make ssl certificate handling much more useful:
- system-wide ca certs are auto-loaded - private certs are accepted even if they are self-signed
This commit is contained in:
Oswald Buddenhagen
parent
06521da30d
commit
262999d092
106
src/drv_imap.c
106
src/drv_imap.c
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@ -66,6 +66,7 @@ typedef struct imap_server_conf {
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unsigned use_sslv3:1;
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unsigned use_tlsv1:1;
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unsigned require_cram:1;
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X509_STORE *cert_store;
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#endif
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} imap_server_conf_t;
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@ -182,15 +183,46 @@ static const char *Flags[] = {
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};
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#if HAVE_LIBSSL
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/* Some of this code is inspired by / lifted from mutt. */
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static int
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compare_certificates( X509 *cert, X509 *peercert,
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unsigned char *peermd, unsigned peermdlen )
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{
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unsigned char md[EVP_MAX_MD_SIZE];
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unsigned mdlen;
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/* Avoid CPU-intensive digest calculation if the certificates are
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* not even remotely equal. */
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if (X509_subject_name_cmp( cert, peercert ) ||
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X509_issuer_name_cmp( cert, peercert ))
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return -1;
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if (!X509_digest( cert, EVP_sha1(), md, &mdlen ) ||
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peermdlen != mdlen || memcmp( peermd, md, mdlen ))
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return -1;
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return 0;
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}
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#if OPENSSL_VERSION_NUMBER >= 0x00904000L
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#define READ_X509_KEY(fp, key) PEM_read_X509( fp, key, 0, 0 )
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#else
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#define READ_X509_KEY(fp, key) PEM_read_X509( fp, key, 0 )
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#endif
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/* this gets called when a certificate is to be verified */
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static int
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verify_cert( SSL *ssl )
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verify_cert( imap_store_t *ctx )
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{
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X509 *cert;
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imap_server_conf_t *srvc = ((imap_store_conf_t *)ctx->gen.conf)->server;
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SSL *ssl = ctx->buf.sock.ssl;
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X509 *cert, *lcert;
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BIO *bio;
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FILE *fp;
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int err;
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unsigned n, i;
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X509_STORE_CTX xsc;
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char buf[256];
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unsigned char md[EVP_MAX_MD_SIZE];
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@ -200,12 +232,58 @@ verify_cert( SSL *ssl )
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return -1;
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}
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err = SSL_get_verify_result( ssl );
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if (err == X509_V_OK)
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return 0;
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while (srvc->cert_file) { // So break works
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if (X509_cmp_current_time( X509_get_notBefore( cert )) >= 0) {
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error( "Server certificate is not yet valid" );
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break;
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}
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if (X509_cmp_current_time( X509_get_notAfter( cert )) <= 0) {
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error( "Server certificate has expired" );
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break;
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}
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if (!X509_digest( cert, EVP_sha1(), md, &n )) {
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error( "*** Unable to calculate digest\n" );
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break;
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}
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if (!(fp = fopen( srvc->cert_file, "rt" ))) {
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error( "Unable to load CertificateFile '%s': %s\n",
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srvc->cert_file, strerror( errno ) );
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return 0;
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}
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for (lcert = 0; READ_X509_KEY( fp, &lcert ); )
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if (!(err = compare_certificates( lcert, cert, md, n )))
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break;
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X509_free( lcert );
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fclose( fp );
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if (!err)
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return 0;
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break;
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}
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if (!srvc->cert_store) {
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if (!(srvc->cert_store = X509_STORE_new())) {
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error( "Error creating certificate store\n" );
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return -1;
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}
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if (!X509_STORE_set_default_paths( srvc->cert_store ))
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warn( "Error while loading default certificate files: %s\n",
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ERR_error_string( ERR_get_error(), 0 ) );
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if (!srvc->cert_file) {
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info( "Note: CertificateFile not defined\n" );
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} else if (!X509_STORE_load_locations( srvc->cert_store, srvc->cert_file, 0 )) {
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error( "Error while loading certificate file '%s': %s\n",
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srvc->cert_file, ERR_error_string( ERR_get_error(), 0 ) );
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return -1;
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}
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}
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X509_STORE_CTX_init( &xsc, srvc->cert_store, cert, 0 );
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err = X509_verify_cert( &xsc ) > 0 ? 0 : X509_STORE_CTX_get_error( &xsc );
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X509_STORE_CTX_cleanup( &xsc );
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if (!err)
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return 0;
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error( "Error, can't verify certificate: %s (%d)\n",
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X509_verify_cert_error_string(err), err );
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X509_verify_cert_error_string( err ), err );
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X509_NAME_oneline( X509_get_subject_name( cert ), buf, sizeof(buf) );
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info( "\nSubject: %s\n", buf );
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@ -221,9 +299,9 @@ verify_cert( SSL *ssl )
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BIO_read( bio, buf, sizeof(buf) - 1 );
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BIO_free( bio );
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info( " to: %s\n", buf );
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if (!X509_digest( cert, EVP_md5(), md, &n ))
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info( "*** Unable to calculate fingerprint\n" );
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else {
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if (!X509_digest( cert, EVP_md5(), md, &n )) {
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error( "*** Unable to calculate fingerprint\n" );
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} else {
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info( "Fingerprint: " );
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for (i = 0; i < n; i += 2)
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info( "%02X%02X ", md[i], md[i + 1] );
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@ -249,14 +327,6 @@ init_ssl_ctx( imap_store_t *ctx )
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method = SSLv23_client_method();
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ctx->SSLContext = SSL_CTX_new( method );
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if (!srvc->cert_file) {
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info( "Note: CertificateFile not defined\n" );
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} else if (!SSL_CTX_load_verify_locations( ctx->SSLContext, srvc->cert_file, NULL )) {
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error( "Error while loading certificate file '%s': %s\n",
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srvc->cert_file, ERR_error_string( ERR_get_error(), 0 ) );
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return -1;
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}
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if (!srvc->use_sslv2)
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options |= SSL_OP_NO_SSLv2;
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if (!srvc->use_sslv3)
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@ -1121,7 +1191,7 @@ start_tls( imap_store_t *ctx )
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}
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/* verify the server certificate */
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if (verify_cert( ctx->buf.sock.ssl ))
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if (verify_cert( ctx ))
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return 1;
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ctx->buf.sock.use_ssl = 1;
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