From: YAMADA Yasuharu <yasuharu.yamada@access-company.com>
Date: Wed, 10 Apr 2013 22:17:15 +0000 (+0200)
Subject: cookie: fix tailmatching to prevent cross-domain leakage
X-Git-Tag: curl-7_30_0~2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2eb8dcf26cb37f09cffe26909a646e702dbcab66;p=thirdparty%2Fcurl.git

cookie: fix tailmatching to prevent cross-domain leakage

Cookies set for 'example.com' could accidentaly also be sent by libcurl
to the 'bexample.com' (ie with a prefix to the first domain name).

This is a security vulnerabilty, CVE-2013-1944.

Bug: http://curl.haxx.se/docs/adv_20130412.html
---

diff --git a/lib/cookie.c b/lib/cookie.c
index 4b9ec0bdd9..a67204e6e2 100644
--- a/lib/cookie.c
+++ b/lib/cookie.c
@@ -118,15 +118,29 @@ static void freecookie(struct Cookie *co)
   free(co);
 }
 
-static bool tailmatch(const char *little, const char *bigone)
+static bool tailmatch(const char *cooke_domain, const char *hostname)
 {
-  size_t littlelen = strlen(little);
-  size_t biglen = strlen(bigone);
+  size_t cookie_domain_len = strlen(cooke_domain);
+  size_t hostname_len = strlen(hostname);
 
-  if(littlelen > biglen)
+  if(hostname_len < cookie_domain_len)
     return FALSE;
 
-  return Curl_raw_equal(little, bigone+biglen-littlelen) ? TRUE : FALSE;
+  if(!Curl_raw_equal(cooke_domain, hostname+hostname_len-cookie_domain_len))
+    return FALSE;
+
+  /* A lead char of cookie_domain is not '.'.
+     RFC6265 4.1.2.3. The Domain Attribute says:
+       For example, if the value of the Domain attribute is
+       "example.com", the user agent will include the cookie in the Cookie
+       header when making HTTP requests to example.com, www.example.com, and
+       www.corp.example.com.
+   */
+  if(hostname_len == cookie_domain_len)
+    return TRUE;
+  if('.' == *(hostname + hostname_len - cookie_domain_len - 1))
+    return TRUE;
+  return FALSE;
 }
 
 /*