Don't load configs from user directory when setuid

When running as setuid() or setgid() don't access the user's home
directory, or use $HOME environment variables.

https://bugzilla.redhat.com/show_bug.cgi?id=985014

17 files changed, 423 insertions, 3 deletions

diff --git a/common/compat.c b/common/compat.c
index 5efc932..3b1361c 100644
--- a/common/compat.c
+++ b/common/compat.c
@@ -759,3 +759,51 @@ mkdtemp (char *template)
 }
 
 #endif /* HAVE_MKDTEMP */
+
+#ifndef HAVE_GETAUXVAL
+
+unsigned long
+getauxval (unsigned long type)
+{
+	static unsigned long secure = 0UL;
+	static bool check_secure_initialized = false;
+
+	/*
+	 * This is the only one our stand-in impl supports and is
+	 * also the only type we define in compat.h header
+	 */
+	assert (type == AT_SECURE);
+
+	if (!check_secure_initialized) {
+#if defined(HAVE___LIBC_ENABLE_SECURE)
+		extern int __libc_enable_secure;
+		secure = __libc_enable_secure;
+
+#elif defined(HAVE_ISSETUGID)
+		secure = issetugid ();
+
+#elif defined(OS_UNIX)
+		uid_t ruid, euid, suid; /* Real, effective and saved user ID's */
+		gid_t rgid, egid, sgid; /* Real, effective and saved group ID's */
+
+#ifdef HAVE_GETRESUID
+		if (getresuid (&ruid, &euid, &suid) != 0 ||
+		    getresgid (&rgid, &egid, &sgid) != 0)
+#endif /* HAVE_GETRESUID */
+		{
+			suid = ruid = getuid ();
+			sgid = rgid = getgid ();
+			euid = geteuid ();
+			egid = getegid ();
+		}
+
+		secure = (ruid != euid || ruid != suid ||
+		          rgid != egid || rgid != sgid);
+#endif /* OS_UNIX */
+		check_secure_initialized = true;
+	}
+
+	return secure;
+}
+
+#endif /* HAVE_GETAUXVAL */
diff --git a/common/compat.h b/common/compat.h
index 20f9a81..1cedc35 100644
--- a/common/compat.h
+++ b/common/compat.h
@@ -298,4 +298,16 @@ time_t      timegm          (struct tm *tm);
 
 #endif /* HAVE_TIMEGM */
 
+#ifdef HAVE_GETAUXVAL
+
+#include <sys/auxv.h>
+
+#else /* !HAVE_GETAUXVAL */
+
+unsigned long     getauxval (unsigned long type);
+
+#define AT_SECURE 23
+
+#endif /* !HAVE_GETAUXVAL */
+
 #endif /* __COMPAT_H__ */
diff --git a/common/path.c b/common/path.c
index 0ff1431..d807301 100644
--- a/common/path.c
+++ b/common/path.c
@@ -99,6 +99,11 @@ expand_homedir (const char *remainder)
 	if (remainder[0] == '\0')
 		remainder = NULL;
 
+	if (getauxval (AT_SECURE)) {
+		errno = EPERM;
+		return NULL;
+	}
+
 	env = getenv ("HOME");
 	if (env && env[0]) {
 		return p11_path_build (env, remainder, NULL);
diff --git a/common/test.c b/common/test.c
index 0f5c451..eb02645 100644
--- a/common/test.c
+++ b/common/test.c
@@ -48,6 +48,12 @@
 #include <stdlib.h>
 #include <string.h>
 
+#ifdef OS_UNIX
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#endif
+
 enum {
 	FIXTURE,
 	TEST,
@@ -331,3 +337,96 @@ p11_test_directory (const char *prefix)
 	free (templ);
 	return directory;
 }
+
+#ifdef OS_UNIX
+
+static void
+copy_file (const char *input,
+           int fd)
+{
+	p11_mmap *mmap;
+	const char *data;
+	ssize_t written;
+	size_t size;
+
+	mmap = p11_mmap_open (input, (void **)&data, &size);
+	assert (mmap != NULL);
+
+	while (size > 0) {
+		written = write (fd, data, size);
+		assert (written >= 0);
+
+		data += written;
+		size -= written;
+	}
+
+	p11_mmap_close (mmap);
+}
+
+char *
+p11_test_copy_setgid (const char *input)
+{
+	gid_t groups[128];
+		char *path;
+		gid_t group = 0;
+		int ret;
+		int fd;
+		int i;
+
+	ret = getgroups (128, groups);
+	for (i = 0; i < ret; ++i) {
+		if (groups[i] != getgid ()) {
+			group = groups[i];
+			break;
+		}
+	}
+	if (i == ret) {
+		fprintf (stderr, "# no suitable group, skipping test");
+		return NULL;
+	}
+
+	path = strdup ("/tmp/test-setgid.XXXXXX");
+	assert (path != NULL);
+
+	fd = mkstemp (path);
+	assert (fd >= 0);
+
+	copy_file (input, fd);
+	if (fchown (fd, getuid (), group) < 0)
+		assert_not_reached ();
+	if (fchmod (fd, 02750) < 0)
+		assert_not_reached ();
+	if (close (fd) < 0)
+		assert_not_reached ();
+
+	return path;
+}
+
+int
+p11_test_run_child (const char **argv,
+                    bool quiet_out)
+{
+	pid_t child;
+	int status;
+
+	child = fork ();
+	assert (child >= 0);
+
+	/* In the child process? */
+	if (child == 0) {
+		if (quiet_out)
+			close (1); /* stdout */
+		execve (argv[0], (char **)argv, NULL);
+		assert_not_reached ();
+	}
+
+	if (waitpid (child, &status, 0) < 0)
+		assert_not_reached ();
+
+	assert (!WIFSIGNALED (status));
+	assert (WIFEXITED (status));
+
+	return WEXITSTATUS (status);
+}
+
+#endif /* OS_UNIX */
diff --git a/common/test.h b/common/test.h
index 7354595..c9f519a 100644
--- a/common/test.h
+++ b/common/test.h
@@ -130,4 +130,13 @@ int         p11_test_run            (int argc,
 
 char *      p11_test_directory      (const char *prefix);
 
+#ifdef OS_UNIX
+
+char *      p11_test_copy_setgid    (const char *path);
+
+int         p11_test_run_child      (const char **argv,
+                                     bool quiet_out);
+
+#endif
+
 #endif /* P11_TEST_H_ */
diff --git a/common/tests/Makefile.am b/common/tests/Makefile.am
index 637399b..b1a42bd 100644
--- a/common/tests/Makefile.am
+++ b/common/tests/Makefile.am
@@ -7,7 +7,9 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir) \
 	-I$(srcdir)/.. \
 	-I$(COMMON) \
-	$(TEST_CFLAGS)
+	-DBUILDDIR=\"$(abs_builddir)\" \
+	$(TEST_CFLAGS) \
+	$(CUTEST_CFLAGS)
 
 LDADD = \
 	$(NULL)
@@ -26,6 +28,7 @@ CHECK_PROGS = \
 	$(NULL)
 
 noinst_PROGRAMS = \
+	frob-getauxval \
 	$(CHECK_PROGS)
 
 TESTS = $(CHECK_PROGS)
diff --git a/common/tests/frob-getauxval.c b/common/tests/frob-getauxval.c
new file mode 100644
index 0000000..54ebea0
--- /dev/null
+++ b/common/tests/frob-getauxval.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2013 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * Redistributions in binary form must reproduce the
+ *       above copyright notice, this list of conditions and
+ *       the following disclaimer in the documentation and/or
+ *       other materials provided with the distribution.
+ *     * The names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Author: Stef Walter <stefw@gnome.org>
+ */
+
+#include "config.h"
+#include "compat.h"
+
+#include <libtasn1.h>
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int
+main (int argc,
+      char *argv[])
+{
+	unsigned long type = 0;
+	unsigned long ret;
+
+	if (argc == 2)
+		type = atoi (argv[1]);
+
+	if (type == 0) {
+		fprintf (stderr, "usage: frob-getauxval 23");
+		abort ();
+	}
+
+	ret = getauxval (type);
+	printf ("getauxval(%lu) == %lu\n", type, ret);
+	return (int)ret;
+}
diff --git a/common/tests/test-compat.c b/common/tests/test-compat.c
index f1960ce..a541235 100644
--- a/common/tests/test-compat.c
+++ b/common/tests/test-compat.c
@@ -35,6 +35,7 @@
 #include "config.h"
 #include "test.h"
 
+#include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -56,10 +57,39 @@ test_strndup (void)
 	free (res);
 }
 
+#ifdef OS_UNIX
+
+static void
+test_getauxval (void)
+{
+	/* 23 is AT_SECURE */
+	const char *args[] = { BUILDDIR "/frob-getauxval", "23", NULL };
+	char *path;
+	int ret;
+
+	ret = p11_test_run_child (args, true);
+	assert_num_eq (ret, 0);
+
+	path = p11_test_copy_setgid (args[0]);
+	if (path == NULL)
+		return;
+
+	args[0] = path;
+	ret = p11_test_run_child (args, true);
+	assert_num_cmp (ret, !=, 0);
+
+	if (unlink (path) < 0)
+		assert_fail ("unlink failed", strerror (errno));
+	free (path);
+}
+
+#endif /* OS_UNIX */
+
 int
 main (int argc,
       char *argv[])
 {
 	p11_test (test_strndup, "/test/strndup");
+	p11_test (test_getauxval, "/test/getauxval");
 	return p11_test_run (argc, argv);
 }
diff --git a/configure.ac b/configure.ac
index b0bbbd5..2f92b8c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -79,6 +79,7 @@ if test "$os_unix" = "yes"; then
 	# These are thngs we can work around
 	AC_CHECK_MEMBERS([struct dirent.d_type],,,[#include <dirent.h>])
 	AC_CHECK_FUNCS([getprogname getexecname basename mkstemp mkdtemp])
+	AC_CHECK_FUNCS([getauxval issetugid getresuid])
 	AC_CHECK_FUNCS([strnstr memdup strndup])
 	AC_CHECK_FUNCS([asprintf vasprintf vsnprintf])
 	AC_CHECK_FUNCS([timegm])
@@ -100,6 +101,8 @@ if test "$os_unix" = "yes"; then
 	AC_CHECK_DECLS([__progname])
 	AC_LINK_IFELSE([AC_LANG_SOURCE([extern char *__progname; void main() { }])],
 		[AC_DEFINE(HAVE___PROGNAME, [1], [Whether __progname available])])
+	AC_LINK_IFELSE([AC_LANG_SOURCE([extern int __libc_enable_secure; void main() { }])],
+		[AC_DEFINE(HAVE___LIBC_ENABLE_SECURE, [1], [Whether __libc_enable_secure available])])
 fi
 
 AC_CHECK_LIB(intl, dgettext)
diff --git a/doc/manual/p11-kit-config.xml b/doc/manual/p11-kit-config.xml
index 6d069dd..1df55b1 100644
--- a/doc/manual/p11-kit-config.xml
+++ b/doc/manual/p11-kit-config.xml
@@ -87,5 +87,8 @@ critical: yes
 
 	<para><link linkend="pkcs11.conf">See the manual page</link> for more details
 	on the format and available options.</para>
+
+	<para>Note that user configuration files are not loaded from the home
+	directory if running inside a setuid or setgid program.</para>
 </section>
 </chapter>
diff --git a/doc/manual/pkcs11.conf.xml b/doc/manual/pkcs11.conf.xml
index 1ff2562..cda02ee 100644
--- a/doc/manual/pkcs11.conf.xml
+++ b/doc/manual/pkcs11.conf.xml
@@ -241,6 +241,9 @@ x-custom : text
 	file per module. In addition the <literal>~/.pkcs11/modules</literal> directory
 	can be used for modules installed by the user.</para>
 
+	<para>Note that user configuration files are not loaded from the home
+	directory if running inside a setuid or setgid program.</para>
+
 	<para>The default system config file and module directory can be changed
 	when building p11-kit. Always
 	<link linkend="devel-paths">lookup these paths</link> using
diff --git a/p11-kit/conf.c b/p11-kit/conf.c
index e699e66..d29d9ec 100644
--- a/p11-kit/conf.c
+++ b/p11-kit/conf.c
@@ -227,6 +227,11 @@ _p11_conf_load_globals (const char *system_conf, const char *user_conf,
 		goto finished;
 	}
 
+	if (mode != CONF_USER_NONE && getauxval (AT_SECURE)) {
+		p11_debug ("skipping user config in setuid or setgid program");
+		mode = CONF_USER_NONE;
+	}
+
 	if (mode != CONF_USER_NONE) {
 		path = p11_path_expand (user_conf);
 		if (!path) {
diff --git a/p11-kit/tests/Makefile.am b/p11-kit/tests/Makefile.am
index 6963850..16ba280 100644
--- a/p11-kit/tests/Makefile.am
+++ b/p11-kit/tests/Makefile.am
@@ -40,6 +40,7 @@ endif
 
 noinst_PROGRAMS = \
 	print-messages \
+	frob-setuid \
 	$(CHECK_PROGS)
 
 TESTS = $(CHECK_PROGS)
diff --git a/p11-kit/tests/files/system-modules/one.module b/p11-kit/tests/files/system-modules/one.module
index 15cb7f2..5f49a8f 100644
--- a/p11-kit/tests/files/system-modules/one.module
+++ b/p11-kit/tests/files/system-modules/one.module
@@ -1,4 +1,5 @@
 
 module: mock-one.so
 setting: system1
-trust-policy: yes
\ No newline at end of file
+trust-policy: yes
+number: 18
diff --git a/p11-kit/tests/files/user-modules/one.module b/p11-kit/tests/files/user-modules/one.module
index 6f1a2e8..5197daf 100644
--- a/p11-kit/tests/files/user-modules/one.module
+++ b/p11-kit/tests/files/user-modules/one.module
@@ -1,3 +1,4 @@
 
 setting: user1
-managed: yes
\ No newline at end of file
+managed: yes
+number: 33
diff --git a/p11-kit/tests/frob-setuid.c b/p11-kit/tests/frob-setuid.c
new file mode 100644
index 0000000..e546ece
--- /dev/null
+++ b/p11-kit/tests/frob-setuid.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2012 Red Hat Inc
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * Redistributions in binary form must reproduce the
+ *       above copyright notice, this list of conditions and
+ *       the following disclaimer in the documentation and/or
+ *       other materials provided with the distribution.
+ *     * The names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Author: Stef Walter <stefw@redhat.com>
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "compat.h"
+#include "p11-kit.h"
+
+int
+main (void)
+{
+	CK_FUNCTION_LIST **modules;
+	CK_FUNCTION_LIST *module;
+	char *field;
+	char *name;
+	int ret;
+	int i;
+
+	/*
+	 * Use 'chmod ug+s frob-setuid' to change this program
+	 * and test the output with/without setuid or setgid.
+	 */
+
+	putenv ("P11_KIT_STRICT=1");
+
+	modules = p11_kit_modules_load_and_initialize (0);
+	assert (modules != NULL);
+
+	/* This is a system configured module */
+	module = p11_kit_module_for_name (modules, "one");
+	assert (module != NULL);
+
+	field = p11_kit_config_option (module, "setting");
+	printf ("'setting' on module 'one': %s\n", field ? field : "(null)");
+
+	assert (field != NULL);
+	if (getauxval (AT_SECURE))
+		assert (strcmp (field, "system1") == 0);
+	else
+		assert (strcmp (field, "user1") == 0);
+
+	free (field);
+
+	for (i = 0; modules[i] != NULL; i++) {
+		name = p11_kit_module_get_name (modules[i]);
+		printf ("%s\n", name);
+		free (name);
+	}
+
+	field = p11_kit_config_option (module, "number");
+	printf ("'number' on module 'one': %s\n", field ? field : "(null)");
+
+	ret = atoi (field ? field : "0");
+	assert (ret != 0);
+	free (field);
+
+	p11_kit_modules_finalize_and_release (modules);
+	return ret;
+}
diff --git a/p11-kit/tests/test-conf.c b/p11-kit/tests/test-conf.c
index c214bac..3a94c12 100644
--- a/p11-kit/tests/test-conf.c
+++ b/p11-kit/tests/test-conf.c
@@ -46,6 +46,12 @@
 #include "p11-kit.h"
 #include "private.h"
 
+#ifdef OS_UNIX
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#endif
+
 static void
 test_parse_conf_1 (void)
 {
@@ -391,6 +397,36 @@ test_parse_boolean (void)
 	assert_num_eq (true, _p11_conf_parse_boolean ("!!!", true));
 }
 
+#ifdef OS_UNIX
+
+static void
+test_setuid (void)
+{
+	const char *args[] = { BUILDDIR "/frob-setuid", NULL, };
+	char *path;
+	int ret;
+
+	/* This is the 'number' setting set in one.module user configuration. */
+	ret = p11_test_run_child (args, true);
+	assert_num_eq (ret, 33);
+
+	path = p11_test_copy_setgid (args[0]);
+	if (path == NULL)
+		return;
+
+	args[0] = path;
+
+	/* This is the 'number' setting set in one.module system configuration. */
+	ret = p11_test_run_child (args, true);
+	assert_num_eq (ret, 18);
+
+	if (unlink (path) < 0)
+		assert_fail ("unlink failed", strerror (errno));
+	free (path);
+}
+
+#endif /* OS_UNIX */
+
 int
 main (int argc,
       char *argv[])
@@ -410,5 +446,8 @@ main (int argc,
 	p11_test (test_load_modules_user_only, "/conf/test_load_modules_user_only");
 	p11_test (test_load_modules_user_none, "/conf/test_load_modules_user_none");
 	p11_test (test_parse_boolean, "/conf/test_parse_boolean");
+#ifdef OS_UNIX
+	p11_test (test_setuid, "/conf/setuid");
+#endif
 	return p11_test_run (argc, argv);
 }