Make be-secure-common.c more consistent for future SSL implementations

Recent commit 8a3d9425 has introduced be-secure-common.c, which is aimed
at including backend-side APIs that can be used by any SSL
implementation.  The purpose is similar to fe-secure-common.c for the
frontend-side APIs.

However, this has forgotten to include check_ssl_key_file_permissions()
in the move, which causes a double dependency between be-secure.c and
be-secure-openssl.c.

Refactor the code in a more logical way.  This also puts into light an
API which is usable by future SSL implementations for permissions on SSL
key files.

Author: Michael Paquier <michael@paquier.xyz>

src/backend/libpq/be-secure-common.c

@@ -19,6 +19,9 @@
 
 #include "postgres.h"
 
+#include <sys/stat.h>
+#include <unistd.h>
+
 #include "libpq/libpq.h"
 #include "storage/fd.h"
 
@@ -118,3 +121,74 @@ error:
 	pfree(command.data);
 	return len;
 }
+
+
+/*
+ * Check permissions for SSL key files.
+ */
+bool
+check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart)
+{
+	int			loglevel = isServerStart ? FATAL : LOG;
+	struct stat	buf;
+
+	if (stat(ssl_key_file, &buf) != 0)
+	{
+		ereport(loglevel,
+				(errcode_for_file_access(),
+				 errmsg("could not access private key file \"%s\": %m",
+						ssl_key_file)));
+		return false;
+	}
+
+	if (!S_ISREG(buf.st_mode))
+	{
+		ereport(loglevel,
+				(errcode(ERRCODE_CONFIG_FILE_ERROR),
+				 errmsg("private key file \"%s\" is not a regular file",
+						ssl_key_file)));
+		return false;
+	}
+
+	/*
+	 * Refuse to load key files owned by users other than us or root.
+	 *
+	 * XXX surely we can check this on Windows somehow, too.
+	 */
+#if !defined(WIN32) && !defined(__CYGWIN__)
+	if (buf.st_uid != geteuid() && buf.st_uid != 0)
+	{
+		ereport(loglevel,
+				(errcode(ERRCODE_CONFIG_FILE_ERROR),
+				 errmsg("private key file \"%s\" must be owned by the database user or root",
+						ssl_key_file)));
+		return false;
+	}
+#endif
+
+	/*
+	 * Require no public access to key file. If the file is owned by us,
+	 * require mode 0600 or less. If owned by root, require 0640 or less to
+	 * allow read access through our gid, or a supplementary gid that allows
+	 * to read system-wide certificates.
+	 *
+	 * XXX temporarily suppress check when on Windows, because there may not
+	 * be proper support for Unix-y file permissions.  Need to think of a
+	 * reasonable check to apply on Windows.  (See also the data directory
+	 * permission check in postmaster.c)
+	 */
+#if !defined(WIN32) && !defined(__CYGWIN__)
+	if ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||
+		(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))
+	{
+		ereport(loglevel,
+				(errcode(ERRCODE_CONFIG_FILE_ERROR),
+				 errmsg("private key file \"%s\" has group or world access",
+						ssl_key_file),
+				 errdetail("File must have permissions u=rw (0600) or less if owned by the database user, or permissions u=rw,g=r (0640) or less if owned by root.")));
+		return false;
+	}
+#endif
+
+	return true;
+}

src/backend/libpq/be-secure.c

@@ -18,12 +18,10 @@
 
 #include "postgres.h"
 
-#include <sys/stat.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <ctype.h>
 #include <sys/socket.h>
-#include <unistd.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #ifdef HAVE_NETINET_TCP_H
@@ -320,70 +318,3 @@ secure_raw_write(Port *port, const void *ptr, size_t len)
 
 	return n;
 }
-
-bool
-check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart)
-{
-	int			loglevel = isServerStart ? FATAL : LOG;
-	struct stat	buf;
-
-	if (stat(ssl_key_file, &buf) != 0)
-	{
-		ereport(loglevel,
-				(errcode_for_file_access(),
-				 errmsg("could not access private key file \"%s\": %m",
-						ssl_key_file)));
-		return false;
-	}
-
-	if (!S_ISREG(buf.st_mode))
-	{
-		ereport(loglevel,
-				(errcode(ERRCODE_CONFIG_FILE_ERROR),
-				 errmsg("private key file \"%s\" is not a regular file",
-						ssl_key_file)));
-		return false;
-	}
-
-	/*
-	 * Refuse to load key files owned by users other than us or root.
-	 *
-	 * XXX surely we can check this on Windows somehow, too.
-	 */
-#if !defined(WIN32) && !defined(__CYGWIN__)
-	if (buf.st_uid != geteuid() && buf.st_uid != 0)
-	{
-		ereport(loglevel,
-				(errcode(ERRCODE_CONFIG_FILE_ERROR),
-				 errmsg("private key file \"%s\" must be owned by the database user or root",
-						ssl_key_file)));
-		return false;
-	}
-#endif
-
-	/*
-	 * Require no public access to key file. If the file is owned by us,
-	 * require mode 0600 or less. If owned by root, require 0640 or less to
-	 * allow read access through our gid, or a supplementary gid that allows
-	 * to read system-wide certificates.
-	 *
-	 * XXX temporarily suppress check when on Windows, because there may not
-	 * be proper support for Unix-y file permissions.  Need to think of a
-	 * reasonable check to apply on Windows.  (See also the data directory
-	 * permission check in postmaster.c)
-	 */
-#if !defined(WIN32) && !defined(__CYGWIN__)
-	if ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||
-		(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))
-	{
-		ereport(loglevel,
-				(errcode(ERRCODE_CONFIG_FILE_ERROR),
-				 errmsg("private key file \"%s\" has group or world access",
-						ssl_key_file),
-				 errdetail("File must have permissions u=rw (0600) or less if owned by the database user, or permissions u=rw,g=r (0640) or less if owned by root.")));
-		return false;
-	}
-#endif
-
-	return true;
-}

src/include/libpq/libpq.h

@@ -92,7 +92,6 @@ extern ssize_t secure_read(Port *port, void *ptr, size_t len);
 extern ssize_t secure_write(Port *port, void *ptr, size_t len);
 extern ssize_t secure_raw_read(Port *port, void *ptr, size_t len);
 extern ssize_t secure_raw_write(Port *port, const void *ptr, size_t len);
-extern bool check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart);
 
 extern bool ssl_loaded_verify_locations;
 
@@ -108,5 +107,7 @@ extern bool SSLPreferServerCiphers;
  */
 extern int run_ssl_passphrase_command(const char *prompt, bool is_server_start,
 									  char *buf, int size);
+extern bool check_ssl_key_file_permissions(const char *ssl_key_file,
+										   bool isServerStart);
 
 #endif							/* LIBPQ_H */