Re: [PATCH 4/5] samples/bpf: fix tracex5_user build error

From: Daniel Borkmann
Date: Tue May 21 2019 - 11:25:04 EST


On 05/18/2019 02:46 AM, Matteo Croce wrote:
> Add missing symbols to tools/include/linux/filter.h to fix a build failure:
>
> make -C samples/bpf/../../tools/lib/bpf/ RM='rm -rf' LDFLAGS= srctree=samples/bpf/../../ O=
> HOSTCC samples/bpf/tracex5_user.o
> samples/bpf/tracex5_user.c: In function âinstall_accept_all_seccompâ:
> samples/bpf/tracex5_user.c:17:21: error: array type has incomplete element type âstruct sock_filterâ
> 17 | struct sock_filter filter[] = {
> | ^~~~~~
> samples/bpf/tracex5_user.c:18:3: warning: implicit declaration of function âBPF_STMTâ; did you mean âBPF_STXâ? [-Wimplicit-function-declaration]
> 18 | BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
> | ^~~~~~~~
> | BPF_STX
> samples/bpf/tracex5_user.c:20:9: error: variable âprogâ has initializer but incomplete type
> 20 | struct sock_fprog prog = {
> | ^~~~~~~~~~
> samples/bpf/tracex5_user.c:21:4: error: âstruct sock_fprogâ has no member named âlenâ
> 21 | .len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
> | ^~~
> samples/bpf/tracex5_user.c:21:10: warning: excess elements in struct initializer
> 21 | .len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
> | ^
> samples/bpf/tracex5_user.c:21:10: note: (near initialization for âprogâ)
> samples/bpf/tracex5_user.c:22:4: error: âstruct sock_fprogâ has no member named âfilterâ
> 22 | .filter = filter,
> | ^~~~~~
> samples/bpf/tracex5_user.c:22:13: warning: excess elements in struct initializer
> 22 | .filter = filter,
> | ^~~~~~
> samples/bpf/tracex5_user.c:22:13: note: (near initialization for âprogâ)
> samples/bpf/tracex5_user.c:20:20: error: storage size of âprogâ isnât known
> 20 | struct sock_fprog prog = {
> | ^~~~
> samples/bpf/tracex5_user.c:20:20: warning: unused variable âprogâ [-Wunused-variable]
> samples/bpf/tracex5_user.c:17:21: warning: unused variable âfilterâ [-Wunused-variable]
> 17 | struct sock_filter filter[] = {
> | ^~~~~~
> make[2]: *** [scripts/Makefile.host:109: samples/bpf/tracex5_user.o] Error 1
> make[1]: *** [Makefile:1763: samples/bpf/] Error 2
>
> Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
> ---
> tools/include/linux/filter.h | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/tools/include/linux/filter.h b/tools/include/linux/filter.h
> index ca28b6ab8db7..6b2ed7eccfa5 100644
> --- a/tools/include/linux/filter.h
> +++ b/tools/include/linux/filter.h
> @@ -7,6 +7,33 @@
>
> #include <linux/bpf.h>

This here is also mixing UAPI code below into non-UAPI headers in
tooling infrastructure ..

> +/*
> + * Try and keep these values and structures similar to BSD, especially
> + * the BPF code definitions which need to match so you can share filters
> + */
> +
> +struct sock_filter { /* Filter block */
> + __u16 code; /* Actual filter code */
> + __u8 jt; /* Jump true */
> + __u8 jf; /* Jump false */
> + __u32 k; /* Generic multiuse field */
> +};
> +
> +struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
> + unsigned short len; /* Number of filter blocks */
> + struct sock_filter __user *filter;
> +};
> +
> +/*
> + * Macros for filter block array initializers.
> + */
> +#ifndef BPF_STMT
> +#define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
> +#endif
> +#ifndef BPF_JUMP
> +#define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
> +#endif
> +
> /* ArgX, context and stack frame pointer register positions. Note,
> * Arg1, Arg2, Arg3, etc are used as argument mappings of function
> * calls in BPF_CALL instruction.
>