drivers/connector/cn_proc.c

   1 /*
   2  * cn_proc.c - process events connector
   3  *
   4  * Copyright (C) Matt Helsley, IBM Corp. 2005
   5  * Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
   6  * Original copyright notice follows:
   7  * Copyright (C) 2005 BULL SA.
   8  *
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/kernel.h>
  27 #include <linux/ktime.h>
  28 #include <linux/init.h>
  29 #include <linux/connector.h>
  30 #include <linux/gfp.h>
  31 #include <linux/ptrace.h>
  32 #include <linux/atomic.h>
  33 #include <linux/pid_namespace.h>
  34
  35 #include <linux/cn_proc.h>
  36
  37 /*
  38  * Size of a cn_msg followed by a proc_event structure.  Since the
  39  * sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
  40  * add one 4-byte word to the size here, and then start the actual
  41  * cn_msg structure 4 bytes into the stack buffer.  The result is that
  42  * the immediately following proc_event structure is aligned to 8 bytes.
  43  */
  44 #define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
  45
  46 /* See comment above; we test our assumption about sizeof struct cn_msg here. */
  47 static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
  48 {
  49         BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
  50         return (struct cn_msg *)(buffer + 4);
  51 }
  52
  53 static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
  54 static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
  55
  56 /* proc_event_counts is used as the sequence number of the netlink message */
  57 static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
  58
  59 static inline void send_msg(struct cn_msg *msg)
  60 {
  61         preempt_disable();
  62
  63         msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
  64         ((struct proc_event *)msg->data)->cpu = smp_processor_id();
  65
  66         /*
  67          * Preemption remains disabled during send to ensure the messages are
  68          * ordered according to their sequence numbers.
  69          *
  70          * If cn_netlink_send() fails, the data is not sent.
  71          */
  72         cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
  73
  74         preempt_enable();
  75 }
  76
  77 void proc_fork_connector(struct task_struct *task)
  78 {
  79         struct cn_msg *msg;
  80         struct proc_event *ev;
  81         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
  82         struct task_struct *parent;
  83
  84         if (atomic_read(&proc_event_num_listeners) < 1)
  85                 return;
  86
  87         msg = buffer_to_cn_msg(buffer);
  88         ev = (struct proc_event *)msg->data;
  89         memset(&ev->event_data, 0, sizeof(ev->event_data));
  90         ev->timestamp_ns = ktime_get_ns();
  91         ev->what = PROC_EVENT_FORK;
  92         rcu_read_lock();
  93         parent = rcu_dereference(task->real_parent);
  94         ev->event_data.fork.parent_pid = parent->pid;
  95         ev->event_data.fork.parent_tgid = parent->tgid;
  96         rcu_read_unlock();
  97         ev->event_data.fork.child_pid = task->pid;
  98         ev->event_data.fork.child_tgid = task->tgid;
  99
 100         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 101         msg->ack = 0; /* not used */
 102         msg->len = sizeof(*ev);
 103         msg->flags = 0; /* not used */
 104         send_msg(msg);
 105 }
 106
 107 void proc_exec_connector(struct task_struct *task)
 108 {
 109         struct cn_msg *msg;
 110         struct proc_event *ev;
 111         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 112
 113         if (atomic_read(&proc_event_num_listeners) < 1)
 114                 return;
 115
 116         msg = buffer_to_cn_msg(buffer);
 117         ev = (struct proc_event *)msg->data;
 118         memset(&ev->event_data, 0, sizeof(ev->event_data));
 119         ev->timestamp_ns = ktime_get_ns();
 120         ev->what = PROC_EVENT_EXEC;
 121         ev->event_data.exec.process_pid = task->pid;
 122         ev->event_data.exec.process_tgid = task->tgid;
 123
 124         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 125         msg->ack = 0; /* not used */
 126         msg->len = sizeof(*ev);
 127         msg->flags = 0; /* not used */
 128         send_msg(msg);
 129 }
 130
 131 void proc_id_connector(struct task_struct *task, int which_id)
 132 {
 133         struct cn_msg *msg;
 134         struct proc_event *ev;
 135         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 136         const struct cred *cred;
 137
 138         if (atomic_read(&proc_event_num_listeners) < 1)
 139                 return;
 140
 141         msg = buffer_to_cn_msg(buffer);
 142         ev = (struct proc_event *)msg->data;
 143         memset(&ev->event_data, 0, sizeof(ev->event_data));
 144         ev->what = which_id;
 145         ev->event_data.id.process_pid = task->pid;
 146         ev->event_data.id.process_tgid = task->tgid;
 147         rcu_read_lock();
 148         cred = __task_cred(task);
 149         if (which_id == PROC_EVENT_UID) {
 150                 ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
 151                 ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
 152         } else if (which_id == PROC_EVENT_GID) {
 153                 ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
 154                 ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
 155         } else {
 156                 rcu_read_unlock();
 157                 return;
 158         }
 159         rcu_read_unlock();
 160         ev->timestamp_ns = ktime_get_ns();
 161
 162         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 163         msg->ack = 0; /* not used */
 164         msg->len = sizeof(*ev);
 165         msg->flags = 0; /* not used */
 166         send_msg(msg);
 167 }
 168
 169 void proc_sid_connector(struct task_struct *task)
 170 {
 171         struct cn_msg *msg;
 172         struct proc_event *ev;
 173         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 174
 175         if (atomic_read(&proc_event_num_listeners) < 1)
 176                 return;
 177
 178         msg = buffer_to_cn_msg(buffer);
 179         ev = (struct proc_event *)msg->data;
 180         memset(&ev->event_data, 0, sizeof(ev->event_data));
 181         ev->timestamp_ns = ktime_get_ns();
 182         ev->what = PROC_EVENT_SID;
 183         ev->event_data.sid.process_pid = task->pid;
 184         ev->event_data.sid.process_tgid = task->tgid;
 185
 186         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 187         msg->ack = 0; /* not used */
 188         msg->len = sizeof(*ev);
 189         msg->flags = 0; /* not used */
 190         send_msg(msg);
 191 }
 192
 193 void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
 194 {
 195         struct cn_msg *msg;
 196         struct proc_event *ev;
 197         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 198
 199         if (atomic_read(&proc_event_num_listeners) < 1)
 200                 return;
 201
 202         msg = buffer_to_cn_msg(buffer);
 203         ev = (struct proc_event *)msg->data;
 204         memset(&ev->event_data, 0, sizeof(ev->event_data));
 205         ev->timestamp_ns = ktime_get_ns();
 206         ev->what = PROC_EVENT_PTRACE;
 207         ev->event_data.ptrace.process_pid  = task->pid;
 208         ev->event_data.ptrace.process_tgid = task->tgid;
 209         if (ptrace_id == PTRACE_ATTACH) {
 210                 ev->event_data.ptrace.tracer_pid  = current->pid;
 211                 ev->event_data.ptrace.tracer_tgid = current->tgid;
 212         } else if (ptrace_id == PTRACE_DETACH) {
 213                 ev->event_data.ptrace.tracer_pid  = 0;
 214                 ev->event_data.ptrace.tracer_tgid = 0;
 215         } else
 216                 return;
 217
 218         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 219         msg->ack = 0; /* not used */
 220         msg->len = sizeof(*ev);
 221         msg->flags = 0; /* not used */
 222         send_msg(msg);
 223 }
 224
 225 void proc_comm_connector(struct task_struct *task)
 226 {
 227         struct cn_msg *msg;
 228         struct proc_event *ev;
 229         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 230
 231         if (atomic_read(&proc_event_num_listeners) < 1)
 232                 return;
 233
 234         msg = buffer_to_cn_msg(buffer);
 235         ev = (struct proc_event *)msg->data;
 236         memset(&ev->event_data, 0, sizeof(ev->event_data));
 237         ev->timestamp_ns = ktime_get_ns();
 238         ev->what = PROC_EVENT_COMM;
 239         ev->event_data.comm.process_pid  = task->pid;
 240         ev->event_data.comm.process_tgid = task->tgid;
 241         get_task_comm(ev->event_data.comm.comm, task);
 242
 243         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 244         msg->ack = 0; /* not used */
 245         msg->len = sizeof(*ev);
 246         msg->flags = 0; /* not used */
 247         send_msg(msg);
 248 }
 249
 250 void proc_coredump_connector(struct task_struct *task)
 251 {
 252         struct cn_msg *msg;
 253         struct proc_event *ev;
 254         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 255
 256         if (atomic_read(&proc_event_num_listeners) < 1)
 257                 return;
 258
 259         msg = buffer_to_cn_msg(buffer);
 260         ev = (struct proc_event *)msg->data;
 261         memset(&ev->event_data, 0, sizeof(ev->event_data));
 262         ev->timestamp_ns = ktime_get_ns();
 263         ev->what = PROC_EVENT_COREDUMP;
 264         ev->event_data.coredump.process_pid = task->pid;
 265         ev->event_data.coredump.process_tgid = task->tgid;
 266
 267         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 268         msg->ack = 0; /* not used */
 269         msg->len = sizeof(*ev);
 270         msg->flags = 0; /* not used */
 271         send_msg(msg);
 272 }
 273
 274 void proc_exit_connector(struct task_struct *task)
 275 {
 276         struct cn_msg *msg;
 277         struct proc_event *ev;
 278         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 279
 280         if (atomic_read(&proc_event_num_listeners) < 1)
 281                 return;
 282
 283         msg = buffer_to_cn_msg(buffer);
 284         ev = (struct proc_event *)msg->data;
 285         memset(&ev->event_data, 0, sizeof(ev->event_data));
 286         ev->timestamp_ns = ktime_get_ns();
 287         ev->what = PROC_EVENT_EXIT;
 288         ev->event_data.exit.process_pid = task->pid;
 289         ev->event_data.exit.process_tgid = task->tgid;
 290         ev->event_data.exit.exit_code = task->exit_code;
 291         ev->event_data.exit.exit_signal = task->exit_signal;
 292
 293         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 294         msg->ack = 0; /* not used */
 295         msg->len = sizeof(*ev);
 296         msg->flags = 0; /* not used */
 297         send_msg(msg);
 298 }
 299
 300 /*
 301  * Send an acknowledgement message to userspace
 302  *
 303  * Use 0 for success, EFOO otherwise.
 304  * Note: this is the negative of conventional kernel error
 305  * values because it's not being returned via syscall return
 306  * mechanisms.
 307  */
 308 static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
 309 {
 310         struct cn_msg *msg;
 311         struct proc_event *ev;
 312         __u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 313
 314         if (atomic_read(&proc_event_num_listeners) < 1)
 315                 return;
 316
 317         msg = buffer_to_cn_msg(buffer);
 318         ev = (struct proc_event *)msg->data;
 319         memset(&ev->event_data, 0, sizeof(ev->event_data));
 320         msg->seq = rcvd_seq;
 321         ev->timestamp_ns = ktime_get_ns();
 322         ev->cpu = -1;
 323         ev->what = PROC_EVENT_NONE;
 324         ev->event_data.ack.err = err;
 325         memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
 326         msg->ack = rcvd_ack + 1;
 327         msg->len = sizeof(*ev);
 328         msg->flags = 0; /* not used */
 329         send_msg(msg);
 330 }
 331
 332 /**
 333  * cn_proc_mcast_ctl
 334  * @data: message sent from userspace via the connector
 335  */
 336 static void cn_proc_mcast_ctl(struct cn_msg *msg,
 337                               struct netlink_skb_parms *nsp)
 338 {
 339         enum proc_cn_mcast_op *mc_op = NULL;
 340         int err = 0;
 341
 342         if (msg->len != sizeof(*mc_op))
 343                 return;
 344
 345         /*
 346          * Events are reported with respect to the initial pid
 347          * and user namespaces so ignore requestors from
 348          * other namespaces.
 349          */
 350         if ((current_user_ns() != &init_user_ns) ||
 351             (task_active_pid_ns(current) != &init_pid_ns))
 352                 return;
 353
 354         /* Can only change if privileged. */
 355         if (!__netlink_ns_capable(nsp, &init_user_ns, CAP_NET_ADMIN)) {
 356                 err = EPERM;
 357                 goto out;
 358         }
 359
 360         mc_op = (enum proc_cn_mcast_op *)msg->data;
 361         switch (*mc_op) {
 362         case PROC_CN_MCAST_LISTEN:
 363                 atomic_inc(&proc_event_num_listeners);
 364                 break;
 365         case PROC_CN_MCAST_IGNORE:
 366                 atomic_dec(&proc_event_num_listeners);
 367                 break;
 368         default:
 369                 err = EINVAL;
 370                 break;
 371         }
 372
 373 out:
 374         cn_proc_ack(err, msg->seq, msg->ack);
 375 }
 376
 377 /*
 378  * cn_proc_init - initialization entry point
 379  *
 380  * Adds the connector callback to the connector driver.
 381  */
 382 static int __init cn_proc_init(void)
 383 {
 384         int err = cn_add_callback(&cn_proc_event_id,
 385                                   "cn_proc",
 386                                   &cn_proc_mcast_ctl);
 387         if (err) {
 388                 pr_warn("cn_proc failed to register\n");
 389                 return err;
 390         }
 391         return 0;
 392 }
 393
 394 module_init(cn_proc_init);