On 07/13/2016 10:44 AM, Vivek Goyal wrote:
> When a file is copied up in overlay, we have already created file on upper/
> with right label and there is no need to copy up selinux label/xattr from
> lower file to upper file. In fact in case of context mount, we don't want
> to copy up label as newly created file got its label from context= option.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
> security/selinux/hooks.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index c82ee54..4fda548 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3290,6 +3290,21 @@ static int selinux_inode_copy_up(struct dentry *src, struct cred **new)
> return 0;
> }
>
> +static int selinux_inode_copy_up_xattr(const char *name)
> +{
> + /* The copy_up hook above sets the initial context on an inode, but we
> + * don't then want to overwrite it by blindly copying all the lower
> + * xattrs up. Instead, we have to filter out SELinux-related xattrs.
> + */
> + if (strcmp(name, XATTR_NAME_SELINUX) == 0)
> + return 1; /* Discard */
> + /*
> + * Any other attribute apart from SELINUX is not claimed, supported
> + * by selinux.
> + */
> + return -EOPNOTSUPP;
> +}
> +
> /* file security operations */
>
> static int selinux_revalidate_file_permission(struct file *file, int mask)
> @@ -6077,6 +6092,7 @@ static struct security_hook_list selinux_hooks[] = {
> LSM_HOOK_INIT(inode_listsecurity, selinux_inode_listsecurity),
> LSM_HOOK_INIT(inode_getsecid, selinux_inode_getsecid),
> LSM_HOOK_INIT(inode_copy_up, selinux_inode_copy_up),
> + LSM_HOOK_INIT(inode_copy_up_xattr, selinux_inode_copy_up_xattr),
>
> LSM_HOOK_INIT(file_permission, selinux_file_permission),
> LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
>
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