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