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;
  81         unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
  82 retry:
  83         error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
  84         if (!error) {
  85                 error = vfs_statfs(&path, st);
  86                 path_put(&path);
  87                 if (retry_estale(error, lookup_flags)) {
  88                         lookup_flags |= LOOKUP_REVAL;
  89                         goto retry;
  90                 }
  91         }
  92         return error;
  93 }
  94
  95 int fd_statfs(int fd, struct kstatfs *st)
  96 {
  97         struct fd f = fdget_raw(fd);
  98         int error = -EBADF;
  99         if (f.file) {
 100                 error = vfs_statfs(&f.file->f_path, st);
 101                 fdput(f);
 102         }
 103         return error;
 104 }
 105
 106 static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
 107 {
 108         struct statfs buf;
 109
 110         if (sizeof(buf) == sizeof(*st))
 111                 memcpy(&buf, st, sizeof(*st));
 112         else {
 113                 if (sizeof buf.f_blocks == 4) {
 114                         if ((st->f_blocks | st->f_bfree | st->f_bavail |
 115                              st->f_bsize | st->f_frsize) &
 116                             0xffffffff00000000ULL)
 117                                 return -EOVERFLOW;
 118                         /*
 119                          * f_files and f_ffree may be -1; it's okay to stuff
 120                          * that into 32 bits
 121                          */
 122                         if (st->f_files != -1 &&
 123                             (st->f_files & 0xffffffff00000000ULL))
 124                                 return -EOVERFLOW;
 125                         if (st->f_ffree != -1 &&
 126                             (st->f_ffree & 0xffffffff00000000ULL))
 127                                 return -EOVERFLOW;
 128                 }
 129
 130                 buf.f_type = st->f_type;
 131                 buf.f_bsize = st->f_bsize;
 132                 buf.f_blocks = st->f_blocks;
 133                 buf.f_bfree = st->f_bfree;
 134                 buf.f_bavail = st->f_bavail;
 135                 buf.f_files = st->f_files;
 136                 buf.f_ffree = st->f_ffree;
 137                 buf.f_fsid = st->f_fsid;
 138                 buf.f_namelen = st->f_namelen;
 139                 buf.f_frsize = st->f_frsize;
 140                 buf.f_flags = st->f_flags;
 141                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 142         }
 143         if (copy_to_user(p, &buf, sizeof(buf)))
 144                 return -EFAULT;
 145         return 0;
 146 }
 147
 148 static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 149 {
 150         struct statfs64 buf;
 151         if (sizeof(buf) == sizeof(*st))
 152                 memcpy(&buf, st, sizeof(*st));
 153         else {
 154                 buf.f_type = st->f_type;
 155                 buf.f_bsize = st->f_bsize;
 156                 buf.f_blocks = st->f_blocks;
 157                 buf.f_bfree = st->f_bfree;
 158                 buf.f_bavail = st->f_bavail;
 159                 buf.f_files = st->f_files;
 160                 buf.f_ffree = st->f_ffree;
 161                 buf.f_fsid = st->f_fsid;
 162                 buf.f_namelen = st->f_namelen;
 163                 buf.f_frsize = st->f_frsize;
 164                 buf.f_flags = st->f_flags;
 165                 memset(buf.f_spare, 0, sizeof(buf.f_spare));
 166         }
 167         if (copy_to_user(p, &buf, sizeof(buf)))
 168                 return -EFAULT;
 169         return 0;
 170 }
 171
 172 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 173 {
 174         struct kstatfs st;
 175         int error = user_statfs(pathname, &st);
 176         if (!error)
 177                 error = do_statfs_native(&st, buf);
 178         return error;
 179 }
 180
 181 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 182 {
 183         struct kstatfs st;
 184         int error;
 185         if (sz != sizeof(*buf))
 186                 return -EINVAL;
 187         error = user_statfs(pathname, &st);
 188         if (!error)
 189                 error = do_statfs64(&st, buf);
 190         return error;
 191 }
 192
 193 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 194 {
 195         struct kstatfs st;
 196         int error = fd_statfs(fd, &st);
 197         if (!error)
 198                 error = do_statfs_native(&st, buf);
 199         return error;
 200 }
 201
 202 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 203 {
 204         struct kstatfs st;
 205         int error;
 206
 207         if (sz != sizeof(*buf))
 208                 return -EINVAL;
 209
 210         error = fd_statfs(fd, &st);
 211         if (!error)
 212                 error = do_statfs64(&st, buf);
 213         return error;
 214 }
 215
 216 int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
 217 {
 218         struct super_block *s = user_get_super(dev);
 219         int err;
 220         if (!s)
 221                 return -EINVAL;
 222
 223         err = statfs_by_dentry(s->s_root, sbuf);
 224         drop_super(s);
 225         return err;
 226 }
 227
 228 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 229 {
 230         struct ustat tmp;
 231         struct kstatfs sbuf;
 232         int err = vfs_ustat(new_decode_dev(dev), &sbuf);
 233         if (err)
 234                 return err;
 235
 236         memset(&tmp,0,sizeof(struct ustat));
 237         tmp.f_tfree = sbuf.f_bfree;
 238         tmp.f_tinode = sbuf.f_ffree;
 239
 240         return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 241 }