linux-kernel - Re: [PATCH] selinux: Fix SBLABEL

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Date:   Thu, 30 Mar 2017 09:49:07 +0200
From:   Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:     "J. Bruce Fields" <bfields@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>,
        James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>, selinux@...ho.nsa.gov,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH] selinux: Fix SBLABEL_MNT for NFS mounts

On 29 March 2017 at 23:34, J. Bruce Fields <bfields@...hat.com> wrote:
> On Wed, Mar 29, 2017 at 05:27:23PM +0200, Tomeu Vizoso wrote:
>> Labelling of files in a NFSv4.2 currently fails with ENOTSUPP because
>> the mount point doesn't have SBLABEL_MNT.
>>
>> Add specific condition for NFS4 filesystems so it gets correctly
>> labeled.
>
> Huh.  Looking at the code, I think this is meant to be handled by the
> SECURITY_FS_USE_NATIVE case--there was a similar failure fixed some time
> ago by 9fc2b4b436cf.  What kernel are you seeing this on?  Is it a
> recent regression (in which case, what's the latest kernel that worked
> for you)?

I have seen this on 4.11-rc4, but I never tried to get this working before.

I will try to find time to see why SECURITY_FS_USE_NATIVE isn't working here.

Thanks,

Tomeu

> --b.
>
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
>> Cc: J. Bruce Fields <bfields@...hat.com>
>>
>> ---
>>
>> Hi,
>>
>> cannot remotely say that I currently understand how selinux is expected
>> to work within NFS mounts, but this change allowed me to fully boot AOSP
>> with its rootfs and ramdisk on a single NFS share.
>>
>> Thanks,
>>
>> Tomeu
>> ---
>>  security/selinux/hooks.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index 0c2ac318aa7f..71cd1d8c67c2 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -485,6 +485,7 @@ static int selinux_is_sblabel_mnt(struct super_block *sb)
>>               !strcmp(sb->s_type->name, "debugfs") ||
>>               !strcmp(sb->s_type->name, "tracefs") ||
>>               !strcmp(sb->s_type->name, "rootfs") ||
>> +             !strcmp(sb->s_type->name, "nfs4") ||
>>               (selinux_policycap_cgroupseclabel &&
>>                (!strcmp(sb->s_type->name, "cgroup") ||
>>                 !strcmp(sb->s_type->name, "cgroup2")));
>> --
>> 2.9.3
>>