[PATCH 2/3] selinux: Implement the object_init_security hook

[Stephen Smalley]

On 1/9/19 4:10 AM, Ondrej Mosnacek wrote:
> The hook applies the same logic as selinux_determine_inode_label(), with
> the exception of the super_block handling, which will be enforced on the
> actual inodes by other hooks.
> 
> Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>

Reviewed-by: Stephen Smalley <sds at tycho.nsa.gov>

> ---
>   security/selinux/hooks.c | 41 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 41 insertions(+)
> 
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 7ce012d9ec51..29c038513504 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3526,6 +3526,45 @@ static int selinux_inode_copy_up_xattr(const char *name)
>   	return -EOPNOTSUPP;
>   }
>   
> +/* file-like object operations */
> +
> +/* Used e.g. for kernfs_node for newly created nodes */
> +static int selinux_object_init_security(void *parent_ctx, u32 parent_ctxlen,
> +					const struct qstr *qstr, u16 mode,
> +					void **ctx, u32 *ctxlen)
> +{
> +	const struct task_security_struct *tsec = current_security();
> +	u32 parent_sid, newsid, clen;
> +	int rc;
> +	char *context;
> +
> +	rc = security_context_to_sid(&selinux_state, parent_ctx, parent_ctxlen,
> +				     &parent_sid, GFP_KERNEL);
> +	if (rc)
> +		return rc;
> +
> +	if (tsec->create_sid) {
> +		newsid = tsec->create_sid;
> +	} else {
> +		u16 secclass = inode_mode_to_security_class(mode);
> +
> +		rc = security_transition_sid(&selinux_state, tsec->sid,
> +					     parent_sid, secclass, qstr,
> +					     &newsid);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	rc = security_sid_to_context_force(&selinux_state, newsid,
> +					   &context, &clen);
> +	if (rc)
> +		return rc;
> +
> +	*ctx = context;
> +	*ctxlen = clen;
> +	return 0;
> +}
> +
>   /* file security operations */
>   
>   static int selinux_revalidate_file_permission(struct file *file, int mask)
> @@ -6965,6 +7004,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>   	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(object_init_security, selinux_object_init_security),
> +
>   	LSM_HOOK_INIT(file_permission, selinux_file_permission),
>   	LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
>   	LSM_HOOK_INIT(file_free_security, selinux_file_free_security),
>