netlink.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Netlink event notifications for SELinux.
  4 *
  5 * Author: James Morris <jmorris@redhat.com>
  6 *
  7 * Copyright (C) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
  8 */
  9#include <linux/init.h>
 10#include <linux/types.h>
 11#include <linux/slab.h>
 12#include <linux/stddef.h>
 13#include <linux/kernel.h>
 14#include <linux/export.h>
 15#include <linux/skbuff.h>
 16#include <linux/selinux_netlink.h>
 17#include <net/net_namespace.h>
 18#include <net/netlink.h>
 19
 20#include "initcalls.h"
 21#include "security.h"
 22
 23static struct sock *selnl __ro_after_init;
 24
 25static int selnl_msglen(int msgtype)
 26{
 27	int ret = 0;
 28
 29	switch (msgtype) {
 30	case SELNL_MSG_SETENFORCE:
 31		ret = sizeof(struct selnl_msg_setenforce);
 32		break;
 33
 34	case SELNL_MSG_POLICYLOAD:
 35		ret = sizeof(struct selnl_msg_policyload);
 36		break;
 37
 38	default:
 39		BUG();
 40	}
 41	return ret;
 42}
 43
 44static void selnl_add_payload(struct nlmsghdr *nlh, int len, int msgtype, void *data)
 45{
 46	switch (msgtype) {
 47	case SELNL_MSG_SETENFORCE: {
 48		struct selnl_msg_setenforce *msg = nlmsg_data(nlh);
 49
 50		memset(msg, 0, len);
 51		msg->val = *((int *)data);
 52		break;
 53	}
 54
 55	case SELNL_MSG_POLICYLOAD: {
 56		struct selnl_msg_policyload *msg = nlmsg_data(nlh);
 57
 58		memset(msg, 0, len);
 59		msg->seqno = *((u32 *)data);
 60		break;
 61	}
 62
 63	default:
 64		BUG();
 65	}
 66}
 67
 68static void selnl_notify(int msgtype, void *data)
 69{
 70	int len;
 71	sk_buff_data_t tmp;
 72	struct sk_buff *skb;
 73	struct nlmsghdr *nlh;
 74
 75	len = selnl_msglen(msgtype);
 76
 77	skb = nlmsg_new(len, GFP_USER);
 78	if (!skb)
 79		goto oom;
 80
 81	tmp = skb->tail;
 82	nlh = nlmsg_put(skb, 0, 0, msgtype, len, 0);
 83	if (!nlh)
 84		goto out_kfree_skb;
 85	selnl_add_payload(nlh, len, msgtype, data);
 86	nlh->nlmsg_len = skb->tail - tmp;
 87	NETLINK_CB(skb).dst_group = SELNLGRP_AVC;
 88	netlink_broadcast(selnl, skb, 0, SELNLGRP_AVC, GFP_USER);
 89out:
 90	return;
 91
 92out_kfree_skb:
 93	kfree_skb(skb);
 94oom:
 95	pr_err("SELinux:  OOM in %s\n", __func__);
 96	goto out;
 97}
 98
 99void selnl_notify_setenforce(int val)
100{
101	selnl_notify(SELNL_MSG_SETENFORCE, &val);
102}
103
104void selnl_notify_policyload(u32 seqno)
105{
106	selnl_notify(SELNL_MSG_POLICYLOAD, &seqno);
107}
108
109int __init sel_netlink_init(void)
110{
111	struct netlink_kernel_cfg cfg = {
112		.groups	= SELNLGRP_MAX,
113		.flags	= NL_CFG_F_NONROOT_RECV,
114	};
115
116	selnl = netlink_kernel_create(&init_net, NETLINK_SELINUX, &cfg);
117	if (selnl == NULL)
118		panic("SELinux:  Cannot create netlink socket.");
119	return 0;
120}