LXR linux/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
  22static 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
  48static 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
  54static 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
  66static 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
  81static 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
  97static 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
 110static 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
 121static 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
 134static 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
 152static 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
 178static 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
 192static 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
 203static 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
 216static 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
 228static 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 */
 243static 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 */
 303static 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 */
 333SYSCALL_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}
 363