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_VERSION QEMU_PKGVERSION "\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 int mpath_reconstruct_sense(int fd, int r, uint8_t *sense)
 318 {
 319     switch (r) {
 320     case MPATH_PR_SUCCESS:
 321         return GOOD;
 322     case MPATH_PR_SENSE_NOT_READY:
 323     case MPATH_PR_SENSE_MEDIUM_ERROR:
 324     case MPATH_PR_SENSE_HARDWARE_ERROR:
 325     case MPATH_PR_SENSE_ABORTED_COMMAND:
 326         {
 327             /* libmpathpersist ate the exact sense.  Try to find it by
 328              * issuing TEST UNIT READY.
 329              */
 330             uint8_t cdb[6] = { TEST_UNIT_READY };
 331             int sz = 0;
 332             return do_sgio(fd, cdb, sense, NULL, &sz, SG_DXFER_NONE);
 333         }
 334
 335     case MPATH_PR_SENSE_UNIT_ATTENTION:
 336         /* Congratulations libmpathpersist, you ruined the Unit Attention...
 337          * Return a heavyweight one.
 338          */
 339         scsi_build_sense(sense, SENSE_CODE(SCSI_BUS_RESET));
 340         return CHECK_CONDITION;
 341     case MPATH_PR_SENSE_INVALID_OP:
 342         /* Only one valid sense.  */
 343         scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 344         return CHECK_CONDITION;
 345     case MPATH_PR_ILLEGAL_REQ:
 346         /* Guess.  */
 347         scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 348         return CHECK_CONDITION;
 349     case MPATH_PR_NO_SENSE:
 350         scsi_build_sense(sense, SENSE_CODE(NO_SENSE));
 351         return CHECK_CONDITION;
 352
 353     case MPATH_PR_RESERV_CONFLICT:
 354         return RESERVATION_CONFLICT;
 355
 356     case MPATH_PR_OTHER:
 357     default:
 358         scsi_build_sense(sense, SENSE_CODE(LUN_COMM_FAILURE));
 359         return CHECK_CONDITION;
 360     }
 361 }
 362
 363 static int multipath_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 364                            uint8_t *data, int sz)
 365 {
 366     int rq_servact = cdb[1];
 367     struct prin_resp resp;
 368     size_t written;
 369     int r;
 370
 371     switch (rq_servact) {
 372     case MPATH_PRIN_RKEY_SA:
 373     case MPATH_PRIN_RRES_SA:
 374     case MPATH_PRIN_RCAP_SA:
 375         break;
 376     case MPATH_PRIN_RFSTAT_SA:
 377         /* Nobody implements it anyway, so bail out. */
 378     default:
 379         /* Cannot parse any other output.  */
 380         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 381         return CHECK_CONDITION;
 382     }
 383
 384     r = mpath_persistent_reserve_in(fd, rq_servact, &resp, noisy, verbose);
 385     if (r == MPATH_PR_SUCCESS) {
 386         switch (rq_servact) {
 387         case MPATH_PRIN_RKEY_SA:
 388         case MPATH_PRIN_RRES_SA: {
 389             struct prin_readdescr *out = &resp.prin_descriptor.prin_readkeys;
 390             assert(sz >= 8);
 391             written = MIN(out->additional_length + 8, sz);
 392             stl_be_p(&data[0], out->prgeneration);
 393             stl_be_p(&data[4], out->additional_length);
 394             memcpy(&data[8], out->key_list, written - 8);
 395             break;
 396         }
 397         case MPATH_PRIN_RCAP_SA: {
 398             struct prin_capdescr *out = &resp.prin_descriptor.prin_readcap;
 399             assert(sz >= 6);
 400             written = 6;
 401             stw_be_p(&data[0], out->length);
 402             data[2] = out->flags[0];
 403             data[3] = out->flags[1];
 404             stw_be_p(&data[4], out->pr_type_mask);
 405             break;
 406         }
 407         default:
 408             scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 409             return CHECK_CONDITION;
 410         }
 411         assert(written <= sz);
 412         memset(data + written, 0, sz - written);
 413     }
 414
 415     return mpath_reconstruct_sense(fd, r, sense);
 416 }
 417
 418 static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 419                             const uint8_t *param, int sz)
 420 {
 421     int rq_servact = cdb[1];
 422     int rq_scope = cdb[2] >> 4;
 423     int rq_type = cdb[2] & 0xf;
 424     struct prout_param_descriptor paramp;
 425     char transportids[PR_HELPER_DATA_SIZE];
 426     int r;
 427
 428     switch (rq_servact) {
 429     case MPATH_PROUT_REG_SA:
 430     case MPATH_PROUT_RES_SA:
 431     case MPATH_PROUT_REL_SA:
 432     case MPATH_PROUT_CLEAR_SA:
 433     case MPATH_PROUT_PREE_SA:
 434     case MPATH_PROUT_PREE_AB_SA:
 435     case MPATH_PROUT_REG_IGN_SA:
 436         break;
 437     case MPATH_PROUT_REG_MOV_SA:
 438         /* Not supported by struct prout_param_descriptor.  */
 439     default:
 440         /* Cannot parse any other input.  */
 441         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 442         return CHECK_CONDITION;
 443     }
 444
 445     /* Convert input data, especially transport IDs, to the structs
 446      * used by libmpathpersist (which, of course, will immediately
 447      * do the opposite).
 448      */
 449     memset(&paramp, 0, sizeof(paramp));
 450     memcpy(&paramp.key, &param[0], 8);
 451     memcpy(&paramp.sa_key, &param[8], 8);
 452     paramp.sa_flags = param[10];
 453     if (sz > PR_OUT_FIXED_PARAM_SIZE) {
 454         size_t transportid_len;
 455         int i, j;
 456         if (sz < PR_OUT_FIXED_PARAM_SIZE + 4) {
 457             scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM_LEN));
 458             return CHECK_CONDITION;
 459         }
 460         transportid_len = ldl_be_p(&param[24]) + PR_OUT_FIXED_PARAM_SIZE + 4;
 461         if (transportid_len > sz) {
 462             scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 463             return CHECK_CONDITION;
 464         }
 465         for (i = PR_OUT_FIXED_PARAM_SIZE + 4, j = 0; i < transportid_len; ) {
 466             struct transportid *id = (struct transportid *) &transportids[j];
 467             int len;
 468
 469             id->format_code = param[i] & 0xc0;
 470             id->protocol_id = param[i] & 0x0f;
 471             switch (param[i] & 0xcf) {
 472             case 0:
 473                 /* FC transport.  */
 474                 if (i + 24 > transportid_len) {
 475                     goto illegal_req;
 476                 }
 477                 memcpy(id->n_port_name, &param[i + 8], 8);
 478                 j += offsetof(struct transportid, n_port_name[8]);
 479                 i += 24;
 480                 break;
 481             case 3:
 482             case 0x43:
 483                 /* iSCSI transport.  */
 484                 len = lduw_be_p(&param[i + 2]);
 485                 if (len > 252 || (len & 3) || i + len + 4 > transportid_len) {
 486                     /* For format code 00, the standard says the maximum is 223
 487                      * plus the NUL terminator.  For format code 01 there is no
 488                      * maximum length, but libmpathpersist ignores the first
 489                      * byte of id->iscsi_name so our maximum is 252.
 490                      */
 491                     goto illegal_req;
 492                 }
 493                 if (memchr(&param[i + 4], 0, len) == NULL) {
 494                     goto illegal_req;
 495                 }
 496                 memcpy(id->iscsi_name, &param[i + 2], len + 2);
 497                 j += offsetof(struct transportid, iscsi_name[len + 2]);
 498                 i += len + 4;
 499                 break;
 500             case 6:
 501                 /* SAS transport.  */
 502                 if (i + 24 > transportid_len) {
 503                     goto illegal_req;
 504                 }
 505                 memcpy(id->sas_address, &param[i + 4], 8);
 506                 j += offsetof(struct transportid, sas_address[8]);
 507                 i += 24;
 508                 break;
 509             default:
 510             illegal_req:
 511                 scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 512                 return CHECK_CONDITION;
 513             }
 514
 515             paramp.trnptid_list[paramp.num_transportid++] = id;
 516         }
 517     }
 518
 519     r = mpath_persistent_reserve_out(fd, rq_servact, rq_scope, rq_type,
 520                                      &paramp, noisy, verbose);
 521     return mpath_reconstruct_sense(fd, r, sense);
 522 }
 523 #endif
 524
 525 static int do_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 526                     uint8_t *data, int *resp_sz)
 527 {
 528 #ifdef CONFIG_MPATH
 529     if (is_mpath(fd)) {
 530         /* multipath_pr_in fills the whole input buffer.  */
 531         return multipath_pr_in(fd, cdb, sense, data, *resp_sz);
 532     }
 533 #endif
 534
 535     return do_sgio(fd, cdb, sense, data, resp_sz,
 536                    SG_DXFER_FROM_DEV);
 537 }
 538
 539 static int do_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 540                      const uint8_t *param, int sz)
 541 {
 542     int resp_sz;
 543 #ifdef CONFIG_MPATH
 544     if (is_mpath(fd)) {
 545         return multipath_pr_out(fd, cdb, sense, param, sz);
 546     }
 547 #endif
 548
 549     resp_sz = sz;
 550     return do_sgio(fd, cdb, sense, (uint8_t *)param, &resp_sz,
 551                    SG_DXFER_TO_DEV);
 552 }
 553
 554 /* Client */
 555
 556 typedef struct PRHelperClient {
 557     QIOChannelSocket *ioc;
 558     Coroutine *co;
 559     int fd;
 560     uint8_t data[PR_HELPER_DATA_SIZE];
 561 } PRHelperClient;
 562
 563 typedef struct PRHelperRequest {
 564     int fd;
 565     size_t sz;
 566     uint8_t cdb[PR_HELPER_CDB_SIZE];
 567 } PRHelperRequest;
 568
 569 static int coroutine_fn prh_read(PRHelperClient *client, void *buf, int sz,
 570                                  Error **errp)
 571 {
 572     int ret = 0;
 573
 574     while (sz > 0) {
 575         int *fds = NULL;
 576         size_t nfds = 0;
 577         int i;
 578         struct iovec iov;
 579         ssize_t n_read;
 580
 581         iov.iov_base = buf;
 582         iov.iov_len = sz;
 583         n_read = qio_channel_readv_full(QIO_CHANNEL(client->ioc), &iov, 1,
 584                                         &fds, &nfds, errp);
 585
 586         if (n_read == QIO_CHANNEL_ERR_BLOCK) {
 587             qio_channel_yield(QIO_CHANNEL(client->ioc), G_IO_IN);
 588             continue;
 589         }
 590         if (n_read <= 0) {
 591             ret = n_read ? n_read : -1;
 592             goto err;
 593         }
 594
 595         /* Stash one file descriptor per request.  */
 596         if (nfds) {
 597             bool too_many = false;
 598             for (i = 0; i < nfds; i++) {
 599                 if (client->fd == -1) {
 600                     client->fd = fds[i];
 601                 } else {
 602                     close(fds[i]);
 603                     too_many = true;
 604                 }
 605             }
 606             g_free(fds);
 607             if (too_many) {
 608                 ret = -1;
 609                 goto err;
 610             }
 611         }
 612
 613         buf += n_read;
 614         sz -= n_read;
 615     }
 616
 617     return 0;
 618
 619 err:
 620     if (client->fd != -1) {
 621         close(client->fd);
 622         client->fd = -1;
 623     }
 624     return ret;
 625 }
 626
 627 static int coroutine_fn prh_read_request(PRHelperClient *client,
 628                                          PRHelperRequest *req,
 629                                          PRHelperResponse *resp, Error **errp)
 630 {
 631     uint32_t sz;
 632
 633     if (prh_read(client, req->cdb, sizeof(req->cdb), NULL) < 0) {
 634         return -1;
 635     }
 636
 637     if (client->fd == -1) {
 638         error_setg(errp, "No file descriptor in request.");
 639         return -1;
 640     }
 641
 642     if (req->cdb[0] != PERSISTENT_RESERVE_OUT &&
 643         req->cdb[0] != PERSISTENT_RESERVE_IN) {
 644         error_setg(errp, "Invalid CDB, closing socket.");
 645         goto out_close;
 646     }
 647
 648     sz = scsi_cdb_xfer(req->cdb);
 649     if (sz > sizeof(client->data)) {
 650         goto out_close;
 651     }
 652
 653     if (req->cdb[0] == PERSISTENT_RESERVE_OUT) {
 654         if (qio_channel_read_all(QIO_CHANNEL(client->ioc),
 655                                  (char *)client->data, sz,
 656                                  errp) < 0) {
 657             goto out_close;
 658         }
 659         if ((fcntl(client->fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {
 660             scsi_build_sense(resp->sense, SENSE_CODE(INVALID_OPCODE));
 661             sz = 0;
 662         } else if (sz < PR_OUT_FIXED_PARAM_SIZE) {
 663             /* Illegal request, Parameter list length error.  This isn't fatal;
 664              * we have read the data, send an error without closing the socket.
 665              */
 666             scsi_build_sense(resp->sense, SENSE_CODE(INVALID_PARAM_LEN));
 667             sz = 0;
 668         }
 669         if (sz == 0) {
 670             resp->result = CHECK_CONDITION;
 671             close(client->fd);
 672             client->fd = -1;
 673         }
 674     }
 675
 676     req->fd = client->fd;
 677     req->sz = sz;
 678     client->fd = -1;
 679     return sz;
 680
 681 out_close:
 682     close(client->fd);
 683     client->fd = -1;
 684     return -1;
 685 }
 686
 687 static int coroutine_fn prh_write_response(PRHelperClient *client,
 688                                            PRHelperRequest *req,
 689                                            PRHelperResponse *resp, Error **errp)
 690 {
 691     ssize_t r;
 692     size_t sz;
 693
 694     if (req->cdb[0] == PERSISTENT_RESERVE_IN && resp->result == GOOD) {
 695         assert(resp->sz <= req->sz && resp->sz <= sizeof(client->data));
 696     } else {
 697         assert(resp->sz == 0);
 698     }
 699
 700     sz = resp->sz;
 701
 702     resp->result = cpu_to_be32(resp->result);
 703     resp->sz = cpu_to_be32(resp->sz);
 704     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 705                               (char *) resp, sizeof(*resp), errp);
 706     if (r < 0) {
 707         return r;
 708     }
 709
 710     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 711                               (char *) client->data,
 712                               sz, errp);
 713     return r < 0 ? r : 0;
 714 }
 715
 716 static void coroutine_fn prh_co_entry(void *opaque)
 717 {
 718     PRHelperClient *client = opaque;
 719     Error *local_err = NULL;
 720     uint32_t flags;
 721     int r;
 722
 723     qio_channel_set_blocking(QIO_CHANNEL(client->ioc),
 724                              false, NULL);
 725     qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc),
 726                                    qemu_get_aio_context());
 727
 728     /* A very simple negotiation for future extensibility.  No features
 729      * are defined so write 0.
 730      */
 731     flags = cpu_to_be32(0);
 732     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 733                              (char *) &flags, sizeof(flags), NULL);
 734     if (r < 0) {
 735         goto out;
 736     }
 737
 738     r = qio_channel_read_all(QIO_CHANNEL(client->ioc),
 739                              (char *) &flags, sizeof(flags), NULL);
 740     if (be32_to_cpu(flags) != 0 || r < 0) {
 741         goto out;
 742     }
 743
 744     while (atomic_read(&state) == RUNNING) {
 745         PRHelperRequest req;
 746         PRHelperResponse resp;
 747         int sz;
 748
 749         sz = prh_read_request(client, &req, &resp, &local_err);
 750         if (sz < 0) {
 751             break;
 752         }
 753
 754         if (sz > 0) {
 755             num_active_sockets++;
 756             if (req.cdb[0] == PERSISTENT_RESERVE_OUT) {
 757                 r = do_pr_out(req.fd, req.cdb, resp.sense,
 758                               client->data, sz);
 759                 resp.sz = 0;
 760             } else {
 761                 resp.sz = sizeof(client->data);
 762                 r = do_pr_in(req.fd, req.cdb, resp.sense,
 763                              client->data, &resp.sz);
 764                 resp.sz = MIN(resp.sz, sz);
 765             }
 766             num_active_sockets--;
 767             close(req.fd);
 768             if (r == -1) {
 769                 break;
 770             }
 771             resp.result = r;
 772         }
 773
 774         if (prh_write_response(client, &req, &resp, &local_err) < 0) {
 775             break;
 776         }
 777     }
 778
 779     if (local_err) {
 780         if (verbose == 0) {
 781             error_free(local_err);
 782         } else {
 783             error_report_err(local_err);
 784         }
 785     }
 786
 787 out:
 788     qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
 789     object_unref(OBJECT(client->ioc));
 790     g_free(client);
 791 }
 792
 793 static gboolean accept_client(QIOChannel *ioc, GIOCondition cond, gpointer opaque)
 794 {
 795     QIOChannelSocket *cioc;
 796     PRHelperClient *prh;
 797
 798     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
 799                                      NULL);
 800     if (!cioc) {
 801         return TRUE;
 802     }
 803
 804     prh = g_new(PRHelperClient, 1);
 805     prh->ioc = cioc;
 806     prh->fd = -1;
 807     prh->co = qemu_coroutine_create(prh_co_entry, prh);
 808     qemu_coroutine_enter(prh->co);
 809
 810     return TRUE;
 811 }
 812
 813
 814 /*
 815  * Check socket parameters compatibility when socket activation is used.
 816  */
 817 static const char *socket_activation_validate_opts(void)
 818 {
 819     if (socket_path != NULL) {
 820         return "Unix socket can't be set when using socket activation";
 821     }
 822
 823     return NULL;
 824 }
 825
 826 static void compute_default_paths(void)
 827 {
 828     if (!socket_path) {
 829         socket_path = qemu_get_local_state_pathname("run/qemu-pr-helper.sock");
 830     }
 831 }
 832
 833 static void termsig_handler(int signum)
 834 {
 835     atomic_cmpxchg(&state, RUNNING, TERMINATE);
 836     qemu_notify_event();
 837 }
 838
 839 static void close_server_socket(void)
 840 {
 841     assert(server_ioc);
 842
 843     g_source_remove(server_watch);
 844     server_watch = -1;
 845     object_unref(OBJECT(server_ioc));
 846     num_active_sockets--;
 847 }
 848
 849 #ifdef CONFIG_LIBCAP
 850 static int drop_privileges(void)
 851 {
 852     /* clear all capabilities */
 853     capng_clear(CAPNG_SELECT_BOTH);
 854
 855     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 856                      CAP_SYS_RAWIO) < 0) {
 857         return -1;
 858     }
 859
 860 #ifdef CONFIG_MPATH
 861     /* For /dev/mapper/control ioctls */
 862     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 863                      CAP_SYS_ADMIN) < 0) {
 864         return -1;
 865     }
 866 #endif
 867
 868     /* Change user/group id, retaining the capabilities.  Because file descriptors
 869      * are passed via SCM_RIGHTS, we don't need supplementary groups (and in
 870      * fact the helper can run as "nobody").
 871      */
 872     if (capng_change_id(uid != -1 ? uid : getuid(),
 873                         gid != -1 ? gid : getgid(),
 874                         CAPNG_DROP_SUPP_GRP | CAPNG_CLEAR_BOUNDING)) {
 875         return -1;
 876     }
 877
 878     return 0;
 879 }
 880 #endif
 881
 882 int main(int argc, char **argv)
 883 {
 884     const char *sopt = "hVk:fdT:u:g:vq";
 885     struct option lopt[] = {
 886         { "help", no_argument, NULL, 'h' },
 887         { "version", no_argument, NULL, 'V' },
 888         { "socket", required_argument, NULL, 'k' },
 889         { "pidfile", no_argument, NULL, 'f' },
 890         { "daemon", no_argument, NULL, 'd' },
 891         { "trace", required_argument, NULL, 'T' },
 892         { "user", required_argument, NULL, 'u' },
 893         { "group", required_argument, NULL, 'g' },
 894         { "verbose", no_argument, NULL, 'v' },
 895         { "quiet", no_argument, NULL, 'q' },
 896         { NULL, 0, NULL, 0 }
 897     };
 898     int opt_ind = 0;
 899     int loglevel = 1;
 900     int quiet = 0;
 901     int ch;
 902     Error *local_err = NULL;
 903     char *trace_file = NULL;
 904     bool daemonize = false;
 905     unsigned socket_activation;
 906
 907     struct sigaction sa_sigterm;
 908     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 909     sa_sigterm.sa_handler = termsig_handler;
 910     sigaction(SIGTERM, &sa_sigterm, NULL);
 911     sigaction(SIGINT, &sa_sigterm, NULL);
 912     sigaction(SIGHUP, &sa_sigterm, NULL);
 913
 914     signal(SIGPIPE, SIG_IGN);
 915
 916     module_call_init(MODULE_INIT_TRACE);
 917     module_call_init(MODULE_INIT_QOM);
 918     qemu_add_opts(&qemu_trace_opts);
 919     qemu_init_exec_dir(argv[0]);
 920
 921     pidfile = qemu_get_local_state_pathname("run/qemu-pr-helper.pid");
 922
 923     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 924         switch (ch) {
 925         case 'k':
 926             socket_path = optarg;
 927             if (socket_path[0] != '/') {
 928                 error_report("socket path must be absolute");
 929                 exit(EXIT_FAILURE);
 930             }
 931             break;
 932         case 'f':
 933             pidfile = optarg;
 934             break;
 935 #ifdef CONFIG_LIBCAP
 936         case 'u': {
 937             unsigned long res;
 938             struct passwd *userinfo = getpwnam(optarg);
 939             if (userinfo) {
 940                 uid = userinfo->pw_uid;
 941             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 942                        (uid_t)res == res) {
 943                 uid = res;
 944             } else {
 945                 error_report("invalid user '%s'", optarg);
 946                 exit(EXIT_FAILURE);
 947             }
 948             break;
 949         }
 950         case 'g': {
 951             unsigned long res;
 952             struct group *groupinfo = getgrnam(optarg);
 953             if (groupinfo) {
 954                 gid = groupinfo->gr_gid;
 955             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 956                        (gid_t)res == res) {
 957                 gid = res;
 958             } else {
 959                 error_report("invalid group '%s'", optarg);
 960                 exit(EXIT_FAILURE);
 961             }
 962             break;
 963         }
 964 #else
 965         case 'u':
 966         case 'g':
 967             error_report("-%c not supported by this %s", ch, argv[0]);
 968             exit(1);
 969 #endif
 970         case 'd':
 971             daemonize = true;
 972             break;
 973         case 'q':
 974             quiet = 1;
 975             break;
 976         case 'v':
 977             ++loglevel;
 978             break;
 979         case 'T':
 980             g_free(trace_file);
 981             trace_file = trace_opt_parse(optarg);
 982             break;
 983         case 'V':
 984             version(argv[0]);
 985             exit(EXIT_SUCCESS);
 986             break;
 987         case 'h':
 988             usage(argv[0]);
 989             exit(EXIT_SUCCESS);
 990             break;
 991         case '?':
 992             error_report("Try `%s --help' for more information.", argv[0]);
 993             exit(EXIT_FAILURE);
 994         }
 995     }
 996
 997     /* set verbosity */
 998     noisy = !quiet && (loglevel >= 3);
 999     verbose = quiet ? 0 : MIN(loglevel, 3);
1000
1001     if (!trace_init_backends()) {
1002         exit(EXIT_FAILURE);
1003     }
1004     trace_init_file(trace_file);
1005     qemu_set_log(LOG_TRACE);
1006
1007 #ifdef CONFIG_MPATH
1008     dm_init();
1009     multipath_pr_init();
1010 #endif
1011
1012     socket_activation = check_socket_activation();
1013     if (socket_activation == 0) {
1014         SocketAddress saddr;
1015         compute_default_paths();
1016         saddr = (SocketAddress){
1017             .type = SOCKET_ADDRESS_TYPE_UNIX,
1018             .u.q_unix.path = g_strdup(socket_path)
1019         };
1020         server_ioc = qio_channel_socket_new();
1021         if (qio_channel_socket_listen_sync(server_ioc, &saddr, &local_err) < 0) {
1022             object_unref(OBJECT(server_ioc));
1023             error_report_err(local_err);
1024             return 1;
1025         }
1026         g_free(saddr.u.q_unix.path);
1027     } else {
1028         /* Using socket activation - check user didn't use -p etc. */
1029         const char *err_msg = socket_activation_validate_opts();
1030         if (err_msg != NULL) {
1031             error_report("%s", err_msg);
1032             exit(EXIT_FAILURE);
1033         }
1034
1035         /* Can only listen on a single socket.  */
1036         if (socket_activation > 1) {
1037             error_report("%s does not support socket activation with LISTEN_FDS > 1",
1038                          argv[0]);
1039             exit(EXIT_FAILURE);
1040         }
1041         server_ioc = qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_FD,
1042                                                &local_err);
1043         if (server_ioc == NULL) {
1044             error_report("Failed to use socket activation: %s",
1045                          error_get_pretty(local_err));
1046             exit(EXIT_FAILURE);
1047         }
1048         socket_path = NULL;
1049     }
1050
1051     if (qemu_init_main_loop(&local_err)) {
1052         error_report_err(local_err);
1053         exit(EXIT_FAILURE);
1054     }
1055
1056     server_watch = qio_channel_add_watch(QIO_CHANNEL(server_ioc),
1057                                          G_IO_IN,
1058                                          accept_client,
1059                                          NULL, NULL);
1060
1061 #ifdef CONFIG_LIBCAP
1062     if (drop_privileges() < 0) {
1063         error_report("Failed to drop privileges: %s", strerror(errno));
1064         exit(EXIT_FAILURE);
1065     }
1066 #endif
1067
1068     if (daemonize) {
1069         if (daemon(0, 0) < 0) {
1070             error_report("Failed to daemonize: %s", strerror(errno));
1071             exit(EXIT_FAILURE);
1072         }
1073         write_pidfile();
1074     }
1075
1076     state = RUNNING;
1077     do {
1078         main_loop_wait(false);
1079         if (state == TERMINATE) {
1080             state = TERMINATING;
1081             close_server_socket();
1082         }
1083     } while (num_active_sockets > 0);
1084
1085     exit(EXIT_SUCCESS);
1086 }