mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-21 12:30:06 +00:00
CVE-2013-2207, BZ #15755: Disable pt_chown.
The helper binary pt_chown tricked into granting access to another user's pseudo-terminal. Pre-conditions for the attack: * Attacker with local user account * Kernel with FUSE support * "user_allow_other" in /etc/fuse.conf * Victim with allocated slave in /dev/pts Using the setuid installed pt_chown and a weak check on whether a file descriptor is a tty, an attacker could fake a pty check using FUSE and trick pt_chown to grant ownership of a pty descriptor that the current user does not own. It cannot access /dev/pts/ptmx however. In most modern distributions pt_chown is not needed because devpts is enabled by default. The fix for this CVE is to disable building and using pt_chown by default. We still provide a configure option to enable hte use of pt_chown but distributions do so at their own risk.
This commit is contained in:
Carlos O'Donell
parent
da2d62df77
commit
e4608715e6
21
ChangeLog
21
ChangeLog
@ -1,3 +1,24 @@
|
||||
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.
|
||||
|
||||
2013-07-20 David S. Miller <davem@davemloft.net>
|
||||
|
||||
* sysdeps/sparc/fpu/libm-test-ulps: Update ULPs to handle minor
|
||||
|
||||
12
INSTALL
12
INSTALL
@ -136,6 +136,18 @@ will be used, and CFLAGS sets optimization options for the compiler.
|
||||
`--enable-lock-elision=yes'
|
||||
Enable lock elision for pthread mutexes by default.
|
||||
|
||||
`--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
|
||||
|
||||
9
NEWS
9
NEWS
@ -21,7 +21,14 @@ Version 2.18
|
||||
15395, 15405, 15406, 15409, 15416, 15418, 15419, 15423, 15424, 15426,
|
||||
15429, 15431, 15432, 15441, 15442, 15448, 15465, 15480, 15485, 15488,
|
||||
15490, 15492, 15493, 15497, 15506, 15529, 15536, 15553, 15577, 15583,
|
||||
15618, 15627, 15631, 15654, 15655, 15666, 15667, 15674, 15711.
|
||||
15618, 15627, 15631, 15654, 15655, 15666, 15667, 15674, 15711, 15755.
|
||||
|
||||
* 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.
|
||||
|
||||
* CVE-2013-0242 Buffer overrun in regexp matcher has been fixed (Bugzilla
|
||||
#15078).
|
||||
|
||||
@ -238,4 +238,7 @@
|
||||
/* 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
|
||||
|
||||
@ -95,6 +95,7 @@ link-obsolete-rpc = @link_obsolete_rpc@
|
||||
build-nscd = @build_nscd@
|
||||
use-nscd = @use_nscd@
|
||||
build-hardcoded-path-in-tests= @hardcoded_path_in_tests@
|
||||
build-pt-chown = @build_pt_chown@
|
||||
|
||||
# Build tools.
|
||||
CC = @CC@
|
||||
|
||||
16
configure
vendored
16
configure
vendored
@ -647,6 +647,7 @@ multi_arch
|
||||
base_machine
|
||||
add_on_subdirs
|
||||
add_ons
|
||||
build_pt_chown
|
||||
build_nscd
|
||||
link_obsolete_rpc
|
||||
libc_cv_nss_crypt
|
||||
@ -756,6 +757,7 @@ enable_obsolete_rpc
|
||||
enable_systemtap
|
||||
enable_build_nscd
|
||||
enable_nscd
|
||||
enable_pt_chown
|
||||
with_cpu
|
||||
'
|
||||
ac_precious_vars='build_alias
|
||||
@ -1421,6 +1423,7 @@ 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]
|
||||
@ -3711,6 +3714,19 @@ 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 $host_os
|
||||
|
||||
10
configure.in
10
configure.in
@ -353,6 +353,16 @@ AC_ARG_ENABLE([nscd],
|
||||
[use_nscd=$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 $host_os
|
||||
|
||||
@ -30,9 +30,15 @@ routines := getlogin getlogin_r setlogin getlogin_r_chk \
|
||||
|
||||
CFLAGS-grantpt.c = -DLIBEXECDIR='"$(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
|
||||
|
||||
@ -163,6 +163,20 @@ so that they can be invoked directly.
|
||||
@item --enable-lock-elision=yes
|
||||
Enable lock elision for pthread mutexes by default.
|
||||
|
||||
@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
|
||||
|
||||
@ -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)
|
||||
|
||||
@ -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>
|
||||
|
||||
Loading…
Reference in New Issue
Block a user