From 49eb7ab3b2b5a106307494d2a46248ecb1530578 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Thu, 17 Jan 2019 15:27:50 +0000 Subject: [PATCH] tools: bpftool: add basic probe capability, probe syscall availability Add a new component and command for bpftool, in order to probe the system to dump a set of eBPF-related parameters so that users can know what features are available on the system. Parameters are dumped in plain or JSON output (with -j/-p options). The current patch introduces probing of one simple parameter: availability of the bpf() system call. Later commits will add other probes. Sample output: # bpftool feature probe kernel Scanning system call availability... bpf() syscall is available # bpftool --json --pretty feature probe kernel { "syscall_config": { "have_bpf_syscall": true } } The optional "kernel" keyword enforces probing of the current system, which is the only possible behaviour at this stage. It can be safely omitted. The feature comes with the relevant man page, but bash completion will come in a dedicated commit. v3: - Do not probe kernel version. Contrarily to what is written below for v2, we can have the kernel version retrieved in libbpf instead of bpftool (in the patch adding probing for program types). v2: - Remove C-style macros output from this patch. - Even though kernel version is no longer needed for testing kprobes availability, note that we still collect it in this patch so that bpftool gets able to probe (in next patches) older kernels as well. Signed-off-by: Quentin Monnet Reviewed-by: Jakub Kicinski Reviewed-by: Stanislav Fomichev Signed-off-by: Alexei Starovoitov --- .../bpftool/Documentation/bpftool-cgroup.rst | 1 + .../bpftool/Documentation/bpftool-feature.rst | 60 ++++++++ .../bpf/bpftool/Documentation/bpftool-map.rst | 1 + .../bpf/bpftool/Documentation/bpftool-net.rst | 1 + .../bpftool/Documentation/bpftool-perf.rst | 1 + .../bpftool/Documentation/bpftool-prog.rst | 1 + tools/bpf/bpftool/Documentation/bpftool.rst | 1 + tools/bpf/bpftool/feature.c | 131 ++++++++++++++++++ tools/bpf/bpftool/main.c | 3 +- tools/bpf/bpftool/main.h | 1 + 10 files changed, 200 insertions(+), 1 deletion(-) create mode 100644 tools/bpf/bpftool/Documentation/bpftool-feature.rst create mode 100644 tools/bpf/bpftool/feature.c diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst index d07ccf8a23f7..d43fce568ef7 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst @@ -142,5 +142,6 @@ SEE ALSO **bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-map**\ (8), + **bpftool-feature**\ (8), **bpftool-net**\ (8), **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool-feature.rst b/tools/bpf/bpftool/Documentation/bpftool-feature.rst new file mode 100644 index 000000000000..40ac13c0b782 --- /dev/null +++ b/tools/bpf/bpftool/Documentation/bpftool-feature.rst @@ -0,0 +1,60 @@ +=============== +bpftool-feature +=============== +------------------------------------------------------------------------------- +tool for inspection of eBPF-related parameters for Linux kernel or net device +------------------------------------------------------------------------------- + +:Manual section: 8 + +SYNOPSIS +======== + + **bpftool** [*OPTIONS*] **feature** *COMMAND* + + *OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] } + + *COMMANDS* := { **probe** | **help** } + +MAP COMMANDS +============= + +| **bpftool** **feature probe** [**kernel**] +| **bpftool** **feature help** + +DESCRIPTION +=========== + **bpftool feature probe** [**kernel**] + Probe the running kernel and dump a number of eBPF-related + parameters, such as availability of the **bpf()** system call. + + Keyword **kernel** can be omitted. + + **bpftool feature help** + Print short help message. + +OPTIONS +======= + -h, --help + Print short generic help message (similar to **bpftool help**). + + -v, --version + Print version number (similar to **bpftool version**). + + -j, --json + Generate JSON output. For commands that cannot produce JSON, this + option has no effect. + + -p, --pretty + Generate human-readable JSON output. Implies **-j**. + +SEE ALSO +======== + **bpf**\ (2), + **bpf-helpers**\ (7), + **bpftool**\ (8), + **bpftool-prog**\ (8), + **bpftool-map**\ (8), + **bpftool-cgroup**\ (8), + **bpftool-net**\ (8), + **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst index 0584c31d3fe2..5c984ffc9f01 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-map.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst @@ -256,5 +256,6 @@ SEE ALSO **bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-cgroup**\ (8), + **bpftool-feature**\ (8), **bpftool-net**\ (8), **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool-net.rst b/tools/bpf/bpftool/Documentation/bpftool-net.rst index ed87c9b619ad..779dab3650ee 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-net.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-net.rst @@ -142,4 +142,5 @@ SEE ALSO **bpftool-prog**\ (8), **bpftool-map**\ (8), **bpftool-cgroup**\ (8), + **bpftool-feature**\ (8), **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool-perf.rst b/tools/bpf/bpftool/Documentation/bpftool-perf.rst index f4c5e5538bb8..bca5590a80d0 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-perf.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-perf.rst @@ -84,4 +84,5 @@ SEE ALSO **bpftool-prog**\ (8), **bpftool-map**\ (8), **bpftool-cgroup**\ (8), + **bpftool-feature**\ (8), **bpftool-net**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst index 58c8369b77dd..13b56102f528 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst @@ -258,5 +258,6 @@ SEE ALSO **bpftool**\ (8), **bpftool-map**\ (8), **bpftool-cgroup**\ (8), + **bpftool-feature**\ (8), **bpftool-net**\ (8), **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/Documentation/bpftool.rst b/tools/bpf/bpftool/Documentation/bpftool.rst index e1677e81ed59..27153bb816ac 100644 --- a/tools/bpf/bpftool/Documentation/bpftool.rst +++ b/tools/bpf/bpftool/Documentation/bpftool.rst @@ -72,5 +72,6 @@ SEE ALSO **bpftool-prog**\ (8), **bpftool-map**\ (8), **bpftool-cgroup**\ (8), + **bpftool-feature**\ (8), **bpftool-net**\ (8), **bpftool-perf**\ (8) diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c new file mode 100644 index 000000000000..954fb12a5228 --- /dev/null +++ b/tools/bpf/bpftool/feature.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +/* Copyright (c) 2019 Netronome Systems, Inc. */ + +#include +#include +#include +#include + +#include +#include + +#include + +#include "main.h" + +enum probe_component { + COMPONENT_UNSPEC, + COMPONENT_KERNEL, +}; + +/* Printing utility functions */ + +static void +print_bool_feature(const char *feat_name, const char *plain_name, bool res) +{ + if (json_output) + jsonw_bool_field(json_wtr, feat_name, res); + else + printf("%s is %savailable\n", plain_name, res ? "" : "NOT "); +} + +static void +print_start_section(const char *json_title, const char *plain_title) +{ + if (json_output) { + jsonw_name(json_wtr, json_title); + jsonw_start_object(json_wtr); + } else { + printf("%s\n", plain_title); + } +} + +/* Probing functions */ + +static bool probe_bpf_syscall(void) +{ + bool res; + + bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0); + res = (errno != ENOSYS); + + print_bool_feature("have_bpf_syscall", + "bpf() syscall", + res); + + return res; +} + +static int do_probe(int argc, char **argv) +{ + enum probe_component target = COMPONENT_UNSPEC; + + /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN). + * Let's approximate, and restrict usage to root user only. + */ + if (geteuid()) { + p_err("please run this command as root user"); + return -1; + } + + set_max_rlimit(); + + while (argc) { + if (is_prefix(*argv, "kernel")) { + if (target != COMPONENT_UNSPEC) { + p_err("component to probe already specified"); + return -1; + } + target = COMPONENT_KERNEL; + NEXT_ARG(); + } else { + p_err("expected no more arguments, 'kernel', got: '%s'?", + *argv); + return -1; + } + } + + if (json_output) + jsonw_start_object(json_wtr); + + print_start_section("syscall_config", + "Scanning system call availability..."); + + probe_bpf_syscall(); + + if (json_output) { + /* End current "section" of probes */ + jsonw_end_object(json_wtr); + /* End root object */ + jsonw_end_object(json_wtr); + } + + return 0; +} + +static int do_help(int argc, char **argv) +{ + if (json_output) { + jsonw_null(json_wtr); + return 0; + } + + fprintf(stderr, + "Usage: %s %s probe [kernel]\n" + " %s %s help\n" + "", + bin_name, argv[-2], bin_name, argv[-2]); + + return 0; +} + +static const struct cmd cmds[] = { + { "help", do_help }, + { "probe", do_probe }, + { 0 } +}; + +int do_feature(int argc, char **argv) +{ + return cmd_select(cmds, argc, argv, do_help); +} diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c index f44a1c2c4ea0..a9d5e9e6a732 100644 --- a/tools/bpf/bpftool/main.c +++ b/tools/bpf/bpftool/main.c @@ -56,7 +56,7 @@ static int do_help(int argc, char **argv) " %s batch file FILE\n" " %s version\n" "\n" - " OBJECT := { prog | map | cgroup | perf | net }\n" + " OBJECT := { prog | map | cgroup | perf | net | feature }\n" " " HELP_SPEC_OPTIONS "\n" "", bin_name, bin_name, bin_name); @@ -187,6 +187,7 @@ static const struct cmd cmds[] = { { "cgroup", do_cgroup }, { "perf", do_perf }, { "net", do_net }, + { "feature", do_feature }, { "version", do_version }, { 0 } }; diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h index 052c91d4dc55..5cfc6601de9b 100644 --- a/tools/bpf/bpftool/main.h +++ b/tools/bpf/bpftool/main.h @@ -145,6 +145,7 @@ int do_cgroup(int argc, char **arg); int do_perf(int argc, char **arg); int do_net(int argc, char **arg); int do_tracelog(int argc, char **arg); +int do_feature(int argc, char **argv); int parse_u32_arg(int *argc, char ***argv, __u32 *val, const char *what); int prog_parse_fd(int *argc, char ***argv); -- 2.30.2