From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- include/net/arp.h | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 include/net/arp.h (limited to 'include/net/arp.h') diff --git a/include/net/arp.h b/include/net/arp.h new file mode 100644 index 000000000..e8747e071 --- /dev/null +++ b/include/net/arp.h @@ -0,0 +1,77 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* linux/net/inet/arp.h */ +#ifndef _ARP_H +#define _ARP_H + +#include +#include +#include + + +extern struct neigh_table arp_tbl; + +static inline u32 arp_hashfn(const void *pkey, const struct net_device *dev, u32 *hash_rnd) +{ + u32 key = *(const u32 *)pkey; + u32 val = key ^ hash32_ptr(dev); + + return val * hash_rnd[0]; +} + +#ifdef CONFIG_INET +static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key) +{ + if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) + key = INADDR_ANY; + + return ___neigh_lookup_noref(&arp_tbl, neigh_key_eq32, arp_hashfn, &key, dev); +} +#else +static inline +struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key) +{ + return NULL; +} +#endif + +static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key) +{ + struct neighbour *n; + + rcu_read_lock(); + n = __ipv4_neigh_lookup_noref(dev, key); + if (n && !refcount_inc_not_zero(&n->refcnt)) + n = NULL; + rcu_read_unlock(); + + return n; +} + +static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) +{ + struct neighbour *n; + + rcu_read_lock(); + n = __ipv4_neigh_lookup_noref(dev, key); + neigh_confirm(n); + rcu_read_unlock(); +} + +void arp_init(void); +int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg); +void arp_send(int type, int ptype, __be32 dest_ip, + struct net_device *dev, __be32 src_ip, + const unsigned char *dest_hw, + const unsigned char *src_hw, const unsigned char *th); +int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir); +void arp_ifdown(struct net_device *dev); +int arp_invalidate(struct net_device *dev, __be32 ip, bool force); + +struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, + struct net_device *dev, __be32 src_ip, + const unsigned char *dest_hw, + const unsigned char *src_hw, + const unsigned char *target_hw); +void arp_xmit(struct sk_buff *skb); + +#endif /* _ARP_H */ -- cgit v1.3.1