Restore PGREQUIRESSL recognition in libpq.

nmisch · nmisch · commit 3eab8112754c · 2017-05-08T07:24:28.000-07:00
Commit 65c3bf1 moved handling of the, already then, deprecated requiressl parameter into conninfo_storeval(). The default PGREQUIRESSL environment variable was however lost in the change resulting in a potentially silent accept of a non-SSL connection even when set. Its documentation remained. Restore its implementation. Also amend the documentation to mark PGREQUIRESSL as deprecated for those not following the link to requiressl. Back-patch to 9.3, where commit 65c3bf1 first appeared. Behavior has been more complex when the user provides both deprecated and non-deprecated settings. Before commit 65c3bf1, libpq operated according to the first of these found: requiressl=1 PGREQUIRESSL=1 sslmode=* PGSSLMODE=* (Note requiressl=0 didn't override sslmode=*; it would only suppress PGREQUIRESSL=1 or a previous requiressl=1. PGREQUIRESSL=0 had no effect whatsoever.) Starting with commit 65c3bf1, libpq ignored PGREQUIRESSL, and order of precedence changed to this: last of requiressl=* or sslmode=* PGSSLMODE=* Starting now, adopt the following order of precedence: last of requiressl=* or sslmode=* PGSSLMODE=* PGREQUIRESSL=1 This retains the 65c3bf1 behavior for connection strings that contain both requiressl=* and sslmode=*. It retains the 65c3bf1 change that either connection string option overrides both environment variables. For the first time, PGSSLMODE has precedence over PGREQUIRESSL; this avoids reducing security of "PGREQUIRESSL=1 PGSSLMODE=verify-full" configurations originating under v9.3 and later. Daniel Gustafsson Security: CVE-2017-7485
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
@@ -6710,6 +6710,9 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough)
       </indexterm>
       <envar>PGREQUIRESSL</envar> behaves the same as the <xref
       linkend="libpq-connect-requiressl"> connection parameter.
+      This environment variable is deprecated in favor of the
+      <envar>PGSSLMODE</envar> variable; setting both variables suppresses the
+      effect of this one.
      </para>
     </listitem>
 
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
@@ -4608,6 +4608,30 @@ conninfo_add_defaults(PQconninfoOption *options, PQExpBuffer errorMessage)
 			}
 		}
 
+		/*
+		 * Interpret the deprecated PGREQUIRESSL environment variable.  Per
+		 * tradition, translate values starting with "1" to sslmode=require,
+		 * and ignore other values.  Given both PGREQUIRESSL=1 and PGSSLMODE,
+		 * PGSSLMODE takes precedence; the opposite was true before v9.3.
+		 */
+		if (strcmp(option->keyword, "sslmode") == 0)
+		{
+			const char *requiresslenv = getenv("PGREQUIRESSL");
+
+			if (requiresslenv != NULL && requiresslenv[0] == '1')
+			{
+				option->val = strdup("require");
+				if (!option->val)
+				{
+					if (errorMessage)
+						printfPQExpBuffer(errorMessage,
+										  libpq_gettext("out of memory\n"));
+					return false;
+				}
+				continue;
+			}
+		}
+
 		/*
 		 * No environment variable specified or the variable isn't set - try
 		 * compiled-in default
