Subject: [PATCH v1] contrib/sslinfo: Add ssl_(supported|shared)_groups

From: Dmitrii Dolgov <[email-masked]>
Date: Thu, 19 Feb 2026 16:33:17 +0100

Add new functions to sslinfo to show TLS groups extension, both
supported and shared. It's useful for identifying what's being used and
supported, e.g. which key share is being negotiated. Few examples, for
openssl 3.2.4:

    =# select ssl_shared_groups();
     ssl_shared_groups
    -------------------
     x25519:[...]

    =# select ssl_supported_groups();
		ssl_supported_groups
    --------------------------------------
     x25519:[...]

And the same for openssl 3.5 with different defaults:

    =# select ssl_shared_groups();
	    ssl_shared_groups
    ---------------------------------
     X25519MLKEM768:[...]

    =# select ssl_supported_groups();
		ssl_supported_groups
    -------------------------------------
     X25519MLKEM768:[...]

Do not add those functions into the pg_ssl_stats, because they could become
quite large, bloating PgBackendSSLStatus.

The implementation is inspired by ssl_print_groups from openssl.
---
 contrib/sslinfo/Makefile              |  2 +-
 contrib/sslinfo/meson.build           |  3 +-
 contrib/sslinfo/sslinfo--1.2--1.3.sql | 12 ++++++
 contrib/sslinfo/sslinfo--1.3.sql      | 56 ++++++++++++++++++++++++++
 contrib/sslinfo/sslinfo.c             | 31 ++++++++++++++
 contrib/sslinfo/sslinfo.control       |  2 +-
 src/backend/libpq/be-secure-openssl.c | 58 +++++++++++++++++++++++++++
 src/include/libpq/libpq-be.h          |  2 +
 8 files changed, 163 insertions(+), 3 deletions(-)
 create mode 100644 contrib/sslinfo/sslinfo--1.2--1.3.sql
 create mode 100644 contrib/sslinfo/sslinfo--1.3.sql

diff --git a/contrib/sslinfo/Makefile b/contrib/sslinfo/Makefile
index 14305594e2d..d278f02c093 100644
--- a/contrib/sslinfo/Makefile
+++ b/contrib/sslinfo/Makefile
@@ -6,7 +6,7 @@ OBJS = \
 	sslinfo.o
 
 EXTENSION = sslinfo
-DATA = sslinfo--1.2.sql sslinfo--1.1--1.2.sql sslinfo--1.0--1.1.sql
+DATA = sslinfo--1.3.sql sslinfo--1.2--1.3.sql sslinfo--1.1--1.2.sql sslinfo--1.0--1.1.sql
 PGFILEDESC = "sslinfo - information about client SSL certificate"
 
 ifdef USE_PGXS
diff --git a/contrib/sslinfo/meson.build b/contrib/sslinfo/meson.build
index 6e9cb96430a..0258813dde7 100644
--- a/contrib/sslinfo/meson.build
+++ b/contrib/sslinfo/meson.build
@@ -25,7 +25,8 @@ contrib_targets += sslinfo
 install_data(
   'sslinfo--1.0--1.1.sql',
   'sslinfo--1.1--1.2.sql',
-  'sslinfo--1.2.sql',
+  'sslinfo--1.2--1.3.sql',
+  'sslinfo--1.3.sql',
   'sslinfo.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/sslinfo/sslinfo--1.2--1.3.sql b/contrib/sslinfo/sslinfo--1.2--1.3.sql
new file mode 100644
index 00000000000..d2cea79faa7
--- /dev/null
+++ b/contrib/sslinfo/sslinfo--1.2--1.3.sql
@@ -0,0 +1,12 @@
+/* contrib/sslinfo/sslinfo--1.2--1.3.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION sslinfo UPDATE TO '1.3'" to load this file. \quit
+
+CREATE FUNCTION ssl_supported_groups() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_supported_groups'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_shared_groups() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_shared_groups'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
diff --git a/contrib/sslinfo/sslinfo--1.3.sql b/contrib/sslinfo/sslinfo--1.3.sql
new file mode 100644
index 00000000000..98b51900959
--- /dev/null
+++ b/contrib/sslinfo/sslinfo--1.3.sql
@@ -0,0 +1,56 @@
+/* contrib/sslinfo/sslinfo--1.3.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION sslinfo" to load this file. \quit
+
+CREATE FUNCTION ssl_client_serial() RETURNS numeric
+AS 'MODULE_PATHNAME', 'ssl_client_serial'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_is_used() RETURNS boolean
+AS 'MODULE_PATHNAME', 'ssl_is_used'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_version() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_version'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_cipher() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_cipher'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_client_cert_present() RETURNS boolean
+AS 'MODULE_PATHNAME', 'ssl_client_cert_present'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_client_dn_field(text) RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_client_dn_field'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_issuer_field(text) RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_issuer_field'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_client_dn() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_client_dn'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_issuer_dn() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_issuer_dn'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_supported_groups() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_supported_groups'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION ssl_shared_groups() RETURNS text
+AS 'MODULE_PATHNAME', 'ssl_shared_groups'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+CREATE FUNCTION
+ssl_extension_info(OUT name text,
+    OUT value text,
+    OUT critical boolean
+) RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'ssl_extension_info'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
diff --git a/contrib/sslinfo/sslinfo.c b/contrib/sslinfo/sslinfo.c
index 2b9eb90b093..3efdca6d6bc 100644
--- a/contrib/sslinfo/sslinfo.c
+++ b/contrib/sslinfo/sslinfo.c
@@ -88,6 +88,37 @@ ssl_cipher(PG_FUNCTION_ARGS)
 	PG_RETURN_TEXT_P(cstring_to_text(cipher));
 }
 
+PG_FUNCTION_INFO_V1(ssl_supported_groups);
+Datum
+ssl_supported_groups(PG_FUNCTION_ARGS)
+{
+	const char *groups;
+
+	if (!MyProcPort->ssl_in_use)
+		PG_RETURN_NULL();
+
+	groups = be_tls_get_supported_groups(MyProcPort);
+	if (groups == NULL)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(cstring_to_text(groups));
+}
+
+PG_FUNCTION_INFO_V1(ssl_shared_groups);
+Datum
+ssl_shared_groups(PG_FUNCTION_ARGS)
+{
+	const char *groups;
+
+	if (!MyProcPort->ssl_in_use)
+		PG_RETURN_NULL();
+
+	groups = be_tls_get_shared_groups(MyProcPort);
+	if (groups == NULL)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(cstring_to_text(groups));
+}
 
 /*
  * Indicates whether current client provided a certificate
diff --git a/contrib/sslinfo/sslinfo.control b/contrib/sslinfo/sslinfo.control
index c7754f924cf..b53e95b7da8 100644
--- a/contrib/sslinfo/sslinfo.control
+++ b/contrib/sslinfo/sslinfo.control
@@ -1,5 +1,5 @@
 # sslinfo extension
 comment = 'information about SSL certificates'
-default_version = '1.2'
+default_version = '1.3'
 module_pathname = '$libdir/sslinfo'
 relocatable = true
diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c
index 4da6ac22ff9..b134fc53f5f 100644
--- a/src/backend/libpq/be-secure-openssl.c
+++ b/src/backend/libpq/be-secure-openssl.c
@@ -51,6 +51,8 @@
 #endif
 #include <openssl/x509v3.h>
 
+#define SSL_SUPPORTED_GROUPS	0
+#define SSL_SHARED_GROUPS		1
 
 /* default init hook can be overridden by a shared library */
 static void default_openssl_tls_init(SSL_CTX *context, bool isServerStart);
@@ -1560,6 +1562,62 @@ be_tls_get_cipher(Port *port)
 		return NULL;
 }
 
+static const char *
+be_tls_get_groups_internal(Port *port, int type)
+{
+	if (port->ssl)
+	{
+		int i, ngroups, *groups, nid;
+		StringInfoData str;
+
+		if (type == SSL_SUPPORTED_GROUPS)
+			ngroups = SSL_get1_groups(port->ssl, NULL);
+		else
+			ngroups = SSL_get_shared_group(port->ssl, -1);
+
+		if (ngroups <= 0)
+			return NULL;
+
+		groups = palloc(ngroups * sizeof(*groups));
+		initStringInfo(&str);
+
+		if (type == SSL_SUPPORTED_GROUPS)
+			SSL_get1_groups(port->ssl, groups);
+
+		for (i = 0; i < ngroups; i++)
+		{
+			const char *name;
+
+			if (i)
+				appendStringInfo(&str, ":");
+
+			if (type == SSL_SUPPORTED_GROUPS)
+				nid = groups[i];
+			else
+				nid = SSL_get_shared_group(port->ssl, i);
+
+			name = SSL_group_to_name(port->ssl, nid);
+			appendStringInfoString(&str, ((name != NULL) ? name : "(null)"));
+		}
+
+		return str.data;
+	}
+	else
+		return NULL;
+}
+
+const char *
+be_tls_get_supported_groups(Port *port)
+{
+	return be_tls_get_groups_internal(port, SSL_SUPPORTED_GROUPS);
+}
+
+const char *
+be_tls_get_shared_groups(Port *port)
+{
+	return be_tls_get_groups_internal(port, SSL_SHARED_GROUPS);
+}
+
 void
 be_tls_get_peer_subject_name(Port *port, char *ptr, size_t len)
 {
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
index 921b2daa4ff..23e11fcb89d 100644
--- a/src/include/libpq/libpq-be.h
+++ b/src/include/libpq/libpq-be.h
@@ -317,6 +317,8 @@ extern ssize_t be_tls_write(Port *port, const void *ptr, size_t len, int *waitfo
 extern int	be_tls_get_cipher_bits(Port *port);
 extern const char *be_tls_get_version(Port *port);
 extern const char *be_tls_get_cipher(Port *port);
+extern const char *be_tls_get_supported_groups(Port *port);
+extern const char *be_tls_get_shared_groups(Port *port);
 extern void be_tls_get_peer_subject_name(Port *port, char *ptr, size_t len);
 extern void be_tls_get_peer_issuer_name(Port *port, char *ptr, size_t len);
 extern void be_tls_get_peer_serial(Port *port, char *ptr, size_t len);

base-commit: 5b93a5987bd704d2363295eee919eee45f84c286
-- 
2.52.0

--ymr2ng6a3l6bfm2s--