selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 432 insertions, 0 deletions

diff --git a/include/net/route.h b/include/net/route.h
new file mode 100644
index 000000000..45290177a
--- /dev/null
+++ b/include/net/route.h
@@ -0,0 +1,432 @@
+/* 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.
+ *
+ *		Definitions for the IP router.
+ *
+ * Version:	@(#)route.h	1.0.4	05/27/93
+ *
+ * Authors:	Ross Biro
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ * Fixes:
+ *		Alan Cox	:	Reformatted. Added ip_rt_local()
+ *		Alan Cox	:	Support for TCP parameters.
+ *		Alexey Kuznetsov:	Major changes for new routing code.
+ *		Mike McLagan    :	Routing by source
+ *		Robert Olsson   :	Added rt_cache statistics
+ */
+#ifndef _ROUTE_H
+#define _ROUTE_H
+
+#include <net/dst.h>
+#include <net/inetpeer.h>
+#include <net/flow.h>
+#include <net/inet_sock.h>
+#include <net/ip_fib.h>
+#include <net/arp.h>
+#include <net/ndisc.h>
+#include <net/inet_dscp.h>
+#include <net/sock.h>
+#include <linux/in_route.h>
+#include <linux/rtnetlink.h>
+#include <linux/rcupdate.h>
+#include <linux/route.h>
+#include <linux/ip.h>
+#include <linux/cache.h>
+#include <linux/security.h>
+
+static inline __u8 ip_sock_rt_scope(const struct sock *sk)
+{
+	if (sock_flag(sk, SOCK_LOCALROUTE))
+		return RT_SCOPE_LINK;
+
+	return RT_SCOPE_UNIVERSE;
+}
+
+static inline __u8 ip_sock_rt_tos(const struct sock *sk)
+{
+	return READ_ONCE(inet_sk(sk)->tos) & INET_DSCP_MASK;
+}
+
+struct ip_tunnel_info;
+struct fib_nh;
+struct fib_info;
+struct uncached_list;
+struct rtable {
+	struct dst_entry	dst;
+
+	int			rt_genid;
+	unsigned int		rt_flags;
+	__u16			rt_type;
+	__u8			rt_is_input;
+	__u8			rt_uses_gateway;
+
+	int			rt_iif;
+
+	u8			rt_gw_family;
+	/* Info on neighbour */
+	union {
+		__be32		rt_gw4;
+		struct in6_addr	rt_gw6;
+	};
+
+	/* Miscellaneous cached information */
+	u32			rt_mtu_locked:1,
+				rt_pmtu:31;
+};
+
+#define dst_rtable(_ptr) container_of_const(_ptr, struct rtable, dst)
+
+/**
+ * skb_rtable - Returns the skb &rtable
+ * @skb: buffer
+ */
+static inline struct rtable *skb_rtable(const struct sk_buff *skb)
+{
+	return dst_rtable(skb_dst(skb));
+}
+
+static inline bool rt_is_input_route(const struct rtable *rt)
+{
+	return rt->rt_is_input != 0;
+}
+
+static inline bool rt_is_output_route(const struct rtable *rt)
+{
+	return rt->rt_is_input == 0;
+}
+
+static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
+{
+	if (rt->rt_gw_family == AF_INET)
+		return rt->rt_gw4;
+	return daddr;
+}
+
+struct ip_rt_acct {
+	__u32 	o_bytes;
+	__u32 	o_packets;
+	__u32 	i_bytes;
+	__u32 	i_packets;
+};
+
+struct rt_cache_stat {
+        unsigned int in_slow_tot;
+        unsigned int in_slow_mc;
+        unsigned int in_no_route;
+        unsigned int in_brd;
+        unsigned int in_martian_dst;
+        unsigned int in_martian_src;
+        unsigned int out_slow_tot;
+        unsigned int out_slow_mc;
+};
+
+extern struct ip_rt_acct __percpu *ip_rt_acct;
+
+struct in_device;
+
+int ip_rt_init(void);
+void rt_cache_flush(struct net *net);
+void rt_flush_dev(struct net_device *dev);
+
+static inline void inet_sk_init_flowi4(const struct inet_sock *inet,
+				       struct flowi4 *fl4)
+{
+	const struct ip_options_rcu *ip4_opt;
+	const struct sock *sk;
+	__be32 daddr;
+
+	rcu_read_lock();
+	ip4_opt = rcu_dereference(inet->inet_opt);
+
+	/* Source routing option overrides the socket destination address */
+	if (ip4_opt && ip4_opt->opt.srr)
+		daddr = ip4_opt->opt.faddr;
+	else
+		daddr = inet->inet_daddr;
+	rcu_read_unlock();
+
+	sk = &inet->sk;
+	flowi4_init_output(fl4, sk->sk_bound_dev_if, READ_ONCE(sk->sk_mark),
+			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
+			   sk->sk_protocol, inet_sk_flowi_flags(sk), daddr,
+			   inet->inet_saddr, inet->inet_dport,
+			   inet->inet_sport, sk_uid(sk));
+	security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
+}
+
+struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *flp,
+					const struct sk_buff *skb);
+struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *flp,
+					    struct fib_result *res,
+					    const struct sk_buff *skb);
+
+static inline struct rtable *__ip_route_output_key(struct net *net,
+						   struct flowi4 *flp)
+{
+	return ip_route_output_key_hash(net, flp, NULL);
+}
+
+struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
+				    const struct sock *sk);
+struct dst_entry *ipv4_blackhole_route(struct net *net,
+				       struct dst_entry *dst_orig);
+
+static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
+{
+	return ip_route_output_flow(net, flp, NULL);
+}
+
+/* Simplistic IPv4 route lookup function.
+ * This is only suitable for some particular use cases: since the flowi4
+ * structure is only partially set, it may bypass some fib-rules.
+ */
+static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
+					     __be32 saddr, dscp_t dscp,
+					     int oif, __u8 scope)
+{
+	struct flowi4 fl4 = {
+		.flowi4_oif = oif,
+		.flowi4_dscp = dscp,
+		.flowi4_scope = scope,
+		.daddr = daddr,
+		.saddr = saddr,
+	};
+
+	return ip_route_output_key(net, &fl4);
+}
+
+static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
+						   const struct sock *sk,
+						   __be32 daddr, __be32 saddr,
+						   __be16 dport, __be16 sport,
+						   __u8 proto, __u8 tos, int oif)
+{
+	flowi4_init_output(fl4, oif, sk ? READ_ONCE(sk->sk_mark) : 0, tos,
+			   sk ? ip_sock_rt_scope(sk) : RT_SCOPE_UNIVERSE,
+			   proto, sk ? inet_sk_flowi_flags(sk) : 0,
+			   daddr, saddr, dport, sport, sock_net_uid(net, sk));
+	if (sk)
+		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
+	return ip_route_output_flow(net, fl4, sk);
+}
+
+enum skb_drop_reason
+ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+		      dscp_t dscp, struct net_device *dev,
+		      struct in_device *in_dev, u32 *itag);
+enum skb_drop_reason
+ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+		     dscp_t dscp, struct net_device *dev);
+enum skb_drop_reason
+ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+		  dscp_t dscp, struct net_device *dev,
+		  const struct sk_buff *hint);
+
+static inline enum skb_drop_reason
+ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src, dscp_t dscp,
+	       struct net_device *devin)
+{
+	enum skb_drop_reason reason;
+
+	rcu_read_lock();
+	reason = ip_route_input_noref(skb, dst, src, dscp, devin);
+	if (!reason) {
+		skb_dst_force(skb);
+		if (!skb_dst(skb))
+			reason = SKB_DROP_REASON_NOT_SPECIFIED;
+	}
+	rcu_read_unlock();
+
+	return reason;
+}
+
+void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
+		      u8 protocol);
+void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
+void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u8 protocol);
+void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
+void ip_rt_send_redirect(struct sk_buff *skb);
+
+unsigned int inet_addr_type(struct net *net, __be32 addr);
+unsigned int inet_addr_type_table(struct net *net, __be32 addr, u32 tb_id);
+unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
+				__be32 addr);
+unsigned int inet_addr_type_dev_table(struct net *net,
+				      const struct net_device *dev,
+				      __be32 addr);
+void ip_rt_multicast_event(struct in_device *);
+int ip_rt_ioctl(struct net *, unsigned int cmd, struct rtentry *rt);
+void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
+struct rtable *rt_dst_alloc(struct net_device *dev,
+			    unsigned int flags, u16 type, bool noxfrm);
+struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt);
+
+struct in_ifaddr;
+void fib_add_ifaddr(struct in_ifaddr *);
+void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
+void fib_modify_prefix_metric(struct in_ifaddr *ifa, u32 new_metric);
+
+void rt_add_uncached_list(struct rtable *rt);
+void rt_del_uncached_list(struct rtable *rt);
+
+int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
+		       u32 table_id, struct fib_info *fi,
+		       int *fa_index, int fa_start, unsigned int flags);
+
+void fnhe_update_pmtu(struct fib_nh_exception *fnhe, u32 new, u32 orig);
+
+static inline void ip_rt_put(struct rtable *rt)
+{
+	/* dst_release() accepts a NULL parameter.
+	 * We rely on dst being first structure in struct rtable
+	 */
+	BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
+	dst_release(&rt->dst);
+}
+
+extern const __u8 ip_tos2prio[16];
+
+static inline char rt_tos2priority(u8 tos)
+{
+	return ip_tos2prio[IPTOS_TOS(tos)>>1];
+}
+
+/* ip_route_connect() and ip_route_newports() work in tandem whilst
+ * binding a socket for a new outgoing connection.
+ *
+ * In order to use IPSEC properly, we must, in the end, have a
+ * route that was looked up using all available keys including source
+ * and destination ports.
+ *
+ * However, if a source port needs to be allocated (the user specified
+ * a wildcard source port) we need to obtain addressing information
+ * in order to perform that allocation.
+ *
+ * So ip_route_connect() looks up a route using wildcarded source and
+ * destination ports in the key, simply so that we can get a pair of
+ * addresses to use for port allocation.
+ *
+ * Later, once the ports are allocated, ip_route_newports() will make
+ * another route lookup if needed to make sure we catch any IPSEC
+ * rules keyed on the port information.
+ *
+ * The callers allocate the flow key on their stack, and must pass in
+ * the same flowi4 object to both the ip_route_connect() and the
+ * ip_route_newports() calls.
+ */
+
+static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst,
+					 __be32 src, int oif, u8 protocol,
+					 __be16 sport, __be16 dport,
+					 const struct sock *sk)
+{
+	__u8 flow_flags = 0;
+
+	if (inet_test_bit(TRANSPARENT, sk))
+		flow_flags |= FLOWI_FLAG_ANYSRC;
+
+	if (IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) && !sport)
+		flow_flags |= FLOWI_FLAG_ANY_SPORT;
+
+	flowi4_init_output(fl4, oif, READ_ONCE(sk->sk_mark), ip_sock_rt_tos(sk),
+			   ip_sock_rt_scope(sk), protocol, flow_flags, dst,
+			   src, dport, sport, sk_uid(sk));
+}
+
+static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
+					      __be32 src, int oif, u8 protocol,
+					      __be16 sport, __be16 dport,
+					      const struct sock *sk)
+{
+	struct net *net = sock_net(sk);
+	struct rtable *rt;
+
+	ip_route_connect_init(fl4, dst, src, oif, protocol, sport, dport, sk);
+
+	if (!dst || !src) {
+		rt = __ip_route_output_key(net, fl4);
+		if (IS_ERR(rt))
+			return rt;
+		ip_rt_put(rt);
+		flowi4_update_output(fl4, oif, fl4->daddr, fl4->saddr);
+	}
+	security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
+	return ip_route_output_flow(net, fl4, sk);
+}
+
+static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
+					       __be16 orig_sport, __be16 orig_dport,
+					       __be16 sport, __be16 dport,
+					       const struct sock *sk)
+{
+	if (sport != orig_sport || dport != orig_dport) {
+		fl4->fl4_dport = dport;
+		fl4->fl4_sport = sport;
+		ip_rt_put(rt);
+		flowi4_update_output(fl4, sk->sk_bound_dev_if, fl4->daddr,
+				     fl4->saddr);
+		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
+		return ip_route_output_flow(sock_net(sk), fl4, sk);
+	}
+	return rt;
+}
+
+static inline int inet_iif(const struct sk_buff *skb)
+{
+	struct rtable *rt = skb_rtable(skb);
+
+	if (rt && rt->rt_iif)
+		return rt->rt_iif;
+
+	return skb->skb_iif;
+}
+
+static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
+{
+	int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
+
+	if (hoplimit == 0) {
+		const struct net *net;
+
+		rcu_read_lock();
+		net = dst_dev_net_rcu(dst);
+		hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
+		rcu_read_unlock();
+	}
+	return hoplimit;
+}
+
+static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
+					     __be32 daddr)
+{
+	struct neighbour *neigh;
+
+	neigh = __ipv4_neigh_lookup_noref(dev, (__force u32)daddr);
+	if (unlikely(!neigh))
+		neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
+
+	return neigh;
+}
+
+static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
+						struct sk_buff *skb,
+						bool *is_v6gw)
+{
+	struct net_device *dev = rt->dst.dev;
+	struct neighbour *neigh;
+
+	if (likely(rt->rt_gw_family == AF_INET)) {
+		neigh = ip_neigh_gw4(dev, rt->rt_gw4);
+	} else if (rt->rt_gw_family == AF_INET6) {
+		neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
+		*is_v6gw = true;
+	} else {
+		neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
+	}
+	return neigh;
+}
+
+#endif	/* _ROUTE_H */