Makefile

memfd: memfd.o binary.o

binary.o: sc
	$(LD) -r -b binary -o $@ $^

sc: sc.S
	$(CC) -no-pie -nostdlib -s $< -o $@

.PHONY: clean
clean:
	rm -f sc memfd memfd.o binary.o

memfd.c

#define _GNU_SOURCE
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <stdio.h>

extern char _binary_sc_start[];
extern char _binary_sc_end[];

int main() {
  pid_t pid = getpid();
  printf("[+] pid: %d\n", pid);

  int memfd = memfd_create("hoge", MFD_CLOEXEC);
  printf("[+] memfd: %d\n", memfd);

  printf("[+] writing binary to memfd\n");
  write(memfd, _binary_sc_start, _binary_sc_end - _binary_sc_start);

  char* path = NULL;
  asprintf(&path, "/proc/%d/fd/%d", pid, memfd);
  printf("[+] executing %s\n", path);
  execl(path, "hoge", NULL);
}

sc.S

.intel_syntax noprefix
.global _start

_start:
mov rsi, offset msg
mov rdi, 1
mov rdx, 14
mov rax, rdi
syscall

xor rdi, rdi
mov rax, 60
syscall

msg:
.ascii "Hello, World!\n"