fs/statfs.c

   1 #include <linux/syscalls.h>
   2 #include <linux/module.h>
   3 #include <linux/fs.h>
   4 #include <linux/file.h>
   5 #include <linux/mount.h>
   6 #include <linux/namei.h>
   7 #include <linux/statfs.h>
   8 #include <linux/security.h>
   9 #include <linux/uaccess.h>
  10
  11 static int flags_by_mnt(int mnt_flags)
  12 {
  13         int flags = 0;
  14
  15         if (mnt_flags & MNT_READONLY)
  16                 flags |= ST_RDONLY;
  17         if (mnt_flags & MNT_NOSUID)
  18                 flags |= ST_NOSUID;
  19         if (mnt_flags & MNT_NODEV)
  20                 flags |= ST_NODEV;
  21         if (mnt_flags & MNT_NOEXEC)
  22                 flags |= ST_NOEXEC;
  23         if (mnt_flags & MNT_NOATIME)
  24                 flags |= ST_NOATIME;
  25         if (mnt_flags & MNT_NODIRATIME)
  26                 flags |= ST_NODIRATIME;
  27         if (mnt_flags & MNT_RELATIME)
  28                 flags |= ST_RELATIME;
  29         return flags;
  30 }
  31
  32 static int flags_by_sb(int s_flags)
  33 {
  34         int flags = 0;
  35         if (s_flags & MS_SYNCHRONOUS)
  36                 flags |= ST_SYNCHRONOUS;
  37         if (s_flags & MS_MANDLOCK)
  38                 flags |= ST_MANDLOCK;
  39         return flags;
  40 }
  41
  42 static int calculate_f_flags(struct vfsmount *mnt)
  43 {
  44         return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
  45                 flags_by_sb(mnt->mnt_sb->s_flags);
  46 }
  47
  48 int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
  49 {
  50         int retval;
  51
  52         if (!dentry->d_sb->s_op->statfs)
  53                 return -ENOSYS;
  54
  55         memset(buf, 0, sizeof(*buf));
  56         retval = security_sb_statfs(dentry);
  57         if (retval)
  58                 return retval;
  59         retval = dentry->d_sb->s_op->statfs(dentry, buf);
  60         if (retval == 0 && buf->f_frsize == 0)
  61                 buf->f_frsize = buf->f_bsize;
  62         return retval;
  63 }
  64
  65 int vfs_statfs(struct path *path, struct kstatfs *buf)
  66 {
  67         int error;
  68
  69         error = statfs_by_dentry(path->dentry, buf);
  70         if (!error)
  71                 buf->f_flags = calculate_f_flags(path->mnt);
  72         return error;
  73 }
  74 EXPORT_SYMBOL(vfs_statfs);
  75
  76 int user_statfs(const char __user *pathname, struct kstatfs *st)
  77 {
  78         struct path path;
  79         int error = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
  80         if (!error) {
  81                 error = vfs_statfs(&path, st);
  82                 path_put(&path);
  83         }
  84         return error;
  85 }
  86
  87 int fd_statfs(int fd, struct kstatfs *st)
  88 {
  89         struct file *file = fget(fd);
  90         int error = -EBADF;
  91         if (file) {
  92                 error = vfs_statfs(&file->f_path, st);
  93                 fput(file);
  94         }
  95         return error;
  96 }
  97
  98 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
  99 {
 100         struct statfs buf;
 101
 102         if (sizeof(buf) == sizeof(*st))
 103                 memcpy(&buf, st, sizeof(*st));
 104         else {
 105                 if (sizeof buf.f_blocks == 4) {
 106                         if ((st->f_blocks | st->f_bfree | st->f_bavail |
 107                              st->f_bsize | st->f_frsize) &
 108                             0xffffffff00000000ULL)
 109                                 return -EOVERFLOW;
 110                         /*
 111                          * f_files and f_ffree may be -1; it's okay to stuff
 112                          * that into 32 bits
 113                          */
 114                         if (st->f_files != -1 &&
 115                             (st->f_files & 0xffffffff00000000ULL))
 116                                 return -EOVERFLOW;
 117                         if (st->f_ffree != -1 &&
 118                             (st->f_ffree & 0xffffffff00000000ULL))
 119                                 return -EOVERFLOW;
 120                 }
 121
 122                 buf.f_type = st->f_type;
 123                 buf.f_bsize = st->f_bsize;
 124                 buf.f_blocks = st->f_blocks;
 125                 buf.f_bfree = st->f_bfree;
 126                 buf.f_bavail = st->f_bavail;
 127                 buf.f_files = st->f_files;
 128                 buf.f_ffree = st->f_ffree;
 129                 buf.f_fsid = st->f_fsid;
 130                 buf.f_namelen = st->f_namelen;
 131                 buf.f_frsize = st->f_frsize;
 132                 buf.f_flags = st->f_flags;
 133                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 134         }
 135         if (copy_to_user(p, &buf, sizeof(buf)))
 136                 return -EFAULT;
 137         return 0;
 138 }
 139
 140 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 141 {
 142         struct statfs64 buf;
 143         if (sizeof(buf) == sizeof(*st))
 144                 memcpy(&buf, st, sizeof(*st));
 145         else {
 146                 buf.f_type = st->f_type;
 147                 buf.f_bsize = st->f_bsize;
 148                 buf.f_blocks = st->f_blocks;
 149                 buf.f_bfree = st->f_bfree;
 150                 buf.f_bavail = st->f_bavail;
 151                 buf.f_files = st->f_files;
 152                 buf.f_ffree = st->f_ffree;
 153                 buf.f_fsid = st->f_fsid;
 154                 buf.f_namelen = st->f_namelen;
 155                 buf.f_frsize = st->f_frsize;
 156                 buf.f_flags = st->f_flags;
 157                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 158         }
 159         if (copy_to_user(p, &buf, sizeof(buf)))
 160                 return -EFAULT;
 161         return 0;
 162 }
 163
 164 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 165 {
 166         struct kstatfs st;
 167         int error = user_statfs(pathname, &st);
 168         if (!error)
 169                 error = do_statfs_native(&st, buf);
 170         return error;
 171 }
 172
 173 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 174 {
 175         struct kstatfs st;
 176         int error;
 177         if (sz != sizeof(*buf))
 178                 return -EINVAL;
 179         error = user_statfs(pathname, &st);
 180         if (!error)
 181                 error = do_statfs64(&st, buf);
 182         return error;
 183 }
 184
 185 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 186 {
 187         struct kstatfs st;
 188         int error = fd_statfs(fd, &st);
 189         if (!error)
 190                 error = do_statfs_native(&st, buf);
 191         return error;
 192 }
 193
 194 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 195 {
 196         struct kstatfs st;
 197         int error;
 198
 199         if (sz != sizeof(*buf))
 200                 return -EINVAL;
 201
 202         error = fd_statfs(fd, &st);
 203         if (!error)
 204                 error = do_statfs64(&st, buf);
 205         return error;
 206 }
 207
 208 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 209 {
 210         struct super_block *s;
 211         struct ustat tmp;
 212         struct kstatfs sbuf;
 213         int err;
 214
 215         s = user_get_super(new_decode_dev(dev));
 216         if (!s)
 217                 return -EINVAL;
 218
 219         err = statfs_by_dentry(s->s_root, &sbuf);
 220         drop_super(s);
 221         if (err)
 222                 return err;
 223
 224         memset(&tmp,0,sizeof(struct ustat));
 225         tmp.f_tfree = sbuf.f_bfree;
 226         tmp.f_tinode = sbuf.f_ffree;
 227
 228         return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 229 }