libbpf: prog 'lsm_bpf': failed to attach: Device or resource busy

[chunbuwan]

I have compiled android 15 aosp, car sdk x86 64 userdebug, and I want bpf lsm to take effect on it.
I used the lsm in the libbpf-bootstrap example and compiled lsm.bpf.c into lsm.bpf.o using android.bp:

bpf {
    name: "lsm.bpf.o",
    srcs: ["lsm.bpf.c"],
    include_dirs: ["external/libbpf/src",
    "system/bpf/include/vmlinux/android15_6.6/x86_64",],
    cflags: [
        "-Wno-all",
        "-Wno-error",
	"-Wno-unused-parameter",
    ],
}

Then, use bpftool and lsm.bpf.o to generate lsm.skel.h, and then compile Lsm.c into the executable file lsm using Android.bp and lsm.skel.h:

cc_binary {
    name: "lsm",

    cflags: [
        "-Wno-all",
        "-Wno-error",
	"-Wno-unused-parameter",
    ],
    include_dirs: ["external/libbpf/src",],
     shared_libs: [
        "liblog",
        "libcutils",
        "libbpf_android",
        "libbase",
        "libnetdutils",
        "libbpf_bcc",
        "libbpf"
    ],
    srcs: [
        "lsm.c",
    ],
}

Finally, the executable file lsm was pushed into the emulator and run./lsm, but an error was reported:

emulator_car64_x86_64:/data/local/tmp # ./lsm
libbpf: loading object 'lsm_bpf' from buffer
libbpf: elf: section(3) lsm/bpf, size 96, link 0, flags 6, type=1
libbpf: sec 'lsm/bpf': found program 'lsm_bpf' at insn offset 0 (0 bytes), code size 12 insns (96 bytes)
libbpf: elf: section(4) .rellsm/bpf, size 16, link 9, flags 40, type=9
libbpf: elf: section(5) license, size 4, link 0, flags 3, type=1
libbpf: license of lsm_bpf is GPL
libbpf: elf: section(6) .rodata, size 24, link 0, flags 2, type=1
libbpf: elf: section(7) .BTF, size 553, link 0, flags 0, type=1
libbpf: elf: section(9) .symtab, size 120, link 1, flags 0, type=2
libbpf: looking for externs among 5 symbols...
libbpf: collected 0 externs total
libbpf: map 'lsm_bpf.rodata' (global data): at sec_idx 6, offset 0, flags 80.
libbpf: map 0 is "lsm_bpf.rodata"
libbpf: sec '.rellsm/bpf': collecting relocation for section(3) 'lsm/bpf'
libbpf: sec '.rellsm/bpf': relo #0: insn #5 against '.rodata'
libbpf: prog 'lsm_bpf': found data map 0 (lsm_bpf.rodata, sec 6, off 0) for insn 5
libbpf: object 'lsm_bpf': failed (-22) to create BPF token from '/sys/fs/bpf', skipping optional step...
libbpf: loaded kernel BTF from '/sys/kernel/btf/vmlinux'
libbpf: map 'lsm_bpf.rodata': created successfully, fd=3
libbpf: prog 'lsm_bpf': failed to attach: Device or resource busy
libbpf: prog 'lsm_bpf': failed to auto-attach: -16
Failed to attach BPF skeleton

strace ./lsm, part of the content:

bpf(BPF_BTF_LOAD, 0x7ffed3783cf0, 40)   = 4
close(4)                                = 0
bpf(BPF_BTF_LOAD, 0x7ffed3783cc0, 40)   = -1 EINVAL (Invalid argument)
bpf(BPF_BTF_LOAD, 0x7ffed3783d20, 40)   = 4
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=32, max_entries=1, map_flags=0, inner_map_fd=0, map_name="libbpf_global", map_ifindex=0}, 80) = 5
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=5, insns=0x7ffed3783d90, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 148) = 6
close(5)                                = 0
close(6)                                = 0
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=24, max_entries=1, map_flags=0x80 /* BPF_F_??? */, inner_map_fd=0, map_name="lsm_bpf.rodata", map_ifindex=0, ...}, 80) = 5
dup3(5, 3, O_CLOEXEC)                   = 3
close(5)                                = 0
write(2, "libbpf: map 'lsm_bpf.rodata': cr"..., 57libbpf: map 'lsm_bpf.rodata': created successfully, fd=3
) = 57
bpf(BPF_MAP_UPDATE_ELEM, {map_fd=3, key=0x7ffed3785160, value=0x73a7ad70e000, flags=BPF_ANY}, 32) = 0
bpf(0x16 /* BPF_??? */, 0x7ffed3783de0, 4) = 0
bpf(BPF_PROG_LOAD, {prog_type=0x1d /* BPF_PROG_TYPE_??? */, insn_cnt=12, insns=0x73a5ec6d2a20, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(6, 6, 57), prog_flags=0, prog_name="lsm_bpf", prog_ifindex=0, expected_attach_type=0x1b /* BPF_??? */, ...}, 148) = 5
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=32, max_entries=1, map_flags=0, inner_map_fd=0, map_name="libbpf_det_bind", map_ifindex=0}, 80) = 6
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2, insns=0x7ffed3783db0, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 148) = 8
bpf(0x23 /* BPF_??? */, 0x7ffed3783c40, 12) = 0
close(6)                                = 0
close(8)                                = 0
bpf(0x23 /* BPF_??? */, 0x7ffed3783de0, 12) = 0
munmap(0x73a51b6d6000, 6217728)         = 0
madvise(0x73a51b4d4000, 704512, MADV_DONTNEED) = 0
bpf(0x1c /* BPF_??? */, 0x7ffed37851b0, 64) = -1 EBUSY (Device or resource busy)
write(2, "libbpf: prog 'lsm_bpf': failed t"..., 66libbpf: prog 'lsm_bpf': failed to attach: Device or resource busy
) = 66
write(2, "libbpf: prog 'lsm_bpf': failed t"..., 51libbpf: prog 'lsm_bpf': failed to auto-attach: -16
) = 51
write(2, "Failed to attach BPF skeleton\n", 30Failed to attach BPF skeleton
) = 30

Configuration as follows:

emulator_car64_x86_64:/data/local/tmp # zcat /proc/config.gz | grep "BPF"
CONFIG_BPF=y
CONFIG_HAVE_EBPF_JIT=y
CONFIG_ARCH_WANT_DEFAULT_BPF_JIT=y
# BPF subsystem
CONFIG_BPF_SYSCALL=y
CONFIG_BPF_JIT=y
CONFIG_BPF_JIT_ALWAYS_ON=y
CONFIG_BPF_JIT_DEFAULT_ON=y
# CONFIG_BPF_UNPRIV_DEFAULT_OFF is not set
# CONFIG_BPF_PRELOAD is not set
CONFIG_BPF_LSM=y
# end of BPF subsystem
CONFIG_CGROUP_BPF=y
CONFIG_NETFILTER_BPF_LINK=y
CONFIG_NETFILTER_XT_MATCH_BPF=y
# CONFIG_BPFILTER is not set
CONFIG_NET_CLS_BPF=y
CONFIG_NET_ACT_BPF=y
# CONFIG_BPF_STREAM_PARSER is not set
CONFIG_BPF_LIRC_MODE2=y
# HID-BPF support
# end of HID-BPF support
CONFIG_FUSE_BPF=y
CONFIG_BPF_EVENTS=y
# CONFIG_TEST_BPF is not set