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Message-ID: <CALCETrVJYwoLT6=kQx9fRXzv7eVvC6dBiSHowjHHRrDCDFGJ1A@mail.gmail.com>
Date: Wed, 28 Jun 2017 14:21:01 -0700
From: Andy Lutomirski <luto@...nel.org>
To: Kees Cook <keescook@...omium.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Shuah Khan <shuahkh@....samsung.com>,
Andy Lutomirski <luto@...nel.org>, Greg KH <greg@...ah.com>,
Naresh Kamboju <naresh.kamboju@...aro.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Shuah Khan <shuah@...nel.org>
Subject: Re: selftests/capabilities: test FAIL on linux mainline and
linux-next and PASS on linux-4.4.70+
On Tue, Jun 27, 2017 at 9:35 PM, Kees Cook <keescook@...omium.org> wrote:
> On Tue, Jun 27, 2017 at 4:16 PM, Shuah Khan <shuahkh@....samsung.com> wrote:
>> On 06/27/2017 09:16 AM, Greg KH wrote:
>>> On Tue, Jun 27, 2017 at 05:13:59PM +0200, Greg KH wrote:
>>>> On Tue, Jun 27, 2017 at 02:10:32PM +0530, Naresh Kamboju wrote:
>>>>> selftest capabilities test failed on linux mainline and linux-next and
>>>>> PASS on linux-4.4.70+
>>>>
>>>> Odd. Any chance you can use 'git bisect' to track down the offending
>>>> commit?
>>>>
>>>> Does this also fail on x86 or any other platform you have available?
>>>> Let me go try this on my laptop...
>>>
>>> Ok, Linus's current tree (4.12.0-rc7+) also fails on this. I'm guessing
>>> it's failing, it's hard to understand the output. If only we had TAP
>>> output for this test :)
>>
>> As far as the output, it isn't bad. Not TAP13 will help make it better.
>> The problem seems to with the individual messages error/info. messages
>> themselves. This test has the quality of a developer unit test and the
>> messages could be improved for non-developer use.
>>
>> I ran the test on 4.11.8-rc1+ and 4.9.35-rc1 see the same failure.
>> It would be difficult to bisect this since it spans multiple releases.
>> I am hoping Andy can give us some insight.
>
> I bisected this to:
>
> commit 380cf5ba6b0a0b307f4afb62b186ca801defb203
> Author: Andy Lutomirski <luto@...capital.net>
> Date: Thu Jun 23 16:41:05 2016 -0500
>
> fs: Treat foreign mounts as nosuid
>
> I assume the test needs updating, but I bet Andy knows for sure. I can
> look into this more closely in the morning.
Hi Eric-
This is rather odd. The selftest
(tools/testing/selftests/capabilities/test_execve), run as root, fails
on current kernels. The failure is worked around by this:
diff --git a/tools/testing/selftests/capabilities/test_execve.c
b/tools/testing/selftests/capabilities/test_execve.c
index 10a21a958aaf..6db60889b211 100644
--- a/tools/testing/selftests/capabilities/test_execve.c
+++ b/tools/testing/selftests/capabilities/test_execve.c
@@ -139,8 +139,8 @@ 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");
+// if (umount2(".", MNT_DETACH) != 0)
+// err(1, "detach private tmpfs");
}
static void copy_fromat_to(int fromfd, const char *fromname, const
char *toname)
I think this is due to the line:
p->mnt_ns = NULL;
in umount_tree(). The test is putting us into a situation in which
our cwd has ->mnt_ns = NULL, which is making it act as if it's nosuid.
I can imagine this breaking some weird user code (like my test!). Is
it a real problem, though?
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