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