Backport of:

From a962ba73047b5478d702c8ad09fd1a167e1d3736 Mon Sep 17 00:00:00 2001
From: Yann Ylavic <ylavic@apache.org>
Date: Tue, 14 Dec 2021 15:35:56 +0000
Subject: [PATCH] Merge r1895914, r1895921 from trunk:

  *) http: Enforce that fully qualified uri-paths not to be forward-proxied
     have an http(s) scheme, and that the ones to be forward proxied have a
     hostname, per HTTP specifications.
     trunk patch: http://svn.apache.org/r1895914
                  http://svn.apache.org/r1895921
     2.4.x patch: https://patch-diff.githubusercontent.com/raw/apache/httpd/pull/286.patch
     backport PR: https://github.com/apache/httpd/pull/286
     +1: ylavic, minfrin, gbechis


mod_proxy: Detect unix: scheme syntax errors at load time.

* modules/proxy/mod_proxy.c(add_pass, add_member, set_proxy_param,
                            proxysection):
  Check return value of ap_proxy_de_socketfy().

* modules/proxy/proxy_util.c(ap_proxy_get_worker_ex):
  Check return value of ap_proxy_de_socketfy().



http: Enforce that fully qualified uri-paths not to be forward-proxied
      have an http(s) scheme, and that the ones to be forward proxied have a
      hostname, per HTTP specifications.

The early checks avoid failing the request later on and thus save cycles
for those invalid cases.


Submitted by: ylavic
Reviewed by: ylavic, minfrin, gbechis
Closes #286


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1895955 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES                     |  4 ++++
 include/ap_mmn.h            |  3 ++-
 include/http_protocol.h     |  7 ++++++
 modules/http/http_request.c |  2 +-
 modules/http2/h2_request.c  |  2 +-
 modules/proxy/mod_proxy.c   | 44 ++++++++++++++++++++++++++-----------
 modules/proxy/proxy_util.c  |  3 +++
 server/protocol.c           | 23 ++++++++++++++++++-
 8 files changed, 71 insertions(+), 17 deletions(-)

#diff --git a/CHANGES b/CHANGES
#index 910a689445c..12ad612d5cb 100644
#--- a/CHANGES
#+++ b/CHANGES
#@@ -1,6 +1,10 @@
#                                                          -*- coding: utf-8 -*-
# Changes with Apache 2.4.52
# 
#+  *) http: Enforce that fully qualified uri-paths not to be forward-proxied
#+     have an http(s) scheme, and that the ones to be forward proxied have a
#+     hostname, per HTTP specifications.  [Ruediger Pluem, Yann Ylavic]
#+
#   *) OpenSSL autoconf detection improvement: pick up openssl.pc in the
#      specified openssl path. [Joe Orton]
# 
#diff --git a/include/ap_mmn.h b/include/ap_mmn.h
#index fe24261ee87..90ff1a86a6f 100644
#--- a/include/ap_mmn.h
#+++ b/include/ap_mmn.h
#@@ -586,6 +586,7 @@
#  *                           dav_find_attr().
#  * 20120211.120 (2.4.51-dev) Add dav_liveprop_elem structure and
#  *                           dav_get_liveprop_element().
#+ * 20120211.121 (2.4.51-dev) Add ap_post_read_request()
#  * 
#  */
# 
#@@ -594,7 +595,7 @@
# #ifndef MODULE_MAGIC_NUMBER_MAJOR
# #define MODULE_MAGIC_NUMBER_MAJOR 20120211
# #endif
#-#define MODULE_MAGIC_NUMBER_MINOR 120                 /* 0...n */
#+#define MODULE_MAGIC_NUMBER_MINOR 121                 /* 0...n */
# 
# /**
#  * Determine if the server's current MODULE_MAGIC_NUMBER is at least a
--- a/include/http_protocol.h
+++ b/include/http_protocol.h
@@ -96,6 +96,13 @@ AP_DECLARE(void) ap_get_mime_headers(req
 AP_DECLARE(void) ap_get_mime_headers_core(request_rec *r,
                                           apr_bucket_brigade *bb);
 
+/**
+ * Run post_read_request hook and validate.
+ * @param r The current request
+ * @return OK or HTTP_...
+ */
+AP_DECLARE(int) ap_post_read_request(request_rec *r);
+
 /* Finish up stuff after a request */
 
 /**
--- a/modules/http/http_request.c
+++ b/modules/http/http_request.c
@@ -655,7 +655,7 @@ static request_rec *internal_internal_re
      * to do their thing on internal redirects as well.  Perhaps this is a
      * misnamed function.
      */
-    if ((access_status = ap_run_post_read_request(new))) {
+    if ((access_status = ap_post_read_request(new))) {
         ap_die(access_status, new);
         return NULL;
     }
--- a/modules/http2/h2_request.c
+++ b/modules/http2/h2_request.c
@@ -262,7 +262,7 @@ request_rec *h2_request_create_rec(const
     ap_add_input_filter_handle(ap_http_input_filter_handle,
                                NULL, r, r->connection);
     
-    if ((access_status = ap_run_post_read_request(r))) {
+    if ((access_status = ap_post_read_request(r))) {
         /* Request check post hooks failed. An example of this would be a
          * request for a vhost where h2 is disabled --> 421.
          */
--- a/modules/proxy/mod_proxy.c
+++ b/modules/proxy/mod_proxy.c
@@ -556,13 +556,13 @@ static int proxy_detect(request_rec *r)
 
     /* Ick... msvc (perhaps others) promotes ternary short results to int */
 
-    if (conf->req && r->parsed_uri.scheme) {
+    if (conf->req && r->parsed_uri.scheme && r->parsed_uri.hostname) {
         /* but it might be something vhosted */
-        if (!(r->parsed_uri.hostname
-              && !strcasecmp(r->parsed_uri.scheme, ap_http_scheme(r))
-              && ap_matches_request_vhost(r, r->parsed_uri.hostname,
-                                          (apr_port_t)(r->parsed_uri.port_str ? r->parsed_uri.port
-                                                       : ap_default_port(r))))) {
+        if (strcasecmp(r->parsed_uri.scheme, ap_http_scheme(r)) != 0
+            || !ap_matches_request_vhost(r, r->parsed_uri.hostname,
+                                         (apr_port_t)(r->parsed_uri.port_str
+                                                      ? r->parsed_uri.port
+                                                      : ap_default_port(r)))) {
             r->proxyreq = PROXYREQ_PROXY;
             r->uri = r->unparsed_uri;
             r->filename = apr_pstrcat(r->pool, "proxy:", r->uri, NULL);
@@ -1609,6 +1609,7 @@ static const char *
     struct proxy_alias *new;
     char *f = cmd->path;
     char *r = NULL;
+    const char *real;
     char *word;
     apr_table_t *params = apr_table_make(cmd->pool, 5);
     const apr_array_header_t *arr;
@@ -1674,6 +1675,10 @@ static const char *
     if (r == NULL) {
         return "ProxyPass|ProxyPassMatch needs a path when not defined in a location";
     }
+    if (!(real = ap_proxy_de_socketfy(cmd->temp_pool, r))) {
+        return "ProxyPass|ProxyPassMatch uses an invalid \"unix:\" URL";
+    }
+
 
     /* if per directory, save away the single alias */
     if (cmd->path) {
@@ -1690,7 +1695,7 @@ static const char *
     }
 
     new->fake = apr_pstrdup(cmd->pool, f);
-    new->real = apr_pstrdup(cmd->pool, ap_proxy_de_socketfy(cmd->pool, r));
+    new->real = apr_pstrdup(cmd->pool, real);
     new->flags = flags;
     if (use_regex) {
         new->regex = ap_pregcomp(cmd->pool, f, AP_REG_EXTENDED);
@@ -2167,6 +2172,7 @@ static const char *add_member(cmd_parms
     proxy_worker *worker;
     char *path = cmd->path;
     char *name = NULL;
+    const char *real;
     char *word;
     apr_table_t *params = apr_table_make(cmd->pool, 5);
     const apr_array_header_t *arr;
@@ -2207,6 +2213,9 @@ static const char *add_member(cmd_parms
         return "BalancerMember must define balancer name when outside <Proxy > section";
     if (!name)
         return "BalancerMember must define remote proxy server";
+    if (!(real = ap_proxy_de_socketfy(cmd->temp_pool, name))) {
+        return "BalancerMember uses an invalid \"unix:\" URL";
+    }
 
     ap_str_tolower(path);   /* lowercase scheme://hostname */
 
@@ -2219,7 +2228,7 @@ static const char *add_member(cmd_parms
     }
 
     /* Try to find existing worker */
-    worker = ap_proxy_get_worker(cmd->temp_pool, balancer, conf, ap_proxy_de_socketfy(cmd->temp_pool, name));
+    worker = ap_proxy_get_worker(cmd->temp_pool, balancer, conf, real);
     if (!worker) {
         ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, cmd->server, APLOGNO(01147)
                      "Defining worker '%s' for balancer '%s'",
@@ -2305,7 +2314,13 @@ static const char *
         }
     }
     else {
-        worker = ap_proxy_get_worker(cmd->temp_pool, NULL, conf, ap_proxy_de_socketfy(cmd->temp_pool, name));
+        const char *real;
+
+        if (!(real = ap_proxy_de_socketfy(cmd->temp_pool, name))) {
+            return "ProxySet uses an invalid \"unix:\" URL";
+        }
+
+        worker = ap_proxy_get_worker(cmd->temp_pool, NULL, conf, real);
         if (!worker) {
             if (in_proxy_section) {
                 err = ap_proxy_define_worker(cmd->pool, &worker, NULL,
@@ -2444,8 +2459,14 @@ static const char *proxysection(cmd_parm
             }
         }
         else {
+            const char *real;
+
+            if (!(real = ap_proxy_de_socketfy(cmd->temp_pool, conf->p))) {
+                return "<Proxy/ProxyMatch > uses an invalid \"unix:\" URL";
+            }
+
             worker = ap_proxy_get_worker(cmd->temp_pool, NULL, sconf,
-                                         ap_proxy_de_socketfy(cmd->temp_pool, (char*)conf->p));
+                                         real);
             if (!worker) {
                 err = ap_proxy_define_worker(cmd->pool, &worker, NULL,
                                           sconf, conf->p, 0);
--- a/modules/proxy/proxy_util.c
+++ b/modules/proxy/proxy_util.c
@@ -1524,6 +1524,9 @@ PROXY_DECLARE(proxy_worker *) ap_proxy_g
     }
 
     url = ap_proxy_de_socketfy(p, url);
+    if (!url) {
+        return NULL;
+    }
 
     c = ap_strchr_c(url, ':');
     if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0') {
--- a/server/protocol.c
+++ b/server/protocol.c
@@ -1469,7 +1469,7 @@ request_rec *ap_read_request(conn_rec *c
     /* we may have switched to another server */
     apply_server_config(r);
 
-    if ((access_status = ap_run_post_read_request(r))) {
+    if ((access_status = ap_post_read_request(r))) {
         goto die;
     }
 
@@ -1524,6 +1524,27 @@ ignore:
     return NULL;
 }
 
+AP_DECLARE(int) ap_post_read_request(request_rec *r)
+{
+    int status;
+
+    if ((status = ap_run_post_read_request(r))) {
+        return status;
+    }
+
+    /* Enforce http(s) only scheme for non-forward-proxy requests */
+    if (!r->proxyreq
+            && r->parsed_uri.scheme
+            && (ap_cstr_casecmpn(r->parsed_uri.scheme, "http", 4) != 0
+                || (r->parsed_uri.scheme[4] != '\0'
+                    && (apr_tolower(r->parsed_uri.scheme[4]) != 's'
+                        || r->parsed_uri.scheme[5] != '\0')))) {
+        return HTTP_BAD_REQUEST;
+    }
+
+    return OK;
+}
+
 /* if a request with a body creates a subrequest, remove original request's
  * input headers which pertain to the body which has already been read.
  * out-of-line helper function for ap_set_sub_req_protocol.
