From f66a211e8c5d9b1b0531364c1b16874b0499e0d2 Mon Sep 17 00:00:00 2001
From: Herbert Xu
Date: Wed, 21 Feb 2024 13:19:15 +0800
Subject: crypto: dh - Make public key test FIPS-only

The function dh_is_pubkey_valid was added to for FIPS but it was
only partially conditional to fips_enabled.

In particular, the first test in the function relies on the last
test to work properly, but the last test is only run in FIPS mode.

Fix this inconsistency by making the whole function conditional
on fips_enabled.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/dh.c | 57 +++++++++++++++++++++++++++++----------------------------
 1 file changed, 29 insertions(+), 28 deletions(-)

diff --git a/crypto/dh.c b/crypto/dh.c
index 0fcad279e6fe..68d11d66c0b5 100644
--- a/crypto/dh.c
+++ b/crypto/dh.c
@@ -106,6 +106,12 @@ err_clear_ctx:
  */
 static int dh_is_pubkey_valid(struct dh_ctx *ctx, MPI y)
 {
+	MPI val, q;
+	int ret;
+
+	if (!fips_enabled)
+		return 0;
+
 	if (unlikely(!ctx->p))
 		return -EINVAL;
 
@@ -125,40 +131,35 @@ static int dh_is_pubkey_valid(struct dh_ctx *ctx, MPI y)
 	 *
 	 * For the safe-prime groups q = (p - 1)/2.
 	 */
-	if (fips_enabled) {
-		MPI val, q;
-		int ret;
+	val = mpi_alloc(0);
+	if (!val)
+		return -ENOMEM;
 
-		val = mpi_alloc(0);
-		if (!val)
-			return -ENOMEM;
+	q = mpi_alloc(mpi_get_nlimbs(ctx->p));
+	if (!q) {
+		mpi_free(val);
+		return -ENOMEM;
+	}
 
-		q = mpi_alloc(mpi_get_nlimbs(ctx->p));
-		if (!q) {
-			mpi_free(val);
-			return -ENOMEM;
-		}
+	/*
+	 * ->p is odd, so no need to explicitly subtract one
+	 * from it before shifting to the right.
+	 */
+	mpi_rshift(q, ctx->p, 1);
 
-		/*
-		 * ->p is odd, so no need to explicitly subtract one
-		 * from it before shifting to the right.
-		 */
-		mpi_rshift(q, ctx->p, 1);
-
-		ret = mpi_powm(val, y, q, ctx->p);
-		mpi_free(q);
-		if (ret) {
-			mpi_free(val);
-			return ret;
-		}
+	ret = mpi_powm(val, y, q, ctx->p);
+	mpi_free(q);
+	if (ret) {
+		mpi_free(val);
+		return ret;
+	}
 
-		ret = mpi_cmp_ui(val, 1);
+	ret = mpi_cmp_ui(val, 1);
 
-		mpi_free(val);
+	mpi_free(val);
 
-		if (ret != 0)
-			return -EINVAL;
-	}
+	if (ret != 0)
+		return -EINVAL;
 
 	return 0;
 }
-- 
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