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/mpls.h | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 include/net/mpls.h (limited to 'include/net/mpls.h') diff --git a/include/net/mpls.h b/include/net/mpls.h new file mode 100644 index 000000000..0bb7944e7 --- /dev/null +++ b/include/net/mpls.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2014 Nicira, Inc. + */ + +#ifndef _NET_MPLS_H +#define _NET_MPLS_H 1 + +#include +#include +#include + +#define MPLS_HLEN 4 + +struct mpls_shim_hdr { + __be32 label_stack_entry; +}; + +static inline bool eth_p_mpls(__be16 eth_type) +{ + return eth_type == htons(ETH_P_MPLS_UC) || + eth_type == htons(ETH_P_MPLS_MC); +} + +static inline struct mpls_shim_hdr *mpls_hdr(const struct sk_buff *skb) +{ + return (struct mpls_shim_hdr *)skb_network_header(skb); +} + +static inline struct mpls_shim_hdr mpls_entry_encode(u32 label, + unsigned int ttl, + unsigned int tc, + bool bos) +{ + struct mpls_shim_hdr result; + + result.label_stack_entry = + cpu_to_be32((label << MPLS_LS_LABEL_SHIFT) | + (tc << MPLS_LS_TC_SHIFT) | + (bos ? (1 << MPLS_LS_S_SHIFT) : 0) | + (ttl << MPLS_LS_TTL_SHIFT)); + return result; +} + +#endif -- cgit v1.3.1