From 22d19ff0a54f953caee1c748d9eab96b7c1c299a Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Fri, 7 Aug 2026 16:36:08 +0900
Subject: [PATCH v2] Fetch digests explicitly for cryptohash with OpenSSL 3.0
 and later

cryptohash_openssl.c initialized the EVP_MD_CTX with the implicit static
digest objects (EVP_sha256() and friends), which do not deterministically
dispatch through a loaded provider.

On OpenSSL 3.0 and newer, we now fetch the digest by name with
EVP_MD_fetch(), cache it in the context, and free it on teardown, so
hashing is served by the active provider.  The digest type is fixed for
the lifetime of the context, so the fetch is done once.  The implicit
path is kept for older OpenSSL and for LibreSSL.  OpenSSL 3.0 recommends
to switch from the older APIs to EVP_MD_fetch().
---
 src/common/cryptohash_openssl.c | 46 +++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/src/common/cryptohash_openssl.c b/src/common/cryptohash_openssl.c
index 51b7e0409333..8cab239b4a18 100644
--- a/src/common/cryptohash_openssl.c
+++ b/src/common/cryptohash_openssl.c
@@ -67,6 +67,9 @@ struct pg_cryptohash_ctx
 	const char *errreason;
 
 	EVP_MD_CTX *evpctx;
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	EVP_MD	   *algo;
+#endif
 
 #ifndef FRONTEND
 	ResourceOwner resowner;
@@ -178,10 +181,49 @@ int
 pg_cryptohash_init(pg_cryptohash_ctx *ctx)
 {
 	int			status = 0;
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	const char *name = NULL;
+#endif
 
 	if (ctx == NULL)
 		return -1;
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	/*
+	 * Fetch the digest implementation so that it is served by the loaded
+	 * provider.
+	 */
+	switch (ctx->type)
+	{
+		case PG_MD5:
+			name = "MD5";
+			break;
+		case PG_SHA1:
+			name = "SHA1";
+			break;
+		case PG_SHA224:
+			name = "SHA224";
+			break;
+		case PG_SHA256:
+			name = "SHA256";
+			break;
+		case PG_SHA384:
+			name = "SHA384";
+			break;
+		case PG_SHA512:
+			name = "SHA512";
+			break;
+	}
+
+	/*
+	 * Call EVP_MD_fetch() only once for each context, as provider lookups
+	 * can be expensive.
+	 */
+	if (ctx->algo == NULL)
+		ctx->algo = EVP_MD_fetch(NULL, name, NULL);
+	if (ctx->algo != NULL)
+		status = EVP_DigestInit_ex(ctx->evpctx, ctx->algo, NULL);
+#else
 	switch (ctx->type)
 	{
 		case PG_MD5:
@@ -203,6 +245,7 @@ pg_cryptohash_init(pg_cryptohash_ctx *ctx)
 			status = EVP_DigestInit_ex(ctx->evpctx, EVP_sha512(), NULL);
 			break;
 	}
+#endif
 
 	/* OpenSSL internals return 1 on success, 0 on failure */
 	if (status <= 0)
@@ -329,6 +372,9 @@ pg_cryptohash_free(pg_cryptohash_ctx *ctx)
 		return;
 
 	EVP_MD_CTX_destroy(ctx->evpctx);
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+	EVP_MD_free(ctx->algo);
+#endif
 
 #ifndef FRONTEND
 	if (ctx->resowner)
-- 
2.55.0