ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 247 insertions, 0 deletions

diff --git a/crypto/ecdh.c b/crypto/ecdh.c
new file mode 100644
index 000000000..9f0b93b31
--- /dev/null
+++ b/crypto/ecdh.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* ECDH key-agreement protocol
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
+ */
+
+#include <linux/module.h>
+#include <crypto/internal/ecc.h>
+#include <crypto/internal/kpp.h>
+#include <crypto/kpp.h>
+#include <crypto/ecdh.h>
+#include <linux/scatterlist.h>
+
+struct ecdh_ctx {
+	unsigned int curve_id;
+	unsigned int ndigits;
+	u64 private_key[ECC_MAX_DIGITS];
+};
+
+static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
+{
+	return kpp_tfm_ctx(tfm);
+}
+
+static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
+			   unsigned int len)
+{
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+	struct ecdh params;
+	int ret = 0;
+
+	if (crypto_ecdh_decode_key(buf, len, &params) < 0 ||
+	    params.key_size > sizeof(u64) * ctx->ndigits)
+		return -EINVAL;
+
+	memset(ctx->private_key, 0, sizeof(ctx->private_key));
+
+	if (!params.key || !params.key_size)
+		return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
+				       ctx->private_key);
+
+	ecc_digits_from_bytes(params.key, params.key_size,
+			      ctx->private_key, ctx->ndigits);
+
+	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
+			     ctx->private_key, params.key_size) < 0) {
+		memzero_explicit(ctx->private_key, params.key_size);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int ecdh_compute_value(struct kpp_request *req)
+{
+	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+	u64 *public_key;
+	u64 *shared_secret = NULL;
+	void *buf;
+	size_t copied, nbytes, public_key_sz;
+	int ret = -ENOMEM;
+
+	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
+	/* Public part is a point thus it has both coordinates */
+	public_key_sz = 2 * nbytes;
+
+	public_key = kmalloc(public_key_sz, GFP_KERNEL);
+	if (!public_key)
+		return -ENOMEM;
+
+	if (req->src) {
+		shared_secret = kmalloc(nbytes, GFP_KERNEL);
+		if (!shared_secret)
+			goto free_pubkey;
+
+		/* from here on it's invalid parameters */
+		ret = -EINVAL;
+
+		/* must have exactly two points to be on the curve */
+		if (public_key_sz != req->src_len)
+			goto free_all;
+
+		copied = sg_copy_to_buffer(req->src,
+					   sg_nents_for_len(req->src,
+							    public_key_sz),
+					   public_key, public_key_sz);
+		if (copied != public_key_sz)
+			goto free_all;
+
+		ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
+						ctx->private_key, public_key,
+						shared_secret);
+
+		buf = shared_secret;
+	} else {
+		ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
+				       ctx->private_key, public_key);
+		buf = public_key;
+		nbytes = public_key_sz;
+	}
+
+	if (ret < 0)
+		goto free_all;
+
+	/* might want less than we've got */
+	nbytes = min_t(size_t, nbytes, req->dst_len);
+	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
+								nbytes),
+				     buf, nbytes);
+	if (copied != nbytes)
+		ret = -EINVAL;
+
+	/* fall through */
+free_all:
+	kfree_sensitive(shared_secret);
+free_pubkey:
+	kfree(public_key);
+	return ret;
+}
+
+static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
+{
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+
+	/* Public key is made of two coordinates, add one to the left shift */
+	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
+}
+
+static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm)
+{
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+
+	ctx->curve_id = ECC_CURVE_NIST_P192;
+	ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS;
+
+	return 0;
+}
+
+static struct kpp_alg ecdh_nist_p192 = {
+	.set_secret = ecdh_set_secret,
+	.generate_public_key = ecdh_compute_value,
+	.compute_shared_secret = ecdh_compute_value,
+	.max_size = ecdh_max_size,
+	.init = ecdh_nist_p192_init_tfm,
+	.base = {
+		.cra_name = "ecdh-nist-p192",
+		.cra_driver_name = "ecdh-nist-p192-generic",
+		.cra_priority = 100,
+		.cra_module = THIS_MODULE,
+		.cra_ctxsize = sizeof(struct ecdh_ctx),
+	},
+};
+
+static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
+{
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+
+	ctx->curve_id = ECC_CURVE_NIST_P256;
+	ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS;
+
+	return 0;
+}
+
+static struct kpp_alg ecdh_nist_p256 = {
+	.set_secret = ecdh_set_secret,
+	.generate_public_key = ecdh_compute_value,
+	.compute_shared_secret = ecdh_compute_value,
+	.max_size = ecdh_max_size,
+	.init = ecdh_nist_p256_init_tfm,
+	.base = {
+		.cra_name = "ecdh-nist-p256",
+		.cra_driver_name = "ecdh-nist-p256-generic",
+		.cra_priority = 100,
+		.cra_module = THIS_MODULE,
+		.cra_ctxsize = sizeof(struct ecdh_ctx),
+	},
+};
+
+static int ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm)
+{
+	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
+
+	ctx->curve_id = ECC_CURVE_NIST_P384;
+	ctx->ndigits = ECC_CURVE_NIST_P384_DIGITS;
+
+	return 0;
+}
+
+static struct kpp_alg ecdh_nist_p384 = {
+	.set_secret = ecdh_set_secret,
+	.generate_public_key = ecdh_compute_value,
+	.compute_shared_secret = ecdh_compute_value,
+	.max_size = ecdh_max_size,
+	.init = ecdh_nist_p384_init_tfm,
+	.base = {
+		.cra_name = "ecdh-nist-p384",
+		.cra_driver_name = "ecdh-nist-p384-generic",
+		.cra_priority = 100,
+		.cra_module = THIS_MODULE,
+		.cra_ctxsize = sizeof(struct ecdh_ctx),
+	},
+};
+
+static bool ecdh_nist_p192_registered;
+
+static int __init ecdh_init(void)
+{
+	int ret;
+
+	/* NIST p192 will fail to register in FIPS mode */
+	ret = crypto_register_kpp(&ecdh_nist_p192);
+	ecdh_nist_p192_registered = ret == 0;
+
+	ret = crypto_register_kpp(&ecdh_nist_p256);
+	if (ret)
+		goto nist_p256_error;
+
+	ret = crypto_register_kpp(&ecdh_nist_p384);
+	if (ret)
+		goto nist_p384_error;
+
+	return 0;
+
+nist_p384_error:
+	crypto_unregister_kpp(&ecdh_nist_p256);
+
+nist_p256_error:
+	if (ecdh_nist_p192_registered)
+		crypto_unregister_kpp(&ecdh_nist_p192);
+	return ret;
+}
+
+static void __exit ecdh_exit(void)
+{
+	if (ecdh_nist_p192_registered)
+		crypto_unregister_kpp(&ecdh_nist_p192);
+	crypto_unregister_kpp(&ecdh_nist_p256);
+	crypto_unregister_kpp(&ecdh_nist_p384);
+}
+
+module_init(ecdh_init);
+module_exit(ecdh_exit);
+MODULE_ALIAS_CRYPTO("ecdh");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ECDH generic algorithm");