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perf tool: Make perf tool aware of SELinux access control

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Implement selinux sysfs check to see the system is in enforcing mode and
print warning message with pointer to check audit logs.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/819338ce-d160-4a2f-f1aa-d756a2e7c6fc@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Alexey Budankov 2020-04-30 10:15:57 +03:00 committed by Arnaldo Carvalho de Melo
parent a885f3cc6f
commit c1034eb069
2 changed files with 26 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
tools/perf/util/cloexec.c
View File

@ -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;

37
tools/perf/util/evsel.c
View File

@ -2478,30 +2478,39 @@ int 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,
printed += scnprintf(msg, size,
"No permission to enable %s event.\n\n", 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 or CAP_SYS_ADMIN Linux capability.\n"
"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 " : "",
">= 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.", evsel__name(evsel));