[v2,4/8] vfs: add missing checks to copy_file_range
diff mbox series

Message ID 20190526061100.21761-5-amir73il@gmail.com
State New
Headers show
Series
  • Fixes for major copy_file_range() issues
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Commit Message

Amir Goldstein May 26, 2019, 6:10 a.m. UTC
Like the clone and dedupe interfaces we've recently fixed, the
copy_file_range() implementation is missing basic sanity, limits and
boundary condition tests on the parameters that are passed to it
from userspace. Create a new "generic_copy_file_checks()" function
modelled on the generic_remap_checks() function to provide this
missing functionality.

[Amir] Shorten copy length instead of checking pos_in limits
because input file size already abides by the limits.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/read_write.c    |  3 ++-
 include/linux/fs.h |  3 +++
 mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

Comments

Darrick J. Wong May 28, 2019, 4:18 p.m. UTC | #1
On Sun, May 26, 2019 at 09:10:55AM +0300, Amir Goldstein wrote:
> Like the clone and dedupe interfaces we've recently fixed, the
> copy_file_range() implementation is missing basic sanity, limits and
> boundary condition tests on the parameters that are passed to it
> from userspace. Create a new "generic_copy_file_checks()" function
> modelled on the generic_remap_checks() function to provide this
> missing functionality.
> 
> [Amir] Shorten copy length instead of checking pos_in limits
> because input file size already abides by the limits.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>  fs/read_write.c    |  3 ++-
>  include/linux/fs.h |  3 +++
>  mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/read_write.c b/fs/read_write.c
> index f1900bdb3127..b0fb1176b628 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>  	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
>  		return -EXDEV;
>  
> -	ret = generic_file_rw_checks(file_in, file_out);
> +	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
> +				       flags);
>  	if (unlikely(ret))
>  		return ret;
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 89b9b73eb581..e4d382c4342a 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
>  				struct file *file_out, loff_t pos_out,
>  				loff_t *count, unsigned int remap_flags);
>  extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
> +extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> +				    struct file *file_out, loff_t pos_out,
> +				    size_t *count, unsigned int flags);
>  extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
>  extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
>  extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 798aac92cd76..1852fbf08eeb 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3064,6 +3064,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
>  	return 0;
>  }
>  
> +/*
> + * Performs necessary checks before doing a file copy
> + *
> + * Can adjust amount of bytes to copy

That's the @req_count parameter, correct?

> + * Returns appropriate error code that caller should return or
> + * zero in case the copy should be allowed.
> + */
> +int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> +			     struct file *file_out, loff_t pos_out,
> +			     size_t *req_count, unsigned int flags)
> +{
> +	struct inode *inode_in = file_inode(file_in);
> +	struct inode *inode_out = file_inode(file_out);
> +	uint64_t count = *req_count;
> +	loff_t size_in;
> +	int ret;
> +
> +	ret = generic_file_rw_checks(file_in, file_out);
> +	if (ret)
> +		return ret;
> +
> +	/* Don't touch certain kinds of inodes */
> +	if (IS_IMMUTABLE(inode_out))
> +		return -EPERM;
> +
> +	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
> +		return -ETXTBSY;
> +
> +	/* Ensure offsets don't wrap. */
> +	if (pos_in + count < pos_in || pos_out + count < pos_out)
> +		return -EOVERFLOW;
> +
> +	/* Shorten the copy to EOF */
> +	size_in = i_size_read(inode_in);
> +	if (pos_in >= size_in)
> +		count = 0;
> +	else
> +		count = min(count, size_in - (uint64_t)pos_in);

Do we need a call to generic_access_check_limits(file_in...) here to
prevent copies from ranges that the page cache doesn't support?

--D

> +	ret = generic_write_check_limits(file_out, pos_out, &count);
> +	if (ret)
> +		return ret;
> +
> +	/* Don't allow overlapped copying within the same file. */
> +	if (inode_in == inode_out &&
> +	    pos_out + count > pos_in &&
> +	    pos_out < pos_in + count)
> +		return -EINVAL;
> +
> +	*req_count = count;
> +	return 0;
> +}
> +
>  int pagecache_write_begin(struct file *file, struct address_space *mapping,
>  				loff_t pos, unsigned len, unsigned flags,
>  				struct page **pagep, void **fsdata)
> -- 
> 2.17.1
>
Amir Goldstein May 28, 2019, 4:26 p.m. UTC | #2
On Tue, May 28, 2019 at 7:18 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> On Sun, May 26, 2019 at 09:10:55AM +0300, Amir Goldstein wrote:
> > Like the clone and dedupe interfaces we've recently fixed, the
> > copy_file_range() implementation is missing basic sanity, limits and
> > boundary condition tests on the parameters that are passed to it
> > from userspace. Create a new "generic_copy_file_checks()" function
> > modelled on the generic_remap_checks() function to provide this
> > missing functionality.
> >
> > [Amir] Shorten copy length instead of checking pos_in limits
> > because input file size already abides by the limits.
> >
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >  fs/read_write.c    |  3 ++-
> >  include/linux/fs.h |  3 +++
> >  mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 58 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index f1900bdb3127..b0fb1176b628 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> >       if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> >               return -EXDEV;
> >
> > -     ret = generic_file_rw_checks(file_in, file_out);
> > +     ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
> > +                                    flags);
> >       if (unlikely(ret))
> >               return ret;
> >
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 89b9b73eb581..e4d382c4342a 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
> >                               struct file *file_out, loff_t pos_out,
> >                               loff_t *count, unsigned int remap_flags);
> >  extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
> > +extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > +                                 struct file *file_out, loff_t pos_out,
> > +                                 size_t *count, unsigned int flags);
> >  extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
> >  extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
> >  extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 798aac92cd76..1852fbf08eeb 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -3064,6 +3064,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
> >       return 0;
> >  }
> >
> > +/*
> > + * Performs necessary checks before doing a file copy
> > + *
> > + * Can adjust amount of bytes to copy
>
> That's the @req_count parameter, correct?

Correct. Same as generic_remap_checks()

>
> > + * Returns appropriate error code that caller should return or
> > + * zero in case the copy should be allowed.
> > + */
> > +int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > +                          struct file *file_out, loff_t pos_out,
> > +                          size_t *req_count, unsigned int flags)
> > +{
> > +     struct inode *inode_in = file_inode(file_in);
> > +     struct inode *inode_out = file_inode(file_out);
> > +     uint64_t count = *req_count;
> > +     loff_t size_in;
> > +     int ret;
> > +
> > +     ret = generic_file_rw_checks(file_in, file_out);
> > +     if (ret)
> > +             return ret;
> > +
> > +     /* Don't touch certain kinds of inodes */
> > +     if (IS_IMMUTABLE(inode_out))
> > +             return -EPERM;
> > +
> > +     if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
> > +             return -ETXTBSY;
> > +
> > +     /* Ensure offsets don't wrap. */
> > +     if (pos_in + count < pos_in || pos_out + count < pos_out)
> > +             return -EOVERFLOW;
> > +
> > +     /* Shorten the copy to EOF */
> > +     size_in = i_size_read(inode_in);
> > +     if (pos_in >= size_in)
> > +             count = 0;
> > +     else
> > +             count = min(count, size_in - (uint64_t)pos_in);
>
> Do we need a call to generic_access_check_limits(file_in...) here to
> prevent copies from ranges that the page cache doesn't support?

No. Because i_size cannot be of an illegal size and we cap
the read to i_size.
I also removed generic_access_check_limits() from generic_remap_checks()
for a similar reason in patch #8.

Thanks,
Amir.
Darrick J. Wong May 28, 2019, 4:31 p.m. UTC | #3
On Tue, May 28, 2019 at 07:26:29PM +0300, Amir Goldstein wrote:
> On Tue, May 28, 2019 at 7:18 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
> >
> > On Sun, May 26, 2019 at 09:10:55AM +0300, Amir Goldstein wrote:
> > > Like the clone and dedupe interfaces we've recently fixed, the
> > > copy_file_range() implementation is missing basic sanity, limits and
> > > boundary condition tests on the parameters that are passed to it
> > > from userspace. Create a new "generic_copy_file_checks()" function
> > > modelled on the generic_remap_checks() function to provide this
> > > missing functionality.
> > >
> > > [Amir] Shorten copy length instead of checking pos_in limits
> > > because input file size already abides by the limits.
> > >
> > > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > > ---
> > >  fs/read_write.c    |  3 ++-
> > >  include/linux/fs.h |  3 +++
> > >  mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 58 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/read_write.c b/fs/read_write.c
> > > index f1900bdb3127..b0fb1176b628 100644
> > > --- a/fs/read_write.c
> > > +++ b/fs/read_write.c
> > > @@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> > >       if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> > >               return -EXDEV;
> > >
> > > -     ret = generic_file_rw_checks(file_in, file_out);
> > > +     ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
> > > +                                    flags);
> > >       if (unlikely(ret))
> > >               return ret;
> > >
> > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > index 89b9b73eb581..e4d382c4342a 100644
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
> > >                               struct file *file_out, loff_t pos_out,
> > >                               loff_t *count, unsigned int remap_flags);
> > >  extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
> > > +extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > > +                                 struct file *file_out, loff_t pos_out,
> > > +                                 size_t *count, unsigned int flags);
> > >  extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
> > >  extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
> > >  extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
> > > diff --git a/mm/filemap.c b/mm/filemap.c
> > > index 798aac92cd76..1852fbf08eeb 100644
> > > --- a/mm/filemap.c
> > > +++ b/mm/filemap.c
> > > @@ -3064,6 +3064,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
> > >       return 0;
> > >  }
> > >
> > > +/*
> > > + * Performs necessary checks before doing a file copy
> > > + *
> > > + * Can adjust amount of bytes to copy
> >
> > That's the @req_count parameter, correct?
> 
> Correct. Same as generic_remap_checks()

Ok.  Would you mind updating the comment?

> >
> > > + * Returns appropriate error code that caller should return or
> > > + * zero in case the copy should be allowed.
> > > + */
> > > +int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > > +                          struct file *file_out, loff_t pos_out,
> > > +                          size_t *req_count, unsigned int flags)
> > > +{
> > > +     struct inode *inode_in = file_inode(file_in);
> > > +     struct inode *inode_out = file_inode(file_out);
> > > +     uint64_t count = *req_count;
> > > +     loff_t size_in;
> > > +     int ret;
> > > +
> > > +     ret = generic_file_rw_checks(file_in, file_out);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     /* Don't touch certain kinds of inodes */
> > > +     if (IS_IMMUTABLE(inode_out))
> > > +             return -EPERM;
> > > +
> > > +     if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
> > > +             return -ETXTBSY;
> > > +
> > > +     /* Ensure offsets don't wrap. */
> > > +     if (pos_in + count < pos_in || pos_out + count < pos_out)
> > > +             return -EOVERFLOW;
> > > +
> > > +     /* Shorten the copy to EOF */
> > > +     size_in = i_size_read(inode_in);
> > > +     if (pos_in >= size_in)
> > > +             count = 0;
> > > +     else
> > > +             count = min(count, size_in - (uint64_t)pos_in);
> >
> > Do we need a call to generic_access_check_limits(file_in...) here to
> > prevent copies from ranges that the page cache doesn't support?
> 
> No. Because i_size cannot be of an illegal size and we cap
> the read to i_size.
> I also removed generic_access_check_limits() from generic_remap_checks()
> for a similar reason in patch #8.

<nod>

--D

> Thanks,
> Amir.
Amir Goldstein May 28, 2019, 4:39 p.m. UTC | #4
On Tue, May 28, 2019 at 7:31 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> On Tue, May 28, 2019 at 07:26:29PM +0300, Amir Goldstein wrote:
> > On Tue, May 28, 2019 at 7:18 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
> > >
> > > On Sun, May 26, 2019 at 09:10:55AM +0300, Amir Goldstein wrote:
> > > > Like the clone and dedupe interfaces we've recently fixed, the
> > > > copy_file_range() implementation is missing basic sanity, limits and
> > > > boundary condition tests on the parameters that are passed to it
> > > > from userspace. Create a new "generic_copy_file_checks()" function
> > > > modelled on the generic_remap_checks() function to provide this
> > > > missing functionality.
> > > >
> > > > [Amir] Shorten copy length instead of checking pos_in limits
> > > > because input file size already abides by the limits.
> > > >
> > > > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > > > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > > > ---
> > > >  fs/read_write.c    |  3 ++-
> > > >  include/linux/fs.h |  3 +++
> > > >  mm/filemap.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++++
> > > >  3 files changed, 58 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/fs/read_write.c b/fs/read_write.c
> > > > index f1900bdb3127..b0fb1176b628 100644
> > > > --- a/fs/read_write.c
> > > > +++ b/fs/read_write.c
> > > > @@ -1626,7 +1626,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> > > >       if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> > > >               return -EXDEV;
> > > >
> > > > -     ret = generic_file_rw_checks(file_in, file_out);
> > > > +     ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
> > > > +                                    flags);
> > > >       if (unlikely(ret))
> > > >               return ret;
> > > >
> > > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > > index 89b9b73eb581..e4d382c4342a 100644
> > > > --- a/include/linux/fs.h
> > > > +++ b/include/linux/fs.h
> > > > @@ -3050,6 +3050,9 @@ extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
> > > >                               struct file *file_out, loff_t pos_out,
> > > >                               loff_t *count, unsigned int remap_flags);
> > > >  extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
> > > > +extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > > > +                                 struct file *file_out, loff_t pos_out,
> > > > +                                 size_t *count, unsigned int flags);
> > > >  extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
> > > >  extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
> > > >  extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
> > > > diff --git a/mm/filemap.c b/mm/filemap.c
> > > > index 798aac92cd76..1852fbf08eeb 100644
> > > > --- a/mm/filemap.c
> > > > +++ b/mm/filemap.c
> > > > @@ -3064,6 +3064,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
> > > >       return 0;
> > > >  }
> > > >
> > > > +/*
> > > > + * Performs necessary checks before doing a file copy
> > > > + *
> > > > + * Can adjust amount of bytes to copy
> > >
> > > That's the @req_count parameter, correct?
> >
> > Correct. Same as generic_remap_checks()
>
> Ok.  Would you mind updating the comment?
>
OK.

Thanks,
Amir.

Patch
diff mbox series

diff --git a/fs/read_write.c b/fs/read_write.c
index f1900bdb3127..b0fb1176b628 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1626,7 +1626,8 @@  ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
 		return -EXDEV;
 
-	ret = generic_file_rw_checks(file_in, file_out);
+	ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
+				       flags);
 	if (unlikely(ret))
 		return ret;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 89b9b73eb581..e4d382c4342a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3050,6 +3050,9 @@  extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
 				struct file *file_out, loff_t pos_out,
 				loff_t *count, unsigned int remap_flags);
 extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
+extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
+				    struct file *file_out, loff_t pos_out,
+				    size_t *count, unsigned int flags);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index 798aac92cd76..1852fbf08eeb 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3064,6 +3064,59 @@  int generic_file_rw_checks(struct file *file_in, struct file *file_out)
 	return 0;
 }
 
+/*
+ * Performs necessary checks before doing a file copy
+ *
+ * Can adjust amount of bytes to copy
+ * Returns appropriate error code that caller should return or
+ * zero in case the copy should be allowed.
+ */
+int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
+			     struct file *file_out, loff_t pos_out,
+			     size_t *req_count, unsigned int flags)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+	uint64_t count = *req_count;
+	loff_t size_in;
+	int ret;
+
+	ret = generic_file_rw_checks(file_in, file_out);
+	if (ret)
+		return ret;
+
+	/* Don't touch certain kinds of inodes */
+	if (IS_IMMUTABLE(inode_out))
+		return -EPERM;
+
+	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
+		return -ETXTBSY;
+
+	/* Ensure offsets don't wrap. */
+	if (pos_in + count < pos_in || pos_out + count < pos_out)
+		return -EOVERFLOW;
+
+	/* Shorten the copy to EOF */
+	size_in = i_size_read(inode_in);
+	if (pos_in >= size_in)
+		count = 0;
+	else
+		count = min(count, size_in - (uint64_t)pos_in);
+
+	ret = generic_write_check_limits(file_out, pos_out, &count);
+	if (ret)
+		return ret;
+
+	/* Don't allow overlapped copying within the same file. */
+	if (inode_in == inode_out &&
+	    pos_out + count > pos_in &&
+	    pos_out < pos_in + count)
+		return -EINVAL;
+
+	*req_count = count;
+	return 0;
+}
+
 int pagecache_write_begin(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
 				struct page **pagep, void **fsdata)