linux-kernel - [PATCH 4.12 64/84] selftests/capabilities: Fix the test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 19 Jul 2017 11:44:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Naresh Kamboju <naresh.kamboju@...aro.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Kees Cook <keescook@...omium.org>,
        Shuah Khan <shuahkh@....samsung.com>, Greg KH <greg@...ah.com>,
        linux-kselftest@...r.kernel.org, Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 4.12 64/84] selftests/capabilities: Fix the test_execve test

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@...nel.org>

commit 796a3bae2fba6810427efdb314a1c126c9490fb3 upstream.

test_execve does rather odd mount manipulations to safely create
temporary setuid and setgid executables that aren't visible to the
rest of the system.  Those executables end up in the test's cwd, but
that cwd is MNT_DETACHed.

The core namespace code considers MNT_DETACHed trees to belong to no
mount namespace at all and, in general, MNT_DETACHed trees are only
barely function.  This interacted with commit 380cf5ba6b0a ("fs:
Treat foreign mounts as nosuid") to cause all MNT_DETACHed trees to
act as though they're nosuid, breaking the test.

Fix it by just not detaching the tree.  It's still in a private
mount namespace and is therefore still invisible to the rest of the
system (except via /proc, and the same nosuid logic will protect all
other programs on the system from believing in test_execve's setuid
bits).

While we're at it, fix some blatant whitespace problems.

Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
Fixes: 380cf5ba6b0a ("fs: Treat foreign mounts as nosuid")
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Shuah Khan <shuahkh@....samsung.com>
Cc: Greg KH <greg@...ah.com>
Cc: linux-kselftest@...r.kernel.org
Signed-off-by: Andy Lutomirski <luto@...nel.org>
Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 tools/testing/selftests/capabilities/test_execve.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

--- a/tools/testing/selftests/capabilities/test_execve.c
+++ b/tools/testing/selftests/capabilities/test_execve.c
@@ -138,9 +138,6 @@ static void chdir_to_tmpfs(void)

 	if (chdir(cwd) != 0)
 		err(1, "chdir to private tmpfs");
-
-	if (umount2(".", MNT_DETACH) != 0)
-		err(1, "detach private tmpfs");
 }

 static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
@@ -248,7 +245,7 @@ static int do_tests(int uid, const char
 			err(1, "chown");
 		if (chmod("validate_cap_sgidnonroot", S_ISGID | 0710) != 0)
 			err(1, "chmod");
-}
+	}

 	capng_get_caps_process();

@@ -384,7 +381,7 @@ static int do_tests(int uid, const char
 	} else {
 		printf("[RUN]\tNon-root +ia, sgidnonroot => i\n");
 		exec_other_validate_cap("./validate_cap_sgidnonroot",
-						false, false, true, false);
+					false, false, true, false);

 		if (fork_wait()) {
 			printf("[RUN]\tNon-root +ia, sgidroot => i\n");