[nginx] SSL: passwords support for dynamic certificate loading.

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/180df83473a4
branches:  
changeset: 7463:180df83473a4
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Mon Feb 25 16:42:23 2019 +0300
description:
SSL: passwords support for dynamic certificate loading.

Passwords have to be copied to the configuration pool to be used
at runtime.  Also, to prevent blocking on stdin (with "daemon off;")
an empty password list is provided.

To make things simpler, password handling was modified to allow
an empty array (with 0 elements and elts set to NULL) as an equivalent
of an array with 1 empty password.

diffstat:

 src/event/ngx_event_openssl.c          |  69 +++++++++++++++++++++++++++++++++-
 src/event/ngx_event_openssl.h          |   2 +
 src/http/modules/ngx_http_ssl_module.c |   5 ++
 src/http/ngx_http_request.c            |   3 +-
 4 files changed, 77 insertions(+), 2 deletions(-)

diffs (133 lines):

diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -771,7 +771,7 @@ ngx_ssl_load_certificate_key(ngx_pool_t 
             break;
         }
 
-        if (--tries) {
+        if (tries-- > 1) {
             ERR_clear_error();
             (void) BIO_reset(bio);
             pwd++;
@@ -800,6 +800,10 @@ ngx_ssl_password_callback(char *buf, int
         return 0;
     }
 
+    if (pwd == NULL) {
+        return 0;
+    }
+
     if (pwd->len > (size_t) size) {
         ngx_log_error(NGX_LOG_ERR, ngx_cycle->log, 0,
                       "password is truncated to %d bytes", size);
@@ -1215,6 +1219,69 @@ cleanup:
 }
 
 
+ngx_array_t *
+ngx_ssl_preserve_passwords(ngx_conf_t *cf, ngx_array_t *passwords)
+{
+    ngx_str_t           *opwd, *pwd;
+    ngx_uint_t           i;
+    ngx_array_t         *pwds;
+    ngx_pool_cleanup_t  *cln;
+    static ngx_array_t   empty_passwords;
+
+    if (passwords == NULL) {
+
+        /*
+         * If there are no passwords, an empty array is used
+         * to make sure OpenSSL's default password callback
+         * won't block on reading from stdin.
+         */
+
+        return &empty_passwords;
+    }
+
+    /*
+     * Passwords are normally allocated from the temporary pool
+     * and cleared after parsing configuration.  To be used at
+     * runtime they have to be copied to the configuration pool.
+     */
+
+    pwds = ngx_array_create(cf->pool, passwords->nelts, sizeof(ngx_str_t));
+    if (pwds == NULL) {
+        return NULL;
+    }
+
+    cln = ngx_pool_cleanup_add(cf->pool, 0);
+    if (cln == NULL) {
+        return NULL;
+    }
+
+    cln->handler = ngx_ssl_passwords_cleanup;
+    cln->data = pwds;
+
+    opwd = passwords->elts;
+
+    for (i = 0; i < passwords->nelts; i++) {
+
+        pwd = ngx_array_push(pwds);
+        if (pwd == NULL) {
+            return NULL;
+        }
+
+        pwd->len = opwd[i].len;
+        pwd->data = ngx_pnalloc(cf->pool, pwd->len);
+
+        if (pwd->data == NULL) {
+            pwds->nelts--;
+            return NULL;
+        }
+
+        ngx_memcpy(pwd->data, opwd[i].data, opwd[i].len);
+    }
+
+    return pwds;
+}
+
+
 static void
 ngx_ssl_passwords_cleanup(void *data)
 {
diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h
--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -183,6 +183,8 @@ ngx_int_t ngx_ssl_stapling_resolver(ngx_
 RSA *ngx_ssl_rsa512_key_callback(ngx_ssl_conn_t *ssl_conn, int is_export,
     int key_length);
 ngx_array_t *ngx_ssl_read_password_file(ngx_conf_t *cf, ngx_str_t *file);
+ngx_array_t *ngx_ssl_preserve_passwords(ngx_conf_t *cf,
+    ngx_array_t *passwords);
 ngx_int_t ngx_ssl_dhparam(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_str_t *file);
 ngx_int_t ngx_ssl_ecdh_curve(ngx_conf_t *cf, ngx_ssl_t *ssl, ngx_str_t *name);
 ngx_int_t ngx_ssl_early_data(ngx_conf_t *cf, ngx_ssl_t *ssl,
diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c
--- a/src/http/modules/ngx_http_ssl_module.c
+++ b/src/http/modules/ngx_http_ssl_module.c
@@ -935,6 +935,11 @@ found:
         }
     }
 
+    conf->passwords = ngx_ssl_preserve_passwords(cf, conf->passwords);
+    if (conf->passwords == NULL) {
+        return NGX_ERROR;
+    }
+
     return NGX_OK;
 }
 
diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -995,7 +995,8 @@ ngx_http_ssl_certificate(ngx_ssl_conn_t 
         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                        "ssl key: \"%s\"", key.data);
 
-        if (ngx_ssl_connection_certificate(c, r->pool, &cert, &key, NULL)
+        if (ngx_ssl_connection_certificate(c, r->pool, &cert, &key,
+                                           sscf->passwords)
             != NGX_OK)
         {
             goto failed;