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cc3a7bfe62
Today, put_compat_statfs64() disallows nearly any field value over
2^32 if f_bsize is only 32 bits, but that makes no sense.
compat_statfs64 is there for the explicit purpose of providing 64-bit
fields for f_files, f_ffree, etc. And f_bsize is always only 32 bits.
As a result, 32-bit userspace gets -EOVERFLOW for i.e. large file
counts even with -D_FILE_OFFSET_BITS=64 set.
In reality, only f_bsize and f_frsize can legitimately overflow
(fields like f_type and f_namelen should never be large), so test
only those fields.
This bug was discussed at length some time ago, and this is the proposal
Al suggested at https://lkml.org/lkml/2018/8/6/640. It seemed to get
dropped amid the discussion of other related changes, but this
part seems obviously correct on its own, so I've picked it up and
sent it, for expediency.
Fixes: 64d2ab32ef ("vfs: fix put_compat_statfs64() does not handle errors")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
402 lines
9.6 KiB
C
402 lines
9.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/syscalls.h>
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/statfs.h>
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#include <linux/security.h>
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#include <linux/uaccess.h>
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#include <linux/compat.h>
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#include "internal.h"
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static int flags_by_mnt(int mnt_flags)
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{
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int flags = 0;
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if (mnt_flags & MNT_READONLY)
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flags |= ST_RDONLY;
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if (mnt_flags & MNT_NOSUID)
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flags |= ST_NOSUID;
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if (mnt_flags & MNT_NODEV)
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flags |= ST_NODEV;
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if (mnt_flags & MNT_NOEXEC)
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flags |= ST_NOEXEC;
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if (mnt_flags & MNT_NOATIME)
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flags |= ST_NOATIME;
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if (mnt_flags & MNT_NODIRATIME)
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flags |= ST_NODIRATIME;
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if (mnt_flags & MNT_RELATIME)
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flags |= ST_RELATIME;
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return flags;
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}
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static int flags_by_sb(int s_flags)
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{
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int flags = 0;
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if (s_flags & SB_SYNCHRONOUS)
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flags |= ST_SYNCHRONOUS;
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if (s_flags & SB_MANDLOCK)
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flags |= ST_MANDLOCK;
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if (s_flags & SB_RDONLY)
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flags |= ST_RDONLY;
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return flags;
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}
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static int calculate_f_flags(struct vfsmount *mnt)
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{
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return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
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flags_by_sb(mnt->mnt_sb->s_flags);
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}
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static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
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{
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int retval;
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if (!dentry->d_sb->s_op->statfs)
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return -ENOSYS;
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memset(buf, 0, sizeof(*buf));
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retval = security_sb_statfs(dentry);
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if (retval)
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return retval;
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retval = dentry->d_sb->s_op->statfs(dentry, buf);
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if (retval == 0 && buf->f_frsize == 0)
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buf->f_frsize = buf->f_bsize;
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return retval;
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}
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int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
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{
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struct kstatfs st;
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int error;
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error = statfs_by_dentry(dentry, &st);
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if (error)
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return error;
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*fsid = st.f_fsid;
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return 0;
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}
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EXPORT_SYMBOL(vfs_get_fsid);
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int vfs_statfs(const struct path *path, struct kstatfs *buf)
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{
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int error;
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error = statfs_by_dentry(path->dentry, buf);
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if (!error)
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buf->f_flags = calculate_f_flags(path->mnt);
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return error;
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}
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EXPORT_SYMBOL(vfs_statfs);
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int user_statfs(const char __user *pathname, struct kstatfs *st)
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{
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struct path path;
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int error;
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unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
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retry:
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error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
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if (!error) {
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error = vfs_statfs(&path, st);
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path_put(&path);
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if (retry_estale(error, lookup_flags)) {
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lookup_flags |= LOOKUP_REVAL;
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goto retry;
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}
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}
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return error;
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}
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int fd_statfs(int fd, struct kstatfs *st)
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{
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struct fd f = fdget_raw(fd);
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int error = -EBADF;
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if (f.file) {
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error = vfs_statfs(&f.file->f_path, st);
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fdput(f);
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}
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return error;
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}
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static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
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{
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struct statfs buf;
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if (sizeof(buf) == sizeof(*st))
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memcpy(&buf, st, sizeof(*st));
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else {
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if (sizeof buf.f_blocks == 4) {
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if ((st->f_blocks | st->f_bfree | st->f_bavail |
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st->f_bsize | st->f_frsize) &
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0xffffffff00000000ULL)
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return -EOVERFLOW;
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/*
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* f_files and f_ffree may be -1; it's okay to stuff
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* that into 32 bits
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*/
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if (st->f_files != -1 &&
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(st->f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (st->f_ffree != -1 &&
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(st->f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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buf.f_type = st->f_type;
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buf.f_bsize = st->f_bsize;
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buf.f_blocks = st->f_blocks;
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buf.f_bfree = st->f_bfree;
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buf.f_bavail = st->f_bavail;
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buf.f_files = st->f_files;
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buf.f_ffree = st->f_ffree;
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buf.f_fsid = st->f_fsid;
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buf.f_namelen = st->f_namelen;
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buf.f_frsize = st->f_frsize;
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buf.f_flags = st->f_flags;
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memset(buf.f_spare, 0, sizeof(buf.f_spare));
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}
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if (copy_to_user(p, &buf, sizeof(buf)))
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return -EFAULT;
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return 0;
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}
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static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
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{
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struct statfs64 buf;
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if (sizeof(buf) == sizeof(*st))
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memcpy(&buf, st, sizeof(*st));
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else {
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buf.f_type = st->f_type;
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buf.f_bsize = st->f_bsize;
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buf.f_blocks = st->f_blocks;
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buf.f_bfree = st->f_bfree;
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buf.f_bavail = st->f_bavail;
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buf.f_files = st->f_files;
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buf.f_ffree = st->f_ffree;
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buf.f_fsid = st->f_fsid;
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buf.f_namelen = st->f_namelen;
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buf.f_frsize = st->f_frsize;
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buf.f_flags = st->f_flags;
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memset(buf.f_spare, 0, sizeof(buf.f_spare));
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}
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if (copy_to_user(p, &buf, sizeof(buf)))
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return -EFAULT;
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return 0;
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}
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SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
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{
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struct kstatfs st;
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int error = user_statfs(pathname, &st);
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if (!error)
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error = do_statfs_native(&st, buf);
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return error;
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}
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SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
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{
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struct kstatfs st;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = user_statfs(pathname, &st);
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if (!error)
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error = do_statfs64(&st, buf);
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return error;
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}
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SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
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{
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struct kstatfs st;
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int error = fd_statfs(fd, &st);
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if (!error)
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error = do_statfs_native(&st, buf);
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return error;
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}
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SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
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{
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struct kstatfs st;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = fd_statfs(fd, &st);
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if (!error)
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error = do_statfs64(&st, buf);
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return error;
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}
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static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
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{
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struct super_block *s = user_get_super(dev);
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int err;
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if (!s)
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return -EINVAL;
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err = statfs_by_dentry(s->s_root, sbuf);
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drop_super(s);
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return err;
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}
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SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
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{
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struct ustat tmp;
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struct kstatfs sbuf;
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int err = vfs_ustat(new_decode_dev(dev), &sbuf);
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if (err)
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return err;
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memset(&tmp,0,sizeof(struct ustat));
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tmp.f_tfree = sbuf.f_bfree;
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tmp.f_tinode = sbuf.f_ffree;
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return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
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}
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#ifdef CONFIG_COMPAT
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static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
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{
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struct compat_statfs buf;
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if (sizeof ubuf->f_blocks == 4) {
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if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
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kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
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return -EOVERFLOW;
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/* f_files and f_ffree may be -1; it's okay
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* to stuff that into 32 bits */
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if (kbuf->f_files != 0xffffffffffffffffULL
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&& (kbuf->f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (kbuf->f_ffree != 0xffffffffffffffffULL
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&& (kbuf->f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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memset(&buf, 0, sizeof(struct compat_statfs));
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buf.f_type = kbuf->f_type;
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buf.f_bsize = kbuf->f_bsize;
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buf.f_blocks = kbuf->f_blocks;
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buf.f_bfree = kbuf->f_bfree;
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buf.f_bavail = kbuf->f_bavail;
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buf.f_files = kbuf->f_files;
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buf.f_ffree = kbuf->f_ffree;
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buf.f_namelen = kbuf->f_namelen;
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buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
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buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
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buf.f_frsize = kbuf->f_frsize;
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buf.f_flags = kbuf->f_flags;
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if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
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return -EFAULT;
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return 0;
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}
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/*
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* The following statfs calls are copies of code from fs/statfs.c and
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* should be checked against those from time to time
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*/
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COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
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{
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struct kstatfs tmp;
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int error = user_statfs(pathname, &tmp);
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if (!error)
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error = put_compat_statfs(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
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{
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struct kstatfs tmp;
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int error = fd_statfs(fd, &tmp);
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if (!error)
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error = put_compat_statfs(buf, &tmp);
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return error;
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}
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static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
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{
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struct compat_statfs64 buf;
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if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
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return -EOVERFLOW;
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memset(&buf, 0, sizeof(struct compat_statfs64));
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buf.f_type = kbuf->f_type;
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buf.f_bsize = kbuf->f_bsize;
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buf.f_blocks = kbuf->f_blocks;
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buf.f_bfree = kbuf->f_bfree;
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buf.f_bavail = kbuf->f_bavail;
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buf.f_files = kbuf->f_files;
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buf.f_ffree = kbuf->f_ffree;
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buf.f_namelen = kbuf->f_namelen;
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buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
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buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
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buf.f_frsize = kbuf->f_frsize;
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buf.f_flags = kbuf->f_flags;
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if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
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return -EFAULT;
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return 0;
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}
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int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
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{
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struct kstatfs tmp;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = user_statfs(pathname, &tmp);
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if (!error)
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error = put_compat_statfs64(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
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{
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return kcompat_sys_statfs64(pathname, sz, buf);
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}
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int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
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{
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struct kstatfs tmp;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = fd_statfs(fd, &tmp);
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if (!error)
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error = put_compat_statfs64(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
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{
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return kcompat_sys_fstatfs64(fd, sz, buf);
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}
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/*
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* This is a copy of sys_ustat, just dealing with a structure layout.
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* Given how simple this syscall is that apporach is more maintainable
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* than the various conversion hacks.
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*/
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COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
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{
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struct compat_ustat tmp;
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struct kstatfs sbuf;
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int err = vfs_ustat(new_decode_dev(dev), &sbuf);
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if (err)
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return err;
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memset(&tmp, 0, sizeof(struct compat_ustat));
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tmp.f_tfree = sbuf.f_bfree;
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tmp.f_tinode = sbuf.f_ffree;
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if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
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return -EFAULT;
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return 0;
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}
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#endif
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