linux/fs/statfs.c
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   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
  12static 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
  33static 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
  43static 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
  49static 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
  66int 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}
  75EXPORT_SYMBOL(vfs_statfs);
  76
  77int 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
  88int fd_statfs(int fd, struct kstatfs *st)
  89{
  90        struct fd f = fdget(fd);
  91        int error = -EBADF;
  92        if (f.file) {
  93                error = vfs_statfs(&f.file->f_path, st);
  94                fdput(f);
  95        }
  96        return error;
  97}
  98
  99static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
 100{
 101        struct statfs buf;
 102
 103        if (sizeof(buf) == sizeof(*st))
 104                memcpy(&buf, st, sizeof(*st));
 105        else {
 106                if (sizeof buf.f_blocks == 4) {
 107                        if ((st->f_blocks | st->f_bfree | st->f_bavail |
 108                             st->f_bsize | st->f_frsize) &
 109                            0xffffffff00000000ULL)
 110                                return -EOVERFLOW;
 111                        /*
 112                         * f_files and f_ffree may be -1; it's okay to stuff
 113                         * that into 32 bits
 114                         */
 115                        if (st->f_files != -1 &&
 116                            (st->f_files & 0xffffffff00000000ULL))
 117                                return -EOVERFLOW;
 118                        if (st->f_ffree != -1 &&
 119                            (st->f_ffree & 0xffffffff00000000ULL))
 120                                return -EOVERFLOW;
 121                }
 122
 123                buf.f_type = st->f_type;
 124                buf.f_bsize = st->f_bsize;
 125                buf.f_blocks = st->f_blocks;
 126                buf.f_bfree = st->f_bfree;
 127                buf.f_bavail = st->f_bavail;
 128                buf.f_files = st->f_files;
 129                buf.f_ffree = st->f_ffree;
 130                buf.f_fsid = st->f_fsid;
 131                buf.f_namelen = st->f_namelen;
 132                buf.f_frsize = st->f_frsize;
 133                buf.f_flags = st->f_flags;
 134                memset(buf.f_spare, 0, sizeof(buf.f_spare));
 135        }
 136        if (copy_to_user(p, &buf, sizeof(buf)))
 137                return -EFAULT;
 138        return 0;
 139}
 140
 141static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 142{
 143        struct statfs64 buf;
 144        if (sizeof(buf) == sizeof(*st))
 145                memcpy(&buf, st, sizeof(*st));
 146        else {
 147                buf.f_type = st->f_type;
 148                buf.f_bsize = st->f_bsize;
 149                buf.f_blocks = st->f_blocks;
 150                buf.f_bfree = st->f_bfree;
 151                buf.f_bavail = st->f_bavail;
 152                buf.f_files = st->f_files;
 153                buf.f_ffree = st->f_ffree;
 154                buf.f_fsid = st->f_fsid;
 155                buf.f_namelen = st->f_namelen;
 156                buf.f_frsize = st->f_frsize;
 157                buf.f_flags = st->f_flags;
 158                memset(buf.f_spare, 0, sizeof(buf.f_spare));
 159        }
 160        if (copy_to_user(p, &buf, sizeof(buf)))
 161                return -EFAULT;
 162        return 0;
 163}
 164
 165SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 166{
 167        struct kstatfs st;
 168        int error = user_statfs(pathname, &st);
 169        if (!error)
 170                error = do_statfs_native(&st, buf);
 171        return error;
 172}
 173
 174SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 175{
 176        struct kstatfs st;
 177        int error;
 178        if (sz != sizeof(*buf))
 179                return -EINVAL;
 180        error = user_statfs(pathname, &st);
 181        if (!error)
 182                error = do_statfs64(&st, buf);
 183        return error;
 184}
 185
 186SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 187{
 188        struct kstatfs st;
 189        int error = fd_statfs(fd, &st);
 190        if (!error)
 191                error = do_statfs_native(&st, buf);
 192        return error;
 193}
 194
 195SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 196{
 197        struct kstatfs st;
 198        int error;
 199
 200        if (sz != sizeof(*buf))
 201                return -EINVAL;
 202
 203        error = fd_statfs(fd, &st);
 204        if (!error)
 205                error = do_statfs64(&st, buf);
 206        return error;
 207}
 208
 209int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
 210{
 211        struct super_block *s = user_get_super(dev);
 212        int err;
 213        if (!s)
 214                return -EINVAL;
 215
 216        err = statfs_by_dentry(s->s_root, sbuf);
 217        drop_super(s);
 218        return err;
 219}
 220
 221SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 222{
 223        struct ustat tmp;
 224        struct kstatfs sbuf;
 225        int err = vfs_ustat(new_decode_dev(dev), &sbuf);
 226        if (err)
 227                return err;
 228
 229        memset(&tmp,0,sizeof(struct ustat));
 230        tmp.f_tfree = sbuf.f_bfree;
 231        tmp.f_tinode = sbuf.f_ffree;
 232
 233        return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 234}
 235
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