bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/lib/crypto/chacha.c b/lib/crypto/chacha.c
new file mode 100644
index 000000000..86e5d382a
--- /dev/null
+++ b/lib/crypto/chacha.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The ChaCha stream cipher (RFC7539)
+ *
+ * Copyright (C) 2015 Martin Willi
+ */
+
+#include <crypto/chacha.h>
+#include <crypto/utils.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+static void __maybe_unused
+chacha_crypt_generic(struct chacha_state *state, u8 *dst, const u8 *src,
+		     unsigned int bytes, int nrounds)
+{
+	/* aligned to potentially speed up crypto_xor() */
+	u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
+
+	while (bytes >= CHACHA_BLOCK_SIZE) {
+		chacha_block_generic(state, stream, nrounds);
+		crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
+		bytes -= CHACHA_BLOCK_SIZE;
+		dst += CHACHA_BLOCK_SIZE;
+		src += CHACHA_BLOCK_SIZE;
+	}
+	if (bytes) {
+		chacha_block_generic(state, stream, nrounds);
+		crypto_xor_cpy(dst, src, stream, bytes);
+	}
+}
+
+#ifdef CONFIG_CRYPTO_LIB_CHACHA_ARCH
+#include "chacha.h" /* $(SRCARCH)/chacha.h */
+#else
+#define chacha_crypt_arch chacha_crypt_generic
+#define hchacha_block_arch hchacha_block_generic
+#endif
+
+void chacha_crypt(struct chacha_state *state, u8 *dst, const u8 *src,
+		  unsigned int bytes, int nrounds)
+{
+	chacha_crypt_arch(state, dst, src, bytes, nrounds);
+}
+EXPORT_SYMBOL_GPL(chacha_crypt);
+
+void hchacha_block(const struct chacha_state *state,
+		   u32 out[HCHACHA_OUT_WORDS], int nrounds)
+{
+	hchacha_block_arch(state, out, nrounds);
+}
+EXPORT_SYMBOL_GPL(hchacha_block);
+
+#ifdef chacha_mod_init_arch
+static int __init chacha_mod_init(void)
+{
+	chacha_mod_init_arch();
+	return 0;
+}
+subsys_initcall(chacha_mod_init);
+
+static void __exit chacha_mod_exit(void)
+{
+}
+module_exit(chacha_mod_exit);
+#endif
+
+MODULE_DESCRIPTION("ChaCha stream cipher (RFC7539)");
+MODULE_LICENSE("GPL");