On Sat, Jul 9, 2022 at 2:32 PM James Hilliard <james.hilliard1@xxxxxxxxx> wrote: > > On Sat, Jul 9, 2022 at 2:21 PM Jose E. Marchesi > <jose.marchesi@xxxxxxxxxx> wrote: > > > > > > > On Sat, Jul 9, 2022 at 11:24 AM Jose E. Marchesi > > > <jose.marchesi@xxxxxxxxxx> wrote: > > >> > > >> > > >> > On Fri, Jul 8, 2022 at 12:33 PM Jose E. Marchesi > > >> > <jose.marchesi@xxxxxxxxxx> wrote: > > >> >> > > >> >> > > >> >> >> On Wed, Jul 6, 2022 at 10:13 AM James Hilliard > > >> >> >> <james.hilliard1@xxxxxxxxx> wrote: > > >> >> >>> > > >> >> >>> 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 > > >> >> > > > >> >> > For functions GCC generates a BTF_KIND_FUNC entry, which has no linkage > > >> >> > information, or so we thought: I just looked at bpftool/btf.c and I > > >> >> > found the linkage info for function types is expected to be encoded in > > >> >> > the vlen field of BTF_KIND_FUNC entries (why not adding a btf_func > > >> >> > instead???) which is surprising to say the least. > > >> >> > > > >> >> > We are changing GCC to encode the linkage info in vlen for these types. > > >> >> > Thanks for reporting this. > > >> >> > > >> >> Patch sent to GCC upstream: > > >> >> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598090.html > > >> > > > >> > I applied that patch on top of GCC 12.1.0 and it appears to fix the > > >> > bpftool gen object bug. > > >> > > > >> > I am however now hitting a different error during skeleton generation: > > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > > >> > gen skeleton src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > > >> > libbpf: elf: skipping unrecognized data section(9) .comment > > >> > libbpf: failed to alloc map 'restrict.bss' content buffer: -22 > > >> > Error: failed to open BPF object file: Invalid argument > > >> > > >> What is the size of the .bss section in the object file? Try with: > > >> > > >> $ size restrict-ifaces.bpf.o > > > > > > $ size output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > > > text data bss dec hex filename > > > 386 25 0 411 19b > > > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > > > > Right, so the .bss section is empty. I see a `const volatile unsigned > > char is_allow_list = 0;' in restrict-ifaces.bpf.c, but that goes to > > .data and not to .bss, as expected. > > > > If you build restrict-ifaces.bpf.o with LLVM, is the bss still empty? I > > don't think the code in libbpf.c even checks for this eventuality... > > LLVM version(which skeleton generation works with): > $ size restrict-ifaces.bpf.o > text data bss dec hex filename > 323 24 0 347 15b restrict-ifaces.bpf.o > > $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > btf dump file restrict-ifaces.bpf.o format raw > [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=34 > [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=35 > [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 'sd_restrictif_i' type_id=24 linkage=global > [27] CONST '(anon)' type_id=28 > [28] VOLATILE '(anon)' type_id=9 > [29] VAR 'is_allow_list' type_id=27, linkage=global > [30] CONST '(anon)' type_id=31 > [31] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED > [32] ARRAY '(anon)' type_id=30 index_type_id=4 nr_elems=18 > [33] VAR '_license' type_id=32, linkage=static > [34] FWD 'bpf_flow_keys' fwd_kind=struct > [35] FWD 'bpf_sock' fwd_kind=struct > [36] DATASEC '.rodata' size=1 vlen=1 > type_id=29 offset=0 size=1 (VAR 'is_allow_list') > [37] DATASEC 'license' size=18 vlen=1 > type_id=33 offset=0 size=18 (VAR '_license') > [38] DATASEC '.maps' size=24 vlen=1 > type_id=12 offset=0 size=24 (VAR 'sd_restrictif') > Skeleton generation debug output for GCC(failing) and LLVM(working) which may be helpful: GCC: $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool --debug gen skeleton output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o libbpf: loading object 'restrict_ifaces_bpf' from buffer libbpf: elf: section(2) .symtab, size 336, link 1, flags 0, type=2 libbpf: elf: section(3) .data, size 1, link 0, flags 3, type=1 libbpf: elf: section(4) .bss, size 0, link 0, flags 3, type=8 libbpf: elf: section(5) cgroup_skb/egress, size 184, link 0, flags 6, type=1 libbpf: sec 'cgroup_skb/egress': found program 'sd_restrictif_e' at insn offset 0 (0 bytes), code size 23 insns (184 bytes) libbpf: elf: section(6) cgroup_skb/ingress, size 184, link 0, flags 6, type=1 libbpf: sec 'cgroup_skb/ingress': found program 'sd_restrictif_i' at insn offset 0 (0 bytes), code size 23 insns (184 bytes) libbpf: elf: section(7) license, size 18, link 0, flags 2, type=1 libbpf: license of restrict_ifaces_bpf is LGPL-2.1-or-later libbpf: elf: section(8) .maps, size 24, link 0, flags 3, type=1 libbpf: elf: section(9) .comment, size 49, link 0, flags 30, type=1 libbpf: elf: skipping unrecognized data section(9) .comment libbpf: elf: section(10) .relcgroup_skb/egress, size 32, link 2, flags 40, type=9 libbpf: elf: section(11) .relcgroup_skb/ingress, size 32, link 2, flags 40, type=9 libbpf: elf: section(12) .BTF, size 3606, link 0, flags 0, type=1 libbpf: looking for externs among 14 symbols... libbpf: collected 0 externs total libbpf: map 'sd_restrictif': at sec_idx 8, offset 0. libbpf: map 'sd_restrictif': found type = 1. libbpf: map 'sd_restrictif': found key [12], sz = 4. libbpf: map 'sd_restrictif': found value [3], sz = 1. libbpf: map 'restrict.data' (global data): at sec_idx 3, offset 0, flags 400. libbpf: map 1 is "restrict.data" libbpf: map 'restrict.bss' (global data): at sec_idx 4, offset 0, flags 400. libbpf: failed to alloc map 'restrict.bss' content buffer: -22 Error: failed to open BPF object file: Invalid argument LLVM: $ /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool --debug gen skeleton restrict-ifaces.bpf.o libbpf: loading object 'restrict_ifaces_bpf' from buffer libbpf: elf: section(2) .symtab, size 384, link 1, flags 0, type=2 libbpf: elf: section(3) cgroup_skb/egress, size 152, link 0, flags 6, type=1 libbpf: sec 'cgroup_skb/egress': found program 'sd_restrictif_e' at insn offset 0 (0 bytes), code size 19 insns (152 bytes) libbpf: elf: section(4) cgroup_skb/ingress, size 152, link 0, flags 6, type=1 libbpf: sec 'cgroup_skb/ingress': found program 'sd_restrictif_i' at insn offset 0 (0 bytes), code size 19 insns (152 bytes) libbpf: elf: section(5) .rodata, size 1, link 0, flags 2, type=1 libbpf: elf: section(6) license, size 18, link 0, flags 2, type=1 libbpf: license of restrict_ifaces_bpf is LGPL-2.1-or-later libbpf: elf: section(7) .maps, size 24, link 0, flags 3, type=1 libbpf: elf: section(8) .relcgroup_skb/egress, size 32, link 2, flags 40, type=9 libbpf: elf: section(9) .relcgroup_skb/ingress, size 32, link 2, flags 40, type=9 libbpf: elf: section(10) .BTF, size 1988, link 0, flags 0, type=1 libbpf: elf: section(11) .BTF.ext, size 376, link 0, flags 0, type=1 libbpf: looking for externs among 16 symbols... libbpf: collected 0 externs total libbpf: map 'sd_restrictif': at sec_idx 7, offset 0. libbpf: map 'sd_restrictif': found type = 1. libbpf: map 'sd_restrictif': found key [6], sz = 4. libbpf: map 'sd_restrictif': found value [9], sz = 1. libbpf: map 'restrict.rodata' (global data): at sec_idx 5, offset 0, flags 480. libbpf: map 1 is "restrict.rodata" libbpf: sec '.relcgroup_skb/egress': collecting relocation for section(3) 'cgroup_skb/egress' libbpf: sec '.relcgroup_skb/egress': relo #0: insn #4 against 'sd_restrictif' libbpf: prog 'sd_restrictif_e': found map 0 (sd_restrictif, sec 7, off 0) for insn #4 libbpf: sec '.relcgroup_skb/egress': relo #1: insn #7 against 'is_allow_list' libbpf: prog 'sd_restrictif_e': found data map 1 (restrict.rodata, sec 5, off 0) for insn 7 libbpf: sec '.relcgroup_skb/ingress': collecting relocation for section(4) 'cgroup_skb/ingress' libbpf: sec '.relcgroup_skb/ingress': relo #0: insn #4 against 'sd_restrictif' libbpf: prog 'sd_restrictif_i': found map 0 (sd_restrictif, sec 7, off 0) for insn #4 libbpf: sec '.relcgroup_skb/ingress': relo #1: insn #7 against 'is_allow_list' libbpf: prog 'sd_restrictif_i': found data map 1 (restrict.rodata, sec 5, off 0) for insn 7 > > > > >> > > >> Looking at libbpf.c, it seems to me that this may be due of trying to > > >> mmap 0 bytes in `bpf_object__init_internal_map': > > >> > > >> map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE, > > >> MAP_SHARED | MAP_ANONYMOUS, -1, 0); > > >> if (map->mmaped == MAP_FAILED) { > > >> err = -errno; > > >> map->mmaped = NULL; > > >> pr_warn("failed to alloc map '%s' content buffer: %d\n", > > >> map->name, err); > > >> zfree(&map->real_name); > > >> zfree(&map->name); > > >> return err; > > >> } > > >> > > >> I see no check for zero sized sections in > > >> bpf_object__init_global_data_maps. > > >> > > >> Is maybe GCC failing to allocate stuff in BSS that is supposed to be > > >> there? > > >> > > >> > Stripped file passed to gen skeleton: > > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > > >> > btf dump file > > >> > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.o > > >> > format raw > > >> > [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] VAR '_license' type_id=43, linkage=static > > >> > [50] VAR 'is_allow_list' type_id=5, linkage=global > > >> > [51] VAR 'sd_restrictif' type_id=37, linkage=global > > >> > [52] FUNC 'sd_restrictif_i' type_id=47 linkage=global > > >> > [53] FUNC 'sd_restrictif_e' type_id=47 linkage=global > > >> > [54] FUNC 'restrict_network_interfaces_impl' type_id=47 linkage=static > > >> > [55] DATASEC '.data' size=1 vlen=1 > > >> > type_id=50 offset=0 size=1 (VAR 'is_allow_list') > > >> > [56] DATASEC 'license' size=18 vlen=1 > > >> > type_id=49 offset=0 size=18 (VAR '_license') > > >> > [57] DATASEC '.maps' size=24 vlen=1 > > >> > type_id=51 offset=0 size=24 (VAR 'sd_restrictif') > > >> > > > >> > File before being stripped using bpftool gen object: > > >> > /home/buildroot/buildroot/output/per-package/systemd/host/sbin/bpftool > > >> > btf dump file > > >> > output/build/systemd-custom/build/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o > > >> > format raw > > >> > [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 'is_allow_list' type_id=5, linkage=global > > >> > [53] VAR 'sd_restrictif' type_id=37, linkage=global > > >> > [54] FUNC 'bpf_map_lookup_elem' type_id=44 linkage=global > > >> > [55] FUNC 'sd_restrictif_i' type_id=47 linkage=global > > >> > [56] FUNC 'sd_restrictif_e' type_id=49 linkage=global > > >> > [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=53 offset=0 size=24 (VAR 'sd_restrictif') > > >> > [60] DATASEC '.data' size=0 vlen=1 > > >> > type_id=52 offset=0 size=1 (VAR 'is_allow_list') > > >> > > > >> >> > > >> >> >> GCC is wrong, clearly. This function is global ([0]) and libbpf > > >> >> >> expects it to be marked as such in BTF. > > >> >> >> > > >> >> >> > > >> > https://github.com/systemd/systemd/blob/main/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c#L42-L50 > > >> >> >> > > >> >> >> > > >> >> >>> 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 > > >> >> >> > > >> >> >> [...]
