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 <asm/uaccess.h>
  13 #include <linux/compat.h>
  14 #include <linux/kernel.h>
  15 #include <linux/security.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/buffer_head.h>
  18 #include <linux/capability.h>
  19 #include <linux/quotaops.h>
  20 #include <linux/types.h>
  21 #include <linux/writeback.h>
  22 #include <net/netlink.h>
  23 #include <net/genetlink.h>
  24
  25 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  26                                      qid_t id)
  27 {
  28         switch (cmd) {
  29         /* these commands do not require any special privilegues */
  30         case Q_GETFMT:
  31         case Q_SYNC:
  32         case Q_GETINFO:
  33         case Q_XGETQSTAT:
  34         case Q_XQUOTASYNC:
  35                 break;
  36         /* allow to query information for dquots we "own" */
  37         case Q_GETQUOTA:
  38         case Q_XGETQUOTA:
  39                 if ((type == USRQUOTA && current_euid() == id) ||
  40                     (type == GRPQUOTA && in_egroup_p(id)))
  41                         break;
  42                 /*FALLTHROUGH*/
  43         default:
  44                 if (!capable(CAP_SYS_ADMIN))
  45                         return -EPERM;
  46         }
  47
  48         return security_quotactl(cmd, type, id, sb);
  49 }
  50
  51 #ifdef CONFIG_QUOTA
  52 void sync_quota_sb(struct super_block *sb, int type)
  53 {
  54         int cnt;
  55
  56         if (!sb->s_qcop || !sb->s_qcop->quota_sync)
  57                 return;
  58
  59         sb->s_qcop->quota_sync(sb, type);
  60
  61         if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
  62                 return;
  63         /* This is not very clever (and fast) but currently I don't know about
  64          * any other simple way of getting quota data to disk and we must get
  65          * them there for userspace to be visible... */
  66         if (sb->s_op->sync_fs)
  67                 sb->s_op->sync_fs(sb, 1);
  68         sync_blockdev(sb->s_bdev);
  69
  70         /*
  71          * Now when everything is written we can discard the pagecache so
  72          * that userspace sees the changes.
  73          */
  74         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
  75         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  76                 if (type != -1 && cnt != type)
  77                         continue;
  78                 if (!sb_has_quota_active(sb, cnt))
  79                         continue;
  80                 mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex,
  81                                   I_MUTEX_QUOTA);
  82                 truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
  83                 mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
  84         }
  85         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
  86 }
  87 #endif
  88
  89 static int quota_sync_all(int type)
  90 {
  91         struct super_block *sb;
  92         int cnt;
  93         int ret;
  94
  95         if (type >= MAXQUOTAS)
  96                 return -EINVAL;
  97         ret = security_quotactl(Q_SYNC, type, 0, NULL);
  98         if (ret)
  99                 return ret;
 100
 101         spin_lock(&sb_lock);
 102 restart:
 103         list_for_each_entry(sb, &super_blocks, s_list) {
 104                 /* This test just improves performance so it needn't be
 105                  * reliable... */
 106                 for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 107                         if (type != -1 && type != cnt)
 108                                 continue;
 109                         if (!sb_has_quota_active(sb, cnt))
 110                                 continue;
 111                         if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
 112                            list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
 113                                 continue;
 114                         break;
 115                 }
 116                 if (cnt == MAXQUOTAS)
 117                         continue;
 118                 sb->s_count++;
 119                 spin_unlock(&sb_lock);
 120                 down_read(&sb->s_umount);
 121                 if (sb->s_root)
 122                         sync_quota_sb(sb, type);
 123                 up_read(&sb->s_umount);
 124                 spin_lock(&sb_lock);
 125                 if (__put_super_and_need_restart(sb))
 126                         goto restart;
 127         }
 128         spin_unlock(&sb_lock);
 129
 130         return 0;
 131 }
 132
 133 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
 134                          void __user *addr)
 135 {
 136         char *pathname;
 137         int ret = -ENOSYS;
 138
 139         pathname = getname(addr);
 140         if (IS_ERR(pathname))
 141                 return PTR_ERR(pathname);
 142         if (sb->s_qcop->quota_on)
 143                 ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
 144         putname(pathname);
 145         return ret;
 146 }
 147
 148 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
 149 {
 150         __u32 fmt;
 151
 152         down_read(&sb_dqopt(sb)->dqptr_sem);
 153         if (!sb_has_quota_active(sb, type)) {
 154                 up_read(&sb_dqopt(sb)->dqptr_sem);
 155                 return -ESRCH;
 156         }
 157         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 158         up_read(&sb_dqopt(sb)->dqptr_sem);
 159         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 160                 return -EFAULT;
 161         return 0;
 162 }
 163
 164 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
 165 {
 166         struct if_dqinfo info;
 167         int ret;
 168
 169         if (!sb_has_quota_active(sb, type))
 170                 return -ESRCH;
 171         if (!sb->s_qcop->get_info)
 172                 return -ENOSYS;
 173         ret = sb->s_qcop->get_info(sb, type, &info);
 174         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 175                 return -EFAULT;
 176         return ret;
 177 }
 178
 179 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 180 {
 181         struct if_dqinfo info;
 182
 183         if (copy_from_user(&info, addr, sizeof(info)))
 184                 return -EFAULT;
 185         if (!sb_has_quota_active(sb, type))
 186                 return -ESRCH;
 187         if (!sb->s_qcop->set_info)
 188                 return -ENOSYS;
 189         return sb->s_qcop->set_info(sb, type, &info);
 190 }
 191
 192 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 193                           void __user *addr)
 194 {
 195         struct if_dqblk idq;
 196         int ret;
 197
 198         if (!sb_has_quota_active(sb, type))
 199                 return -ESRCH;
 200         if (!sb->s_qcop->get_dqblk)
 201                 return -ENOSYS;
 202         ret = sb->s_qcop->get_dqblk(sb, type, id, &idq);
 203         if (ret)
 204                 return ret;
 205         if (copy_to_user(addr, &idq, sizeof(idq)))
 206                 return -EFAULT;
 207         return 0;
 208 }
 209
 210 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 211                           void __user *addr)
 212 {
 213         struct if_dqblk idq;
 214
 215         if (copy_from_user(&idq, addr, sizeof(idq)))
 216                 return -EFAULT;
 217         if (!sb_has_quota_active(sb, type))
 218                 return -ESRCH;
 219         if (!sb->s_qcop->set_dqblk)
 220                 return -ENOSYS;
 221         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 222 }
 223
 224 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 225 {
 226         __u32 flags;
 227
 228         if (copy_from_user(&flags, addr, sizeof(flags)))
 229                 return -EFAULT;
 230         if (!sb->s_qcop->set_xstate)
 231                 return -ENOSYS;
 232         return sb->s_qcop->set_xstate(sb, flags, cmd);
 233 }
 234
 235 static int quota_getxstate(struct super_block *sb, void __user *addr)
 236 {
 237         struct fs_quota_stat fqs;
 238         int ret;
 239
 240         if (!sb->s_qcop->get_xstate)
 241                 return -ENOSYS;
 242         ret = sb->s_qcop->get_xstate(sb, &fqs);
 243         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 244                 return -EFAULT;
 245         return ret;
 246 }
 247
 248 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 249                            void __user *addr)
 250 {
 251         struct fs_disk_quota fdq;
 252
 253         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 254                 return -EFAULT;
 255         if (!sb->s_qcop->set_xquota)
 256                 return -ENOSYS;
 257         return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 258 }
 259
 260 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 261                            void __user *addr)
 262 {
 263         struct fs_disk_quota fdq;
 264         int ret;
 265
 266         if (!sb->s_qcop->get_xquota)
 267                 return -ENOSYS;
 268         ret = sb->s_qcop->get_xquota(sb, type, id, &fdq);
 269         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 270                 return -EFAULT;
 271         return ret;
 272 }
 273
 274 /* Copy parameters and call proper function */
 275 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 276                        void __user *addr)
 277 {
 278         int ret;
 279
 280         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 281                 return -EINVAL;
 282         if (!sb->s_qcop)
 283                 return -ENOSYS;
 284
 285         ret = check_quotactl_permission(sb, type, cmd, id);
 286         if (ret < 0)
 287                 return ret;
 288
 289         switch (cmd) {
 290         case Q_QUOTAON:
 291                 return quota_quotaon(sb, type, cmd, id, addr);
 292         case Q_QUOTAOFF:
 293                 if (!sb->s_qcop->quota_off)
 294                         return -ENOSYS;
 295                 return sb->s_qcop->quota_off(sb, type, 0);
 296         case Q_GETFMT:
 297                 return quota_getfmt(sb, type, addr);
 298         case Q_GETINFO:
 299                 return quota_getinfo(sb, type, addr);
 300         case Q_SETINFO:
 301                 return quota_setinfo(sb, type, addr);
 302         case Q_GETQUOTA:
 303                 return quota_getquota(sb, type, id, addr);
 304         case Q_SETQUOTA:
 305                 return quota_setquota(sb, type, id, addr);
 306         case Q_SYNC:
 307                 if (!sb->s_qcop->quota_sync)
 308                         return -ENOSYS;
 309                 sync_quota_sb(sb, type);
 310                 return 0;
 311         case Q_XQUOTAON:
 312         case Q_XQUOTAOFF:
 313         case Q_XQUOTARM:
 314                 return quota_setxstate(sb, cmd, addr);
 315         case Q_XGETQSTAT:
 316                 return quota_getxstate(sb, addr);
 317         case Q_XSETQLIM:
 318                 return quota_setxquota(sb, type, id, addr);
 319         case Q_XGETQUOTA:
 320                 return quota_getxquota(sb, type, id, addr);
 321         case Q_XQUOTASYNC:
 322                 /* caller already holds s_umount */
 323                 if (sb->s_flags & MS_RDONLY)
 324                         return -EROFS;
 325                 writeback_inodes_sb(sb);
 326                 return 0;
 327         default:
 328                 return -EINVAL;
 329         }
 330 }
 331
 332 /*
 333  * look up a superblock on which quota ops will be performed
 334  * - use the name of a block device to find the superblock thereon
 335  */
 336 static struct super_block *quotactl_block(const char __user *special)
 337 {
 338 #ifdef CONFIG_BLOCK
 339         struct block_device *bdev;
 340         struct super_block *sb;
 341         char *tmp = getname(special);
 342
 343         if (IS_ERR(tmp))
 344                 return ERR_CAST(tmp);
 345         bdev = lookup_bdev(tmp);
 346         putname(tmp);
 347         if (IS_ERR(bdev))
 348                 return ERR_CAST(bdev);
 349         sb = get_super(bdev);
 350         bdput(bdev);
 351         if (!sb)
 352                 return ERR_PTR(-ENODEV);
 353
 354         return sb;
 355 #else
 356         return ERR_PTR(-ENODEV);
 357 #endif
 358 }
 359
 360 /*
 361  * This is the system call interface. This communicates with
 362  * the user-level programs. Currently this only supports diskquota
 363  * calls. Maybe we need to add the process quotas etc. in the future,
 364  * but we probably should use rlimits for that.
 365  */
 366 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 367                 qid_t, id, void __user *, addr)
 368 {
 369         uint cmds, type;
 370         struct super_block *sb = NULL;
 371         int ret;
 372
 373         cmds = cmd >> SUBCMDSHIFT;
 374         type = cmd & SUBCMDMASK;
 375
 376         /*
 377          * As a special case Q_SYNC can be called without a specific device.
 378          * It will iterate all superblocks that have quota enabled and call
 379          * the sync action on each of them.
 380          */
 381         if (!special) {
 382                 if (cmds == Q_SYNC)
 383                         return quota_sync_all(type);
 384                 return -ENODEV;
 385         }
 386
 387         sb = quotactl_block(special);
 388         if (IS_ERR(sb))
 389                 return PTR_ERR(sb);
 390
 391         ret = do_quotactl(sb, type, cmds, id, addr);
 392
 393         drop_super(sb);
 394         return ret;
 395 }
 396
 397 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
 398 /*
 399  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
 400  * and is necessary due to alignment problems.
 401  */
 402 struct compat_if_dqblk {
 403         compat_u64 dqb_bhardlimit;
 404         compat_u64 dqb_bsoftlimit;
 405         compat_u64 dqb_curspace;
 406         compat_u64 dqb_ihardlimit;
 407         compat_u64 dqb_isoftlimit;
 408         compat_u64 dqb_curinodes;
 409         compat_u64 dqb_btime;
 410         compat_u64 dqb_itime;
 411         compat_uint_t dqb_valid;
 412 };
 413
 414 /* XFS structures */
 415 struct compat_fs_qfilestat {
 416         compat_u64 dqb_bhardlimit;
 417         compat_u64 qfs_nblks;
 418         compat_uint_t qfs_nextents;
 419 };
 420
 421 struct compat_fs_quota_stat {
 422         __s8            qs_version;
 423         __u16           qs_flags;
 424         __s8            qs_pad;
 425         struct compat_fs_qfilestat      qs_uquota;
 426         struct compat_fs_qfilestat      qs_gquota;
 427         compat_uint_t   qs_incoredqs;
 428         compat_int_t    qs_btimelimit;
 429         compat_int_t    qs_itimelimit;
 430         compat_int_t    qs_rtbtimelimit;
 431         __u16           qs_bwarnlimit;
 432         __u16           qs_iwarnlimit;
 433 };
 434
 435 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
 436                                                 qid_t id, void __user *addr)
 437 {
 438         unsigned int cmds;
 439         struct if_dqblk __user *dqblk;
 440         struct compat_if_dqblk __user *compat_dqblk;
 441         struct fs_quota_stat __user *fsqstat;
 442         struct compat_fs_quota_stat __user *compat_fsqstat;
 443         compat_uint_t data;
 444         u16 xdata;
 445         long ret;
 446
 447         cmds = cmd >> SUBCMDSHIFT;
 448
 449         switch (cmds) {
 450         case Q_GETQUOTA:
 451                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 452                 compat_dqblk = addr;
 453                 ret = sys_quotactl(cmd, special, id, dqblk);
 454                 if (ret)
 455                         break;
 456                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
 457                         get_user(data, &dqblk->dqb_valid) ||
 458                         put_user(data, &compat_dqblk->dqb_valid))
 459                         ret = -EFAULT;
 460                 break;
 461         case Q_SETQUOTA:
 462                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
 463                 compat_dqblk = addr;
 464                 ret = -EFAULT;
 465                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
 466                         get_user(data, &compat_dqblk->dqb_valid) ||
 467                         put_user(data, &dqblk->dqb_valid))
 468                         break;
 469                 ret = sys_quotactl(cmd, special, id, dqblk);
 470                 break;
 471         case Q_XGETQSTAT:
 472                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
 473                 compat_fsqstat = addr;
 474                 ret = sys_quotactl(cmd, special, id, fsqstat);
 475                 if (ret)
 476                         break;
 477                 ret = -EFAULT;
 478                 /* Copying qs_version, qs_flags, qs_pad */
 479                 if (copy_in_user(compat_fsqstat, fsqstat,
 480                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
 481                         break;
 482                 /* Copying qs_uquota */
 483                 if (copy_in_user(&compat_fsqstat->qs_uquota,
 484                         &fsqstat->qs_uquota,
 485                         sizeof(compat_fsqstat->qs_uquota)) ||
 486                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
 487                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
 488                         break;
 489                 /* Copying qs_gquota */
 490                 if (copy_in_user(&compat_fsqstat->qs_gquota,
 491                         &fsqstat->qs_gquota,
 492                         sizeof(compat_fsqstat->qs_gquota)) ||
 493                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
 494                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
 495                         break;
 496                 /* Copying the rest */
 497                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
 498                         &fsqstat->qs_incoredqs,
 499                         sizeof(struct compat_fs_quota_stat) -
 500                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
 501                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
 502                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
 503                         break;
 504                 ret = 0;
 505                 break;
 506         default:
 507                 ret = sys_quotactl(cmd, special, id, addr);
 508         }
 509         return ret;
 510 }
 511 #endif
 512
 513
 514 #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
 515
 516 /* Netlink family structure for quota */
 517 static struct genl_family quota_genl_family = {
 518         .id = GENL_ID_GENERATE,
 519         .hdrsize = 0,
 520         .name = "VFS_DQUOT",
 521         .version = 1,
 522         .maxattr = QUOTA_NL_A_MAX,
 523 };
 524
 525 /**
 526  * quota_send_warning - Send warning to userspace about exceeded quota
 527  * @type: The quota type: USRQQUOTA, GRPQUOTA,...
 528  * @id: The user or group id of the quota that was exceeded
 529  * @dev: The device on which the fs is mounted (sb->s_dev)
 530  * @warntype: The type of the warning: QUOTA_NL_...
 531  *
 532  * This can be used by filesystems (including those which don't use
 533  * dquot) to send a message to userspace relating to quota limits.
 534  *
 535  */
 536
 537 void quota_send_warning(short type, unsigned int id, dev_t dev,
 538                         const char warntype)
 539 {
 540         static atomic_t seq;
 541         struct sk_buff *skb;
 542         void *msg_head;
 543         int ret;
 544         int msg_size = 4 * nla_total_size(sizeof(u32)) +
 545                        2 * nla_total_size(sizeof(u64));
 546
 547         /* We have to allocate using GFP_NOFS as we are called from a
 548          * filesystem performing write and thus further recursion into
 549          * the fs to free some data could cause deadlocks. */
 550         skb = genlmsg_new(msg_size, GFP_NOFS);
 551         if (!skb) {
 552                 printk(KERN_ERR
 553                   "VFS: Not enough memory to send quota warning.\n");
 554                 return;
 555         }
 556         msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
 557                         &quota_genl_family, 0, QUOTA_NL_C_WARNING);
 558         if (!msg_head) {
 559                 printk(KERN_ERR
 560                   "VFS: Cannot store netlink header in quota warning.\n");
 561                 goto err_out;
 562         }
 563         ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
 564         if (ret)
 565                 goto attr_err_out;
 566         ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
 567         if (ret)
 568                 goto attr_err_out;
 569         ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
 570         if (ret)
 571                 goto attr_err_out;
 572         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
 573         if (ret)
 574                 goto attr_err_out;
 575         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
 576         if (ret)
 577                 goto attr_err_out;
 578         ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
 579         if (ret)
 580                 goto attr_err_out;
 581         genlmsg_end(skb, msg_head);
 582
 583         genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
 584         return;
 585 attr_err_out:
 586         printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
 587 err_out:
 588         kfree_skb(skb);
 589 }
 590 EXPORT_SYMBOL(quota_send_warning);
 591
 592 static int __init quota_init(void)
 593 {
 594         if (genl_register_family(&quota_genl_family) != 0)
 595                 printk(KERN_ERR
 596                        "VFS: Failed to create quota netlink interface.\n");
 597         return 0;
 598 };
 599
 600 module_init(quota_init);
 601 #endif
 602