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, 71 insertions, 0 deletions

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
new file mode 100644
index 000000000..8ec1a3436
--- /dev/null
+++ b/security/integrity/iint.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2008 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ *
+ * File: integrity_iint.c
+ *	- initialize the integrity directory in securityfs
+ *	- load IMA and EVM keys
+ */
+#include <linux/security.h>
+#include "integrity.h"
+
+struct dentry *integrity_dir;
+
+/*
+ * integrity_kernel_read - read data from the file
+ *
+ * This is a function for reading file content instead of kernel_read().
+ * It does not perform locking checks to ensure it cannot be blocked.
+ * It does not perform security checks because it is irrelevant for IMA.
+ *
+ */
+int integrity_kernel_read(struct file *file, loff_t offset,
+			  void *addr, unsigned long count)
+{
+	return __kernel_read(file, addr, count, &offset);
+}
+
+/*
+ * integrity_load_keys - load integrity keys hook
+ *
+ * Hooks is called from init/main.c:kernel_init_freeable()
+ * when rootfs is ready
+ */
+void __init integrity_load_keys(void)
+{
+	ima_load_x509();
+
+	if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
+		evm_load_x509();
+}
+
+int __init integrity_fs_init(void)
+{
+	if (integrity_dir)
+		return 0;
+
+	integrity_dir = securityfs_create_dir("integrity", NULL);
+	if (IS_ERR(integrity_dir)) {
+		int ret = PTR_ERR(integrity_dir);
+
+		if (ret != -ENODEV)
+			pr_err("Unable to create integrity sysfs dir: %d\n",
+			       ret);
+		integrity_dir = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+void __init integrity_fs_fini(void)
+{
+	if (!integrity_dir || !simple_empty(integrity_dir))
+		return;
+
+	securityfs_remove(integrity_dir);
+	integrity_dir = NULL;
+}