1 | /* |
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2 | * zzuf - general purpose fuzzer |
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3 | * Copyright (c) 2002-2010 Sam Hocevar <sam@hocevar.net> |
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4 | * All Rights Reserved |
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5 | * |
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6 | * This program is free software. It comes without any warranty, to |
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7 | * the extent permitted by applicable law. You can redistribute it |
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8 | * and/or modify it under the terms of the Do What The Fuck You Want |
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9 | * To Public License, Version 2, as published by Sam Hocevar. See |
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10 | * http://sam.zoy.org/wtfpl/COPYING for more details. |
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11 | */ |
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12 | |
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13 | /* |
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14 | * myfork.c: launcher |
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15 | */ |
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16 | |
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17 | #include "config.h" |
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18 | |
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19 | #define _INCLUDE_POSIX_SOURCE /* for STDERR_FILENO on HP-UX */ |
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20 | |
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21 | #if defined HAVE_STDINT_H |
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22 | # include <stdint.h> |
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23 | #elif defined HAVE_INTTYPES_H |
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24 | # include <inttypes.h> |
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25 | #endif |
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26 | #include <stdio.h> |
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27 | #include <stdlib.h> |
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28 | #if defined HAVE_UNISTD_H |
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29 | # include <unistd.h> |
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30 | #endif |
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31 | #if defined HAVE_WINDOWS_H |
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32 | # include <windows.h> |
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33 | # include <imagehlp.h> |
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34 | # include <tlhelp32.h> |
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35 | #endif |
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36 | #include <string.h> |
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37 | #include <fcntl.h> /* for O_BINARY */ |
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38 | #if defined HAVE_SYS_RESOURCE_H |
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39 | # include <sys/resource.h> /* for RLIMIT_AS */ |
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40 | #endif |
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41 | |
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42 | #include "common.h" |
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43 | #include "opts.h" |
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44 | #include "random.h" |
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45 | #include "fd.h" |
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46 | #include "fuzz.h" |
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47 | #include "myfork.h" |
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48 | #include "md5.h" |
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49 | #include "timer.h" |
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50 | |
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51 | /* Handle old libtool versions */ |
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52 | #if !defined LT_OBJDIR |
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53 | # define LT_OBJDIR ".libs/" |
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54 | #endif |
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55 | |
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56 | #if defined RLIMIT_AS |
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57 | # define ZZUF_RLIMIT_MEM RLIMIT_AS |
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58 | #elif defined RLIMIT_VMEM |
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59 | # define ZZUF_RLIMIT_MEM RLIMIT_VMEM |
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60 | #elif defined RLIMIT_DATA |
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61 | # define ZZUF_RLIMIT_MEM RLIMIT_DATA |
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62 | #else |
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63 | # undef ZZUF_RLIMIT_MEM |
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64 | #endif |
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65 | |
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66 | #if defined RLIMIT_CPU |
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67 | # define ZZUF_RLIMIT_CPU RLIMIT_CPU |
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68 | #else |
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69 | # undef ZZUF_RLIMIT_CPU |
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70 | #endif |
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71 | |
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72 | static int run_process(struct child *child, struct opts *, int[][2]); |
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73 | |
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74 | #if defined HAVE_WINDOWS_H |
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75 | static void rep32(uint8_t *buf, void *addr); |
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76 | static int dll_inject(void *, void *, char const *); |
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77 | static intptr_t get_base_address(DWORD); |
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78 | static intptr_t get_entry_point_offset(char const *); |
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79 | #endif |
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80 | |
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81 | int myfork(struct child *child, struct opts *opts) |
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82 | { |
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83 | int pipes[3][2]; |
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84 | pid_t pid; |
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85 | int i; |
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86 | |
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87 | /* Prepare communication pipe */ |
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88 | for(i = 0; i < 3; i++) |
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89 | { |
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90 | int ret; |
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91 | #if defined HAVE_PIPE |
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92 | ret = pipe(pipes[i]); |
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93 | #elif defined HAVE__PIPE |
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94 | ret = _pipe(pipes[i], 512, _O_BINARY | O_NOINHERIT); |
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95 | #endif |
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96 | if(ret < 0) |
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97 | { |
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98 | perror("pipe"); |
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99 | return -1; |
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100 | } |
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101 | } |
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102 | |
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103 | pid = run_process(child, opts, pipes); |
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104 | if(pid < 0) |
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105 | { |
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106 | /* FIXME: close pipes */ |
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107 | fprintf(stderr, "error launching `%s'\n", child->newargv[0]); |
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108 | return -1; |
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109 | } |
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110 | |
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111 | child->pid = pid; |
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112 | for(i = 0; i < 3; i++) |
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113 | { |
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114 | close(pipes[i][1]); |
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115 | child->fd[i] = pipes[i][0]; |
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116 | } |
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117 | |
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118 | return 0; |
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119 | } |
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120 | |
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121 | #if !defined HAVE_SETENV |
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122 | static void setenv(char const *name, char const *value, int overwrite) |
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123 | { |
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124 | char *str; |
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125 | |
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126 | if(!overwrite && getenv(name)) |
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127 | return; |
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128 | |
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129 | str = malloc(strlen(name) + 1 + strlen(value) + 1); |
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130 | sprintf(str, "%s=%s", name, value); |
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131 | putenv(str); |
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132 | } |
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133 | #endif |
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134 | |
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135 | static int run_process(struct child *child, struct opts *opts, int pipes[][2]) |
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136 | { |
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137 | char buf[64]; |
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138 | #if defined HAVE_FORK |
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139 | static int const files[] = { DEBUG_FILENO, STDERR_FILENO, STDOUT_FILENO }; |
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140 | char *libpath, *tmp; |
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141 | int pid, j, len = strlen(opts->oldargv[0]); |
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142 | # if defined __APPLE__ |
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143 | # define EXTRAINFO "" |
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144 | # define PRELOAD "DYLD_INSERT_LIBRARIES" |
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145 | setenv("DYLD_FORCE_FLAT_NAMESPACE", "1", 1); |
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146 | # elif defined __osf__ |
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147 | # define EXTRAINFO ":DEFAULT" |
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148 | # define PRELOAD "_RLD_LIST" |
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149 | # elif defined __sun && defined __i386 |
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150 | # define EXTRAINFO "" |
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151 | # define PRELOAD "LD_PRELOAD_32" |
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152 | # else |
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153 | # define EXTRAINFO "" |
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154 | # define PRELOAD "LD_PRELOAD" |
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155 | # endif |
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156 | #elif HAVE_WINDOWS_H |
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157 | PROCESS_INFORMATION pinfo; |
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158 | STARTUPINFO sinfo; |
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159 | HANDLE pid; |
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160 | void *epaddr; |
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161 | int ret; |
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162 | #endif |
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163 | |
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164 | #if defined HAVE_FORK |
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165 | /* Fork and launch child */ |
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166 | pid = fork(); |
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167 | if(pid < 0) |
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168 | perror("fork"); |
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169 | if(pid != 0) |
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170 | return pid; |
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171 | |
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172 | /* We loop in reverse order so that files[0] is done last, |
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173 | * just in case one of the other dup2()ed fds had the value */ |
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174 | for(j = 3; j--; ) |
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175 | { |
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176 | close(pipes[j][0]); |
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177 | if(pipes[j][1] != files[j]) |
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178 | { |
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179 | dup2(pipes[j][1], files[j]); |
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180 | close(pipes[j][1]); |
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181 | } |
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182 | } |
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183 | #endif |
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184 | |
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185 | #if defined HAVE_SETRLIMIT && defined ZZUF_RLIMIT_MEM |
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186 | if(opts->maxmem >= 0) |
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187 | { |
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188 | struct rlimit rlim; |
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189 | rlim.rlim_cur = opts->maxmem * 1048576; |
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190 | rlim.rlim_max = opts->maxmem * 1048576; |
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191 | setrlimit(ZZUF_RLIMIT_MEM, &rlim); |
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192 | } |
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193 | #endif |
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194 | |
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195 | #if defined HAVE_SETRLIMIT && defined ZZUF_RLIMIT_CPU |
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196 | if(opts->maxcpu >= 0) |
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197 | { |
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198 | struct rlimit rlim; |
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199 | rlim.rlim_cur = opts->maxcpu; |
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200 | rlim.rlim_max = opts->maxcpu + 5; |
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201 | setrlimit(ZZUF_RLIMIT_CPU, &rlim); |
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202 | } |
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203 | #endif |
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204 | |
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205 | /* Set environment variables */ |
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206 | sprintf(buf, "%i", opts->seed); |
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207 | setenv("ZZUF_SEED", buf, 1); |
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208 | sprintf(buf, "%g", opts->minratio); |
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209 | setenv("ZZUF_MINRATIO", buf, 1); |
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210 | sprintf(buf, "%g", opts->maxratio); |
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211 | setenv("ZZUF_MAXRATIO", buf, 1); |
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212 | |
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213 | #if defined HAVE_FORK |
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214 | /* Make sure there is space for everything we might do. */ |
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215 | libpath = malloc(len + strlen(LIBDIR "/" LT_OBJDIR SONAME EXTRAINFO) + 1); |
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216 | strcpy(libpath, opts->oldargv[0]); |
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217 | |
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218 | /* If the binary name contains a '/', we look for a libzzuf in the |
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219 | * same directory. Otherwise, we only look into the system directory |
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220 | * to avoid shared library attacks. Write the result in libpath. */ |
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221 | tmp = strrchr(libpath, '/'); |
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222 | if(tmp) |
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223 | { |
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224 | strcpy(tmp + 1, LT_OBJDIR SONAME); |
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225 | if(access(libpath, R_OK) < 0) |
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226 | strcpy(libpath, LIBDIR "/" SONAME); |
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227 | } |
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228 | else |
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229 | strcpy(libpath, LIBDIR "/" SONAME); |
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230 | |
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231 | /* OSF1 only */ |
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232 | strcat(libpath, EXTRAINFO); |
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233 | |
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234 | /* Do not clobber previous LD_PRELOAD values */ |
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235 | tmp = getenv(PRELOAD); |
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236 | if(tmp && *tmp) |
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237 | { |
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238 | char *bigbuf = malloc(strlen(tmp) + strlen(libpath) + 2); |
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239 | sprintf(bigbuf, "%s:%s", tmp, libpath); |
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240 | free(libpath); |
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241 | libpath = bigbuf; |
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242 | } |
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243 | |
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244 | /* Only preload the library in preload mode */ |
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245 | if (opts->opmode == OPMODE_PRELOAD) |
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246 | setenv(PRELOAD, libpath, 1); |
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247 | free(libpath); |
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248 | |
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249 | if(execvp(child->newargv[0], child->newargv)) |
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250 | { |
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251 | perror(child->newargv[0]); |
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252 | exit(EXIT_FAILURE); |
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253 | } |
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254 | |
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255 | exit(EXIT_SUCCESS); |
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256 | /* no return */ |
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257 | return 0; |
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258 | #elif HAVE_WINDOWS_H |
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259 | pid = GetCurrentProcess(); |
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260 | |
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261 | memset(&sinfo, 0, sizeof(sinfo)); |
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262 | sinfo.cb = sizeof(sinfo); |
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263 | DuplicateHandle(pid, (HANDLE)_get_osfhandle(pipes[0][1]), pid, |
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264 | /* FIXME */ &sinfo.hStdInput, 0, TRUE, DUPLICATE_SAME_ACCESS); |
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265 | DuplicateHandle(pid, (HANDLE)_get_osfhandle(pipes[1][1]), pid, |
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266 | &sinfo.hStdError, 0, TRUE, DUPLICATE_SAME_ACCESS); |
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267 | DuplicateHandle(pid, (HANDLE)_get_osfhandle(pipes[2][1]), pid, |
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268 | &sinfo.hStdOutput, 0, TRUE, DUPLICATE_SAME_ACCESS); |
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269 | sinfo.dwFlags = STARTF_USESTDHANDLES; |
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270 | ret = CreateProcess(NULL, child->newargv[0], NULL, NULL, FALSE, |
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271 | CREATE_SUSPENDED, NULL, NULL, &sinfo, &pinfo); |
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272 | if(!ret) |
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273 | return -1; |
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274 | |
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275 | /* Get the child process's entry point address */ |
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276 | epaddr = (void *)get_entry_point(child->newargv[0], |
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277 | pinfo.dwProcessId); |
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278 | if(!epaddr) |
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279 | return -1; |
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280 | |
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281 | /* Insert the replacement code */ |
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282 | ret = dll_inject(pinfo.hProcess, epaddr, SONAME); |
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283 | if(ret < 0) |
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284 | { |
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285 | TerminateProcess(pinfo.hProcess, -1); |
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286 | return -1; |
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287 | } |
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288 | |
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289 | ret = ResumeThread(pinfo.hThread); |
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290 | if(ret < 0) |
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291 | { |
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292 | TerminateProcess(pinfo.hProcess, -1); |
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293 | return -1; |
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294 | } |
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295 | |
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296 | return (long int)pinfo.hProcess; |
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297 | #endif |
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298 | } |
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299 | |
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300 | #if defined HAVE_WINDOWS_H |
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301 | static void rep32(uint8_t *buf, void *addr) |
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302 | { |
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303 | while(buf++) |
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304 | if (memcmp(buf, "____", 4) == 0) |
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305 | { |
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306 | memcpy(buf, &addr, 4); |
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307 | return; |
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308 | } |
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309 | } |
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310 | |
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311 | static int dll_inject(void *process, void *epaddr, char const *lib) |
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312 | { |
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313 | static uint8_t const loader[] = |
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314 | /* Load the injected DLL into memory */ |
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315 | "\xb8____" /* mov %eax, <library_name_address> */ |
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316 | "\x50" /* push %eax */ |
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317 | "\xb8____" /* mov %eax, <LoadLibraryA> */ |
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318 | "\xff\xd0" /* call %eax */ |
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319 | /* Restore the clobbered entry point code using our backup */ |
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320 | "\xb8\0\0\0\0" /* mov %eax,0 */ |
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321 | "\x50" /* push %eax */ |
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322 | "\xb8____" /* mov %eax, <jumper_length> */ |
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323 | "\x50" /* push %eax */ |
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324 | "\xb8____" /* mov %eax, <backuped_entry_point_address> */ |
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325 | "\x50" /* push %eax */ |
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326 | "\xb8____" /* mov %eax, <original_entry_point_address> */ |
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327 | "\x50" /* push %eax */ |
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328 | "\xb8____" /* mov %eax, <GetCurrentProcess> */ |
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329 | "\xff\xd0" /* call %eax */ |
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330 | "\x50" /* push %eax */ |
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331 | "\xb8____" /* mov %eax, <WriteProcessMemory> */ |
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332 | "\xff\xd0" /* call %eax */ |
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333 | /* Jump to the original entry point */ |
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334 | "\xb8____" /* mov %eax, <original_entry_point_address> */ |
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335 | "\xff\xe0"; /* jmp %eax */ |
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336 | |
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337 | static uint8_t const jumper[] = |
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338 | /* Jump to the injected loader */ |
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339 | "\xb8____" /* mov eax, <loader_address> */ |
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340 | "\xff\xe0"; /* jmp eax */ |
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341 | |
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342 | /* code: |
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343 | * +---------------+--------------------+--------------+-------------+ |
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344 | * | loader | entry point backup | library name | jumper | |
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345 | * | len(loader) | len(jumper) | len(lib) | len(jumper) | |
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346 | * +---------------+--------------------+--------------+-------------+ */ |
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347 | uint8_t code[1024]; |
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348 | |
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349 | void *kernel32; |
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350 | uint8_t *loaderaddr; |
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351 | size_t liblen, loaderlen, jumperlen; |
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352 | DWORD tmp; |
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353 | |
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354 | liblen = strlen(lib) + 1; |
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355 | loaderlen = sizeof(loader) - 1; |
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356 | jumperlen = sizeof(jumper) - 1; |
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357 | if (loaderlen + jumperlen + liblen > 1024) |
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358 | return -1; |
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359 | |
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360 | /* Allocate memory in the child for our injected code */ |
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361 | loaderaddr = VirtualAllocEx(process, NULL, loaderlen + jumperlen + liblen, |
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362 | MEM_COMMIT, PAGE_EXECUTE_READWRITE); |
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363 | if(!loaderaddr) |
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364 | return -1; |
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365 | |
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366 | /* Create the first shellcode (jumper). |
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367 | * |
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368 | * The jumper's job is simply to jump at the second shellcode's location. |
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369 | * It is written at the original entry point's location, which will in |
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370 | * turn be restored by the second shellcode. |
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371 | */ |
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372 | memcpy(code + loaderlen + jumperlen + liblen, jumper, jumperlen); |
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373 | rep32(code + loaderlen + jumperlen + liblen, loaderaddr); |
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374 | |
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375 | /* Create the second shellcode (loader, backuped entry point, and library |
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376 | * name). |
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377 | * |
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378 | * The loader's job is to load the library by calling LoadLibraryA(), |
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379 | * restore the original entry point using the backup copy, and jump |
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380 | * back to the original entry point as if the process had just started. |
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381 | * |
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382 | * The second shellcode is written at a freshly allocated memory location. |
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383 | */ |
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384 | memcpy(code, loader, loaderlen); |
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385 | memcpy(code + loaderlen + jumperlen, lib, liblen); |
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386 | |
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387 | /* Backup the old entry point code */ |
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388 | ReadProcessMemory(process, epaddr, code + loaderlen, |
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389 | jumperlen, &tmp); |
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390 | if(tmp != jumperlen) |
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391 | return -1; |
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392 | |
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393 | /* FIXME: the GetProcAddress calls assume the library was loaded at |
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394 | * the same address in the child process. This is wrong since Vista |
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395 | * and its address space randomisation. */ |
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396 | kernel32 = LoadLibrary("kernel32.dll"); |
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397 | if(!kernel32) |
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398 | return -1; |
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399 | |
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400 | rep32(code, loaderaddr + loaderlen + jumperlen); |
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401 | rep32(code, GetProcAddress(kernel32, "LoadLibraryA")); |
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402 | rep32(code, (void *)(uintptr_t)jumperlen); |
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403 | rep32(code, loaderaddr + loaderlen); |
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404 | rep32(code, epaddr); |
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405 | rep32(code, GetProcAddress(kernel32, "GetCurrentProcess")); |
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406 | rep32(code, GetProcAddress(kernel32, "WriteProcessMemory")); |
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407 | rep32(code, epaddr); |
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408 | FreeLibrary(kernel32); |
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409 | |
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410 | /* Write our shellcodes into the target process */ |
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411 | WriteProcessMemory(process, epaddr, code + loaderlen + jumperlen + liblen, |
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412 | jumperlen, &tmp); |
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413 | if(tmp != jumperlen) |
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414 | return -1; |
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415 | |
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416 | WriteProcessMemory(process, loaderaddr, code, |
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417 | loaderlen + jumperlen + liblen, &tmp); |
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418 | if(tmp != loaderlen + jumperlen + liblen) |
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419 | return -1; |
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420 | |
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421 | return 0; |
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422 | } |
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423 | |
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424 | /* Find the process's entry point address offset. The information is in |
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425 | * the file's PE header. */ |
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426 | static intptr_t get_entry_point(char const *name, DWORD pid) |
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427 | { |
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428 | PIMAGE_DOS_HEADER dos; |
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429 | PIMAGE_NT_HEADERS nt; |
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430 | intptr_t ret = 0; |
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431 | void *file, *map, *base; |
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432 | |
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433 | file = CreateFile(name, GENERIC_READ, FILE_SHARE_READ, |
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434 | NULL, OPEN_EXISTING, 0, NULL); |
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435 | if(file == INVALID_HANDLE_VALUE) |
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436 | return ret; |
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437 | |
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438 | map = CreateFileMapping(file, NULL, PAGE_READONLY, 0, 0, NULL); |
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439 | if(!map) |
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440 | { |
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441 | CloseHandle(file); |
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442 | return ret; |
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443 | } |
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444 | |
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445 | base = MapViewOfFile(map, FILE_MAP_READ, 0, 0, 0); |
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446 | if(!base) |
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447 | { |
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448 | CloseHandle(map); |
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449 | CloseHandle(file); |
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450 | return ret; |
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451 | } |
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452 | |
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453 | /* Sanity checks */ |
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454 | dos = (PIMAGE_DOS_HEADER)base; |
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455 | nt = (PIMAGE_NT_HEADERS)((char *)base + dos->e_lfanew); |
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456 | if(dos->e_magic == IMAGE_DOS_SIGNATURE /* 0x5A4D */ |
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457 | && nt->Signature == IMAGE_NT_SIGNATURE /* 0x00004550 */ |
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458 | && nt->FileHeader.Machine == IMAGE_FILE_MACHINE_I386 |
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459 | && nt->OptionalHeader.Magic == 0x10b /* IMAGE_NT_OPTIONAL_HDR32_MAGIC */) |
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460 | { |
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461 | ret = get_base_address(pid); |
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462 | /* Base address not found in the running process. Falling back |
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463 | * to the header's information, which is unreliable because of |
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464 | * Vista's address space randomisation. */ |
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465 | if (!ret) |
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466 | ret = (intptr_t)nt->OptionalHeader.BaseOfCode; |
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467 | |
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468 | ret += (intptr_t)nt->OptionalHeader.AddressOfEntryPoint; |
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469 | } |
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470 | |
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471 | UnmapViewOfFile(base); |
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472 | CloseHandle(map); |
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473 | CloseHandle(file); |
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474 | |
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475 | return ret; |
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476 | } |
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477 | |
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478 | /* Find the process's base address once it is loaded in memory (the header |
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479 | * information is unreliable because of Vista's ASLR). */ |
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480 | static intptr_t get_base_address(DWORD pid) |
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481 | { |
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482 | MODULEENTRY32 entry; |
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483 | intptr_t ret = 0; |
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484 | void *list; |
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485 | int k; |
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486 | |
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487 | list = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, pid); |
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488 | entry.dwSize = sizeof(entry); |
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489 | for(k = Module32First(list, &entry); k; k = Module32Next(list, &entry)) |
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490 | { |
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491 | /* FIXME: how do we select the correct module? */ |
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492 | ret = (intptr_t)entry.modBaseAddr; |
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493 | } |
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494 | CloseHandle(list); |
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495 | |
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496 | return ret; |
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497 | } |
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498 | |
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499 | #endif |
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