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 int 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                 return errno;
 186         }
 187
 188         result = talloc(mem_ctx, struct messaging_backend);
 189         if (result == NULL) {
 190                 goto fail_nomem;
 191         }
 192         ctx = talloc_zero(result, struct messaging_dgm_context);
 193         if (ctx == NULL) {
 194                 goto fail_nomem;
 195         }
 196
 197         result->private_data = ctx;
 198         result->send_fn = messaging_dgm_send;
 199         ctx->msg_ctx = msg_ctx;
 200
 201         ctx->cache_dir = talloc_strdup(ctx, cache_dir);
 202         if (ctx->cache_dir == NULL) {
 203                 goto fail_nomem;
 204         }
 205         socket_dir = talloc_asprintf(ctx, "%s/msg", cache_dir);
 206         if (socket_dir == NULL) {
 207                 goto fail_nomem;
 208         }
 209
 210         socket_address = (struct sockaddr_un) { .sun_family = AF_UNIX };
 211         sockname_len = snprintf(socket_address.sun_path,
 212                                 sizeof(socket_address.sun_path),
 213                                 "%s/%u", socket_dir, (unsigned)pid.pid);
 214         if (sockname_len >= sizeof(socket_address.sun_path)) {
 215                 TALLOC_FREE(result);
 216                 return ENAMETOOLONG;
 217         }
 218
 219         sec_init();
 220
 221         ret = messaging_dgm_lockfile_create(ctx, cache_dir, pid.pid,
 222                                             &ctx->lockfile_fd, pid.unique_id);
 223         if (ret != 0) {
 224                 DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
 225                           __func__, strerror(ret)));
 226                 TALLOC_FREE(result);
 227                 return ret;
 228         }
 229
 230         ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
 231         if (ctx->msg_callbacks == NULL) {
 232                 goto fail_nomem;
 233         }
 234
 235         ctx->tevent_handle = poll_funcs_tevent_register(
 236                 ctx, ctx->msg_callbacks,
 237                 messaging_tevent_context(msg_ctx));
 238         if (ctx->tevent_handle == NULL) {
 239                 goto fail_nomem;
 240         }
 241
 242         ok = directory_create_or_exist_strict(socket_dir, sec_initial_uid(),
 243                                               0700);
 244         if (!ok) {
 245                 DEBUG(1, ("Could not create socket directory\n"));
 246                 TALLOC_FREE(result);
 247                 return EACCES;
 248         }
 249         TALLOC_FREE(socket_dir);
 250
 251         unlink(socket_address.sun_path);
 252
 253         generate_random_buffer((uint8_t *)&cookie, sizeof(cookie));
 254
 255         ret = unix_msg_init(&socket_address, ctx->msg_callbacks, 1024, cookie,
 256                             messaging_dgm_recv, ctx, &ctx->dgm_ctx);
 257         if (ret != 0) {
 258                 DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
 259                 TALLOC_FREE(result);
 260                 return ret;
 261         }
 262         talloc_set_destructor(ctx, messaging_dgm_context_destructor);
 263
 264         *presult = result;
 265         return 0;
 266
 267 fail_nomem:
 268         TALLOC_FREE(result);
 269         return ENOMEM;
 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, c->cache_dir, pid.pid);
 284         }
 285         close(c->lockfile_fd);
 286         return 0;
 287 }
 288
 289 static int messaging_dgm_send(struct server_id src,
 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         struct messaging_dgm_hdr hdr;
 297         struct iovec iov2[iovlen + 1];
 298         struct server_id_buf idbuf;
 299         struct sockaddr_un dst;
 300         ssize_t dst_pathlen;
 301         int ret;
 302
 303         dst = (struct sockaddr_un) { .sun_family = AF_UNIX };
 304
 305         dst_pathlen = snprintf(dst.sun_path, sizeof(dst.sun_path),
 306                                "%s/msg/%u", ctx->cache_dir, (unsigned)pid.pid);
 307         if (dst_pathlen >= sizeof(dst.sun_path)) {
 308                 return ENAMETOOLONG;
 309         }
 310
 311         hdr.msg_version = MESSAGE_VERSION;
 312         hdr.msg_type = msg_type & MSG_TYPE_MASK;
 313         hdr.dst = pid;
 314         hdr.src = src;
 315
 316         DEBUG(10, ("%s: Sending message 0x%x to %s\n", __func__,
 317                    (unsigned)hdr.msg_type,
 318                    server_id_str_buf(pid, &idbuf)));
 319
 320         iov2[0].iov_base = &hdr;
 321         iov2[0].iov_len = sizeof(hdr);
 322         memcpy(iov2+1, iov, iovlen*sizeof(struct iovec));
 323
 324         become_root();
 325         ret = unix_msg_send(ctx->dgm_ctx, &dst, iov2, iovlen + 1);
 326         unbecome_root();
 327
 328         return ret;
 329 }
 330
 331 static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
 332                                uint8_t *msg, size_t msg_len,
 333                                void *private_data)
 334 {
 335         struct messaging_dgm_context *dgm_ctx = talloc_get_type_abort(
 336                 private_data, struct messaging_dgm_context);
 337         struct messaging_dgm_hdr *hdr;
 338         struct messaging_rec rec;
 339         struct server_id_buf idbuf;
 340
 341         if (msg_len < sizeof(*hdr)) {
 342                 DEBUG(1, ("message too short: %u\n", (unsigned)msg_len));
 343                 return;
 344         }
 345
 346         /*
 347          * unix_msg guarantees alignment, so we can cast here
 348          */
 349         hdr = (struct messaging_dgm_hdr *)msg;
 350
 351         rec.msg_version = hdr->msg_version;
 352         rec.msg_type = hdr->msg_type;
 353         rec.dest = hdr->dst;
 354         rec.src = hdr->src;
 355         rec.buf.data = msg + sizeof(*hdr);
 356         rec.buf.length = msg_len - sizeof(*hdr);
 357
 358         DEBUG(10, ("%s: Received message 0x%x len %u from %s\n", __func__,
 359                    (unsigned)hdr->msg_type, (unsigned)rec.buf.length,
 360                    server_id_str_buf(rec.src, &idbuf)));
 361
 362         messaging_dispatch_rec(dgm_ctx->msg_ctx, &rec);
 363 }
 364
 365 int messaging_dgm_cleanup(struct messaging_context *msg_ctx, pid_t pid)
 366 {
 367         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 368         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 369                 be->private_data, struct messaging_dgm_context);
 370         char *lockfile_name, *socket_name;
 371         int fd, ret;
 372         struct flock lck = {};
 373
 374         lockfile_name = talloc_asprintf(talloc_tos(), "%s/lck/%u",
 375                                         ctx->cache_dir, (unsigned)pid);
 376         if (lockfile_name == NULL) {
 377                 return ENOMEM;
 378         }
 379         socket_name = talloc_asprintf(lockfile_name, "%s/msg/%u",
 380                                       ctx->cache_dir, (unsigned)pid);
 381         if (socket_name == NULL) {
 382                 TALLOC_FREE(lockfile_name);
 383                 return ENOMEM;
 384         }
 385
 386         fd = open(lockfile_name, O_NONBLOCK|O_WRONLY, 0);
 387         if (fd == -1) {
 388                 ret = errno;
 389                 DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
 390                            lockfile_name, strerror(ret)));
 391                 return ret;
 392         }
 393
 394         lck.l_type = F_WRLCK;
 395         lck.l_whence = SEEK_SET;
 396         lck.l_start = 0;
 397         lck.l_len = 0;
 398
 399         ret = fcntl(fd, F_SETLK, &lck);
 400         if (ret != 0) {
 401                 ret = errno;
 402                 DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
 403                            strerror(ret)));
 404                 TALLOC_FREE(lockfile_name);
 405                 close(fd);
 406                 return ret;
 407         }
 408
 409         (void)unlink(socket_name);
 410         (void)unlink(lockfile_name);
 411         (void)close(fd);
 412
 413         TALLOC_FREE(lockfile_name);
 414         return 0;
 415 }
 416
 417 int messaging_dgm_wipe(struct messaging_context *msg_ctx)
 418 {
 419         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 420         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 421                 be->private_data, struct messaging_dgm_context);
 422         char *msgdir_name;
 423         DIR *msgdir;
 424         struct dirent *dp;
 425         pid_t our_pid = getpid();
 426         int ret;
 427
 428         /*
 429          * We scan the socket directory and not the lock directory. Otherwise
 430          * we would race against messaging_dgm_lockfile_create's open(O_CREAT)
 431          * and fcntl(SETLK).
 432          */
 433
 434         msgdir_name = talloc_asprintf(talloc_tos(), "%s/msg", ctx->cache_dir);
 435         if (msgdir_name == NULL) {
 436                 return ENOMEM;
 437         }
 438
 439         msgdir = opendir(msgdir_name);
 440         if (msgdir == NULL) {
 441                 ret = errno;
 442                 TALLOC_FREE(msgdir_name);
 443                 return ret;
 444         }
 445         TALLOC_FREE(msgdir_name);
 446
 447         while ((dp = readdir(msgdir)) != NULL) {
 448                 unsigned long pid;
 449
 450                 pid = strtoul(dp->d_name, NULL, 10);
 451                 if (pid == 0) {
 452                         /*
 453                          * . and .. and other malformed entries
 454                          */
 455                         continue;
 456                 }
 457                 if (pid == our_pid) {
 458                         /*
 459                          * fcntl(F_GETLK) will succeed for ourselves, we hold
 460                          * that lock ourselves.
 461                          */
 462                         continue;
 463                 }
 464
 465                 ret = messaging_dgm_cleanup(msg_ctx, pid);
 466                 DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
 467                            pid, ret ? strerror(ret) : "ok"));
 468         }
 469         closedir(msgdir);
 470
 471         return 0;
 472 }
 473
 474 void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
 475                                             struct messaging_context *msg_ctx,
 476                                             struct tevent_context *ev)
 477 {
 478         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 479         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 480                 be->private_data, struct messaging_dgm_context);
 481         return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
 482 }