> On Fri, Jul 8, 2022 at 7:46 AM Jose E. Marchesi > <jose.marchesi@xxxxxxxxxx> wrote: >> >> >> > On Fri, Jul 8, 2022 at 5:56 AM Jose E. Marchesi >> > <jose.marchesi@xxxxxxxxxx> wrote: >> >> >> >> >> >> > On Wed, Jul 6, 2022 at 11:20 AM Andrii Nakryiko >> >> > <andrii.nakryiko@xxxxxxxxx> 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 >> >> >> > >> >> >> >> >> >> GCC is wrong, clearly. This function is global ([0]) and libbpf >> >> >> expects it to be marked as such in BTF. >> >> > >> >> > Does this invocation look correct? >> >> > /home/buildroot/buildroot/output/per-package/systemd/host/bin/bpf-gcc >> >> > -O2 -mkernel=5.2 -mcpu=v3 -mco-re -gbtf -r -std=gnu11 -D__x86_64__ >> >> > -mlittle-endian -I. -idirafter >> >> > /home/buildroot/buildroot/output/per-package/systemd/host/x86_64-buildroot-linux-gnu/sysroot/usr/include >> >> > ../src/core/bpf/restrict_fs/restrict-fs.bpf.c -o >> >> > src/core/bpf/restrict_fs/restrict-fs.bpf.unstripped.o >> >> >> >> Hmm, why linking a relocatable ELF instead of just using a compiled >> >> object (with -c)? >> > >> > This bpftool gen object build stage AFAIU is needed to strip the object before >> > using it for skeleton generation, does that sound right? >> >> Thing is, `gcc -r' involves the linker. The GNU linker (ld) supports >> linking BPF objects, but AFAIK the kernel BPF objects are all supposed >> to be compiled objects, not linked as relocatable objects. (The LLVM >> BPF toolchain doesn't support linking BPF objects as far as I know.) > > Maybe bpftool needs support for a different ELF file kind? > > When I omit the '-r' flag I get this error from bpftool: > libbpf: unsupported kind of ELF file Yes, because if you omit -r you are basically linking an ELF executable, which libbpf doesn't support. If you instead replace -r with -c, you will get a plain object file. >> >> That's my understanding, but note I'm not very familiar with bpftool >> (I'm trying to find time now to fix that.) >> >> >> >> >> > I've also tried without the -r(relocatable object) flag but that gives >> >> > a different error: >> >> > /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: unsupported kind of ELF file >> >> > src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o: no >> >> > error >> >> > Error: failed to link >> >> > 'src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.unstripped.o': >> >> > Unknown error -95 (-95) >> >> > >> >> > GCC without relocatable flag: >> >> > [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 'is_allow_list' type_id=5, linkage=global >> >> > [52] VAR '_license' type_id=43, linkage=static >> >> > [53] VAR 'sd_restrictif' type_id=37, 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=52 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=51 offset=0 size=1 (VAR 'is_allow_list') >> >> > >> >> >> >> >> >> 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 >> >> >> >> >> >> [...]
