Here is a patch that adds a way to specify an external command for
obtaining SSL passphrases. There is a new GUC setting
ssl_passphrase_command.
Right now, we rely on the OpenSSL built-in prompting mechanism, which
doesn't work in some situations, including under systemd. This patch
allows a configuration to make that work, e.g., with systemd-ask-password.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From 85dfab5aab956044f89f63edeb0c3cb852c296e5 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Thu, 22 Feb 2018 08:42:18 -0500
Subject: [PATCH] Add ssl_passphrase_command setting
This allows specifying an external command for prompting for or
otherwise obtaining passphrases for SSL key files. This is useful
because in many cases there is no TTY easily available during service
startup.
---
doc/src/sgml/config.sgml | 45 ++++++++++
src/backend/libpq/Makefile | 2 +-
src/backend/libpq/be-secure-common.c | 114 ++++++++++++++++++++++++++
src/backend/libpq/be-secure-openssl.c | 58 +++++++++----
src/backend/libpq/be-secure.c | 1 +
src/backend/utils/misc/guc.c | 10 +++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/include/libpq/libpq.h | 7 ++
src/test/ssl/Makefile | 5 ++
src/test/ssl/README | 3 +
src/test/ssl/ServerSetup.pm | 2 +-
src/test/ssl/ssl/server-password.key | 18 ++++
src/test/ssl/t/001_ssltests.pl | 35 ++++++--
13 files changed, 280 insertions(+), 21 deletions(-)
create mode 100644 src/backend/libpq/be-secure-common.c
create mode 100644 src/test/ssl/ssl/server-password.key
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 4c998fe51f..4b38cb6207 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1312,6 +1312,51 @@ <title>SSL</title>
</para>
</listitem>
</varlistentry>
+
+ <varlistentry id="guc-ssl-passphrase-command"
xreflabel="ssl_passphrase_command">
+ <term><varname>ssl_passphrase_command</varname> (<type>string</type>)
+ <indexterm>
+ <primary><varname>ssl_passphrase_command</varname> configuration
parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Sets an external command to be invoked when a passphrase for
+ decrypting an SSL file such as a private key needs to be obtained. By
+ default, this parameter is empty, which means the built-in prompting
+ mechanism is used.
+ </para>
+ <para>
+ The command must print the passphrase to the standard output and exit
+ with code 0. In the parameter value, <literal>%p</literal> is
+ replaced by a prompt string. (Write <literal>%%</literal> for a
+ literal <literal>%</literal>.) Note that the prompt string will
+ probably contain whitespace, so be sure to quote adequately. A single
+ newline is stripped from the end of the output if present.
+ </para>
+ <para>
+ The command does not actually have to prompt the user for a
+ passphrase. It can read it from a file, obtain it from a keychain
+ facility, or similar. It is up to the user to make sure the chosen
+ mechanism is adequately secure.
+ </para>
+ <para>
+ The passphrase command will also be called during a configuration
+ reload if a key file needs a passphrase. If the setting starts with
+ <literal>-</literal>, then it will be ignored during a reload and the
+ SSL configuration will not be reloaded if a passphrase is needed.
+ (The <literal>-</literal> will not be part of the actual command
+ called.) The latter setting is appropriate for a command that
+ requires a TTY for prompting, which might not be available when the
+ server is running. The default behavior with an empty setting is also
+ not to prompt during a reload.
+ </para>
+ <para>
+ This parameter can only be set in the
<filename>postgresql.conf</filename>
+ file or on the server command line.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
</sect2>
</sect1>
diff --git a/src/backend/libpq/Makefile b/src/backend/libpq/Makefile
index 7fa2b02743..3dbec23e30 100644
--- a/src/backend/libpq/Makefile
+++ b/src/backend/libpq/Makefile
@@ -14,7 +14,7 @@ include $(top_builddir)/src/Makefile.global
# be-fsstubs is here for historical reasons, probably belongs elsewhere
-OBJS = be-fsstubs.o be-secure.o auth.o crypt.o hba.o ifaddr.o pqcomm.o \
+OBJS = be-fsstubs.o be-secure.o be-secure-common.o auth.o crypt.o hba.o
ifaddr.o pqcomm.o \
pqformat.o pqmq.o pqsignal.o auth-scram.o
ifeq ($(with_openssl),yes)
diff --git a/src/backend/libpq/be-secure-common.c
b/src/backend/libpq/be-secure-common.c
new file mode 100644
index 0000000000..a23ba27abc
--- /dev/null
+++ b/src/backend/libpq/be-secure-common.c
@@ -0,0 +1,114 @@
+/*-------------------------------------------------------------------------
+ *
+ * be-secure-common.c
+ *
+ * common implementation-independent SSL support code
+ *
+ * While be-secure.c contains the interfaces that the rest of the
+ * communications code calls, this file contains support routines that are
+ * used by the library-specific implementations such as be-secure-openssl.c.
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/backend/libpq/be-secure-common.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "libpq/libpq.h"
+#include "storage/fd.h"
+
+/*
+ * Run ssl_passphrase_command
+ *
+ * prompt will be substituted for %p. is_server_start determines the loglevel
+ * of error messages.
+ *
+ * The result will be put in buffer buf, which is of size size. The return
+ * value is the length of the actual result.
+ */
+int
+run_ssl_passphrase_command(const char *prompt, bool is_server_start, char
*buf, int size)
+{
+ int loglevel = is_server_start ? ERROR : LOG;
+ StringInfoData command;
+ char *p;
+ FILE *fh;
+ int pclose_rc;
+ size_t len = 0;
+
+ Assert(prompt);
+ Assert(size > 0);
+ buf[0] = '\0';
+
+ initStringInfo(&command);
+
+ p = ssl_passphrase_command;
+
+ if (p[0] == '-')
+ p++;
+
+ for (; *p; p++)
+ {
+ if (p[0] == '%' && p[1] == 'p')
+ {
+ appendStringInfoString(&command, prompt);
+ p++;
+ }
+ else
+ appendStringInfoChar(&command, p[0]);
+ }
+
+ fh = OpenPipeStream(command.data, "r");
+ if (fh == NULL)
+ {
+ ereport(loglevel,
+ (errcode_for_file_access(),
+ errmsg("could not execute command \"%s\": %m",
+ command.data)));
+ goto error;
+ }
+
+ if (!fgets(buf, size, fh))
+ {
+ if (ferror(fh))
+ {
+ ereport(loglevel,
+ (errcode_for_file_access(),
+ errmsg("could not read from command
\"%s\": %m",
+ command.data)));
+ goto error;
+ }
+ }
+
+ pclose_rc = ClosePipeStream(fh);
+ if (pclose_rc == -1)
+ {
+ ereport(loglevel,
+ (errcode_for_file_access(),
+ errmsg("could not close pipe to external
command: %m")));
+ goto error;
+ }
+ else if (pclose_rc != 0)
+ {
+ ereport(loglevel,
+ (errcode_for_file_access(),
+ errmsg("command \"%s\" failed",
+ command.data),
+ errdetail_internal("%s",
wait_result_to_str(pclose_rc))));
+ goto error;
+ }
+
+ /* strip trailing newline */
+ len = strlen(buf);
+ if (buf[len - 1] == '\n')
+ buf[len-- -1] = '\0';
+
+error:
+ pfree(command.data);
+ return len;
+}
diff --git a/src/backend/libpq/be-secure-openssl.c
b/src/backend/libpq/be-secure-openssl.c
index e1ddfb3c16..a7dce2599c 100644
--- a/src/backend/libpq/be-secure-openssl.c
+++ b/src/backend/libpq/be-secure-openssl.c
@@ -52,7 +52,8 @@ static int my_SSL_set_fd(Port *port, int fd);
static DH *load_dh_file(char *filename, bool isServerStart);
static DH *load_dh_buffer(const char *, size_t);
-static int ssl_passwd_cb(char *buf, int size, int rwflag, void *userdata);
+static int ssl_external_passwd_cb(char *buf, int size, int rwflag, void
*userdata);
+static int dummy_ssl_passwd_cb(char *buf, int size, int rwflag, void
*userdata);
static int verify_cb(int, X509_STORE_CTX *);
static void info_cb(const SSL *ssl, int type, int args);
static bool initialize_dh(SSL_CTX *context, bool isServerStart);
@@ -63,7 +64,8 @@ static char *X509_NAME_to_cstring(X509_NAME *name);
static SSL_CTX *SSL_context = NULL;
static bool SSL_initialized = false;
-static bool ssl_passwd_cb_called = false;
+static bool dummy_ssl_passwd_cb_called = false;
+static bool ssl_is_server_start;
/* ------------------------------------------------------------ */
@@ -111,14 +113,28 @@ be_tls_init(bool isServerStart)
SSL_CTX_set_mode(context, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
/*
- * If reloading, override OpenSSL's default handling of
- * passphrase-protected files, because we don't want to prompt for a
- * passphrase in an already-running server. (Not that the default
- * handling is very desirable during server start either, but some
people
- * insist we need to keep it.)
+ * Set password callback
*/
- if (!isServerStart)
- SSL_CTX_set_default_passwd_cb(context, ssl_passwd_cb);
+ if (isServerStart)
+ {
+ if (ssl_passphrase_command[0])
+ SSL_CTX_set_default_passwd_cb(context,
ssl_external_passwd_cb);
+ }
+ else
+ {
+ if (ssl_passphrase_command[0] && ssl_passphrase_command[0] !=
'-')
+ SSL_CTX_set_default_passwd_cb(context,
ssl_external_passwd_cb);
+ else
+ /*
+ * If reloading and no external command is configured,
override
+ * OpenSSL's default handling of passphrase-protected
files,
+ * because we don't want to prompt for a passphrase in
an
+ * already-running server.
+ */
+ SSL_CTX_set_default_passwd_cb(context,
dummy_ssl_passwd_cb);
+ }
+ /* used by the callback */
+ ssl_is_server_start = isServerStart;
/*
* Load and verify server's certificate and private key
@@ -138,13 +154,13 @@ be_tls_init(bool isServerStart)
/*
* OK, try to load the private key file.
*/
- ssl_passwd_cb_called = false;
+ dummy_ssl_passwd_cb_called = false;
if (SSL_CTX_use_PrivateKey_file(context,
ssl_key_file,
SSL_FILETYPE_PEM) != 1)
{
- if (ssl_passwd_cb_called)
+ if (dummy_ssl_passwd_cb_called)
ereport(isServerStart ? FATAL : LOG,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("private key file \"%s\" cannot
be reloaded because it requires a passphrase",
@@ -839,7 +855,21 @@ load_dh_buffer(const char *buffer, size_t len)
}
/*
- * Passphrase collection callback
+ * Passphrase collection callback using ssl_passphrase_command
+ */
+static int
+ssl_external_passwd_cb(char *buf, int size, int rwflag, void *userdata)
+{
+ /* same prompt as OpenSSL uses internally */
+ const char *prompt = "Enter PEM pass phrase:";
+
+ Assert(rwflag == 0);
+
+ return run_ssl_passphrase_command(prompt, ssl_is_server_start, buf,
size);
+}
+
+/*
+ * Dummy passphrase callback
*
* If OpenSSL is told to use a passphrase-protected server key, by default
* it will issue a prompt on /dev/tty and try to read a key from there.
@@ -848,10 +878,10 @@ load_dh_buffer(const char *buffer, size_t len)
* function that just returns an empty passphrase, guaranteeing failure.
*/
static int
-ssl_passwd_cb(char *buf, int size, int rwflag, void *userdata)
+dummy_ssl_passwd_cb(char *buf, int size, int rwflag, void *userdata)
{
/* Set flag to change the error message we'll report */
- ssl_passwd_cb_called = true;
+ dummy_ssl_passwd_cb_called = true;
/* And return empty string */
Assert(size > 0);
buf[0] = '\0';
diff --git a/src/backend/libpq/be-secure.c b/src/backend/libpq/be-secure.c
index 76c0a9e39b..6fb13d4104 100644
--- a/src/backend/libpq/be-secure.c
+++ b/src/backend/libpq/be-secure.c
@@ -45,6 +45,7 @@ char *ssl_key_file;
char *ssl_ca_file;
char *ssl_crl_file;
char *ssl_dh_params_file;
+char *ssl_passphrase_command;
#ifdef USE_SSL
bool ssl_loaded_verify_locations = false;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1db7845d5a..a09cfccdf6 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3654,6 +3654,16 @@ static struct config_string ConfigureNamesString[] =
NULL, NULL, NULL
},
+ {
+ {"ssl_passphrase_command", PGC_SIGHUP, CONN_AUTH_SSL,
+ gettext_noop("Command to obtain passphrases for SSL."),
+ NULL
+ },
+ &ssl_passphrase_command,
+ "",
+ NULL, NULL, NULL
+ },
+
{
{"application_name", PGC_USERSET, LOGGING_WHAT,
gettext_noop("Sets the application name to be reported
in statistics and logs."),
diff --git a/src/backend/utils/misc/postgresql.conf.sample
b/src/backend/utils/misc/postgresql.conf.sample
index 39272925fb..b5ec09ade8 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -104,6 +104,7 @@
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
+#ssl_passphrase_command = ''
#------------------------------------------------------------------------------
diff --git a/src/include/libpq/libpq.h b/src/include/libpq/libpq.h
index 255222acd7..982af998c9 100644
--- a/src/include/libpq/libpq.h
+++ b/src/include/libpq/libpq.h
@@ -80,6 +80,7 @@ extern char *ssl_key_file;
extern char *ssl_ca_file;
extern char *ssl_crl_file;
extern char *ssl_dh_params_file;
+extern char *ssl_passphrase_command;
extern int secure_initialize(bool isServerStart);
extern bool secure_loaded_verify_locations(void);
@@ -101,4 +102,10 @@ extern char *SSLCipherSuites;
extern char *SSLECDHCurve;
extern bool SSLPreferServerCiphers;
+/*
+ * prototypes for functions in be-secure-common.c
+ */
+extern int run_ssl_passphrase_command(const char *prompt, bool is_server_start,
+ char
*buf, int size);
+
#endif /* LIBPQ_H */
diff --git a/src/test/ssl/Makefile b/src/test/ssl/Makefile
index 4e9095529a..fc7ce9b51c 100644
--- a/src/test/ssl/Makefile
+++ b/src/test/ssl/Makefile
@@ -20,6 +20,7 @@ CERTIFICATES := server_ca server-cn-and-alt-names \
root_ca
SSLFILES := $(CERTIFICATES:%=ssl/%.key) $(CERTIFICATES:%=ssl/%.crt) \
+ ssl/server-password.key \
ssl/client.crl ssl/server.crl ssl/root.crl \
ssl/both-cas-1.crt ssl/both-cas-2.crt \
ssl/root+server_ca.crt ssl/root+server.crl \
@@ -69,6 +70,10 @@ ssl/server-ss.crt: ssl/server-cn-only.key
ssl/server-cn-only.crt server-cn-only.
openssl x509 -req -days 10000 -in ssl/server-ss.csr -signkey
ssl/server-cn-only.key -out ssl/server-ss.crt -extensions v3_req -extfile
server-cn-only.config
rm ssl/server-ss.csr
+# Password-protected version of server-cn-only.key
+ssl/server-password.key: ssl/server-cn-only.key
+ openssl rsa -des -in $< -out $@ -passout 'pass:secret1'
+
# Client certificate, signed by the client CA:
ssl/client.crt: ssl/client.key ssl/client_ca.crt
openssl req -new -key ssl/client.key -out ssl/client.csr -config
client.config
diff --git a/src/test/ssl/README b/src/test/ssl/README
index 0be06e755c..5e8bf641ba 100644
--- a/src/test/ssl/README
+++ b/src/test/ssl/README
@@ -48,6 +48,9 @@ server-no-names
server-ss
same as server-cn-only, but self-signed.
+server-password
+ same as server-cn-only, but password-protected.
+
client
a client certificate, for user "ssltestuser". Signed by client_ca.
diff --git a/src/test/ssl/ServerSetup.pm b/src/test/ssl/ServerSetup.pm
index 45991d61a2..75c15d7cfe 100644
--- a/src/test/ssl/ServerSetup.pm
+++ b/src/test/ssl/ServerSetup.pm
@@ -153,7 +153,7 @@ sub switch_server_cert
print $sslconf "ssl_crl_file='root+client.crl'\n";
close $sslconf;
- $node->reload;
+ $node->restart;
}
sub configure_hba_for_ssl
diff --git a/src/test/ssl/ssl/server-password.key
b/src/test/ssl/ssl/server-password.key
new file mode 100644
index 0000000000..adcd38ab88
--- /dev/null
+++ b/src/test/ssl/ssl/server-password.key
@@ -0,0 +1,18 @@
+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: DES-CBC,2FAEFD1C1B2C881C
+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+-----END RSA PRIVATE KEY-----
diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
index e53bd12ae9..300e0f8869 100644
--- a/src/test/ssl/t/001_ssltests.pl
+++ b/src/test/ssl/t/001_ssltests.pl
@@ -2,7 +2,7 @@
use warnings;
use PostgresNode;
use TestLib;
-use Test::More tests => 40;
+use Test::More tests => 42;
use ServerSetup;
use File::Copy;
@@ -21,7 +21,7 @@
copy("ssl/client.key", "ssl/client_tmp.key");
chmod 0600, "ssl/client_tmp.key";
-#### Part 0. Set up the server.
+#### Set up the server.
note "setting up data directory";
my $node = get_new_node('master');
@@ -33,9 +33,32 @@
$ENV{PGPORT} = $node->port;
$node->start;
configure_test_server_for_ssl($node, $SERVERHOSTADDR, 'trust');
-switch_server_cert($node, 'server-cn-only');
-### Part 1. Run client-side tests.
+note "testing password-protected keys";
+
+open my $sslconf, '>', $node->data_dir."/sslconfig.conf";
+print $sslconf "ssl=on\n";
+print $sslconf "ssl_cert_file='server-cn-only.crt'\n";
+print $sslconf "ssl_key_file='server-password.key'\n";
+print $sslconf "ssl_passphrase_command='echo wrongpassword'\n";
+close $sslconf;
+
+command_fails(['pg_ctl', '-D', $node->data_dir, '-l', $node->logfile,
'restart'],
+ 'restart fails with password-protected key file with
wrong password');
+$node->_update_pid(0);
+
+open $sslconf, '>', $node->data_dir."/sslconfig.conf";
+print $sslconf "ssl=on\n";
+print $sslconf "ssl_cert_file='server-cn-only.crt'\n";
+print $sslconf "ssl_key_file='server-password.key'\n";
+print $sslconf "ssl_passphrase_command='echo secret1'\n";
+close $sslconf;
+
+command_ok(['pg_ctl', '-D', $node->data_dir, '-l', $node->logfile, 'restart'],
+ 'restart succeeds with password-protected key file');
+$node->_update_pid(1);
+
+### Run client-side tests.
###
### Test that libpq accepts/rejects the connection correctly, depending
### on sslmode and whether the server's certificate looks correct. No
@@ -43,6 +66,8 @@
note "running client tests";
+switch_server_cert($node, 'server-cn-only');
+
$common_connstr =
"user=ssltestuser dbname=trustdb sslcert=invalid hostaddr=$SERVERHOSTADDR
host=common-name.pg-ssltest.test";
@@ -203,7 +228,7 @@
"sslrootcert=ssl/root+server_ca.crt
sslmode=verify-ca sslcrl=ssl/root+server.crl",
"does not connect with client-side CRL");
-### Part 2. Server-side tests.
+### Server-side tests.
###
### Test certificate authorization.
--
2.16.2
