fs/statfs.c

   1 #include <linux/syscalls.h>
   2 #include <linux/export.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 #include "internal.h"
  11
  12 static int flags_by_mnt(int mnt_flags)
  13 {
  14         int flags = 0;
  15
  16         if (mnt_flags & MNT_READONLY)
  17                 flags |= ST_RDONLY;
  18         if (mnt_flags & MNT_NOSUID)
  19                 flags |= ST_NOSUID;
  20         if (mnt_flags & MNT_NODEV)
  21                 flags |= ST_NODEV;
  22         if (mnt_flags & MNT_NOEXEC)
  23                 flags |= ST_NOEXEC;
  24         if (mnt_flags & MNT_NOATIME)
  25                 flags |= ST_NOATIME;
  26         if (mnt_flags & MNT_NODIRATIME)
  27                 flags |= ST_NODIRATIME;
  28         if (mnt_flags & MNT_RELATIME)
  29                 flags |= ST_RELATIME;
  30         return flags;
  31 }
  32
  33 static int flags_by_sb(int s_flags)
  34 {
  35         int flags = 0;
  36         if (s_flags & MS_SYNCHRONOUS)
  37                 flags |= ST_SYNCHRONOUS;
  38         if (s_flags & MS_MANDLOCK)
  39                 flags |= ST_MANDLOCK;
  40         return flags;
  41 }
  42
  43 static int calculate_f_flags(struct vfsmount *mnt)
  44 {
  45         return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
  46                 flags_by_sb(mnt->mnt_sb->s_flags);
  47 }
  48
  49 static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
  50 {
  51         int retval;
  52
  53         if (!dentry->d_sb->s_op->statfs)
  54                 return -ENOSYS;
  55
  56         memset(buf, 0, sizeof(*buf));
  57         retval = security_sb_statfs(dentry);
  58         if (retval)
  59                 return retval;
  60         retval = dentry->d_sb->s_op->statfs(dentry, buf);
  61         if (retval == 0 && buf->f_frsize == 0)
  62                 buf->f_frsize = buf->f_bsize;
  63         return retval;
  64 }
  65
  66 int vfs_statfs(struct path *path, struct kstatfs *buf)
  67 {
  68         int error;
  69
  70         error = statfs_by_dentry(path->dentry, buf);
  71         if (!error)
  72                 buf->f_flags = calculate_f_flags(path->mnt);
  73         return error;
  74 }
  75 EXPORT_SYMBOL(vfs_statfs);
  76
  77 int user_statfs(const char __user *pathname, struct kstatfs *st)
  78 {
  79         struct path path;
  80         int error = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
  81         if (!error) {
  82                 error = vfs_statfs(&path, st);
  83                 path_put(&path);
  84         }
  85         return error;
  86 }
  87
  88 int fd_statfs(int fd, struct kstatfs *st)
  89 {
  90         int fput_needed;
  91         struct file *file = fget_light(fd, &fput_needed);
  92         int error = -EBADF;
  93         if (file) {
  94                 error = vfs_statfs(&file->f_path, st);
  95                 fput_light(file, fput_needed);
  96         }
  97         return error;
  98 }
  99
 100 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
 101 {
 102         struct statfs buf;
 103
 104         if (sizeof(buf) == sizeof(*st))
 105                 memcpy(&buf, st, sizeof(*st));
 106         else {
 107                 if (sizeof buf.f_blocks == 4) {
 108                         if ((st->f_blocks | st->f_bfree | st->f_bavail |
 109                              st->f_bsize | st->f_frsize) &
 110                             0xffffffff00000000ULL)
 111                                 return -EOVERFLOW;
 112                         /*
 113                          * f_files and f_ffree may be -1; it's okay to stuff
 114                          * that into 32 bits
 115                          */
 116                         if (st->f_files != -1 &&
 117                             (st->f_files & 0xffffffff00000000ULL))
 118                                 return -EOVERFLOW;
 119                         if (st->f_ffree != -1 &&
 120                             (st->f_ffree & 0xffffffff00000000ULL))
 121                                 return -EOVERFLOW;
 122                 }
 123
 124                 buf.f_type = st->f_type;
 125                 buf.f_bsize = st->f_bsize;
 126                 buf.f_blocks = st->f_blocks;
 127                 buf.f_bfree = st->f_bfree;
 128                 buf.f_bavail = st->f_bavail;
 129                 buf.f_files = st->f_files;
 130                 buf.f_ffree = st->f_ffree;
 131                 buf.f_fsid = st->f_fsid;
 132                 buf.f_namelen = st->f_namelen;
 133                 buf.f_frsize = st->f_frsize;
 134                 buf.f_flags = st->f_flags;
 135                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 136         }
 137         if (copy_to_user(p, &buf, sizeof(buf)))
 138                 return -EFAULT;
 139         return 0;
 140 }
 141
 142 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 143 {
 144         struct statfs64 buf;
 145         if (sizeof(buf) == sizeof(*st))
 146                 memcpy(&buf, st, sizeof(*st));
 147         else {
 148                 buf.f_type = st->f_type;
 149                 buf.f_bsize = st->f_bsize;
 150                 buf.f_blocks = st->f_blocks;
 151                 buf.f_bfree = st->f_bfree;
 152                 buf.f_bavail = st->f_bavail;
 153                 buf.f_files = st->f_files;
 154                 buf.f_ffree = st->f_ffree;
 155                 buf.f_fsid = st->f_fsid;
 156                 buf.f_namelen = st->f_namelen;
 157                 buf.f_frsize = st->f_frsize;
 158                 buf.f_flags = st->f_flags;
 159                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 160         }
 161         if (copy_to_user(p, &buf, sizeof(buf)))
 162                 return -EFAULT;
 163         return 0;
 164 }
 165
 166 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 167 {
 168         struct kstatfs st;
 169         int error = user_statfs(pathname, &st);
 170         if (!error)
 171                 error = do_statfs_native(&st, buf);
 172         return error;
 173 }
 174
 175 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 176 {
 177         struct kstatfs st;
 178         int error;
 179         if (sz != sizeof(*buf))
 180                 return -EINVAL;
 181         error = user_statfs(pathname, &st);
 182         if (!error)
 183                 error = do_statfs64(&st, buf);
 184         return error;
 185 }
 186
 187 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 188 {
 189         struct kstatfs st;
 190         int error = fd_statfs(fd, &st);
 191         if (!error)
 192                 error = do_statfs_native(&st, buf);
 193         return error;
 194 }
 195
 196 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 197 {
 198         struct kstatfs st;
 199         int error;
 200
 201         if (sz != sizeof(*buf))
 202                 return -EINVAL;
 203
 204         error = fd_statfs(fd, &st);
 205         if (!error)
 206                 error = do_statfs64(&st, buf);
 207         return error;
 208 }
 209
 210 int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
 211 {
 212         struct super_block *s = user_get_super(dev);
 213         int err;
 214         if (!s)
 215                 return -EINVAL;
 216
 217         err = statfs_by_dentry(s->s_root, sbuf);
 218         drop_super(s);
 219         return err;
 220 }
 221
 222 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 223 {
 224         struct ustat tmp;
 225         struct kstatfs sbuf;
 226         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
 227         if (err)
 228                 return err;
 229
 230         memset(&tmp,0,sizeof(struct ustat));
 231         tmp.f_tfree = sbuf.f_bfree;
 232         tmp.f_tinode = sbuf.f_ffree;
 233
 234         return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 235 }