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Date: Thu, 20 Dec 2018 12:24:27 +0000
From: Quentin Monnet <quentin.monnet@...ronome.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>
Cc: netdev@...r.kernel.org, oss-drivers@...ronome.com,
Quentin Monnet <quentin.monnet@...ronome.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Stanislav Fomichev <sdf@...gle.com>
Subject: [RFC PATCH bpf-next v2 4/9] tools: bpftool: add probes for eBPF program types
Introduce probes for supported BPF program types in libbpf, and call it
from bpftool to test what types are available on the system. The probe
simply consists in loading a very simple program of that type and see if
the verifier complains or not.
Sample output:
# bpftool feature probe kernel
...
Scanning eBPF program types...
eBPF program_type socket_filter is available
eBPF program_type kprobe is available
eBPF program_type sched_cls is available
...
# bpftool --json --pretty feature probe kernel
{
...
"program_types": {
"have_socket_filter_prog_type": true,
"have_kprobe_prog_type": true,
"have_sched_cls_prog_type": true,
...
}
}
v2:
- Move probes from bpftool to libbpf.
- Remove C-style macros output from this patch.
Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
tools/bpf/bpftool/feature.c | 53 +++++++++++++++++++++++++++++++--
tools/lib/bpf/Build | 2 +-
tools/lib/bpf/libbpf.h | 6 ++++
tools/lib/bpf/libbpf.map | 1 +
tools/lib/bpf/libbpf_probes.c | 55 +++++++++++++++++++++++++++++++++++
5 files changed, 114 insertions(+), 3 deletions(-)
create mode 100644 tools/lib/bpf/libbpf_probes.c
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index 238d7b80f426..3ba0a0a5904c 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (c) 2018 Netronome Systems, Inc. */
+#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
@@ -11,6 +12,7 @@
#include <linux/limits.h>
#include <bpf.h>
+#include <libbpf.h>
#include "main.h"
@@ -83,6 +85,17 @@ print_start_section(const char *json_title, const char *plain_title)
}
}
+static void
+print_end_then_start_section(const char *json_title, const char *plain_title)
+{
+ if (json_output)
+ jsonw_end_object(json_wtr);
+ else
+ printf("\n");
+
+ print_start_section(json_title, plain_title);
+}
+
/* Probing functions */
static int read_procfs(const char *path)
@@ -361,9 +374,36 @@ static bool probe_bpf_syscall(void)
return res;
}
+static void
+probe_prog_type(enum bpf_prog_type prog_type, int kernel_version,
+ bool *supported_types)
+{
+ const char *plain_comment = "eBPF program_type ";
+ char feat_name[128], plain_desc[128];
+ size_t maxlen;
+ bool res;
+
+ res = bpf_probe_prog_type(prog_type, kernel_version, 0);
+
+ supported_types[prog_type] |= res;
+
+ maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
+ if (strlen(prog_type_name[prog_type]) > maxlen) {
+ p_info("program type name too long");
+ return;
+ }
+
+ sprintf(feat_name, "have_%s_prog_type", prog_type_name[prog_type]);
+ sprintf(plain_desc, "%s%s", plain_comment, prog_type_name[prog_type]);
+ print_bool_feature(feat_name, plain_desc, res);
+}
+
static int do_probe(int argc, char **argv)
{
enum probe_component target = COMPONENT_UNSPEC;
+ bool supported_types[128] = {};
+ int kernel_version;
+ unsigned int i;
/* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN).
* Let's approximate, and restrict usage to root user only.
@@ -417,9 +457,18 @@ static int do_probe(int argc, char **argv)
print_start_section("syscall_config",
"Scanning system call and kernel version...");
- probe_kernel_version();
- probe_bpf_syscall();
+ kernel_version = probe_kernel_version();
+ if (!probe_bpf_syscall())
+ /* bpf() syscall unavailable, don't probe other BPF features */
+ goto exit_close_json;
+
+ print_end_then_start_section("program_types",
+ "Scanning eBPF program types...");
+
+ for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++)
+ probe_prog_type(i, kernel_version, supported_types);
+exit_close_json:
if (json_output) {
/* End current "section" of probes */
jsonw_end_object(json_wtr);
diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build
index 197b40f5b5c6..bfd9bfc82c3b 100644
--- a/tools/lib/bpf/Build
+++ b/tools/lib/bpf/Build
@@ -1 +1 @@
-libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o bpf_prog_linfo.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o bpf_prog_linfo.o libbpf_probes.o
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 5f68d7b75215..f4bb2764ca9a 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -355,6 +355,12 @@ LIBBPF_API const struct bpf_line_info *
bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
__u32 insn_off, __u32 nr_skip);
+/*
+ * Probe for supported system features
+ */
+LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
+ int kernel_version, __u32 ifindex);
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index cd02cd4e2cc3..6355e4c80a86 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -56,6 +56,7 @@ LIBBPF_0.0.1 {
bpf_object__unpin_maps;
bpf_object__unpin_programs;
bpf_perf_event_read_simple;
+ bpf_probe_prog_type;
bpf_prog_attach;
bpf_prog_detach;
bpf_prog_detach2;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
new file mode 100644
index 000000000000..2c5e0cdc9f2f
--- /dev/null
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/* Copyright (c) 2018 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <unistd.h>
+
+#include <linux/filter.h>
+#include <linux/kernel.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+
+static void
+prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
+ size_t insns_cnt, int kernel_version, char *buf, size_t buf_len,
+ __u32 ifindex)
+{
+ struct bpf_load_program_attr xattr = {};
+ int fd;
+
+ /* Some prog type require an expected_attach_type */
+ if (prog_type == BPF_PROG_TYPE_CGROUP_SOCK_ADDR)
+ xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
+
+ xattr.prog_type = prog_type;
+ xattr.insns = insns;
+ xattr.insns_cnt = insns_cnt;
+ xattr.license = "GPL";
+ xattr.kern_version = kernel_version;
+ xattr.prog_ifindex = ifindex;
+
+ fd = bpf_load_program_xattr(&xattr, buf, buf_len);
+ if (fd >= 0)
+ close(fd);
+}
+
+bool bpf_probe_prog_type(enum bpf_prog_type prog_type, int kernel_version,
+ __u32 ifindex)
+{
+ struct bpf_insn insns[2] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN()
+ };
+
+ if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
+ /* nfp returns -EINVAL on exit(0) with TC offload */
+ insns[0].imm = 2;
+
+ errno = 0;
+ prog_load(prog_type, insns, ARRAY_SIZE(insns), kernel_version,
+ NULL, 0, ifindex);
+
+ return errno != EINVAL && errno != EOPNOTSUPP;
+}
--
2.17.1
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