1 files changed, 436 insertions, 0 deletions

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
new file mode 100644
index 000000000..513f475c6
--- /dev/null
+++ b/net/ipv4/fib_rules.c
@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		IPv4 Forwarding Information Base: policy rules.
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *		Thomas Graf <tgraf@suug.ch>
+ *
+ * Fixes:
+ *		Rani Assaf	:	local_rule cannot be deleted
+ *		Marc Boucher	:	routing by fwmark
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/netlink.h>
+#include <linux/inetdevice.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+#include <linux/export.h>
+#include <net/inet_dscp.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/tcp.h>
+#include <net/ip_fib.h>
+#include <net/nexthop.h>
+#include <net/fib_rules.h>
+#include <linux/indirect_call_wrapper.h>
+
+struct fib4_rule {
+	struct fib_rule		common;
+	u8			dst_len;
+	u8			src_len;
+	dscp_t			dscp;
+	__be32			src;
+	__be32			srcmask;
+	__be32			dst;
+	__be32			dstmask;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	u32			tclassid;
+#endif
+};
+
+static bool fib4_rule_matchall(const struct fib_rule *rule)
+{
+	struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
+
+	if (r->dst_len || r->src_len || r->dscp)
+		return false;
+	return fib_rule_matchall(rule);
+}
+
+bool fib4_rule_default(const struct fib_rule *rule)
+{
+	if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
+	    rule->l3mdev)
+		return false;
+	if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
+	    rule->table != RT_TABLE_DEFAULT)
+		return false;
+	return true;
+}
+EXPORT_SYMBOL_GPL(fib4_rule_default);
+
+int fib4_rules_dump(struct net *net, struct notifier_block *nb,
+		    struct netlink_ext_ack *extack)
+{
+	return fib_rules_dump(net, nb, AF_INET, extack);
+}
+
+unsigned int fib4_rules_seq_read(struct net *net)
+{
+	return fib_rules_seq_read(net, AF_INET);
+}
+
+int __fib_lookup(struct net *net, struct flowi4 *flp,
+		 struct fib_result *res, unsigned int flags)
+{
+	struct fib_lookup_arg arg = {
+		.result = res,
+		.flags = flags,
+	};
+	int err;
+
+	/* update flow if oif or iif point to device enslaved to l3mdev */
+	l3mdev_update_flow(net, flowi4_to_flowi(flp));
+
+	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (arg.rule)
+		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
+	else
+		res->tclassid = 0;
+#endif
+
+	if (err == -ESRCH)
+		err = -ENETUNREACH;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(__fib_lookup);
+
+INDIRECT_CALLABLE_SCOPE int fib4_rule_action(struct fib_rule *rule,
+					     struct flowi *flp, int flags,
+					     struct fib_lookup_arg *arg)
+{
+	int err = -EAGAIN;
+	struct fib_table *tbl;
+	u32 tb_id;
+
+	switch (rule->action) {
+	case FR_ACT_TO_TBL:
+		break;
+
+	case FR_ACT_UNREACHABLE:
+		return -ENETUNREACH;
+
+	case FR_ACT_PROHIBIT:
+		return -EACCES;
+
+	case FR_ACT_BLACKHOLE:
+	default:
+		return -EINVAL;
+	}
+
+	rcu_read_lock();
+
+	tb_id = fib_rule_get_table(rule, arg);
+	tbl = fib_get_table(rule->fr_net, tb_id);
+	if (tbl)
+		err = fib_table_lookup(tbl, &flp->u.ip4,
+				       (struct fib_result *)arg->result,
+				       arg->flags);
+
+	rcu_read_unlock();
+	return err;
+}
+
+INDIRECT_CALLABLE_SCOPE bool fib4_rule_suppress(struct fib_rule *rule,
+						int flags,
+						struct fib_lookup_arg *arg)
+{
+	struct fib_result *result = arg->result;
+	struct net_device *dev = NULL;
+
+	if (result->fi) {
+		struct fib_nh_common *nhc = fib_info_nhc(result->fi, 0);
+
+		dev = nhc->nhc_dev;
+	}
+
+	/* do not accept result if the route does
+	 * not meet the required prefix length
+	 */
+	if (result->prefixlen <= rule->suppress_prefixlen)
+		goto suppress_route;
+
+	/* do not accept result if the route uses a device
+	 * belonging to a forbidden interface group
+	 */
+	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
+		goto suppress_route;
+
+	return false;
+
+suppress_route:
+	if (!(arg->flags & FIB_LOOKUP_NOREF))
+		fib_info_put(result->fi);
+	return true;
+}
+
+INDIRECT_CALLABLE_SCOPE int fib4_rule_match(struct fib_rule *rule,
+					    struct flowi *fl, int flags)
+{
+	struct fib4_rule *r = (struct fib4_rule *) rule;
+	struct flowi4 *fl4 = &fl->u.ip4;
+	__be32 daddr = fl4->daddr;
+	__be32 saddr = fl4->saddr;
+
+	if (((saddr ^ r->src) & r->srcmask) ||
+	    ((daddr ^ r->dst) & r->dstmask))
+		return 0;
+
+	if (r->dscp && r->dscp != inet_dsfield_to_dscp(fl4->flowi4_tos))
+		return 0;
+
+	if (rule->ip_proto && (rule->ip_proto != fl4->flowi4_proto))
+		return 0;
+
+	if (fib_rule_port_range_set(&rule->sport_range) &&
+	    !fib_rule_port_inrange(&rule->sport_range, fl4->fl4_sport))
+		return 0;
+
+	if (fib_rule_port_range_set(&rule->dport_range) &&
+	    !fib_rule_port_inrange(&rule->dport_range, fl4->fl4_dport))
+		return 0;
+
+	return 1;
+}
+
+static struct fib_table *fib_empty_table(struct net *net)
+{
+	u32 id = 1;
+
+	while (1) {
+		if (!fib_get_table(net, id))
+			return fib_new_table(net, id);
+
+		if (id++ == RT_TABLE_MAX)
+			break;
+	}
+	return NULL;
+}
+
+static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
+			       struct fib_rule_hdr *frh,
+			       struct nlattr **tb,
+			       struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	int err = -EINVAL;
+	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
+
+	if (!inet_validate_dscp(frh->tos)) {
+		NL_SET_ERR_MSG(extack,
+			       "Invalid dsfield (tos): ECN bits must be 0");
+		goto errout;
+	}
+	/* IPv4 currently doesn't handle high order DSCP bits correctly */
+	if (frh->tos & ~IPTOS_TOS_MASK) {
+		NL_SET_ERR_MSG(extack, "Invalid tos");
+		goto errout;
+	}
+	rule4->dscp = inet_dsfield_to_dscp(frh->tos);
+
+	/* split local/main if they are not already split */
+	err = fib_unmerge(net);
+	if (err)
+		goto errout;
+
+	if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {
+		if (rule->action == FR_ACT_TO_TBL) {
+			struct fib_table *table;
+
+			table = fib_empty_table(net);
+			if (!table) {
+				err = -ENOBUFS;
+				goto errout;
+			}
+
+			rule->table = table->tb_id;
+		}
+	}
+
+	if (frh->src_len)
+		rule4->src = nla_get_in_addr(tb[FRA_SRC]);
+
+	if (frh->dst_len)
+		rule4->dst = nla_get_in_addr(tb[FRA_DST]);
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (tb[FRA_FLOW]) {
+		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
+		if (rule4->tclassid)
+			atomic_inc(&net->ipv4.fib_num_tclassid_users);
+	}
+#endif
+
+	if (fib_rule_requires_fldissect(rule))
+		net->ipv4.fib_rules_require_fldissect++;
+
+	rule4->src_len = frh->src_len;
+	rule4->srcmask = inet_make_mask(rule4->src_len);
+	rule4->dst_len = frh->dst_len;
+	rule4->dstmask = inet_make_mask(rule4->dst_len);
+
+	net->ipv4.fib_has_custom_rules = true;
+
+	err = 0;
+errout:
+	return err;
+}
+
+static int fib4_rule_delete(struct fib_rule *rule)
+{
+	struct net *net = rule->fr_net;
+	int err;
+
+	/* split local/main if they are not already split */
+	err = fib_unmerge(net);
+	if (err)
+		goto errout;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (((struct fib4_rule *)rule)->tclassid)
+		atomic_dec(&net->ipv4.fib_num_tclassid_users);
+#endif
+	net->ipv4.fib_has_custom_rules = true;
+
+	if (net->ipv4.fib_rules_require_fldissect &&
+	    fib_rule_requires_fldissect(rule))
+		net->ipv4.fib_rules_require_fldissect--;
+errout:
+	return err;
+}
+
+static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
+			     struct nlattr **tb)
+{
+	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
+
+	if (frh->src_len && (rule4->src_len != frh->src_len))
+		return 0;
+
+	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
+		return 0;
+
+	if (frh->tos && inet_dscp_to_dsfield(rule4->dscp) != frh->tos)
+		return 0;
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
+		return 0;
+#endif
+
+	if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))
+		return 0;
+
+	if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))
+		return 0;
+
+	return 1;
+}
+
+static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
+			  struct fib_rule_hdr *frh)
+{
+	struct fib4_rule *rule4 = (struct fib4_rule *) rule;
+
+	frh->dst_len = rule4->dst_len;
+	frh->src_len = rule4->src_len;
+	frh->tos = inet_dscp_to_dsfield(rule4->dscp);
+
+	if ((rule4->dst_len &&
+	     nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||
+	    (rule4->src_len &&
+	     nla_put_in_addr(skb, FRA_SRC, rule4->src)))
+		goto nla_put_failure;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (rule4->tclassid &&
+	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
+		goto nla_put_failure;
+#endif
+	return 0;
+
+nla_put_failure:
+	return -ENOBUFS;
+}
+
+static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
+{
+	return nla_total_size(4) /* dst */
+	       + nla_total_size(4) /* src */
+	       + nla_total_size(4); /* flow */
+}
+
+static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
+{
+	rt_cache_flush(ops->fro_net);
+}
+
+static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {
+	.family		= AF_INET,
+	.rule_size	= sizeof(struct fib4_rule),
+	.addr_size	= sizeof(u32),
+	.action		= fib4_rule_action,
+	.suppress	= fib4_rule_suppress,
+	.match		= fib4_rule_match,
+	.configure	= fib4_rule_configure,
+	.delete		= fib4_rule_delete,
+	.compare	= fib4_rule_compare,
+	.fill		= fib4_rule_fill,
+	.nlmsg_payload	= fib4_rule_nlmsg_payload,
+	.flush_cache	= fib4_rule_flush_cache,
+	.nlgroup	= RTNLGRP_IPV4_RULE,
+	.owner		= THIS_MODULE,
+};
+
+static int fib_default_rules_init(struct fib_rules_ops *ops)
+{
+	int err;
+
+	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);
+	if (err < 0)
+		return err;
+	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
+	if (err < 0)
+		return err;
+	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
+	if (err < 0)
+		return err;
+	return 0;
+}
+
+int __net_init fib4_rules_init(struct net *net)
+{
+	int err;
+	struct fib_rules_ops *ops;
+
+	ops = fib_rules_register(&fib4_rules_ops_template, net);
+	if (IS_ERR(ops))
+		return PTR_ERR(ops);
+
+	err = fib_default_rules_init(ops);
+	if (err < 0)
+		goto fail;
+	net->ipv4.rules_ops = ops;
+	net->ipv4.fib_has_custom_rules = false;
+	net->ipv4.fib_rules_require_fldissect = 0;
+	return 0;
+
+fail:
+	/* also cleans all rules already added */
+	fib_rules_unregister(ops);
+	return err;
+}
+
+void __net_exit fib4_rules_exit(struct net *net)
+{
+	fib_rules_unregister(net->ipv4.rules_ops);
+}