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

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Date:   Thu, 6 Feb 2020 12:21:18 -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 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;
>