// SPDX-License-Identifier: GPL-2.0/* * binfmt_misc_ops handler for the selftest's bound-interpreter case: one * handler, one entry, an interpreter per guest architecture - each bound to * a file when the entry was registered rather than to a path resolved at * exec time. The load program names the one it wants; a name the entry did * not bind fails the exec, which the harness checks too. */#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 E_MACHINE_OFF	18#define EM_ARM		40#define EM_AARCH64	183#define EM_RISCV	243 extern int bpf_binprm_select_interp(struct linux_binprm *bprm,				    const char *name, size_t name__sz) __ksym; /* The guest architecture of a 64-bit ELF, or zero if it is not one. */static __u16 elf_machine(struct linux_binprm *bprm){	if (bprm->buf[0] != 0x7f || bprm->buf[1] != 'E' ||	    bprm->buf[2] != 'L' || bprm->buf[3] != 'F' ||	    bprm->buf[EI_CLASS] != ELFCLASS64)		return 0; 	/* Little-endian 16-bit field, read byte-wise for the verifier. */	return (__u8)bprm->buf[E_MACHINE_OFF] |	       ((__u16)(__u8)bprm->buf[E_MACHINE_OFF + 1] << 8);} SEC("struct_ops.s/match")bool BPF_PROG(interp_bind_match, struct linux_binprm *bprm){	__u16 machine = elf_machine(bprm); 	return machine == EM_AARCH64 || machine == EM_RISCV ||	       machine == EM_ARM;} SEC("struct_ops.s/load")int BPF_PROG(interp_bind_load, struct linux_binprm *bprm){	/*	 * Names, not paths: each one selects a file the entry pre-opened, so	 * nothing is resolved here or later, in any namespace. The buffers	 * are on the stack because the verifier rejects .rodata for a sized	 * memory argument.	 */	char first[] = "first";	char second[] = "second";	char unbound[] = "unbound"; 	switch (elf_machine(bprm)) {	case EM_AARCH64:		return bpf_binprm_select_interp(bprm, first, sizeof(first));	case EM_RISCV:		return bpf_binprm_select_interp(bprm, second, sizeof(second));	} 	/* The entry bound nothing under this name: -ENOENT fails the exec. */	return bpf_binprm_select_interp(bprm, unbound, sizeof(unbound));} SEC(".struct_ops.link")struct binfmt_misc_ops interp_bind = {	.match	= (void *)interp_bind_match,	.load	= (void *)interp_bind_load,	.name	= "interp_bind",};