From: Arnaldo Carvalho de Melo <acme@kernel.org> To: Peter Zijlstra <peterz@infradead.org> Cc: Alexey Budankov <alexey.budankov@linux.intel.com>, Ravi Bangoria <ravi.bangoria@linux.ibm.com>, Alexei Starovoitov <ast@kernel.org>, Ingo Molnar <mingo@redhat.com>, James Morris <jmorris@namei.org>, Namhyung Kim <namhyung@kernel.org>, Serge Hallyn <serge@hallyn.com>, Jiri Olsa <jolsa@redhat.com>, Song Liu <songliubraving@fb.com>, Andi Kleen <ak@linux.intel.com>, Stephane Eranian <eranian@google.com>, Igor Lubashev <ilubashe@akamai.com>, Thomas Gleixner <tglx@linutronix.de>, linux-kernel <linux-kernel@vger.kernel.org>, "linux-security-module@vger.kernel.org" <linux-security-module@vger.kernel.org>, "selinux@vger.kernel.org" <selinux@vger.kernel.org>, "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>, linux-man@vger.kernel.org Subject: Re: [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Date: Tue, 14 Jul 2020 12:27:38 -0300 [thread overview] Message-ID: <20200714152738.GB43671@kernel.org> (raw) In-Reply-To: <20200714105934.GU10769@hirez.programming.kicks-ass.net> Em Tue, Jul 14, 2020 at 12:59:34PM +0200, Peter Zijlstra escreveu: > On Mon, Jul 13, 2020 at 03:51:52PM -0300, Arnaldo Carvalho de Melo wrote: > > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > > > index 856d98c36f56..a2397f724c10 100644 > > > > --- a/kernel/events/core.c > > > > +++ b/kernel/events/core.c > > > > @@ -11595,7 +11595,7 @@ SYSCALL_DEFINE5(perf_event_open, > > > > * perf_event_exit_task() that could imply). > > > > */ > > > > err = -EACCES; > > > > - if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) > > > > + if (!perfmon_capable() && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) > > > > goto err_cred; > > > > } > > > >> makes monitoring simpler and even more secure to use since Perf tool need > > > >> not to start/stop/single-step and read/write registers and memory and so on > > > >> like a debugger or strace-like tool. What do you think? > > > > I tend to agree, Peter? > So this basically says that if CAP_PERFMON, we don't care about the > ptrace() permissions? Just like how CAP_SYS_PTRACE would always allow > the ptrace checks? > I suppose that makes sense. Yeah, it in fact addresses the comment right above it: if (task) { err = mutex_lock_interruptible(&task->signal->exec_update_mutex); if (err) goto err_task; /* * Reuse ptrace permission checks for now. * * We must hold exec_update_mutex across this and any potential * perf_install_in_context() call for this new event to * serialize against exec() altering our credentials (and the * perf_event_exit_task() that could imply). */ err = -EACCES; if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) goto err_cred; } that "for now" part :-) Idea is to not require CAP_PTRACE for that, i.e. the attack surface for the perf binary is reduced. - Arnaldo
WARNING: multiple messages have this Message-ID (diff)
From: Arnaldo Carvalho de Melo <acme@kernel.org> To: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>, Song Liu <songliubraving@fb.com>, Andi Kleen <ak@linux.intel.com>, linux-man@vger.kernel.org, "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>, "selinux@vger.kernel.org" <selinux@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, Igor Lubashev <ilubashe@akamai.com>, Alexei Starovoitov <ast@kernel.org>, Stephane Eranian <eranian@google.com>, James Morris <jmorris@namei.org>, "linux-security-module@vger.kernel.org" <linux-security-module@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Jiri Olsa <jolsa@redhat.com>, "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, Serge Hallyn <serge@hallyn.com> Subject: Re: [Intel-gfx] [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Date: Tue, 14 Jul 2020 12:27:38 -0300 [thread overview] Message-ID: <20200714152738.GB43671@kernel.org> (raw) In-Reply-To: <20200714105934.GU10769@hirez.programming.kicks-ass.net> Em Tue, Jul 14, 2020 at 12:59:34PM +0200, Peter Zijlstra escreveu: > On Mon, Jul 13, 2020 at 03:51:52PM -0300, Arnaldo Carvalho de Melo wrote: > > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > > > index 856d98c36f56..a2397f724c10 100644 > > > > --- a/kernel/events/core.c > > > > +++ b/kernel/events/core.c > > > > @@ -11595,7 +11595,7 @@ SYSCALL_DEFINE5(perf_event_open, > > > > * perf_event_exit_task() that could imply). > > > > */ > > > > err = -EACCES; > > > > - if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) > > > > + if (!perfmon_capable() && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) > > > > goto err_cred; > > > > } > > > >> makes monitoring simpler and even more secure to use since Perf tool need > > > >> not to start/stop/single-step and read/write registers and memory and so on > > > >> like a debugger or strace-like tool. What do you think? > > > > I tend to agree, Peter? > So this basically says that if CAP_PERFMON, we don't care about the > ptrace() permissions? Just like how CAP_SYS_PTRACE would always allow > the ptrace checks? > I suppose that makes sense. Yeah, it in fact addresses the comment right above it: if (task) { err = mutex_lock_interruptible(&task->signal->exec_update_mutex); if (err) goto err_task; /* * Reuse ptrace permission checks for now. * * We must hold exec_update_mutex across this and any potential * perf_install_in_context() call for this new event to * serialize against exec() altering our credentials (and the * perf_event_exit_task() that could imply). */ err = -EACCES; if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) goto err_cred; } that "for now" part :-) Idea is to not require CAP_PTRACE for that, i.e. the attack surface for the perf binary is reduced. - Arnaldo _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2020-07-14 15:27 UTC|newest] Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-02 8:42 [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Alexey Budankov 2020-04-02 8:42 ` [Intel-gfx] " Alexey Budankov 2020-04-02 8:45 ` [PATCH v8 01/12] capabilities: introduce CAP_PERFMON to kernel and user space Alexey Budankov 2020-04-02 8:45 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] capabilities: Introduce " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:46 ` [PATCH v8 02/12] perf/core: open access to the core for CAP_PERFMON privileged process Alexey Budankov 2020-04-02 8:46 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] perf/core: Open " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:47 ` [PATCH v8 03/12] perf/core: open access to probes " Alexey Budankov 2020-04-02 8:47 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:47 ` [PATCH v8 04/12] perf tool: extend Perf tool with CAP_PERFMON capability support Alexey Budankov 2020-04-02 8:47 ` [Intel-gfx] " Alexey Budankov 2020-04-03 11:08 ` Jiri Olsa 2020-04-03 11:08 ` [Intel-gfx] " Jiri Olsa 2020-04-03 13:08 ` Alexey Budankov 2020-04-03 13:08 ` [Intel-gfx] " Alexey Budankov 2020-04-04 2:18 ` Namhyung Kim 2020-04-04 2:18 ` [Intel-gfx] " Namhyung Kim 2020-04-04 8:18 ` Alexey Budankov 2020-04-04 8:18 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] perf tools: Support CAP_PERFMON capability tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:48 ` [PATCH v8 05/12] drm/i915/perf: open access for CAP_PERFMON privileged process Alexey Budankov 2020-04-02 8:48 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] drm/i915/perf: Open " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:48 ` [PATCH v8 06/12] trace/bpf_trace: open " Alexey Budankov 2020-04-02 8:48 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] trace/bpf_trace: Open " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:49 ` [PATCH v8 07/12] powerpc/perf: open " Alexey Budankov 2020-04-02 8:49 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:50 ` [PATCH v8 08/12] parisc/perf: " Alexey Budankov 2020-04-02 8:50 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:51 ` [PATCH v8 09/12] drivers/perf: " Alexey Budankov 2020-04-02 8:51 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] drivers/perf: Open " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:53 ` [PATCH v8 10/12] drivers/oprofile: open " Alexey Budankov 2020-04-02 8:53 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] drivers/oprofile: Open " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:54 ` [PATCH v8 11/12] doc/admin-guide: update perf-security.rst with CAP_PERFMON information Alexey Budankov 2020-04-02 8:54 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] doc/admin-guide: Update " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 8:54 ` [PATCH v8 12/12] doc/admin-guide: update kernel.rst " Alexey Budankov 2020-04-02 8:54 ` [Intel-gfx] " Alexey Budankov 2020-04-05 14:10 ` Arnaldo Carvalho de Melo 2020-04-05 14:10 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-05 14:41 ` Alexey Budankov 2020-04-05 14:41 ` [Intel-gfx] " Alexey Budankov 2020-04-05 14:54 ` Alexey Budankov 2020-04-05 14:54 ` [Intel-gfx] " Alexey Budankov 2020-04-05 15:05 ` Arnaldo Carvalho de Melo 2020-04-05 15:05 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-05 15:51 ` Alexey Budankov 2020-04-05 15:51 ` [Intel-gfx] " Alexey Budankov 2020-04-22 12:17 ` [tip: perf/core] " tip-bot2 for Alexey Budankov 2020-04-22 12:17 ` [Intel-gfx] " tip-bot2 for Alexey Budankov 2020-04-02 9:37 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for Introduce CAP_PERFMON to secure system performance monitoring and observability (rev5) Patchwork 2020-04-02 10:02 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork 2020-04-03 11:24 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork 2020-04-05 16:00 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for Introduce CAP_PERFMON to secure system performance monitoring and observability (rev6) Patchwork 2020-04-07 14:30 ` [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Arnaldo Carvalho de Melo 2020-04-07 14:30 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 14:35 ` Arnaldo Carvalho de Melo 2020-04-07 14:35 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 14:54 ` Alexey Budankov 2020-04-07 14:54 ` [Intel-gfx] " Alexey Budankov 2020-04-07 16:36 ` Arnaldo Carvalho de Melo 2020-04-07 16:36 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 16:40 ` Arnaldo Carvalho de Melo 2020-04-07 16:40 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 17:17 ` Alexey Budankov 2020-04-07 17:17 ` [Intel-gfx] " Alexey Budankov 2020-04-07 16:52 ` Alexey Budankov 2020-04-07 16:52 ` [Intel-gfx] " Alexey Budankov 2020-04-07 17:02 ` Arnaldo Carvalho de Melo 2020-04-07 17:02 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 17:32 ` Alexey Budankov 2020-04-07 17:32 ` [Intel-gfx] " Alexey Budankov 2020-04-07 16:56 ` Arnaldo Carvalho de Melo 2020-04-07 16:56 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-07 17:23 ` Arnaldo Carvalho de Melo 2020-04-07 17:23 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-04-22 19:18 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for Introduce CAP_PERFMON to secure system performance monitoring and observability (rev18) Patchwork 2020-04-22 19:43 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork 2020-07-10 13:31 ` [PATCH v8 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Ravi Bangoria 2020-07-10 13:31 ` [Intel-gfx] " Ravi Bangoria 2020-07-10 14:30 ` Alexey Budankov 2020-07-10 14:30 ` [Intel-gfx] " Alexey Budankov 2020-07-10 17:09 ` Arnaldo Carvalho de Melo 2020-07-10 17:09 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-07-13 9:48 ` Alexey Budankov 2020-07-13 9:48 ` [Intel-gfx] " Alexey Budankov 2020-07-13 12:17 ` Arnaldo Carvalho de Melo 2020-07-13 12:17 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-07-13 12:37 ` Alexey Budankov 2020-07-13 12:37 ` [Intel-gfx] " Alexey Budankov 2020-07-13 18:51 ` Arnaldo Carvalho de Melo 2020-07-13 18:51 ` [Intel-gfx] " Arnaldo Carvalho de Melo 2020-07-14 10:59 ` Peter Zijlstra 2020-07-14 10:59 ` [Intel-gfx] " Peter Zijlstra 2020-07-14 15:27 ` Arnaldo Carvalho de Melo [this message] 2020-07-14 15:27 ` Arnaldo Carvalho de Melo 2020-07-21 13:06 ` Alexey Budankov 2020-07-21 13:06 ` [Intel-gfx] " Alexey Budankov 2020-07-22 11:30 ` Arnaldo Carvalho de Melo 2020-07-22 11:30 ` [Intel-gfx] " Arnaldo Carvalho de Melo
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