From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
"selinux@vger.kernel.org" <selinux@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>
Subject: [PATCH v2 3/4] perf tool: make Perf tool aware of SELinux access control
Date: Wed, 22 Apr 2020 17:45:34 +0300 [thread overview]
Message-ID: <7459371d-2ec8-4700-13b6-09b73998cc7c@linux.intel.com> (raw)
In-Reply-To: <66f2975b-4a69-b428-7dc5-d9aa40b3c673@linux.intel.com>
Implement SELinux sysfs check to see if the system is in enforcing
mode and print warning message with pointers to check audit logs.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
tools/perf/util/cloexec.c | 4 ++--
tools/perf/util/evsel.c | 40 +++++++++++++++++++++++----------------
2 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index a12872f2856a..9c8ec816261b 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -65,7 +65,7 @@ static int perf_flag_probe(void)
return 1;
}
- WARN_ONCE(err != EINVAL && err != EBUSY,
+ WARN_ONCE(err != EINVAL && err != EBUSY && err != EACCES,
"perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
err, str_error_r(err, sbuf, sizeof(sbuf)));
@@ -83,7 +83,7 @@ static int perf_flag_probe(void)
if (fd >= 0)
close(fd);
- if (WARN_ONCE(fd < 0 && err != EBUSY,
+ if (WARN_ONCE(fd < 0 && err != EBUSY && err != EACCES,
"perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
err, str_error_r(err, sbuf, sizeof(sbuf))))
return -1;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 9fa92649adb4..82492ca12405 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2514,32 +2514,40 @@ int perf_evsel__open_strerror(struct evsel *evsel, struct target *target,
int err, char *msg, size_t size)
{
char sbuf[STRERR_BUFSIZE];
- int printed = 0;
+ int printed = 0, enforced = 0;
switch (err) {
case EPERM:
case EACCES:
+ printed += scnprintf(msg + printed, size - printed,
+ "Access to performance monitoring and observability operations is limited.\n");
+
+ if (!sysfs__read_int("fs/selinux/enforce", &enforced)) {
+ if (enforced) {
+ printed += scnprintf(msg + printed, size - printed,
+ "Enforced MAC policy settings (SELinux) can limit access to performance\n"
+ "monitoring and observability operations. Inspect system audit records for\n"
+ "more perf_event access control information and adjusting the policy.\n");
+ }
+ }
+
if (err == EPERM)
- printed = scnprintf(msg, size,
- "No permission to enable %s event.\n\n",
+ printed += scnprintf(msg, size,
+ "No permission to enable %s event.\n",
perf_evsel__name(evsel));
return scnprintf(msg + printed, size - printed,
- "You may not have permission to collect %sstats.\n\n"
- "Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
- "which controls use of the performance events system by\n"
- "unprivileged users (without CAP_PERFMON or CAP_SYS_ADMIN).\n\n"
- "The current value is %d:\n\n"
+ "Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open\n"
+ "access to performance monitoring and observability operations for users\n"
+ "without CAP_PERFMON capability. perf_event_paranoid setting is %d:\n"
" -1: Allow use of (almost) all events by all users\n"
" Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK\n"
- ">= 0: Disallow ftrace function tracepoint by users without CAP_PERFMON or CAP_SYS_ADMIN\n"
- " Disallow raw tracepoint access by users without CAP_SYS_PERFMON or CAP_SYS_ADMIN\n"
- ">= 1: Disallow CPU event access by users without CAP_PERFMON or CAP_SYS_ADMIN\n"
- ">= 2: Disallow kernel profiling by users without CAP_PERFMON or CAP_SYS_ADMIN\n\n"
- "To make this setting permanent, edit /etc/sysctl.conf too, e.g.:\n\n"
- " kernel.perf_event_paranoid = -1\n" ,
- target->system_wide ? "system-wide " : "",
- perf_event_paranoid());
+ ">= 0: Disallow raw and ftrace function tracepoint access\n"
+ ">= 1: Disallow CPU event access\n"
+ ">= 2: Disallow kernel profiling\n"
+ "To make the adjusted perf_event_paranoid setting permanent preserve it\n"
+ "in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)",
+ perf_event_paranoid());
case ENOENT:
return scnprintf(msg, size, "The %s event is not supported.",
perf_evsel__name(evsel));
--
2.24.1
next prev parent reply other threads:[~2020-04-22 14:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 14:40 [PATCH v2 0/4] perf: make Perf tool aware of SELinux access control Alexey Budankov
2020-04-22 14:44 ` [PATCH v2 1/4] perf trace: substitute CAP_SYS_ADMIN with CAP_PERFMON in error message Alexey Budankov
2020-04-23 13:20 ` Arnaldo Carvalho de Melo
2020-04-23 14:49 ` Alexey Budankov
2020-04-23 18:10 ` Arnaldo Carvalho de Melo
2020-04-22 14:44 ` [PATCH v2 2/4] perf docs: substitute CAP_SYS_ADMIN with CAP_PERFMON where needed Alexey Budankov
2020-04-23 13:22 ` Arnaldo Carvalho de Melo
2020-04-23 14:51 ` Alexey Budankov
2020-04-22 14:45 ` Alexey Budankov [this message]
2020-04-23 13:27 ` [PATCH v2 3/4] perf tool: make Perf tool aware of SELinux access control Arnaldo Carvalho de Melo
2020-04-23 14:58 ` Alexey Budankov
2020-04-22 14:47 ` [PATCH v2 4/4] perf docs: introduce security.txt file to document related issues Alexey Budankov
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