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9
10#define _GNU_SOURCE
11
12#include <assert.h>
13#include <stdlib.h>
14#include <sys/syscall.h>
15#include <sys/signal.h>
16#include <sys/ucontext.h>
17#include <unistd.h>
18#include <stdio.h>
19#include <string.h>
20#include <inttypes.h>
21#include <sys/mman.h>
22#include <err.h>
23#include <stddef.h>
24#include <stdbool.h>
25#include <errno.h>
26#include <sys/vm86.h>
27
28static unsigned long load_addr = 0x10000;
29static int nerrs = 0;
30
31static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
32 int flags)
33{
34 struct sigaction sa;
35 memset(&sa, 0, sizeof(sa));
36 sa.sa_sigaction = handler;
37 sa.sa_flags = SA_SIGINFO | flags;
38 sigemptyset(&sa.sa_mask);
39 if (sigaction(sig, &sa, 0))
40 err(1, "sigaction");
41}
42
43static void clearhandler(int sig)
44{
45 struct sigaction sa;
46 memset(&sa, 0, sizeof(sa));
47 sa.sa_handler = SIG_DFL;
48 sigemptyset(&sa.sa_mask);
49 if (sigaction(sig, &sa, 0))
50 err(1, "sigaction");
51}
52
53static sig_atomic_t got_signal;
54
55static void sighandler(int sig, siginfo_t *info, void *ctx_void)
56{
57 ucontext_t *ctx = (ucontext_t*)ctx_void;
58
59 if (ctx->uc_mcontext.gregs[REG_EFL] & X86_EFLAGS_VM ||
60 (ctx->uc_mcontext.gregs[REG_CS] & 3) != 3) {
61 printf("[FAIL]\tSignal frame should not reflect vm86 mode\n");
62 nerrs++;
63 }
64
65 const char *signame;
66 if (sig == SIGSEGV)
67 signame = "SIGSEGV";
68 else if (sig == SIGILL)
69 signame = "SIGILL";
70 else
71 signame = "unexpected signal";
72
73 printf("[INFO]\t%s: FLAGS = 0x%lx, CS = 0x%hx\n", signame,
74 (unsigned long)ctx->uc_mcontext.gregs[REG_EFL],
75 (unsigned short)ctx->uc_mcontext.gregs[REG_CS]);
76
77 got_signal = 1;
78}
79
80asm (
81 ".pushsection .rodata\n\t"
82 ".type vmcode_bound, @object\n\t"
83 "vmcode:\n\t"
84 "vmcode_bound:\n\t"
85 ".code16\n\t"
86 "bound %ax, (2048)\n\t"
87 "int3\n\t"
88 "vmcode_sysenter:\n\t"
89 "sysenter\n\t"
90 "vmcode_syscall:\n\t"
91 "syscall\n\t"
92 "vmcode_sti:\n\t"
93 "sti\n\t"
94 "vmcode_int3:\n\t"
95 "int3\n\t"
96 "vmcode_int80:\n\t"
97 "int $0x80\n\t"
98 ".size vmcode, . - vmcode\n\t"
99 "end_vmcode:\n\t"
100 ".code32\n\t"
101 ".popsection"
102 );
103
104extern unsigned char vmcode[], end_vmcode[];
105extern unsigned char vmcode_bound[], vmcode_sysenter[], vmcode_syscall[],
106 vmcode_sti[], vmcode_int3[], vmcode_int80[];
107
108
109static bool do_test(struct vm86plus_struct *v86, unsigned long eip,
110 unsigned int rettype, unsigned int retarg,
111 const char *text)
112{
113 long ret;
114
115 printf("[RUN]\t%s from vm86 mode\n", text);
116 v86->regs.eip = eip;
117 ret = vm86(VM86_ENTER, v86);
118
119 if (ret == -1 && (errno == ENOSYS || errno == EPERM)) {
120 printf("[SKIP]\tvm86 %s\n",
121 errno == ENOSYS ? "not supported" : "not allowed");
122 return false;
123 }
124
125 if (VM86_TYPE(ret) == VM86_INTx) {
126 char trapname[32];
127 int trapno = VM86_ARG(ret);
128 if (trapno == 13)
129 strcpy(trapname, "GP");
130 else if (trapno == 5)
131 strcpy(trapname, "BR");
132 else if (trapno == 14)
133 strcpy(trapname, "PF");
134 else
135 sprintf(trapname, "%d", trapno);
136
137 printf("[INFO]\tExited vm86 mode due to #%s\n", trapname);
138 } else if (VM86_TYPE(ret) == VM86_UNKNOWN) {
139 printf("[INFO]\tExited vm86 mode due to unhandled GP fault\n");
140 } else if (VM86_TYPE(ret) == VM86_TRAP) {
141 printf("[INFO]\tExited vm86 mode due to a trap (arg=%ld)\n",
142 VM86_ARG(ret));
143 } else if (VM86_TYPE(ret) == VM86_SIGNAL) {
144 printf("[INFO]\tExited vm86 mode due to a signal\n");
145 } else if (VM86_TYPE(ret) == VM86_STI) {
146 printf("[INFO]\tExited vm86 mode due to STI\n");
147 } else {
148 printf("[INFO]\tExited vm86 mode due to type %ld, arg %ld\n",
149 VM86_TYPE(ret), VM86_ARG(ret));
150 }
151
152 if (rettype == -1 ||
153 (VM86_TYPE(ret) == rettype && VM86_ARG(ret) == retarg)) {
154 printf("[OK]\tReturned correctly\n");
155 } else {
156 printf("[FAIL]\tIncorrect return reason\n");
157 nerrs++;
158 }
159
160 return true;
161}
162
163int main(void)
164{
165 struct vm86plus_struct v86;
166 unsigned char *addr = mmap((void *)load_addr, 4096,
167 PROT_READ | PROT_WRITE | PROT_EXEC,
168 MAP_ANONYMOUS | MAP_PRIVATE, -1,0);
169 if (addr != (unsigned char *)load_addr)
170 err(1, "mmap");
171
172 memcpy(addr, vmcode, end_vmcode - vmcode);
173 addr[2048] = 2;
174 addr[2050] = 3;
175
176 memset(&v86, 0, sizeof(v86));
177
178 v86.regs.cs = load_addr / 16;
179 v86.regs.ss = load_addr / 16;
180 v86.regs.ds = load_addr / 16;
181 v86.regs.es = load_addr / 16;
182
183 assert((v86.regs.cs & 3) == 0);
184
185
186 do_test(&v86, vmcode_bound - vmcode, VM86_INTx, 5, "#BR");
187
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191
192
193
194 sethandler(SIGILL, sighandler, 0);
195 do_test(&v86, vmcode_sysenter - vmcode, -1, 0, "SYSENTER");
196 clearhandler(SIGILL);
197
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201
202
203
204
205 sethandler(SIGILL, sighandler, 0);
206 do_test(&v86, vmcode_syscall - vmcode, VM86_SIGNAL, 0, "SYSCALL");
207 clearhandler(SIGILL);
208
209
210 v86.regs.eflags |= X86_EFLAGS_VIP;
211 v86.regs.eflags &= ~X86_EFLAGS_IF;
212 do_test(&v86, vmcode_sti - vmcode, VM86_STI, 0, "STI with VIP set");
213
214
215 do_test(&v86, vmcode_int3 - vmcode, VM86_TRAP, 3, "INT3");
216
217
218 v86.regs.eax = (unsigned int)-1;
219 do_test(&v86, vmcode_int80 - vmcode, VM86_INTx, 0x80, "int80");
220
221
222 v86.regs.cs = 0;
223 v86.regs.ss = 0;
224 sethandler(SIGSEGV, sighandler, 0);
225 got_signal = 0;
226 if (do_test(&v86, 0, VM86_SIGNAL, 0, "Execute null pointer") &&
227 !got_signal) {
228 printf("[FAIL]\tDid not receive SIGSEGV\n");
229 nerrs++;
230 }
231 clearhandler(SIGSEGV);
232
233
234 if (fork() > 0)
235 return 0;
236
237 return (nerrs == 0 ? 0 : 1);
238}
239
