summaryrefslogtreecommitdiff
path: root/util/statetrace/arch/tracechild_amd64.cc
blob: 088e547e42db6a58f73d3f7c93b1920576971c3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
/*
 * Copyright (c) 2007 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gabe Black
 */

#include <iostream>
#include <iomanip>
#include <errno.h>
#include <sys/ptrace.h>
#include <stdint.h>

#include "tracechild_amd64.hh"

using namespace std;

char * AMD64TraceChild::regNames[numregs] = {
                //GPRs
                "rax", "rbx", "rcx", "rdx",
                //Index registers
                "rsi", "rdi",
                //Base pointer and stack pointer
                "rbp", "rsp",
                //New 64 bit mode registers
                "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
                //Segmentation registers
                "cs", "ds", "es", "fs", "gs", "ss", "fs_base", "gs_base",
                //PC
                "rip",
                //Flags
                "eflags"};

bool AMD64TraceChild::sendState(int socket)
{
    uint64_t regVal = 0;
    for(int x = 0; x <= R15; x++)
    {
        regVal = getRegVal(x);
        if(write(socket, &regVal, sizeof(regVal)) == -1)
        {
            cerr << "Write failed! " << strerror(errno) << endl;
            tracing = false;
            return false;
        }
    }
    regVal = getRegVal(RIP);
    if(write(socket, &regVal, sizeof(regVal)) == -1)
    {
        cerr << "Write failed! " << strerror(errno) << endl;
        tracing = false;
        return false;
    }
    return true;
}

int64_t AMD64TraceChild::getRegs(user_regs_struct & myregs, int num)
{
        assert(num < numregs && num >= 0);
        switch(num)
        {
                //GPRs
                case RAX: return myregs.rax;
                case RBX: return myregs.rbx;
                case RCX: return myregs.rcx;
                case RDX: return myregs.rdx;
                //Index registers
                case RSI: return myregs.rsi;
                case RDI: return myregs.rdi;
                //Base pointer and stack pointer
                case RBP: return myregs.rbp;
                case RSP: return myregs.rsp;
                //New 64 bit mode registers
                case R8: return myregs.r8;
                case R9: return myregs.r9;
                case R10: return myregs.r10;
                case R11: return myregs.r11;
                case R12: return myregs.r12;
                case R13: return myregs.r13;
                case R14: return myregs.r14;
                case R15: return myregs.r15;
                //Segmentation registers
                case CS: return myregs.cs;
                case DS: return myregs.ds;
                case ES: return myregs.es;
                case FS: return myregs.fs;
                case GS: return myregs.gs;
                case SS: return myregs.ss;
                case FS_BASE: return myregs.fs_base;
                case GS_BASE: return myregs.gs_base;
                //PC
                case RIP: return myregs.rip;
                //Flags
                case EFLAGS: return myregs.eflags;
                default:
                        assert(0);
                        return 0;
        }
}

bool AMD64TraceChild::update(int pid)
{
    oldregs = regs;
    if(ptrace(PTRACE_GETREGS, pid, 0, &regs) != 0)
    {
        cerr << "update: " << strerror(errno) << endl;
        return false;
    }
    for(unsigned int x = 0; x < numregs; x++)
        regDiffSinceUpdate[x] = (getRegVal(x) != getOldRegVal(x));
    return true;
}

AMD64TraceChild::AMD64TraceChild()
{
    for(unsigned int x = 0; x < numregs; x++)
        regDiffSinceUpdate[x] = false;
}

int64_t AMD64TraceChild::getRegVal(int num)
{
        return getRegs(regs, num);
}

int64_t AMD64TraceChild::getOldRegVal(int num)
{
        return getRegs(oldregs, num);
}

char * AMD64TraceChild::printReg(int num)
{
        sprintf(printBuffer, "0x%08X", getRegVal(num));
        return printBuffer;
}

ostream & AMD64TraceChild::outputStartState(ostream & os)
{
    uint64_t sp = getSP();
    uint64_t pc = getPC();
    char obuf[1024];
    sprintf(obuf, "Initial stack pointer = 0x%016llx\n", sp);
    os << obuf;
    sprintf(obuf, "Initial program counter = 0x%016llx\n", pc);
    os << obuf;

    //Output the argument count
    uint64_t cargc = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
    sprintf(obuf, "0x%016llx: Argc = 0x%016llx\n", sp, cargc);
    os << obuf;
    sp += 8;

    //Output argv pointers
    int argCount = 0;
    uint64_t cargv;
    do
    {
        cargv = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sprintf(obuf, "0x%016llx: argv[%d] = 0x%016llx\n",
                sp, argCount++, cargv);
        os << obuf;
        sp += 8;
    } while(cargv);

    //Output the envp pointers
    int envCount = 0;
    uint64_t cenvp;
    do
    {
        cenvp = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sprintf(obuf, "0x%016llx: envp[%d] = 0x%016llx\n",
                sp, envCount++, cenvp);
        os << obuf;
        sp += 8;
    } while(cenvp);
    uint64_t auxType, auxVal;
    do
    {
        auxType = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sp += 8;
        auxVal = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        sp += 8;
        sprintf(obuf, "0x%016llx: Auxiliary vector = {0x%016llx, 0x%016llx}\n",
                sp - 16, auxType, auxVal);
        os << obuf;
    } while(auxType != 0 || auxVal != 0);
    //Print out the argument strings, environment strings, and file name.
    string current;
    uint64_t buf;
    uint64_t currentStart = sp;
    bool clearedInitialPadding = false;
    do
    {
        buf = ptrace(PTRACE_PEEKDATA, pid, sp, 0);
        char * cbuf = (char *)&buf;
        for(int x = 0; x < sizeof(uint64_t); x++)
        {
            if(cbuf[x])
                current += cbuf[x];
            else
            {
                sprintf(obuf, "0x%016llx: \"%s\"\n",
                        currentStart, current.c_str());
                os << obuf;
                current = "";
                currentStart = sp + x + 1;
            }
        }
        sp += 8;
        clearedInitialPadding = clearedInitialPadding || buf != 0;
    } while(!clearedInitialPadding || buf != 0);
    return os;
}

uint64_t AMD64TraceChild::findSyscall()
{
    uint64_t rip = getPC();
    bool foundOpcode = false;
    bool twoByteOpcode = false;
    for(;;)
    {
        uint64_t buf = ptrace(PTRACE_PEEKDATA, pid, rip, 0);
        for(int i = 0; i < sizeof(uint64_t); i++)
        {
            unsigned char byte = buf & 0xFF;
            if(!foundOpcode)
            {
                if(!(byte == 0x66 || //operand override
                     byte == 0x67 || //address override
                     byte == 0x2E || //cs
                     byte == 0x3E || //ds
                     byte == 0x26 || //es
                     byte == 0x64 || //fs
                     byte == 0x65 || //gs
                     byte == 0x36 || //ss
                     byte == 0xF0 || //lock
                     byte == 0xF2 || //repe
                     byte == 0xF3 || //repne
                     (byte >= 0x40 && byte <= 0x4F) // REX
                    ))
                {
                    foundOpcode = true;
                }
            }
            if(foundOpcode)
            {
                if(twoByteOpcode)
                {
                    //SYSCALL or SYSENTER
                    if(byte == 0x05 || byte == 0x34)
                        return rip + 1;
                    else
                        return 0;
                }
                if(!twoByteOpcode)
                {
                    if(byte == 0xCC) // INT3
                        return rip + 1;
                    else if(byte == 0xCD) // INT with byte immediate
                        return rip + 2;
                    else if(byte == 0x0F) // two byte opcode prefix
                        twoByteOpcode = true;
                    else
                        return 0;
                }
            }
            buf >>= 8;
            rip++;
        }
    }
}

bool AMD64TraceChild::step()
{
    uint64_t ripAfterSyscall = findSyscall();
    if(ripAfterSyscall)
    {
        //Get the original contents of memory
        uint64_t buf = ptrace(PTRACE_PEEKDATA, pid, ripAfterSyscall, 0);
        //Patch the first two bytes of the memory immediately after this with
        //jmp -2. Either single stepping will take over before this
        //instruction, leaving the rip where it should be, or it will take
        //over after this instruction, -still- leaving the rip where it should
        //be.
        uint64_t newBuf = (buf & ~0xFFFF) | 0xFEEB;
        //Write the patched memory to the processes address space
        ptrace(PTRACE_POKEDATA, pid, ripAfterSyscall, newBuf);
        //Step and hit it
        ptraceSingleStep();
        //Put things back to the way they started
        ptrace(PTRACE_POKEDATA, pid, ripAfterSyscall, buf);
    }
    else
        ptraceSingleStep();
}

TraceChild * genTraceChild()
{
        return new AMD64TraceChild;
}