Note I'm testing with the following patches: https://lore.kernel.org/bpf/20220706111839.1247911-1-james.hilliard1@xxxxxxxxx/ https://lore.kernel.org/bpf/20220706140623.2917858-1-james.hilliard1@xxxxxxxxx/ It would appear there's some compatibility issues with bpftool gen and GCC, not sure what side though is wrong here: /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool gen object src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o libbpf: failed to find BTF info for global/extern symbol 'sd_restrictif_i' Error: failed to link 'src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o': Unknown error -2 (-2) Relevant difference seems to be this: GCC: [55] FUNC 'sd_restrictif_i' type_id=47 linkage=static Clang: [27] FUNC 'sd_restrictif_i' type_id=26 linkage=global GCC: [1] INT 'signed char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN [2] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=CHAR [3] TYPEDEF '__u8' type_id=2 [4] CONST '(anon)' type_id=3 [5] VOLATILE '(anon)' type_id=4 [6] INT 'short int' size=2 bits_offset=0 nr_bits=16 encoding=SIGNED [7] INT 'short unsigned int' size=2 bits_offset=0 nr_bits=16 encoding=(none) [8] TYPEDEF '__u16' type_id=7 [9] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED [10] TYPEDEF '__s32' type_id=9 [11] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none) [12] TYPEDEF '__u32' type_id=11 [13] INT 'long long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED [14] INT 'long long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) [15] TYPEDEF '__u64' type_id=14 [16] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) [17] INT 'long int' size=8 bits_offset=0 nr_bits=64 encoding=SIGNED [18] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=UNKN [19] CONST '(anon)' type_id=18 [20] TYPEDEF '__be16' type_id=8 [21] TYPEDEF '__be32' type_id=12 [22] ENUM 'bpf_map_type' encoding=UNSIGNED size=4 vlen=31 'BPF_MAP_TYPE_UNSPEC' val=0 'BPF_MAP_TYPE_HASH' val=1 'BPF_MAP_TYPE_ARRAY' val=2 'BPF_MAP_TYPE_PROG_ARRAY' val=3 'BPF_MAP_TYPE_PERF_EVENT_ARRAY' val=4 'BPF_MAP_TYPE_PERCPU_HASH' val=5 'BPF_MAP_TYPE_PERCPU_ARRAY' val=6 'BPF_MAP_TYPE_STACK_TRACE' val=7 'BPF_MAP_TYPE_CGROUP_ARRAY' val=8 'BPF_MAP_TYPE_LRU_HASH' val=9 'BPF_MAP_TYPE_LRU_PERCPU_HASH' val=10 'BPF_MAP_TYPE_LPM_TRIE' val=11 'BPF_MAP_TYPE_ARRAY_OF_MAPS' val=12 'BPF_MAP_TYPE_HASH_OF_MAPS' val=13 'BPF_MAP_TYPE_DEVMAP' val=14 'BPF_MAP_TYPE_SOCKMAP' val=15 'BPF_MAP_TYPE_CPUMAP' val=16 'BPF_MAP_TYPE_XSKMAP' val=17 'BPF_MAP_TYPE_SOCKHASH' val=18 'BPF_MAP_TYPE_CGROUP_STORAGE' val=19 'BPF_MAP_TYPE_REUSEPORT_SOCKARRAY' val=20 'BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE' val=21 'BPF_MAP_TYPE_QUEUE' val=22 'BPF_MAP_TYPE_STACK' val=23 'BPF_MAP_TYPE_SK_STORAGE' val=24 'BPF_MAP_TYPE_DEVMAP_HASH' val=25 'BPF_MAP_TYPE_STRUCT_OPS' val=26 'BPF_MAP_TYPE_RINGBUF' val=27 'BPF_MAP_TYPE_INODE_STORAGE' val=28 'BPF_MAP_TYPE_TASK_STORAGE' val=29 'BPF_MAP_TYPE_BLOOM_FILTER' val=30 [23] UNION '(anon)' size=8 vlen=1 'flow_keys' type_id=29 bits_offset=0 [24] STRUCT 'bpf_flow_keys' size=56 vlen=13 'nhoff' type_id=8 bits_offset=0 'thoff' type_id=8 bits_offset=16 'addr_proto' type_id=8 bits_offset=32 'is_frag' type_id=3 bits_offset=48 'is_first_frag' type_id=3 bits_offset=56 'is_encap' type_id=3 bits_offset=64 'ip_proto' type_id=3 bits_offset=72 'n_proto' type_id=20 bits_offset=80 'sport' type_id=20 bits_offset=96 'dport' type_id=20 bits_offset=112 '(anon)' type_id=25 bits_offset=128 'flags' type_id=12 bits_offset=384 'flow_label' type_id=21 bits_offset=416 [25] UNION '(anon)' size=32 vlen=2 '(anon)' type_id=26 bits_offset=0 '(anon)' type_id=27 bits_offset=0 [26] STRUCT '(anon)' size=8 vlen=2 'ipv4_src' type_id=21 bits_offset=0 'ipv4_dst' type_id=21 bits_offset=32 [27] STRUCT '(anon)' size=32 vlen=2 'ipv6_src' type_id=28 bits_offset=0 'ipv6_dst' type_id=28 bits_offset=128 [28] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=4 [29] PTR '(anon)' type_id=24 [30] UNION '(anon)' size=8 vlen=1 'sk' type_id=32 bits_offset=0 [31] STRUCT 'bpf_sock' size=80 vlen=14 'bound_dev_if' type_id=12 bits_offset=0 'family' type_id=12 bits_offset=32 'type' type_id=12 bits_offset=64 'protocol' type_id=12 bits_offset=96 'mark' type_id=12 bits_offset=128 'priority' type_id=12 bits_offset=160 'src_ip4' type_id=12 bits_offset=192 'src_ip6' type_id=28 bits_offset=224 'src_port' type_id=12 bits_offset=352 'dst_port' type_id=20 bits_offset=384 'dst_ip4' type_id=12 bits_offset=416 'dst_ip6' type_id=28 bits_offset=448 'state' type_id=12 bits_offset=576 'rx_queue_mapping' type_id=10 bits_offset=608 [32] PTR '(anon)' type_id=31 [33] STRUCT '__sk_buff' size=192 vlen=33 'len' type_id=12 bits_offset=0 'pkt_type' type_id=12 bits_offset=32 'mark' type_id=12 bits_offset=64 'queue_mapping' type_id=12 bits_offset=96 'protocol' type_id=12 bits_offset=128 'vlan_present' type_id=12 bits_offset=160 'vlan_tci' type_id=12 bits_offset=192 'vlan_proto' type_id=12 bits_offset=224 'priority' type_id=12 bits_offset=256 'ingress_ifindex' type_id=12 bits_offset=288 'ifindex' type_id=12 bits_offset=320 'tc_index' type_id=12 bits_offset=352 'cb' type_id=34 bits_offset=384 'hash' type_id=12 bits_offset=544 'tc_classid' type_id=12 bits_offset=576 'data' type_id=12 bits_offset=608 'data_end' type_id=12 bits_offset=640 'napi_id' type_id=12 bits_offset=672 'family' type_id=12 bits_offset=704 'remote_ip4' type_id=12 bits_offset=736 'local_ip4' type_id=12 bits_offset=768 'remote_ip6' type_id=28 bits_offset=800 'local_ip6' type_id=28 bits_offset=928 'remote_port' type_id=12 bits_offset=1056 'local_port' type_id=12 bits_offset=1088 'data_meta' type_id=12 bits_offset=1120 '(anon)' type_id=23 bits_offset=1152 'tstamp' type_id=15 bits_offset=1216 'wire_len' type_id=12 bits_offset=1280 'gso_segs' type_id=12 bits_offset=1312 '(anon)' type_id=30 bits_offset=1344 'gso_size' type_id=12 bits_offset=1408 'hwtstamp' type_id=15 bits_offset=1472 [34] ARRAY '(anon)' type_id=12 index_type_id=16 nr_elems=5 [35] CONST '(anon)' type_id=33 [36] PTR '(anon)' type_id=0 [37] STRUCT '(anon)' size=24 vlen=3 'type' type_id=39 bits_offset=0 'key' type_id=40 bits_offset=64 'value' type_id=41 bits_offset=128 [38] ARRAY '(anon)' type_id=9 index_type_id=16 nr_elems=1 [39] PTR '(anon)' type_id=38 [40] PTR '(anon)' type_id=12 [41] PTR '(anon)' type_id=3 [42] ARRAY '(anon)' type_id=19 index_type_id=16 nr_elems=18 [43] CONST '(anon)' type_id=42 [44] FUNC_PROTO '(anon)' ret_type_id=36 vlen=2 '(anon)' type_id=36 '(anon)' type_id=46 [45] CONST '(anon)' type_id=0 [46] PTR '(anon)' type_id=45 [47] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 'sk' type_id=48 [48] PTR '(anon)' type_id=35 [49] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 'sk' type_id=48 [50] FUNC_PROTO '(anon)' ret_type_id=9 vlen=1 'sk' type_id=48 [51] VAR '_license' type_id=43, linkage=static [52] VAR 'sd_restrictif' type_id=37, linkage=global [53] VAR 'is_allow_list' type_id=5, linkage=global [54] FUNC 'bpf_map_lookup_elem' type_id=44 linkage=static [55] FUNC 'sd_restrictif_i' type_id=47 linkage=static [56] FUNC 'sd_restrictif_e' type_id=49 linkage=static [57] FUNC 'restrict_network_interfaces_impl' type_id=50 linkage=static [58] DATASEC 'license' size=0 vlen=1 type_id=51 offset=0 size=18 (VAR '_license') [59] DATASEC '.maps' size=0 vlen=1 type_id=52 offset=0 size=24 (VAR 'sd_restrictif') [60] DATASEC '.data' size=0 vlen=1 type_id=53 offset=0 size=1 (VAR 'is_allow_list') Clang: [1] PTR '(anon)' type_id=3 [2] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED [3] ARRAY '(anon)' type_id=2 index_type_id=4 nr_elems=1 [4] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none) [5] PTR '(anon)' type_id=6 [6] TYPEDEF '__u32' type_id=7 [7] INT 'unsigned int' size=4 bits_offset=0 nr_bits=32 encoding=(none) [8] PTR '(anon)' type_id=9 [9] TYPEDEF '__u8' type_id=10 [10] INT 'unsigned char' size=1 bits_offset=0 nr_bits=8 encoding=(none) [11] STRUCT '(anon)' size=24 vlen=3 'type' type_id=1 bits_offset=0 'key' type_id=5 bits_offset=64 'value' type_id=8 bits_offset=128 [12] VAR 'sd_restrictif' type_id=11, linkage=global [13] PTR '(anon)' type_id=14 [14] CONST '(anon)' type_id=15 [15] STRUCT '__sk_buff' size=192 vlen=33 'len' type_id=6 bits_offset=0 'pkt_type' type_id=6 bits_offset=32 'mark' type_id=6 bits_offset=64 'queue_mapping' type_id=6 bits_offset=96 'protocol' type_id=6 bits_offset=128 'vlan_present' type_id=6 bits_offset=160 'vlan_tci' type_id=6 bits_offset=192 'vlan_proto' type_id=6 bits_offset=224 'priority' type_id=6 bits_offset=256 'ingress_ifindex' type_id=6 bits_offset=288 'ifindex' type_id=6 bits_offset=320 'tc_index' type_id=6 bits_offset=352 'cb' type_id=16 bits_offset=384 'hash' type_id=6 bits_offset=544 'tc_classid' type_id=6 bits_offset=576 'data' type_id=6 bits_offset=608 'data_end' type_id=6 bits_offset=640 'napi_id' type_id=6 bits_offset=672 'family' type_id=6 bits_offset=704 'remote_ip4' type_id=6 bits_offset=736 'local_ip4' type_id=6 bits_offset=768 'remote_ip6' type_id=17 bits_offset=800 'local_ip6' type_id=17 bits_offset=928 'remote_port' type_id=6 bits_offset=1056 'local_port' type_id=6 bits_offset=1088 'data_meta' type_id=6 bits_offset=1120 '(anon)' type_id=18 bits_offset=1152 'tstamp' type_id=20 bits_offset=1216 'wire_len' type_id=6 bits_offset=1280 'gso_segs' type_id=6 bits_offset=1312 '(anon)' type_id=22 bits_offset=1344 'gso_size' type_id=6 bits_offset=1408 'hwtstamp' type_id=20 bits_offset=1472 [16] ARRAY '(anon)' type_id=6 index_type_id=4 nr_elems=5 [17] ARRAY '(anon)' type_id=6 index_type_id=4 nr_elems=4 [18] UNION '(anon)' size=8 vlen=1 'flow_keys' type_id=19 bits_offset=0 [19] PTR '(anon)' type_id=38 [20] TYPEDEF '__u64' type_id=21 [21] INT 'unsigned long long' size=8 bits_offset=0 nr_bits=64 encoding=(none) [22] UNION '(anon)' size=8 vlen=1 'sk' type_id=23 bits_offset=0 [23] PTR '(anon)' type_id=39 [24] FUNC_PROTO '(anon)' ret_type_id=2 vlen=1 'sk' type_id=13 [25] FUNC 'sd_restrictif_e' type_id=24 linkage=global [26] FUNC_PROTO '(anon)' ret_type_id=2 vlen=1 'sk' type_id=13 [27] FUNC 'sd_restrictif_i' type_id=26 linkage=global [28] CONST '(anon)' type_id=29 [29] VOLATILE '(anon)' type_id=9 [30] VAR 'is_allow_list' type_id=28, linkage=global [31] CONST '(anon)' type_id=32 [32] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED [33] ARRAY '(anon)' type_id=31 index_type_id=4 nr_elems=18 [34] VAR '_license' type_id=33, linkage=static [35] DATASEC '.maps' size=0 vlen=1 type_id=12 offset=0 size=24 (VAR 'sd_restrictif') [36] DATASEC '.rodata' size=0 vlen=1 type_id=30 offset=0 size=1 (VAR 'is_allow_list') [37] DATASEC 'license' size=0 vlen=1 type_id=34 offset=0 size=18 (VAR '_license') [38] FWD 'bpf_flow_keys' fwd_kind=struct [39] FWD 'bpf_sock' fwd_kind=struct
