* [PATCH 13/28] perf tools: Add helpers to use capabilities if present
[not found] <20190814184051.3125-1-acme@kernel.org>
@ 2019-08-14 18:40 ` Arnaldo Carvalho de Melo
2019-08-14 18:40 ` [PATCH 16/28] perf ftrace: Use CAP_SYS_ADMIN instead of euid==0 Arnaldo Carvalho de Melo
1 sibling, 0 replies; 2+ messages in thread
From: Arnaldo Carvalho de Melo @ 2019-08-14 18:40 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner
Cc: Arnaldo Carvalho de Melo, Mathieu Poirier, Suzuki Poulouse,
Clark Williams, Alexey Budankov, Igor Lubashev, linux-kernel,
James Morris, linux-perf-users, Alexander Shishkin,
Peter Zijlstra, Jiri Olsa, Namhyung Kim, linux-arm-kernel
From: Igor Lubashev <ilubashe@akamai.com>
Add utilities to help checking capabilities of the running procss. Make
perf link with libcap, if it is available. If no libcap-dev[el],
fallback to the geteuid() == 0 test used before.
Committer notes:
$ perf test python
18: 'import perf' in python : FAILED!
$ perf test -v python
Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
18: 'import perf' in python :
--- start ---
test child forked, pid 23288
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.so: undefined symbol: cap_get_flag
test child finished with -1
---- end ----
'import perf' in python: FAILED!
$
This happens because differently from the perf binary generated with
this patch applied:
$ ldd /tmp/build/perf/perf | grep libcap
libcap.so.2 => /lib64/libcap.so.2 (0x00007f724a4ef000)
$
The python binding isn't linking with libcap:
$ ldd /tmp/build/perf/python/perf.so | grep libcap
$
So add 'cap' to the 'extra_libraries' variable in
tools/perf/util/setup.py, and rebuild:
$ perf test python
18: 'import perf' in python : Ok
$
If we explicitely disable libcap it also continues to work:
$ make NO_LIBCAP=1 -C tools/perf O=/tmp/build/perf install-bin
$ ldd /tmp/build/perf/perf | grep libcap
$ ldd /tmp/build/perf/python/perf.so | grep libcap
$ perf test python
18: 'import perf' in python : Ok
$
Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
[ split from a larger patch ]
Link: http://lkml.kernel.org/r/8a1e76cf5c7c9796d0d4d240fbaa85305298aafa.1565188228.git.ilubashe@akamai.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/Build | 2 ++
tools/perf/util/cap.c | 29 +++++++++++++++++++++++++++++
tools/perf/util/cap.h | 27 +++++++++++++++++++++++++++
tools/perf/util/event.h | 1 +
tools/perf/util/python-ext-sources | 1 +
tools/perf/util/setup.py | 2 ++
tools/perf/util/util.c | 9 +++++++++
7 files changed, 71 insertions(+)
create mode 100644 tools/perf/util/cap.c
create mode 100644 tools/perf/util/cap.h
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 7abf05131889..7cda749059a9 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -148,6 +148,8 @@ perf-$(CONFIG_ZLIB) += zlib.o
perf-$(CONFIG_LZMA) += lzma.o
perf-$(CONFIG_ZSTD) += zstd.o
+perf-$(CONFIG_LIBCAP) += cap.o
+
perf-y += demangle-java.o
perf-y += demangle-rust.o
diff --git a/tools/perf/util/cap.c b/tools/perf/util/cap.c
new file mode 100644
index 000000000000..c3ba841bbf37
--- /dev/null
+++ b/tools/perf/util/cap.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Capability utilities
+ */
+
+#ifdef HAVE_LIBCAP_SUPPORT
+
+#include "cap.h"
+#include <stdbool.h>
+#include <sys/capability.h>
+
+bool perf_cap__capable(cap_value_t cap)
+{
+ cap_flag_value_t val;
+ cap_t caps = cap_get_proc();
+
+ if (!caps)
+ return false;
+
+ if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val) != 0)
+ val = CAP_CLEAR;
+
+ if (cap_free(caps) != 0)
+ return false;
+
+ return val == CAP_SET;
+}
+
+#endif /* HAVE_LIBCAP_SUPPORT */
diff --git a/tools/perf/util/cap.h b/tools/perf/util/cap.h
new file mode 100644
index 000000000000..10af94e473da
--- /dev/null
+++ b/tools/perf/util/cap.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_CAP_H
+#define __PERF_CAP_H
+
+#include <stdbool.h>
+#include <linux/capability.h>
+#include <linux/compiler.h>
+
+#ifdef HAVE_LIBCAP_SUPPORT
+
+#include <sys/capability.h>
+
+bool perf_cap__capable(cap_value_t cap);
+
+#else
+
+#include <unistd.h>
+#include <sys/types.h>
+
+static inline bool perf_cap__capable(int cap __maybe_unused)
+{
+ return geteuid() == 0;
+}
+
+#endif /* HAVE_LIBCAP_SUPPORT */
+
+#endif /* __PERF_CAP_H */
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 70841d115349..0e164e8ae28d 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -851,6 +851,7 @@ void cpu_map_data__synthesize(struct cpu_map_data *data, struct perf_cpu_map *m
void event_attr_init(struct perf_event_attr *attr);
int perf_event_paranoid(void);
+bool perf_event_paranoid_check(int max_level);
extern int sysctl_perf_event_max_stack;
extern int sysctl_perf_event_max_contexts_per_stack;
diff --git a/tools/perf/util/python-ext-sources b/tools/perf/util/python-ext-sources
index 235bd9803390..c6dd478956f1 100644
--- a/tools/perf/util/python-ext-sources
+++ b/tools/perf/util/python-ext-sources
@@ -7,6 +7,7 @@
util/python.c
../lib/ctype.c
+util/cap.c
util/evlist.c
util/evsel.c
util/cpumap.c
diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index d48f9cd58964..aa344a163eaf 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -59,6 +59,8 @@ ext_sources = list(map(lambda x: '%s/%s' % (src_perf, x) , ext_sources))
extra_libraries = []
if '-DHAVE_LIBNUMA_SUPPORT' in cflags:
extra_libraries = [ 'numa' ]
+if '-DHAVE_LIBCAP_SUPPORT' in cflags:
+ extra_libraries += [ 'cap' ]
perf = Extension('perf',
sources = ext_sources,
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9c3c97697387..6fd130a5d8f2 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -16,10 +16,12 @@
#include <string.h>
#include <errno.h>
#include <limits.h>
+#include <linux/capability.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/time64.h>
#include <unistd.h>
+#include "cap.h"
#include "strlist.h"
#include "string2.h"
@@ -403,6 +405,13 @@ int perf_event_paranoid(void)
return value;
}
+
+bool perf_event_paranoid_check(int max_level)
+{
+ return perf_cap__capable(CAP_SYS_ADMIN) ||
+ perf_event_paranoid() <= max_level;
+}
+
static int
fetch_ubuntu_kernel_version(unsigned int *puint)
{
--
2.21.0
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^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH 16/28] perf ftrace: Use CAP_SYS_ADMIN instead of euid==0
[not found] <20190814184051.3125-1-acme@kernel.org>
2019-08-14 18:40 ` [PATCH 13/28] perf tools: Add helpers to use capabilities if present Arnaldo Carvalho de Melo
@ 2019-08-14 18:40 ` Arnaldo Carvalho de Melo
1 sibling, 0 replies; 2+ messages in thread
From: Arnaldo Carvalho de Melo @ 2019-08-14 18:40 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner
Cc: Arnaldo Carvalho de Melo, Mathieu Poirier, Suzuki Poulouse,
Clark Williams, Alexey Budankov, Igor Lubashev, linux-kernel,
James Morris, linux-perf-users, Alexander Shishkin,
Peter Zijlstra, Jiri Olsa, Namhyung Kim, linux-arm-kernel
From: Igor Lubashev <ilubashe@akamai.com>
The kernel requires CAP_SYS_ADMIN instead of euid==0 to mount debugfs
for ftrace. Make perf do the same.
Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/bd8763b72ed4d58d0b42d44fbc7eb474d32e53a3.1565188228.git.ilubashe@akamai.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-ftrace.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 20d4c0ce8b53..01a5bb58eb04 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -13,6 +13,7 @@
#include <signal.h>
#include <fcntl.h>
#include <poll.h>
+#include <linux/capability.h>
#include "debug.h"
#include <subcmd/parse-options.h>
@@ -21,6 +22,7 @@
#include "target.h"
#include "cpumap.h"
#include "thread_map.h"
+#include "util/cap.h"
#include "util/config.h"
@@ -281,7 +283,7 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
.events = POLLIN,
};
- if (geteuid() != 0) {
+ if (!perf_cap__capable(CAP_SYS_ADMIN)) {
pr_err("ftrace only works for root!\n");
return -1;
}
--
2.21.0
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^ permalink raw reply related [flat|nested] 2+ messages in thread