sizeof(*ev);
174 msg->flags = 0; /* not used */
175 send_msg(msg);
176 }
177
proc_ptrace_connector(struct task_struct * task,int ptrace_id)178 void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
179 {
180 struct cn_msg *msg;
181 struct proc_event *ev;
182 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
183
184 if (atomic_read(&proc_event_num_listeners) < 1)
185 return;
186
187 msg = buffer_to_cn_msg(buffer);
188 ev = (struct proc_event *)msg->data;
189 memset(&ev->event_data, 0, sizeof(ev->event_data));
190 ev->timestamp_ns = ktime_get_ns();
191 ev->what = PROC_EVENT_PTRACE;
192 ev->event_data.ptrace.process_pid = task->pid;
193 ev->event_data.ptrace.process_tgid = task->tgid;
194 if (ptrace_id == PTRACE_ATTACH) {
195 ev->event_data.ptrace.tracer_pid = current->pid;
196 ev->event_data.ptrace.tracer_tgid = current->tgid;
197 } else if (ptrace_id == PTRACE_DETACH) {
198 ev->event_data.ptrace.tracer_pid = 0;
199 ev->event_data.ptrace.tracer_tgid = 0;
200 } else
201 return;
202
203 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
204 msg->ack = 0; /* not used */
205 msg->len = sizeof(*ev);
206 msg->flags = 0; /* not used */
207 send_msg(msg);
208 }
209
proc_comm_connector(struct task_struct * task)210 void proc_comm_connector(struct task_struct *task)
211 {
212 struct cn_msg *msg;
213 struct proc_event *ev;
214 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
215
216 if (atomic_read(&proc_event_num_listeners) < 1)
217 return;
218
219 msg = buffer_to_cn_msg(buffer);
220 ev = (struct proc_event *)msg->data;
221 memset(&ev->event_data, 0, sizeof(ev->event_data));
222 ev->timestamp_ns = ktime_get_ns();
223 ev->what = PROC_EVENT_COMM;
224 ev->event_data.comm.process_pid = task->pid;
225 ev->event_data.comm.process_tgid = task->tgid;
226 get_task_comm(ev->event_data.comm.comm, task);
227
228 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
229 msg->ack = 0; /* not used */
230 msg->len = sizeof(*ev);
231 msg->flags = 0; /* not used */
232 send_msg(msg);
233 }
234
proc_coredump_connector(struct task_struct * task)235 void proc_coredump_connector(struct task_struct *task)
236 {
237 struct cn_msg *msg;
238 struct proc_event *ev;
239 struct task_struct *parent;
240 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
241
242 if (atomic_read(&proc_event_num_listeners) < 1)
243 return;
244
245 msg = buffer_to_cn_msg(buffer);
246 ev = (struct proc_event *)msg->data;
247 memset(&ev->event_data, 0, sizeof(ev->event_data));
248 ev->timestamp_ns = ktime_get_ns();
249 ev->what = PROC_EVENT_COREDUMP;
250 ev->event_data.coredump.process_pid = task->pid;
251 ev->event_data.coredump.process_tgid = task->tgid;
252
253 rcu_read_lock();
254 if (pid_alive(task)) {
255 parent = rcu_dereference(task->real_parent);
256 ev->event_data.coredump.parent_pid = parent->pid;
257 ev->event_data.coredump.parent_tgid = parent->tgid;
258 }
259 rcu_read_unlock();
260
261 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
262 msg->ack = 0; /* not used */
263 msg->len = sizeof(*ev);
264 msg->flags = 0; /* not used */
265 send_msg(msg);
266 }
267
proc_exit_connector(struct task_struct * task)268 void proc_exit_connector(struct task_struct *task)
269 {
270 struct cn_msg *msg;
271 struct proc_event *ev;
272 struct task_struct *parent;
273 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
274
275 if (atomic_read(&proc_event_num_listeners) < 1)
276 return;
277
278 msg = buffer_to_cn_msg(buffer);
279 ev = (struct proc_event *)msg->data;
280 memset(&ev->event_data, 0, sizeof(ev->event_data));
281 ev->timestamp_ns = ktime_get_ns();
282 ev->what = PROC_EVENT_EXIT;
283 ev->event_data.exit.process_pid = task->pid;
284 ev->event_data.exit.process_tgid = task->tgid;
285 ev->event_data.exit.exit_code = task->exit_code;
286 ev->event_data.exit.exit_signal = task->exit_signal;
287
288 rcu_read_lock();
289 if (pid_alive(task)) {
290 parent = rcu_dereference(task->real_parent);
291 ev->event_data.exit.parent_pid = parent->pid;
292 ev->event_data.exit.parent_tgid = parent->tgid;
293 }
294 rcu_read_unlock();
295
296 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
297 msg->ack = 0; /* not used */
298 msg->len = sizeof(*ev);
299 msg->flags = 0; /* not used */
300 send_msg(msg);
301 }
302
303 /*
304 * Send an acknowledgement message to userspace
305 *
306 * Use 0 for success, EFOO otherwise.
307 * Note: this is the negative of conventional kernel error
308 * values because it's not being returned via syscall return
309 * mechanisms.
310 */
cn_proc_ack(int err,int rcvd_seq,int rcvd_ack)311 static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
312 {
313 struct cn_msg *msg;
314 struct proc_event *ev;
315 __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
316
317 if (atomic_read(&proc_event_num_listeners) < 1)
318 return;
319
320 msg = buffer_to_cn_msg(buffer);
321 ev = (struct proc_event *)msg->data;
322 memset(&ev->event_data, 0, sizeof(ev->event_data));
323 msg->seq = rcvd_seq;
324 ev->timestamp_ns = ktime_get_ns();
325 ev->cpu = -1;
326 ev->what = PROC_EVENT_NONE;
327 ev->event_data.ack.err = err;
328 memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
329 msg->ack = rcvd_ack + 1;
330 msg->len = sizeof(*ev);
331 msg->flags = 0; /* not used */
332 send_msg(msg);
333 }
334
335 /**
336 * cn_proc_mcast_ctl
337 * @data: message sent from userspace via the connector
338 */
cn_proc_mcast_ctl(struct cn_msg * msg,struct netlink_skb_parms * nsp)339 static void cn_proc_mcast_ctl(struct cn_msg *msg,
340 struct netlink_skb_parms *nsp)
341 {
342 enum proc_cn_mcast_op *mc_op = NULL;
343 int err = 0;
344
345 if (msg->len != sizeof(*mc_op))
346 return;
347
348 /*
349 * Events are reported with respect to the initial pid
350 * and user namespaces so ignore requestors from
351 * other namespaces.
352 */
353 if ((current_user_ns() != &init_user_ns) ||
354 (task_active_pid_ns(current) != &init_pid_ns))
355 return;
356
357 /* Can only change if privileged. */
358 if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
359 err = EPERM;
360 goto out;
361 }
362
363 mc_op = (enum proc_cn_mcast_op *)msg->data;
364 switch (*mc_op) {
365 case PROC_CN_MCAST_LISTEN:
366 atomic_inc(&proc_event_num_listeners);
367 break;
368 case PROC_CN_MCAST_IGNORE:
369 atomic_dec(&proc_event_num_listeners);
370 break;
371 default:
372 err = EINVAL;
373 break;
374 }
375
376 out:
377 cn_proc_ack(err, msg->seq, msg->ack);
378 }
379
380 /*
381 * cn_proc_init - initialization entry point
382 *
383 * Adds the connector callback to the connector driver.
384 */
cn_proc_init(void)385 static int __init cn_proc_init(void)
386 {
387 int err = cn_add_callback(&cn_proc_event_id,
388 "cn_proc",
389 &cn_proc_mcast_ctl);
390 if (err) {
391 pr_warn("cn_proc failed to register\n");
392 return err;
393 }
394 return 0;
395 }
396 device_initcall(cn_proc_init);
397