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 (!sb->s_qcop || !sb->s_qcop->quota_sync)
  63                         continue;
  64
  65                 sb->s_count++;
  66                 spin_unlock(&sb_lock);
  67                 down_read(&sb->s_umount);
  68                 if (sb->s_root)
  69                         sb->s_qcop->quota_sync(sb, type, 1);
  70                 up_read(&sb->s_umount);
  71                 spin_lock(&sb_lock);
  72                 if (__put_super_and_need_restart(sb))
  73                         goto restart;
  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_has_quota_active(sb, type))
 117                 return -ESRCH;
 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_has_quota_active(sb, type))
 133                 return -ESRCH;
 134         if (!sb->s_qcop->set_info)
 135                 return -ENOSYS;
 136         return sb->s_qcop->set_info(sb, type, &info);
 137 }
 138
 139 static int quota_getquota(struct super_block *sb, int type, qid_t id,
 140                           void __user *addr)
 141 {
 142         struct if_dqblk idq;
 143         int ret;
 144
 145         if (!sb_has_quota_active(sb, type))
 146                 return -ESRCH;
 147         if (!sb->s_qcop->get_dqblk)
 148                 return -ENOSYS;
 149         ret = sb->s_qcop->get_dqblk(sb, type, id, &idq);
 150         if (ret)
 151                 return ret;
 152         if (copy_to_user(addr, &idq, sizeof(idq)))
 153                 return -EFAULT;
 154         return 0;
 155 }
 156
 157 static int quota_setquota(struct super_block *sb, int type, qid_t id,
 158                           void __user *addr)
 159 {
 160         struct if_dqblk idq;
 161
 162         if (copy_from_user(&idq, addr, sizeof(idq)))
 163                 return -EFAULT;
 164         if (!sb_has_quota_active(sb, type))
 165                 return -ESRCH;
 166         if (!sb->s_qcop->set_dqblk)
 167                 return -ENOSYS;
 168         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
 169 }
 170
 171 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
 172 {
 173         __u32 flags;
 174
 175         if (copy_from_user(&flags, addr, sizeof(flags)))
 176                 return -EFAULT;
 177         if (!sb->s_qcop->set_xstate)
 178                 return -ENOSYS;
 179         return sb->s_qcop->set_xstate(sb, flags, cmd);
 180 }
 181
 182 static int quota_getxstate(struct super_block *sb, void __user *addr)
 183 {
 184         struct fs_quota_stat fqs;
 185         int ret;
 186
 187         if (!sb->s_qcop->get_xstate)
 188                 return -ENOSYS;
 189         ret = sb->s_qcop->get_xstate(sb, &fqs);
 190         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
 191                 return -EFAULT;
 192         return ret;
 193 }
 194
 195 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
 196                            void __user *addr)
 197 {
 198         struct fs_disk_quota fdq;
 199
 200         if (copy_from_user(&fdq, addr, sizeof(fdq)))
 201                 return -EFAULT;
 202         if (!sb->s_qcop->set_xquota)
 203                 return -ENOSYS;
 204         return sb->s_qcop->set_xquota(sb, type, id, &fdq);
 205 }
 206
 207 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 208                            void __user *addr)
 209 {
 210         struct fs_disk_quota fdq;
 211         int ret;
 212
 213         if (!sb->s_qcop->get_xquota)
 214                 return -ENOSYS;
 215         ret = sb->s_qcop->get_xquota(sb, type, id, &fdq);
 216         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
 217                 return -EFAULT;
 218         return ret;
 219 }
 220
 221 /* Copy parameters and call proper function */
 222 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 223                        void __user *addr)
 224 {
 225         int ret;
 226
 227         if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
 228                 return -EINVAL;
 229         if (!sb->s_qcop)
 230                 return -ENOSYS;
 231
 232         ret = check_quotactl_permission(sb, type, cmd, id);
 233         if (ret < 0)
 234                 return ret;
 235
 236         switch (cmd) {
 237         case Q_QUOTAON:
 238                 return quota_quotaon(sb, type, cmd, id, addr);
 239         case Q_QUOTAOFF:
 240                 if (!sb->s_qcop->quota_off)
 241                         return -ENOSYS;
 242                 return sb->s_qcop->quota_off(sb, type, 0);
 243         case Q_GETFMT:
 244                 return quota_getfmt(sb, type, addr);
 245         case Q_GETINFO:
 246                 return quota_getinfo(sb, type, addr);
 247         case Q_SETINFO:
 248                 return quota_setinfo(sb, type, addr);
 249         case Q_GETQUOTA:
 250                 return quota_getquota(sb, type, id, addr);
 251         case Q_SETQUOTA:
 252                 return quota_setquota(sb, type, id, addr);
 253         case Q_SYNC:
 254                 if (!sb->s_qcop->quota_sync)
 255                         return -ENOSYS;
 256                 return sb->s_qcop->quota_sync(sb, type, 1);
 257         case Q_XQUOTAON:
 258         case Q_XQUOTAOFF:
 259         case Q_XQUOTARM:
 260                 return quota_setxstate(sb, cmd, addr);
 261         case Q_XGETQSTAT:
 262                 return quota_getxstate(sb, addr);
 263         case Q_XSETQLIM:
 264                 return quota_setxquota(sb, type, id, addr);
 265         case Q_XGETQUOTA:
 266                 return quota_getxquota(sb, type, id, addr);
 267         case Q_XQUOTASYNC:
 268                 /* caller already holds s_umount */
 269                 if (sb->s_flags & MS_RDONLY)
 270                         return -EROFS;
 271                 writeback_inodes_sb(sb);
 272                 return 0;
 273         default:
 274                 return -EINVAL;
 275         }
 276 }
 277
 278 /*
 279  * look up a superblock on which quota ops will be performed
 280  * - use the name of a block device to find the superblock thereon
 281  */
 282 static struct super_block *quotactl_block(const char __user *special)
 283 {
 284 #ifdef CONFIG_BLOCK
 285         struct block_device *bdev;
 286         struct super_block *sb;
 287         char *tmp = getname(special);
 288
 289         if (IS_ERR(tmp))
 290                 return ERR_CAST(tmp);
 291         bdev = lookup_bdev(tmp);
 292         putname(tmp);
 293         if (IS_ERR(bdev))
 294                 return ERR_CAST(bdev);
 295         sb = get_super(bdev);
 296         bdput(bdev);
 297         if (!sb)
 298                 return ERR_PTR(-ENODEV);
 299
 300         return sb;
 301 #else
 302         return ERR_PTR(-ENODEV);
 303 #endif
 304 }
 305
 306 /*
 307  * This is the system call interface. This communicates with
 308  * the user-level programs. Currently this only supports diskquota
 309  * calls. Maybe we need to add the process quotas etc. in the future,
 310  * but we probably should use rlimits for that.
 311  */
 312 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 313                 qid_t, id, void __user *, addr)
 314 {
 315         uint cmds, type;
 316         struct super_block *sb = NULL;
 317         int ret;
 318
 319         cmds = cmd >> SUBCMDSHIFT;
 320         type = cmd & SUBCMDMASK;
 321
 322         /*
 323          * As a special case Q_SYNC can be called without a specific device.
 324          * It will iterate all superblocks that have quota enabled and call
 325          * the sync action on each of them.
 326          */
 327         if (!special) {
 328                 if (cmds == Q_SYNC)
 329                         return quota_sync_all(type);
 330                 return -ENODEV;
 331         }
 332
 333         sb = quotactl_block(special);
 334         if (IS_ERR(sb))
 335                 return PTR_ERR(sb);
 336
 337         ret = do_quotactl(sb, type, cmds, id, addr);
 338
 339         drop_super(sb);
 340         return ret;
 341 }