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