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 --- security/landlock/setup.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 security/landlock/setup.c (limited to 'security/landlock/setup.c') diff --git a/security/landlock/setup.c b/security/landlock/setup.c new file mode 100644 index 000000000..47dac1736 --- /dev/null +++ b/security/landlock/setup.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#include +#include +#include +#include + +#include "common.h" +#include "cred.h" +#include "errata.h" +#include "fs.h" +#include "id.h" +#include "net.h" +#include "setup.h" +#include "task.h" + +bool landlock_initialized __ro_after_init = false; + +const struct lsm_id landlock_lsmid = { + .name = LANDLOCK_NAME, + .id = LSM_ID_LANDLOCK, +}; + +struct lsm_blob_sizes landlock_blob_sizes __ro_after_init = { + .lbs_cred = sizeof(struct landlock_cred_security), + .lbs_file = sizeof(struct landlock_file_security), + .lbs_inode = sizeof(struct landlock_inode_security), + .lbs_superblock = sizeof(struct landlock_superblock_security), +}; + +int landlock_errata __ro_after_init; + +static void __init compute_errata(void) +{ + size_t i; + +#ifndef __has_include + /* + * This is a safeguard to make sure the compiler implements + * __has_include (see errata.h). + */ + WARN_ON_ONCE(1); + return; +#endif + + for (i = 0; landlock_errata_init[i].number; i++) { + const int prev_errata = landlock_errata; + + if (WARN_ON_ONCE(landlock_errata_init[i].abi > + landlock_abi_version)) + continue; + + landlock_errata |= BIT(landlock_errata_init[i].number - 1); + WARN_ON_ONCE(prev_errata == landlock_errata); + } +} + +static int __init landlock_init(void) +{ + compute_errata(); + landlock_add_cred_hooks(); + landlock_add_task_hooks(); + landlock_add_fs_hooks(); + landlock_add_net_hooks(); + landlock_init_id(); + landlock_initialized = true; + pr_info("Up and running.\n"); + return 0; +} + +DEFINE_LSM(LANDLOCK_NAME) = { + .id = &landlock_lsmid, + .init = landlock_init, + .blobs = &landlock_blob_sizes, +}; -- cgit v1.3.1