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 --- fs/lockd/netlink.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 fs/lockd/netlink.c (limited to 'fs/lockd/netlink.c') diff --git a/fs/lockd/netlink.c b/fs/lockd/netlink.c new file mode 100644 index 000000000..880c42b4f --- /dev/null +++ b/fs/lockd/netlink.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/lockd.yaml */ +/* YNL-GEN kernel source */ +/* To regenerate run: tools/net/ynl/ynl-regen.sh */ + +#include +#include + +#include "netlink.h" + +#include + +/* LOCKD_CMD_SERVER_SET - do */ +static const struct nla_policy lockd_server_set_nl_policy[LOCKD_A_SERVER_UDP_PORT + 1] = { + [LOCKD_A_SERVER_GRACETIME] = { .type = NLA_U32, }, + [LOCKD_A_SERVER_TCP_PORT] = { .type = NLA_U16, }, + [LOCKD_A_SERVER_UDP_PORT] = { .type = NLA_U16, }, +}; + +/* Ops table for lockd */ +static const struct genl_split_ops lockd_nl_ops[] = { + { + .cmd = LOCKD_CMD_SERVER_SET, + .doit = lockd_nl_server_set_doit, + .policy = lockd_server_set_nl_policy, + .maxattr = LOCKD_A_SERVER_UDP_PORT, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, + }, + { + .cmd = LOCKD_CMD_SERVER_GET, + .doit = lockd_nl_server_get_doit, + .flags = GENL_CMD_CAP_DO, + }, +}; + +struct genl_family lockd_nl_family __ro_after_init = { + .name = LOCKD_FAMILY_NAME, + .version = LOCKD_FAMILY_VERSION, + .netnsok = true, + .parallel_ops = true, + .module = THIS_MODULE, + .split_ops = lockd_nl_ops, + .n_split_ops = ARRAY_SIZE(lockd_nl_ops), +}; -- cgit v1.3.1