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, 62 insertions, 0 deletions

diff --git a/include/crypto/mldsa.h b/include/crypto/mldsa.h
new file mode 100644
index 000000000..3ef267678
--- /dev/null
+++ b/include/crypto/mldsa.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Support for verifying ML-DSA signatures
+ *
+ * Copyright 2025 Google LLC
+ */
+#ifndef _CRYPTO_MLDSA_H
+#define _CRYPTO_MLDSA_H
+
+#include <linux/types.h>
+
+/* Identifier for an ML-DSA parameter set */
+enum mldsa_alg {
+	MLDSA44, /* ML-DSA-44 */
+	MLDSA65, /* ML-DSA-65 */
+	MLDSA87, /* ML-DSA-87 */
+};
+
+/* Lengths of ML-DSA public keys and signatures in bytes */
+#define MLDSA44_PUBLIC_KEY_SIZE 1312
+#define MLDSA65_PUBLIC_KEY_SIZE 1952
+#define MLDSA87_PUBLIC_KEY_SIZE 2592
+#define MLDSA44_SIGNATURE_SIZE 2420
+#define MLDSA65_SIGNATURE_SIZE 3309
+#define MLDSA87_SIGNATURE_SIZE 4627
+
+/**
+ * mldsa_verify() - Verify an ML-DSA signature
+ * @alg: The ML-DSA parameter set to use
+ * @sig: The signature
+ * @sig_len: Length of the signature in bytes.  Should match the
+ *	     MLDSA*_SIGNATURE_SIZE constant associated with @alg,
+ *	     otherwise -EBADMSG will be returned.
+ * @msg: The message
+ * @msg_len: Length of the message in bytes
+ * @pk: The public key
+ * @pk_len: Length of the public key in bytes.  Should match the
+ *	    MLDSA*_PUBLIC_KEY_SIZE constant associated with @alg,
+ *	    otherwise -EBADMSG will be returned.
+ *
+ * This verifies a signature using pure ML-DSA with the specified parameter set.
+ * The context string is assumed to be empty.  This corresponds to FIPS 204
+ * Algorithm 3 "ML-DSA.Verify" with the ctx parameter set to the empty string
+ * and the lengths of the signature and key given explicitly by the caller.
+ *
+ * Context: Might sleep
+ *
+ * Return:
+ * * 0 if the signature is valid
+ * * -EBADMSG if the signature and/or public key is malformed
+ * * -EKEYREJECTED if the signature is invalid but otherwise well-formed
+ * * -ENOMEM if out of memory so the validity of the signature is unknown
+ */
+int mldsa_verify(enum mldsa_alg alg, const u8 *sig, size_t sig_len,
+		 const u8 *msg, size_t msg_len, const u8 *pk, size_t pk_len);
+
+#if IS_ENABLED(CONFIG_CRYPTO_LIB_MLDSA_KUNIT_TEST)
+/* Internal function, exposed only for unit testing */
+s32 mldsa_use_hint(u8 h, s32 r, s32 gamma2);
+#endif
+
+#endif /* _CRYPTO_MLDSA_H */