aboutsummaryrefslogtreecommitdiffstats
path: root/main/guile/CVE-2016-8606.patch
diff options
context:
space:
mode:
Diffstat (limited to 'main/guile/CVE-2016-8606.patch')
-rw-r--r--main/guile/CVE-2016-8606.patch337
1 files changed, 337 insertions, 0 deletions
diff --git a/main/guile/CVE-2016-8606.patch b/main/guile/CVE-2016-8606.patch
new file mode 100644
index 0000000000..2ba897db0b
--- /dev/null
+++ b/main/guile/CVE-2016-8606.patch
@@ -0,0 +1,337 @@
+From 08c021916dbd3a235a9f9cc33df4c418c0724e03 Mon Sep 17 00:00:00 2001
+From: Mark H Weaver <mhw@netris.org>
+Date: Fri, 9 Sep 2016 07:36:52 -0400
+Subject: REPL Server: Guard against HTTP inter-protocol exploitation attacks.
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Reported by Christopher Allan Webber <cwebber@dustycloud.org>
+Co-authored-by: Ludovic Court├Ęs <ludo@gnu.org>
+
+This commit adds protection to Guile's REPL servers against HTTP
+inter-protocol exploitation attacks, a scenario whereby an attacker can,
+via an HTML page, cause a web browser to send data to TCP servers
+listening on a loopback interface or private network. See
+<https://en.wikipedia.org/wiki/Inter-protocol_exploitation> and
+<https://www.jochentopf.com/hfpa/hfpa.pdf>, The HTML Form Protocol
+Attack (2001) by Tochen Topf <jochen@remote.org>.
+
+Here we add a procedure to 'before-read-hook' that looks for a possible
+HTTP request-line in the first line of input from the client socket. If
+present, the socket is drained and closed, and a loud warning is written
+to stderr (POSIX file descriptor 2).
+
+* module/system/repl/server.scm: Add 'maybe-check-for-http-request'
+to 'before-read-hook' when this module is loaded.
+(with-temporary-port-encoding, with-saved-port-line+column)
+(drain-input-and-close, permissive-http-request-line?)
+(check-for-http-request, guard-against-http-request)
+(maybe-check-for-http-request): New procedures.
+(serve-client): Use 'guard-against-http-request'.
+* module/system/repl/coop-server.scm (start-repl-client): Use
+'guard-against-http-request'.
+* doc/ref/guile-invoke.texi (Command-line Options): In the description
+of the --listen option, make the security warning more prominent.
+Mention the new protection added here. Recommend using UNIX domain
+sockets for REPL servers. "a path to" => "the file name of".
+---
+ doc/ref/guile-invoke.texi | 20 +++-
+ module/system/repl/coop-server.scm | 7 +-
+ module/system/repl/server.scm | 182 ++++++++++++++++++++++++++++++++++++-
+ 3 files changed, 201 insertions(+), 8 deletions(-)
+
+diff --git a/doc/ref/guile-invoke.texi b/doc/ref/guile-invoke.texi
+index 4cf833f..5be8f20 100644
+--- a/doc/ref/guile-invoke.texi
++++ b/doc/ref/guile-invoke.texi
+@@ -1,7 +1,7 @@
+ @c -*-texinfo-*-
+ @c This is part of the GNU Guile Reference Manual.
+-@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2010, 2011, 2013
+-@c Free Software Foundation, Inc.
++@c Copyright (C) 1996, 1997, 2000-2005, 2010, 2011, 2013, 2014,
++@c 2016 Free Software Foundation, Inc.
+ @c See the file guile.texi for copying conditions.
+
+ @node Invoking Guile
+@@ -176,7 +176,7 @@ the @file{.guile} file. @xref{Init File}.
+ While this program runs, listen on a local port or a path for REPL
+ clients. If @var{p} starts with a number, it is assumed to be a local
+ port on which to listen. If it starts with a forward slash, it is
+-assumed to be a path to a UNIX domain socket on which to listen.
++assumed to be the file name of a UNIX domain socket on which to listen.
+
+ If @var{p} is not given, the default is local port 37146. If you look
+ at it upside down, it almost spells ``Guile''. If you have netcat
+@@ -184,12 +184,22 @@ installed, you should be able to @kbd{nc localhost 37146} and get a
+ Guile prompt. Alternately you can fire up Emacs and connect to the
+ process; see @ref{Using Guile in Emacs} for more details.
+
+-Note that opening a port allows anyone who can connect to that port---in
+-the TCP case, any local user---to do anything Guile can do, as the user
++@quotation Note
++Opening a port allows anyone who can connect to that port to do anything
++Guile can do, as the user
+ that the Guile process is running as. Do not use @option{--listen} on
+ multi-user machines. Of course, if you do not pass @option{--listen} to
+ Guile, no port will be opened.
+
++Guile protects against the
++@uref{https://en.wikipedia.org/wiki/Inter-protocol_exploitation,
++@dfn{HTTP inter-protocol exploitation attack}}, a scenario whereby an
++attacker can, @i{via} an HTML page, cause a web browser to send data to
++TCP servers listening on a loopback interface or private network.
++Nevertheless, you are advised to use UNIX domain sockets, as in
++@code{--listen=/some/local/file}, whenever possible.
++@end quotation
++
+ That said, @option{--listen} is great for interactive debugging and
+ development.
+
+diff --git a/module/system/repl/coop-server.scm b/module/system/repl/coop-server.scm
+index c19dda1..ae31ce8 100644
+--- a/module/system/repl/coop-server.scm
++++ b/module/system/repl/coop-server.scm
+@@ -1,6 +1,6 @@
+ ;;; Cooperative REPL server
+
+-;; Copyright (C) 2014 Free Software Foundation, Inc.
++;; Copyright (C) 2014, 2016 Free Software Foundation, Inc.
+
+ ;; This library is free software; you can redistribute it and/or
+ ;; modify it under the terms of the GNU Lesser General Public
+@@ -29,7 +29,8 @@
+ #:select (start-repl* prompting-meta-read))
+ #:use-module ((system repl server)
+ #:select (run-server* make-tcp-server-socket
+- add-open-socket! close-socket!))
++ add-open-socket! close-socket!
++ guard-against-http-request))
+ #:export (spawn-coop-repl-server
+ poll-coop-repl-server))
+
+@@ -173,6 +174,8 @@ and output is sent over the socket CLIENT."
+ ;; another thread.
+ (add-open-socket! client (lambda () (close-fdes (fileno client))))
+
++ (guard-against-http-request client)
++
+ (with-continuation-barrier
+ (lambda ()
+ (coop-repl-prompt
+diff --git a/module/system/repl/server.scm b/module/system/repl/server.scm
+index ff9ee5c..9ece947 100644
+--- a/module/system/repl/server.scm
++++ b/module/system/repl/server.scm
+@@ -1,6 +1,6 @@
+ ;;; Repl server
+
+-;; Copyright (C) 2003, 2010, 2011, 2014 Free Software Foundation, Inc.
++;; Copyright (C) 2003, 2010, 2011, 2014, 2016 Free Software Foundation, Inc.
+
+ ;; This library is free software; you can redistribute it and/or
+ ;; modify it under the terms of the GNU Lesser General Public
+@@ -22,8 +22,13 @@
+ (define-module (system repl server)
+ #:use-module (system repl repl)
+ #:use-module (ice-9 threads)
++ #:use-module (ice-9 rdelim)
+ #:use-module (ice-9 match)
++ #:use-module (ice-9 iconv)
++ #:use-module (rnrs bytevectors)
++ #:use-module (rnrs io ports)
+ #:use-module (srfi srfi-1)
++ #:use-module (srfi srfi-26) ; cut
+ #:export (make-tcp-server-socket
+ make-unix-domain-server-socket
+ run-server
+@@ -154,6 +159,8 @@
+ ;; Arrange to cancel this thread to forcefully shut down the socket.
+ (add-open-socket! client (lambda () (cancel-thread thread))))
+
++ (guard-against-http-request client)
++
+ (with-continuation-barrier
+ (lambda ()
+ (parameterize ((current-input-port client)
+@@ -162,3 +169,176 @@
+ (current-warning-port client))
+ (with-fluids ((*repl-stack* '()))
+ (start-repl))))))
++
++
++;;;
++;;; The following code adds protection to Guile's REPL servers against
++;;; HTTP inter-protocol exploitation attacks, a scenario whereby an
++;;; attacker can, via an HTML page, cause a web browser to send data to
++;;; TCP servers listening on a loopback interface or private network.
++;;; See <https://en.wikipedia.org/wiki/Inter-protocol_exploitation> and
++;;; <https://www.jochentopf.com/hfpa/hfpa.pdf>, The HTML Form Protocol
++;;; Attack (2001) by Tochen Topf <jochen@remote.org>.
++;;;
++;;; Here we add a procedure to 'before-read-hook' that looks for a possible
++;;; HTTP request-line in the first line of input from the client socket. If
++;;; present, the socket is drained and closed, and a loud warning is written
++;;; to stderr (POSIX file descriptor 2).
++;;;
++
++(define (with-temporary-port-encoding port encoding thunk)
++ "Call THUNK in a dynamic environment in which the encoding of PORT is
++temporarily set to ENCODING."
++ (let ((saved-encoding #f))
++ (dynamic-wind
++ (lambda ()
++ (unless (port-closed? port)
++ (set! saved-encoding (port-encoding port))
++ (set-port-encoding! port encoding)))
++ thunk
++ (lambda ()
++ (unless (port-closed? port)
++ (set! encoding (port-encoding port))
++ (set-port-encoding! port saved-encoding))))))
++
++(define (with-saved-port-line+column port thunk)
++ "Save the line and column of PORT before entering THUNK, and restore
++their previous values upon normal or non-local exit from THUNK."
++ (let ((saved-line #f) (saved-column #f))
++ (dynamic-wind
++ (lambda ()
++ (unless (port-closed? port)
++ (set! saved-line (port-line port))
++ (set! saved-column (port-column port))))
++ thunk
++ (lambda ()
++ (unless (port-closed? port)
++ (set-port-line! port saved-line)
++ (set-port-column! port saved-column))))))
++
++(define (drain-input-and-close socket)
++ "Drain input from SOCKET using ISO-8859-1 encoding until it would block,
++and then close it. Return the drained input as a string."
++ (dynamic-wind
++ (lambda ()
++ ;; Enable full buffering mode on the socket to allow
++ ;; 'get-bytevector-some' to return non-trivial chunks.
++ (setvbuf socket _IOFBF))
++ (lambda ()
++ (let loop ((chunks '()))
++ (let ((result (and (char-ready? socket)
++ (get-bytevector-some socket))))
++ (if (bytevector? result)
++ (loop (cons (bytevector->string result "ISO-8859-1")
++ chunks))
++ (string-concatenate-reverse chunks)))))
++ (lambda ()
++ ;; Close the socket even in case of an exception.
++ (close-port socket))))
++
++(define permissive-http-request-line?
++ ;; This predicate is deliberately permissive
++ ;; when checking the Request-URI component.
++ (let ((cs (ucs-range->char-set #x20 #x7E))
++ (rx (make-regexp
++ (string-append
++ "^(OPTIONS|GET|HEAD|POST|PUT|DELETE|TRACE|CONNECT) "
++ "[^ ]+ "
++ "HTTP/[0-9]+.[0-9]+$"))))
++ (lambda (line)
++ "Return true if LINE might plausibly be an HTTP request-line,
++otherwise return #f."
++ ;; We cannot simplify this to a simple 'regexp-exec', because
++ ;; 'regexp-exec' cannot cope with NUL bytes.
++ (and (string-every cs line)
++ (regexp-exec rx line)))))
++
++(define (check-for-http-request socket)
++ "Check for a possible HTTP request in the initial input from SOCKET.
++If one is found, close the socket and print a report to STDERR (fdes 2).
++Otherwise, put back the bytes."
++ ;; Temporarily set the port encoding to ISO-8859-1 to allow lossless
++ ;; reading and unreading of the first line, regardless of what bytes
++ ;; are present. Note that a valid HTTP request-line contains only
++ ;; ASCII characters.
++ (with-temporary-port-encoding socket "ISO-8859-1"
++ (lambda ()
++ ;; Save the port 'line' and 'column' counters and later restore
++ ;; them, since unreading what we read is not sufficient to do so.
++ (with-saved-port-line+column socket
++ (lambda ()
++ ;; Read up to (but not including) the first CR or LF.
++ ;; Although HTTP mandates CRLF line endings, we are permissive
++ ;; here to guard against the possibility that in some
++ ;; environments CRLF might be converted to LF before it
++ ;; reaches us.
++ (match (read-delimited "\r\n" socket 'peek)
++ ((? eof-object?)
++ ;; We found EOF before any input. Nothing to do.
++ 'done)
++
++ ((? permissive-http-request-line? request-line)
++ ;; The input from the socket began with a plausible HTTP
++ ;; request-line, which is unlikely to be legitimate and may
++ ;; indicate an possible break-in attempt.
++
++ ;; First, set the current port parameters to a void-port,
++ ;; to avoid sending any more data over the socket, to cause
++ ;; the REPL reader to see EOF, and to swallow any remaining
++ ;; output gracefully.
++ (let ((void-port (%make-void-port "rw")))
++ (current-input-port void-port)
++ (current-output-port void-port)
++ (current-error-port void-port)
++ (current-warning-port void-port))
++
++ ;; Read from the socket until we would block,
++ ;; and then close it.
++ (let ((drained-input (drain-input-and-close socket)))
++
++ ;; Print a report to STDERR (POSIX file descriptor 2).
++ ;; XXX Can we do better here?
++ (call-with-port (dup->port 2 "w")
++ (cut format <> "
++@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
++@@ POSSIBLE BREAK-IN ATTEMPT ON THE REPL SERVER @@
++@@ BY AN HTTP INTER-PROTOCOL EXPLOITATION ATTACK. See: @@
++@@ <https://en.wikipedia.org/wiki/Inter-protocol_exploitation> @@
++@@ Possible HTTP request received: ~S
++@@ The associated socket has been closed. @@
++@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\n"
++ (string-append request-line
++ drained-input)))))
++
++ (start-line
++ ;; The HTTP request-line was not found, so
++ ;; 'unread' the characters that we have read.
++ (unread-string start-line socket))))))))
++
++(define (guard-against-http-request socket)
++ "Arrange for the Guile REPL to check for an HTTP request in the
++initial input from SOCKET, in which case the socket will be closed.
++This guards against HTTP inter-protocol exploitation attacks, a scenario
++whereby an attacker can, via an HTML page, cause a web browser to send
++data to TCP servers listening on a loopback interface or private
++network."
++ (%set-port-property! socket 'guard-against-http-request? #t))
++
++(define* (maybe-check-for-http-request
++ #:optional (socket (current-input-port)))
++ "Apply check-for-http-request to SOCKET if previously requested by
++guard-against-http-request. This procedure is intended to be added to
++before-read-hook."
++ (when (%port-property socket 'guard-against-http-request?)
++ (check-for-http-request socket)
++ (unless (port-closed? socket)
++ (%set-port-property! socket 'guard-against-http-request? #f))))
++
++;; Install the hook.
++(add-hook! before-read-hook
++ maybe-check-for-http-request)
++
++;;; Local Variables:
++;;; eval: (put 'with-temporary-port-encoding 'scheme-indent-function 2)
++;;; eval: (put 'with-saved-port-line+column 'scheme-indent-function 1)
++;;; End:
+--
+cgit v1.0
+