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authorUlrich Drepper <drepper@redhat.com>2009-06-16 15:58:07 -0700
committerUlrich Drepper <drepper@redhat.com>2009-06-16 15:58:07 -0700
commitf793b62438a3cfdbcc5ba453eebee1db3f315bea (patch)
treec0c8cf38a5c5293bfc05af20ab797e2496137158 /login
parentfab8238de69de67637d21923b3ec1c26e4ce8450 (diff)
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Extend pt_chown to drop privileges.
If libcap is available, use it to drop privileges in pt_chown before starting the work to change the permissions and ownership of the slave device.
Diffstat (limited to 'login')
-rw-r--r--login/Makefile7
-rw-r--r--login/programs/pt_chown.c45
2 files changed, 44 insertions, 8 deletions
diff --git a/login/Makefile b/login/Makefile
index b02d385b66..427c050a89 100644
--- a/login/Makefile
+++ b/login/Makefile
@@ -1,4 +1,4 @@
-# Copyright (C) 1996-1998,2000-2002,2003,2007 Free Software Foundation, Inc.
+# Copyright (C) 1996-1998,2000-2003,2007, 2009 Free Software Foundation, Inc.
# This file is part of the GNU C Library.
# The GNU C Library is free software; you can redistribute it and/or
@@ -54,6 +54,11 @@ otherlibs += $(nssobjdir)/libnss_files.a $(resolvobjdir)/libnss_dns.a \
$(resolvobjdir)/libresolv.a $(common-objpfx)libc.a
endif
+ifeq (yes,$(have-libcap))
+libcap = -lcap
+endif
+LDLIBS-pt_chown = $(libcap)
+
# pt_chown needs to be setuid root.
$(inst_libexecdir)/pt_chown: $(objpfx)pt_chown $(+force)
$(make-target-directory)
diff --git a/login/programs/pt_chown.c b/login/programs/pt_chown.c
index 5167b29225..7e279a5f3b 100644
--- a/login/programs/pt_chown.c
+++ b/login/programs/pt_chown.c
@@ -29,6 +29,10 @@
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
+#ifdef HAVE_LIBCAP
+# include <sys/capability.h>
+# include <sys/prctl.h>
+#endif
#include "pty-private.h"
@@ -99,7 +103,7 @@ static int
do_pt_chown (void)
{
char *pty;
- struct stat st;
+ struct stat64 st;
struct group *p;
gid_t gid;
@@ -110,7 +114,7 @@ do_pt_chown (void)
/* Check that the returned slave pseudo terminal is a
character device. */
- if (stat (pty, &st) < 0 || !S_ISCHR(st.st_mode))
+ if (stat64 (pty, &st) < 0 || !S_ISCHR (st.st_mode))
return FAIL_EINVAL;
/* Get the group ID of the special `tty' group. */
@@ -136,16 +140,43 @@ int
main (int argc, char *argv[])
{
uid_t euid = geteuid ();
+ uid_t uid = getuid ();
int remaining;
- /* Normal invocation of this program is with no arguments and
- with privileges.
- FIXME: Should use capable (CAP_CHOWN|CAP_FOWNER). */
if (argc == 1 && euid == 0)
- return do_pt_chown ();
+ {
+#ifdef HAVE_LIBCAP
+ /* Drop privileges. */
+ if (uid != euid)
+ {
+ static const cap_value_t cap_list[] =
+ { CAP_CHOWN, CAP_FOWNER };
+# define ncap_list (sizeof (cap_list) / sizeof (cap_list[0]))
+ cap_t caps = cap_init ();
+ if (caps == NULL)
+ error (FAIL_ENOMEM, errno,
+ _("Failed to initialize drop of capabilities"));
+
+ /* There is no reason why these should not work. */
+ cap_set_flag (caps, CAP_PERMITTED, ncap_list, cap_list, CAP_SET);
+ cap_set_flag (caps, CAP_EFFECTIVE, ncap_list, cap_list, CAP_SET);
+
+ int res = cap_set_proc (caps);
+
+ cap_free (caps);
+
+ if (__builtin_expect (res != 0, 0))
+ error (FAIL_EXEC, errno, _("cap_set_proc failed"));
+ }
+#endif
+
+ /* Normal invocation of this program is with no arguments and
+ with privileges. */
+ return do_pt_chown ();
+ }
/* We aren't going to be using privileges, so drop them right now. */
- setuid (getuid ());
+ setuid (uid);
/* Set locale via LC_ALL. */
setlocale (LC_ALL, "");