netdev - Re: [PATCH v2 net-next 0/3] bpf: share helpers between tracing and networking

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Date:	Mon, 15 Jun 2015 16:01:30 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	ast@...mgrid.com
Cc:	luto@...capital.net, mingo@...nel.org, rostedt@...dmis.org,
	wangnan0@...wei.com, lizefan@...wei.com,
	daniel.wagner@...-carit.de, daniel@...earbox.net,
	linux-api@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net-next 0/3] bpf: share helpers between tracing and
 networking

From: Alexei Starovoitov <ast@...mgrid.com>
Date: Fri, 12 Jun 2015 19:39:11 -0700

> v1->v2: switched to init_user_ns from current_user_ns as suggested by Andy
> 
> Introduce new helpers to access 'struct task_struct'->pid, tgid, uid, gid, comm
> fields in tracing and networking.
> 
> Share bpf_trace_printk() and bpf_get_smp_processor_id() helpers between
> tracing and networking.

Series applied, thanks.

Although I agree with the sentiment that this thing can cause
surprising results and can be asking for trouble.

If someone wants to filter traffic "by UID" they might make
a simple ingress TC ebpf program using these new interfaces
and expect it to work.

But the UID their program will see will be the UID of whatever
randomly happened to be executing when the packet was received
and processed.

So for these kinds of things such identifying markers are less
useful, and perhaps surprising in their results.
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