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. */ 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 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 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 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 } 115 116 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 } 153 154 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 } 177 178 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 } 209 210 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 } 234 235 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 } 267 268 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 */ 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 */ 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 */ 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