From 8fc4b4792919c627183f4ddb6dc256aae49eb738 Mon Sep 17 00:00:00 2001
From: Hiroshi SHIBATA <hsbt@ruby-lang.org>
Date: Tue, 22 Nov 2022 13:48:18 +0900
Subject: [PATCH] Fix CVE-2021-33621 HTTP response splitting in CGI.

Backported from upstream Ruby, commit:
https://github.com/ruby/ruby/commit/7cf697179dab52b0d024543304f4d3ab5fa5e847

Test "CGICookieTest#test_cgi_cookie_new_with_domain" was adjusted to
deal with Ruby 2.5 not allowing String with double splat operator.

==== Original commit message
Merge CGI-0.1.0.2
---
 lib/cgi/cookie.rb           | 51 ++++++++++++++++-------
 lib/cgi/core.rb             | 45 ++++++++++++--------
 test/cgi/test_cgi_cookie.rb | 82 +++++++++++++++++++++++++++++++++++++
 test/cgi/test_cgi_header.rb |  8 ++++
 4 files changed, 154 insertions(+), 32 deletions(-)

diff --git a/lib/cgi/cookie.rb b/lib/cgi/cookie.rb
index 009566b..f26f015 100644
--- a/lib/cgi/cookie.rb
+++ b/lib/cgi/cookie.rb
@@ -40,6 +40,10 @@ class CGI
   class Cookie < Array
     @@accept_charset="UTF-8" unless defined?(@@accept_charset)
 
+    TOKEN_RE = %r"\A[[!-~]&&[^()<>@,;:\\\"/?=\[\]{}]]+\z"
+    PATH_VALUE_RE = %r"\A[[ -~]&&[^;]]*\z"
+    DOMAIN_VALUE_RE = %r"\A(?<label>(?!-)[-A-Za-z0-9]+(?<!-))(?:\.\g<label>)*\z"
+
     # Create a new CGI::Cookie object.
     #
     # :call-seq:
@@ -72,9 +76,8 @@ class CGI
       @domain = nil
       @expires = nil
       if name.kind_of?(String)
-        @name = name
-        %r|^(.*/)|.match(ENV["SCRIPT_NAME"])
-        @path = ($1 or "")
+        self.name = name
+        self.path = (%r|\A(.*/)| =~ ENV["SCRIPT_NAME"] ? $1 : "")
         @secure = false
         @httponly = false
         return super(value)
@@ -85,16 +88,11 @@ class CGI
         raise ArgumentError, "`name' required"
       end
 
-      @name = options["name"]
+      self.name = options["name"]
       value = Array(options["value"])
       # simple support for IE
-      if options["path"]
-        @path = options["path"]
-      else
-        %r|^(.*/)|.match(ENV["SCRIPT_NAME"])
-        @path = ($1 or "")
-      end
-      @domain = options["domain"]
+      self.path = options["path"] || (%r|\A(.*/)| =~ ENV["SCRIPT_NAME"] ? $1 : "")
+      self.domain = options["domain"]
       @expires = options["expires"]
       @secure = options["secure"] == true
       @httponly = options["httponly"] == true
@@ -102,12 +100,35 @@ class CGI
       super(value)
     end
 
-    # Name of this cookie, as a +String+
-    attr_accessor :name
+    attr_reader :name
+    # Set name of this cookie
+    def name=(str)
+      if str and !TOKEN_RE.match?(str)
+        raise ArgumentError, "invalid name: #{str.dump}"
+      end
+      @name = str
+    end
+
     # Path for which this cookie applies, as a +String+
-    attr_accessor :path
+    attr_reader :path
+    # Set path for which this cookie applies
+    def path=(str)
+      if str and !PATH_VALUE_RE.match?(str)
+        raise ArgumentError, "invalid path: #{str.dump}"
+      end
+      @path = str
+    end
+
     # Domain for which this cookie applies, as a +String+
-    attr_accessor :domain
+    attr_reader :domain
+    # Set domain for which this cookie applies
+    def domain=(str)
+      if str and ((str = str.b).bytesize > 255 or !DOMAIN_VALUE_RE.match?(str))
+        raise ArgumentError, "invalid domain: #{str.dump}"
+      end
+      @domain = str
+    end
+
     # Time at which this cookie expires, as a +Time+
     attr_accessor :expires
     # True if this cookie is secure; false otherwise
diff --git a/lib/cgi/core.rb b/lib/cgi/core.rb
index 9bd7798..7d8b223 100644
--- a/lib/cgi/core.rb
+++ b/lib/cgi/core.rb
@@ -188,17 +188,28 @@ class CGI
   # Using #header with the HTML5 tag maker will create a <header> element.
   alias :header :http_header
 
+  def _no_crlf_check(str)
+    if str
+      str = str.to_s
+      raise "A HTTP status or header field must not include CR and LF" if str =~ /[\r\n]/
+      str
+    else
+      nil
+    end
+  end
+  private :_no_crlf_check
+
   def _header_for_string(content_type) #:nodoc:
     buf = ''.dup
     if nph?()
-      buf << "#{$CGI_ENV['SERVER_PROTOCOL'] || 'HTTP/1.0'} 200 OK#{EOL}"
+      buf << "#{_no_crlf_check($CGI_ENV['SERVER_PROTOCOL']) || 'HTTP/1.0'} 200 OK#{EOL}"
       buf << "Date: #{CGI.rfc1123_date(Time.now)}#{EOL}"
-      buf << "Server: #{$CGI_ENV['SERVER_SOFTWARE']}#{EOL}"
+      buf << "Server: #{_no_crlf_check($CGI_ENV['SERVER_SOFTWARE'])}#{EOL}"
       buf << "Connection: close#{EOL}"
     end
-    buf << "Content-Type: #{content_type}#{EOL}"
+    buf << "Content-Type: #{_no_crlf_check(content_type)}#{EOL}"
     if @output_cookies
-      @output_cookies.each {|cookie| buf << "Set-Cookie: #{cookie}#{EOL}" }
+      @output_cookies.each {|cookie| buf << "Set-Cookie: #{_no_crlf_check(cookie)}#{EOL}" }
     end
     return buf
   end # _header_for_string
@@ -213,9 +224,9 @@ class CGI
     ## NPH
     options.delete('nph') if defined?(MOD_RUBY)
     if options.delete('nph') || nph?()
-      protocol = $CGI_ENV['SERVER_PROTOCOL'] || 'HTTP/1.0'
+      protocol = _no_crlf_check($CGI_ENV['SERVER_PROTOCOL']) || 'HTTP/1.0'
       status = options.delete('status')
-      status = HTTP_STATUS[status] || status || '200 OK'
+      status = HTTP_STATUS[status] || _no_crlf_check(status) || '200 OK'
       buf << "#{protocol} #{status}#{EOL}"
       buf << "Date: #{CGI.rfc1123_date(Time.now)}#{EOL}"
       options['server'] ||= $CGI_ENV['SERVER_SOFTWARE'] || ''
@@ -223,38 +234,38 @@ class CGI
     end
     ## common headers
     status = options.delete('status')
-    buf << "Status: #{HTTP_STATUS[status] || status}#{EOL}" if status
+    buf << "Status: #{HTTP_STATUS[status] || _no_crlf_check(status)}#{EOL}" if status
     server = options.delete('server')
-    buf << "Server: #{server}#{EOL}" if server
+    buf << "Server: #{_no_crlf_check(server)}#{EOL}" if server
     connection = options.delete('connection')
-    buf << "Connection: #{connection}#{EOL}" if connection
+    buf << "Connection: #{_no_crlf_check(connection)}#{EOL}" if connection
     type = options.delete('type')
-    buf << "Content-Type: #{type}#{EOL}" #if type
+    buf << "Content-Type: #{_no_crlf_check(type)}#{EOL}" #if type
     length = options.delete('length')
-    buf << "Content-Length: #{length}#{EOL}" if length
+    buf << "Content-Length: #{_no_crlf_check(length)}#{EOL}" if length
     language = options.delete('language')
-    buf << "Content-Language: #{language}#{EOL}" if language
+    buf << "Content-Language: #{_no_crlf_check(language)}#{EOL}" if language
     expires = options.delete('expires')
     buf << "Expires: #{CGI.rfc1123_date(expires)}#{EOL}" if expires
     ## cookie
     if cookie = options.delete('cookie')
       case cookie
       when String, Cookie
-        buf << "Set-Cookie: #{cookie}#{EOL}"
+        buf << "Set-Cookie: #{_no_crlf_check(cookie)}#{EOL}"
       when Array
         arr = cookie
-        arr.each {|c| buf << "Set-Cookie: #{c}#{EOL}" }
+        arr.each {|c| buf << "Set-Cookie: #{_no_crlf_check(c)}#{EOL}" }
       when Hash
         hash = cookie
-        hash.each_value {|c| buf << "Set-Cookie: #{c}#{EOL}" }
+        hash.each_value {|c| buf << "Set-Cookie: #{_no_crlf_check(c)}#{EOL}" }
       end
     end
     if @output_cookies
-      @output_cookies.each {|c| buf << "Set-Cookie: #{c}#{EOL}" }
+      @output_cookies.each {|c| buf << "Set-Cookie: #{_no_crlf_check(c)}#{EOL}" }
     end
     ## other headers
     options.each do |key, value|
-      buf << "#{key}: #{value}#{EOL}"
+      buf << "#{_no_crlf_check(key)}: #{_no_crlf_check(value)}#{EOL}"
     end
     return buf
   end # _header_for_hash
diff --git a/test/cgi/test_cgi_cookie.rb b/test/cgi/test_cgi_cookie.rb
index 985cc0d..7afff5e 100644
--- a/test/cgi/test_cgi_cookie.rb
+++ b/test/cgi/test_cgi_cookie.rb
@@ -60,6 +60,24 @@ class CGICookieTest < Test::Unit::TestCase
   end
 
 
+  def test_cgi_cookie_new_with_domain
+    h = {'name'=>'name1', 'value'=>'value1'}
+    cookie = CGI::Cookie.new({'domain' => 'a.example.com'}.merge(h))
+    assert_equal('a.example.com', cookie.domain)
+
+    cookie = CGI::Cookie.new({'domain'=>'1.example.com'}.merge(h))
+    assert_equal('1.example.com', cookie.domain, 'enhanced by RFC 1123')
+
+    assert_raise(ArgumentError) {
+      CGI::Cookie.new({'domain'=>'-a.example.com'}.merge(h))
+    }
+
+    assert_raise(ArgumentError) {
+      CGI::Cookie.new({'domain'=>'a-.example.com'}.merge(h))
+    }
+  end
+
+
   def test_cgi_cookie_scriptname
     cookie = CGI::Cookie.new('name1', 'value1')
     assert_equal('', cookie.path)
@@ -118,6 +136,70 @@ class CGICookieTest < Test::Unit::TestCase
   end
 
 
+  def test_cgi_cookie_domain_injection_into_name
+    name = "a=b; domain=example.com;"
+    path = "/"
+    domain = "example.jp"
+    assert_raise(ArgumentError) do
+      CGI::Cookie.new('name' => name,
+                      'value' => "value",
+                      'domain' => domain,
+                      'path' => path)
+    end
+  end
+
+
+  def test_cgi_cookie_newline_injection_into_name
+    name = "a=b;\r\nLocation: http://example.com#"
+    path = "/"
+    domain = "example.jp"
+    assert_raise(ArgumentError) do
+      CGI::Cookie.new('name' => name,
+                      'value' => "value",
+                      'domain' => domain,
+                      'path' => path)
+    end
+  end
+
+
+  def test_cgi_cookie_multibyte_injection_into_name
+    name = "a=b;\u3042"
+    path = "/"
+    domain = "example.jp"
+    assert_raise(ArgumentError) do
+      CGI::Cookie.new('name' => name,
+                      'value' => "value",
+                      'domain' => domain,
+                      'path' => path)
+    end
+  end
+
+
+  def test_cgi_cookie_injection_into_path
+    name = "name"
+    path = "/; samesite=none"
+    domain = "example.jp"
+    assert_raise(ArgumentError) do
+      CGI::Cookie.new('name' => name,
+                      'value' => "value",
+                      'domain' => domain,
+                      'path' => path)
+    end
+  end
+
+
+  def test_cgi_cookie_injection_into_domain
+    name = "name"
+    path = "/"
+    domain = "example.jp; samesite=none"
+    assert_raise(ArgumentError) do
+      CGI::Cookie.new('name' => name,
+                      'value' => "value",
+                      'domain' => domain,
+                      'path' => path)
+    end
+  end
+
 
   instance_methods.each do |method|
     private method if method =~ /^test_(.*)/ && $1 != ENV['TEST']
diff --git a/test/cgi/test_cgi_header.rb b/test/cgi/test_cgi_header.rb
index bab2d03..ec2f4de 100644
--- a/test/cgi/test_cgi_header.rb
+++ b/test/cgi/test_cgi_header.rb
@@ -176,6 +176,14 @@ class CGIHeaderTest < Test::Unit::TestCase
   end
 
 
+  def test_cgi_http_header_crlf_injection
+    cgi = CGI.new
+    assert_raise(RuntimeError) { cgi.http_header("text/xhtml\r\nBOO") }
+    assert_raise(RuntimeError) { cgi.http_header("type" => "text/xhtml\r\nBOO") }
+    assert_raise(RuntimeError) { cgi.http_header("status" => "200 OK\r\nBOO") }
+    assert_raise(RuntimeError) { cgi.http_header("location" => "text/xhtml\r\nBOO") }
+  end
+
 
   instance_methods.each do |method|
     private method if method =~ /^test_(.*)/ && $1 != ENV['TEST']
-- 
2.41.0