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 #include "../internal.h"
  22
  23 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
  24                                      qid_t id)
  25 {
  26         switch (cmd) {
  27         /* these commands do not require any special privilegues */
  28         case Q_GETFMT:
  29         case Q_SYNC:
  30         case Q_GETINFO:
  31         case Q_XGETQSTAT:
  32         case Q_XQUOTASYNC:
  33                 break;
  34         /* allow to query information for dquots we "own" */
  35         case Q_GETQUOTA:
  36         case Q_XGETQUOTA:
  37                 if ((type == USRQUOTA && current_euid() == id) ||
  38                     (type == GRPQUOTA && in_egroup_p(id)))
  39                         break;
  40                 /*FALLTHROUGH*/
  41         default:
  42                 if (!capable(CAP_SYS_ADMIN))
  43                         return -EPERM;
  44         }
  45
  46         return security_quotactl(cmd, type, id, sb);
  47 }
  48
  49 static int quota_sync_all(int type)
  50 {
  51         struct super_block *sb, *n;
  52         int ret;
  53
  54         if (type >= MAXQUOTAS)
  55                 return -EINVAL;
  56         ret = security_quotactl(Q_SYNC, type, 0, NULL);
  57         if (ret)
  58                 return ret;
  59
  60         spin_lock(&sb_lock);
  61         list_for_each_entry_safe(sb, n, &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                 __put_super(sb);
  75         }
  76         spin_unlock(&sb_lock);
  77
  78         return 0;
  79 }
  80
  81 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
  82                          void __user *addr)
  83 {
  84         char *pathname;
  85         int ret = -ENOSYS;
  86
  87         pathname = getname(addr);
  88         if (IS_ERR(pathname))
  89                 return PTR_ERR(pathname);
  90         if (sb->s_qcop->quota_on)
  91                 ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
  92         putname(pathname);
  93         return ret;
  94 }
  95
  96 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
  97 {
  98         __u32 fmt;
  99
 100         down_read(&sb_dqopt(sb)->dqptr_sem);
 101         if (!sb_has_quota_active(sb, type)) {
 102                 up_read(&sb_dqopt(sb)->dqptr_sem);
 103                 return -ESRCH;
 104         }
 105         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
 106         up_read(&sb_dqopt(sb)->dqptr_sem);
 107         if (copy_to_user(addr, &fmt, sizeof(fmt)))
 108                 return -EFAULT;
 109         return 0;
 110 }
 111
 112 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
 113 {
 114         struct if_dqinfo info;
 115         int ret;
 116
 117         if (!sb->s_qcop->get_info)
 118                 return -ENOSYS;
 119         ret = sb->s_qcop->get_info(sb, type, &info);
 120         if (!ret && copy_to_user(addr, &info, sizeof(info)))
 121                 return -EFAULT;
 122         return ret;
 123 }
 124
 125 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
 126 {
 127         struct if_dqinfo info;
 128
 129         if (copy_from_user(&info, addr, sizeof(info)))
 130                 return -EFAULT;
 131         if (!sb->s_qcop->set_info)
 132                 return -ENOSYS;
 133         return sb->s_qcop->set_info(sb, type, &info);
 134 }
 135
 136 static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
 137 {
 138         dst->dqb_bhardlimit = src->d_blk_hardlimit;
 139         dst->dqb_bsoftlimit = src->d_blk_softlimit;
 140         dst->dqb_curspace = src->d_bcount;
 141         dst->dqb_ihardlimit = src->d_ino_hardlimit;
 142         dst->dqb_isoftlimit = src->d_ino_softlimit;
 143         dst->dqb_curinodes = src->d_icount;
 144         dst->dqb_btime = src->d_btimer;
 145         dst->dqb_itime = src->d_itimer;
 146         dst->dqb_valid = QIF_ALL;
 147 }
 148
 149 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 150                           void __user *addr)
 151 {
 152         struct fs_disk_quota fdq;
 153         struct if_dqblk idq;
 154         int ret;
 155
 156         if (!sb->s_qcop->get_dqblk)
 157                 return -ENOSYS;
 158         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 159         if (ret)
 160                 return ret;
 161         copy_to_if_dqblk(&idq, &fdq);
 162         if (copy_to_user(addr, &idq, sizeof(idq)))
 163                 return -EFAULT;
 164         return 0;
 165 }
 166
 167 static void copy_from_if_dqblk(struct fs_disk_quota *dst, struct if_dqblk *src)
 168 {
 169         dst->d_blk_hardlimit = src->dqb_bhardlimit;
 170         dst->d_blk_softlimit  = src->dqb_bsoftlimit;
 171         dst->d_bcount = src->dqb_curspace;
 172         dst->d_ino_hardlimit = src->dqb_ihardlimit;
 173         dst->d_ino_softlimit = src->dqb_isoftlimit;
 174         dst->d_icount = src->dqb_curinodes;
 175         dst->d_btimer = src->dqb_btime;
 176         dst->d_itimer = src->dqb_itime;
 177
 178         dst->d_fieldmask = 0;
 179         if (src->dqb_valid & QIF_BLIMITS)
 180                 dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
 181         if (src->dqb_valid & QIF_SPACE)
 182                 dst->d_fieldmask |= FS_DQ_BCOUNT;
 183         if (src->dqb_valid & QIF_ILIMITS)
 184                 dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
 185         if (src->dqb_valid & QIF_INODES)
 186                 dst->d_fieldmask |= FS_DQ_ICOUNT;
 187         if (src->dqb_valid & QIF_BTIME)
 188                 dst->d_fieldmask |= FS_DQ_BTIMER;
 189         if (src->dqb_valid & QIF_ITIME)
 190                 dst->d_fieldmask |= FS_DQ_ITIMER;
 191 }
 192
 193 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 194                           void __user *addr)
 195 {
 196         struct fs_disk_quota fdq;
 197         struct if_dqblk idq;
 198
 199         if (copy_from_user(&idq, addr, sizeof(idq)))
 200                 return -EFAULT;
 201         if (!sb->s_qcop->set_dqblk)
 202                 return -ENOSYS;
 203         copy_from_if_dqblk(&fdq, &idq);
 204         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 205 }
 206
 207 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 208 {
 209         __u32 flags;
 210
 211         if (copy_from_user(&flags, addr, sizeof(flags)))
 212                 return -EFAULT;
 213         if (!sb->s_qcop->set_xstate)
 214                 return -ENOSYS;
 215         return sb->s_qcop->set_xstate(sb, flags, cmd);
 216 }
 217
 218 static int quota_getxstate(struct super_block *sb, void __user *addr)
 219 {
 220         struct fs_quota_stat fqs;
 221         int ret;
 222
 223         if (!sb->s_qcop->get_xstate)
 224                 return -ENOSYS;
 225         ret = sb->s_qcop->get_xstate(sb, &fqs);
 226         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 227                 return -EFAULT;
 228         return ret;
 229 }
 230
 231 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 232                            void __user *addr)
 233 {
 234         struct fs_disk_quota fdq;
 235
 236         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 237                 return -EFAULT;
 238         if (!sb->s_qcop->set_dqblk)
 239                 return -ENOSYS;
 240         return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
 241 }
 242
 243 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 244                            void __user *addr)
 245 {
 246         struct fs_disk_quota fdq;
 247         int ret;
 248
 249         if (!sb->s_qcop->get_dqblk)
 250                 return -ENOSYS;
 251         ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
 252         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 253                 return -EFAULT;
 254         return ret;
 255 }
 256
 257 /* Copy parameters and call proper function */
 258 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 259                        void __user *addr)
 260 {
 261         int ret;
 262
 263         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 264                 return -EINVAL;
 265         if (!sb->s_qcop)
 266                 return -ENOSYS;
 267
 268         ret = check_quotactl_permission(sb, type, cmd, id);
 269         if (ret < 0)
 270                 return ret;
 271
 272         switch (cmd) {
 273         case Q_QUOTAON:
 274                 return quota_quotaon(sb, type, cmd, id, addr);
 275         case Q_QUOTAOFF:
 276                 if (!sb->s_qcop->quota_off)
 277                         return -ENOSYS;
 278                 return sb->s_qcop->quota_off(sb, type, 0);
 279         case Q_GETFMT:
 280                 return quota_getfmt(sb, type, addr);
 281         case Q_GETINFO:
 282                 return quota_getinfo(sb, type, addr);
 283         case Q_SETINFO:
 284                 return quota_setinfo(sb, type, addr);
 285         case Q_GETQUOTA:
 286                 return quota_getquota(sb, type, id, addr);
 287         case Q_SETQUOTA:
 288                 return quota_setquota(sb, type, id, addr);
 289         case Q_SYNC:
 290                 if (!sb->s_qcop->quota_sync)
 291                         return -ENOSYS;
 292                 return sb->s_qcop->quota_sync(sb, type, 1);
 293         case Q_XQUOTAON:
 294         case Q_XQUOTAOFF:
 295         case Q_XQUOTARM:
 296                 return quota_setxstate(sb, cmd, addr);
 297         case Q_XGETQSTAT:
 298                 return quota_getxstate(sb, addr);
 299         case Q_XSETQLIM:
 300                 return quota_setxquota(sb, type, id, addr);
 301         case Q_XGETQUOTA:
 302                 return quota_getxquota(sb, type, id, addr);
 303         case Q_XQUOTASYNC:
 304                 /* caller already holds s_umount */
 305                 if (sb->s_flags & MS_RDONLY)
 306                         return -EROFS;
 307                 writeback_inodes_sb(sb);
 308                 return 0;
 309         default:
 310                 return -EINVAL;
 311         }
 312 }
 313
 314 /*
 315  * look up a superblock on which quota ops will be performed
 316  * - use the name of a block device to find the superblock thereon
 317  */
 318 static struct super_block *quotactl_block(const char __user *special)
 319 {
 320 #ifdef CONFIG_BLOCK
 321         struct block_device *bdev;
 322         struct super_block *sb;
 323         char *tmp = getname(special);
 324
 325         if (IS_ERR(tmp))
 326                 return ERR_CAST(tmp);
 327         bdev = lookup_bdev(tmp);
 328         putname(tmp);
 329         if (IS_ERR(bdev))
 330                 return ERR_CAST(bdev);
 331         sb = get_super(bdev);
 332         bdput(bdev);
 333         if (!sb)
 334                 return ERR_PTR(-ENODEV);
 335
 336         return sb;
 337 #else
 338         return ERR_PTR(-ENODEV);
 339 #endif
 340 }
 341
 342 /*
 343  * This is the system call interface. This communicates with
 344  * the user-level programs. Currently this only supports diskquota
 345  * calls. Maybe we need to add the process quotas etc. in the future,
 346  * but we probably should use rlimits for that.
 347  */
 348 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 349                 qid_t, id, void __user *, addr)
 350 {
 351         uint cmds, type;
 352         struct super_block *sb = NULL;
 353         int ret;
 354
 355         cmds = cmd >> SUBCMDSHIFT;
 356         type = cmd & SUBCMDMASK;
 357
 358         /*
 359          * As a special case Q_SYNC can be called without a specific device.
 360          * It will iterate all superblocks that have quota enabled and call
 361          * the sync action on each of them.
 362          */
 363         if (!special) {
 364                 if (cmds == Q_SYNC)
 365                         return quota_sync_all(type);
 366                 return -ENODEV;
 367         }
 368
 369         sb = quotactl_block(special);
 370         if (IS_ERR(sb))
 371                 return PTR_ERR(sb);
 372
 373         ret = do_quotactl(sb, type, cmds, id, addr);
 374
 375         drop_super(sb);
 376         return ret;
 377 }