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, *n;
  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         list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
  61                 if (list_empty(&sb->s_instances))
  62                         continue;
  63                 if (!sb->s_qcop || !sb->s_qcop->quota_sync)
  64                         continue;
  65
  66                 sb->s_count++;
  67                 spin_unlock(&sb_lock);
  68                 down_read(&sb->s_umount);
  69                 if (sb->s_root)
  70                         sb->s_qcop->quota_sync(sb, type, 1);
  71                 up_read(&sb->s_umount);
  72                 spin_lock(&sb_lock);
  73                 __put_super(sb);
  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->s_qcop->get_info)
 117                 return -ENOSYS;
 118         ret = sb->s_qcop->get_info(sb, type, &info);
 119         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 120                 return -EFAULT;
 121         return ret;
 122 }
 123
 124 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 125 {
 126         struct if_dqinfo info;
 127
 128         if (copy_from_user(&info, addr, sizeof(info)))
 129                 return -EFAULT;
 130         if (!sb->s_qcop->set_info)
 131                 return -ENOSYS;
 132         return sb->s_qcop->set_info(sb, type, &info);
 133 }
 134
 135 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 136 {
 137         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 138         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 139         dst->dqb_curspace = src->d_bcount;
 140         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 141         dst->dqb_isoftlimit = src->d_ino_softlimit;
 142         dst->dqb_curinodes = src->d_icount;
 143         dst->dqb_btime = src->d_btimer;
 144         dst->dqb_itime = src->d_itimer;
 145         dst->dqb_valid = QIF_ALL;
 146 }
 147
 148 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 149                           void __user *addr)
 150 {
 151         struct fs_disk_quota fdq;
 152         struct if_dqblk idq;
 153         int ret;
 154
 155         if (!sb->s_qcop->get_dqblk)
 156                 return -ENOSYS;
 157         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 158         if (ret)
 159                 return ret;
 160         copy_to_if_dqblk(&idq, &fdq);
 161         if (copy_to_user(addr, &idq, sizeof(idq)))
 162                 return -EFAULT;
 163         return 0;
 164 }
 165
 166 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
 167 {
 168         dst->d_blk_hardlimit = src->dqb_bhardlimit;
 169         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
 170         dst->d_bcount = src->dqb_curspace;
 171         dst->d_ino_hardlimit = src->dqb_ihardlimit;
 172         dst->d_ino_softlimit = src->dqb_isoftlimit;
 173         dst->d_icount = src->dqb_curinodes;
 174         dst->d_btimer = src->dqb_btime;
 175         dst->d_itimer = src->dqb_itime;
 176
 177         dst->d_fieldmask = 0;
 178         if (src->dqb_valid & QIF_BLIMITS)
 179                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
 180         if (src->dqb_valid & QIF_SPACE)
 181                 dst->d_fieldmask |= FS_DQ_BCOUNT;
 182         if (src->dqb_valid & QIF_ILIMITS)
 183                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
 184         if (src->dqb_valid & QIF_INODES)
 185                 dst->d_fieldmask |= FS_DQ_ICOUNT;
 186         if (src->dqb_valid & QIF_BTIME)
 187                 dst->d_fieldmask |= FS_DQ_BTIMER;
 188         if (src->dqb_valid & QIF_ITIME)
 189                 dst->d_fieldmask |= FS_DQ_ITIMER;
 190 }
 191
 192 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 193                           void __user *addr)
 194 {
 195         struct fs_disk_quota fdq;
 196         struct if_dqblk idq;
 197
 198         if (copy_from_user(&idq, addr, sizeof(idq)))
 199                 return -EFAULT;
 200         if (!sb->s_qcop->set_dqblk)
 201                 return -ENOSYS;
 202         copy_from_if_dqblk(&fdq, &idq);
 203         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 204 }
 205
 206 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 207 {
 208         __u32 flags;
 209
 210         if (copy_from_user(&flags, addr, sizeof(flags)))
 211                 return -EFAULT;
 212         if (!sb->s_qcop->set_xstate)
 213                 return -ENOSYS;
 214         return sb->s_qcop->set_xstate(sb, flags, cmd);
 215 }
 216
 217 static int quota_getxstate(struct super_block *sb, void __user *addr)
 218 {
 219         struct fs_quota_stat fqs;
 220         int ret;
 221
 222         if (!sb->s_qcop->get_xstate)
 223                 return -ENOSYS;
 224         ret = sb->s_qcop->get_xstate(sb, &fqs);
 225         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 226                 return -EFAULT;
 227         return ret;
 228 }
 229
 230 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 231                            void __user *addr)
 232 {
 233         struct fs_disk_quota fdq;
 234
 235         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 236                 return -EFAULT;
 237         if (!sb->s_qcop->set_dqblk)
 238                 return -ENOSYS;
 239         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 240 }
 241
 242 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 243                            void __user *addr)
 244 {
 245         struct fs_disk_quota fdq;
 246         int ret;
 247
 248         if (!sb->s_qcop->get_dqblk)
 249                 return -ENOSYS;
 250         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 251         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 252                 return -EFAULT;
 253         return ret;
 254 }
 255
 256 /* Copy parameters and call proper function */
 257 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 258                        void __user *addr)
 259 {
 260         int ret;
 261
 262         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 263                 return -EINVAL;
 264         if (!sb->s_qcop)
 265                 return -ENOSYS;
 266
 267         ret = check_quotactl_permission(sb, type, cmd, id);
 268         if (ret < 0)
 269                 return ret;
 270
 271         switch (cmd) {
 272         case Q_QUOTAON:
 273                 return quota_quotaon(sb, type, cmd, id, addr);
 274         case Q_QUOTAOFF:
 275                 if (!sb->s_qcop->quota_off)
 276                         return -ENOSYS;
 277                 return sb->s_qcop->quota_off(sb, type, 0);
 278         case Q_GETFMT:
 279                 return quota_getfmt(sb, type, addr);
 280         case Q_GETINFO:
 281                 return quota_getinfo(sb, type, addr);
 282         case Q_SETINFO:
 283                 return quota_setinfo(sb, type, addr);
 284         case Q_GETQUOTA:
 285                 return quota_getquota(sb, type, id, addr);
 286         case Q_SETQUOTA:
 287                 return quota_setquota(sb, type, id, addr);
 288         case Q_SYNC:
 289                 if (!sb->s_qcop->quota_sync)
 290                         return -ENOSYS;
 291                 return sb->s_qcop->quota_sync(sb, type, 1);
 292         case Q_XQUOTAON:
 293         case Q_XQUOTAOFF:
 294         case Q_XQUOTARM:
 295                 return quota_setxstate(sb, cmd, addr);
 296         case Q_XGETQSTAT:
 297                 return quota_getxstate(sb, addr);
 298         case Q_XSETQLIM:
 299                 return quota_setxquota(sb, type, id, addr);
 300         case Q_XGETQUOTA:
 301                 return quota_getxquota(sb, type, id, addr);
 302         case Q_XQUOTASYNC:
 303                 /* caller already holds s_umount */
 304                 if (sb->s_flags & MS_RDONLY)
 305                         return -EROFS;
 306                 writeback_inodes_sb(sb);
 307                 return 0;
 308         default:
 309                 return -EINVAL;
 310         }
 311 }
 312
 313 /*
 314  * look up a superblock on which quota ops will be performed
 315  * - use the name of a block device to find the superblock thereon
 316  */
 317 static struct super_block *quotactl_block(const char __user *special)
 318 {
 319 #ifdef CONFIG_BLOCK
 320         struct block_device *bdev;
 321         struct super_block *sb;
 322         char *tmp = getname(special);
 323
 324         if (IS_ERR(tmp))
 325                 return ERR_CAST(tmp);
 326         bdev = lookup_bdev(tmp);
 327         putname(tmp);
 328         if (IS_ERR(bdev))
 329                 return ERR_CAST(bdev);
 330         sb = get_super(bdev);
 331         bdput(bdev);
 332         if (!sb)
 333                 return ERR_PTR(-ENODEV);
 334
 335         return sb;
 336 #else
 337         return ERR_PTR(-ENODEV);
 338 #endif
 339 }
 340
 341 /*
 342  * This is the system call interface. This communicates with
 343  * the user-level programs. Currently this only supports diskquota
 344  * calls. Maybe we need to add the process quotas etc. in the future,
 345  * but we probably should use rlimits for that.
 346  */
 347 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 348                 qid_t, id, void __user *, addr)
 349 {
 350         uint cmds, type;
 351         struct super_block *sb = 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         sb = quotactl_block(special);
 369         if (IS_ERR(sb))
 370                 return PTR_ERR(sb);
 371
 372         ret = do_quotactl(sb, type, cmds, id, addr);
 373
 374         drop_super(sb);
 375         return ret;
 376 }