Blob Blame History Raw
#* CVE-2013-2207 Incorrectly granting access to another user's pseudo-terminal
#  has been fixed by disabling the use of pt_chown (Bugzilla #15755).
#  Distributions can re-enable building and using pt_chown via the new configure
#  option `--enable-pt_chown'.  Enabling the use of pt_chown carries with it
#  considerable security risks and should only be used if the distribution
#  understands and accepts the risks.
#
#2013-07-21  Siddhesh Poyarekar  <siddhesh@redhat.com>
#	    Andreas Schwab  <schwab@suse.de>
#	    Roland McGrath  <roland@hack.frob.com>
#	    Joseph Myers  <joseph@codesourcery.com>
#	    Carlos O'Donell  <carlos@redhat.com>
#
#	[BZ #15755]
#	* config.h.in: Define HAVE_PT_CHOWN.
#	* config.make.in (build-pt-chown): New variable.
#	* configure.in (--enable-pt_chown): New configure option.
#	* configure: Regenerate.
#	* login/Makefile: Include Makeconfig.  Build pt_chown only if
#	build-pt-chown is enabled.
#	* sysdeps/unix/grantpt.c (grantpt) [HAVE_PT_CHOWN]: Spawn
#	pt_chown to fix pty ownership.
#	* sysdeps/unix/sysv/linux/grantpt.c [HAVE_PT_CHOWN]: Define
#	CLOSE_ALL_FDS.
#	* manual/install.texi (Configuring and compiling): Mention
#	--enable-pt_chown. Add @findex for grantpt.
#	* INSTALL: Regenerate.
#
diff -Nru glibc-2.17-c758a686/config.h.in glibc-2.17-c758a686/config.h.in
--- glibc-2.17-c758a686/config.h.in	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/config.h.in	2013-07-24 00:20:07.651301252 -0400
@@ -232,4 +232,7 @@
 /* The ARM hard-float ABI is being used.  */
 #undef HAVE_ARM_PCS_VFP
 
+/* The pt_chown binary is being built and used by grantpt.  */
+#undef HAVE_PT_CHOWN
+
 #endif
diff -Nru glibc-2.17-c758a686/config.make.in glibc-2.17-c758a686/config.make.in
--- glibc-2.17-c758a686/config.make.in	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/config.make.in	2013-07-24 00:21:15.244176098 -0400
@@ -101,6 +101,7 @@ force-install = @force_install@
 link-obsolete-rpc = @link_obsolete_rpc@
 build-nscd = @build_nscd@
 use-nscd = @use_nscd@
+build-pt-chown = @build_pt_chown@
 
 # Build tools.
 CC = @CC@
diff -Nru glibc-2.17-c758a686/configure glibc-2.17-c758a686/configure
--- glibc-2.17-c758a686/configure	2013-07-24 00:25:10.090174244 -0400
+++ glibc-2.17-c758a686/configure	2013-07-24 00:20:07.769174345 -0400
@@ -653,6 +653,7 @@ multi_arch
 base_machine
 add_on_subdirs
 add_ons
+build_pt_chown
 build_nscd
 link_obsolete_rpc
 libc_cv_nss_crypt
@@ -759,6 +760,7 @@ enable_obsolete_rpc
 enable_systemtap
 enable_build_nscd
 enable_nscd
+enable_pt_chown
 with_cpu
 '
       ac_precious_vars='build_alias
@@ -1419,6 +1421,7 @@ Optional Features:
   --enable-systemtap      enable systemtap static probe points [default=no]
   --disable-build-nscd    disable building and installing the nscd daemon
   --disable-nscd          library functions will not contact the nscd daemon
+  --enable-pt_chown       Enable building and installing pt_chown
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -3934,6 +3937,19 @@ else
 fi
 
 
+# Check whether --enable-pt_chown was given.
+if test "${enable_pt_chown+set}" = set; then :
+  enableval=$enable_pt_chown; build_pt_chown=$enableval
+else
+  build_pt_chown=no
+fi
+
+
+if test $build_pt_chown = yes; then
+  $as_echo "#define HAVE_PT_CHOWN 1" >>confdefs.h
+
+fi
+
 # The way shlib-versions is used to generate soversions.mk uses a
 # fairly simplistic model for name recognition that can't distinguish
 # i486-pc-linux-gnu fully from i486-pc-gnu.  So we mutate a $host_os
diff -Nru glibc-2.17-c758a686/configure.in glibc-2.17-c758a686/configure.in
--- glibc-2.17-c758a686/configure.in	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/configure.in	2013-07-24 00:20:07.658298658 -0400
@@ -315,6 +315,16 @@ AC_ARG_ENABLE([nscd],
 	      [use_nscd=$enableval],
 	      [use_nscd=yes])
 
+AC_ARG_ENABLE([pt_chown],
+	      [AS_HELP_STRING([--enable-pt_chown],
+	       [Enable building and installing pt_chown])],
+	      [build_pt_chown=$enableval],
+	      [build_pt_chown=no])
+AC_SUBST(build_pt_chown)
+if test $build_pt_chown = yes; then
+  AC_DEFINE(HAVE_PT_CHOWN)
+fi
+
 # The way shlib-versions is used to generate soversions.mk uses a
 # fairly simplistic model for name recognition that can't distinguish
 # i486-pc-linux-gnu fully from i486-pc-gnu.  So we mutate a $host_os
diff -Nru glibc-2.17-c758a686/INSTALL glibc-2.17-c758a686/INSTALL
--- glibc-2.17-c758a686/INSTALL	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/INSTALL	2013-07-24 00:20:07.650300624 -0400
@@ -128,6 +128,18 @@ will be used, and CFLAGS sets optimizati
      this can be prevented though there generally is no reason since it
      creates compatibility problems.
 
+`--enable-pt_chown'
+     The file `pt_chown' is a helper binary for `grantpt' (*note
+     Pseudo-Terminals: Allocation.) that is installed setuid root to
+     fix up pseudo-terminal ownership.  It is not built by default
+     because systems using the Linux kernel are commonly built with the
+     `devpts' filesystem enabled and mounted at `/dev/pts', which
+     manages pseudo-terminal ownership automatically.  By using
+     `--enable-pt_chown', you may build `pt_chown' and install it
+     setuid and owned by `root'.  The use of `pt_chown' introduces
+     additional security risks to the system and you should enable it
+     only if you understand and accept those risks.
+
 `--build=BUILD-SYSTEM'
 `--host=HOST-SYSTEM'
      These options are for cross-compiling.  If you specify both
diff -Nru glibc-2.17-c758a686/login/Makefile glibc-2.17-c758a686/login/Makefile
--- glibc-2.17-c758a686/login/Makefile	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/login/Makefile	2013-07-24 00:20:07.660298670 -0400
@@ -29,9 +29,15 @@ routines := getutent getutent_r getutid 
 
 CFLAGS-grantpt.c = -DLIBEXECDIR='"$(libexecdir)"'
 
-others = utmpdump pt_chown
+others = utmpdump
+
+include ../Makeconfig
+
+ifeq (yes,$(build-pt-chown))
+others += pt_chown
 others-pie = pt_chown
 install-others-programs = $(inst_libexecdir)/pt_chown
+endif
 
 subdir-dirs = programs
 vpath %.c programs
diff -Nru glibc-2.17-c758a686/manual/install.texi glibc-2.17-c758a686/manual/install.texi
--- glibc-2.17-c758a686/manual/install.texi	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/manual/install.texi	2013-07-24 00:20:07.662298261 -0400
@@ -155,6 +155,20 @@ if the used tools support it.  By using 
 prevented though there generally is no reason since it creates
 compatibility problems.
 
+@pindex pt_chown
+@findex grantpt
+@item --enable-pt_chown
+The file @file{pt_chown} is a helper binary for @code{grantpt}
+(@pxref{Allocation, Pseudo-Terminals}) that is installed setuid root to
+fix up pseudo-terminal ownership.  It is not built by default because
+systems using the Linux kernel are commonly built with the @code{devpts}
+filesystem enabled and mounted at @file{/dev/pts}, which manages
+pseudo-terminal ownership automatically.  By using
+@samp{--enable-pt_chown}, you may build @file{pt_chown} and install it
+setuid and owned by @code{root}.  The use of @file{pt_chown} introduces
+additional security risks to the system and you should enable it only if
+you understand and accept those risks.
+
 @item --build=@var{build-system}
 @itemx --host=@var{host-system}
 These options are for cross-compiling.  If you specify both options and
diff -Nru glibc-2.17-c758a686/sysdeps/unix/grantpt.c glibc-2.17-c758a686/sysdeps/unix/grantpt.c
--- glibc-2.17-c758a686/sysdeps/unix/grantpt.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/sysdeps/unix/grantpt.c	2013-07-24 00:20:07.663299235 -0400
@@ -173,9 +173,10 @@ grantpt (int fd)
   retval = 0;
   goto cleanup;
 
-  /* We have to use the helper program.  */
+  /* We have to use the helper program if it is available.  */
  helper:;
 
+#ifdef HAVE_PT_CHOWN
   pid_t pid = __fork ();
   if (pid == -1)
     goto cleanup;
@@ -190,9 +191,9 @@ grantpt (int fd)
 	if (__dup2 (fd, PTY_FILENO) < 0)
 	  _exit (FAIL_EBADF);
 
-#ifdef CLOSE_ALL_FDS
+# ifdef CLOSE_ALL_FDS
       CLOSE_ALL_FDS ();
-#endif
+# endif
 
       execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL);
       _exit (FAIL_EXEC);
@@ -231,6 +232,7 @@ grantpt (int fd)
 	    assert(! "getpt: internal error: invalid exit code from pt_chown");
 	  }
     }
+#endif
 
  cleanup:
   if (buf != _buf)
diff -Nru glibc-2.17-c758a686/sysdeps/unix/sysv/linux/grantpt.c glibc-2.17-c758a686/sysdeps/unix/sysv/linux/grantpt.c
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/grantpt.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/grantpt.c	2013-07-24 00:20:07.664298465 -0400
@@ -11,7 +11,7 @@
 
 #include "pty-private.h"
 
-
+#if HAVE_PT_CHOWN
 /* Close all file descriptors except the one specified.  */
 static void
 close_all_fds (void)
@@ -38,6 +38,7 @@ close_all_fds (void)
       __dup2 (STDOUT_FILENO, STDERR_FILENO);
     }
 }
-#define CLOSE_ALL_FDS() close_all_fds()
+# define CLOSE_ALL_FDS() close_all_fds()
+#endif
 
 #include <sysdeps/unix/grantpt.c>