v2-0001-Reject-incoming-username-and-database-name-in-cas.patch

From 7747032129fb66891805a8a2b5e06cbce8df2d2a Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Wed, 21 Jun 2023 18:28:13 +0000
Subject: [PATCH v2] Reject incoming username and database name in case of
 overlength

---
 src/backend/postmaster/postmaster.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)
 100.0% src/backend/postmaster/

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 4c49393fc5..03289f2093 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2183,9 +2183,25 @@ retry1:
 			valptr = buf + valoffset;
 
 			if (strcmp(nameptr, "database") == 0)
+			{
+				/* Overlength database name has been provided. */
+				if (strlen(valptr) >= NAMEDATALEN)
+					ereport(FATAL,
+							(errcode(ERRCODE_UNDEFINED_DATABASE),
+							 errmsg("database \"%s\" does not exist", valptr)));
+
 				port->database_name = pstrdup(valptr);
+			}
 			else if (strcmp(nameptr, "user") == 0)
+			{
+				/* Overlength user name has been provided. */
+				if (strlen(valptr) >= NAMEDATALEN)
+					ereport(FATAL,
+							(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
+							 errmsg("role \"%s\" does not exist", valptr)));
+
 				port->user_name = pstrdup(valptr);
+			}
 			else if (strcmp(nameptr, "options") == 0)
 				port->cmdline_options = pstrdup(valptr);
 			else if (strcmp(nameptr, "replication") == 0)
@@ -2290,15 +2306,6 @@ retry1:
 		}
 	}
 
-	/*
-	 * Truncate given database and user names to length of a Postgres name.
-	 * This avoids lookup failures when overlength names are given.
-	 */
-	if (strlen(port->database_name) >= NAMEDATALEN)
-		port->database_name[NAMEDATALEN - 1] = '\0';
-	if (strlen(port->user_name) >= NAMEDATALEN)
-		port->user_name[NAMEDATALEN - 1] = '\0';
-
 	if (am_walsender)
 		MyBackendType = B_WAL_SENDER;
 	else
-- 
2.34.1