// SPDX-License-Identifier: GPL-2.0/* * binfmt_misc_ops handler for the transparent-mode case: match a synthetic * riscv ELF header and run the asserting interpreter transparently - the * argument vector untouched, the binary in AT_EXECFD and mm->exe_file * labeled with the binary. */#include "vmlinux.h"#include <bpf/bpf_helpers.h>#include <bpf/bpf_tracing.h> char _license[] SEC("license") = "GPL"; #define EI_CLASS	4#define ELFCLASS64	2#define EM_RISCV	243 extern int bpf_binprm_set_interp(struct linux_binprm *bprm, const char *path,				 size_t path__sz) __ksym;extern int bpf_binprm_set_flags(struct linux_binprm *bprm,				enum bpf_binprm_flags flags) __ksym; SEC("struct_ops.s/match")bool BPF_PROG(transparent_match, struct linux_binprm *bprm){	__u16 machine; 	if (bprm->buf[0] != 0x7f || bprm->buf[1] != 'E' ||	    bprm->buf[2] != 'L' || bprm->buf[3] != 'F' ||	    bprm->buf[EI_CLASS] != ELFCLASS64)		return false; 	/* e_machine is a 16-bit little-endian field at offset 18. */	machine = (__u8)bprm->buf[18] | ((__u16)(__u8)bprm->buf[19] << 8);	return machine == EM_RISCV;} SEC("struct_ops.s/load")int BPF_PROG(transparent_load, struct linux_binprm *bprm){	char interp[] = "/tmp/binfmt_transparent_interp";	int err; 	err = bpf_binprm_set_flags(bprm, BPF_BINPRM_TRANSPARENT);	if (err)		return err; 	/* @path__sz includes the terminating NUL; 0 commits the selection. */	return bpf_binprm_set_interp(bprm, interp, sizeof(interp));} SEC(".struct_ops.link")struct binfmt_misc_ops transparent = {	.match = (void *)transparent_match,	.load = (void *)transparent_load,	.name = "transparent",};