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4 | |
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5 | SYNOPSIS |
5 | SYNOPSIS |
6 | -lptytty |
6 | -lptytty |
7 | |
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8 | DESCRIPTION |
8 | DESCRIPTION |
9 | THE ptytty CLASS |
9 | TODO |
10 | new ptytty |
10 | |
11 | ... |
11 | SECURITY CONSIDERATIONS |
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12 | *It is of paramount importance that you at least read the following |
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13 | paragraph!* |
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14 | |
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15 | If you are a typical terminal-like program that just wants one or more |
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16 | ptys, you should call the "ptytty::init ()" method (C: "ptytty_init ()" |
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17 | function) as the very first thing in your program: |
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18 | |
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19 | int main (int argc, char *argv[]) |
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20 | { |
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21 | // do nothing here |
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22 | ptytty::init (); |
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23 | // in C: ptytty_init (); |
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24 | |
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25 | // initialise, parse arguments, etc. |
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26 | } |
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27 | |
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28 | This checks wether the program runs setuid or setgid. If yes then it |
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29 | will fork a helper process and drop privileges. |
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30 | |
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31 | Some programs need finer control over if and when this helper process is |
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32 | started, and if and how to drop privileges. For those programs, the |
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33 | methods "ptytty::use_helper" and "ptytty::drop_privileges" are more |
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34 | useful. |
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35 | |
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36 | C++ INTERFACE: THE ptytty CLASS |
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37 | STATIC METHODS |
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38 | ptytty::init () |
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39 | The default way to initialise libptytty. Must be called imemdiately |
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40 | as the first thing in the "main" function, or earlier e.g. during |
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41 | static construction time. The earlier, the better. |
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42 | |
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43 | This method checks wether the program runs with setuid/setgid |
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44 | permissions and, if yes, spawns a helper process for pty/tty |
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45 | management. IT then drops the privileges completely, so the actual |
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46 | program runs without setuid/setgid privileges. |
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47 | |
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48 | ptytty::use_helper () |
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49 | Tries to start a helper process that retains privileges even when |
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50 | the calling process does not. This is usually called from |
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51 | "ptytty::init" when it detects that the program is running setuid or |
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52 | setgid, but can be called manually if it is inconvinient to drop |
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53 | privileges at startup, or when you are not running setuid/setgid but |
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54 | want to drop privileges (e.g. when running as a root-started |
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55 | daemon). |
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56 | |
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57 | This method will try not to start more than one helper process. The |
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58 | same helper process cna usually be used form the process starting it |
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59 | an all its fork'ed (not exec'ed) children |
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60 | |
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61 | ptytty::drop_privileges () |
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62 | Drops privileges completely, i.e. sets real, effective and saved |
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63 | user id to the real user id. Also aborts if this cnanot be achieved. |
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64 | Useful to make sure that the process doesn't run with special |
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65 | privileges. |
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66 | |
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67 | bool success = ptytty::send_fd (int socket, int fd) |
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68 | Utility method to send a file descriptor over a unix domain socket. |
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69 | Returns true if successful, false otherwise. This method is only |
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70 | exposed for your convinience and is not required for normal |
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71 | operation. |
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72 | |
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73 | int fd = ptytty::recv_fd (int socket) |
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74 | Utility method to receive a file descriptor over a unix domain |
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75 | socket. Returns the fd if sucecssful and -1 otherwise. This method |
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76 | is only exposed for your convinience and is not required for normal |
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77 | operation. |
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78 | |
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79 | ptytty *pty = ptytty::create () |
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80 | Creates new ptytty object. Creation does not yet do anything besides |
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81 | allocating the structure. |
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82 | |
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83 | A static method is used because the actual ptytty implementation can |
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84 | differ at runtime, so you need a dynamic object creation facility. |
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85 | |
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86 | DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS |
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87 | int pty_fd = pty->pty |
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88 | int tty_fd = pty->tty |
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89 | These members contain the pty and tty file descriptors, |
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90 | respectively. They initially contain -1 until a successful to |
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91 | "ptytty::get". |
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92 | |
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93 | bool success = pty->get () |
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94 | Tries to find, allocate and initialise a new pty/tty pair. Returns |
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95 | "true" when successful. |
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96 | |
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97 | pty->login (int cmd_pid, bool login_shell, const char *hostname) |
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98 | Creates an entry in the systems session database(s) (utmp, wtmp, |
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99 | lastlog). "cmd_pid" must be the pid of the process representing the |
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100 | session (such as the login shell), "login_shell" defines wether the |
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101 | session is associated with a login, which influences wether wtmp and |
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102 | lastlog entries are created, and "hostname" should identify the |
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103 | "hostname" the user logs in from, which often is the value of the |
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104 | "DISPLAY" variable or tty line in case of local logins. |
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105 | |
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106 | Calling this method is optional. A session starts at the time of the |
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107 | login call and extends until the ptytty object is destroyed. |
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108 | |
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109 | pty->close_tty () |
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110 | Closes the tty. Useful after forking in the parent/pty process. |
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111 | |
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112 | bool success = pty->make_controlling_tty () |
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113 | Tries to make the pty/tty pair the controlling terminal of the |
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114 | current process. Useful after forking in the child/tty process. |
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115 | |
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116 | pty->set_utf8_mode (bool on) |
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117 | On systems supporting special UTF-8 line disciplines (e.g. Linux), |
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118 | tries to enable it for the given pty. Can be called at any time to |
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119 | change the mode. |
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120 | |
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121 | C INTERFACE: THE ptytty FAMILY OF FUNCTIONS |
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122 | ptytty_init () |
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123 | See "ptytty::init ()". |
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124 | |
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125 | PTYTTY ptytty_create () |
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126 | Creates a new opaque PTYTTY object and returns it. Do not try to |
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127 | access it in any way excecp by testing it for truthness (e.g. "if |
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128 | (pty) ...."). See "ptytty::create ()". |
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129 | |
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130 | int ptytty_pty (PTYTTY ptytty) |
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131 | Return the pty file descriptor. See "pty->pty". |
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132 | |
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133 | int ptytty_tty (PTYTTY ptytty) |
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134 | Return the tty file descriptor. See "pty->tty". |
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135 | |
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136 | void ptytty_delete (PTYTTY ptytty) |
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137 | Destroys the PTYTTY object, freeing the pty/tty pair and cleaning up |
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138 | the utmp/wtmp/lastlog databases, if initialised/used. Same as |
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139 | "delete pty" in C++. |
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140 | |
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141 | int ptytty_get (PTYTTY ptytty) |
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142 | See "pty->get", returns 0 in case of an error, non-zero otherwise. |
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143 | |
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144 | void ptytty_login (PTYTTY ptytty, int cmd_pid, bool login_shell, const |
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145 | char *hostname) |
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146 | See "pty->login". |
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147 | |
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148 | void ptytty_close_tty (PTYTTY ptytty) |
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149 | See "pty->close_tty". |
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150 | |
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151 | int ptytty_make_controlling_tty (PTYTTY ptytty) |
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152 | See "pty->make_controlling_tty". |
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153 | |
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154 | void ptytty_set_utf8_mode (PTYTTY ptytty, int on) |
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155 | See "pty->set_utf8_mode". |
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156 | |
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157 | void ptytty_drop_privileges () |
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158 | See "ptytty::drop_privileges". |
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159 | |
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160 | void ptytty_use_helper () |
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161 | See "ptytty::use_helper". |
12 | |
162 | |
13 | BUGS |
163 | BUGS |
14 | You kiddin'? |
164 | You kiddin'? |
15 | |
165 | |
16 | AUTHORS |
166 | AUTHORS |