scsi/qemu-pr-helper.c

   1 /*
   2  * Privileged helper to handle persistent reservation commands for QEMU
   3  *
   4  * Copyright (C) 2017 Red Hat, Inc. <pbonzini@redhat.com>
   5  *
   6  * Author: Paolo Bonzini <pbonzini@redhat.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; under version 2 of the License.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include <getopt.h>
  23 #include <sys/ioctl.h>
  24 #include <linux/dm-ioctl.h>
  25 #include <scsi/sg.h>
  26
  27 #ifdef CONFIG_LIBCAP
  28 #include <cap-ng.h>
  29 #endif
  30 #include <pwd.h>
  31 #include <grp.h>
  32
  33 #ifdef CONFIG_MPATH
  34 #include <libudev.h>
  35 #include <mpath_cmd.h>
  36 #include <mpath_persist.h>
  37 #endif
  38
  39 #include "qapi/error.h"
  40 #include "qemu-common.h"
  41 #include "qemu/cutils.h"
  42 #include "qemu/main-loop.h"
  43 #include "qemu/error-report.h"
  44 #include "qemu/config-file.h"
  45 #include "qemu/bswap.h"
  46 #include "qemu/log.h"
  47 #include "qemu/systemd.h"
  48 #include "qapi/util.h"
  49 #include "qapi/qmp/qstring.h"
  50 #include "io/channel-socket.h"
  51 #include "trace/control.h"
  52 #include "qemu-version.h"
  53
  54 #include "block/aio.h"
  55 #include "block/thread-pool.h"
  56
  57 #include "scsi/constants.h"
  58 #include "scsi/utils.h"
  59 #include "pr-helper.h"
  60
  61 #define PR_OUT_FIXED_PARAM_SIZE 24
  62
  63 static char *socket_path;
  64 static char *pidfile;
  65 static enum { RUNNING, TERMINATE, TERMINATING } state;
  66 static QIOChannelSocket *server_ioc;
  67 static int server_watch;
  68 static int num_active_sockets = 1;
  69 static int noisy;
  70 static int verbose;
  71
  72 #ifdef CONFIG_LIBCAP
  73 static int uid = -1;
  74 static int gid = -1;
  75 #endif
  76
  77 static void usage(const char *name)
  78 {
  79     (printf) (
  80 "Usage: %s [OPTIONS] FILE\n"
  81 "Persistent Reservation helper program for QEMU\n"
  82 "\n"
  83 "  -h, --help                display this help and exit\n"
  84 "  -V, --version             output version information and exit\n"
  85 "\n"
  86 "  -d, --daemon              run in the background\n"
  87 "  -f, --pidfile=PATH        PID file when running as a daemon\n"
  88 "                            (default '%s')\n"
  89 "  -k, --socket=PATH         path to the unix socket\n"
  90 "                            (default '%s')\n"
  91 "  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
  92 "                            specify tracing options\n"
  93 #ifdef CONFIG_LIBCAP
  94 "  -u, --user=USER           user to drop privileges to\n"
  95 "  -g, --group=GROUP         group to drop privileges to\n"
  96 #endif
  97 "\n"
  98 QEMU_HELP_BOTTOM "\n"
  99     , name, pidfile, socket_path);
 100 }
 101
 102 static void version(const char *name)
 103 {
 104     printf(
 105 "%s " QEMU_FULL_VERSION "\n"
 106 "Written by Paolo Bonzini.\n"
 107 "\n"
 108 QEMU_COPYRIGHT "\n"
 109 "This is free software; see the source for copying conditions.  There is NO\n"
 110 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 111     , name);
 112 }
 113
 114 static void write_pidfile(void)
 115 {
 116     int pidfd;
 117     char pidstr[32];
 118
 119     pidfd = qemu_open(pidfile, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR);
 120     if (pidfd == -1) {
 121         error_report("Cannot open pid file, %s", strerror(errno));
 122         exit(EXIT_FAILURE);
 123     }
 124
 125     if (lockf(pidfd, F_TLOCK, 0)) {
 126         error_report("Cannot lock pid file, %s", strerror(errno));
 127         goto fail;
 128     }
 129     if (ftruncate(pidfd, 0)) {
 130         error_report("Failed to truncate pid file");
 131         goto fail;
 132     }
 133
 134     snprintf(pidstr, sizeof(pidstr), "%d\n", getpid());
 135     if (write(pidfd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
 136         error_report("Failed to write pid file");
 137         goto fail;
 138     }
 139     return;
 140
 141 fail:
 142     unlink(pidfile);
 143     close(pidfd);
 144     exit(EXIT_FAILURE);
 145 }
 146
 147 /* SG_IO support */
 148
 149 typedef struct PRHelperSGIOData {
 150     int fd;
 151     const uint8_t *cdb;
 152     uint8_t *sense;
 153     uint8_t *buf;
 154     int sz;              /* input/output */
 155     int dir;
 156 } PRHelperSGIOData;
 157
 158 static int do_sgio_worker(void *opaque)
 159 {
 160     PRHelperSGIOData *data = opaque;
 161     struct sg_io_hdr io_hdr;
 162     int ret;
 163     int status;
 164     SCSISense sense_code;
 165
 166     memset(data->sense, 0, PR_HELPER_SENSE_SIZE);
 167     memset(&io_hdr, 0, sizeof(io_hdr));
 168     io_hdr.interface_id = 'S';
 169     io_hdr.cmd_len = PR_HELPER_CDB_SIZE;
 170     io_hdr.cmdp = (uint8_t *)data->cdb;
 171     io_hdr.sbp = data->sense;
 172     io_hdr.mx_sb_len = PR_HELPER_SENSE_SIZE;
 173     io_hdr.timeout = 1;
 174     io_hdr.dxfer_direction = data->dir;
 175     io_hdr.dxferp = (char *)data->buf;
 176     io_hdr.dxfer_len = data->sz;
 177     ret = ioctl(data->fd, SG_IO, &io_hdr);
 178     status = sg_io_sense_from_errno(ret < 0 ? errno : 0, &io_hdr,
 179                                     &sense_code);
 180     if (status == GOOD) {
 181         data->sz -= io_hdr.resid;
 182     } else {
 183         data->sz = 0;
 184     }
 185
 186     if (status == CHECK_CONDITION &&
 187         !(io_hdr.driver_status & SG_ERR_DRIVER_SENSE)) {
 188         scsi_build_sense(data->sense, sense_code);
 189     }
 190
 191     return status;
 192 }
 193
 194 static int do_sgio(int fd, const uint8_t *cdb, uint8_t *sense,
 195                     uint8_t *buf, int *sz, int dir)
 196 {
 197     ThreadPool *pool = aio_get_thread_pool(qemu_get_aio_context());
 198     int r;
 199
 200     PRHelperSGIOData data = {
 201         .fd = fd,
 202         .cdb = cdb,
 203         .sense = sense,
 204         .buf = buf,
 205         .sz = *sz,
 206         .dir = dir,
 207     };
 208
 209     r = thread_pool_submit_co(pool, do_sgio_worker, &data);
 210     *sz = data.sz;
 211     return r;
 212 }
 213
 214 /* Device mapper interface */
 215
 216 #ifdef CONFIG_MPATH
 217 #define CONTROL_PATH "/dev/mapper/control"
 218
 219 typedef struct DMData {
 220     struct dm_ioctl dm;
 221     uint8_t data[1024];
 222 } DMData;
 223
 224 static int control_fd;
 225
 226 static void *dm_ioctl(int ioc, struct dm_ioctl *dm)
 227 {
 228     static DMData d;
 229     memcpy(&d.dm, dm, sizeof(d.dm));
 230     QEMU_BUILD_BUG_ON(sizeof(d.data) < sizeof(struct dm_target_spec));
 231
 232     d.dm.version[0] = DM_VERSION_MAJOR;
 233     d.dm.version[1] = 0;
 234     d.dm.version[2] = 0;
 235     d.dm.data_size = 1024;
 236     d.dm.data_start = offsetof(DMData, data);
 237     if (ioctl(control_fd, ioc, &d) < 0) {
 238         return NULL;
 239     }
 240     memcpy(dm, &d.dm, sizeof(d.dm));
 241     return &d.data;
 242 }
 243
 244 static void *dm_dev_ioctl(int fd, int ioc, struct dm_ioctl *dm)
 245 {
 246     struct stat st;
 247     int r;
 248
 249     r = fstat(fd, &st);
 250     if (r < 0) {
 251         perror("fstat");
 252         exit(1);
 253     }
 254
 255     dm->dev = st.st_rdev;
 256     return dm_ioctl(ioc, dm);
 257 }
 258
 259 static void dm_init(void)
 260 {
 261     control_fd = open(CONTROL_PATH, O_RDWR);
 262     if (control_fd < 0) {
 263         perror("Cannot open " CONTROL_PATH);
 264         exit(1);
 265     }
 266     struct dm_ioctl dm = { 0 };
 267     if (!dm_ioctl(DM_VERSION, &dm)) {
 268         perror("ioctl");
 269         exit(1);
 270     }
 271     if (dm.version[0] != DM_VERSION_MAJOR) {
 272         fprintf(stderr, "Unsupported device mapper interface");
 273         exit(1);
 274     }
 275 }
 276
 277 /* Variables required by libmultipath and libmpathpersist.  */
 278 QEMU_BUILD_BUG_ON(PR_HELPER_DATA_SIZE > MPATH_MAX_PARAM_LEN);
 279 static struct config *multipath_conf;
 280 unsigned mpath_mx_alloc_len = PR_HELPER_DATA_SIZE;
 281 int logsink;
 282 struct udev *udev;
 283
 284 extern struct config *get_multipath_config(void);
 285 struct config *get_multipath_config(void)
 286 {
 287     return multipath_conf;
 288 }
 289
 290 extern void put_multipath_config(struct config *conf);
 291 void put_multipath_config(struct config *conf)
 292 {
 293 }
 294
 295 static void multipath_pr_init(void)
 296 {
 297     udev = udev_new();
 298     multipath_conf = mpath_lib_init();
 299 }
 300
 301 static int is_mpath(int fd)
 302 {
 303     struct dm_ioctl dm = { .flags = DM_NOFLUSH_FLAG };
 304     struct dm_target_spec *tgt;
 305
 306     tgt = dm_dev_ioctl(fd, DM_TABLE_STATUS, &dm);
 307     if (!tgt) {
 308         if (errno == ENXIO) {
 309             return 0;
 310         }
 311         perror("ioctl");
 312         exit(EXIT_FAILURE);
 313     }
 314     return !strncmp(tgt->target_type, "multipath", DM_MAX_TYPE_NAME);
 315 }
 316
 317 static SCSISense mpath_generic_sense(int r)
 318 {
 319     switch (r) {
 320     case MPATH_PR_SENSE_NOT_READY:
 321          return SENSE_CODE(NOT_READY);
 322     case MPATH_PR_SENSE_MEDIUM_ERROR:
 323          return SENSE_CODE(READ_ERROR);
 324     case MPATH_PR_SENSE_HARDWARE_ERROR:
 325          return SENSE_CODE(TARGET_FAILURE);
 326     case MPATH_PR_SENSE_ABORTED_COMMAND:
 327          return SENSE_CODE(IO_ERROR);
 328     default:
 329          abort();
 330     }
 331 }
 332
 333 static int mpath_reconstruct_sense(int fd, int r, uint8_t *sense)
 334 {
 335     switch (r) {
 336     case MPATH_PR_SUCCESS:
 337         return GOOD;
 338     case MPATH_PR_SENSE_NOT_READY:
 339     case MPATH_PR_SENSE_MEDIUM_ERROR:
 340     case MPATH_PR_SENSE_HARDWARE_ERROR:
 341     case MPATH_PR_SENSE_ABORTED_COMMAND:
 342         {
 343             /* libmpathpersist ate the exact sense.  Try to find it by
 344              * issuing TEST UNIT READY.
 345              */
 346             uint8_t cdb[6] = { TEST_UNIT_READY };
 347             int sz = 0;
 348             int r = do_sgio(fd, cdb, sense, NULL, &sz, SG_DXFER_NONE);
 349
 350             if (r != GOOD) {
 351                 return r;
 352             }
 353             scsi_build_sense(sense, mpath_generic_sense(r));
 354             return CHECK_CONDITION;
 355         }
 356
 357     case MPATH_PR_SENSE_UNIT_ATTENTION:
 358         /* Congratulations libmpathpersist, you ruined the Unit Attention...
 359          * Return a heavyweight one.
 360          */
 361         scsi_build_sense(sense, SENSE_CODE(SCSI_BUS_RESET));
 362         return CHECK_CONDITION;
 363     case MPATH_PR_SENSE_INVALID_OP:
 364         /* Only one valid sense.  */
 365         scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 366         return CHECK_CONDITION;
 367     case MPATH_PR_ILLEGAL_REQ:
 368         /* Guess.  */
 369         scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 370         return CHECK_CONDITION;
 371     case MPATH_PR_NO_SENSE:
 372         scsi_build_sense(sense, SENSE_CODE(NO_SENSE));
 373         return CHECK_CONDITION;
 374
 375     case MPATH_PR_RESERV_CONFLICT:
 376         return RESERVATION_CONFLICT;
 377
 378     case MPATH_PR_OTHER:
 379     default:
 380         scsi_build_sense(sense, SENSE_CODE(LUN_COMM_FAILURE));
 381         return CHECK_CONDITION;
 382     }
 383 }
 384
 385 static int multipath_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 386                            uint8_t *data, int sz)
 387 {
 388     int rq_servact = cdb[1];
 389     struct prin_resp resp;
 390     size_t written;
 391     int r;
 392
 393     switch (rq_servact) {
 394     case MPATH_PRIN_RKEY_SA:
 395     case MPATH_PRIN_RRES_SA:
 396     case MPATH_PRIN_RCAP_SA:
 397         break;
 398     case MPATH_PRIN_RFSTAT_SA:
 399         /* Nobody implements it anyway, so bail out. */
 400     default:
 401         /* Cannot parse any other output.  */
 402         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 403         return CHECK_CONDITION;
 404     }
 405
 406     r = mpath_persistent_reserve_in(fd, rq_servact, &resp, noisy, verbose);
 407     if (r == MPATH_PR_SUCCESS) {
 408         switch (rq_servact) {
 409         case MPATH_PRIN_RKEY_SA:
 410         case MPATH_PRIN_RRES_SA: {
 411             struct prin_readdescr *out = &resp.prin_descriptor.prin_readkeys;
 412             assert(sz >= 8);
 413             written = MIN(out->additional_length + 8, sz);
 414             stl_be_p(&data[0], out->prgeneration);
 415             stl_be_p(&data[4], out->additional_length);
 416             memcpy(&data[8], out->key_list, written - 8);
 417             break;
 418         }
 419         case MPATH_PRIN_RCAP_SA: {
 420             struct prin_capdescr *out = &resp.prin_descriptor.prin_readcap;
 421             assert(sz >= 6);
 422             written = 6;
 423             stw_be_p(&data[0], out->length);
 424             data[2] = out->flags[0];
 425             data[3] = out->flags[1];
 426             stw_be_p(&data[4], out->pr_type_mask);
 427             break;
 428         }
 429         default:
 430             scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 431             return CHECK_CONDITION;
 432         }
 433         assert(written <= sz);
 434         memset(data + written, 0, sz - written);
 435     }
 436
 437     return mpath_reconstruct_sense(fd, r, sense);
 438 }
 439
 440 static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 441                             const uint8_t *param, int sz)
 442 {
 443     int rq_servact = cdb[1];
 444     int rq_scope = cdb[2] >> 4;
 445     int rq_type = cdb[2] & 0xf;
 446     struct prout_param_descriptor paramp;
 447     char transportids[PR_HELPER_DATA_SIZE];
 448     int r;
 449
 450     switch (rq_servact) {
 451     case MPATH_PROUT_REG_SA:
 452     case MPATH_PROUT_RES_SA:
 453     case MPATH_PROUT_REL_SA:
 454     case MPATH_PROUT_CLEAR_SA:
 455     case MPATH_PROUT_PREE_SA:
 456     case MPATH_PROUT_PREE_AB_SA:
 457     case MPATH_PROUT_REG_IGN_SA:
 458         break;
 459     case MPATH_PROUT_REG_MOV_SA:
 460         /* Not supported by struct prout_param_descriptor.  */
 461     default:
 462         /* Cannot parse any other input.  */
 463         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 464         return CHECK_CONDITION;
 465     }
 466
 467     /* Convert input data, especially transport IDs, to the structs
 468      * used by libmpathpersist (which, of course, will immediately
 469      * do the opposite).
 470      */
 471     memset(&paramp, 0, sizeof(paramp));
 472     memcpy(&paramp.key, &param[0], 8);
 473     memcpy(&paramp.sa_key, &param[8], 8);
 474     paramp.sa_flags = param[20];
 475     if (sz > PR_OUT_FIXED_PARAM_SIZE) {
 476         size_t transportid_len;
 477         int i, j;
 478         if (sz < PR_OUT_FIXED_PARAM_SIZE + 4) {
 479             scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM_LEN));
 480             return CHECK_CONDITION;
 481         }
 482         transportid_len = ldl_be_p(&param[24]) + PR_OUT_FIXED_PARAM_SIZE + 4;
 483         if (transportid_len > sz) {
 484             scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 485             return CHECK_CONDITION;
 486         }
 487         for (i = PR_OUT_FIXED_PARAM_SIZE + 4, j = 0; i < transportid_len; ) {
 488             struct transportid *id = (struct transportid *) &transportids[j];
 489             int len;
 490
 491             id->format_code = param[i] & 0xc0;
 492             id->protocol_id = param[i] & 0x0f;
 493             switch (param[i] & 0xcf) {
 494             case 0:
 495                 /* FC transport.  */
 496                 if (i + 24 > transportid_len) {
 497                     goto illegal_req;
 498                 }
 499                 memcpy(id->n_port_name, &param[i + 8], 8);
 500                 j += offsetof(struct transportid, n_port_name[8]);
 501                 i += 24;
 502                 break;
 503             case 5:
 504             case 0x45:
 505                 /* iSCSI transport.  */
 506                 len = lduw_be_p(&param[i + 2]);
 507                 if (len > 252 || (len & 3) || i + len + 4 > transportid_len) {
 508                     /* For format code 00, the standard says the maximum is 223
 509                      * plus the NUL terminator.  For format code 01 there is no
 510                      * maximum length, but libmpathpersist ignores the first
 511                      * byte of id->iscsi_name so our maximum is 252.
 512                      */
 513                     goto illegal_req;
 514                 }
 515                 if (memchr(&param[i + 4], 0, len) == NULL) {
 516                     goto illegal_req;
 517                 }
 518                 memcpy(id->iscsi_name, &param[i + 2], len + 2);
 519                 j += offsetof(struct transportid, iscsi_name[len + 2]);
 520                 i += len + 4;
 521                 break;
 522             case 6:
 523                 /* SAS transport.  */
 524                 if (i + 24 > transportid_len) {
 525                     goto illegal_req;
 526                 }
 527                 memcpy(id->sas_address, &param[i + 4], 8);
 528                 j += offsetof(struct transportid, sas_address[8]);
 529                 i += 24;
 530                 break;
 531             default:
 532             illegal_req:
 533                 scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 534                 return CHECK_CONDITION;
 535             }
 536
 537             paramp.trnptid_list[paramp.num_transportid++] = id;
 538         }
 539     }
 540
 541     r = mpath_persistent_reserve_out(fd, rq_servact, rq_scope, rq_type,
 542                                      &paramp, noisy, verbose);
 543     return mpath_reconstruct_sense(fd, r, sense);
 544 }
 545 #endif
 546
 547 static int do_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 548                     uint8_t *data, int *resp_sz)
 549 {
 550 #ifdef CONFIG_MPATH
 551     if (is_mpath(fd)) {
 552         /* multipath_pr_in fills the whole input buffer.  */
 553         return multipath_pr_in(fd, cdb, sense, data, *resp_sz);
 554     }
 555 #endif
 556
 557     return do_sgio(fd, cdb, sense, data, resp_sz,
 558                    SG_DXFER_FROM_DEV);
 559 }
 560
 561 static int do_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 562                      const uint8_t *param, int sz)
 563 {
 564     int resp_sz;
 565 #ifdef CONFIG_MPATH
 566     if (is_mpath(fd)) {
 567         return multipath_pr_out(fd, cdb, sense, param, sz);
 568     }
 569 #endif
 570
 571     resp_sz = sz;
 572     return do_sgio(fd, cdb, sense, (uint8_t *)param, &resp_sz,
 573                    SG_DXFER_TO_DEV);
 574 }
 575
 576 /* Client */
 577
 578 typedef struct PRHelperClient {
 579     QIOChannelSocket *ioc;
 580     Coroutine *co;
 581     int fd;
 582     uint8_t data[PR_HELPER_DATA_SIZE];
 583 } PRHelperClient;
 584
 585 typedef struct PRHelperRequest {
 586     int fd;
 587     size_t sz;
 588     uint8_t cdb[PR_HELPER_CDB_SIZE];
 589 } PRHelperRequest;
 590
 591 static int coroutine_fn prh_read(PRHelperClient *client, void *buf, int sz,
 592                                  Error **errp)
 593 {
 594     int ret = 0;
 595
 596     while (sz > 0) {
 597         int *fds = NULL;
 598         size_t nfds = 0;
 599         int i;
 600         struct iovec iov;
 601         ssize_t n_read;
 602
 603         iov.iov_base = buf;
 604         iov.iov_len = sz;
 605         n_read = qio_channel_readv_full(QIO_CHANNEL(client->ioc), &iov, 1,
 606                                         &fds, &nfds, errp);
 607
 608         if (n_read == QIO_CHANNEL_ERR_BLOCK) {
 609             qio_channel_yield(QIO_CHANNEL(client->ioc), G_IO_IN);
 610             continue;
 611         }
 612         if (n_read <= 0) {
 613             ret = n_read ? n_read : -1;
 614             goto err;
 615         }
 616
 617         /* Stash one file descriptor per request.  */
 618         if (nfds) {
 619             bool too_many = false;
 620             for (i = 0; i < nfds; i++) {
 621                 if (client->fd == -1) {
 622                     client->fd = fds[i];
 623                 } else {
 624                     close(fds[i]);
 625                     too_many = true;
 626                 }
 627             }
 628             g_free(fds);
 629             if (too_many) {
 630                 ret = -1;
 631                 goto err;
 632             }
 633         }
 634
 635         buf += n_read;
 636         sz -= n_read;
 637     }
 638
 639     return 0;
 640
 641 err:
 642     if (client->fd != -1) {
 643         close(client->fd);
 644         client->fd = -1;
 645     }
 646     return ret;
 647 }
 648
 649 static int coroutine_fn prh_read_request(PRHelperClient *client,
 650                                          PRHelperRequest *req,
 651                                          PRHelperResponse *resp, Error **errp)
 652 {
 653     uint32_t sz;
 654
 655     if (prh_read(client, req->cdb, sizeof(req->cdb), NULL) < 0) {
 656         return -1;
 657     }
 658
 659     if (client->fd == -1) {
 660         error_setg(errp, "No file descriptor in request.");
 661         return -1;
 662     }
 663
 664     if (req->cdb[0] != PERSISTENT_RESERVE_OUT &&
 665         req->cdb[0] != PERSISTENT_RESERVE_IN) {
 666         error_setg(errp, "Invalid CDB, closing socket.");
 667         goto out_close;
 668     }
 669
 670     sz = scsi_cdb_xfer(req->cdb);
 671     if (sz > sizeof(client->data)) {
 672         goto out_close;
 673     }
 674
 675     if (req->cdb[0] == PERSISTENT_RESERVE_OUT) {
 676         if (qio_channel_read_all(QIO_CHANNEL(client->ioc),
 677                                  (char *)client->data, sz,
 678                                  errp) < 0) {
 679             goto out_close;
 680         }
 681         if ((fcntl(client->fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {
 682             scsi_build_sense(resp->sense, SENSE_CODE(INVALID_OPCODE));
 683             sz = 0;
 684         } else if (sz < PR_OUT_FIXED_PARAM_SIZE) {
 685             /* Illegal request, Parameter list length error.  This isn't fatal;
 686              * we have read the data, send an error without closing the socket.
 687              */
 688             scsi_build_sense(resp->sense, SENSE_CODE(INVALID_PARAM_LEN));
 689             sz = 0;
 690         }
 691         if (sz == 0) {
 692             resp->result = CHECK_CONDITION;
 693             close(client->fd);
 694             client->fd = -1;
 695         }
 696     }
 697
 698     req->fd = client->fd;
 699     req->sz = sz;
 700     client->fd = -1;
 701     return sz;
 702
 703 out_close:
 704     close(client->fd);
 705     client->fd = -1;
 706     return -1;
 707 }
 708
 709 static int coroutine_fn prh_write_response(PRHelperClient *client,
 710                                            PRHelperRequest *req,
 711                                            PRHelperResponse *resp, Error **errp)
 712 {
 713     ssize_t r;
 714     size_t sz;
 715
 716     if (req->cdb[0] == PERSISTENT_RESERVE_IN && resp->result == GOOD) {
 717         assert(resp->sz <= req->sz && resp->sz <= sizeof(client->data));
 718     } else {
 719         assert(resp->sz == 0);
 720     }
 721
 722     sz = resp->sz;
 723
 724     resp->result = cpu_to_be32(resp->result);
 725     resp->sz = cpu_to_be32(resp->sz);
 726     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 727                               (char *) resp, sizeof(*resp), errp);
 728     if (r < 0) {
 729         return r;
 730     }
 731
 732     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 733                               (char *) client->data,
 734                               sz, errp);
 735     return r < 0 ? r : 0;
 736 }
 737
 738 static void coroutine_fn prh_co_entry(void *opaque)
 739 {
 740     PRHelperClient *client = opaque;
 741     Error *local_err = NULL;
 742     uint32_t flags;
 743     int r;
 744
 745     qio_channel_set_blocking(QIO_CHANNEL(client->ioc),
 746                              false, NULL);
 747     qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc),
 748                                    qemu_get_aio_context());
 749
 750     /* A very simple negotiation for future extensibility.  No features
 751      * are defined so write 0.
 752      */
 753     flags = cpu_to_be32(0);
 754     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 755                              (char *) &flags, sizeof(flags), NULL);
 756     if (r < 0) {
 757         goto out;
 758     }
 759
 760     r = qio_channel_read_all(QIO_CHANNEL(client->ioc),
 761                              (char *) &flags, sizeof(flags), NULL);
 762     if (be32_to_cpu(flags) != 0 || r < 0) {
 763         goto out;
 764     }
 765
 766     while (atomic_read(&state) == RUNNING) {
 767         PRHelperRequest req;
 768         PRHelperResponse resp;
 769         int sz;
 770
 771         sz = prh_read_request(client, &req, &resp, &local_err);
 772         if (sz < 0) {
 773             break;
 774         }
 775
 776         if (sz > 0) {
 777             num_active_sockets++;
 778             if (req.cdb[0] == PERSISTENT_RESERVE_OUT) {
 779                 r = do_pr_out(req.fd, req.cdb, resp.sense,
 780                               client->data, sz);
 781                 resp.sz = 0;
 782             } else {
 783                 resp.sz = sizeof(client->data);
 784                 r = do_pr_in(req.fd, req.cdb, resp.sense,
 785                              client->data, &resp.sz);
 786                 resp.sz = MIN(resp.sz, sz);
 787             }
 788             num_active_sockets--;
 789             close(req.fd);
 790             if (r == -1) {
 791                 break;
 792             }
 793             resp.result = r;
 794         }
 795
 796         if (prh_write_response(client, &req, &resp, &local_err) < 0) {
 797             break;
 798         }
 799     }
 800
 801     if (local_err) {
 802         if (verbose == 0) {
 803             error_free(local_err);
 804         } else {
 805             error_report_err(local_err);
 806         }
 807     }
 808
 809 out:
 810     qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
 811     object_unref(OBJECT(client->ioc));
 812     g_free(client);
 813 }
 814
 815 static gboolean accept_client(QIOChannel *ioc, GIOCondition cond, gpointer opaque)
 816 {
 817     QIOChannelSocket *cioc;
 818     PRHelperClient *prh;
 819
 820     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
 821                                      NULL);
 822     if (!cioc) {
 823         return TRUE;
 824     }
 825
 826     prh = g_new(PRHelperClient, 1);
 827     prh->ioc = cioc;
 828     prh->fd = -1;
 829     prh->co = qemu_coroutine_create(prh_co_entry, prh);
 830     qemu_coroutine_enter(prh->co);
 831
 832     return TRUE;
 833 }
 834
 835
 836 /*
 837  * Check socket parameters compatibility when socket activation is used.
 838  */
 839 static const char *socket_activation_validate_opts(void)
 840 {
 841     if (socket_path != NULL) {
 842         return "Unix socket can't be set when using socket activation";
 843     }
 844
 845     return NULL;
 846 }
 847
 848 static void compute_default_paths(void)
 849 {
 850     if (!socket_path) {
 851         socket_path = qemu_get_local_state_pathname("run/qemu-pr-helper.sock");
 852     }
 853 }
 854
 855 static void termsig_handler(int signum)
 856 {
 857     atomic_cmpxchg(&state, RUNNING, TERMINATE);
 858     qemu_notify_event();
 859 }
 860
 861 static void close_server_socket(void)
 862 {
 863     assert(server_ioc);
 864
 865     g_source_remove(server_watch);
 866     server_watch = -1;
 867     object_unref(OBJECT(server_ioc));
 868     num_active_sockets--;
 869 }
 870
 871 #ifdef CONFIG_LIBCAP
 872 static int drop_privileges(void)
 873 {
 874     /* clear all capabilities */
 875     capng_clear(CAPNG_SELECT_BOTH);
 876
 877     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 878                      CAP_SYS_RAWIO) < 0) {
 879         return -1;
 880     }
 881
 882 #ifdef CONFIG_MPATH
 883     /* For /dev/mapper/control ioctls */
 884     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 885                      CAP_SYS_ADMIN) < 0) {
 886         return -1;
 887     }
 888 #endif
 889
 890     /* Change user/group id, retaining the capabilities.  Because file descriptors
 891      * are passed via SCM_RIGHTS, we don't need supplementary groups (and in
 892      * fact the helper can run as "nobody").
 893      */
 894     if (capng_change_id(uid != -1 ? uid : getuid(),
 895                         gid != -1 ? gid : getgid(),
 896                         CAPNG_DROP_SUPP_GRP | CAPNG_CLEAR_BOUNDING)) {
 897         return -1;
 898     }
 899
 900     return 0;
 901 }
 902 #endif
 903
 904 int main(int argc, char **argv)
 905 {
 906     const char *sopt = "hVk:fdT:u:g:vq";
 907     struct option lopt[] = {
 908         { "help", no_argument, NULL, 'h' },
 909         { "version", no_argument, NULL, 'V' },
 910         { "socket", required_argument, NULL, 'k' },
 911         { "pidfile", no_argument, NULL, 'f' },
 912         { "daemon", no_argument, NULL, 'd' },
 913         { "trace", required_argument, NULL, 'T' },
 914         { "user", required_argument, NULL, 'u' },
 915         { "group", required_argument, NULL, 'g' },
 916         { "verbose", no_argument, NULL, 'v' },
 917         { "quiet", no_argument, NULL, 'q' },
 918         { NULL, 0, NULL, 0 }
 919     };
 920     int opt_ind = 0;
 921     int loglevel = 1;
 922     int quiet = 0;
 923     int ch;
 924     Error *local_err = NULL;
 925     char *trace_file = NULL;
 926     bool daemonize = false;
 927     unsigned socket_activation;
 928
 929     struct sigaction sa_sigterm;
 930     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 931     sa_sigterm.sa_handler = termsig_handler;
 932     sigaction(SIGTERM, &sa_sigterm, NULL);
 933     sigaction(SIGINT, &sa_sigterm, NULL);
 934     sigaction(SIGHUP, &sa_sigterm, NULL);
 935
 936     signal(SIGPIPE, SIG_IGN);
 937
 938     module_call_init(MODULE_INIT_TRACE);
 939     module_call_init(MODULE_INIT_QOM);
 940     qemu_add_opts(&qemu_trace_opts);
 941     qemu_init_exec_dir(argv[0]);
 942
 943     pidfile = qemu_get_local_state_pathname("run/qemu-pr-helper.pid");
 944
 945     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 946         switch (ch) {
 947         case 'k':
 948             socket_path = optarg;
 949             if (socket_path[0] != '/') {
 950                 error_report("socket path must be absolute");
 951                 exit(EXIT_FAILURE);
 952             }
 953             break;
 954         case 'f':
 955             pidfile = optarg;
 956             break;
 957 #ifdef CONFIG_LIBCAP
 958         case 'u': {
 959             unsigned long res;
 960             struct passwd *userinfo = getpwnam(optarg);
 961             if (userinfo) {
 962                 uid = userinfo->pw_uid;
 963             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 964                        (uid_t)res == res) {
 965                 uid = res;
 966             } else {
 967                 error_report("invalid user '%s'", optarg);
 968                 exit(EXIT_FAILURE);
 969             }
 970             break;
 971         }
 972         case 'g': {
 973             unsigned long res;
 974             struct group *groupinfo = getgrnam(optarg);
 975             if (groupinfo) {
 976                 gid = groupinfo->gr_gid;
 977             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 978                        (gid_t)res == res) {
 979                 gid = res;
 980             } else {
 981                 error_report("invalid group '%s'", optarg);
 982                 exit(EXIT_FAILURE);
 983             }
 984             break;
 985         }
 986 #else
 987         case 'u':
 988         case 'g':
 989             error_report("-%c not supported by this %s", ch, argv[0]);
 990             exit(1);
 991 #endif
 992         case 'd':
 993             daemonize = true;
 994             break;
 995         case 'q':
 996             quiet = 1;
 997             break;
 998         case 'v':
 999             ++loglevel;
1000             break;
1001         case 'T':
1002             g_free(trace_file);
1003             trace_file = trace_opt_parse(optarg);
1004             break;
1005         case 'V':
1006             version(argv[0]);
1007             exit(EXIT_SUCCESS);
1008             break;
1009         case 'h':
1010             usage(argv[0]);
1011             exit(EXIT_SUCCESS);
1012             break;
1013         case '?':
1014             error_report("Try `%s --help' for more information.", argv[0]);
1015             exit(EXIT_FAILURE);
1016         }
1017     }
1018
1019     /* set verbosity */
1020     noisy = !quiet && (loglevel >= 3);
1021     verbose = quiet ? 0 : MIN(loglevel, 3);
1022
1023     if (!trace_init_backends()) {
1024         exit(EXIT_FAILURE);
1025     }
1026     trace_init_file(trace_file);
1027     qemu_set_log(LOG_TRACE);
1028
1029 #ifdef CONFIG_MPATH
1030     dm_init();
1031     multipath_pr_init();
1032 #endif
1033
1034     socket_activation = check_socket_activation();
1035     if (socket_activation == 0) {
1036         SocketAddress saddr;
1037         compute_default_paths();
1038         saddr = (SocketAddress){
1039             .type = SOCKET_ADDRESS_TYPE_UNIX,
1040             .u.q_unix.path = g_strdup(socket_path)
1041         };
1042         server_ioc = qio_channel_socket_new();
1043         if (qio_channel_socket_listen_sync(server_ioc, &saddr, &local_err) < 0) {
1044             object_unref(OBJECT(server_ioc));
1045             error_report_err(local_err);
1046             return 1;
1047         }
1048         g_free(saddr.u.q_unix.path);
1049     } else {
1050         /* Using socket activation - check user didn't use -p etc. */
1051         const char *err_msg = socket_activation_validate_opts();
1052         if (err_msg != NULL) {
1053             error_report("%s", err_msg);
1054             exit(EXIT_FAILURE);
1055         }
1056
1057         /* Can only listen on a single socket.  */
1058         if (socket_activation > 1) {
1059             error_report("%s does not support socket activation with LISTEN_FDS > 1",
1060                          argv[0]);
1061             exit(EXIT_FAILURE);
1062         }
1063         server_ioc = qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_FD,
1064                                                &local_err);
1065         if (server_ioc == NULL) {
1066             error_report("Failed to use socket activation: %s",
1067                          error_get_pretty(local_err));
1068             exit(EXIT_FAILURE);
1069         }
1070         socket_path = NULL;
1071     }
1072
1073     if (qemu_init_main_loop(&local_err)) {
1074         error_report_err(local_err);
1075         exit(EXIT_FAILURE);
1076     }
1077
1078     server_watch = qio_channel_add_watch(QIO_CHANNEL(server_ioc),
1079                                          G_IO_IN,
1080                                          accept_client,
1081                                          NULL, NULL);
1082
1083 #ifdef CONFIG_LIBCAP
1084     if (drop_privileges() < 0) {
1085         error_report("Failed to drop privileges: %s", strerror(errno));
1086         exit(EXIT_FAILURE);
1087     }
1088 #endif
1089
1090     if (daemonize) {
1091         if (daemon(0, 0) < 0) {
1092             error_report("Failed to daemonize: %s", strerror(errno));
1093             exit(EXIT_FAILURE);
1094         }
1095         write_pidfile();
1096     }
1097
1098     state = RUNNING;
1099     do {
1100         main_loop_wait(false);
1101         if (state == TERMINATE) {
1102             state = TERMINATING;
1103             close_server_socket();
1104         }
1105     } while (num_active_sockets > 0);
1106
1107     exit(EXIT_SUCCESS);
1108 }