1 | /* |
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2 | * Copyright (c) 1997-2003 Red Hat, Inc. All rights reserved. |
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3 | * |
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4 | * This program is free software; you can redistribute it and/or modify |
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5 | * it under the terms of the GNU General Public License, version 2, |
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6 | * as published by the Free Software Foundation. |
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7 | * |
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8 | * This program is distributed in the hope that it will be useful, |
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9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 | * GNU General Public License for more details. |
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12 | * |
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13 | * You should have received a copy of the GNU General Public License |
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14 | * along with this program; if not, write to the Free Software |
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15 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
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16 | * |
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17 | */ |
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18 | |
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19 | #include <alloca.h> |
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20 | #include <ctype.h> |
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21 | #include <errno.h> |
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22 | #include <fcntl.h> |
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23 | #include <stdio.h> |
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24 | #include <stdlib.h> |
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25 | #include <string.h> |
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26 | #include <sys/stat.h> |
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27 | #include <unistd.h> |
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28 | #include <limits.h> |
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29 | |
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30 | /* This will be running setuid root, so be careful! */ |
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31 | static const char * safeEnviron[] = { |
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32 | "PATH=/bin:/sbin:/usr/bin:/usr/sbin", |
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33 | "HOME=/root", |
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34 | NULL |
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35 | }; |
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36 | |
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37 | #define FOUND_FALSE -1 |
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38 | #define NOT_FOUND 0 |
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39 | #define FOUND_TRUE 1 |
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40 | |
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41 | static void |
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42 | usage(void) { |
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43 | fprintf(stderr, "usage: usernetctl <interface-config> <up|down|report>\n"); |
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44 | exit(1); |
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45 | } |
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46 | |
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47 | static size_t |
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48 | testSafe(char *ifaceConfig, int fd) { |
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49 | struct stat sb; |
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50 | |
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51 | /* These shouldn't be symbolic links -- anal, but that's fine w/ mkj. */ |
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52 | if (fstat(fd, &sb)) { |
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53 | fprintf(stderr, "failed to stat %s: %s\n", ifaceConfig, |
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54 | strerror(errno)); |
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55 | exit(1); |
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56 | } |
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57 | |
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58 | /* Safety/sanity checks. */ |
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59 | if (!S_ISREG(sb.st_mode)) { |
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60 | fprintf(stderr, "%s is not a normal file\n", ifaceConfig); |
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61 | exit(1); |
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62 | } |
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63 | |
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64 | if (sb.st_uid) { |
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65 | fprintf(stderr, "%s should be owned by root\n", ifaceConfig); |
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66 | exit(1); |
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67 | } |
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68 | |
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69 | if (sb.st_mode & S_IWOTH) { |
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70 | fprintf(stderr, "%s should not be world writeable\n", ifaceConfig); |
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71 | exit(1); |
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72 | } |
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73 | |
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74 | return sb.st_size; |
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75 | } |
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76 | |
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77 | |
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78 | static int |
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79 | userCtl(char *file) { |
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80 | char *buf; |
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81 | char *contents = NULL; |
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82 | char *chptr = NULL; |
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83 | char *next = NULL; |
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84 | int fd = -1, retval = NOT_FOUND; |
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85 | size_t size = 0; |
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86 | |
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87 | /* Open the file and then test it to see if we like it. This way |
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88 | we avoid switcheroo attacks. */ |
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89 | if ((fd = open(file, O_RDONLY)) == -1) { |
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90 | fprintf(stderr, "failed to open %s: %s\n", file, strerror(errno)); |
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91 | exit(1); |
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92 | } |
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93 | |
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94 | size = testSafe(file, fd); |
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95 | if (size > INT_MAX) { |
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96 | fprintf(stderr, "file %s is too big\n", file); |
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97 | exit(1); |
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98 | } |
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99 | |
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100 | buf = contents = malloc(size + 2); |
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101 | if (contents == NULL) { |
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102 | fprintf(stderr, "failed to allocate memory\n"); |
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103 | exit(1); |
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104 | } |
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105 | |
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106 | if (read(fd, contents, size) != size) { |
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107 | perror("error reading device configuration"); |
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108 | exit(1); |
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109 | } |
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110 | close(fd); |
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111 | |
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112 | contents[size] = '\n'; |
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113 | contents[size + 1] = '\0'; |
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114 | |
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115 | /* Each pass parses a single line (until an answer is found), The contents |
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116 | pointer itself points to the beginning of the current line. */ |
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117 | while (*contents) { |
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118 | chptr = contents; |
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119 | while (*chptr != '\n') chptr++; |
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120 | next = chptr + 1; |
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121 | while (chptr >= contents && isspace(*chptr)) chptr--; |
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122 | *(++chptr) = '\0'; |
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123 | |
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124 | if (!strncasecmp(contents, "USERCTL=", 8)) { |
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125 | contents += 8; |
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126 | if ((contents[0] == '"' && |
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127 | contents[strlen(contents) - 1] == '"') || |
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128 | (contents[0] == '\'' && |
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129 | contents[strlen(contents) - 1] == '\'')) |
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130 | { |
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131 | contents++; |
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132 | contents[strlen(contents) - 1] = '\0'; |
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133 | } |
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134 | |
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135 | if (!strcasecmp(contents, "yes") || !strcasecmp(contents, "true")) |
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136 | retval = FOUND_TRUE; |
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137 | else |
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138 | retval = FOUND_FALSE; |
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139 | |
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140 | break; |
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141 | } |
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142 | |
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143 | contents = next; |
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144 | } |
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145 | |
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146 | free(buf); |
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147 | |
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148 | return retval; |
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149 | } |
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150 | |
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151 | int |
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152 | main(int argc, char ** argv) { |
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153 | char * ifaceConfig; |
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154 | char * chptr; |
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155 | char * cmd = NULL; |
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156 | int report = 0; |
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157 | char tmp; |
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158 | |
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159 | if (argc != 3) usage(); |
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160 | |
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161 | if (!strcmp(argv[2], "up")) { |
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162 | cmd = "./ifup"; |
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163 | } else if (!strcmp(argv[2], "down")) { |
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164 | cmd = "./ifdown"; |
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165 | } else if (!strcmp(argv[2], "report")) { |
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166 | report = 1; |
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167 | } else { |
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168 | usage(); |
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169 | } |
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170 | |
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171 | if (chdir("/etc/sysconfig/network-scripts")) { |
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172 | fprintf(stderr, "error switching to /etc/sysconfig/network-scripts: " |
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173 | "%s\n", strerror(errno)); |
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174 | exit(1); |
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175 | } |
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176 | |
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177 | /* force the interface configuration to be in the current directory */ |
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178 | chptr = ifaceConfig = argv[1]; |
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179 | while (*chptr) { |
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180 | if (*chptr == '/') |
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181 | ifaceConfig = chptr + 1; |
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182 | chptr++; |
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183 | } |
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184 | |
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185 | /* automatically prepend "ifcfg-" if it is not specified */ |
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186 | if (strncmp(ifaceConfig, "ifcfg-", 6)) { |
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187 | char *temp; |
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188 | size_t len = strlen(ifaceConfig); |
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189 | |
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190 | /* Make sure a wise guys hasn't tried an integer wrap-around or |
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191 | stack overflow attack. There's no way it could refer to anything |
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192 | bigger than the largest filename, so cut 'em off there. */ |
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193 | if (len > PATH_MAX) |
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194 | exit(1); |
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195 | |
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196 | temp = (char *) alloca(len + 7); |
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197 | strcpy(temp, "ifcfg-"); |
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198 | /* strcat is safe because we got the length from strlen */ |
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199 | strcat(temp, ifaceConfig); |
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200 | ifaceConfig = temp; |
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201 | } |
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202 | |
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203 | if(getuid() != 0) |
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204 | switch (userCtl(ifaceConfig)) { |
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205 | char *dash; |
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206 | |
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207 | case NOT_FOUND: |
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208 | /* a `-' will be found at least in "ifcfg-" */ |
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209 | dash = strrchr(ifaceConfig, '-'); |
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210 | if (*(dash-1) != 'g') { |
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211 | /* This was a clone configuration; ask the parent config */ |
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212 | tmp = *dash; |
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213 | *dash = '\0'; |
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214 | if (userCtl(ifaceConfig) == FOUND_TRUE) { |
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215 | /* exit the switch; users are allowed to control */ |
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216 | *dash = tmp; |
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217 | break; |
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218 | } |
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219 | *dash = tmp; |
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220 | } |
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221 | /* else fall through */ |
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222 | case FOUND_FALSE: |
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223 | if (! report) |
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224 | fprintf(stderr, |
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225 | "Users are not allowed to control this interface.\n"); |
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226 | exit(1); |
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227 | break; |
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228 | } |
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229 | |
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230 | /* looks good to me -- let's go for it if we are changing the interface, |
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231 | * report good status to the user otherwise */ |
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232 | |
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233 | if (report) |
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234 | exit(0); |
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235 | |
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236 | /* pppd wants the real uid to be the same as the effective (god only |
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237 | knows why when it works fine setuid out of the box) */ |
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238 | setuid(geteuid()); |
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239 | /* Drop user gid (for temp files, SELinux) */ |
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240 | setgid(0); |
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241 | |
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242 | execle(cmd, cmd, ifaceConfig, NULL, safeEnviron); |
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243 | fprintf(stderr, "exec of %s failed: %s\n", cmd, strerror(errno)); |
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244 | |
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245 | exit(1); |
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246 | } |
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