linux-kernel - Re: [PATCH bpf-next v5 8/9] bpf: Add tests for task_local

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Message-ID: <20201105232117.wxjt66r7okihgbcf@kafai-mbp.dhcp.thefacebook.com>
Date:   Thu, 5 Nov 2020 15:21:17 -0800
From:   Martin KaFai Lau <kafai@...com>
To:     KP Singh <kpsingh@...omium.org>
CC:     <linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Song Liu <songliubraving@...com>, Paul Turner <pjt@...gle.com>,
        Jann Horn <jannh@...gle.com>, Hao Luo <haoluo@...gle.com>
Subject: Re: [PATCH bpf-next v5 8/9] bpf: Add tests for task_local_storage

On Thu, Nov 05, 2020 at 10:58:26PM +0000, KP Singh wrote:
> From: KP Singh <kpsingh@...gle.com>
> 
> The test exercises the syscall based map operations by creating a pidfd
> for the current process.
> 
> For verifying kernel / LSM functionality, the test implements a simple
> MAC policy which denies an executable from unlinking itself. The LSM
> program bprm_committed_creds sets a task_local_storage with a pointer to
> the inode. This is then used to detect if the task is trying to unlink
> itself in the inode_unlink LSM hook.
> 
> The test copies /bin/rm to /tmp and executes it in a child thread with
> the intention of deleting itself. A successful test should prevent the
> the running executable from deleting itself.
> 
> The bpf programs are also updated to call bpf_spin_{lock, unlock} to
> trigger the verfier checks for spin locks.
> 
> The temporary file is cleaned up later in the test.
> 
> Signed-off-by: KP Singh <kpsingh@...gle.com>
Acked-by: Martin KaFai Lau <kafai@...com>