From: Peter Zijlstra <peterz@infradead.org>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
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Subject: Re: [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process
Date: Wed, 8 Jan 2020 17:07:13 +0100 [thread overview]
Message-ID: <20200108160713.GI2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c93309dc-b920-f5fa-f997-e8b2faf47b88@linux.intel.com>
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.
next prev parent reply other threads:[~2020-01-08 16:07 UTC|newest]
Thread overview: 15+ 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 [this message]
2020-01-09 11:36 ` 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
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
2019-12-18 9:31 ` [PATCH v4 9/9] drivers/oprofile: " Alexey Budankov
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