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
  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);