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/buffer_head.h>
  17 #include <linux/capability.h>
  18 #include <linux/quotaops.h>
  19 #include <linux/types.h>
  20 #include <linux/writeback.h>
  21
  22 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  23                                      qid_t id)
  24 {
  25         switch (cmd) {
  26         /* these commands do not require any special privilegues */
  27         case Q_GETFMT:
  28         case Q_SYNC:
  29         case Q_GETINFO:
  30         case Q_XGETQSTAT:
  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 && current_euid() == id) ||
  37                     (type == GRPQUOTA && in_egroup_p(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, 1);
  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         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 121         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 122         dst->dqb_curspace = src->d_bcount;
 123         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 124         dst->dqb_isoftlimit = src->d_ino_softlimit;
 125         dst->dqb_curinodes = src->d_icount;
 126         dst->dqb_btime = src->d_btimer;
 127         dst->dqb_itime = src->d_itimer;
 128         dst->dqb_valid = QIF_ALL;
 129 }
 130
 131 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 132                           void __user *addr)
 133 {
 134         struct fs_disk_quota fdq;
 135         struct if_dqblk idq;
 136         int ret;
 137
 138         if (!sb->s_qcop->get_dqblk)
 139                 return -ENOSYS;
 140         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 141         if (ret)
 142                 return ret;
 143         copy_to_if_dqblk(&idq, &fdq);
 144         if (copy_to_user(addr, &idq, sizeof(idq)))
 145                 return -EFAULT;
 146         return 0;
 147 }
 148
 149 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
 150 {
 151         dst->d_blk_hardlimit = src->dqb_bhardlimit;
 152         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
 153         dst->d_bcount = src->dqb_curspace;
 154         dst->d_ino_hardlimit = src->dqb_ihardlimit;
 155         dst->d_ino_softlimit = src->dqb_isoftlimit;
 156         dst->d_icount = src->dqb_curinodes;
 157         dst->d_btimer = src->dqb_btime;
 158         dst->d_itimer = src->dqb_itime;
 159
 160         dst->d_fieldmask = 0;
 161         if (src->dqb_valid & QIF_BLIMITS)
 162                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
 163         if (src->dqb_valid & QIF_SPACE)
 164                 dst->d_fieldmask |= FS_DQ_BCOUNT;
 165         if (src->dqb_valid & QIF_ILIMITS)
 166                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
 167         if (src->dqb_valid & QIF_INODES)
 168                 dst->d_fieldmask |= FS_DQ_ICOUNT;
 169         if (src->dqb_valid & QIF_BTIME)
 170                 dst->d_fieldmask |= FS_DQ_BTIMER;
 171         if (src->dqb_valid & QIF_ITIME)
 172                 dst->d_fieldmask |= FS_DQ_ITIMER;
 173 }
 174
 175 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 176                           void __user *addr)
 177 {
 178         struct fs_disk_quota fdq;
 179         struct if_dqblk idq;
 180
 181         if (copy_from_user(&idq, addr, sizeof(idq)))
 182                 return -EFAULT;
 183         if (!sb->s_qcop->set_dqblk)
 184                 return -ENOSYS;
 185         copy_from_if_dqblk(&fdq, &idq);
 186         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 187 }
 188
 189 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 190 {
 191         __u32 flags;
 192
 193         if (copy_from_user(&flags, addr, sizeof(flags)))
 194                 return -EFAULT;
 195         if (!sb->s_qcop->set_xstate)
 196                 return -ENOSYS;
 197         return sb->s_qcop->set_xstate(sb, flags, cmd);
 198 }
 199
 200 static int quota_getxstate(struct super_block *sb, void __user *addr)
 201 {
 202         struct fs_quota_stat fqs;
 203         int ret;
 204
 205         if (!sb->s_qcop->get_xstate)
 206                 return -ENOSYS;
 207         ret = sb->s_qcop->get_xstate(sb, &fqs);
 208         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 209                 return -EFAULT;
 210         return ret;
 211 }
 212
 213 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 214                            void __user *addr)
 215 {
 216         struct fs_disk_quota fdq;
 217
 218         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 219                 return -EFAULT;
 220         if (!sb->s_qcop->set_dqblk)
 221                 return -ENOSYS;
 222         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 223 }
 224
 225 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 226                            void __user *addr)
 227 {
 228         struct fs_disk_quota fdq;
 229         int ret;
 230
 231         if (!sb->s_qcop->get_dqblk)
 232                 return -ENOSYS;
 233         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 234         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 235                 return -EFAULT;
 236         return ret;
 237 }
 238
 239 /* Copy parameters and call proper function */
 240 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 241                        void __user *addr, struct path *path)
 242 {
 243         int ret;
 244
 245         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 246                 return -EINVAL;
 247         if (!sb->s_qcop)
 248                 return -ENOSYS;
 249
 250         ret = check_quotactl_permission(sb, type, cmd, id);
 251         if (ret < 0)
 252                 return ret;
 253
 254         switch (cmd) {
 255         case Q_QUOTAON:
 256                 return quota_quotaon(sb, type, cmd, id, path);
 257         case Q_QUOTAOFF:
 258                 if (!sb->s_qcop->quota_off)
 259                         return -ENOSYS;
 260                 return sb->s_qcop->quota_off(sb, type);
 261         case Q_GETFMT:
 262                 return quota_getfmt(sb, type, addr);
 263         case Q_GETINFO:
 264                 return quota_getinfo(sb, type, addr);
 265         case Q_SETINFO:
 266                 return quota_setinfo(sb, type, addr);
 267         case Q_GETQUOTA:
 268                 return quota_getquota(sb, type, id, addr);
 269         case Q_SETQUOTA:
 270                 return quota_setquota(sb, type, id, addr);
 271         case Q_SYNC:
 272                 if (!sb->s_qcop->quota_sync)
 273                         return -ENOSYS;
 274                 return sb->s_qcop->quota_sync(sb, type, 1);
 275         case Q_XQUOTAON:
 276         case Q_XQUOTAOFF:
 277         case Q_XQUOTARM:
 278                 return quota_setxstate(sb, cmd, addr);
 279         case Q_XGETQSTAT:
 280                 return quota_getxstate(sb, addr);
 281         case Q_XSETQLIM:
 282                 return quota_setxquota(sb, type, id, addr);
 283         case Q_XGETQUOTA:
 284                 return quota_getxquota(sb, type, id, addr);
 285         case Q_XQUOTASYNC:
 286                 /* caller already holds s_umount */
 287                 if (sb->s_flags & MS_RDONLY)
 288                         return -EROFS;
 289                 writeback_inodes_sb(sb);
 290                 return 0;
 291         default:
 292                 return -EINVAL;
 293         }
 294 }
 295
 296 /*
 297  * look up a superblock on which quota ops will be performed
 298  * - use the name of a block device to find the superblock thereon
 299  */
 300 static struct super_block *quotactl_block(const char __user *special)
 301 {
 302 #ifdef CONFIG_BLOCK
 303         struct block_device *bdev;
 304         struct super_block *sb;
 305         char *tmp = getname(special);
 306
 307         if (IS_ERR(tmp))
 308                 return ERR_CAST(tmp);
 309         bdev = lookup_bdev(tmp);
 310         putname(tmp);
 311         if (IS_ERR(bdev))
 312                 return ERR_CAST(bdev);
 313         sb = get_super(bdev);
 314         bdput(bdev);
 315         if (!sb)
 316                 return ERR_PTR(-ENODEV);
 317
 318         return sb;
 319 #else
 320         return ERR_PTR(-ENODEV);
 321 #endif
 322 }
 323
 324 /*
 325  * This is the system call interface. This communicates with
 326  * the user-level programs. Currently this only supports diskquota
 327  * calls. Maybe we need to add the process quotas etc. in the future,
 328  * but we probably should use rlimits for that.
 329  */
 330 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 331                 qid_t, id, void __user *, addr)
 332 {
 333         uint cmds, type;
 334         struct super_block *sb = NULL;
 335         struct path path, *pathp = NULL;
 336         int ret;
 337
 338         cmds = cmd >> SUBCMDSHIFT;
 339         type = cmd & SUBCMDMASK;
 340
 341         /*
 342          * As a special case Q_SYNC can be called without a specific device.
 343          * It will iterate all superblocks that have quota enabled and call
 344          * the sync action on each of them.
 345          */
 346         if (!special) {
 347                 if (cmds == Q_SYNC)
 348                         return quota_sync_all(type);
 349                 return -ENODEV;
 350         }
 351
 352         /*
 353          * Path for quotaon has to be resolved before grabbing superblock
 354          * because that gets s_umount sem which is also possibly needed by path
 355          * resolution (think about autofs) and thus deadlocks could arise.
 356          */
 357         if (cmds == Q_QUOTAON) {
 358                 ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW, &path);
 359                 if (ret)
 360                         pathp = ERR_PTR(ret);
 361                 else
 362                         pathp = &path;
 363         }
 364
 365         sb = quotactl_block(special);
 366         if (IS_ERR(sb))
 367                 return PTR_ERR(sb);
 368
 369         ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 370
 371         drop_super(sb);
 372         if (pathp && !IS_ERR(pathp))
 373                 path_put(pathp);
 374         return ret;
 375 }