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Subject[PATCH v3 1/4] perf: Add capability-related utilities
Date
Add utilities to help checking capabilities of the running procss.
Make perf link with libcap, if it is available. If no libcap-dev[el],
assume no capabilities.

Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
---
tools/build/Makefile.feature | 2 ++
tools/build/feature/Makefile | 4 ++++
tools/build/feature/test-libcap.c | 20 ++++++++++++++++++++
tools/perf/Makefile.config | 11 +++++++++++
tools/perf/Makefile.perf | 2 ++
tools/perf/util/Build | 2 ++
tools/perf/util/cap.c | 29 +++++++++++++++++++++++++++++
tools/perf/util/cap.h | 24 ++++++++++++++++++++++++
tools/perf/util/event.h | 1 +
tools/perf/util/python-ext-sources | 1 +
tools/perf/util/util.c | 9 +++++++++
11 files changed, 105 insertions(+)
create mode 100644 tools/build/feature/test-libcap.c
create mode 100644 tools/perf/util/cap.c
create mode 100644 tools/perf/util/cap.h

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 86b793dffbc4..8a19753cc26a 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -42,6 +42,7 @@ FEATURE_TESTS_BASIC := \
gtk2-infobar \
libaudit \
libbfd \
+ libcap \
libelf \
libelf-getphdrnum \
libelf-gelf_getnote \
@@ -110,6 +111,7 @@ FEATURE_DISPLAY ?= \
gtk2 \
libaudit \
libbfd \
+ libcap \
libelf \
libnuma \
numa_num_possible_cpus \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 0658b8cd0e53..8499385365c0 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -20,6 +20,7 @@ FILES= \
test-libbfd-liberty.bin \
test-libbfd-liberty-z.bin \
test-cplus-demangle.bin \
+ test-libcap.bin \
test-libelf.bin \
test-libelf-getphdrnum.bin \
test-libelf-gelf_getnote.bin \
@@ -105,6 +106,9 @@ $(OUTPUT)test-fortify-source.bin:
$(OUTPUT)test-bionic.bin:
$(BUILD)

+$(OUTPUT)test-libcap.bin:
+ $(BUILD) -lcap
+
$(OUTPUT)test-libelf.bin:
$(BUILD) -lelf

diff --git a/tools/build/feature/test-libcap.c b/tools/build/feature/test-libcap.c
new file mode 100644
index 000000000000..d2a2e152195f
--- /dev/null
+++ b/tools/build/feature/test-libcap.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/capability.h>
+#include <linux/capability.h>
+
+int main(void)
+{
+ cap_flag_value_t val;
+ cap_t caps = cap_get_proc();
+
+ if (!caps)
+ return 1;
+
+ if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &val) != 0)
+ return 1;
+
+ if (cap_free(caps) != 0)
+ return 1;
+
+ return 0;
+}
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index e4988f49ea79..9a06787fedc6 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -824,6 +824,17 @@ ifndef NO_LIBZSTD
endif
endif

+ifndef NO_LIBCAP
+ ifeq ($(feature-libcap), 1)
+ CFLAGS += -DHAVE_LIBCAP_SUPPORT
+ EXTLIBS += -lcap
+ $(call detected,CONFIG_LIBCAP)
+ else
+ msg := $(warning No libcap found, disables capability support, please install libcap-devel/libcap-dev);
+ NO_LIBCAP := 1
+ endif
+endif
+
ifndef NO_BACKTRACE
ifeq ($(feature-backtrace), 1)
CFLAGS += -DHAVE_BACKTRACE_SUPPORT
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 67512a12276b..f9807d8c005b 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -88,6 +88,8 @@ include ../scripts/utilities.mak
#
# Define NO_LIBBPF if you do not want BPF support
#
+# Define NO_LIBCAP if you do not want process capabilities considered by perf
+#
# Define NO_SDT if you do not want to define SDT event in perf tools,
# note that it doesn't disable SDT scanning support.
#
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..514b1f8992f6
--- /dev/null
+++ b/tools/perf/util/cap.h
@@ -0,0 +1,24 @@
+/* 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
+
+static inline bool perf_cap__capable(int cap __maybe_unused)
+{
+ return false;
+}
+
+#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/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)
{
--
2.7.4
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