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_NG
  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 "qemu/help-texts.h"
  40 #include "qapi/error.h"
  41 #include "qemu/cutils.h"
  42 #include "qemu/main-loop.h"
  43 #include "qemu/module.h"
  44 #include "qemu/error-report.h"
  45 #include "qemu/config-file.h"
  46 #include "qemu/bswap.h"
  47 #include "qemu/log.h"
  48 #include "qemu/systemd.h"
  49 #include "qapi/util.h"
  50 #include "qapi/qmp/qstring.h"
  51 #include "io/channel-socket.h"
  52 #include "trace/control.h"
  53 #include "qemu-version.h"
  54
  55 #include "block/aio.h"
  56 #include "block/thread-pool.h"
  57
  58 #include "scsi/constants.h"
  59 #include "scsi/utils.h"
  60 #include "pr-helper.h"
  61
  62 #define PR_OUT_FIXED_PARAM_SIZE 24
  63
  64 static char *socket_path;
  65 static char *pidfile;
  66 static enum { RUNNING, TERMINATE, TERMINATING } state;
  67 static QIOChannelSocket *server_ioc;
  68 static int server_watch;
  69 static int num_active_sockets = 1;
  70 static int noisy;
  71 static int verbose;
  72
  73 #ifdef CONFIG_LIBCAP_NG
  74 static int uid = -1;
  75 static int gid = -1;
  76 #endif
  77
  78 static void compute_default_paths(void)
  79 {
  80     g_autofree char *state = qemu_get_local_state_dir();
  81
  82     socket_path = g_build_filename(state, "run", "qemu-pr-helper.sock", NULL);
  83     pidfile = g_build_filename(state, "run", "qemu-pr-helper.pid", NULL);
  84 }
  85
  86 static void usage(const char *name)
  87 {
  88     (printf) (
  89 "Usage: %s [OPTIONS] FILE\n"
  90 "Persistent Reservation helper program for QEMU\n"
  91 "\n"
  92 "  -h, --help                display this help and exit\n"
  93 "  -V, --version             output version information and exit\n"
  94 "\n"
  95 "  -d, --daemon              run in the background\n"
  96 "  -f, --pidfile=PATH        PID file when running as a daemon\n"
  97 "                            (default '%s')\n"
  98 "  -k, --socket=PATH         path to the unix socket\n"
  99 "                            (default '%s')\n"
 100 "  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
 101 "                            specify tracing options\n"
 102 #ifdef CONFIG_LIBCAP_NG
 103 "  -u, --user=USER           user to drop privileges to\n"
 104 "  -g, --group=GROUP         group to drop privileges to\n"
 105 #endif
 106 "\n"
 107 QEMU_HELP_BOTTOM "\n"
 108     , name, pidfile, socket_path);
 109 }
 110
 111 static void version(const char *name)
 112 {
 113     printf(
 114 "%s " QEMU_FULL_VERSION "\n"
 115 "Written by Paolo Bonzini.\n"
 116 "\n"
 117 QEMU_COPYRIGHT "\n"
 118 "This is free software; see the source for copying conditions.  There is NO\n"
 119 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 120     , name);
 121 }
 122
 123 /* SG_IO support */
 124
 125 typedef struct PRHelperSGIOData {
 126     int fd;
 127     const uint8_t *cdb;
 128     uint8_t *sense;
 129     uint8_t *buf;
 130     int sz;              /* input/output */
 131     int dir;
 132 } PRHelperSGIOData;
 133
 134 static int do_sgio_worker(void *opaque)
 135 {
 136     PRHelperSGIOData *data = opaque;
 137     struct sg_io_hdr io_hdr;
 138     int ret;
 139     int status;
 140     SCSISense sense_code;
 141
 142     memset(data->sense, 0, PR_HELPER_SENSE_SIZE);
 143     memset(&io_hdr, 0, sizeof(io_hdr));
 144     io_hdr.interface_id = 'S';
 145     io_hdr.cmd_len = PR_HELPER_CDB_SIZE;
 146     io_hdr.cmdp = (uint8_t *)data->cdb;
 147     io_hdr.sbp = data->sense;
 148     io_hdr.mx_sb_len = PR_HELPER_SENSE_SIZE;
 149     io_hdr.timeout = 1;
 150     io_hdr.dxfer_direction = data->dir;
 151     io_hdr.dxferp = (char *)data->buf;
 152     io_hdr.dxfer_len = data->sz;
 153     ret = ioctl(data->fd, SG_IO, &io_hdr);
 154
 155     if (ret < 0) {
 156         status = scsi_sense_from_errno(errno, &sense_code);
 157         if (status == CHECK_CONDITION) {
 158             scsi_build_sense(data->sense, sense_code);
 159         }
 160     } else if (io_hdr.host_status != SCSI_HOST_OK) {
 161         status = scsi_sense_from_host_status(io_hdr.host_status, &sense_code);
 162         if (status == CHECK_CONDITION) {
 163             scsi_build_sense(data->sense, sense_code);
 164         }
 165     } else if (io_hdr.driver_status & SG_ERR_DRIVER_TIMEOUT) {
 166         status = BUSY;
 167     } else {
 168         status = io_hdr.status;
 169     }
 170
 171     if (status == GOOD) {
 172         data->sz -= io_hdr.resid;
 173     } else {
 174         data->sz = 0;
 175     }
 176
 177     return status;
 178 }
 179
 180 static int do_sgio(int fd, const uint8_t *cdb, uint8_t *sense,
 181                     uint8_t *buf, int *sz, int dir)
 182 {
 183     ThreadPool *pool = aio_get_thread_pool(qemu_get_aio_context());
 184     int r;
 185
 186     PRHelperSGIOData data = {
 187         .fd = fd,
 188         .cdb = cdb,
 189         .sense = sense,
 190         .buf = buf,
 191         .sz = *sz,
 192         .dir = dir,
 193     };
 194
 195     r = thread_pool_submit_co(pool, do_sgio_worker, &data);
 196     *sz = data.sz;
 197     return r;
 198 }
 199
 200 /* Device mapper interface */
 201
 202 #ifdef CONFIG_MPATH
 203 #define CONTROL_PATH "/dev/mapper/control"
 204
 205 typedef struct DMData {
 206     struct dm_ioctl dm;
 207     uint8_t data[1024];
 208 } DMData;
 209
 210 static int control_fd;
 211
 212 static void *dm_ioctl(int ioc, struct dm_ioctl *dm)
 213 {
 214     static DMData d;
 215     memcpy(&d.dm, dm, sizeof(d.dm));
 216     QEMU_BUILD_BUG_ON(sizeof(d.data) < sizeof(struct dm_target_spec));
 217
 218     d.dm.version[0] = DM_VERSION_MAJOR;
 219     d.dm.version[1] = 0;
 220     d.dm.version[2] = 0;
 221     d.dm.data_size = 1024;
 222     d.dm.data_start = offsetof(DMData, data);
 223     if (ioctl(control_fd, ioc, &d) < 0) {
 224         return NULL;
 225     }
 226     memcpy(dm, &d.dm, sizeof(d.dm));
 227     return &d.data;
 228 }
 229
 230 static void *dm_dev_ioctl(int fd, int ioc, struct dm_ioctl *dm)
 231 {
 232     struct stat st;
 233     int r;
 234
 235     r = fstat(fd, &st);
 236     if (r < 0) {
 237         perror("fstat");
 238         exit(1);
 239     }
 240
 241     dm->dev = st.st_rdev;
 242     return dm_ioctl(ioc, dm);
 243 }
 244
 245 static void dm_init(void)
 246 {
 247     control_fd = open(CONTROL_PATH, O_RDWR);
 248     if (control_fd < 0) {
 249         perror("Cannot open " CONTROL_PATH);
 250         exit(1);
 251     }
 252     struct dm_ioctl dm = { };
 253     if (!dm_ioctl(DM_VERSION, &dm)) {
 254         perror("ioctl");
 255         exit(1);
 256     }
 257     if (dm.version[0] != DM_VERSION_MAJOR) {
 258         fprintf(stderr, "Unsupported device mapper interface");
 259         exit(1);
 260     }
 261 }
 262
 263 /* Variables required by libmultipath and libmpathpersist.  */
 264 QEMU_BUILD_BUG_ON(PR_HELPER_DATA_SIZE > MPATH_MAX_PARAM_LEN);
 265 static struct config *multipath_conf;
 266 unsigned mpath_mx_alloc_len = PR_HELPER_DATA_SIZE;
 267 int logsink;
 268 struct udev *udev;
 269
 270 extern struct config *get_multipath_config(void);
 271 struct config *get_multipath_config(void)
 272 {
 273     return multipath_conf;
 274 }
 275
 276 extern void put_multipath_config(struct config *conf);
 277 void put_multipath_config(struct config *conf)
 278 {
 279 }
 280
 281 static void multipath_pr_init(void)
 282 {
 283     udev = udev_new();
 284 #ifdef CONFIG_MPATH_NEW_API
 285     multipath_conf = mpath_lib_init();
 286 #else
 287     mpath_lib_init(udev);
 288 #endif
 289 }
 290
 291 static int is_mpath(int fd)
 292 {
 293     struct dm_ioctl dm = { .flags = DM_NOFLUSH_FLAG };
 294     struct dm_target_spec *tgt;
 295
 296     tgt = dm_dev_ioctl(fd, DM_TABLE_STATUS, &dm);
 297     if (!tgt) {
 298         if (errno == ENXIO) {
 299             return 0;
 300         }
 301         perror("ioctl");
 302         exit(EXIT_FAILURE);
 303     }
 304     return !strncmp(tgt->target_type, "multipath", DM_MAX_TYPE_NAME);
 305 }
 306
 307 static SCSISense mpath_generic_sense(int r)
 308 {
 309     switch (r) {
 310     case MPATH_PR_SENSE_NOT_READY:
 311          return SENSE_CODE(NOT_READY);
 312     case MPATH_PR_SENSE_MEDIUM_ERROR:
 313          return SENSE_CODE(READ_ERROR);
 314     case MPATH_PR_SENSE_HARDWARE_ERROR:
 315          return SENSE_CODE(TARGET_FAILURE);
 316     case MPATH_PR_SENSE_ABORTED_COMMAND:
 317          return SENSE_CODE(IO_ERROR);
 318     default:
 319          abort();
 320     }
 321 }
 322
 323 static int mpath_reconstruct_sense(int fd, int r, uint8_t *sense)
 324 {
 325     switch (r) {
 326     case MPATH_PR_SUCCESS:
 327         return GOOD;
 328     case MPATH_PR_SENSE_NOT_READY:
 329     case MPATH_PR_SENSE_MEDIUM_ERROR:
 330     case MPATH_PR_SENSE_HARDWARE_ERROR:
 331     case MPATH_PR_SENSE_ABORTED_COMMAND:
 332         {
 333             /* libmpathpersist ate the exact sense.  Try to find it by
 334              * issuing TEST UNIT READY.
 335              */
 336             uint8_t cdb[6] = { TEST_UNIT_READY };
 337             int sz = 0;
 338             int ret = do_sgio(fd, cdb, sense, NULL, &sz, SG_DXFER_NONE);
 339
 340             if (ret != GOOD) {
 341                 return ret;
 342             }
 343             scsi_build_sense(sense, mpath_generic_sense(r));
 344             return CHECK_CONDITION;
 345         }
 346
 347     case MPATH_PR_SENSE_UNIT_ATTENTION:
 348         /* Congratulations libmpathpersist, you ruined the Unit Attention...
 349          * Return a heavyweight one.
 350          */
 351         scsi_build_sense(sense, SENSE_CODE(SCSI_BUS_RESET));
 352         return CHECK_CONDITION;
 353     case MPATH_PR_SENSE_INVALID_OP:
 354         /* Only one valid sense.  */
 355         scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 356         return CHECK_CONDITION;
 357     case MPATH_PR_ILLEGAL_REQ:
 358         /* Guess.  */
 359         scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));
 360         return CHECK_CONDITION;
 361     case MPATH_PR_NO_SENSE:
 362         scsi_build_sense(sense, SENSE_CODE(NO_SENSE));
 363         return CHECK_CONDITION;
 364
 365     case MPATH_PR_RESERV_CONFLICT:
 366         return RESERVATION_CONFLICT;
 367
 368     case MPATH_PR_OTHER:
 369     default:
 370         scsi_build_sense(sense, SENSE_CODE(LUN_COMM_FAILURE));
 371         return CHECK_CONDITION;
 372     }
 373 }
 374
 375 static int multipath_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 376                            uint8_t *data, int sz)
 377 {
 378     int rq_servact = cdb[1];
 379     struct prin_resp resp;
 380     size_t written;
 381     int r;
 382
 383     switch (rq_servact) {
 384     case MPATH_PRIN_RKEY_SA:
 385     case MPATH_PRIN_RRES_SA:
 386     case MPATH_PRIN_RCAP_SA:
 387         break;
 388     case MPATH_PRIN_RFSTAT_SA:
 389         /* Nobody implements it anyway, so bail out. */
 390     default:
 391         /* Cannot parse any other output.  */
 392         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 393         return CHECK_CONDITION;
 394     }
 395
 396     r = mpath_persistent_reserve_in(fd, rq_servact, &resp, noisy, verbose);
 397     if (r == MPATH_PR_SUCCESS) {
 398         switch (rq_servact) {
 399         case MPATH_PRIN_RKEY_SA:
 400         case MPATH_PRIN_RRES_SA: {
 401             struct prin_readdescr *out = &resp.prin_descriptor.prin_readkeys;
 402             assert(sz >= 8);
 403             written = MIN(out->additional_length + 8, sz);
 404             stl_be_p(&data[0], out->prgeneration);
 405             stl_be_p(&data[4], out->additional_length);
 406             memcpy(&data[8], out->key_list, written - 8);
 407             break;
 408         }
 409         case MPATH_PRIN_RCAP_SA: {
 410             struct prin_capdescr *out = &resp.prin_descriptor.prin_readcap;
 411             assert(sz >= 6);
 412             written = 6;
 413             stw_be_p(&data[0], out->length);
 414             data[2] = out->flags[0];
 415             data[3] = out->flags[1];
 416             stw_be_p(&data[4], out->pr_type_mask);
 417             break;
 418         }
 419         default:
 420             scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 421             return CHECK_CONDITION;
 422         }
 423         assert(written <= sz);
 424         memset(data + written, 0, sz - written);
 425     }
 426
 427     return mpath_reconstruct_sense(fd, r, sense);
 428 }
 429
 430 static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 431                             const uint8_t *param, int sz)
 432 {
 433     int rq_servact = cdb[1];
 434     int rq_scope = cdb[2] >> 4;
 435     int rq_type = cdb[2] & 0xf;
 436     g_autofree struct prout_param_descriptor *paramp = NULL;
 437     char transportids[PR_HELPER_DATA_SIZE];
 438     int r;
 439
 440     paramp = g_malloc0(sizeof(struct prout_param_descriptor)
 441                        + sizeof(struct transportid *) * MPATH_MX_TIDS);
 442
 443     if (sz < PR_OUT_FIXED_PARAM_SIZE) {
 444         /* Illegal request, Parameter list length error.  This isn't fatal;
 445          * we have read the data, send an error without closing the socket.
 446          */
 447         scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM_LEN));
 448         return CHECK_CONDITION;
 449     }
 450
 451     switch (rq_servact) {
 452     case MPATH_PROUT_REG_SA:
 453     case MPATH_PROUT_RES_SA:
 454     case MPATH_PROUT_REL_SA:
 455     case MPATH_PROUT_CLEAR_SA:
 456     case MPATH_PROUT_PREE_SA:
 457     case MPATH_PROUT_PREE_AB_SA:
 458     case MPATH_PROUT_REG_IGN_SA:
 459         break;
 460     case MPATH_PROUT_REG_MOV_SA:
 461         /* Not supported by struct prout_param_descriptor.  */
 462     default:
 463         /* Cannot parse any other input.  */
 464         scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));
 465         return CHECK_CONDITION;
 466     }
 467
 468     /* Convert input data, especially transport IDs, to the structs
 469      * used by libmpathpersist (which, of course, will immediately
 470      * do the opposite).
 471      */
 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             assert(paramp->num_transportid < MPATH_MX_TIDS);
 538             paramp->trnptid_list[paramp->num_transportid++] = id;
 539         }
 540     }
 541
 542     r = mpath_persistent_reserve_out(fd, rq_servact, rq_scope, rq_type,
 543                                      paramp, noisy, verbose);
 544     return mpath_reconstruct_sense(fd, r, sense);
 545 }
 546 #endif
 547
 548 static int do_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,
 549                     uint8_t *data, int *resp_sz)
 550 {
 551 #ifdef CONFIG_MPATH
 552     if (is_mpath(fd)) {
 553         /* multipath_pr_in fills the whole input buffer.  */
 554         int r = multipath_pr_in(fd, cdb, sense, data, *resp_sz);
 555         if (r != GOOD) {
 556             *resp_sz = 0;
 557         }
 558         return r;
 559     }
 560 #endif
 561
 562     return do_sgio(fd, cdb, sense, data, resp_sz,
 563                    SG_DXFER_FROM_DEV);
 564 }
 565
 566 static int do_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,
 567                      const uint8_t *param, int sz)
 568 {
 569     int resp_sz;
 570
 571     if ((fcntl(fd, F_GETFL) & O_ACCMODE) == O_RDONLY) {
 572         scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));
 573         return CHECK_CONDITION;
 574     }
 575
 576 #ifdef CONFIG_MPATH
 577     if (is_mpath(fd)) {
 578         return multipath_pr_out(fd, cdb, sense, param, sz);
 579     }
 580 #endif
 581
 582     resp_sz = sz;
 583     return do_sgio(fd, cdb, sense, (uint8_t *)param, &resp_sz,
 584                    SG_DXFER_TO_DEV);
 585 }
 586
 587 /* Client */
 588
 589 typedef struct PRHelperClient {
 590     QIOChannelSocket *ioc;
 591     Coroutine *co;
 592     int fd;
 593     uint8_t data[PR_HELPER_DATA_SIZE];
 594 } PRHelperClient;
 595
 596 typedef struct PRHelperRequest {
 597     int fd;
 598     size_t sz;
 599     uint8_t cdb[PR_HELPER_CDB_SIZE];
 600 } PRHelperRequest;
 601
 602 static int coroutine_fn prh_read(PRHelperClient *client, void *buf, int sz,
 603                                  Error **errp)
 604 {
 605     int ret = 0;
 606
 607     while (sz > 0) {
 608         int *fds = NULL;
 609         size_t nfds = 0;
 610         int i;
 611         struct iovec iov;
 612         ssize_t n_read;
 613
 614         iov.iov_base = buf;
 615         iov.iov_len = sz;
 616         n_read = qio_channel_readv_full(QIO_CHANNEL(client->ioc), &iov, 1,
 617                                         &fds, &nfds, 0, errp);
 618
 619         if (n_read == QIO_CHANNEL_ERR_BLOCK) {
 620             qio_channel_yield(QIO_CHANNEL(client->ioc), G_IO_IN);
 621             continue;
 622         }
 623         if (n_read <= 0) {
 624             ret = n_read ? n_read : -1;
 625             goto err;
 626         }
 627
 628         /* Stash one file descriptor per request.  */
 629         if (nfds) {
 630             bool too_many = false;
 631             for (i = 0; i < nfds; i++) {
 632                 if (client->fd == -1) {
 633                     client->fd = fds[i];
 634                 } else {
 635                     close(fds[i]);
 636                     too_many = true;
 637                 }
 638             }
 639             g_free(fds);
 640             if (too_many) {
 641                 ret = -1;
 642                 goto err;
 643             }
 644         }
 645
 646         buf += n_read;
 647         sz -= n_read;
 648     }
 649
 650     return 0;
 651
 652 err:
 653     if (client->fd != -1) {
 654         close(client->fd);
 655         client->fd = -1;
 656     }
 657     return ret;
 658 }
 659
 660 static int coroutine_fn prh_read_request(PRHelperClient *client,
 661                                          PRHelperRequest *req,
 662                                          PRHelperResponse *resp, Error **errp)
 663 {
 664     uint32_t sz;
 665
 666     if (prh_read(client, req->cdb, sizeof(req->cdb), NULL) < 0) {
 667         return -1;
 668     }
 669
 670     if (client->fd == -1) {
 671         error_setg(errp, "No file descriptor in request.");
 672         return -1;
 673     }
 674
 675     if (req->cdb[0] != PERSISTENT_RESERVE_OUT &&
 676         req->cdb[0] != PERSISTENT_RESERVE_IN) {
 677         error_setg(errp, "Invalid CDB, closing socket.");
 678         goto out_close;
 679     }
 680
 681     sz = scsi_cdb_xfer(req->cdb);
 682     if (sz > sizeof(client->data)) {
 683         goto out_close;
 684     }
 685
 686     if (req->cdb[0] == PERSISTENT_RESERVE_OUT) {
 687         if (qio_channel_read_all(QIO_CHANNEL(client->ioc),
 688                                  (char *)client->data, sz,
 689                                  errp) < 0) {
 690             goto out_close;
 691         }
 692     }
 693
 694     req->fd = client->fd;
 695     req->sz = sz;
 696     client->fd = -1;
 697     return sz;
 698
 699 out_close:
 700     close(client->fd);
 701     client->fd = -1;
 702     return -1;
 703 }
 704
 705 static int coroutine_fn prh_write_response(PRHelperClient *client,
 706                                            PRHelperRequest *req,
 707                                            PRHelperResponse *resp, Error **errp)
 708 {
 709     ssize_t r;
 710     size_t sz;
 711
 712     if (req->cdb[0] == PERSISTENT_RESERVE_IN && resp->result == GOOD) {
 713         assert(resp->sz <= req->sz && resp->sz <= sizeof(client->data));
 714     } else {
 715         assert(resp->sz == 0);
 716     }
 717
 718     sz = resp->sz;
 719
 720     resp->result = cpu_to_be32(resp->result);
 721     resp->sz = cpu_to_be32(resp->sz);
 722     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 723                               (char *) resp, sizeof(*resp), errp);
 724     if (r < 0) {
 725         return r;
 726     }
 727
 728     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 729                               (char *) client->data,
 730                               sz, errp);
 731     return r < 0 ? r : 0;
 732 }
 733
 734 static void coroutine_fn prh_co_entry(void *opaque)
 735 {
 736     PRHelperClient *client = opaque;
 737     Error *local_err = NULL;
 738     uint32_t flags;
 739     int r;
 740
 741     qio_channel_set_blocking(QIO_CHANNEL(client->ioc),
 742                              false, NULL);
 743     qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc),
 744                                    qemu_get_aio_context());
 745
 746     /* A very simple negotiation for future extensibility.  No features
 747      * are defined so write 0.
 748      */
 749     flags = cpu_to_be32(0);
 750     r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
 751                              (char *) &flags, sizeof(flags), NULL);
 752     if (r < 0) {
 753         goto out;
 754     }
 755
 756     r = qio_channel_read_all(QIO_CHANNEL(client->ioc),
 757                              (char *) &flags, sizeof(flags), NULL);
 758     if (be32_to_cpu(flags) != 0 || r < 0) {
 759         goto out;
 760     }
 761
 762     while (qatomic_read(&state) == RUNNING) {
 763         PRHelperRequest req;
 764         PRHelperResponse resp;
 765         int sz;
 766
 767         sz = prh_read_request(client, &req, &resp, &local_err);
 768         if (sz < 0) {
 769             break;
 770         }
 771
 772         num_active_sockets++;
 773         if (req.cdb[0] == PERSISTENT_RESERVE_OUT) {
 774             r = do_pr_out(req.fd, req.cdb, resp.sense,
 775                           client->data, sz);
 776             resp.sz = 0;
 777         } else {
 778             resp.sz = sizeof(client->data);
 779             r = do_pr_in(req.fd, req.cdb, resp.sense,
 780                          client->data, &resp.sz);
 781             resp.sz = MIN(resp.sz, sz);
 782         }
 783         num_active_sockets--;
 784         close(req.fd);
 785         if (r == -1) {
 786             break;
 787         }
 788         resp.result = r;
 789
 790         if (prh_write_response(client, &req, &resp, &local_err) < 0) {
 791             break;
 792         }
 793     }
 794
 795     if (local_err) {
 796         if (verbose == 0) {
 797             error_free(local_err);
 798         } else {
 799             error_report_err(local_err);
 800         }
 801     }
 802
 803 out:
 804     qio_channel_detach_aio_context(QIO_CHANNEL(client->ioc));
 805     object_unref(OBJECT(client->ioc));
 806     g_free(client);
 807 }
 808
 809 static gboolean accept_client(QIOChannel *ioc, GIOCondition cond, gpointer opaque)
 810 {
 811     QIOChannelSocket *cioc;
 812     PRHelperClient *prh;
 813
 814     cioc = qio_channel_socket_accept(QIO_CHANNEL_SOCKET(ioc),
 815                                      NULL);
 816     if (!cioc) {
 817         return TRUE;
 818     }
 819
 820     prh = g_new(PRHelperClient, 1);
 821     prh->ioc = cioc;
 822     prh->fd = -1;
 823     prh->co = qemu_coroutine_create(prh_co_entry, prh);
 824     qemu_coroutine_enter(prh->co);
 825
 826     return TRUE;
 827 }
 828
 829 static void termsig_handler(int signum)
 830 {
 831     qatomic_cmpxchg(&state, RUNNING, TERMINATE);
 832     qemu_notify_event();
 833 }
 834
 835 static void close_server_socket(void)
 836 {
 837     assert(server_ioc);
 838
 839     g_source_remove(server_watch);
 840     server_watch = -1;
 841     object_unref(OBJECT(server_ioc));
 842     num_active_sockets--;
 843 }
 844
 845 #ifdef CONFIG_LIBCAP_NG
 846 static int drop_privileges(void)
 847 {
 848     /* clear all capabilities */
 849     capng_clear(CAPNG_SELECT_BOTH);
 850
 851     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 852                      CAP_SYS_RAWIO) < 0) {
 853         return -1;
 854     }
 855
 856 #ifdef CONFIG_MPATH
 857     /* For /dev/mapper/control ioctls */
 858     if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
 859                      CAP_SYS_ADMIN) < 0) {
 860         return -1;
 861     }
 862 #endif
 863
 864     /* Change user/group id, retaining the capabilities.  Because file descriptors
 865      * are passed via SCM_RIGHTS, we don't need supplementary groups (and in
 866      * fact the helper can run as "nobody").
 867      */
 868     if (capng_change_id(uid != -1 ? uid : getuid(),
 869                         gid != -1 ? gid : getgid(),
 870                         CAPNG_DROP_SUPP_GRP | CAPNG_CLEAR_BOUNDING)) {
 871         return -1;
 872     }
 873
 874     return 0;
 875 }
 876 #endif
 877
 878 int main(int argc, char **argv)
 879 {
 880     const char *sopt = "hVk:f:dT:u:g:vq";
 881     struct option lopt[] = {
 882         { "help", no_argument, NULL, 'h' },
 883         { "version", no_argument, NULL, 'V' },
 884         { "socket", required_argument, NULL, 'k' },
 885         { "pidfile", required_argument, NULL, 'f' },
 886         { "daemon", no_argument, NULL, 'd' },
 887         { "trace", required_argument, NULL, 'T' },
 888         { "user", required_argument, NULL, 'u' },
 889         { "group", required_argument, NULL, 'g' },
 890         { "verbose", no_argument, NULL, 'v' },
 891         { "quiet", no_argument, NULL, 'q' },
 892         { NULL, 0, NULL, 0 }
 893     };
 894     int opt_ind = 0;
 895     int loglevel = 1;
 896     int quiet = 0;
 897     int ch;
 898     Error *local_err = NULL;
 899     bool daemonize = false;
 900     bool pidfile_specified = false;
 901     bool socket_path_specified = false;
 902     unsigned socket_activation;
 903
 904     struct sigaction sa_sigterm;
 905     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 906     sa_sigterm.sa_handler = termsig_handler;
 907     sigaction(SIGTERM, &sa_sigterm, NULL);
 908     sigaction(SIGINT, &sa_sigterm, NULL);
 909     sigaction(SIGHUP, &sa_sigterm, NULL);
 910
 911     signal(SIGPIPE, SIG_IGN);
 912
 913     error_init(argv[0]);
 914     module_call_init(MODULE_INIT_TRACE);
 915     module_call_init(MODULE_INIT_QOM);
 916     qemu_add_opts(&qemu_trace_opts);
 917     qemu_init_exec_dir(argv[0]);
 918
 919     compute_default_paths();
 920
 921     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 922         switch (ch) {
 923         case 'k':
 924             g_free(socket_path);
 925             socket_path = g_strdup(optarg);
 926             socket_path_specified = true;
 927             if (socket_path[0] != '/') {
 928                 error_report("socket path must be absolute");
 929                 exit(EXIT_FAILURE);
 930             }
 931             break;
 932         case 'f':
 933             g_free(pidfile);
 934             pidfile = g_strdup(optarg);
 935             pidfile_specified = true;
 936             break;
 937 #ifdef CONFIG_LIBCAP_NG
 938         case 'u': {
 939             unsigned long res;
 940             struct passwd *userinfo = getpwnam(optarg);
 941             if (userinfo) {
 942                 uid = userinfo->pw_uid;
 943             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 944                        (uid_t)res == res) {
 945                 uid = res;
 946             } else {
 947                 error_report("invalid user '%s'", optarg);
 948                 exit(EXIT_FAILURE);
 949             }
 950             break;
 951         }
 952         case 'g': {
 953             unsigned long res;
 954             struct group *groupinfo = getgrnam(optarg);
 955             if (groupinfo) {
 956                 gid = groupinfo->gr_gid;
 957             } else if (qemu_strtoul(optarg, NULL, 10, &res) == 0 &&
 958                        (gid_t)res == res) {
 959                 gid = res;
 960             } else {
 961                 error_report("invalid group '%s'", optarg);
 962                 exit(EXIT_FAILURE);
 963             }
 964             break;
 965         }
 966 #else
 967         case 'u':
 968         case 'g':
 969             error_report("-%c not supported by this %s", ch, argv[0]);
 970             exit(1);
 971 #endif
 972         case 'd':
 973             daemonize = true;
 974             break;
 975         case 'q':
 976             quiet = 1;
 977             break;
 978         case 'v':
 979             ++loglevel;
 980             break;
 981         case 'T':
 982             trace_opt_parse(optarg);
 983             break;
 984         case 'V':
 985             version(argv[0]);
 986             exit(EXIT_SUCCESS);
 987             break;
 988         case 'h':
 989             usage(argv[0]);
 990             exit(EXIT_SUCCESS);
 991             break;
 992         case '?':
 993             error_report("Try `%s --help' for more information.", argv[0]);
 994             exit(EXIT_FAILURE);
 995         }
 996     }
 997
 998     /* set verbosity */
 999     noisy = !quiet && (loglevel >= 3);
1000     verbose = quiet ? 0 : MIN(loglevel, 3);
1001
1002     if (!trace_init_backends()) {
1003         exit(EXIT_FAILURE);
1004     }
1005     trace_init_file();
1006     qemu_set_log(LOG_TRACE, &error_fatal);
1007
1008 #ifdef CONFIG_MPATH
1009     dm_init();
1010     multipath_pr_init();
1011 #endif
1012
1013     socket_activation = check_socket_activation();
1014     if (socket_activation == 0) {
1015         SocketAddress saddr;
1016         saddr = (SocketAddress){
1017             .type = SOCKET_ADDRESS_TYPE_UNIX,
1018             .u.q_unix.path = socket_path,
1019         };
1020         server_ioc = qio_channel_socket_new();
1021         if (qio_channel_socket_listen_sync(server_ioc, &saddr,
1022                                            1, &local_err) < 0) {
1023             object_unref(OBJECT(server_ioc));
1024             error_report_err(local_err);
1025             return 1;
1026         }
1027     } else {
1028         /* Using socket activation - check user didn't use -p etc. */
1029         if (socket_path_specified) {
1030             error_report("Unix socket can't be set when using socket activation");
1031             exit(EXIT_FAILURE);
1032         }
1033
1034         /* Can only listen on a single socket.  */
1035         if (socket_activation > 1) {
1036             error_report("%s does not support socket activation with LISTEN_FDS > 1",
1037                          argv[0]);
1038             exit(EXIT_FAILURE);
1039         }
1040         server_ioc = qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_FD,
1041                                                &local_err);
1042         if (server_ioc == NULL) {
1043             error_reportf_err(local_err,
1044                               "Failed to use socket activation: ");
1045             exit(EXIT_FAILURE);
1046         }
1047     }
1048
1049     qemu_init_main_loop(&error_fatal);
1050
1051     server_watch = qio_channel_add_watch(QIO_CHANNEL(server_ioc),
1052                                          G_IO_IN,
1053                                          accept_client,
1054                                          NULL, NULL);
1055
1056     if (daemonize) {
1057         if (daemon(0, 0) < 0) {
1058             error_report("Failed to daemonize: %s", strerror(errno));
1059             exit(EXIT_FAILURE);
1060         }
1061     }
1062
1063     if (daemonize || pidfile_specified) {
1064         qemu_write_pidfile(pidfile, &error_fatal);
1065     }
1066
1067 #ifdef CONFIG_LIBCAP_NG
1068     if (drop_privileges() < 0) {
1069         error_report("Failed to drop privileges: %s", strerror(errno));
1070         exit(EXIT_FAILURE);
1071     }
1072 #endif
1073
1074     state = RUNNING;
1075     do {
1076         main_loop_wait(false);
1077         if (state == TERMINATE) {
1078             state = TERMINATING;
1079             close_server_socket();
1080         }
1081     } while (num_active_sockets > 0);
1082
1083     exit(EXIT_SUCCESS);
1084 }