src/logind-seat.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/ioctl.h>
  27 #include <linux/vt.h>
  28 #include <string.h>
  29
  30 #include "logind-seat.h"
  31 #include "logind-acl.h"
  32 #include "util.h"
  33
  34 Seat *seat_new(Manager *m, const char *id) {
  35         Seat *s;
  36
  37         assert(m);
  38         assert(id);
  39
  40         s = new0(Seat, 1);
  41         if (!s)
  42                 return NULL;
  43
  44         s->state_file = strappend("/run/systemd/seat/", id);
  45         if (!s->state_file) {
  46                 free(s);
  47                 return NULL;
  48         }
  49
  50         s->id = file_name_from_path(s->state_file);
  51         s->manager = m;
  52
  53         if (hashmap_put(m->seats, s->id, s) < 0) {
  54                 free(s->state_file);
  55                 free(s);
  56                 return NULL;
  57         }
  58
  59         return s;
  60 }
  61
  62 void seat_free(Seat *s) {
  63         assert(s);
  64
  65         if (s->in_gc_queue)
  66                 LIST_REMOVE(Seat, gc_queue, s->manager->seat_gc_queue, s);
  67
  68         while (s->sessions)
  69                 session_free(s->sessions);
  70
  71         assert(!s->active);
  72
  73         while (s->devices)
  74                 device_free(s->devices);
  75
  76         hashmap_remove(s->manager->seats, s->id);
  77
  78         free(s->state_file);
  79         free(s);
  80 }
  81
  82 int seat_save(Seat *s) {
  83         int r;
  84         FILE *f;
  85         char *temp_path;
  86
  87         assert(s);
  88
  89         r = safe_mkdir("/run/systemd/seat", 0755, 0, 0);
  90         if (r < 0)
  91                 goto finish;
  92
  93         r = fopen_temporary(s->state_file, &f, &temp_path);
  94         if (r < 0)
  95                 goto finish;
  96
  97         fchmod(fileno(f), 0644);
  98
  99         fprintf(f,
 100                 "# This is private data. Do not parse.\n"
 101                 "IS_VTCONSOLE=%i\n",
 102                 s->manager->vtconsole == s);
 103
 104         if (s->active) {
 105                 assert(s->active->user);
 106
 107                 fprintf(f,
 108                         "ACTIVE=%s\n"
 109                         "ACTIVE_UID=%lu\n",
 110                         s->active->id,
 111                         (unsigned long) s->active->user->uid);
 112         }
 113
 114         if (s->sessions) {
 115                 Session *i;
 116
 117                 fputs("OTHER=", f);
 118                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 119                         if (i == s->active)
 120                                 continue;
 121
 122                         fprintf(f,
 123                                 "%s%c",
 124                                 i->id,
 125                                 i->sessions_by_seat_next ? ' ' : '\n');
 126                 }
 127
 128                 fputs("OTHER_UIDS=", f);
 129                 LIST_FOREACH(sessions_by_seat, i, s->sessions) {
 130                         if (i == s->active)
 131                                 continue;
 132
 133                         fprintf(f,
 134                                 "%lu%c",
 135                                 (unsigned long) i->user->uid,
 136                                 i->sessions_by_seat_next ? ' ' : '\n');
 137                 }
 138         }
 139
 140         fflush(f);
 141
 142         if (ferror(f) || rename(temp_path, s->state_file) < 0) {
 143                 r = -errno;
 144                 unlink(s->state_file);
 145                 unlink(temp_path);
 146         }
 147
 148         fclose(f);
 149         free(temp_path);
 150
 151 finish:
 152         if (r < 0)
 153                 log_error("Failed to save seat data for %s: %s", s->id, strerror(-r));
 154
 155         return r;
 156 }
 157
 158 int seat_load(Seat *s) {
 159         assert(s);
 160
 161         return 0;
 162 }
 163
 164 static int vt_allocate(int vtnr) {
 165         int fd, r;
 166         char *p;
 167
 168         assert(vtnr >= 1);
 169
 170         if (asprintf(&p, "/dev/tty%i", vtnr) < 0)
 171                 return -ENOMEM;
 172
 173         fd = open_terminal(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
 174         free(p);
 175
 176         r = fd < 0 ? -errno : 0;
 177
 178         if (fd >= 0)
 179                 close_nointr_nofail(fd);
 180
 181         return r;
 182 }
 183
 184 static int seat_preallocate_vts(Seat *s) {
 185         int r = 0;
 186         unsigned i;
 187
 188         assert(s);
 189         assert(s->manager);
 190
 191         if (s->manager->n_autovts <= 0)
 192                 return 0;
 193
 194         if (s->manager->vtconsole != s)
 195                 return 0;
 196
 197         for (i = 1; i < s->manager->n_autovts; i++) {
 198                 int q;
 199
 200                 q = vt_allocate(i);
 201                 if (q < 0) {
 202                         log_error("Failed to preallocate VT %i: %s", i, strerror(-q));
 203                         r = q;
 204                 }
 205         }
 206
 207         return r;
 208 }
 209
 210 int seat_apply_acls(Seat *s, Session *old_active) {
 211         int r;
 212
 213         assert(s);
 214
 215         r = devnode_acl_all(s->manager->udev,
 216                             s->id,
 217                             false,
 218                             !!old_active, old_active ? old_active->user->uid : 0,
 219                             !!s->active, s->active ? s->active->user->uid : 0);
 220
 221         if (r < 0)
 222                 log_error("Failed to apply ACLs: %s", strerror(-r));
 223
 224         return r;
 225 }
 226
 227 int seat_active_vt_changed(Seat *s, int vtnr) {
 228         Session *i, *new_active = NULL, *old_active;
 229
 230         assert(s);
 231         assert(vtnr >= 1);
 232
 233         if (s->manager->vtconsole != s)
 234                 return -EINVAL;
 235
 236         log_debug("VT changed to %i", vtnr);
 237
 238         LIST_FOREACH(sessions_by_seat, i, s->sessions)
 239                 if (i->vtnr == vtnr) {
 240                         new_active = i;
 241                         break;
 242                 }
 243
 244         if (new_active == s->active)
 245                 return 0;
 246
 247         old_active = s->active;
 248         s->active = new_active;
 249
 250         seat_apply_acls(s, old_active);
 251         manager_spawn_autovt(s->manager, vtnr);
 252
 253         return 0;
 254 }
 255
 256 int seat_read_active_vt(Seat *s) {
 257         char t[64];
 258         ssize_t k;
 259         int r, vtnr;
 260
 261         assert(s);
 262
 263         if (s->manager->vtconsole != s)
 264                 return 0;
 265
 266         lseek(s->manager->console_active_fd, SEEK_SET, 0);
 267
 268         k = read(s->manager->console_active_fd, t, sizeof(t)-1);
 269         if (k <= 0) {
 270                 log_error("Failed to read current console: %s", k < 0 ? strerror(-errno) : "EOF");
 271                 return k < 0 ? -errno : -EIO;
 272         }
 273
 274         t[k] = 0;
 275         truncate_nl(t);
 276
 277         if (!startswith(t, "tty")) {
 278                 log_error("Hm, /sys/class/tty/tty0/active is badly formatted.");
 279                 return -EIO;
 280         }
 281
 282         r = safe_atoi(t+3, &vtnr);
 283         if (r < 0) {
 284                 log_error("Failed to parse VT number %s", t+3);
 285                 return r;
 286         }
 287
 288         if (vtnr <= 0) {
 289                 log_error("VT number invalid: %s", t+3);
 290                 return -EIO;
 291         }
 292
 293         return seat_active_vt_changed(s, vtnr);
 294 }
 295
 296 int seat_start(Seat *s) {
 297         assert(s);
 298
 299         if (s->started)
 300                 return 0;
 301
 302         log_info("New seat %s.", s->id);
 303
 304         /* Initialize VT magic stuff */
 305         seat_preallocate_vts(s);
 306
 307         /* Read current VT */
 308         seat_read_active_vt(s);
 309
 310         /* Save seat data */
 311         seat_save(s);
 312
 313         s->started = true;
 314
 315         return 0;
 316 }
 317
 318 int seat_stop(Seat *s) {
 319         Session *session;
 320         int r = 0, k;
 321
 322         assert(s);
 323
 324         if (!s->started)
 325                 return 0;
 326
 327         log_info("Removed seat %s.", s->id);
 328
 329         LIST_FOREACH(sessions_by_seat, session, s->sessions) {
 330                 k = session_stop(session);
 331                 if (k < 0)
 332                         r = k;
 333         }
 334
 335         unlink(s->state_file);
 336         seat_add_to_gc_queue(s);
 337
 338         s->started = false;
 339
 340         return r;
 341 }
 342
 343 int seat_check_gc(Seat *s) {
 344         assert(s);
 345
 346         if (s->manager->vtconsole == s)
 347                 return 1;
 348
 349         return !!s->devices;
 350 }
 351
 352 void seat_add_to_gc_queue(Seat *s) {
 353         assert(s);
 354
 355         if (s->in_gc_queue)
 356                 return;
 357
 358         LIST_PREPEND(Seat, gc_queue, s->manager->seat_gc_queue, s);
 359         s->in_gc_queue = true;
 360 }
 361
 362 static bool seat_name_valid_char(char c) {
 363         return
 364                 (c >= 'a' && c <= 'z') ||
 365                 (c >= 'A' && c <= 'Z') ||
 366                 (c >= '0' && c <= '9') ||
 367                 c == '-' ||
 368                 c == '_';
 369 }
 370
 371 bool seat_name_is_valid(const char *name) {
 372         const char *p;
 373
 374         assert(name);
 375
 376         if (!startswith(name, "seat"))
 377                 return false;
 378
 379         if (!name[4])
 380                 return false;
 381
 382         for (p = name; *p; p++)
 383                 if (!seat_name_valid_char(*p))
 384                         return false;
 385
 386         return true;
 387 }