原文
// mov rdx, <wordLen>
*cast(char*)(code + 14) = 0x48;
*cast(char*)(code + 15) = 0xC7;
*cast(char*)(code + 16) = 0xC2;
*cast(char*)(code + 17) = 12;
*cast(char*)(code + 18) = 0x00;
*cast(char*)(code + 19) = 0x00;
*cast(char*)(code + 20) = 0x00;
// mov rdx, <分配位置>
*cast(char*)(code + 21) = 0x48;
*cast(char*)(code + 22) = 0xC7;
*cast(char*)(code + 23) = 0xC1;
*cast(long*)(code + 24) = cast(long)data;
*cast(char*)(code + 32) = 0x00;
指令是错的,给RDX
写了两次,用mov sign_extend imm32, reg64
替换mov imm64, reg64 (0x48 0xBA?)
.
*cast(char*)(code + 32) = 0x00;
附加0
是什么意思.
答案:
import core.stdc.stdio;
import core.stdc.string;
import core.stdc.stdlib;
import core.sys.posix.sys.mman;
void putbytes(char **code, const char *bytes) {
uint bt;
for (int i = 0, n; sscanf(bytes + i, "%x%n", &bt, &n) == 1; i += n)
{ *(*code)++ = cast(char)bt; }
}
void putdata(char **code, char** data) {
memcpy(*code, data, (*data).sizeof);
*code += (*data).sizeof;
}
extern (C) void main() {
char *data = cast(char*)mmap(null, cast(ulong)15, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
strcpy(data, "你好,世界");
char *code = cast(char*)mmap(null, cast(ulong)500, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
char *pos = code;
// 调用写,并退出系统调用
putbytes(&pos, "48 C7 C0 1 0 0 0"); // mov rax, 0x01 (写syscall)
putbytes(&pos, "48 C7 C7 1 0 0 0"); // mov rdi, 0x01 (stdout)
putbytes(&pos, "48 C7 C2 D 0 0 0"); // mov rdx, 13 (串长)
putbytes(&pos, "48 BE"); // movabs rsi, data (串地址)
putdata(&pos, &data);
putbytes(&pos, "0F 05"); // syscall
putbytes(&pos, "48 C7 C0 3C 0 0 0"); // mov rax, 0x3C (exit syscall)
putbytes(&pos, "0F 05"); // syscall
// 执行代码.
(cast(void* function())code)();
}