linux-kernel - Re: [PATCH -next] selftests/landlock: Fix selftest ptrace

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Date:   Wed, 30 Nov 2022 20:32:41 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     limin <limin100@...wei.com>, Jeff Xu <jeffxu@...gle.com>
Cc:     hannes@...xchg.org, mhocko@...nel.org, roman.gushchin@...ux.dev,
        shakeelb@...gle.com, songmuchun@...edance.com, tj@...nel.org,
        lizefan.x@...edance.com, shuah@...nel.org,
        linux-kselftest@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Jorge Lucangeli Obes <jorgelo@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH -next] selftests/landlock: Fix selftest ptrace_test run
 fail

I checked and the Landlock ptrace test failed because Yama is enabled, 
which is expected. You can check that with 
/proc/sys/kernel/yama/ptrace_scope

Jeff Xu sent a patch to fix this case but it is not ready yet: 
https://lore.kernel.org/r/20220628222941.2642917-1-jeffxu@google.com

Could you please send a new patch Jeff, and add Limin in Cc?


On 29/11/2022 12:26, limin wrote:
> cat /proc/cmdline
> BOOT_IMAGE=/vmlinuz-6.1.0-next-20221116
> root=UUID=a65b3a79-dc02-4728-8a0c-5cf24f4ae08b ro
> systemd.unified_cgroup_hierarchy=1 cgroup_no_v1=all
> 
> 
> config
> 
> #
> # Automatically generated file; DO NOT EDIT.
> # Linux/x86 6.1.0-rc6 Kernel Configuration
> #

[...]

> CONFIG_SECURITY_YAMA=y

[...]

> CONFIG_LSM="landlock,lockdown,yama,integrity,apparmor"
[...]
> 
> On 2022/11/29 19:03, Mickaël Salaün wrote:
>> I tested with next-20221116 and all tests are OK. Could you share your
>> kernel configuration with a link? What is the content of /proc/cmdline?
>>
>> On 29/11/2022 02:42, limin wrote:
>>> I run test on Linux ubuntu2204 6.1.0-next-20221116
>>>
>>> I did't use yama.
>>>
>>> you can reproduce by this step:
>>>
>>> cd kernel_src
>>>
>>> cd tools/testing/selftests/landlock/
>>> make
>>> ./ptrace_test
>>>
>>>
>>>
>>>
>>> On 2022/11/29 3:44, Mickaël Salaün wrote:
>>>> This patch changes the test semantic and then cannot work on my test
>>>> environment. On which kernel did you run test? Do you use Yama or
>>>> something similar?
>>>>
>>>> On 28/11/2022 03:04, limin wrote:
>>>>> Tests PTRACE_ATTACH and PTRACE_MODE_READ on the parent,
>>>>> trace parent return -1 when child== 0
>>>>> How to reproduce warning:
>>>>> $ make -C tools/testing/selftests TARGETS=landlock run_tests
>>>>>
>>>>> Signed-off-by: limin <limin100@...wei.com>
>>>>> ---
>>>>>     tools/testing/selftests/landlock/ptrace_test.c | 5 ++---
>>>>>     1 file changed, 2 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/landlock/ptrace_test.c
>>>>> b/tools/testing/selftests/landlock/ptrace_test.c
>>>>> index c28ef98ff3ac..88c4dc63eea0 100644
>>>>> --- a/tools/testing/selftests/landlock/ptrace_test.c
>>>>> +++ b/tools/testing/selftests/landlock/ptrace_test.c
>>>>> @@ -267,12 +267,11 @@ TEST_F(hierarchy, trace)
>>>>>             /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the
>>>>> parent. */
>>>>>             err_proc_read = test_ptrace_read(parent);
>>>>>             ret = ptrace(PTRACE_ATTACH, parent, NULL, 0);
>>>>> +        EXPECT_EQ(-1, ret);
>>>>> +        EXPECT_EQ(EPERM, errno);
>>>>>             if (variant->domain_child) {
>>>>> -            EXPECT_EQ(-1, ret);
>>>>> -            EXPECT_EQ(EPERM, errno);
>>>>>                 EXPECT_EQ(EACCES, err_proc_read);
>>>>>             } else {
>>>>> -            EXPECT_EQ(0, ret);
>>>>>                 EXPECT_EQ(0, err_proc_read);
>>>>>             }
>>>>>             if (ret == 0) {