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 <linux/uaccess.h>
  13 #include <linux/kernel.h>
  14 #include <linux/security.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/capability.h>
  17 #include <linux/quotaops.h>
  18 #include <linux/types.h>
  19 #include <linux/writeback.h>
  20
  21 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  22                                      qid_t id)
  23 {
  24         switch (cmd) {
  25         /* these commands do not require any special privilegues */
  26         case Q_GETFMT:
  27         case Q_SYNC:
  28         case Q_GETINFO:
  29         case Q_XGETQSTAT:
  30         case Q_XQUOTASYNC:
  31                 break;
  32         /* allow to query information for dquots we "own" */
  33         case Q_GETQUOTA:
  34         case Q_XGETQUOTA:
  35                 if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
  36                     (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
  37                         break;
  38                 /*FALLTHROUGH*/
  39         default:
  40                 if (!capable(CAP_SYS_ADMIN))
  41                         return -EPERM;
  42         }
  43
  44         return security_quotactl(cmd, type, id, sb);
  45 }
  46
  47 static void quota_sync_one(struct super_block *sb, void *arg)
  48 {
  49         if (sb->s_qcop && sb->s_qcop->quota_sync)
  50                 sb->s_qcop->quota_sync(sb, *(int *)arg);
  51 }
  52
  53 static int quota_sync_all(int type)
  54 {
  55         int ret;
  56
  57         if (type >= MAXQUOTAS)
  58                 return -EINVAL;
  59         ret = security_quotactl(Q_SYNC, type, 0, NULL);
  60         if (!ret)
  61                 iterate_supers(quota_sync_one, &type);
  62         return ret;
  63 }
  64
  65 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
  66                          struct path *path)
  67 {
  68         if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
  69                 return -ENOSYS;
  70         if (sb->s_qcop->quota_on_meta)
  71                 return sb->s_qcop->quota_on_meta(sb, type, id);
  72         if (IS_ERR(path))
  73                 return PTR_ERR(path);
  74         return sb->s_qcop->quota_on(sb, type, id, path);
  75 }
  76
  77 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
  78 {
  79         __u32 fmt;
  80
  81         down_read(&sb_dqopt(sb)->dqptr_sem);
  82         if (!sb_has_quota_active(sb, type)) {
  83                 up_read(&sb_dqopt(sb)->dqptr_sem);
  84                 return -ESRCH;
  85         }
  86         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
  87         up_read(&sb_dqopt(sb)->dqptr_sem);
  88         if (copy_to_user(addr, &fmt, sizeof(fmt)))
  89                 return -EFAULT;
  90         return 0;
  91 }
  92
  93 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
  94 {
  95         struct if_dqinfo info;
  96         int ret;
  97
  98         if (!sb->s_qcop->get_info)
  99                 return -ENOSYS;
 100         ret = sb->s_qcop->get_info(sb, type, &info);
 101         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 102                 return -EFAULT;
 103         return ret;
 104 }
 105
 106 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 107 {
 108         struct if_dqinfo info;
 109
 110         if (copy_from_user(&info, addr, sizeof(info)))
 111                 return -EFAULT;
 112         if (!sb->s_qcop->set_info)
 113                 return -ENOSYS;
 114         return sb->s_qcop->set_info(sb, type, &info);
 115 }
 116
 117 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 118 {
 119         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 120         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 121         dst->dqb_curspace = src->d_bcount;
 122         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 123         dst->dqb_isoftlimit = src->d_ino_softlimit;
 124         dst->dqb_curinodes = src->d_icount;
 125         dst->dqb_btime = src->d_btimer;
 126         dst->dqb_itime = src->d_itimer;
 127         dst->dqb_valid = QIF_ALL;
 128 }
 129
 130 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 131                           void __user *addr)
 132 {
 133         struct kqid qid;
 134         struct fs_disk_quota fdq;
 135         struct if_dqblk idq;
 136         int ret;
 137
 138         if (!sb->s_qcop->get_dqblk)
 139                 return -ENOSYS;
 140         qid = make_kqid(current_user_ns(), type, id);
 141         if (!qid_valid(qid))
 142                 return -EINVAL;
 143         ret = sb->s_qcop->get_dqblk(sb, qid, &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         struct kqid qid;
 184
 185         if (copy_from_user(&idq, addr, sizeof(idq)))
 186                 return -EFAULT;
 187         if (!sb->s_qcop->set_dqblk)
 188                 return -ENOSYS;
 189         qid = make_kqid(current_user_ns(), type, id);
 190         if (!qid_valid(qid))
 191                 return -EINVAL;
 192         copy_from_if_dqblk(&fdq, &idq);
 193         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 194 }
 195
 196 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 197 {
 198         __u32 flags;
 199
 200         if (copy_from_user(&flags, addr, sizeof(flags)))
 201                 return -EFAULT;
 202         if (!sb->s_qcop->set_xstate)
 203                 return -ENOSYS;
 204         return sb->s_qcop->set_xstate(sb, flags, cmd);
 205 }
 206
 207 static int quota_getxstate(struct super_block *sb, void __user *addr)
 208 {
 209         struct fs_quota_stat fqs;
 210         int ret;
 211
 212         if (!sb->s_qcop->get_xstate)
 213                 return -ENOSYS;
 214         ret = sb->s_qcop->get_xstate(sb, &fqs);
 215         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 216                 return -EFAULT;
 217         return ret;
 218 }
 219
 220 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 221                            void __user *addr)
 222 {
 223         struct fs_disk_quota fdq;
 224         struct kqid qid;
 225
 226         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 227                 return -EFAULT;
 228         if (!sb->s_qcop->set_dqblk)
 229                 return -ENOSYS;
 230         qid = make_kqid(current_user_ns(), type, id);
 231         if (!qid_valid(qid))
 232                 return -EINVAL;
 233         return sb->s_qcop->set_dqblk(sb, qid, &fdq);
 234 }
 235
 236 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 237                            void __user *addr)
 238 {
 239         struct fs_disk_quota fdq;
 240         struct kqid qid;
 241         int ret;
 242
 243         if (!sb->s_qcop->get_dqblk)
 244                 return -ENOSYS;
 245         qid = make_kqid(current_user_ns(), type, id);
 246         if (!qid_valid(qid))
 247                 return -EINVAL;
 248         ret = sb->s_qcop->get_dqblk(sb, qid, &fdq);
 249         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 250                 return -EFAULT;
 251         return ret;
 252 }
 253
 254 /* Copy parameters and call proper function */
 255 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 256                        void __user *addr, struct path *path)
 257 {
 258         int ret;
 259
 260         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 261                 return -EINVAL;
 262         if (!sb->s_qcop)
 263                 return -ENOSYS;
 264
 265         ret = check_quotactl_permission(sb, type, cmd, id);
 266         if (ret < 0)
 267                 return ret;
 268
 269         switch (cmd) {
 270         case Q_QUOTAON:
 271                 return quota_quotaon(sb, type, cmd, id, path);
 272         case Q_QUOTAOFF:
 273                 if (!sb->s_qcop->quota_off)
 274                         return -ENOSYS;
 275                 return sb->s_qcop->quota_off(sb, type);
 276         case Q_GETFMT:
 277                 return quota_getfmt(sb, type, addr);
 278         case Q_GETINFO:
 279                 return quota_getinfo(sb, type, addr);
 280         case Q_SETINFO:
 281                 return quota_setinfo(sb, type, addr);
 282         case Q_GETQUOTA:
 283                 return quota_getquota(sb, type, id, addr);
 284         case Q_SETQUOTA:
 285                 return quota_setquota(sb, type, id, addr);
 286         case Q_SYNC:
 287                 if (!sb->s_qcop->quota_sync)
 288                         return -ENOSYS;
 289                 return sb->s_qcop->quota_sync(sb, type);
 290         case Q_XQUOTAON:
 291         case Q_XQUOTAOFF:
 292         case Q_XQUOTARM:
 293                 return quota_setxstate(sb, cmd, addr);
 294         case Q_XGETQSTAT:
 295                 return quota_getxstate(sb, addr);
 296         case Q_XSETQLIM:
 297                 return quota_setxquota(sb, type, id, addr);
 298         case Q_XGETQUOTA:
 299                 return quota_getxquota(sb, type, id, addr);
 300         case Q_XQUOTASYNC:
 301                 if (sb->s_flags & MS_RDONLY)
 302                         return -EROFS;
 303                 /* XFS quotas are fully coherent now, making this call a noop */
 304                 return 0;
 305         default:
 306                 return -EINVAL;
 307         }
 308 }
 309
 310 /* Return 1 if 'cmd' will block on frozen filesystem */
 311 static int quotactl_cmd_write(int cmd)
 312 {
 313         switch (cmd) {
 314         case Q_GETFMT:
 315         case Q_GETINFO:
 316         case Q_SYNC:
 317         case Q_XGETQSTAT:
 318         case Q_XGETQUOTA:
 319         case Q_XQUOTASYNC:
 320                 return 0;
 321         }
 322         return 1;
 323 }
 324
 325 /*
 326  * look up a superblock on which quota ops will be performed
 327  * - use the name of a block device to find the superblock thereon
 328  */
 329 static struct super_block *quotactl_block(const char __user *special, int cmd)
 330 {
 331 #ifdef CONFIG_BLOCK
 332         struct block_device *bdev;
 333         struct super_block *sb;
 334         struct filename *tmp = getname(special);
 335
 336         if (IS_ERR(tmp))
 337                 return ERR_CAST(tmp);
 338         bdev = lookup_bdev(tmp->name);
 339         putname(tmp);
 340         if (IS_ERR(bdev))
 341                 return ERR_CAST(bdev);
 342         if (quotactl_cmd_write(cmd))
 343                 sb = get_super_thawed(bdev);
 344         else
 345                 sb = get_super(bdev);
 346         bdput(bdev);
 347         if (!sb)
 348                 return ERR_PTR(-ENODEV);
 349
 350         return sb;
 351 #else
 352         return ERR_PTR(-ENODEV);
 353 #endif
 354 }
 355
 356 /*
 357  * This is the system call interface. This communicates with
 358  * the user-level programs. Currently this only supports diskquota
 359  * calls. Maybe we need to add the process quotas etc. in the future,
 360  * but we probably should use rlimits for that.
 361  */
 362 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 363                 qid_t, id, void __user *, addr)
 364 {
 365         uint cmds, type;
 366         struct super_block *sb = NULL;
 367         struct path path, *pathp = NULL;
 368         int ret;
 369
 370         cmds = cmd >> SUBCMDSHIFT;
 371         type = cmd & SUBCMDMASK;
 372
 373         /*
 374          * As a special case Q_SYNC can be called without a specific device.
 375          * It will iterate all superblocks that have quota enabled and call
 376          * the sync action on each of them.
 377          */
 378         if (!special) {
 379                 if (cmds == Q_SYNC)
 380                         return quota_sync_all(type);
 381                 return -ENODEV;
 382         }
 383
 384         /*
 385          * Path for quotaon has to be resolved before grabbing superblock
 386          * because that gets s_umount sem which is also possibly needed by path
 387          * resolution (think about autofs) and thus deadlocks could arise.
 388          */
 389         if (cmds == Q_QUOTAON) {
 390                 ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
 391                 if (ret)
 392                         pathp = ERR_PTR(ret);
 393                 else
 394                         pathp = &path;
 395         }
 396
 397         sb = quotactl_block(special, cmds);
 398         if (IS_ERR(sb)) {
 399                 ret = PTR_ERR(sb);
 400                 goto out;
 401         }
 402
 403         ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 404
 405         drop_super(sb);
 406 out:
 407         if (pathp && !IS_ERR(pathp))
 408                 path_put(pathp);
 409         return ret;
 410 }