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From: Ingo Molnar <mingo@kernel.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "'Alexei Starovoitov'" <ast@plumgrid.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Arnaldo Carvalho de Melo <acme@infradead.org>,
	Jiri Olsa <jolsa@redhat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	"David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.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@AcuExch.aculab.com>


* David Laight <David.Laight@ACULAB.COM> 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

  reply	other threads:[~2015-03-23 12:08 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
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
2015-03-23 12:07     ` Ingo Molnar [this message]
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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