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