From: Michael Paquier Date: Fri, 24 Mar 2023 04:34:26 +0000 (+0900) Subject: libpq: Add sslcertmode option to control client certificates X-Git-Tag: REL_16_BETA1~441 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=36f40ce2dc66f1a36d6a12f7a0352e1c5bf1063e;p=postgresql.git libpq: Add sslcertmode option to control client certificates The sslcertmode option controls whether the server is allowed and/or required to request a certificate from the client. There are three modes: - "allow" is the default and follows the current behavior, where a configured client certificate is sent if the server requests one (via one of its default locations or sslcert). With the current implementation, will happen whenever TLS is negotiated. - "disable" causes the client to refuse to send a client certificate even if sslcert is configured or if a client certificate is available in one of its default locations. - "require" causes the client to fail if a client certificate is never sent and the server opens a connection anyway. This doesn't add any additional security, since there is no guarantee that the server is validating the certificate correctly, but it may helpful to troubleshoot more complicated TLS setups. sslcertmode=require requires SSL_CTX_set_cert_cb(), available since OpenSSL 1.0.2. Note that LibreSSL does not include it. Using a connection parameter different than require_auth has come up as the simplest design because certificate authentication does not rely directly on any of the AUTH_REQ_* codes, and one may want to require a certificate to be sent in combination of a given authentication method, like SCRAM-SHA-256. TAP tests are added in src/test/ssl/, some of them relying on sslinfo to check if a certificate has been set. These are compatible across all the versions of OpenSSL supported on HEAD (currently down to 1.0.1). Author: Jacob Champion Reviewed-by: Aleksander Alekseev, Peter Eisentraut, David G. Johnston, Michael Paquier Discussion: https://postgr.es/m/9e5a8ccddb8355ea9fa4b75a1e3a9edc88a70cd3.camel@vmware.com --- diff --git a/configure b/configure index e221dd5b0ff..905be9568bf 100755 --- a/configure +++ b/configure @@ -12973,13 +12973,15 @@ else fi fi - # Function introduced in OpenSSL 1.0.2. - for ac_func in X509_get_signature_nid + # Functions introduced in OpenSSL 1.0.2. LibreSSL does not have + # SSL_CTX_set_cert_cb(). + for ac_func in X509_get_signature_nid SSL_CTX_set_cert_cb do : - ac_fn_c_check_func "$LINENO" "X509_get_signature_nid" "ac_cv_func_X509_get_signature_nid" -if test "x$ac_cv_func_X509_get_signature_nid" = xyes; then : + as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh` +ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var" +if eval test \"x\$"$as_ac_var"\" = x"yes"; then : cat >>confdefs.h <<_ACEOF -#define HAVE_X509_GET_SIGNATURE_NID 1 +#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1 _ACEOF fi diff --git a/configure.ac b/configure.ac index 3aa6c15c13c..8095dfcf1d1 100644 --- a/configure.ac +++ b/configure.ac @@ -1373,8 +1373,9 @@ if test "$with_ssl" = openssl ; then AC_SEARCH_LIBS(CRYPTO_new_ex_data, [eay32 crypto], [], [AC_MSG_ERROR([library 'eay32' or 'crypto' is required for OpenSSL])]) AC_SEARCH_LIBS(SSL_new, [ssleay32 ssl], [], [AC_MSG_ERROR([library 'ssleay32' or 'ssl' is required for OpenSSL])]) fi - # Function introduced in OpenSSL 1.0.2. - AC_CHECK_FUNCS([X509_get_signature_nid]) + # Functions introduced in OpenSSL 1.0.2. LibreSSL does not have + # SSL_CTX_set_cert_cb(). + AC_CHECK_FUNCS([X509_get_signature_nid SSL_CTX_set_cert_cb]) # Functions introduced in OpenSSL 1.1.0. We used to check for # OPENSSL_VERSION_NUMBER, but that didn't work with 1.1.0, because LibreSSL # defines OPENSSL_VERSION_NUMBER to claim version 2.0.0, even though it diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml index 9ee5532c076..8579dcac952 100644 --- a/doc/src/sgml/libpq.sgml +++ b/doc/src/sgml/libpq.sgml @@ -1810,6 +1810,62 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname + + sslcertmode + + + This option determines whether a client certificate may be sent to the + server, and whether the server is required to request one. There are + three modes: + + + + disable + + + A client certificate is never sent, even if one is available + (default location or provided via + ). + + + + + + allow (default) + + + A certificate may be sent, if the server requests one and the + client has one to send. + + + + + + require + + + The server must request a certificate. The + connection will fail if the client does not send a certificate and + the server successfully authenticates the client anyway. + + + + + + + + + sslcertmode=require doesn't add any additional + security, since there is no guarantee that the server is validating + the certificate correctly; PostgreSQL servers generally request TLS + certificates from clients whether they validate them or not. The + option may be useful when troubleshooting more complicated TLS + setups. + + + + + sslrootcert @@ -7986,6 +8042,16 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough) + + + + PGSSLCERTMODE + + PGSSLCERTMODE behaves the same as the connection parameter. + + + diff --git a/meson.build b/meson.build index 09f619b12fd..77ee015ea9c 100644 --- a/meson.build +++ b/meson.build @@ -1221,8 +1221,9 @@ if sslopt in ['auto', 'openssl'] ['CRYPTO_new_ex_data', {'required': true}], ['SSL_new', {'required': true}], - # Function introduced in OpenSSL 1.0.2. + # Functions introduced in OpenSSL 1.0.2. ['X509_get_signature_nid'], + ['SSL_CTX_set_cert_cb'], # not in LibreSSL # Functions introduced in OpenSSL 1.1.0. We used to check for # OPENSSL_VERSION_NUMBER, but that didn't work with 1.1.0, because LibreSSL diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 4882c705590..3665e799e7b 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -394,6 +394,9 @@ /* Define to 1 if you have spinlocks. */ #undef HAVE_SPINLOCKS +/* Define to 1 if you have the `SSL_CTX_set_cert_cb' function. */ +#undef HAVE_SSL_CTX_SET_CERT_CB + /* Define to 1 if stdbool.h conforms to C99. */ #undef HAVE_STDBOOL_H diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c index fa95f8e6e96..934e3f4f7ca 100644 --- a/src/interfaces/libpq/fe-auth.c +++ b/src/interfaces/libpq/fe-auth.c @@ -798,6 +798,25 @@ check_expected_areq(AuthRequest areq, PGconn *conn) StaticAssertDecl((sizeof(conn->allowed_auth_methods) * CHAR_BIT) > AUTH_REQ_MAX, "AUTH_REQ_MAX overflows the allowed_auth_methods bitmask"); + if (conn->sslcertmode[0] == 'r' /* require */ + && areq == AUTH_REQ_OK) + { + /* + * Trade off a little bit of complexity to try to get these error + * messages as precise as possible. + */ + if (!conn->ssl_cert_requested) + { + libpq_append_conn_error(conn, "server did not request an SSL certificate"); + return false; + } + else if (!conn->ssl_cert_sent) + { + libpq_append_conn_error(conn, "server accepted connection without a valid SSL certificate"); + return false; + } + } + /* * If the user required a specific auth method, or specified an allowed * set, then reject all others here, and make sure the server actually diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index 7d2be566648..660775e0198 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -125,8 +125,10 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options, #define DefaultTargetSessionAttrs "any" #ifdef USE_SSL #define DefaultSSLMode "prefer" +#define DefaultSSLCertMode "allow" #else #define DefaultSSLMode "disable" +#define DefaultSSLCertMode "disable" #endif #ifdef ENABLE_GSS #include "fe-gssapi-common.h" @@ -283,6 +285,10 @@ static const internalPQconninfoOption PQconninfoOptions[] = { "SSL-Client-Key", "", 64, offsetof(struct pg_conn, sslkey)}, + {"sslcertmode", "PGSSLCERTMODE", NULL, NULL, + "SSL-Client-Cert-Mode", "", 8, /* sizeof("disable") == 8 */ + offsetof(struct pg_conn, sslcertmode)}, + {"sslpassword", NULL, NULL, NULL, "SSL-Client-Key-Password", "*", 20, offsetof(struct pg_conn, sslpassword)}, @@ -1506,6 +1512,52 @@ connectOptions2(PGconn *conn) return false; } + /* + * validate sslcertmode option + */ + if (conn->sslcertmode) + { + if (strcmp(conn->sslcertmode, "disable") != 0 && + strcmp(conn->sslcertmode, "allow") != 0 && + strcmp(conn->sslcertmode, "require") != 0) + { + conn->status = CONNECTION_BAD; + libpq_append_conn_error(conn, "invalid %s value: \"%s\"", + "sslcertmode", conn->sslcertmode); + return false; + } +#ifndef USE_SSL + if (strcmp(conn->sslcertmode, "require") == 0) + { + conn->status = CONNECTION_BAD; + libpq_append_conn_error(conn, "%s value \"%s\" invalid when SSL support is not compiled in", + "sslcertmode", conn->sslcertmode); + return false; + } +#endif +#ifndef HAVE_SSL_CTX_SET_CERT_CB + + /* + * Without a certificate callback, the current implementation can't + * figure out if a certificate was actually requested, so "require" is + * useless. + */ + if (strcmp(conn->sslcertmode, "require") == 0) + { + conn->status = CONNECTION_BAD; + libpq_append_conn_error(conn, "%s value \"%s\" is not supported (check OpenSSL version)", + "sslcertmode", conn->sslcertmode); + return false; + } +#endif + } + else + { + conn->sslcertmode = strdup(DefaultSSLCertMode); + if (!conn->sslcertmode) + goto oom_error; + } + /* * validate gssencmode option */ @@ -4238,6 +4290,7 @@ freePGconn(PGconn *conn) explicit_bzero(conn->sslpassword, strlen(conn->sslpassword)); free(conn->sslpassword); } + free(conn->sslcertmode); free(conn->sslrootcert); free(conn->sslcrl); free(conn->sslcrldir); diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c index 6a4431ddfe9..4d1e4009ef1 100644 --- a/src/interfaces/libpq/fe-secure-openssl.c +++ b/src/interfaces/libpq/fe-secure-openssl.c @@ -462,6 +462,34 @@ verify_cb(int ok, X509_STORE_CTX *ctx) return ok; } +#ifdef HAVE_SSL_CTX_SET_CERT_CB +/* + * Certificate selection callback + * + * This callback lets us choose the client certificate we send to the server + * after seeing its CertificateRequest. We only support sending a single + * hard-coded certificate via sslcert, so we don't actually set any certificates + * here; we just use it to record whether or not the server has actually asked + * for one and whether we have one to send. + */ +static int +cert_cb(SSL *ssl, void *arg) +{ + PGconn *conn = arg; + + conn->ssl_cert_requested = true; + + /* Do we have a certificate loaded to send back? */ + if (SSL_get_certificate(ssl)) + conn->ssl_cert_sent = true; + + /* + * Tell OpenSSL that the callback succeeded; we're not required to + * actually make any changes to the SSL handle. + */ + return 1; +} +#endif /* * OpenSSL-specific wrapper around @@ -953,6 +981,11 @@ initialize_SSL(PGconn *conn) SSL_CTX_set_default_passwd_cb_userdata(SSL_context, conn); } +#ifdef HAVE_SSL_CTX_SET_CERT_CB + /* Set up a certificate selection callback. */ + SSL_CTX_set_cert_cb(SSL_context, cert_cb, conn); +#endif + /* Disable old protocol versions */ SSL_CTX_set_options(SSL_context, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3); @@ -1107,7 +1140,12 @@ initialize_SSL(PGconn *conn) else fnbuf[0] = '\0'; - if (fnbuf[0] == '\0') + if (conn->sslcertmode[0] == 'd') /* disable */ + { + /* don't send a client cert even if we have one */ + have_cert = false; + } + else if (fnbuf[0] == '\0') { /* no home directory, proceed without a client cert */ have_cert = false; diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h index 1dc264fe544..10187c31b9a 100644 --- a/src/interfaces/libpq/libpq-int.h +++ b/src/interfaces/libpq/libpq-int.h @@ -384,6 +384,7 @@ struct pg_conn char *sslkey; /* client key filename */ char *sslcert; /* client certificate filename */ char *sslpassword; /* client key file password */ + char *sslcertmode; /* client cert mode (require,allow,disable) */ char *sslrootcert; /* root certificate filename */ char *sslcrl; /* certificate revocation list filename */ char *sslcrldir; /* certificate revocation list directory name */ @@ -527,6 +528,8 @@ struct pg_conn /* SSL structures */ bool ssl_in_use; + bool ssl_cert_requested; /* Did the server ask us for a cert? */ + bool ssl_cert_sent; /* Did we send one in reply? */ #ifdef USE_SSL bool allow_ssl_try; /* Allowed to try SSL negotiation */ diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl index 3094e27af3a..dc43b8f81aa 100644 --- a/src/test/ssl/t/001_ssltests.pl +++ b/src/test/ssl/t/001_ssltests.pl @@ -42,6 +42,10 @@ my $SERVERHOSTADDR = '127.0.0.1'; # This is the pattern to use in pg_hba.conf to match incoming connections. my $SERVERHOSTCIDR = '127.0.0.1/32'; +# Determine whether build supports sslcertmode=require. +my $supports_sslcertmode_require = + check_pg_config("#define HAVE_SSL_CTX_SET_CERT_CB 1"); + # Allocation of base connection string shared among multiple tests. my $common_connstr; @@ -191,6 +195,22 @@ $node->connect_ok( "$common_connstr sslrootcert=ssl/both-cas-2.crt sslmode=verify-ca", "cert root file that contains two certificates, order 2"); +# sslcertmode=allow and disable should both work without a client certificate. +$node->connect_ok( + "$common_connstr sslrootcert=ssl/root+server_ca.crt sslmode=require sslcertmode=disable", + "connect with sslcertmode=disable"); +$node->connect_ok( + "$common_connstr sslrootcert=ssl/root+server_ca.crt sslmode=require sslcertmode=allow", + "connect with sslcertmode=allow"); + +# sslcertmode=require, however, should fail. +$node->connect_fails( + "$common_connstr sslrootcert=ssl/root+server_ca.crt sslmode=require sslcertmode=require", + "connect with sslcertmode=require fails without a client certificate", + expected_stderr => $supports_sslcertmode_require + ? qr/server accepted connection without a valid SSL certificate/ + : qr/sslcertmode value "require" is not supported/); + # CRL tests # Invalid CRL filename is the same as no CRL, succeeds @@ -538,6 +558,28 @@ $node->connect_ok( "certificate authorization succeeds with correct client cert in encrypted DER format" ); +# correct client cert with sslcertmode=allow or require +if ($supports_sslcertmode_require) +{ + $node->connect_ok( + "$common_connstr user=ssltestuser sslcertmode=require sslcert=ssl/client.crt " + . sslkey('client.key'), + "certificate authorization succeeds with correct client cert and sslcertmode=require" + ); +} +$node->connect_ok( + "$common_connstr user=ssltestuser sslcertmode=allow sslcert=ssl/client.crt " + . sslkey('client.key'), + "certificate authorization succeeds with correct client cert and sslcertmode=allow" +); + +# client cert is not sent if sslcertmode=disable. +$node->connect_fails( + "$common_connstr user=ssltestuser sslcertmode=disable sslcert=ssl/client.crt " + . sslkey('client.key'), + "certificate authorization fails with correct client cert and sslcertmode=disable", + expected_stderr => qr/connection requires a valid client certificate/); + # correct client cert in encrypted PEM with wrong password $node->connect_fails( "$common_connstr user=ssltestuser sslcert=ssl/client.crt " diff --git a/src/test/ssl/t/003_sslinfo.pl b/src/test/ssl/t/003_sslinfo.pl index 3f498fff704..c073625213e 100644 --- a/src/test/ssl/t/003_sslinfo.pl +++ b/src/test/ssl/t/003_sslinfo.pl @@ -43,6 +43,10 @@ my $SERVERHOSTADDR = '127.0.0.1'; # This is the pattern to use in pg_hba.conf to match incoming connections. my $SERVERHOSTCIDR = '127.0.0.1/32'; +# Determine whether build supports sslcertmode=require. +my $supports_sslcertmode_require = + check_pg_config("#define HAVE_SSL_CTX_SET_CERT_CB 1"); + # Allocation of base connection string shared among multiple tests. my $common_connstr; @@ -166,4 +170,24 @@ $result = $node->safe_psql( connstr => $common_connstr); is($result, 'CA:FALSE|t', 'extract extension from cert'); +# Sanity tests for sslcertmode, using ssl_client_cert_present() +my @cases = ( + { opts => "sslcertmode=allow", present => 't' }, + { opts => "sslcertmode=allow sslcert=invalid", present => 'f' }, + { opts => "sslcertmode=disable", present => 'f' },); +if ($supports_sslcertmode_require) +{ + push(@cases, { opts => "sslcertmode=require", present => 't' }); +} + +foreach my $c (@cases) +{ + $result = $node->safe_psql( + "trustdb", + "SELECT ssl_client_cert_present();", + connstr => "$common_connstr dbname=trustdb $c->{'opts'}"); + is($result, $c->{'present'}, + "ssl_client_cert_present() for $c->{'opts'}"); +} + done_testing(); diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm index b59953e5b59..153be7be11c 100644 --- a/src/tools/msvc/Solution.pm +++ b/src/tools/msvc/Solution.pm @@ -327,6 +327,7 @@ sub GenerateFiles HAVE_SETPROCTITLE_FAST => undef, HAVE_SOCKLEN_T => 1, HAVE_SPINLOCKS => 1, + HAVE_SSL_CTX_SET_CERT_CB => undef, HAVE_STDBOOL_H => 1, HAVE_STDINT_H => 1, HAVE_STDLIB_H => 1, @@ -506,6 +507,14 @@ sub GenerateFiles $define{HAVE_HMAC_CTX_NEW} = 1; $define{HAVE_OPENSSL_INIT_SSL} = 1; } + + # Symbols needed with OpenSSL 1.0.2 and above. + if ( ($digit1 >= '3' && $digit2 >= '0' && $digit3 >= '0') + || ($digit1 >= '1' && $digit2 >= '1' && $digit3 >= '0') + || ($digit1 >= '1' && $digit2 >= '0' && $digit3 >= '2')) + { + $define{HAVE_SSL_CTX_SET_CERT_CB} = 1; + } } $self->GenerateConfigHeader('src/include/pg_config.h', \%define, 1);