Re: [PATCH v5 05/21] ima: move ima_file_free before releasing the file

Mimi Zohar
2011-05-20T00:55:09Z

On Thu, 2011-05-19 at 17:06 -0500, Serge E. Hallyn wrote:
> Quoting Mimi Zohar (zohar@linux.vnet.ibm.com):
> > Integrity appraisal measures files on file_free and stores the file
> > measurement as an xattr. Measure the file before releasing it.
>
> Can you put a bit more in the commit msg about why? What's magic
> about the fs-specific release function?

ima_file_free(), called on __fput(), currently flags files that have
changed, so that the file is re-measured. However, for appraising a
files's integrity, flagging the file is not enough. The file's
security.ima xattr must be updated to reflect any changes. This patch
moves releasing the file to after calculating the new file hash.

> > Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
> > Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
> > ---
> > fs/file_table.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/fs/file_table.c b/fs/file_table.c
> > index 01e4c1e..33f54a1 100644
> > --- a/fs/file_table.c
> > +++ b/fs/file_table.c
> > @@ -243,10 +243,10 @@ static void __fput(struct file *file)
> > if (file->f_op && file->f_op->fasync)
> > file->f_op->fasync(-1, file, 0);
> > }
> > + ima_file_free(file);
> > if (file->f_op && file->f_op->release)
> > file->f_op->release(inode, file);
> > security_file_free(file);
> > - ima_file_free(file);
> > if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
> > !(file->f_mode & FMODE_PATH))) {
> > cdev_put(inode->i_cdev);
> > --