From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Song Liu <songliubraving@fb.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"joonas.lahtinen@linux.intel.com"
<joonas.lahtinen@linux.intel.com>,
Will Deacon <will.deacon@arm.com>,
Alexei Starovoitov <ast@kernel.org>,
Stephane Eranian <eranian@google.com>,
"james.bottomley@hansenpartnership.com"
<james.bottomley@hansenpartnership.com>,
Paul Mackerras <paulus@samba.org>, Jiri Olsa <jolsa@redhat.com>,
Andi Kleen <ak@linux.intel.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Igor Lubashev <ilubashe@akamai.com>,
James Morris <jmorris@namei.org>, Ingo Molnar <mingo@redhat.com>,
oprofile-list@lists.sf.net, Serge Hallyn <serge@hallyn.com>,
Robert Richter <rric@kernel.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
"selinux@vger.kernel.org" <selinux@vger.ke>
Subject: Re: [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process
Date: Fri, 10 Jan 2020 19:41:41 +0300 [thread overview]
Message-ID: <dc943577-d3b0-5c76-e8dc-009b74aa5ced@linux.intel.com> (raw)
In-Reply-To: <20200110140234.GO2844@hirez.programming.kicks-ass.net>
On 10.01.2020 17:02, Peter Zijlstra wrote:
> On Thu, Jan 09, 2020 at 02:36:50PM +0300, Alexey Budankov wrote:
>> On 08.01.2020 19:07, Peter Zijlstra wrote:
>>> On Wed, Dec 18, 2019 at 12:25:35PM +0300, Alexey Budankov wrote:
>
>>>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>>>> index 059ee7116008..d9db414f2197 100644
>>>> --- a/kernel/events/core.c
>>>> +++ b/kernel/events/core.c
>>>> @@ -9056,7 +9056,7 @@ static int perf_kprobe_event_init(struct perf_event *event)
>>>> if (event->attr.type != perf_kprobe.type)
>>>> return -ENOENT;
>>>>
>>>> - if (!capable(CAP_SYS_ADMIN))
>>>> + if (!perfmon_capable())
>>>> return -EACCES;
>>>>
>>>> /*
>>>
>>> This one only allows attaching to already extant kprobes, right? It does
>>> not allow creation of kprobes.
>>
>> This unblocks creation of local trace kprobes and uprobes by CAP_SYS_PERFMON
>> privileged process, exactly the same as for CAP_SYS_ADMIN privileged process.
>
> I've no idea what you just said; it's just words.
>
> Again, this only allows attaching to previously created kprobes, it does
> not allow creating kprobes, right?
Not really, this allows creating a kprobe using perf_event_open syscall that
associates file descriptor with the kprobe [1].
Lifetime of that kprobe is equal to the lifetime of the file descriptor and
the kprobe is not visible in tracefs: /sys/kernel/debug/tracing/kprobe_events
>
> That is; I don't think CAP_SYS_PERFMON should be allowed to create
> kprobes.
>
> As might be clear; I don't actually know what the user-ABI is for
> creating kprobes.
~Alexey
---
[1] https://lore.kernel.org/lkml/20171206224518.3598254-1-songliubraving@fb.com/
next prev parent reply other threads:[~2020-01-10 16:41 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 9:16 [PATCH v4 0/7] Introduce CAP_SYS_PERFMON to secure system performance monitoring and observability Alexey Budankov
2019-12-18 9:24 ` [PATCH v4 1/9] capabilities: introduce CAP_SYS_PERFMON to kernel and user space Alexey Budankov
2019-12-18 19:56 ` Stephen Smalley
2019-12-28 3:53 ` Serge E. Hallyn
2020-01-13 20:25 ` Song Liu
2019-12-18 9:25 ` [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process Alexey Budankov
2020-01-08 16:07 ` Peter Zijlstra
2020-01-09 11:36 ` Alexey Budankov
2020-01-10 14:02 ` Peter Zijlstra
2020-01-10 15:52 ` Masami Hiramatsu
2020-01-10 16:45 ` Arnaldo Carvalho de Melo
2020-01-10 23:47 ` Masami Hiramatsu
2020-01-11 0:23 ` Song Liu
[not found] ` <5e191833.1c69fb81.8bc25.a88c@mx.google.com>
2020-01-12 1:44 ` Masami Hiramatsu
2020-01-10 16:41 ` Alexey Budankov [this message]
2020-01-10 17:34 ` Alexey Budankov
2019-12-18 9:26 ` [PATCH v4 3/9] perf tool: extend Perf tool with CAP_SYS_PERFMON capability support Alexey Budankov
2019-12-18 9:27 ` [PATCH v4 4/9] drm/i915/perf: open access for CAP_SYS_PERFMON privileged process Alexey Budankov
2019-12-19 9:10 ` Lionel Landwerlin
2019-12-18 9:28 ` [PATCH v4 5/9] trace/bpf_trace: " Alexey Budankov
2020-01-13 20:47 ` Song Liu
2019-12-18 9:28 ` [PATCH v4 6/9] powerpc/perf: " Alexey Budankov
2019-12-18 9:29 ` [PATCH v4 7/9] parisc/perf: " Alexey Budankov
2020-01-27 8:52 ` Helge Deller
2019-12-18 9:30 ` [PATCH v4 8/9] drivers/perf: " Alexey Budankov
2020-01-17 10:51 ` Will Deacon
2020-01-17 21:33 ` Alexey Budankov
2019-12-18 9:31 ` [PATCH v4 9/9] drivers/oprofile: " Alexey Budankov
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