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