From 6406e2108db29697501a84015e46296b8d09356d Mon Sep 17 00:00:00 2001
From: Felipe Zimmerle <fcosta@trustwave.com>
Date: Thu, 5 Oct 2017 18:25:52 +0000
Subject: [PATCH] Makes `large stream optimization' optional

---
 apache2/apache2_io.c   |  6 ++++-
 apache2/modsecurity.h  |  3 +++
 apache2/msc_reqbody.c  | 53 ++++++++++++++++++++++++++++++++++++++++--
 apache2/re_operators.c |  9 ++++++-
 configure.ac           | 18 +++++++++++++-
 5 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/apache2/apache2_io.c b/apache2/apache2_io.c
index 9007f9d5..2e7325dc 100644
--- a/apache2/apache2_io.c
+++ b/apache2/apache2_io.c
@@ -192,7 +192,6 @@ apr_status_t read_request_body(modsec_rec *msr, char **error_msg) {
     if (msr->txcfg->debuglog_level >= 4) {
         msr_log(msr, 4, "Input filter: Reading request body.");
     }
-
     if (modsecurity_request_body_start(msr, error_msg) < 0) {
         return -1;
     }
@@ -283,9 +282,14 @@ apr_status_t read_request_body(modsec_rec *msr, char **error_msg) {
             }
 
             if (msr->txcfg->stream_inbody_inspection == 1)   {
+#ifndef MSC_LARGE_STREAM_INPUT
+                msr->stream_input_length+=buflen;
+                modsecurity_request_body_to_stream(msr, buf, buflen, error_msg);
+#else
                 if (modsecurity_request_body_to_stream(msr, buf, buflen, error_msg) < 0) {
                     return -1;
                 }
+#endif
             }
 
             msr->reqbody_length += buflen;
diff --git a/apache2/modsecurity.h b/apache2/modsecurity.h
index 601b5f24..f24bc756 100644
--- a/apache2/modsecurity.h
+++ b/apache2/modsecurity.h
@@ -287,7 +287,10 @@ struct modsec_rec {
     unsigned int         resbody_contains_html;
 
     apr_size_t           stream_input_length;
+#ifdef MSC_LARGE_STREAM_INPUT
     apr_size_t           stream_input_allocated_length;
+#endif
+
     char                *stream_input_data;
     apr_size_t           stream_output_length;
     char                *stream_output_data;
diff --git a/apache2/msc_reqbody.c b/apache2/msc_reqbody.c
index ebf4e516..fc6b380b 100644
--- a/apache2/msc_reqbody.c
+++ b/apache2/msc_reqbody.c
@@ -428,9 +428,59 @@ apr_status_t modsecurity_request_body_store(modsec_rec *msr,
 }
 
 apr_status_t modsecurity_request_body_to_stream(modsec_rec *msr, const char *buffer, int buflen, char **error_msg) {
+#ifndef MSC_LARGE_STREAM_INPUT
+    char *stream_input_body = NULL;
+    char *data = NULL;
+    int first_pkt = 0;
+#else
     apr_size_t allocate_length = 0;
     char* allocated = NULL;
+#endif
 
+#ifndef MSC_LARGE_STREAM_INPUT
+    if(msr->stream_input_data == NULL)  {
+        msr->stream_input_data = (char *)calloc(sizeof(char), msr->stream_input_length + 1);
+        first_pkt = 1;
+    }
+    else    {
+
+        data = (char *)malloc(msr->stream_input_length + 1 - buflen);
+
+        if(data == NULL)
+            return -1;
+
+        memset(data, 0, msr->stream_input_length + 1 - buflen);
+        memcpy(data, msr->stream_input_data, msr->stream_input_length - buflen);
+
+        stream_input_body = (char *)realloc(msr->stream_input_data, msr->stream_input_length + 1);
+
+        msr->stream_input_data = (char *)stream_input_body;
+    }
+
+    if (msr->stream_input_data == NULL) {
+        if(data)    {
+            free(data);
+            data = NULL;
+        }
+        *error_msg = apr_psprintf(msr->mp, "Unable to allocate memory to hold request body on stream. Asked for %" APR_SIZE_T_FMT " bytes.",
+                msr->stream_input_length + 1);
+        return -1;
+    }
+
+    memset(msr->stream_input_data, 0, msr->stream_input_length+1);
+
+    if(first_pkt)   {
+        memcpy(msr->stream_input_data, buffer, msr->stream_input_length);
+    } else {
+        memcpy(msr->stream_input_data, data, msr->stream_input_length - buflen);
+        memcpy(msr->stream_input_data+(msr->stream_input_length - buflen), buffer, buflen);
+    }
+
+    if(data)    {
+        free(data);
+        data = NULL;
+    }
+#else
     if (msr->stream_input_data == NULL)  {
         // Is the request body length known beforehand? (requests that are not Transfer-Encoding: chunked)
         if (msr->request_content_length > 0) {
@@ -458,7 +508,6 @@ apr_status_t modsecurity_request_body_to_stream(modsec_rec *msr, const char *buf
     else {
         // Do we need to expand the space we have previously allocated?
         if ((msr->stream_input_length + buflen) > msr->stream_input_allocated_length) {
-
             // If this becomes a hotspot again, consider increasing by some percent extra each time, for fewer reallocs
             allocate_length = msr->stream_input_length + buflen;
 
@@ -480,10 +529,10 @@ apr_status_t modsecurity_request_body_to_stream(modsec_rec *msr, const char *buf
             }
         }
     }
-
     // Append buffer to msr->stream_input_data
     memcpy(msr->stream_input_data + msr->stream_input_length, buffer, buflen);
     msr->stream_input_length += buflen;
+#endif
 
     return 1;
 }
diff --git a/apache2/re_operators.c b/apache2/re_operators.c
index 05db118f..b6d1c03c 100644
--- a/apache2/re_operators.c
+++ b/apache2/re_operators.c
@@ -634,18 +634,25 @@ nextround:
         free(msr->stream_input_data);
         msr->stream_input_data = NULL;
         msr->stream_input_length = 0;
+#ifdef MSC_LARGE_STREAM_INPUT
         msr->stream_input_allocated_length  = 0;
 
         msr->stream_input_data = (char *)malloc(size);
+#else
+        msr->stream_input_data = (char *)malloc(size+1);
+#endif
 
         if(msr->stream_input_data == NULL)  {
             return -1;
         }
 
         msr->stream_input_length = size;
+#ifdef MSC_LARGE_STREAM_INPUT
         msr->stream_input_allocated_length = size;
         memset(msr->stream_input_data, 0x0, size);
-
+#else
+        memset(msr->stream_input_data, 0x0, size+1);
+#endif
         msr->if_stream_changed = 1;
 
         memcpy(msr->stream_input_data, data, size);
diff --git a/configure.ac b/configure.ac
index e3a3595f..01d2fb4b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -690,6 +690,22 @@ AC_ARG_ENABLE(modsec-api,
   modsec_api=
 ])
 
+# MSC_LARGE_STREAM_INPUT
+AC_ARG_ENABLE(large-stream-input,
+              AS_HELP_STRING([--enable-large-stream-input],
+                             [Enable optimization for large stream input]),
+[
+  if test "$enableval" == "yes"; then
+    large_stream_input="-DMSC_LARGE_STREAM_INPUT"
+    MODSEC_EXTRA_CFLAGS="$MODSEC_EXTRA_CFLAGS $large_stream_input"
+  else
+    large_stream_input=
+  fi
+],
+[
+  large_stream_input=
+])
+
 # Find apxs
 AC_MSG_NOTICE(looking for Apache module support via DSO through APXS)
 AC_ARG_WITH(apxs,
@@ -812,7 +828,7 @@ else
   fi
 fi
 
-MODSEC_EXTRA_CFLAGS="$pcre_study $pcre_match_limit $pcre_match_limit_recursion $pcre_jit $request_early $htaccess_config $lua_cache $debug_conf $debug_cache $debug_acmp $debug_mem $perf_meas $modsec_api $cpu_type $unique_id $log_filename $log_server $log_collection_delete_problem $log_dechunk $log_stopwatch $log_handler $log_server_context $collection_global_lock"
+MODSEC_EXTRA_CFLAGS="$pcre_study $pcre_match_limit $pcre_match_limit_recursion $pcre_jit $request_early $htaccess_config $lua_cache $debug_conf $debug_cache $debug_acmp $debug_mem $perf_meas $modsec_api $cpu_type $unique_id $log_filename $log_server $log_collection_delete_problem $log_dechunk $log_stopwatch $log_handler $log_server_context $collection_global_lock $large_stream_input"
 
 APXS_WRAPPER=build/apxs-wrapper
 APXS_EXTRA_CFLAGS=""