drivers/connector/cn_proc.c

   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);