| 1 | /*
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| 2 | * Linux test app for https://www.virtualbox.org/ticket/17961
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| 3 | *
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| 4 | * gcc vmdetect.c -std=gnu11 -masm=intel -o vmdetect
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| 5 | *
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| 6 | */
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| 7 |
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| 8 | #define _POSIX_C_SOURCE 200809L
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| 9 |
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| 10 | #include <signal.h>
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| 11 | #include <stdio.h>
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| 12 |
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| 13 | #if __x86_64__
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| 14 | #define ENABLE_TF() asm( \
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| 15 | "pushf;" \
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| 16 | "or WORD ptr[rsp], 0x100;" \
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| 17 | "popf;" \
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| 18 | );
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| 19 |
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| 20 | #define DISABLE_TF() asm( \
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| 21 | "pushf;" \
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| 22 | "and WORD ptr[rsp], 0xFFEF;" \
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| 23 | "popf;" \
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| 24 | );
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| 25 | #else
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| 26 | #define ENABLE_TF() asm( \
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| 27 | "pushf;" \
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| 28 | "or WORD ptr[esp], 0x100;" \
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| 29 | "popf;" \
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| 30 | );
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| 31 |
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| 32 | #define DISABLE_TF() asm( \
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| 33 | "pushf;" \
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| 34 | "and WORD ptr[esp], 0xFFEF;" \
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| 35 | "popf;" \
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| 36 | );
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| 37 | #endif
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| 38 |
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| 39 | static int codepoint = -1;
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| 40 |
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| 41 | static void handler(int signo, siginfo_t *info, void *context) {
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| 42 | // store codepoint of first exception
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| 43 | if (codepoint < 0) {
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| 44 | codepoint = *(unsigned char*)info->si_addr;
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| 45 | }
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| 46 | }
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| 47 |
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| 48 |
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| 49 | struct sigaction handler_act = {
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| 50 | .sa_sigaction = &handler,
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| 51 | .sa_flags = SA_SIGINFO,
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| 52 | };
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| 53 |
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| 54 | void cpuid_test()
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| 55 | {
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| 56 | ENABLE_TF();
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| 57 |
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| 58 | asm(
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| 59 | "cpuid;"
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| 60 | "nop;" // normal TF
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| 61 | "int 3;" // in VM
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| 62 | : /* no output */
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| 63 | : /* no input */
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| 64 | : "eax", "ebx", "ecx", "edx" /* clobber list */
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| 65 | );
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| 66 |
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| 67 | DISABLE_TF();
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| 68 | }
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| 69 |
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| 70 | int main(int argc, char *argv[]) {
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| 71 | if (sigaction(SIGTRAP, &handler_act, NULL) < 0) {
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| 72 | printf("Error installing signal handler");
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| 73 | return 1;
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| 74 | }
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| 75 |
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| 76 | cpuid_test();
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| 77 |
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| 78 | printf("Found opcode 0x%02hhX\n", codepoint);
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| 79 | if (codepoint == 0x90) {
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| 80 | printf("Trapped on nop, we are running on a real machine\n");
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| 81 | } else if (codepoint == 0xCC) {
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| 82 | printf("Trapped on int3, we are running in a VM\n");
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| 83 | } else {
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| 84 | printf("Unexpected trap location.\n");
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| 85 | }
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| 86 |
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| 87 | return 0;
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| 88 | }
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| 89 |
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