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