Commit 5ff05120 authored by Michal Rostecki's avatar Michal Rostecki Committed by Daniel Borkmann
Browse files

libbpf: Add probe for large INSN limit 

Introduce a new probe which checks whether kernel has large maximum
program size which was increased in the following commit:

c04c0d2b ("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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarMichal Rostecki <mrostecki@opensuse.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Link: https://lore.kernel.org/bpf/20200108162428.25014-2-mrostecki@opensuse.org
parent 1ece2fbe

tools/lib/bpf/libbpf.h

+1 −0
Original line number Diff line number Diff line
@@ -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

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -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;

tools/lib/bpf/libbpf_probes.c

+21 −0
Original line number Diff line number Diff line
@@ -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;

}

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