add patch to skip body inspections

Author: thekief

README.md

@@ -45,7 +45,7 @@ Further information about nginx third-party add-ons support are available [here]
 # Usage
 
 ModSecurity for nginx extends your nginx configuration directives.
-It adds four new directives and they are:
+It adds six new directives and they are:
 
 modsecurity
 -----------
@@ -191,6 +191,60 @@ As an open source project we invite (and encourage) anyone from the community to
 functionality, bug fixes, bug reports, beginners user support, and anything else that you
 are willing to help with. Thank you.
 
+modsecurity_skip_req_body_filter
+-----------------
+**syntax:** *modsecurity_skip_req_body_filter on | off*
+
+**context:** *http, server, location*
+
+**default:** *off*
+
+Allows to skip the caching of the request body and subsequently its inspection.
+Useful in cases, where `SecRequestBodyAccess` or `ctl:requestBodyAccess` is set, due to, e.g. encrypted data, as the caching causes an unneeded memory overhead.
+
+
+```nginx
+server {
+    modsecurity on;
+    modsecurity_rules_file /etc/my_modsecurity_rules.conf;
+
+    location / {
+        root /var/www/html;
+    }
+
+    location = /special/unchecked/path {
+        # skip the inspection of the request body
+        modsecurity_skip_req_body_filter on;
+    }
+}
+```
+
+modsecurity_skip_resp_body_filter
+-----------------
+**syntax:** *modsecurity_skip_resp_body_filter on | off*
+
+**context:** *http, server, location*
+
+**default:** *off*
+
+Allows to skip the caching of the request body and subsequently its inspection.
+Useful in cases, where `SecResponseBodyAccess` is set, due to, e.g. encrypted data, as the caching causes an unneeded memory overhead.
+
+```nginx
+server {
+    modsecurity on;
+    modsecurity_rules_file /etc/my_modsecurity_rules.conf;
+
+    location / {
+        root /var/www/html;
+    }
+
+    location = /special/unchecked/path {
+        # skip the inspection of the response body
+        modsecurity_skip_resp_body_filter on;
+    }
+}
+```
 
 ## Providing Patches
 

src/ngx_http_modsecurity_access.c

@@ -56,6 +56,11 @@ ngx_http_modsecurity_access_handler(ngx_http_request_t *r)
         return NGX_DECLINED;
     }
 
+    if(mcf->skip_req_body_filter == 1) {
+        dd("Skipping request body filter");
+        return NGX_DECLINED;
+    }
+
     /*
     if (r->method != NGX_HTTP_GET &&
         r->method != NGX_HTTP_POST && r->method != NGX_HTTP_HEAD) {

src/ngx_http_modsecurity_body_filter.c

@@ -39,8 +39,8 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
 {
     ngx_chain_t *chain = in;
     ngx_http_modsecurity_ctx_t *ctx = NULL;
+    ngx_http_modsecurity_conf_t *mcf = NULL;
 #if defined(MODSECURITY_SANITY_CHECKS) && (MODSECURITY_SANITY_CHECKS)
-    ngx_http_modsecurity_conf_t *mcf;
     ngx_list_part_t *part = &r->headers_out.headers.part;
     ngx_table_elt_t *data = part->elts;
     ngx_uint_t i = 0;
@@ -50,7 +50,19 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
         return ngx_http_next_body_filter(r, in);
     }
 
-    ctx = ngx_http_modsecurity_get_module_ctx(r);
+    mcf = ngx_http_get_module_loc_conf(r, ngx_http_modsecurity_module);
+
+    if (mcf == NULL){
+        dd("failed to get configuration");
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    if (mcf->skip_resp_body_filter) {
+        dd("Skipping response body filter");
+        return ngx_http_next_body_filter(r, in);
+    }
+
+    ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
 
     dd("body filter, recovering ctx: %p", ctx);
 
@@ -63,8 +75,7 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
     }
 
 #if defined(MODSECURITY_SANITY_CHECKS) && (MODSECURITY_SANITY_CHECKS)
-    mcf = ngx_http_get_module_loc_conf(r, ngx_http_modsecurity_module);
-    if (mcf != NULL && mcf->sanity_checks_enabled != NGX_CONF_UNSET)
+    if (mcf->sanity_checks_enabled != NGX_CONF_UNSET)
     {
 #if 0
         dd("dumping stored ctx headers");

src/ngx_http_modsecurity_common.h

@@ -124,6 +124,8 @@ typedef struct {
 #endif
 
     ngx_http_complex_value_t  *transaction_id;
+    ngx_flag_t                 skip_req_body_filter;
+    ngx_flag_t                 skip_resp_body_filter;
 } ngx_http_modsecurity_conf_t;
 
 

src/ngx_http_modsecurity_module.c

@@ -529,6 +529,22 @@ static ngx_command_t ngx_http_modsecurity_commands[] =  {
     offsetof(ngx_http_modsecurity_conf_t, use_error_log),
     NULL
   },
+  {
+    ngx_string("modsecurity_skip_req_body_filter"),
+    NGX_HTTP_LOC_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_MAIN_CONF|NGX_CONF_FLAG,
+    ngx_conf_set_flag_slot,
+    NGX_HTTP_LOC_CONF_OFFSET,
+    offsetof(ngx_http_modsecurity_conf_t, skip_req_body_filter),
+    NULL
+  },
+  {
+    ngx_string("modsecurity_skip_resp_body_filter"),
+    NGX_HTTP_LOC_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_MAIN_CONF|NGX_CONF_FLAG,
+    ngx_conf_set_flag_slot,
+    NGX_HTTP_LOC_CONF_OFFSET,
+    offsetof(ngx_http_modsecurity_conf_t, skip_resp_body_filter),
+    NULL
+  },
   ngx_null_command
 };