Probes related to bpf_probe_write_user and bpf_trace_printk helpers emit dmesg warnings which might be confusing for people running bpftool on production environments. This change filters them out by default and introduces the new positional argument "full" which enables all available probes.

Signed-off-by: Michal Rostecki mrostecki@opensuse.org --- tools/bpf/bpftool/feature.c | 70 ++++++++++++++++++++++++++----------- 1 file changed, 49 insertions(+), 21 deletions(-)

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index 345e4a2b4f53..ada3e1502b45 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -513,14 +513,39 @@ probe_map_type(enum bpf_map_type map_type, const char *define_prefix, define_prefix); }

+static void +probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type, + const char *define_prefix, unsigned int id, + const char *ptype_name, __u32 ifindex) +{ + bool res; + + if (!supported_type) + res = false; + else + res = bpf_probe_helper(id, prog_type, ifindex); + + if (json_output) { + if (res) + jsonw_string(json_wtr, helper_name[id]); + } else if (define_prefix) { + printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n", + define_prefix, ptype_name, helper_name[id], + res ? "1" : "0"); + } else { + if (res) + printf("\n\t- %s", helper_name[id]); + } +} + static void probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type, - const char *define_prefix, __u32 ifindex) + const char *define_prefix, bool full_mode, + __u32 ifindex) { const char *ptype_name = prog_type_name[prog_type]; char feat_name[128]; unsigned int id; - bool res;

if (ifindex) /* Only test helpers for offload-able program types */ @@ -542,21 +567,19 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type, }

for (id = 1; id < ARRAY_SIZE(helper_name); id++) { - if (!supported_type) - res = false; - else - res = bpf_probe_helper(id, prog_type, ifindex); - - if (json_output) { - if (res) - jsonw_string(json_wtr, helper_name[id]); - } else if (define_prefix) { - printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n", - define_prefix, ptype_name, helper_name[id], - res ? "1" : "0"); - } else { - if (res) - printf("\n\t- %s", helper_name[id]); + /* Skip helper functions which emit dmesg messages when not in + * the full mode. + */ + switch (id) { + case 6: /* trace_printk */ + case 36: /* probe_write_user */ + if (!full_mode) + continue; + /* fallthrough */ + default: + probe_helper_for_progtype(prog_type, supported_type, + define_prefix, id, ptype_name, + ifindex); } }

@@ -655,7 +678,8 @@ static void section_map_types(const char *define_prefix, __u32 ifindex) }

static void -section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) +section_helpers(bool *supported_types, const char *define_prefix, + bool full_mode, __u32 ifindex) { unsigned int i;

@@ -681,7 +705,7 @@ section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) define_prefix); for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++) probe_helpers_for_progtype(i, supported_types[i], - define_prefix, ifindex); + define_prefix, full_mode, ifindex);

print_end_section(); } @@ -701,6 +725,7 @@ static int do_probe(int argc, char **argv) enum probe_component target = COMPONENT_UNSPEC; const char *define_prefix = NULL; bool supported_types[128] = {}; + bool full_mode = false; __u32 ifindex = 0; char *ifname;

@@ -740,6 +765,9 @@ static int do_probe(int argc, char **argv) strerror(errno)); return -1; } + } else if (is_prefix(*argv, "full")) { + full_mode = true; + NEXT_ARG(); } else if (is_prefix(*argv, "macros") && !define_prefix) { define_prefix = ""; NEXT_ARG(); @@ -775,7 +803,7 @@ static int do_probe(int argc, char **argv) goto exit_close_json; section_program_types(supported_types, define_prefix, ifindex); section_map_types(define_prefix, ifindex); - section_helpers(supported_types, define_prefix, ifindex); + section_helpers(supported_types, define_prefix, full_mode, ifindex); section_misc(define_prefix, ifindex);

exit_close_json: @@ -794,7 +822,7 @@ static int do_help(int argc, char **argv) }

fprintf(stderr, - "Usage: %s %s probe [COMPONENT] [macros [prefix PREFIX]]\n" + "Usage: %s %s probe [COMPONENT] [full] [macros [prefix PREFIX]]\n" " %s %s help\n" "\n" " COMPONENT := { kernel | dev NAME }\n"

Update documentation of "bpftool feature" command with information about new arguments: "full".

Signed-off-by: Michal Rostecki mrostecki@opensuse.org --- .../bpftool/Documentation/bpftool-feature.rst | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-feature.rst b/tools/bpf/bpftool/Documentation/bpftool-feature.rst index 4d08f35034a2..b04156cfd7a3 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-feature.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-feature.rst @@ -19,19 +19,24 @@ SYNOPSIS FEATURE COMMANDS ================

-| **bpftool** **feature probe** [*COMPONENT*] [**macros** [**prefix** *PREFIX*]] +| **bpftool** **feature probe** [*COMPONENT*] [**full**] [**macros** [**prefix** *PREFIX*]] | **bpftool** **feature help** | | *COMPONENT* := { **kernel** | **dev** *NAME* }

DESCRIPTION =========== - **bpftool feature probe** [**kernel**] [**macros** [**prefix** *PREFIX*]] + **bpftool feature probe** [**kernel**] [**full**] [**macros** [**prefix** *PREFIX*]] Probe the running kernel and dump a number of eBPF-related parameters, such as availability of the **bpf()** system call, JIT status, eBPF program types availability, eBPF helper functions availability, and more.

+ By default, bpftool **does not run probes** for + **bpf_probe_write_user**\ () and **bpf_trace_printk**() + helpers which print warnings to kernel logs. To enable them + and run all probes, the **full** keyword should be used. + If the **macros** keyword (but not the **-j** option) is passed, a subset of the output is dumped as a list of **#define** macros that are ready to be included in a C @@ -44,16 +49,12 @@ DESCRIPTION Keyword **kernel** can be omitted. If no probe target is specified, probing the kernel is the default behaviour.

- Note that when probed, some eBPF helpers (e.g. - **bpf_trace_printk**\ () or **bpf_probe_write_user**\ ()) may - print warnings to kernel logs. - - **bpftool feature probe dev** *NAME* [**macros** [**prefix** *PREFIX*]] + **bpftool feature probe dev** *NAME* [**full**] [**macros** [**prefix** *PREFIX*]] Probe network device for supported eBPF features and dump results to the console.

- The two keywords **macros** and **prefix** have the same - role as when probing the kernel. + The keywords **full**, **macros** and **prefix** have the + same role as when probing the kernel.

**bpftool feature help** Print short help message.

Add Python module with tests for "bpftool feature" command, which mainly wheck whether the "full" option is working properly.

Signed-off-by: Michal Rostecki mrostecki@opensuse.org --- tools/testing/selftests/.gitignore | 5 +- tools/testing/selftests/bpf/Makefile | 3 +- tools/testing/selftests/bpf/test_bpftool.py | 179 ++++++++++++++++++++ tools/testing/selftests/bpf/test_bpftool.sh | 5 + 4 files changed, 190 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/test_bpftool.py create mode 100755 tools/testing/selftests/bpf/test_bpftool.sh

diff --git a/tools/testing/selftests/.gitignore b/tools/testing/selftests/.gitignore index 61df01cdf0b2..304fdf1a21dc 100644 --- a/tools/testing/selftests/.gitignore +++ b/tools/testing/selftests/.gitignore @@ -3,4 +3,7 @@ gpiogpio-hammer gpioinclude/ gpiolsgpio tpm2/SpaceTest.log -tpm2/*.pyc + +# Python bytecode and cache +__pycache__/ +*.py[cod] diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 2a583196fa51..2dffce6cc429 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -62,7 +62,8 @@ TEST_PROGS := test_kmod.sh \ test_tc_tunnel.sh \ test_tc_edt.sh \ test_xdping.sh \ - test_bpftool_build.sh + test_bpftool_build.sh \ + test_bpftool.sh

TEST_PROGS_EXTENDED := with_addr.sh \ with_tunnels.sh \ diff --git a/tools/testing/selftests/bpf/test_bpftool.py b/tools/testing/selftests/bpf/test_bpftool.py new file mode 100644 index 000000000000..c8e54843a487 --- /dev/null +++ b/tools/testing/selftests/bpf/test_bpftool.py @@ -0,0 +1,179 @@ +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2020 SUSE LLC. + +import collections +import functools +import json +import os +import socket +import subprocess +import unittest + + +# Add the source tree of bpftool and /usr/local/sbin to PATH +cur_dir = os.path.dirname(os.path.realpath(__file__)) +bpftool_dir = os.path.abspath(os.path.join(cur_dir, "..", "..", "..", "..", + "tools", "bpf", "bpftool")) +os.environ["PATH"] = bpftool_dir + ":/usr/local/sbin:" + os.environ["PATH"] + + +class IfaceNotFoundError(Exception): + pass + + +class UnprivilegedUserError(Exception): + pass + + +def _bpftool(args, json=True): + _args = ["bpftool"] + if json: + _args.append("-j") + _args.extend(args) + + res = subprocess.run(_args, capture_output=True) + return res.stdout + + +def bpftool(args): + return _bpftool(args, json=False).decode("utf-8") + + +def bpftool_json(args): + res = _bpftool(args) + return json.loads(res) + + +def get_default_iface(): + for iface in socket.if_nameindex(): + if iface[1] != "lo": + return iface[1] + raise IfaceNotFoundError("Could not find any network interface to probe") + + +def default_iface(f): + @functools.wraps(f) + def wrapper(*args, **kwargs): + iface = get_default_iface() + return f(*args, iface, **kwargs) + return wrapper + + +class TestBpftool(unittest.TestCase): + @classmethod + def setUpClass(cls): + if os.getuid() != 0: + raise UnprivilegedUserError( + "This test suite needs root privileges") + + @default_iface + def test_feature_dev_json(self, iface): + unexpected_helpers = [ + "bpf_probe_write_user", + "bpf_trace_printk", + ] + expected_keys = [ + "syscall_config", + "program_types", + "map_types", + "helpers", + "misc", + ] + + res = bpftool_json(["feature", "probe", "dev", iface]) + # Check if the result has all expected keys. + self.assertCountEqual(res.keys(), expected_keys) + # Check if unexpected helpers are not included in helpers probes + # result. + for helpers in res["helpers"].values(): + for unexpected_helper in unexpected_helpers: + self.assertNotIn(unexpected_helper, helpers) + + def test_feature_kernel(self): + test_cases = [ + bpftool_json(["feature", "probe", "kernel"]), + bpftool_json(["feature", "probe"]), + bpftool_json(["feature"]), + ] + unexpected_helpers = [ + "bpf_probe_write_user", + "bpf_trace_printk", + ] + expected_keys = [ + "syscall_config", + "system_config", + "program_types", + "map_types", + "helpers", + "misc", + ] + + for tc in test_cases: + # Check if the result has all expected keys. + self.assertCountEqual(tc.keys(), expected_keys) + # Check if unexpected helpers are not included in helpers probes + # result. + for helpers in tc["helpers"].values(): + for unexpected_helper in unexpected_helpers: + self.assertNotIn(unexpected_helper, helpers) + + def test_feature_kernel_full(self): + test_cases = [ + bpftool_json(["feature", "probe", "kernel", "full"]), + bpftool_json(["feature", "probe", "full"]), + ] + expected_helpers = [ + "bpf_probe_write_user", + "bpf_trace_printk", + ] + + for tc in test_cases: + # Check if expected helpers are included at least once in any + # helpers list for any program type. Unfortunately we cannot assume + # that they will be included in all program types or a specific + # subset of programs. It depends on the kernel version and + # configuration. + found_helpers = False + + for helpers in tc["helpers"].values(): + if all(expected_helper in helpers + for expected_helper in expected_helpers): + found_helpers = True + break + + self.assertTrue(found_helpers) + + def test_feature_kernel_full_vs_not_full(self): + full_res = bpftool_json(["feature", "probe", "full"]) + not_full_res = bpftool_json(["feature", "probe"]) + not_full_set = set() + full_set = set() + + for helpers in full_res["helpers"].values(): + for helper in helpers: + full_set.add(helper) + + for helpers in not_full_res["helpers"].values(): + for helper in helpers: + not_full_set.add(helper) + + self.assertCountEqual(full_set - not_full_set, + {"bpf_probe_write_user", "bpf_trace_printk"}) + self.assertCountEqual(not_full_set - full_set, set()) + + def test_feature_macros(self): + expected_patterns = [ + r"/*** System call availability ***/", + r"#define HAVE_BPF_SYSCALL", + r"/*** eBPF program types ***/", + r"#define HAVE.*PROG_TYPE", + r"/*** eBPF map types ***/", + r"#define HAVE.*MAP_TYPE", + r"/*** eBPF helper functions ***/", + r"#define HAVE.*HELPER", + r"/*** eBPF misc features ***/", + ] + + res = bpftool(["feature", "probe", "macros"]) + for pattern in expected_patterns: + self.assertRegex(res, pattern) diff --git a/tools/testing/selftests/bpf/test_bpftool.sh b/tools/testing/selftests/bpf/test_bpftool.sh new file mode 100755 index 000000000000..66690778e36d --- /dev/null +++ b/tools/testing/selftests/bpf/test_bpftool.sh @@ -0,0 +1,5 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2020 SUSE LLC. + +python3 -m unittest -v test_bpftool.TestBpftool