source3/lib/messages_dgm.c

   1 /*
   2  * Unix SMB/CIFS implementation.
   3  * Samba internal messaging functions
   4  * Copyright (C) 2013 by Volker Lendecke
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21 #include "lib/util/data_blob.h"
  22 #include "lib/util/debug.h"
  23 #include "lib/unix_msg/unix_msg.h"
  24 #include "system/filesys.h"
  25 #include "messages.h"
  26 #include "lib/param/param.h"
  27 #include "poll_funcs/poll_funcs_tevent.h"
  28 #include "unix_msg/unix_msg.h"
  29 #include "librpc/gen_ndr/messaging.h"
  30
  31 struct messaging_dgm_context {
  32         struct messaging_context *msg_ctx;
  33         struct poll_funcs *msg_callbacks;
  34         void *tevent_handle;
  35         struct unix_msg_ctx *dgm_ctx;
  36         char *cache_dir;
  37         int lockfile_fd;
  38 };
  39
  40 struct messaging_dgm_hdr {
  41         uint32_t msg_version;
  42         enum messaging_type msg_type;
  43         struct server_id dst;
  44         struct server_id src;
  45 };
  46
  47 static NTSTATUS messaging_dgm_send(struct messaging_context *msg_ctx,
  48                                    struct server_id pid, int msg_type,
  49                                    const struct iovec *iov, int iovlen,
  50                                    struct messaging_backend *backend);
  51 static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
  52                                uint8_t *msg, size_t msg_len,
  53                                void *private_data);
  54
  55 static int messaging_dgm_context_destructor(struct messaging_dgm_context *c);
  56
  57 static int messaging_dgm_lockfile_create(const char *cache_dir, pid_t pid,
  58                                          int *plockfile_fd, uint64_t unique)
  59 {
  60         char buf[PATH_MAX];
  61         char *dir, *to_free;
  62         ssize_t dirlen;
  63         char *lockfile_name;
  64         int lockfile_fd;
  65         struct flock lck = {};
  66         int unique_len, ret;
  67         ssize_t written;
  68         bool ok;
  69
  70         dirlen = full_path_tos(cache_dir, "lck", buf, sizeof(buf),
  71                                &dir, &to_free);
  72         if (dirlen == -1) {
  73                 return ENOMEM;
  74         }
  75
  76         ok = directory_create_or_exist_strict(dir, sec_initial_uid(), 0755);
  77         if (!ok) {
  78                 ret = errno;
  79                 DEBUG(1, ("%s: Could not create lock directory: %s\n",
  80                           __func__, strerror(ret)));
  81                 TALLOC_FREE(to_free);
  82                 return ret;
  83         }
  84
  85         lockfile_name = talloc_asprintf(talloc_tos(), "%s/%u", dir,
  86                                         (unsigned)pid);
  87         TALLOC_FREE(to_free);
  88         if (lockfile_name == NULL) {
  89                 DEBUG(1, ("%s: talloc_asprintf failed\n", __func__));
  90                 return ENOMEM;
  91         }
  92
  93         /* no O_EXCL, existence check is via the fcntl lock */
  94
  95         lockfile_fd = open(lockfile_name, O_NONBLOCK|O_CREAT|O_WRONLY, 0644);
  96         if (lockfile_fd == -1) {
  97                 ret = errno;
  98                 DEBUG(1, ("%s: open failed: %s\n", __func__, strerror(errno)));
  99                 goto fail_free;
 100         }
 101
 102         lck.l_type = F_WRLCK;
 103         lck.l_whence = SEEK_SET;
 104         lck.l_start = 0;
 105         lck.l_len = 0;
 106
 107         ret = fcntl(lockfile_fd, F_SETLK, &lck);
 108         if (ret == -1) {
 109                 ret = errno;
 110                 DEBUG(1, ("%s: fcntl failed: %s\n", __func__, strerror(ret)));
 111                 goto fail_close;
 112         }
 113
 114         unique_len = snprintf(buf, sizeof(buf), "%"PRIu64, unique);
 115
 116         /* shorten a potentially preexisting file */
 117
 118         ret = ftruncate(lockfile_fd, unique_len);
 119         if (ret == -1) {
 120                 ret = errno;
 121                 DEBUG(1, ("%s: ftruncate failed: %s\n", __func__,
 122                           strerror(ret)));
 123                 goto fail_unlink;
 124         }
 125
 126         written = write(lockfile_fd, buf, unique_len);
 127         if (written != unique_len) {
 128                 ret = errno;
 129                 DEBUG(1, ("%s: write failed: %s\n", __func__, strerror(ret)));
 130                 goto fail_unlink;
 131         }
 132
 133         *plockfile_fd = lockfile_fd;
 134         return 0;
 135
 136 fail_unlink:
 137         unlink(lockfile_name);
 138 fail_close:
 139         close(lockfile_fd);
 140 fail_free:
 141         TALLOC_FREE(lockfile_name);
 142         return ret;
 143 }
 144
 145 static int messaging_dgm_lockfile_remove(const char *cache_dir, pid_t pid)
 146 {
 147         fstring fname;
 148         char buf[PATH_MAX];
 149         char *lockfile_name, *to_free;
 150         ssize_t len;
 151         int ret;
 152
 153         fstr_sprintf(fname, "lck/%u", (unsigned)pid);
 154
 155         len = full_path_tos(cache_dir, fname, buf, sizeof(buf),
 156                             &lockfile_name, &to_free);
 157         if (len == -1) {
 158                 return ENOMEM;
 159         }
 160
 161         ret = unlink(lockfile_name);
 162         if (ret == -1) {
 163                 ret = errno;
 164                 DEBUG(10, ("%s: unlink failed: %s\n", __func__,
 165                            strerror(ret)));
 166         }
 167         TALLOC_FREE(to_free);
 168         return ret;
 169 }
 170
 171 NTSTATUS messaging_dgm_init(struct messaging_context *msg_ctx,
 172                             TALLOC_CTX *mem_ctx,
 173                             struct messaging_backend **presult)
 174 {
 175         struct messaging_backend *result;
 176         struct messaging_dgm_context *ctx;
 177         struct server_id pid = messaging_server_id(msg_ctx);
 178         int ret;
 179         bool ok;
 180         const char *cache_dir;
 181         char *socket_dir, *socket_name;
 182         uint64_t cookie;
 183
 184         cache_dir = lp_cache_directory();
 185         if (cache_dir == NULL) {
 186                 NTSTATUS status = map_nt_error_from_unix(errno);
 187                 return status;
 188         }
 189
 190         result = talloc(mem_ctx, struct messaging_backend);
 191         if (result == NULL) {
 192                 goto fail_nomem;
 193         }
 194         ctx = talloc_zero(result, struct messaging_dgm_context);
 195         if (ctx == NULL) {
 196                 goto fail_nomem;
 197         }
 198
 199         result->private_data = ctx;
 200         result->send_fn = messaging_dgm_send;
 201         ctx->msg_ctx = msg_ctx;
 202
 203         ctx->cache_dir = talloc_strdup(ctx, cache_dir);
 204         if (ctx->cache_dir == NULL) {
 205                 goto fail_nomem;
 206         }
 207         socket_dir = talloc_asprintf(ctx, "%s/msg", cache_dir);
 208         if (socket_dir == NULL) {
 209                 goto fail_nomem;
 210         }
 211         socket_name = talloc_asprintf(ctx, "%s/%u", socket_dir,
 212                                       (unsigned)pid.pid);
 213         if (socket_name == NULL) {
 214                 goto fail_nomem;
 215         }
 216
 217         sec_init();
 218
 219         ret = messaging_dgm_lockfile_create(cache_dir, pid.pid,
 220                                             &ctx->lockfile_fd, pid.unique_id);
 221         if (ret != 0) {
 222                 DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
 223                           __func__, strerror(ret)));
 224                 TALLOC_FREE(result);
 225                 return map_nt_error_from_unix(ret);
 226         }
 227
 228         ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
 229         if (ctx->msg_callbacks == NULL) {
 230                 TALLOC_FREE(result);
 231                 return NT_STATUS_NO_MEMORY;
 232         }
 233
 234         ctx->tevent_handle = poll_funcs_tevent_register(
 235                 ctx, ctx->msg_callbacks, msg_ctx->event_ctx);
 236         if (ctx->tevent_handle == NULL) {
 237                 TALLOC_FREE(result);
 238                 return NT_STATUS_NO_MEMORY;
 239         }
 240
 241         ok = directory_create_or_exist_strict(socket_dir, sec_initial_uid(),
 242                                               0700);
 243         if (!ok) {
 244                 DEBUG(1, ("Could not create socket directory\n"));
 245                 TALLOC_FREE(result);
 246                 return NT_STATUS_ACCESS_DENIED;
 247         }
 248         TALLOC_FREE(socket_dir);
 249
 250         unlink(socket_name);
 251
 252         generate_random_buffer((uint8_t *)&cookie, sizeof(cookie));
 253
 254         ret = unix_msg_init(socket_name, ctx->msg_callbacks, 1024, cookie,
 255                             messaging_dgm_recv, ctx, &ctx->dgm_ctx);
 256         TALLOC_FREE(socket_name);
 257         if (ret != 0) {
 258                 DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
 259                 TALLOC_FREE(result);
 260                 return map_nt_error_from_unix(ret);
 261         }
 262         talloc_set_destructor(ctx, messaging_dgm_context_destructor);
 263
 264         *presult = result;
 265         return NT_STATUS_OK;
 266
 267 fail_nomem:
 268         TALLOC_FREE(result);
 269         return NT_STATUS_NO_MEMORY;
 270 }
 271
 272 static int messaging_dgm_context_destructor(struct messaging_dgm_context *c)
 273 {
 274         struct server_id pid = messaging_server_id(c->msg_ctx);
 275
 276         /*
 277          * First delete the socket to avoid races. The lockfile is the
 278          * indicator that we're still around.
 279          */
 280         unix_msg_free(c->dgm_ctx);
 281
 282         if (getpid() == pid.pid) {
 283                 (void)messaging_dgm_lockfile_remove(c->cache_dir, pid.pid);
 284         }
 285         close(c->lockfile_fd);
 286         return 0;
 287 }
 288
 289 static NTSTATUS messaging_dgm_send(struct messaging_context *msg_ctx,
 290                                    struct server_id pid, int msg_type,
 291                                    const struct iovec *iov, int iovlen,
 292                                    struct messaging_backend *backend)
 293 {
 294         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 295                 backend->private_data, struct messaging_dgm_context);
 296         fstring pid_str;
 297         char buf[PATH_MAX];
 298         char *dst_sock, *to_free;
 299         struct messaging_dgm_hdr hdr;
 300         struct iovec iov2[iovlen + 1];
 301         ssize_t pathlen;
 302         int ret;
 303
 304         fstr_sprintf(pid_str, "msg/%u", (unsigned)pid.pid);
 305
 306         pathlen = full_path_tos(ctx->cache_dir, pid_str, buf, sizeof(buf),
 307                                 &dst_sock, &to_free);
 308         if (pathlen == -1) {
 309                 return NT_STATUS_NO_MEMORY;
 310         }
 311
 312         hdr.msg_version = MESSAGE_VERSION;
 313         hdr.msg_type = msg_type & MSG_TYPE_MASK;
 314         hdr.dst = pid;
 315         hdr.src = msg_ctx->id;
 316
 317         DEBUG(10, ("%s: Sending message 0x%x to %s\n", __func__,
 318                    (unsigned)hdr.msg_type,
 319                    server_id_str(talloc_tos(), &pid)));
 320
 321         iov2[0].iov_base = &hdr;
 322         iov2[0].iov_len = sizeof(hdr);
 323         memcpy(iov2+1, iov, iovlen*sizeof(struct iovec));
 324
 325         become_root();
 326         ret = unix_msg_send(ctx->dgm_ctx, dst_sock, iov2, iovlen + 1);
 327         unbecome_root();
 328
 329         TALLOC_FREE(to_free);
 330
 331         if (ret != 0) {
 332                 return map_nt_error_from_unix(ret);
 333         }
 334         return NT_STATUS_OK;
 335 }
 336
 337 static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
 338                                uint8_t *msg, size_t msg_len,
 339                                void *private_data)
 340 {
 341         struct messaging_dgm_context *dgm_ctx = talloc_get_type_abort(
 342                 private_data, struct messaging_dgm_context);
 343         struct messaging_dgm_hdr *hdr;
 344         struct messaging_rec rec;
 345
 346         if (msg_len < sizeof(*hdr)) {
 347                 DEBUG(1, ("message too short: %u\n", (unsigned)msg_len));
 348                 return;
 349         }
 350
 351         /*
 352          * unix_msg guarantees alignment, so we can cast here
 353          */
 354         hdr = (struct messaging_dgm_hdr *)msg;
 355
 356         rec.msg_version = hdr->msg_version;
 357         rec.msg_type = hdr->msg_type;
 358         rec.dest = hdr->dst;
 359         rec.src = hdr->src;
 360         rec.buf.data = msg + sizeof(*hdr);
 361         rec.buf.length = msg_len - sizeof(*hdr);
 362
 363         DEBUG(10, ("%s: Received message 0x%x len %u from %s\n", __func__,
 364                    (unsigned)hdr->msg_type, (unsigned)rec.buf.length,
 365                    server_id_str(talloc_tos(), &rec.src)));
 366
 367         messaging_dispatch_rec(dgm_ctx->msg_ctx, &rec);
 368 }
 369
 370 NTSTATUS messaging_dgm_cleanup(struct messaging_context *msg_ctx, pid_t pid)
 371 {
 372         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 373                 msg_ctx->local->private_data, struct messaging_dgm_context);
 374         char *lockfile_name, *socket_name;
 375         int fd, ret;
 376         struct flock lck = {};
 377         NTSTATUS status = NT_STATUS_OK;
 378
 379         lockfile_name = talloc_asprintf(talloc_tos(), "%s/lck/%u",
 380                                         ctx->cache_dir, (unsigned)pid);
 381         if (lockfile_name == NULL) {
 382                 return NT_STATUS_NO_MEMORY;
 383         }
 384         socket_name = talloc_asprintf(lockfile_name, "%s/msg/%u",
 385                                       ctx->cache_dir, (unsigned)pid);
 386         if (socket_name == NULL) {
 387                 TALLOC_FREE(lockfile_name);
 388                 return NT_STATUS_NO_MEMORY;
 389         }
 390
 391         fd = open(lockfile_name, O_NONBLOCK|O_WRONLY, 0);
 392         if (fd == -1) {
 393                 status = map_nt_error_from_unix(errno);
 394                 DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
 395                            lockfile_name, strerror(errno)));
 396                 return status;
 397         }
 398
 399         lck.l_type = F_WRLCK;
 400         lck.l_whence = SEEK_SET;
 401         lck.l_start = 0;
 402         lck.l_len = 0;
 403
 404         ret = fcntl(fd, F_SETLK, &lck);
 405         if (ret != 0) {
 406                 status = map_nt_error_from_unix(errno);
 407                 DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
 408                            strerror(errno)));
 409                 TALLOC_FREE(lockfile_name);
 410                 close(fd);
 411                 return status;
 412         }
 413
 414         (void)unlink(socket_name);
 415         (void)unlink(lockfile_name);
 416         (void)close(fd);
 417
 418         TALLOC_FREE(lockfile_name);
 419         return NT_STATUS_OK;
 420 }
 421
 422 NTSTATUS messaging_dgm_wipe(struct messaging_context *msg_ctx)
 423 {
 424         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 425                 msg_ctx->local->private_data, struct messaging_dgm_context);
 426         char *msgdir_name;
 427         DIR *msgdir;
 428         struct dirent *dp;
 429         pid_t our_pid = getpid();
 430
 431         /*
 432          * We scan the socket directory and not the lock directory. Otherwise
 433          * we would race against messaging_dgm_lockfile_create's open(O_CREAT)
 434          * and fcntl(SETLK).
 435          */
 436
 437         msgdir_name = talloc_asprintf(talloc_tos(), "%s/msg", ctx->cache_dir);
 438         if (msgdir_name == NULL) {
 439                 return NT_STATUS_NO_MEMORY;
 440         }
 441
 442         msgdir = opendir(msgdir_name);
 443         TALLOC_FREE(msgdir_name);
 444         if (msgdir == NULL) {
 445                 return map_nt_error_from_unix(errno);
 446         }
 447
 448         while ((dp = readdir(msgdir)) != NULL) {
 449                 NTSTATUS status;
 450                 unsigned long pid;
 451
 452                 pid = strtoul(dp->d_name, NULL, 10);
 453                 if (pid == 0) {
 454                         /*
 455                          * . and .. and other malformed entries
 456                          */
 457                         continue;
 458                 }
 459                 if (pid == our_pid) {
 460                         /*
 461                          * fcntl(F_GETLK) will succeed for ourselves, we hold
 462                          * that lock ourselves.
 463                          */
 464                         continue;
 465                 }
 466
 467                 status = messaging_dgm_cleanup(msg_ctx, pid);
 468                 DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
 469                            pid, nt_errstr(status)));
 470         }
 471         closedir(msgdir);
 472
 473         return NT_STATUS_OK;
 474 }
 475
 476 void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
 477                                             struct messaging_context *msg_ctx,
 478                                             struct tevent_context *ev)
 479 {
 480         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 481                 msg_ctx->local->private_data, struct messaging_dgm_context);
 482         return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
 483 }