[PATCH 08/19] cred: Reject inodes with invalid ids in set_create_file_as()

[Serge E. Hallyn]

On Wed, Dec 02, 2015 at 09:40:08AM -0600, Seth Forshee wrote:
> Using INVALID_[UG]ID for the LSM file creation context doesn't
> make sense, so return an error if the inode passed to
> set_create_file_as() has an invalid id.
> 
> Signed-off-by: Seth Forshee <seth.forshee at canonical.com>

Acked-by: Serge Hallyn <serge.hallyn at canonical.com>

> ---
>  kernel/cred.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/cred.c b/kernel/cred.c
> index 71179a09c1d6..ff8606f77d90 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -689,6 +689,8 @@ EXPORT_SYMBOL(set_security_override_from_ctx);
>   */
>  int set_create_files_as(struct cred *new, struct inode *inode)
>  {
> +	if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
> +		return -EINVAL;
>  	new->fsuid = inode->i_uid;
>  	new->fsgid = inode->i_gid;
>  	return security_kernel_create_files_as(new, inode);
> -- 
> 1.9.1
> 
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