linux/net/bpfilter/msgfmt.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NET_BPFILTER_MSGFMT_H
#define _NET_BPFILTER_MSGFMT_H

struct mbox_request {
	__u64 addr;
	__u32 len;
	__u32 is_set;
	__u32 cmd;
	__u32 pid;
};

struct mbox_reply {
	__u32 status;
};

#endif
net: add skeleton of bpfilter kernel module bpfilter.ko consists of bpfilter_kern.c (normal kernel module code) and user mode helper code that is embedded into bpfilter.ko The steps to build bpfilter.ko are the following: - main.c is compiled by HOSTCC into the bpfilter_umh elf executable file - with quite a bit of objcopy and Makefile magic the bpfilter_umh elf file is converted into bpfilter_umh.o object file with _binary_net_bpfilter_bpfilter_umh_start and _end symbols Example: $ nm ./bld_x64/net/bpfilter/bpfilter_umh.o 0000000000004cf8 T _binary_net_bpfilter_bpfilter_umh_end 0000000000004cf8 A _binary_net_bpfilter_bpfilter_umh_size 0000000000000000 T _binary_net_bpfilter_bpfilter_umh_start - bpfilter_umh.o and bpfilter_kern.o are linked together into bpfilter.ko bpfilter_kern.c is a normal kernel module code that calls the fork_usermode_blob() helper to execute part of its own data as a user mode process. Notice that _binary_net_bpfilter_bpfilter_umh_start - end is placed into .init.rodata section, so it's freed as soon as __init function of bpfilter.ko is finished. As part of __init the bpfilter.ko does first request/reply action via two unix pipe provided by fork_usermode_blob() helper to make sure that umh is healthy. If not it will kill it via pid. Later bpfilter_process_sockopt() will be called from bpfilter hooks in get/setsockopt() to pass iptable commands into umh via bpfilter.ko If admin does 'rmmod bpfilter' the __exit code bpfilter.ko will kill umh as well. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> 2018-05-21 19:22:30 -07:00			`/* SPDX-License-Identifier: GPL-2.0 */`
			`#ifndef _NET_BPFILTER_MSGFMT_H`
			`#define _NET_BPFILTER_MSGFMT_H`

			`struct mbox_request {`
			`__u64 addr;`
			`__u32 len;`
			`__u32 is_set;`
			`__u32 cmd;`
			`__u32 pid;`
			`};`

			`struct mbox_reply {`
			`__u32 status;`
			`};`

			`#endif`