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         int type = *(int *)arg;
  51
  52         if (sb->s_qcop && sb->s_qcop->quota_sync &&
  53             (sb->s_quota_types & (1 << type)))
  54                 sb->s_qcop->quota_sync(sb, type);
  55 }
  56
  57 static int quota_sync_all(int type)
  58 {
  59         int ret;
  60
  61         if (type >= MAXQUOTAS)
  62                 return -EINVAL;
  63         ret = security_quotactl(Q_SYNC, type, 0, NULL);
  64         if (!ret)
  65                 iterate_supers(quota_sync_one, &type);
  66         return ret;
  67 }
  68
  69 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
  70                          struct path *path)
  71 {
  72         if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
  73                 return -ENOSYS;
  74         if (sb->s_qcop->quota_on_meta)
  75                 return sb->s_qcop->quota_on_meta(sb, type, id);
  76         if (IS_ERR(path))
  77                 return PTR_ERR(path);
  78         return sb->s_qcop->quota_on(sb, type, id, path);
  79 }
  80
  81 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
  82 {
  83         __u32 fmt;
  84
  85         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
  86         if (!sb_has_quota_active(sb, type)) {
  87                 mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
  88                 return -ESRCH;
  89         }
  90         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
  91         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
  92         if (copy_to_user(addr, &fmt, sizeof(fmt)))
  93                 return -EFAULT;
  94         return 0;
  95 }
  96
  97 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
  98 {
  99         struct if_dqinfo info;
 100         int ret;
 101
 102         if (!sb->s_qcop->get_info)
 103                 return -ENOSYS;
 104         ret = sb->s_qcop->get_info(sb, type, &info);
 105         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 106                 return -EFAULT;
 107         return ret;
 108 }
 109
 110 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 111 {
 112         struct if_dqinfo info;
 113
 114         if (copy_from_user(&info, addr, sizeof(info)))
 115                 return -EFAULT;
 116         if (!sb->s_qcop->set_info)
 117                 return -ENOSYS;
 118         return sb->s_qcop->set_info(sb, type, &info);
 119 }
 120
 121 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 122 {
 123         memset(dst, 0, sizeof(*dst));
 124         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 125         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 126         dst->dqb_curspace = src->d_bcount;
 127         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 128         dst->dqb_isoftlimit = src->d_ino_softlimit;
 129         dst->dqb_curinodes = src->d_icount;
 130         dst->dqb_btime = src->d_btimer;
 131         dst->dqb_itime = src->d_itimer;
 132         dst->dqb_valid = QIF_ALL;
 133 }
 134
 135 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 136                           void __user *addr)
 137 {
 138         struct kqid qid;
 139         struct fs_disk_quota fdq;
 140         struct if_dqblk idq;
 141         int ret;
 142
 143         if (!sb->s_qcop->get_dqblk)
 144                 return -ENOSYS;
 145         qid = make_kqid(current_user_ns(), type, id);
 146         if (!qid_valid(qid))
 147                 return -EINVAL;
 148         ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
 149         if (ret)
 150                 return ret;
 151         copy_to_if_dqblk(&idq, &fdq);
 152         if (copy_to_user(addr, &idq, sizeof(idq)))
 153                 return -EFAULT;
 154         return 0;
 155 }
 156
 157 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
 158 {
 159         dst->d_blk_hardlimit = src->dqb_bhardlimit;
 160         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
 161         dst->d_bcount = src->dqb_curspace;
 162         dst->d_ino_hardlimit = src->dqb_ihardlimit;
 163         dst->d_ino_softlimit = src->dqb_isoftlimit;
 164         dst->d_icount = src->dqb_curinodes;
 165         dst->d_btimer = src->dqb_btime;
 166         dst->d_itimer = src->dqb_itime;
 167
 168         dst->d_fieldmask = 0;
 169         if (src->dqb_valid & QIF_BLIMITS)
 170                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
 171         if (src->dqb_valid & QIF_SPACE)
 172                 dst->d_fieldmask |= FS_DQ_BCOUNT;
 173         if (src->dqb_valid & QIF_ILIMITS)
 174                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
 175         if (src->dqb_valid & QIF_INODES)
 176                 dst->d_fieldmask |= FS_DQ_ICOUNT;
 177         if (src->dqb_valid & QIF_BTIME)
 178                 dst->d_fieldmask |= FS_DQ_BTIMER;
 179         if (src->dqb_valid & QIF_ITIME)
 180                 dst->d_fieldmask |= FS_DQ_ITIMER;
 181 }
 182
 183 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 184                           void __user *addr)
 185 {
 186         struct fs_disk_quota fdq;
 187         struct if_dqblk idq;
 188         struct kqid qid;
 189
 190         if (copy_from_user(&idq, addr, sizeof(idq)))
 191                 return -EFAULT;
 192         if (!sb->s_qcop->set_dqblk)
 193                 return -ENOSYS;
 194         qid = make_kqid(current_user_ns(), type, id);
 195         if (!qid_valid(qid))
 196                 return -EINVAL;
 197         copy_from_if_dqblk(&fdq, &idq);
 198         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 199 }
 200
 201 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 202 {
 203         __u32 flags;
 204
 205         if (copy_from_user(&flags, addr, sizeof(flags)))
 206                 return -EFAULT;
 207         if (!sb->s_qcop->set_xstate)
 208                 return -ENOSYS;
 209         return sb->s_qcop->set_xstate(sb, flags, cmd);
 210 }
 211
 212 static int quota_getxstate(struct super_block *sb, void __user *addr)
 213 {
 214         struct fs_quota_stat fqs;
 215         int ret;
 216
 217         if (!sb->s_qcop->get_xstate)
 218                 return -ENOSYS;
 219         ret = sb->s_qcop->get_xstate(sb, &fqs);
 220         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 221                 return -EFAULT;
 222         return ret;
 223 }
 224
 225 static int quota_getxstatev(struct super_block *sb, void __user *addr)
 226 {
 227         struct fs_quota_statv fqs;
 228         int ret;
 229
 230         if (!sb->s_qcop->get_xstatev)
 231                 return -ENOSYS;
 232
 233         memset(&fqs, 0, sizeof(fqs));
 234         if (copy_from_user(&fqs, addr, 1)) /* Just read qs_version */
 235                 return -EFAULT;
 236
 237         /* If this kernel doesn't support user specified version, fail */
 238         switch (fqs.qs_version) {
 239         case FS_QSTATV_VERSION1:
 240                 break;
 241         default:
 242                 return -EINVAL;
 243         }
 244         ret = sb->s_qcop->get_xstatev(sb, &fqs);
 245         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 246                 return -EFAULT;
 247         return ret;
 248 }
 249
 250 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 251                            void __user *addr)
 252 {
 253         struct fs_disk_quota fdq;
 254         struct kqid qid;
 255
 256         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 257                 return -EFAULT;
 258         if (!sb->s_qcop->set_dqblk)
 259                 return -ENOSYS;
 260         qid = make_kqid(current_user_ns(), type, id);
 261         if (!qid_valid(qid))
 262                 return -EINVAL;
 263         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 264 }
 265
 266 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 267                            void __user *addr)
 268 {
 269         struct fs_disk_quota fdq;
 270         struct kqid qid;
 271         int ret;
 272
 273         if (!sb->s_qcop->get_dqblk)
 274                 return -ENOSYS;
 275         qid = make_kqid(current_user_ns(), type, id);
 276         if (!qid_valid(qid))
 277                 return -EINVAL;
 278         ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
 279         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 280                 return -EFAULT;
 281         return ret;
 282 }
 283
 284 static int quota_rmxquota(struct super_block *sb, void __user *addr)
 285 {
 286         __u32 flags;
 287
 288         if (copy_from_user(&flags, addr, sizeof(flags)))
 289                 return -EFAULT;
 290         if (!sb->s_qcop->rm_xquota)
 291                 return -ENOSYS;
 292         return sb->s_qcop->rm_xquota(sb, flags);
 293 }
 294
 295 /* Copy parameters and call proper function */
 296 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 297                        void __user *addr, struct path *path)
 298 {
 299         int ret;
 300
 301         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 302                 return -EINVAL;
 303         /*
 304          * Quota not supported on this fs? Check this before s_quota_types
 305          * since they needn't be set if quota is not supported at all.
 306          */
 307         if (!sb->s_qcop)
 308                 return -ENOSYS;
 309         if (!(sb->s_quota_types & (1 << type)))
 310                 return -EINVAL;
 311
 312         ret = check_quotactl_permission(sb, type, cmd, id);
 313         if (ret < 0)
 314                 return ret;
 315
 316         switch (cmd) {
 317         case Q_QUOTAON:
 318                 return quota_quotaon(sb, type, cmd, id, path);
 319         case Q_QUOTAOFF:
 320                 if (!sb->s_qcop->quota_off)
 321                         return -ENOSYS;
 322                 return sb->s_qcop->quota_off(sb, type);
 323         case Q_GETFMT:
 324                 return quota_getfmt(sb, type, addr);
 325         case Q_GETINFO:
 326                 return quota_getinfo(sb, type, addr);
 327         case Q_SETINFO:
 328                 return quota_setinfo(sb, type, addr);
 329         case Q_GETQUOTA:
 330                 return quota_getquota(sb, type, id, addr);
 331         case Q_SETQUOTA:
 332                 return quota_setquota(sb, type, id, addr);
 333         case Q_SYNC:
 334                 if (!sb->s_qcop->quota_sync)
 335                         return -ENOSYS;
 336                 return sb->s_qcop->quota_sync(sb, type);
 337         case Q_XQUOTAON:
 338         case Q_XQUOTAOFF:
 339                 return quota_setxstate(sb, cmd, addr);
 340         case Q_XQUOTARM:
 341                 return quota_rmxquota(sb, addr);
 342         case Q_XGETQSTAT:
 343                 return quota_getxstate(sb, addr);
 344         case Q_XGETQSTATV:
 345                 return quota_getxstatev(sb, addr);
 346         case Q_XSETQLIM:
 347                 return quota_setxquota(sb, type, id, addr);
 348         case Q_XGETQUOTA:
 349                 return quota_getxquota(sb, type, id, addr);
 350         case Q_XQUOTASYNC:
 351                 if (sb->s_flags & MS_RDONLY)
 352                         return -EROFS;
 353                 /* XFS quotas are fully coherent now, making this call a noop */
 354                 return 0;
 355         default:
 356                 return -EINVAL;
 357         }
 358 }
 359
 360 #ifdef CONFIG_BLOCK
 361
 362 /* Return 1 if 'cmd' will block on frozen filesystem */
 363 static int quotactl_cmd_write(int cmd)
 364 {
 365         switch (cmd) {
 366         case Q_GETFMT:
 367         case Q_GETINFO:
 368         case Q_SYNC:
 369         case Q_XGETQSTAT:
 370         case Q_XGETQSTATV:
 371         case Q_XGETQUOTA:
 372         case Q_XQUOTASYNC:
 373                 return 0;
 374         }
 375         return 1;
 376 }
 377
 378 #endif /* CONFIG_BLOCK */
 379
 380 /*
 381  * look up a superblock on which quota ops will be performed
 382  * - use the name of a block device to find the superblock thereon
 383  */
 384 static struct super_block *quotactl_block(const char __user *special, int cmd)
 385 {
 386 #ifdef CONFIG_BLOCK
 387         struct block_device *bdev;
 388         struct super_block *sb;
 389         struct filename *tmp = getname(special);
 390
 391         if (IS_ERR(tmp))
 392                 return ERR_CAST(tmp);
 393         bdev = lookup_bdev(tmp->name);
 394         putname(tmp);
 395         if (IS_ERR(bdev))
 396                 return ERR_CAST(bdev);
 397         if (quotactl_cmd_write(cmd))
 398                 sb = get_super_thawed(bdev);
 399         else
 400                 sb = get_super(bdev);
 401         bdput(bdev);
 402         if (!sb)
 403                 return ERR_PTR(-ENODEV);
 404
 405         return sb;
 406 #else
 407         return ERR_PTR(-ENODEV);
 408 #endif
 409 }
 410
 411 /*
 412  * This is the system call interface. This communicates with
 413  * the user-level programs. Currently this only supports diskquota
 414  * calls. Maybe we need to add the process quotas etc. in the future,
 415  * but we probably should use rlimits for that.
 416  */
 417 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 418                 qid_t, id, void __user *, addr)
 419 {
 420         uint cmds, type;
 421         struct super_block *sb = NULL;
 422         struct path path, *pathp = NULL;
 423         int ret;
 424
 425         cmds = cmd >> SUBCMDSHIFT;
 426         type = cmd & SUBCMDMASK;
 427
 428         /*
 429          * As a special case Q_SYNC can be called without a specific device.
 430          * It will iterate all superblocks that have quota enabled and call
 431          * the sync action on each of them.
 432          */
 433         if (!special) {
 434                 if (cmds == Q_SYNC)
 435                         return quota_sync_all(type);
 436                 return -ENODEV;
 437         }
 438
 439         /*
 440          * Path for quotaon has to be resolved before grabbing superblock
 441          * because that gets s_umount sem which is also possibly needed by path
 442          * resolution (think about autofs) and thus deadlocks could arise.
 443          */
 444         if (cmds == Q_QUOTAON) {
 445                 ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
 446                 if (ret)
 447                         pathp = ERR_PTR(ret);
 448                 else
 449                         pathp = &path;
 450         }
 451
 452         sb = quotactl_block(special, cmds);
 453         if (IS_ERR(sb)) {
 454                 ret = PTR_ERR(sb);
 455                 goto out;
 456         }
 457
 458         ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 459
 460         drop_super(sb);
 461 out:
 462         if (pathp && !IS_ERR(pathp))
 463                 path_put(pathp);
 464         return ret;
 465 }