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 || !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 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