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From: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: David Laight <David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org>
Cc: 'Alexei Starovoitov'
	<ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>,
	Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
	Namhyung Kim <namhyung-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Arnaldo Carvalho de Melo
	<acme-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Jiri Olsa <jolsa-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Masami Hiramatsu
	<masami.hiramatsu.pt-FCd8Q96Dh0JBDgjK7y7TUQ@public.gmane.org>,
	"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
	Daniel Borkmann <daniel-FeC+5ew28dpmcu3hnIyYJQ@public.gmane.org>,
	Peter Zijlstra
	<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org>,
	"linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v10 tip 5/9] tracing: allow BPF programs to call bpf_trace_printk()
Date: Mon, 23 Mar 2015 13:07:53 +0100	[thread overview]
Message-ID: <20150323120753.GA22560@gmail.com> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D1CB07731-VkEWCZq2GCInGFn1LkZF6NBPR1lH4CV8@public.gmane.org>


* David Laight <David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org> wrote:

> From: Alexei Starovoitov
> > Debugging of BPF programs needs some form of printk from the program,
> > so let programs call limited trace_printk() with %d %u %x %p modifiers only.
> 
> Should anyone be allowed to use BPF programs to determine the kernel
> addresses of any items?
> Looks as though it is leaking kernel addresses to userspace.
> Note that the problem is with the arguments, not the format string.

All of these are privileged operations - inherent if you are trying to 
debug the kernel.

Thanks,

	Ingo

  parent reply	other threads:[~2015-03-23 12:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-22 19:39 [PATCH v10 tip 0/9] tracing: attach eBPF programs to kprobes Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 1/9] bpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs Alexei Starovoitov
     [not found] ` <1427053150-32213-1-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-22 19:39   ` [PATCH v10 tip 2/9] tracing: add kprobe flag Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 3/9] tracing: attach BPF programs to kprobes Alexei Starovoitov
2015-03-23  2:14   ` Masami Hiramatsu
2015-03-22 19:39 ` [PATCH v10 tip 4/9] tracing: allow BPF programs to call bpf_ktime_get_ns() Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 5/9] tracing: allow BPF programs to call bpf_trace_printk() Alexei Starovoitov
2015-03-23 11:37   ` David Laight
     [not found]     ` <063D6719AE5E284EB5DD2968C1650D6D1CB07731-VkEWCZq2GCInGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2015-03-23 12:07       ` Ingo Molnar [this message]
     [not found]         ` <20150323120753.GA22560-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-03-23 17:50           ` Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 6/9] samples: bpf: simple non-portable kprobe filter example Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 7/9] samples: bpf: counting example for kfree_skb and write syscall Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 8/9] samples: bpf: IO latency analysis (iosnoop/heatmap) Alexei Starovoitov
2015-03-22 19:39 ` [PATCH v10 tip 9/9] samples: bpf: kmem_alloc/free tracker Alexei Starovoitov

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