linux-kernel - Re: [PATCH] security: selinux: allow per-file labeling for bpffs

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Date:   Thu, 6 Feb 2020 12:35:07 -0500
From:   Stephen Smalley <sds@...ho.nsa.gov>
To:     Steven Moreland <smoreland@...gle.com>, paul@...l-moore.com,
        eparis@...isplace.org, keescook@...omium.org, anton@...msg.org,
        ccross@...roid.com, tony.luck@...el.com, selinux@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-team@...roid.com
Cc:     "Connor O'Brien" <connoro@...gle.com>
Subject: Re: [PATCH] security: selinux: allow per-file labeling for bpffs

On 2/6/20 12:21 PM, Stephen Smalley wrote:
> On 2/6/20 11:55 AM, Steven Moreland wrote:
>> From: Connor O'Brien <connoro@...gle.com>
>>
>> Add support for genfscon per-file labeling of bpffs files. This allows
>> for separate permissions for different pinned bpf objects, which may
>> be completely unrelated to each other.
> 
> Do you want bpf fs to also support userspace labeling of files via 
> setxattr()?  If so, you'll want to also add it to 
> selinux_is_genfs_special_handling() as well.
> 
> The only caveat I would note here is that it appears that bpf fs 
> supports rename, link, unlink, rmdir etc by userspace, which means that 
> name-based labeling via genfscon isn't necessarily safe/stable.  See
> https://github.com/SELinuxProject/selinux-kernel/issues/2
> 
>> Change-Id: I03ae28d3afea70acd6dc53ebf810b34b357b6eb5
> 
> Drop Change-Ids from patches submitted upstream please since they aren't 
> meaningful outside of Android.
> 
>> Signed-off-by: Connor O'Brien <connoro@...gle.com>
>> Signed-off-by: Steven Moreland <smoreland@...gle.com>
>> ---
>>   security/selinux/hooks.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index de4887742d7c..4f9396e6ce8c 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -872,6 +872,7 @@ static int selinux_set_mnt_opts(struct super_block 
>> *sb,
>>           !strcmp(sb->s_type->name, "sysfs") ||
>>           !strcmp(sb->s_type->name, "pstore") ||
>>           !strcmp(sb->s_type->name, "binder") ||
>> +        !strcmp(sb->s_type->name, "bpf") ||
>>           !strcmp(sb->s_type->name, "cgroup") ||
>>           !strcmp(sb->s_type->name, "cgroup2"))
>>           sbsec->flags |= SE_SBGENFS;
>>

Also, your patch appears to be based on an old kernel and won't apply 
upstream; see
https://github.com/SELinuxProject/selinux-kernel/blob/master/README.md