On Sat, Jul 9, 2022 at 4:41 PM Jose E. Marchesi <jose.marchesi@xxxxxxxxxx> wrote: > > > > 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: > > Indeed it was helpful :) > > The GNU assembler generates an empty .bss section. This is a well > established behavior in GAS that happens in all supported targets. > > The LLVM assembler doesn't generate an empty .bss section. > > bpftool chokes on the empty .bss section. > > In this case I would suggest to fix bpf_object__init_global_data_maps in > order to skip empty sections. > > Something like this: Hmm, that seems to segfault: Starting program: /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 [Thread debugging using libthread_db enabled] Using host libthread_db library "/usr/lib/libthread_db.so.1". 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. Program received signal SIGSEGV, Segmentation fault. 0x0000aaaaaab4fd2c in bpf_object.init_maps () (gdb) bt #0 0x0000aaaaaab4fd2c in bpf_object.init_maps () #1 0x0000aaaaaab52178 in bpf_object_open.part () #2 0x0000aaaaaab544e8 in bpf_object.open_mem () #3 0x0000aaaaaab2a58c in do_skeleton () #4 0x0000aaaaaab1e204 in main () > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index e89cc9c885b3..e3a6808f0bb6 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -1591,6 +1591,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) > for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { > sec_desc = &obj->efile.secs[sec_idx]; > > + /* Skip empty sections. */ > + if (sec_desc->data->d_size == 0) > + continue; > + > switch (sec_desc->sec_type) { > case SEC_DATA: > sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx)); > > > 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 > >> > >> >> >> > >> > >> >> >> [...]
