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(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;
 182         struct sockaddr_un socket_address;
 183         size_t sockname_len;
 184         uint64_t cookie;
 185
 186         cache_dir = lp_cache_directory();
 187         if (cache_dir == NULL) {
 188                 NTSTATUS status = map_nt_error_from_unix(errno);
 189                 return status;
 190         }
 191
 192         result = talloc(mem_ctx, struct messaging_backend);
 193         if (result == NULL) {
 194                 goto fail_nomem;
 195         }
 196         ctx = talloc_zero(result, struct messaging_dgm_context);
 197         if (ctx == NULL) {
 198                 goto fail_nomem;
 199         }
 200
 201         result->private_data = ctx;
 202         result->send_fn = messaging_dgm_send;
 203         ctx->msg_ctx = msg_ctx;
 204
 205         ctx->cache_dir = talloc_strdup(ctx, cache_dir);
 206         if (ctx->cache_dir == NULL) {
 207                 goto fail_nomem;
 208         }
 209         socket_dir = talloc_asprintf(ctx, "%s/msg", cache_dir);
 210         if (socket_dir == NULL) {
 211                 goto fail_nomem;
 212         }
 213
 214         socket_address = (struct sockaddr_un) { .sun_family = AF_UNIX };
 215         sockname_len = snprintf(socket_address.sun_path,
 216                                 sizeof(socket_address.sun_path),
 217                                 "%s/%u", socket_dir, (unsigned)pid.pid);
 218         if (sockname_len >= sizeof(socket_address.sun_path)) {
 219                 TALLOC_FREE(result);
 220                 return NT_STATUS_NAME_TOO_LONG;
 221         }
 222
 223         sec_init();
 224
 225         ret = messaging_dgm_lockfile_create(ctx, cache_dir, pid.pid,
 226                                             &ctx->lockfile_fd, pid.unique_id);
 227         if (ret != 0) {
 228                 DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
 229                           __func__, strerror(ret)));
 230                 TALLOC_FREE(result);
 231                 return map_nt_error_from_unix(ret);
 232         }
 233
 234         ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
 235         if (ctx->msg_callbacks == NULL) {
 236                 TALLOC_FREE(result);
 237                 return NT_STATUS_NO_MEMORY;
 238         }
 239
 240         ctx->tevent_handle = poll_funcs_tevent_register(
 241                 ctx, ctx->msg_callbacks,
 242                 messaging_tevent_context(msg_ctx));
 243         if (ctx->tevent_handle == NULL) {
 244                 TALLOC_FREE(result);
 245                 return NT_STATUS_NO_MEMORY;
 246         }
 247
 248         ok = directory_create_or_exist_strict(socket_dir, sec_initial_uid(),
 249                                               0700);
 250         if (!ok) {
 251                 DEBUG(1, ("Could not create socket directory\n"));
 252                 TALLOC_FREE(result);
 253                 return NT_STATUS_ACCESS_DENIED;
 254         }
 255         TALLOC_FREE(socket_dir);
 256
 257         unlink(socket_address.sun_path);
 258
 259         generate_random_buffer((uint8_t *)&cookie, sizeof(cookie));
 260
 261         ret = unix_msg_init(&socket_address, ctx->msg_callbacks, 1024, cookie,
 262                             messaging_dgm_recv, ctx, &ctx->dgm_ctx);
 263         if (ret != 0) {
 264                 DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
 265                 TALLOC_FREE(result);
 266                 return map_nt_error_from_unix(ret);
 267         }
 268         talloc_set_destructor(ctx, messaging_dgm_context_destructor);
 269
 270         *presult = result;
 271         return NT_STATUS_OK;
 272
 273 fail_nomem:
 274         TALLOC_FREE(result);
 275         return NT_STATUS_NO_MEMORY;
 276 }
 277
 278 static int messaging_dgm_context_destructor(struct messaging_dgm_context *c)
 279 {
 280         struct server_id pid = messaging_server_id(c->msg_ctx);
 281
 282         /*
 283          * First delete the socket to avoid races. The lockfile is the
 284          * indicator that we're still around.
 285          */
 286         unix_msg_free(c->dgm_ctx);
 287
 288         if (getpid() == pid.pid) {
 289                 (void)messaging_dgm_lockfile_remove(c->cache_dir, pid.pid);
 290         }
 291         close(c->lockfile_fd);
 292         return 0;
 293 }
 294
 295 static int messaging_dgm_send(struct server_id src,
 296                               struct server_id pid, int msg_type,
 297                               const struct iovec *iov, int iovlen,
 298                               struct messaging_backend *backend)
 299 {
 300         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 301                 backend->private_data, struct messaging_dgm_context);
 302         struct messaging_dgm_hdr hdr;
 303         struct iovec iov2[iovlen + 1];
 304         struct server_id_buf idbuf;
 305         struct sockaddr_un dst;
 306         ssize_t dst_pathlen;
 307         int ret;
 308
 309         dst = (struct sockaddr_un) { .sun_family = AF_UNIX };
 310
 311         dst_pathlen = snprintf(dst.sun_path, sizeof(dst.sun_path),
 312                                "%s/msg/%u", ctx->cache_dir, (unsigned)pid.pid);
 313         if (dst_pathlen >= sizeof(dst.sun_path)) {
 314                 return ENAMETOOLONG;
 315         }
 316
 317         hdr.msg_version = MESSAGE_VERSION;
 318         hdr.msg_type = msg_type & MSG_TYPE_MASK;
 319         hdr.dst = pid;
 320         hdr.src = src;
 321
 322         DEBUG(10, ("%s: Sending message 0x%x to %s\n", __func__,
 323                    (unsigned)hdr.msg_type,
 324                    server_id_str_buf(pid, &idbuf)));
 325
 326         iov2[0].iov_base = &hdr;
 327         iov2[0].iov_len = sizeof(hdr);
 328         memcpy(iov2+1, iov, iovlen*sizeof(struct iovec));
 329
 330         become_root();
 331         ret = unix_msg_send(ctx->dgm_ctx, &dst, iov2, iovlen + 1);
 332         unbecome_root();
 333
 334         return ret;
 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         struct server_id_buf idbuf;
 346
 347         if (msg_len < sizeof(*hdr)) {
 348                 DEBUG(1, ("message too short: %u\n", (unsigned)msg_len));
 349                 return;
 350         }
 351
 352         /*
 353          * unix_msg guarantees alignment, so we can cast here
 354          */
 355         hdr = (struct messaging_dgm_hdr *)msg;
 356
 357         rec.msg_version = hdr->msg_version;
 358         rec.msg_type = hdr->msg_type;
 359         rec.dest = hdr->dst;
 360         rec.src = hdr->src;
 361         rec.buf.data = msg + sizeof(*hdr);
 362         rec.buf.length = msg_len - sizeof(*hdr);
 363
 364         DEBUG(10, ("%s: Received message 0x%x len %u from %s\n", __func__,
 365                    (unsigned)hdr->msg_type, (unsigned)rec.buf.length,
 366                    server_id_str_buf(rec.src, &idbuf)));
 367
 368         messaging_dispatch_rec(dgm_ctx->msg_ctx, &rec);
 369 }
 370
 371 int messaging_dgm_cleanup(struct messaging_context *msg_ctx, pid_t pid)
 372 {
 373         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 374         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 375                 be->private_data, struct messaging_dgm_context);
 376         char *lockfile_name, *socket_name;
 377         int fd, ret;
 378         struct flock lck = {};
 379
 380         lockfile_name = talloc_asprintf(talloc_tos(), "%s/lck/%u",
 381                                         ctx->cache_dir, (unsigned)pid);
 382         if (lockfile_name == NULL) {
 383                 return ENOMEM;
 384         }
 385         socket_name = talloc_asprintf(lockfile_name, "%s/msg/%u",
 386                                       ctx->cache_dir, (unsigned)pid);
 387         if (socket_name == NULL) {
 388                 TALLOC_FREE(lockfile_name);
 389                 return ENOMEM;
 390         }
 391
 392         fd = open(lockfile_name, O_NONBLOCK|O_WRONLY, 0);
 393         if (fd == -1) {
 394                 ret = errno;
 395                 DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
 396                            lockfile_name, strerror(ret)));
 397                 return ret;
 398         }
 399
 400         lck.l_type = F_WRLCK;
 401         lck.l_whence = SEEK_SET;
 402         lck.l_start = 0;
 403         lck.l_len = 0;
 404
 405         ret = fcntl(fd, F_SETLK, &lck);
 406         if (ret != 0) {
 407                 ret = errno;
 408                 DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
 409                            strerror(ret)));
 410                 TALLOC_FREE(lockfile_name);
 411                 close(fd);
 412                 return ret;
 413         }
 414
 415         (void)unlink(socket_name);
 416         (void)unlink(lockfile_name);
 417         (void)close(fd);
 418
 419         TALLOC_FREE(lockfile_name);
 420         return 0;
 421 }
 422
 423 NTSTATUS messaging_dgm_wipe(struct messaging_context *msg_ctx)
 424 {
 425         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 426         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 427                 be->private_data, struct messaging_dgm_context);
 428         char *msgdir_name;
 429         DIR *msgdir;
 430         struct dirent *dp;
 431         pid_t our_pid = getpid();
 432
 433         /*
 434          * We scan the socket directory and not the lock directory. Otherwise
 435          * we would race against messaging_dgm_lockfile_create's open(O_CREAT)
 436          * and fcntl(SETLK).
 437          */
 438
 439         msgdir_name = talloc_asprintf(talloc_tos(), "%s/msg", ctx->cache_dir);
 440         if (msgdir_name == NULL) {
 441                 return NT_STATUS_NO_MEMORY;
 442         }
 443
 444         msgdir = opendir(msgdir_name);
 445         TALLOC_FREE(msgdir_name);
 446         if (msgdir == NULL) {
 447                 return map_nt_error_from_unix(errno);
 448         }
 449
 450         while ((dp = readdir(msgdir)) != NULL) {
 451                 unsigned long pid;
 452
 453                 pid = strtoul(dp->d_name, NULL, 10);
 454                 if (pid == 0) {
 455                         /*
 456                          * . and .. and other malformed entries
 457                          */
 458                         continue;
 459                 }
 460                 if (pid == our_pid) {
 461                         /*
 462                          * fcntl(F_GETLK) will succeed for ourselves, we hold
 463                          * that lock ourselves.
 464                          */
 465                         continue;
 466                 }
 467
 468                 ret = messaging_dgm_cleanup(msg_ctx, pid);
 469                 DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
 470                            pid, ret ? strerror(ret) : "ok"));
 471         }
 472         closedir(msgdir);
 473
 474         return NT_STATUS_OK;
 475 }
 476
 477 void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
 478                                             struct messaging_context *msg_ctx,
 479                                             struct tevent_context *ev)
 480 {
 481         struct messaging_backend *be = messaging_local_backend(msg_ctx);
 482         struct messaging_dgm_context *ctx = talloc_get_type_abort(
 483                 be->private_data, struct messaging_dgm_context);
 484         return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
 485 }