fs/quota/quota.c

   1 /*
   2  * Quota code necessary even when VFS quota support is not compiled
   3  * into the kernel.  The interesting stuff is over in dquot.c, here
   4  * we have symbols for initial quotactl(2) handling, the sysctl(2)
   5  * variables, etc - things needed even when quota support disabled.
   6  */
   7
   8 #include <linux/fs.h>
   9 #include <linux/namei.h>
  10 #include <linux/slab.h>
  11 #include <asm/current.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/kernel.h>
  14 #include <linux/security.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/capability.h>
  17 #include <linux/quotaops.h>
  18 #include <linux/types.h>
  19 #include <linux/writeback.h>
  20
  21 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  22                                      qid_t id)
  23 {
  24         switch (cmd) {
  25         /* these commands do not require any special privilegues */
  26         case Q_GETFMT:
  27         case Q_SYNC:
  28         case Q_GETINFO:
  29         case Q_XGETQSTAT:
  30         case Q_XGETQSTATV:
  31         case Q_XQUOTASYNC:
  32                 break;
  33         /* allow to query information for dquots we "own" */
  34         case Q_GETQUOTA:
  35         case Q_XGETQUOTA:
  36                 if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
  37                     (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
  38                         break;
  39                 /*FALLTHROUGH*/
  40         default:
  41                 if (!capable(CAP_SYS_ADMIN))
  42                         return -EPERM;
  43         }
  44
  45         return security_quotactl(cmd, type, id, sb);
  46 }
  47
  48 static void quota_sync_one(struct super_block *sb, void *arg)
  49 {
  50         if (sb->s_qcop && sb->s_qcop->quota_sync)
  51                 sb->s_qcop->quota_sync(sb, *(int *)arg);
  52 }
  53
  54 static int quota_sync_all(int type)
  55 {
  56         int ret;
  57
  58         if (type >= MAXQUOTAS)
  59                 return -EINVAL;
  60         ret = security_quotactl(Q_SYNC, type, 0, NULL);
  61         if (!ret)
  62                 iterate_supers(quota_sync_one, &type);
  63         return ret;
  64 }
  65
  66 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
  67                          struct path *path)
  68 {
  69         if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
  70                 return -ENOSYS;
  71         if (sb->s_qcop->quota_on_meta)
  72                 return sb->s_qcop->quota_on_meta(sb, type, id);
  73         if (IS_ERR(path))
  74                 return PTR_ERR(path);
  75         return sb->s_qcop->quota_on(sb, type, id, path);
  76 }
  77
  78 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
  79 {
  80         __u32 fmt;
  81
  82         down_read(&sb_dqopt(sb)->dqptr_sem);
  83         if (!sb_has_quota_active(sb, type)) {
  84                 up_read(&sb_dqopt(sb)->dqptr_sem);
  85                 return -ESRCH;
  86         }
  87         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
  88         up_read(&sb_dqopt(sb)->dqptr_sem);
  89         if (copy_to_user(addr, &fmt, sizeof(fmt)))
  90                 return -EFAULT;
  91         return 0;
  92 }
  93
  94 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
  95 {
  96         struct if_dqinfo info;
  97         int ret;
  98
  99         if (!sb->s_qcop->get_info)
 100                 return -ENOSYS;
 101         ret = sb->s_qcop->get_info(sb, type, &info);
 102         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 103                 return -EFAULT;
 104         return ret;
 105 }
 106
 107 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 108 {
 109         struct if_dqinfo info;
 110
 111         if (copy_from_user(&info, addr, sizeof(info)))
 112                 return -EFAULT;
 113         if (!sb->s_qcop->set_info)
 114                 return -ENOSYS;
 115         return sb->s_qcop->set_info(sb, type, &info);
 116 }
 117
 118 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 119 {
 120         memset(dst, 0, sizeof(*dst));
 121         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 122         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 123         dst->dqb_curspace = src->d_bcount;
 124         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 125         dst->dqb_isoftlimit = src->d_ino_softlimit;
 126         dst->dqb_curinodes = src->d_icount;
 127         dst->dqb_btime = src->d_btimer;
 128         dst->dqb_itime = src->d_itimer;
 129         dst->dqb_valid = QIF_ALL;
 130 }
 131
 132 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 133                           void __user *addr)
 134 {
 135         struct kqid qid;
 136         struct fs_disk_quota fdq;
 137         struct if_dqblk idq;
 138         int ret;
 139
 140         if (!sb->s_qcop->get_dqblk)
 141                 return -ENOSYS;
 142         qid = make_kqid(current_user_ns(), type, id);
 143         if (!qid_valid(qid))
 144                 return -EINVAL;
 145         ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
 146         if (ret)
 147                 return ret;
 148         copy_to_if_dqblk(&idq, &fdq);
 149         if (copy_to_user(addr, &idq, sizeof(idq)))
 150                 return -EFAULT;
 151         return 0;
 152 }
 153
 154 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
 155 {
 156         dst->d_blk_hardlimit = src->dqb_bhardlimit;
 157         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
 158         dst->d_bcount = src->dqb_curspace;
 159         dst->d_ino_hardlimit = src->dqb_ihardlimit;
 160         dst->d_ino_softlimit = src->dqb_isoftlimit;
 161         dst->d_icount = src->dqb_curinodes;
 162         dst->d_btimer = src->dqb_btime;
 163         dst->d_itimer = src->dqb_itime;
 164
 165         dst->d_fieldmask = 0;
 166         if (src->dqb_valid & QIF_BLIMITS)
 167                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
 168         if (src->dqb_valid & QIF_SPACE)
 169                 dst->d_fieldmask |= FS_DQ_BCOUNT;
 170         if (src->dqb_valid & QIF_ILIMITS)
 171                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
 172         if (src->dqb_valid & QIF_INODES)
 173                 dst->d_fieldmask |= FS_DQ_ICOUNT;
 174         if (src->dqb_valid & QIF_BTIME)
 175                 dst->d_fieldmask |= FS_DQ_BTIMER;
 176         if (src->dqb_valid & QIF_ITIME)
 177                 dst->d_fieldmask |= FS_DQ_ITIMER;
 178 }
 179
 180 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 181                           void __user *addr)
 182 {
 183         struct fs_disk_quota fdq;
 184         struct if_dqblk idq;
 185         struct kqid qid;
 186
 187         if (copy_from_user(&idq, addr, sizeof(idq)))
 188                 return -EFAULT;
 189         if (!sb->s_qcop->set_dqblk)
 190                 return -ENOSYS;
 191         qid = make_kqid(current_user_ns(), type, id);
 192         if (!qid_valid(qid))
 193                 return -EINVAL;
 194         copy_from_if_dqblk(&fdq, &idq);
 195         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 196 }
 197
 198 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 199 {
 200         __u32 flags;
 201
 202         if (copy_from_user(&flags, addr, sizeof(flags)))
 203                 return -EFAULT;
 204         if (!sb->s_qcop->set_xstate)
 205                 return -ENOSYS;
 206         return sb->s_qcop->set_xstate(sb, flags, cmd);
 207 }
 208
 209 static int quota_getxstate(struct super_block *sb, void __user *addr)
 210 {
 211         struct fs_quota_stat fqs;
 212         int ret;
 213
 214         if (!sb->s_qcop->get_xstate)
 215                 return -ENOSYS;
 216         ret = sb->s_qcop->get_xstate(sb, &fqs);
 217         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 218                 return -EFAULT;
 219         return ret;
 220 }
 221
 222 static int quota_getxstatev(struct super_block *sb, void __user *addr)
 223 {
 224         struct fs_quota_statv fqs;
 225         int ret;
 226
 227         if (!sb->s_qcop->get_xstatev)
 228                 return -ENOSYS;
 229
 230         memset(&fqs, 0, sizeof(fqs));
 231         if (copy_from_user(&fqs, addr, 1)) /* Just read qs_version */
 232                 return -EFAULT;
 233
 234         /* If this kernel doesn't support user specified version, fail */
 235         switch (fqs.qs_version) {
 236         case FS_QSTATV_VERSION1:
 237                 break;
 238         default:
 239                 return -EINVAL;
 240         }
 241         ret = sb->s_qcop->get_xstatev(sb, &fqs);
 242         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 243                 return -EFAULT;
 244         return ret;
 245 }
 246
 247 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 248                            void __user *addr)
 249 {
 250         struct fs_disk_quota fdq;
 251         struct kqid qid;
 252
 253         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 254                 return -EFAULT;
 255         if (!sb->s_qcop->set_dqblk)
 256                 return -ENOSYS;
 257         qid = make_kqid(current_user_ns(), type, id);
 258         if (!qid_valid(qid))
 259                 return -EINVAL;
 260         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 261 }
 262
 263 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 264                            void __user *addr)
 265 {
 266         struct fs_disk_quota fdq;
 267         struct kqid qid;
 268         int ret;
 269
 270         if (!sb->s_qcop->get_dqblk)
 271                 return -ENOSYS;
 272         qid = make_kqid(current_user_ns(), type, id);
 273         if (!qid_valid(qid))
 274                 return -EINVAL;
 275         ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
 276         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 277                 return -EFAULT;
 278         return ret;
 279 }
 280
 281 static int quota_rmxquota(struct super_block *sb, void __user *addr)
 282 {
 283         __u32 flags;
 284
 285         if (copy_from_user(&flags, addr, sizeof(flags)))
 286                 return -EFAULT;
 287         if (!sb->s_qcop->rm_xquota)
 288                 return -ENOSYS;
 289         return sb->s_qcop->rm_xquota(sb, flags);
 290 }
 291
 292 /* Copy parameters and call proper function */
 293 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 294                        void __user *addr, struct path *path)
 295 {
 296         int ret;
 297
 298         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 299                 return -EINVAL;
 300         if (!sb->s_qcop)
 301                 return -ENOSYS;
 302
 303         ret = check_quotactl_permission(sb, type, cmd, id);
 304         if (ret < 0)
 305                 return ret;
 306
 307         switch (cmd) {
 308         case Q_QUOTAON:
 309                 return quota_quotaon(sb, type, cmd, id, path);
 310         case Q_QUOTAOFF:
 311                 if (!sb->s_qcop->quota_off)
 312                         return -ENOSYS;
 313                 return sb->s_qcop->quota_off(sb, type);
 314         case Q_GETFMT:
 315                 return quota_getfmt(sb, type, addr);
 316         case Q_GETINFO:
 317                 return quota_getinfo(sb, type, addr);
 318         case Q_SETINFO:
 319                 return quota_setinfo(sb, type, addr);
 320         case Q_GETQUOTA:
 321                 return quota_getquota(sb, type, id, addr);
 322         case Q_SETQUOTA:
 323                 return quota_setquota(sb, type, id, addr);
 324         case Q_SYNC:
 325                 if (!sb->s_qcop->quota_sync)
 326                         return -ENOSYS;
 327                 return sb->s_qcop->quota_sync(sb, type);
 328         case Q_XQUOTAON:
 329         case Q_XQUOTAOFF:
 330                 return quota_setxstate(sb, cmd, addr);
 331         case Q_XQUOTARM:
 332                 return quota_rmxquota(sb, addr);
 333         case Q_XGETQSTAT:
 334                 return quota_getxstate(sb, addr);
 335         case Q_XGETQSTATV:
 336                 return quota_getxstatev(sb, addr);
 337         case Q_XSETQLIM:
 338                 return quota_setxquota(sb, type, id, addr);
 339         case Q_XGETQUOTA:
 340                 return quota_getxquota(sb, type, id, addr);
 341         case Q_XQUOTASYNC:
 342                 if (sb->s_flags & MS_RDONLY)
 343                         return -EROFS;
 344                 /* XFS quotas are fully coherent now, making this call a noop */
 345                 return 0;
 346         default:
 347                 return -EINVAL;
 348         }
 349 }
 350
 351 #ifdef CONFIG_BLOCK
 352
 353 /* Return 1 if 'cmd' will block on frozen filesystem */
 354 static int quotactl_cmd_write(int cmd)
 355 {
 356         switch (cmd) {
 357         case Q_GETFMT:
 358         case Q_GETINFO:
 359         case Q_SYNC:
 360         case Q_XGETQSTAT:
 361         case Q_XGETQSTATV:
 362         case Q_XGETQUOTA:
 363         case Q_XQUOTASYNC:
 364                 return 0;
 365         }
 366         return 1;
 367 }
 368
 369 #endif /* CONFIG_BLOCK */
 370
 371 /*
 372  * look up a superblock on which quota ops will be performed
 373  * - use the name of a block device to find the superblock thereon
 374  */
 375 static struct super_block *quotactl_block(const char __user *special, int cmd)
 376 {
 377 #ifdef CONFIG_BLOCK
 378         struct block_device *bdev;
 379         struct super_block *sb;
 380         struct filename *tmp = getname(special);
 381
 382         if (IS_ERR(tmp))
 383                 return ERR_CAST(tmp);
 384         bdev = lookup_bdev(tmp->name);
 385         putname(tmp);
 386         if (IS_ERR(bdev))
 387                 return ERR_CAST(bdev);
 388         if (quotactl_cmd_write(cmd))
 389                 sb = get_super_thawed(bdev);
 390         else
 391                 sb = get_super(bdev);
 392         bdput(bdev);
 393         if (!sb)
 394                 return ERR_PTR(-ENODEV);
 395
 396         return sb;
 397 #else
 398         return ERR_PTR(-ENODEV);
 399 #endif
 400 }
 401
 402 /*
 403  * This is the system call interface. This communicates with
 404  * the user-level programs. Currently this only supports diskquota
 405  * calls. Maybe we need to add the process quotas etc. in the future,
 406  * but we probably should use rlimits for that.
 407  */
 408 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 409                 qid_t, id, void __user *, addr)
 410 {
 411         uint cmds, type;
 412         struct super_block *sb = NULL;
 413         struct path path, *pathp = NULL;
 414         int ret;
 415
 416         cmds = cmd >> SUBCMDSHIFT;
 417         type = cmd & SUBCMDMASK;
 418
 419         /*
 420          * As a special case Q_SYNC can be called without a specific device.
 421          * It will iterate all superblocks that have quota enabled and call
 422          * the sync action on each of them.
 423          */
 424         if (!special) {
 425                 if (cmds == Q_SYNC)
 426                         return quota_sync_all(type);
 427                 return -ENODEV;
 428         }
 429
 430         /*
 431          * Path for quotaon has to be resolved before grabbing superblock
 432          * because that gets s_umount sem which is also possibly needed by path
 433          * resolution (think about autofs) and thus deadlocks could arise.
 434          */
 435         if (cmds == Q_QUOTAON) {
 436                 ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
 437                 if (ret)
 438                         pathp = ERR_PTR(ret);
 439                 else
 440                         pathp = &path;
 441         }
 442
 443         sb = quotactl_block(special, cmds);
 444         if (IS_ERR(sb)) {
 445                 ret = PTR_ERR(sb);
 446                 goto out;
 447         }
 448
 449         ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 450
 451         drop_super(sb);
 452 out:
 453         if (pathp && !IS_ERR(pathp))
 454                 path_put(pathp);
 455         return ret;
 456 }