From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>, James Morris <jmorris@namei.org>,
Jiri Olsa <jolsa@redhat.com>, Andi Kleen <ak@linux.intel.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process
Date: Fri, 3 Apr 2020 17:28:59 +0300 [thread overview]
Message-ID: <930384c0-e852-a7bf-cd61-829cb9993234@linux.intel.com> (raw)
In-Reply-To: <4e528ce4-a937-358b-47b6-7d7085ab4eaa@linux.intel.com>
On 01.04.2020 23:49, Alexey Budankov wrote:
> Hi Peter,
>
> On 08.01.2020 19:07, Peter Zijlstra wrote:
>> On Wed, Dec 18, 2019 at 12:25:35PM +0300, Alexey Budankov wrote:
>>>
>>> Open access to perf_events monitoring for CAP_SYS_PERFMON privileged
>>> processes. For backward compatibility reasons access to perf_events
>>> subsystem remains open for CAP_SYS_ADMIN privileged processes but
>>> CAP_SYS_ADMIN usage for secure perf_events monitoring is discouraged
>>> with respect to CAP_SYS_PERFMON capability.
>>>
>>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
>>> ---
>>> include/linux/perf_event.h | 6 +++---
>>> kernel/events/core.c | 6 +++---
>>> 2 files changed, 6 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
>>> index 34c7c6910026..f46acd69425f 100644
>>> --- a/include/linux/perf_event.h
>>> +++ b/include/linux/perf_event.h
>>> @@ -1285,7 +1285,7 @@ static inline int perf_is_paranoid(void)
>>>
>>> static inline int perf_allow_kernel(struct perf_event_attr *attr)
>>> {
>>> - if (sysctl_perf_event_paranoid > 1 && !capable(CAP_SYS_ADMIN))
>>> + if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
>>> return -EACCES;
>>>
>>> return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
>>> @@ -1293,7 +1293,7 @@ static inline int perf_allow_kernel(struct perf_event_attr *attr)
>>>
>>> static inline int perf_allow_cpu(struct perf_event_attr *attr)
>>> {
>>> - if (sysctl_perf_event_paranoid > 0 && !capable(CAP_SYS_ADMIN))
>>> + if (sysctl_perf_event_paranoid > 0 && !perfmon_capable())
>>> return -EACCES;
>>>
>>> return security_perf_event_open(attr, PERF_SECURITY_CPU);
>>> @@ -1301,7 +1301,7 @@ static inline int perf_allow_cpu(struct perf_event_attr *attr)
>>>
>>> static inline int perf_allow_tracepoint(struct perf_event_attr *attr)
>>> {
>>> - if (sysctl_perf_event_paranoid > -1 && !capable(CAP_SYS_ADMIN))
>>> + if (sysctl_perf_event_paranoid > -1 && !perfmon_capable())
>>> return -EPERM;
>>>
>>> return security_perf_event_open(attr, PERF_SECURITY_TRACEPOINT);
>>
>> These are OK I suppose.
>>
>>> 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.
>>
>>> @@ -9116,7 +9116,7 @@ static int perf_uprobe_event_init(struct perf_event *event)
>>> if (event->attr.type != perf_uprobe.type)
>>> return -ENOENT;
>>>
>>> - if (!capable(CAP_SYS_ADMIN))
>>> + if (!perfmon_capable())
>>> return -EACCES;
>>>
>>> /*
>>
>> Idem, I presume.
>>
>>> @@ -11157,7 +11157,7 @@ SYSCALL_DEFINE5(perf_event_open,
>>> }
>>>
>>> if (attr.namespaces) {
>>> - if (!capable(CAP_SYS_ADMIN))
>>> + if (!perfmon_capable())
>>> return -EACCES;
>>> }
>>
>> And given we basically make the entire kernel observable with this CAP,
>> busting namespaces shoulnd't be a problem either.
>>
>> So yeah, I suppose that works.
>
> Could this have you explicit Reviewed-by or Acked-by tag
> so the changes could be driven into the kernel?
> Latest v7 is here:
> https://lore.kernel.org/lkml/c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com/
Posted v8 with all acquired tags so far:
https://lore.kernel.org/lkml/f96f8f8a-e65c-3f36-dc85-fc3f5191e8c5@linux.intel.com/
Thanks,
Alexey
next prev parent reply other threads:[~2020-04-03 14:29 UTC|newest]
Thread overview: 33+ 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
2019-12-18 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
[not found] ` <20200110140234.GO2844@hirez.programming.kicks-ass.net>
[not found] ` <20200111005213.6dfd98fb36ace098004bde0e@kernel.org>
[not found] ` <20200110164531.GA2598@kernel.org>
[not found] ` <20200111084735.0ff01c758bfbfd0ae2e1f24e@kernel.org>
[not found] ` <2B79131A-3F76-47F5-AAB4-08BCA820473F@fb.com>
[not found] ` <5e191833.1c69fb81.8bc25.a88c@mx.google.com>
2020-01-11 9:57 ` Alexey Budankov
2020-01-13 20:39 ` Song Liu
2020-01-14 3:25 ` Masami Hiramatsu
2020-01-14 5:17 ` Alexei Starovoitov
2020-01-14 9:47 ` Alexey Budankov
2020-01-14 18:06 ` Alexei Starovoitov
2020-01-14 18:50 ` Alexey Budankov
2020-01-15 1:52 ` Alexei Starovoitov
2020-01-15 5:15 ` Alexey Budankov
2020-04-01 20:50 ` Alexey Budankov
2020-04-03 13:55 ` Alexey Budankov
2020-04-03 13:56 ` Alexey Budankov
2020-01-15 9:45 ` Masami Hiramatsu
2020-01-15 12:11 ` Alexey Budankov
2020-01-14 12:04 ` Masami Hiramatsu
2020-04-01 20:49 ` Alexey Budankov
2020-04-03 14:28 ` Alexey Budankov [this message]
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
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
[not found] ` <20200117105153.GB6144@willie-the-truck>
2020-01-18 18:48 ` Alexey Budankov
2019-12-18 9:31 ` [PATCH v4 9/9] drivers/oprofile: " Alexey Budankov
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