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 int messaging_dgm_send(struct server_id src,
  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(TALLOC_CTX *tmp_ctx,
  58                                          const char *cache_dir, pid_t pid,
  59                                          int *plockfile_fd, uint64_t unique)
  60 {
  61         fstring buf;
  62         char *dir;
  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         dir = talloc_asprintf(tmp_ctx, "%s/lck", cache_dir);
  71         if (dir == NULL) {
  72                 return ENOMEM;
  73         }
  74
  75         ok = directory_create_or_exist_strict(dir, sec_initial_uid(), 0755);
  76         if (!ok) {
  77                 ret = errno;
  78                 DEBUG(1, ("%s: Could not create lock directory: %s\n",
  79                           __func__, strerror(ret)));
  80                 TALLOC_FREE(dir);
  81                 return ret;
  82         }
  83
  84         lockfile_name = talloc_asprintf(tmp_ctx, "%s/%u", dir,
  85                                         (unsigned)pid);
  86         TALLOC_FREE(dir);
  87         if (lockfile_name == NULL) {
  88                 DEBUG(1, ("%s: talloc_asprintf failed\n", __func__));
  89                 return ENOMEM;
  90         }
  91
  92         /* no O_EXCL, existence check is via the fcntl lock */
  93
  94         lockfile_fd = open(lockfile_name, O_NONBLOCK|O_CREAT|O_WRONLY, 0644);
  95         if (lockfile_fd == -1) {
  96                 ret = errno;
  97                 DEBUG(1, ("%s: open failed: %s\n", __func__, strerror(errno)));
  98                 goto fail_free;
  99         }
 100
 101         lck.l_type = F_WRLCK;
 102         lck.l_whence = SEEK_SET;
 103         lck.l_start = 0;
 104         lck.l_len = 0;
 105
 106         ret = fcntl(lockfile_fd, F_SETLK, &lck);
 107         if (ret == -1) {
 108                 ret = errno;
 109                 DEBUG(1, ("%s: fcntl failed: %s\n", __func__, strerror(ret)));
 110                 goto fail_close;
 111         }
 112
 113         unique_len = snprintf(buf, sizeof(buf), "%"PRIu64, unique);
 114
 115         /* shorten a potentially preexisting file */
 116
 117         ret = ftruncate(lockfile_fd, unique_len);
 118         if (ret == -1) {
 119                 ret = errno;
 120                 DEBUG(1, ("%s: ftruncate failed: %s\n", __func__,
 121                           strerror(ret)));
 122                 goto fail_unlink;
 123         }
 124
 125         written = write(lockfile_fd, buf, unique_len);
 126         if (written != unique_len) {
 127                 ret = errno;
 128                 DEBUG(1, ("%s: write failed: %s\n", __func__, strerror(ret)));
 129                 goto fail_unlink;
 130         }
 131
 132         TALLOC_FREE(lockfile_name);
 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(TALLOC_CTX *tmp_ctx,
 146                                          const char *cache_dir, pid_t pid)
 147 {
 148         char *lockfile_name;
 149         int ret;
 150
 151         lockfile_name = talloc_asprintf(
 152                 tmp_ctx, "%s/lck/%u", cache_dir, (unsigned)pid);
 153         if (lockfile_name == NULL) {
 154                 return ENOMEM;
 155         }
 156
 157         ret = unlink(lockfile_name);
 158         if (ret == -1) {
 159                 ret = errno;
 160                 DEBUG(10, ("%s: unlink(%s) failed: %s\n", __func__,
 161                            lockfile_name, strerror(ret)));
 162         }
 163
 164         TALLOC_FREE(lockfile_name);
 165         return ret;
 166 }
 167
 168 NTSTATUS messaging_dgm_init(struct messaging_context *msg_ctx,
 169                             TALLOC_CTX *mem_ctx,
 170                             struct messaging_backend **presult)
 171 {
 172         struct messaging_backend *result;
 173         struct messaging_dgm_context *ctx;
 174         struct server_id pid = messaging_server_id(msg_ctx);
 175         int ret;
 176         bool ok;
 177         const char *cache_dir;
 178         char *socket_dir;
 179         struct sockaddr_un socket_address;
 180         size_t sockname_len;
 181         uint64_t cookie;
 182
 183         cache_dir = lp_cache_directory();
 184         if (cache_dir == NULL) {
 185                 NTSTATUS status = map_nt_error_from_unix(errno);
 186                 return status;
 187         }
 188
 189         result = talloc(mem_ctx, struct messaging_backend);
 190         if (result == NULL) {
 191                 goto fail_nomem;
 192         }
 193         ctx = talloc_zero(result, struct messaging_dgm_context);
 194         if (ctx == NULL) {
 195                 goto fail_nomem;
 196         }
 197
 198         result->private_data = ctx;
 199         result->send_fn = messaging_dgm_send;
 200         ctx->msg_ctx = msg_ctx;
 201
 202         ctx->cache_dir = talloc_strdup(ctx, cache_dir);
 203         if (ctx->cache_dir == NULL) {
 204                 goto fail_nomem;
 205         }
 206         socket_dir = talloc_asprintf(ctx, "%s/msg", cache_dir);
 207         if (socket_dir == NULL) {
 208                 goto fail_nomem;
 209         }
 210
 211         socket_address = (struct sockaddr_un) { .sun_family = AF_UNIX };
 212         sockname_len = snprintf(socket_address.sun_path,
 213                                 sizeof(socket_address.sun_path),
 214                                 "%s/%u", socket_dir, (unsigned)pid.pid);
 215         if (sockname_len >= sizeof(socket_address.sun_path)) {
 216                 TALLOC_FREE(result);
 217                 return NT_STATUS_NAME_TOO_LONG;
 218         }
 219
 220         sec_init();
 221
 222         ret = messaging_dgm_lockfile_create(ctx, cache_dir, pid.pid,
 223                                             &ctx->lockfile_fd, pid.unique_id);
 224         if (ret != 0) {
 225                 DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
 226                           __func__, strerror(ret)));
 227                 TALLOC_FREE(result);
 228                 return map_nt_error_from_unix(ret);
 229         }
 230
 231         ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
 232         if (ctx->msg_callbacks == NULL) {
 233                 goto fail_nomem;
 234         }
 235
 236         ctx->tevent_handle = poll_funcs_tevent_register(
 237                 ctx, ctx->msg_callbacks,
 238                 messaging_tevent_context(msg_ctx));
 239         if (ctx->tevent_handle == NULL) {
 240                 goto fail_nomem;
 241         }
 242
 243         ok = directory_create_or_exist_strict(socket_dir, sec_initial_uid(),
 244                                               0700);
 245         if (!ok) {
 246                 DEBUG(1, ("Could not create socket directory\n"));
 247                 TALLOC_FREE(result);
 248                 return NT_STATUS_ACCESS_DENIED;
 249         }
 250         TALLOC_FREE(socket_dir);
 251
 252         unlink(socket_address.sun_path);
 253
 254         generate_random_buffer((uint8_t *)&cookie, sizeof(cookie));
 255
 256         ret = unix_msg_init(&socket_address, ctx->msg_callbacks, 1024, cookie,
 257                             messaging_dgm_recv, ctx, &ctx->dgm_ctx);
 258         if (ret != 0) {
 259                 DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
 260                 TALLOC_FREE(result);
 261                 return map_nt_error_from_unix(ret);
 262         }
 263         talloc_set_destructor(ctx, messaging_dgm_context_destructor);
 264
 265         *presult = result;
 266         return NT_STATUS_OK;
 267
 268 fail_nomem:
 269         TALLOC_FREE(result);
 270         return NT_STATUS_NO_MEMORY;
 271 }
 272
 273 static int messaging_dgm_context_destructor(struct messaging_dgm_context *c)
 274 {
 275         struct server_id pid = messaging_server_id(c->msg_ctx);
 276
 277         /*
 278          * First delete the socket to avoid races. The lockfile is the
 279          * indicator that we're still around.
 280          */
 281         unix_msg_free(c->dgm_ctx);
 282
 283         if (getpid() == pid.pid) {
 284                 (void)messaging_dgm_lockfile_remove(c, c->cache_dir, pid.pid);
 285         }
 286         close(c->lockfile_fd);
 287         return 0;
 288 }
 289
 290 static int messaging_dgm_send(struct server_id src,
 291                               struct server_id pid, int msg_type,
 292                               const struct iovec *iov, int iovlen,
 293                               struct messaging_backend *backend)
 294 {
 295         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 296                 backend->private_data, struct messaging_dgm_context);
 297         struct messaging_dgm_hdr hdr;
 298         struct iovec iov2[iovlen + 1];
 299         struct server_id_buf idbuf;
 300         struct sockaddr_un dst;
 301         ssize_t dst_pathlen;
 302         int ret;
 303
 304         dst = (struct sockaddr_un) { .sun_family = AF_UNIX };
 305
 306         dst_pathlen = snprintf(dst.sun_path, sizeof(dst.sun_path),
 307                                "%s/msg/%u", ctx->cache_dir, (unsigned)pid.pid);
 308         if (dst_pathlen >= sizeof(dst.sun_path)) {
 309                 return ENAMETOOLONG;
 310         }
 311
 312         hdr.msg_version = MESSAGE_VERSION;
 313         hdr.msg_type = msg_type & MSG_TYPE_MASK;
 314         hdr.dst = pid;
 315         hdr.src = src;
 316
 317         DEBUG(10, ("%s: Sending message 0x%x to %s\n", __func__,
 318                    (unsigned)hdr.msg_type,
 319                    server_id_str_buf(pid, &idbuf)));
 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, iov2, iovlen + 1);
 327         unbecome_root();
 328
 329         return ret;
 330 }
 331
 332 static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
 333                                uint8_t *msg, size_t msg_len,
 334                                void *private_data)
 335 {
 336         struct messaging_dgm_context *dgm_ctx = talloc_get_type_abort(
 337                 private_data, struct messaging_dgm_context);
 338         struct messaging_dgm_hdr *hdr;
 339         struct messaging_rec rec;
 340         struct server_id_buf idbuf;
 341
 342         if (msg_len < sizeof(*hdr)) {
 343                 DEBUG(1, ("message too short: %u\n", (unsigned)msg_len));
 344                 return;
 345         }
 346
 347         /*
 348          * unix_msg guarantees alignment, so we can cast here
 349          */
 350         hdr = (struct messaging_dgm_hdr *)msg;
 351
 352         rec.msg_version = hdr->msg_version;
 353         rec.msg_type = hdr->msg_type;
 354         rec.dest = hdr->dst;
 355         rec.src = hdr->src;
 356         rec.buf.data = msg + sizeof(*hdr);
 357         rec.buf.length = msg_len - sizeof(*hdr);
 358
 359         DEBUG(10, ("%s: Received message 0x%x len %u from %s\n", __func__,
 360                    (unsigned)hdr->msg_type, (unsigned)rec.buf.length,
 361                    server_id_str_buf(rec.src, &idbuf)));
 362
 363         messaging_dispatch_rec(dgm_ctx->msg_ctx, &rec);
 364 }
 365
 366 int messaging_dgm_cleanup(struct messaging_context *msg_ctx, pid_t pid)
 367 {
 368         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 369         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 370                 be->private_data, struct messaging_dgm_context);
 371         char *lockfile_name, *socket_name;
 372         int fd, ret;
 373         struct flock lck = {};
 374
 375         lockfile_name = talloc_asprintf(talloc_tos(), "%s/lck/%u",
 376                                         ctx->cache_dir, (unsigned)pid);
 377         if (lockfile_name == NULL) {
 378                 return ENOMEM;
 379         }
 380         socket_name = talloc_asprintf(lockfile_name, "%s/msg/%u",
 381                                       ctx->cache_dir, (unsigned)pid);
 382         if (socket_name == NULL) {
 383                 TALLOC_FREE(lockfile_name);
 384                 return ENOMEM;
 385         }
 386
 387         fd = open(lockfile_name, O_NONBLOCK|O_WRONLY, 0);
 388         if (fd == -1) {
 389                 ret = errno;
 390                 DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
 391                            lockfile_name, strerror(ret)));
 392                 return ret;
 393         }
 394
 395         lck.l_type = F_WRLCK;
 396         lck.l_whence = SEEK_SET;
 397         lck.l_start = 0;
 398         lck.l_len = 0;
 399
 400         ret = fcntl(fd, F_SETLK, &lck);
 401         if (ret != 0) {
 402                 ret = errno;
 403                 DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
 404                            strerror(ret)));
 405                 TALLOC_FREE(lockfile_name);
 406                 close(fd);
 407                 return ret;
 408         }
 409
 410         (void)unlink(socket_name);
 411         (void)unlink(lockfile_name);
 412         (void)close(fd);
 413
 414         TALLOC_FREE(lockfile_name);
 415         return 0;
 416 }
 417
 418 int messaging_dgm_wipe(struct messaging_context *msg_ctx)
 419 {
 420         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 421         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 422                 be->private_data, struct messaging_dgm_context);
 423         char *msgdir_name;
 424         DIR *msgdir;
 425         struct dirent *dp;
 426         pid_t our_pid = getpid();
 427         int ret;
 428
 429         /*
 430          * We scan the socket directory and not the lock directory. Otherwise
 431          * we would race against messaging_dgm_lockfile_create's open(O_CREAT)
 432          * and fcntl(SETLK).
 433          */
 434
 435         msgdir_name = talloc_asprintf(talloc_tos(), "%s/msg", ctx->cache_dir);
 436         if (msgdir_name == NULL) {
 437                 return ENOMEM;
 438         }
 439
 440         msgdir = opendir(msgdir_name);
 441         if (msgdir == NULL) {
 442                 ret = errno;
 443                 TALLOC_FREE(msgdir_name);
 444                 return ret;
 445         }
 446         TALLOC_FREE(msgdir_name);
 447
 448         while ((dp = readdir(msgdir)) != NULL) {
 449                 unsigned long pid;
 450
 451                 pid = strtoul(dp->d_name, NULL, 10);
 452                 if (pid == 0) {
 453                         /*
 454                          * . and .. and other malformed entries
 455                          */
 456                         continue;
 457                 }
 458                 if (pid == our_pid) {
 459                         /*
 460                          * fcntl(F_GETLK) will succeed for ourselves, we hold
 461                          * that lock ourselves.
 462                          */
 463                         continue;
 464                 }
 465
 466                 ret = messaging_dgm_cleanup(msg_ctx, pid);
 467                 DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
 468                            pid, ret ? strerror(ret) : "ok"));
 469         }
 470         closedir(msgdir);
 471
 472         return 0;
 473 }
 474
 475 void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
 476                                             struct messaging_context *msg_ctx,
 477                                             struct tevent_context *ev)
 478 {
 479         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 480         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 481                 be->private_data, struct messaging_dgm_context);
 482         return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
 483 }