[PATCH bpf-next v3 1/2] libbpf: Add probe for large INSN limit
From: Michal Rostecki
Date: Wed Jan 08 2020 - 11:24:47 EST
Introduce a new probe which checks whether kernel has large maximum
program size (1M) which was increased in the following commit:
c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
Based on the similar check in Cilium[0], authored by Daniel Borkmann.
[0] https://github.com/cilium/cilium/commit/657d0f585afd26232cfa5d4e70b6f64d2ea91596
Co-authored-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Michal Rostecki <mrostecki@xxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf.map | 1 +
tools/lib/bpf/libbpf_probes.c | 21 +++++++++++++++++++++
3 files changed, 23 insertions(+)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index fe592ef48f1b..26bf539f1b3c 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -521,6 +521,7 @@ LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
LIBBPF_API bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex);
LIBBPF_API bool bpf_probe_helper(enum bpf_func_id id,
enum bpf_prog_type prog_type, __u32 ifindex);
+LIBBPF_API bool bpf_probe_large_insn_limit(__u32 ifindex);
/*
* Get bpf_prog_info in continuous memory
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index e9713a574243..b300d74c921a 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -219,6 +219,7 @@ LIBBPF_0.0.7 {
bpf_object__detach_skeleton;
bpf_object__load_skeleton;
bpf_object__open_skeleton;
+ bpf_probe_large_insn_limit;
bpf_prog_attach_xattr;
bpf_program__attach;
bpf_program__name;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index a9eb8b322671..221e6ad97012 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -321,3 +321,24 @@ bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
return res;
}
+
+/*
+ * Probe for availability of kernel commit (5.3):
+ *
+ * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
+ */
+bool bpf_probe_large_insn_limit(__u32 ifindex)
+{
+ struct bpf_insn insns[BPF_MAXINSNS + 1];
+ int i;
+
+ for (i = 0; i < BPF_MAXINSNS; i++)
+ insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
+ insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
+
+ errno = 0;
+ probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
+ ifindex);
+
+ return errno != E2BIG && errno != EINVAL;
+}
--
2.16.4