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, 83 insertions, 0 deletions

diff --git a/include/crypto/ecdh.h b/include/crypto/ecdh.h
new file mode 100644
index 000000000..9784ecdd2
--- /dev/null
+++ b/include/crypto/ecdh.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * ECDH params to be used with kpp API
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ */
+#ifndef _CRYPTO_ECDH_
+#define _CRYPTO_ECDH_
+
+/**
+ * DOC: ECDH Helper Functions
+ *
+ * To use ECDH with the KPP cipher API, the following data structure and
+ * functions should be used.
+ *
+ * The ECC curves known to the ECDH implementation are specified in this
+ * header file.
+ *
+ * To use ECDH with KPP, the following functions should be used to operate on
+ * an ECDH private key. The packet private key that can be set with
+ * the KPP API function call of crypto_kpp_set_secret.
+ */
+
+/* Curves IDs */
+#define ECC_CURVE_NIST_P192	0x0001
+#define ECC_CURVE_NIST_P256	0x0002
+#define ECC_CURVE_NIST_P384	0x0003
+#define ECC_CURVE_NIST_P521	0x0004
+
+/**
+ * struct ecdh - define an ECDH private key
+ *
+ * @key:	Private ECDH key
+ * @key_size:	Size of the private ECDH key
+ */
+struct ecdh {
+	char *key;
+	unsigned short key_size;
+};
+
+/**
+ * crypto_ecdh_key_len() - Obtain the size of the private ECDH key
+ * @params:	private ECDH key
+ *
+ * This function returns the packet ECDH key size. A caller can use that
+ * with the provided ECDH private key reference to obtain the required
+ * memory size to hold a packet key.
+ *
+ * Return: size of the key in bytes
+ */
+unsigned int crypto_ecdh_key_len(const struct ecdh *params);
+
+/**
+ * crypto_ecdh_encode_key() - encode the private key
+ * @buf:	Buffer allocated by the caller to hold the packet ECDH
+ *		private key. The buffer should be at least crypto_ecdh_key_len
+ *		bytes in size.
+ * @len:	Length of the packet private key buffer
+ * @p:		Buffer with the caller-specified private key
+ *
+ * The ECDH implementations operate on a packet representation of the private
+ * key.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p);
+
+/**
+ * crypto_ecdh_decode_key() - decode a private key
+ * @buf:	Buffer holding a packet key that should be decoded
+ * @len:	Length of the packet private key buffer
+ * @p:		Buffer allocated by the caller that is filled with the
+ *		unpacked ECDH private key.
+ *
+ * The unpacking obtains the private key by pointing @p to the correct location
+ * in @buf. Thus, both pointers refer to the same memory.
+ *
+ * Return:	-EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p);
+
+#endif