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Date: Tue, 24 Apr 2018 14:42:51 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: shhuiw <shhuiw@...mail.com>
Cc: ast <ast@...nel.org>, netdev <netdev@...r.kernel.org>, yhs@...com,
peterz@...radead.org
Subject: Re: bpf: samples/bpf/sockex2: Assertion `setsockopt(sock, SOL_SOCKET,
SO_ATTACH_BPF, prog_fd, sizeof(prog_fd[0])) == 0' failed.
On 04/24/2018 09:29 AM, shhuiw wrote:
> On 04/23/18 17:53, Daniel Borkmann wrote:
>> On 04/23/2018 04:56 AM, Wang Sheng-Hui wrote:
>>> Sorry to trouble you!
>>>
>>> I run samples/bpf/sockex2 failed with
>>> "Assertion `setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, prog_fd, sizeof(prog_fd[0])) == 0' failed."
>>>
>>> Then I run " strace ./sockex2" and got:
>>> ...
>>> bind(3, {sa_family=AF_PACKET, sll_protocol=htons(ETH_P_ALL), sll_ifindex=if_nametoindex("lo"), sll_hatype=ARPHRD_NETROM, sll_pkttype=PACKET_HOST, sll_halen=0}, 20) = 0
>>> setsockopt(3, SOL_SOCKET, SO_ATTACH_BPF, [0], 4) = -1 EINVAL (Invalid argument)
>>> write(2, "sockex2: /root/linux/samples/bpf"..., 156sockex2: /root/linux/samples/bpf/sockex2_user.c:35: main: Assertion `setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, prog_fd, sizeof(prog_fd[0])) == 0' failed.
>>> ) = 156
>>> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb8ec4bf000
>>> rt_sigprocmask(SIG_UNBLOCK, [ABRT], NULL, 8) = 0
>>> rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [], 8) = 0
>>> getpid() = 3513
>>> gettid() = 3513
>>> tgkill(3513, 3513, SIGABRT) = 0
>>> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
>>> --- SIGABRT {si_signo=SIGABRT, si_code=SI_TKILL, si_pid=3513, si_uid=0} ---
>>> +++ killed by SIGABRT +++
>>> Aborted
>> [...]
>> bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_HASH, key_size=4, value_size=16, max_entries=1024}, 72) = 4
>> bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=201, insns=0x2676cd0, license="GPL", log_level=0, log_size=0, log_buf=0, kern_version=0}, 72) = 5
>> close(3) = 0
>> socket(AF_PACKET, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, 768) = 3
>> access("/proc/net", R_OK) = 0
>> access("/proc/net/unix", R_OK) = 0
>> socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 6
>> ioctl(6, SIOCGIFINDEX, {ifr_name="lo", }) = 0
>> close(6) = 0
>> bind(3, {sa_family=AF_PACKET, sll_protocol=htons(ETH_P_ALL), sll_ifindex=if_nametoindex("lo"), sll_hatype=ARPHRD_NETROM, sll_pkttype=PACKET_HOST, sll_halen=0}, 20) = 0
>> setsockopt(3, SOL_SOCKET, SO_ATTACH_BPF, [5], 4) = 0
>> pipe2([6, 7], O_CLOEXEC) = 0
>> [...]
>>
>> Works fine for me. The EINVAL in your case comes from the 'setsockopt(3, SOL_SOCKET,
>> SO_ATTACH_BPF, [0], 4)'. So you send fd 0 to SO_ATTACH_BPF, which is not a valid BPF
>> fd and therefore bails out here. You might want to debug bpf_load.c why it's failing
>> to load the program in your case, or check strace a bit further above where you do
>> the map and prog creation (as I copied in my case).
>>
>> Cheers,
>> Daniel
>>
> Daniel,
>
> I built the sample code by run
> "make O=../buildkernel samples/bpf/ LLC=/usr/bin/llc clang=/usr/bin/clang"
> while llc & clang are provided by debian:
> ~/buildkernel/samples/bpf# ls -l /usr/bin/llc
> lrwxrwxrwx 1 root root 23 Dec 4 21:34 /usr/bin/llc -> ../lib/llvm-4.0/bin/llc
> ~/buildkernel/samples/bpf# ls -l /usr/bin/clang
> lrwxrwxrwx 1 root root 25 Dec 4 21:34 /usr/bin/clang -> ../lib/llvm-4.0/bin/clang
> ~/buildkernel/samples/bpf# llc --version
> LLVM (http://llvm.org/):
> LLVM version 4.0.1
> ...
> Registered Targets:
> ...
> bpf - BPF (host endian)
> bpfeb - BPF (big endian)
> bpfel - BPF (little endian)
> ...
>
> There are 3 sockex BPF programs under samples/bpf, but only 'socket' section in sockex1_kern.o can be
> detected, sockex[23]_kern.o failed.
> ------------------------------------------------------------------------
> ~/buildkernel/samples/bpf# llvm-objdump -h ./sockex1_kern.o
> ./sockex1_kern.o: file format ELF64-BPF
> Sections:
> Idx Name Size Address Type
> 0 00000000 0000000000000000
> 1 .strtab 00000057 0000000000000000
> 2 .text 00000000 0000000000000000 TEXT DATA
> 3 socket1 00000078 0000000000000000 TEXT DATA
> 4 .relsocket1 00000010 0000000000000000
> 5 maps 0000001c 0000000000000000 DATA
> 6 license 00000004 0000000000000000 DATA
> 7 .eh_frame 00000028 0000000000000000 DATA
> 8 .rel.eh_frame 00000010 0000000000000000
> 9 .symtab 00000090 0000000000000000
>
> ~/buildkernel/samples/bpf# llvm-objdump -h ./sockex2_kern.o
> ./sockex2_kern.o: file format ELF64-BPF
> Sections:
> Idx Name Size Address Type
> 0 00000000 0000000000000000
> 1 .strtab 00000017 0000000000000000
> 2 .text 00000000 0000000000000000 TEXT DATA
> 3 .symtab 00000018 0000000000000000
>
> ~/buildkernel/samples/bpf# llvm-objdump -h ./sockex3_kern.o
> ./sockex3_kern.o: file format ELF64-BPF
> Sections:
> Idx Name Size Address Type
> 0 00000000 0000000000000000
> 1 .strtab 00000017 0000000000000000
> 2 .text 00000000 0000000000000000 TEXT DATA
> 3 .symtab 00000018 0000000000000000
>
>
> Do you know how to fix it, please?
Did you by any chance hit an error like the below during compilation? The first
sockex1_kern.o compiled fine for me from the kernel samples dir, but the second
sockex2_kern.o and subsequent bail out with "error: 'asm goto' constructs are not
supported yet":
# make
[...]
clang -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/6.4.1/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -I/home/foo/trees/bpf-next/samples/bpf \
-I./tools/testing/selftests/bpf/ \
-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
-D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types \
-Wno-gnu-variable-sized-type-not-at-end \
-Wno-address-of-packed-member -Wno-tautological-compare \
-Wno-unknown-warning-option \
-O2 -emit-llvm -c /home/foo/trees/bpf-next/samples/bpf/sockex1_kern.c -o -| llc -march=bpf -filetype=obj -o /home/foo/trees/bpf-next/samples/bpf/sockex1_kern.o
clang -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/6.4.1/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -I/home/foo/trees/bpf-next/samples/bpf \
-I./tools/testing/selftests/bpf/ \
-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
-D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types \
-Wno-gnu-variable-sized-type-not-at-end \
-Wno-address-of-packed-member -Wno-tautological-compare \
-Wno-unknown-warning-option \
-O2 -emit-llvm -c /home/foo/trees/bpf-next/samples/bpf/sockex2_kern.c -o -| llc -march=bpf -filetype=obj -o /home/foo/trees/bpf-next/samples/bpf/sockex2_kern.o
In file included from /home/foo/trees/bpf-next/samples/bpf/sockex2_kern.c:3:
In file included from ./include/uapi/linux/in.h:24:
In file included from ./include/linux/socket.h:8:
In file included from ./include/linux/uio.h:13:
In file included from ./include/linux/thread_info.h:38:
In file included from ./arch/x86/include/asm/thread_info.h:53:
./arch/x86/include/asm/cpufeature.h:150:2: error: 'asm goto' constructs are not supported yet
asm_volatile_goto("1: jmp 6f\n"
^
./include/linux/compiler-gcc.h:290:42: note: expanded from macro 'asm_volatile_goto'
#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
^
1 error generated.
[...]
Which leads to:
# llvm-objdump -h ./sockex1_kern.o
./sockex1_kern.o: file format ELF64-BPF
Sections:
Idx Name Size Address Type
0 00000000 0000000000000000
1 .strtab 00000057 0000000000000000
2 .text 00000000 0000000000000000 TEXT DATA
3 socket1 00000078 0000000000000000 TEXT DATA
4 .relsocket1 00000010 0000000000000000
5 maps 0000001c 0000000000000000 DATA
6 license 00000004 0000000000000000 DATA
7 .eh_frame 00000028 0000000000000000 DATA
8 .rel.eh_frame 00000010 0000000000000000
9 .symtab 00000090 0000000000000000
But ...
# llvm-objdump -h ./sockex2_kern.o
./sockex2_kern.o: file format ELF64-BPF
Sections:
Idx Name Size Address Type
0 00000000 0000000000000000
1 .strtab 00000017 0000000000000000
2 .text 00000000 0000000000000000 TEXT DATA
3 .symtab 00000018 0000000000000000
#
There's a fix from Yonghong here:
https://patchwork.kernel.org/patch/10341471/
Could you try with that patch?
Thanks,
Daniel
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