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1 #include <sys/stat.h>
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2 #include <sys/types.h>
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3 #include <unistd.h>
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4 #include <stdio.h>
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5 #include <errno.h>
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6 #include <stdlib.h>
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7 #include <pwd.h>
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8 #include <grp.h> // declares struct group
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9 #include <libgen.h> // for dirname
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10 #include <string.h> // for strcpy
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11
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12 /* cpy.c David Hoover 1/20/12
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13 usage:
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14 cpy from.file to.file login
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15
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16 cpy copies a file from one location to another, and then sets the ownership to a given user. The
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17 program is expected to be setuid and owned by root.
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18
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19 */
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20
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21 int notWriteable(char *file, char *user)
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22 /* Returns 1 if file not writeable by given user */
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23 {
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24 struct stat fileStat;
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25 struct passwd *own,*usr;
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26 struct group *grp;
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27 int i=0;
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28
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29 usr = getpwnam(user);
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30
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31 /* does user exist? */
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32 if (! usr)
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33 {
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34 fprintf(stderr,"%s: No such user\n",user);
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35 exit(1);
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36 }
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37
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38 /* must be able to stat file */
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39 if (stat(file, &fileStat) < 0)
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40 {
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41 fprintf(stderr,"%s: No such directory\n",file);
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42 exit(1);
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43 }
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44
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45 /* get the owner and group information for the file */
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46 own = getpwuid(fileStat.st_uid);
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47 grp = getgrgid(fileStat.st_gid);
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48
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49 /* does the file owner match the argument? */
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50 // if (!strcmp(own->pw_name,user))
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51 if (usr->pw_uid == fileStat.st_uid)
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52 {
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53 // printf("owners match!\n");
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54
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55 /* is file writeable? */
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56 if (fileStat.st_mode & S_IWUSR)
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57 {
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58 // printf("%s is writeable by %s\n",file,user);
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59 return 0;
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60 }
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61 else
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62 {
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63 // printf("%s is not writeable by %s\n",file,user);
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64 }
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65 }
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66 else {
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67 // printf("owners don't match!\n");
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68 }
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69
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70 /* is the file group readable by the given group? */
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71 if (fileStat.st_mode & S_IWGRP)
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72 {
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73 // printf("%s is writeable by group %s\n",file,grp->gr_name);
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74
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75
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76 /* is the user's gid the same as the file? */
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77 // printf("%d\n",usr->pw_gid);
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78 // printf("%d\n",fileStat.st_gid);
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79 if (usr->pw_gid == fileStat.st_gid)
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80 {
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81 // printf("groups match!\n");
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82
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83 /* if the path a directory is it executable? */
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84 if (S_ISDIR(fileStat.st_mode))
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85 {
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86 if (fileStat.st_mode & S_IXGRP)
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87 {
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88 return 0;
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89 }
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90 }
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91 else {
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92 return 0;
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93 }
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94 }
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95 else
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96 {
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97
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98 /* is the user a member of the group that owns the file? */
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99 while(grp->gr_mem[i] != NULL)
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100 {
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101 if(!strcmp(grp->gr_mem[i],user))
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102 {
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103 // printf("%s is a member of the %s group\n",user,grp->gr_name);
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104 /* if the path a directory is it executable? */
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105 if (S_ISDIR(fileStat.st_mode))
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106 {
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107 if (fileStat.st_mode & S_IXGRP)
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108 {
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109 return 0;
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110 }
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111 }
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112 else {
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113 return 0;
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114 }
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115 }
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116 i++;
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117 }
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118
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119 // printf("%s is not a member of the %s group\n",user,grp->gr_name);
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120
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121 }
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122 }
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123 else
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124 {
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125 // printf("%s is not writeable by group %s\n",file,grp->gr_name);
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126 }
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127
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128 /* is the e world writeable? */
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129 if (fileStat.st_mode & S_IWOTH)
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130 {
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131 // printf("%s is world writeable\n",file);
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132 return 0;
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133 }
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134 else
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135 {
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136 // printf("%s is not world writeable\n",file);
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137 }
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138
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139 return 1;
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140 }
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141
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142 int notReadable(char *file, char *user)
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143 /* Returns 1 if file not readable by given user */
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144 {
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145 struct stat fileStat;
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146 struct passwd *own,*usr;
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147 struct group *grp;
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148 int i=0;
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149
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150 usr = getpwnam(user);
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151
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152 /* does user exist? */
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153 if (! usr)
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154 {
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155 fprintf(stderr,"%s: No such user\n",user);
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156 exit(1);
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157 }
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158
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159 /* must be able to stat file */
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160 if (stat(file, &fileStat) < 0)
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161 {
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162 fprintf(stderr,"%s: No such directory\n",file);
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163 exit(1);
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164 }
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165
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166 /* get the owner and group information for the file */
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167 own = getpwuid(fileStat.st_uid);
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168 grp = getgrgid(fileStat.st_gid);
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169
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170 /* does the file owner match the argument? */
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171 // if (!strcmp(own->pw_name,user))
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172 if (usr->pw_uid == fileStat.st_uid)
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173 {
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174 // printf("owners match!\n");
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175
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176 /* is file readable? */
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177 if (fileStat.st_mode & S_IRUSR)
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178 {
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179 // printf("%s is readable by %s\n",file,user);
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180 return 0;
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181 }
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182 else
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183 {
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184 // printf("%s is not readable by %s\n",file,user);
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185 }
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186 }
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187 else {
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188 // printf("owners don't match!\n");
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189 }
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190
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191 /* is the file group readable by the given group? */
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192 if (fileStat.st_mode & S_IRGRP)
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193 {
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194 // printf("%s is readable by group %s\n",file,grp->gr_name);
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195
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196
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197 /* is the user's gid the same as the file? */
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198 // printf("%d\n",usr->pw_gid);
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199 // printf("%d\n",fileStat.st_gid);
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200 if (usr->pw_gid == fileStat.st_gid)
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201 {
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202 // printf("groups match!\n");
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203
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204 /* if the path a directory is it executable? */
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205 if (S_ISDIR(fileStat.st_mode))
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206 {
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207 if (fileStat.st_mode & S_IXGRP)
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208 {
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209 return 0;
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210 }
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211 }
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212 else {
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213 return 0;
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214 }
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215 }
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216 else
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217 {
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218
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219 /* is the user a member of the group that owns the file? */
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220 while(grp->gr_mem[i] != NULL)
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221 {
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222 if(!strcmp(grp->gr_mem[i],user))
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223 {
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224 // printf("%s is a member of the %s group\n",user,grp->gr_name);
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225 /* if the path a directory is it executable? */
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226 if (S_ISDIR(fileStat.st_mode))
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227 {
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228 if (fileStat.st_mode & S_IXGRP)
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229 {
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230 return 0;
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231 }
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232 }
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233 else {
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234 return 0;
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235 }
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236 }
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237 i++;
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238 }
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239
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240 // printf("%s is not a member of the %s group\n",user,grp->gr_name);
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241
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242 }
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243 }
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244 else
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245 {
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246 // printf("%s is not readable by group %s\n",file,grp->gr_name);
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247 }
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248
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249 /* is the e world readable? */
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250 if (fileStat.st_mode & S_IROTH)
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251 {
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252 // printf("%s is world readable\n",file);
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253 return 0;
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254 }
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255 else
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256 {
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257 // printf("%s is not world readable\n",file);
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258 }
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259
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260 return 1;
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261 }
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262
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263 int copyFile(char *src, char *dst)
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264 {
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265 // printf("Copying %s to %s\n",src,dst);
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266
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267 int c;
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268 FILE *fs,*ft;
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269 struct stat fileStat;
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270
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271 /* must be able to stat file */
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272 if (stat(src, &fileStat) < 0)
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273 {
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274 fprintf(stderr,"%s: No such file\n",src);
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275 exit(1);
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276 }
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277
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278 /* is path a regular file? */
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279 if (S_ISDIR(fileStat.st_mode))
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280 {
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281 fprintf(stderr,"%s: Is a directory\n",src);
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282 exit(1);
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283 }
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284
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285 fs = fopen(src,"r");
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286 if (fs==NULL) {
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287 fprintf(stderr,"Can't read from file %s!\n",src);
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288 exit(1);
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289 }
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290 ft = fopen(dst,"w");
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291 if (ft==NULL) {
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292 fprintf(stderr,"Can't write to file %s!\n",dst);
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293 exit(1);
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294 }
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295
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296 c = getc(fs);
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297 while (c != EOF) {
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298 putc(c,ft);
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299 c = getc(fs);
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300 }
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301
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302 fclose(fs);
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303 fclose(ft);
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304
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305 return 0;
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306
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307 }
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308
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309 int chownToGivenUser(char *file, char *user)
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310 /* chown a file to the given user */
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311 {
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312 struct passwd *usr;
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313
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314 usr = getpwnam(user);
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315
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316 // printf("UID = %d\n",usr->pw_uid);
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317 // printf("GID = %d\n",usr->pw_gid);
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318
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319 // printf("chown %s %d,%d\n",file,usr->pw_uid,usr->pw_gid);
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320 if (chown(file,usr->pw_uid,usr->pw_gid))
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321 {
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322 fprintf(stderr,"Can't chown %s\n",file);
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323 exit(1);
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324 }
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325 return 0;
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326 }
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327
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328 int explodePath(char *file, char *user)
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329 /* Returns 1 if file not readable by given user */
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330 {
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331 char **path;
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332 char *dir;
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333 char newfile[10000];
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334 int i;
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335
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336 strcpy(newfile,file);
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337 if (!notReadable(newfile,user))
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338 {
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339 dir = dirname(newfile);
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340 if (strcmp(dir,"/"))
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341 explodePath(dir,user);
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342 }
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343 else
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344 {
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345 fprintf(stderr,"%s: Permission denied.\n",file);
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346 exit(1);
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347 }
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348
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349 return 0;
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350 }
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351
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352 main(int argc, char **argv)
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353 {
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354 char *dir;
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355 char newfile[10000];
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356 struct stat fileStat;
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357
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358 /* must have two arguments */
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359 if (argc != 4)
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360 {
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361 fprintf(stderr,"usage: cpy source dest user\n");
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362 exit(1);
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363 }
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364
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365 /* is filepath writeable by given user? */
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366 strcpy(newfile,argv[2]);
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367 dir = dirname(newfile);
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368 if (!notWriteable(dir,argv[3]))
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369 {
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370
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371 /* is filepath readable by given user? */
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372 explodePath(dir,argv[3]);
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373
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374 /* dest file must not exist yet */
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375 if (!(stat(argv[2], &fileStat) < 0))
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376 {
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377 fprintf(stderr,"%s: File already exists.\n",argv[2]);
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378 exit(1);
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379 }
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380
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381 /* copy the file and change the owner */
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382 copyFile(argv[1],argv[2]);
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383 chownToGivenUser(argv[2],argv[3]);
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384 }
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385 else
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386 {
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387 fprintf(stderr,"%s: Permission denied.\n",argv[2]);
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388 exit(1);
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389 }
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390
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391 exit(0);
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392 }
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