From bcd02edd8032ba3a3de40cbc35dda3529da00a7c Mon Sep 17 00:00:00 2001
From: zotlabs <mike@macgirvin.com>
Date: Wed, 15 Mar 2017 15:53:03 -0700
Subject: ensure z_input_filter is called exactly once, since we now depend on
 the number of htmlspecialchars operations for markdown content. Also ensure
 that the content is escaped the correct number of times on imported items.

---
 include/items.php | 68 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 46 insertions(+), 22 deletions(-)

(limited to 'include/items.php')

diff --git a/include/items.php b/include/items.php
index c978805cd..ace8b2fb2 100755
--- a/include/items.php
+++ b/include/items.php
@@ -528,11 +528,6 @@ function get_item_elements($x,$allow_code = false) {
 
 	$arr = array();
 
-	if($allow_code)
-		$arr['body'] = $x['body'];
-	else
-		$arr['body'] = (($x['body']) ? htmlspecialchars($x['body'],ENT_COMPAT,'UTF-8',false) : '');
-
 	$key = get_config('system','pubkey');
 
 	$maxlen = get_max_import_size();
@@ -640,7 +635,17 @@ function get_item_elements($x,$allow_code = false) {
 			return array();
 	}
 
+	// Check signature on the body text received. 
+	// This presents an issue that we aren't verifying the text that is actually displayed
+	// on this site. We are however verifying the received text was exactly as received.
+	// We have every right to strip content that poses a security risk. You are welcome to
+	// create a plugin to verify the content after filtering if this offends you.  
+
 	if($arr['sig']) {
+
+		// check the supplied signature against the supplied content.
+		// Note that we will purify the content which could change it.
+
 		$r = q("select xchan_pubkey from xchan where xchan_hash = '%s' limit 1",
 			dbesc($arr['author_xchan'])
 		);
@@ -650,6 +655,14 @@ function get_item_elements($x,$allow_code = false) {
 			logger('get_item_elements: message verification failed.');
 	}
 
+	// if the input is markdown, remove one level of html escaping.
+	// It will be re-applied in item_store() and/or item_store_update().
+	// Do this after signature checking as the original signature
+	// was generated on the escaped content.
+
+	if($arr['mimetype'] === 'text/markdown')
+		$arr['body'] = \Zotlabs\Lib\MarkdownSoap::unescape($arr['body']);
+
 	if(array_key_exists('revision',$x)) {
 
 		// extended export encoding
@@ -1475,14 +1488,20 @@ function item_store($arr, $allow_exec = false, $deliver = true) {
 
 	$arr['lang'] = detect_language($arr['body']);
 	// apply the input filter here
-	$arr['body'] = trim(z_input_filter($arr['body'],$arr['mimetype'],$allow_exec));
-
-	if(local_channel() && (local_channel() == $arr['uid'])) {
-		if(! $arr['sig']) {
-			$channel = App::get_channel();
-			if($channel['channel_hash'] === $arr['author_xchan']) {
-				$arr['sig'] = base64url_encode(rsa_sign($arr['body'],$channel['channel_prvkey']));
-				$arr['item_verified'] = 1;
+
+	if(array_key_exists('input_filtered_signed',$arr)) {
+		unset($arr['input_filtered_signed']);
+	}
+	else {
+		$arr['body'] = trim(z_input_filter($arr['body'],$arr['mimetype'],$allow_exec));
+
+		if(local_channel() && (local_channel() == $arr['uid'])) {
+			if(! $arr['sig']) {
+				$channel = App::get_channel();
+				if($channel['channel_hash'] === $arr['author_xchan']) {
+					$arr['sig'] = base64url_encode(rsa_sign($arr['body'],$channel['channel_prvkey']));
+					$arr['item_verified'] = 1;
+				}
 			}
 		}
 	}
@@ -1896,17 +1915,22 @@ function item_store_update($arr,$allow_exec = false, $deliver = true) {
 		return $ret;
 	}
 
-
 	$arr['lang'] = detect_language($arr['body']);
 
-	// apply the input filter here
-	$arr['body'] = trim($arr['body'],$arr['mimetype'],$allow_exec);
-
-	if(local_channel() && (local_channel() == $arr['uid']) && (! $arr['sig'])) {
-		$channel = App::get_channel();
-		if($channel['channel_hash'] === $arr['author_xchan']) {
-			$arr['sig'] = base64url_encode(rsa_sign($arr['body'],$channel['channel_prvkey']));
-			$arr['item_verified'] = 1;
+	if(array_key_exists('input_filtered_signed',$arr)) {
+		unset($arr['input_filtered_signed']);
+	}
+	else {
+		$arr['body'] = trim(z_input_filter($arr['body'],$arr['mimetype'],$allow_exec));
+
+		if(local_channel() && (local_channel() == $arr['uid'])) {
+			if(! $arr['sig']) {
+				$channel = App::get_channel();
+				if($channel['channel_hash'] === $arr['author_xchan']) {
+					$arr['sig'] = base64url_encode(rsa_sign($arr['body'],$channel['channel_prvkey']));
+					$arr['item_verified'] = 1;
+				}
+			}
 		}
 	}
 
-- 
cgit v1.2.3