ovl: properly handle large files in ovl_security_fileattr

dentry_open in ovl_security_fileattr fails for any file
larger than 2GB if open method of the underlying filesystem
calls generic_file_open (e.g. fusefs).

The issue can be reproduce using the following script:
(passthrough_ll is an example app from libfuse).

  $ D=/opt/test/mnt
  $ mkdir -p ${D}/{source,base,top/uppr,top/work,ovlfs}
  $ dd if=/dev/zero of=${D}/source/zero.bin bs=1G count=2
  $ passthrough_ll -o source=${D}/source ${D}/base
  $ mount -t overlay overlay \
      -olowerdir=${D}/base,upperdir=${D}/top/uppr,workdir=${D}/top/work \
      ${D}/ovlfs
  $ chmod 0777 ${D}/mnt/ovlfs/zero.bin

Running this script results in "Value too large for defined data type"
error message from chmod.

Signed-off-by: Oleksandr Tymoshenko <ovt@google.com>
Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 35fd3e3..baa54c7 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -616,8 +616,13 @@ static int ovl_security_fileattr(const struct path *realpath, struct fileattr *f
        struct file *file;
        unsigned int cmd;
        int err;
+       unsigned int flags;
+
+       flags = O_RDONLY;
+       if (force_o_largefile())
+               flags |= O_LARGEFILE;
 
-       file = dentry_open(realpath, O_RDONLY, current_cred());
+       file = dentry_open(realpath, flags, current_cred());
        if (IS_ERR(file))
                return PTR_ERR(file);