| 1 |
.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32 |
| 2 |
.\" |
| 3 |
.\" Standard preamble: |
| 4 |
.\" ======================================================================== |
| 5 |
.de Sh \" Subsection heading |
| 6 |
.br |
| 7 |
.if t .Sp |
| 8 |
.ne 5 |
| 9 |
.PP |
| 10 |
\fB\\$1\fR |
| 11 |
.PP |
| 12 |
.. |
| 13 |
.de Sp \" Vertical space (when we can't use .PP) |
| 14 |
.if t .sp .5v |
| 15 |
.if n .sp |
| 16 |
.. |
| 17 |
.de Vb \" Begin verbatim text |
| 18 |
.ft CW |
| 19 |
.nf |
| 20 |
.ne \\$1 |
| 21 |
.. |
| 22 |
.de Ve \" End verbatim text |
| 23 |
.ft R |
| 24 |
.fi |
| 25 |
.. |
| 26 |
.\" Set up some character translations and predefined strings. \*(-- will |
| 27 |
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
| 28 |
.\" double quote, and \*(R" will give a right double quote. | will give a |
| 29 |
.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to |
| 30 |
.\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' |
| 31 |
.\" expand to `' in nroff, nothing in troff, for use with C<>. |
| 32 |
.tr \(*W-|\(bv\*(Tr |
| 33 |
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
| 34 |
.ie n \{\ |
| 35 |
. ds -- \(*W- |
| 36 |
. ds PI pi |
| 37 |
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
| 38 |
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch |
| 39 |
. ds L" "" |
| 40 |
. ds R" "" |
| 41 |
. ds C` "" |
| 42 |
. ds C' "" |
| 43 |
'br\} |
| 44 |
.el\{\ |
| 45 |
. ds -- \|\(em\| |
| 46 |
. ds PI \(*p |
| 47 |
. ds L" `` |
| 48 |
. ds R" '' |
| 49 |
'br\} |
| 50 |
.\" |
| 51 |
.\" If the F register is turned on, we'll generate index entries on stderr for |
| 52 |
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
| 53 |
.\" entries marked with X<> in POD. Of course, you'll have to process the |
| 54 |
.\" output yourself in some meaningful fashion. |
| 55 |
.if \nF \{\ |
| 56 |
. de IX |
| 57 |
. tm Index:\\$1\t\\n%\t"\\$2" |
| 58 |
.. |
| 59 |
. nr % 0 |
| 60 |
. rr F |
| 61 |
.\} |
| 62 |
.\" |
| 63 |
.\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 64 |
.\" way too many mistakes in technical documents. |
| 65 |
.hy 0 |
| 66 |
.if n .na |
| 67 |
.\" |
| 68 |
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
| 69 |
.\" Fear. Run. Save yourself. No user-serviceable parts. |
| 70 |
. \" fudge factors for nroff and troff |
| 71 |
.if n \{\ |
| 72 |
. ds #H 0 |
| 73 |
. ds #V .8m |
| 74 |
. ds #F .3m |
| 75 |
. ds #[ \f1 |
| 76 |
. ds #] \fP |
| 77 |
.\} |
| 78 |
.if t \{\ |
| 79 |
. ds #H ((1u-(\\\\n(.fu%2u))*.13m) |
| 80 |
. ds #V .6m |
| 81 |
. ds #F 0 |
| 82 |
. ds #[ \& |
| 83 |
. ds #] \& |
| 84 |
.\} |
| 85 |
. \" simple accents for nroff and troff |
| 86 |
.if n \{\ |
| 87 |
. ds ' \& |
| 88 |
. ds ` \& |
| 89 |
. ds ^ \& |
| 90 |
. ds , \& |
| 91 |
. ds ~ ~ |
| 92 |
. ds / |
| 93 |
.\} |
| 94 |
.if t \{\ |
| 95 |
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" |
| 96 |
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' |
| 97 |
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' |
| 98 |
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' |
| 99 |
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' |
| 100 |
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' |
| 101 |
.\} |
| 102 |
. \" troff and (daisy-wheel) nroff accents |
| 103 |
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' |
| 104 |
.ds 8 \h'\*(#H'\(*b\h'-\*(#H' |
| 105 |
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] |
| 106 |
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' |
| 107 |
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' |
| 108 |
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] |
| 109 |
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] |
| 110 |
.ds ae a\h'-(\w'a'u*4/10)'e |
| 111 |
.ds Ae A\h'-(\w'A'u*4/10)'E |
| 112 |
. \" corrections for vroff |
| 113 |
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' |
| 114 |
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' |
| 115 |
. \" for low resolution devices (crt and lpr) |
| 116 |
.if \n(.H>23 .if \n(.V>19 \ |
| 117 |
\{\ |
| 118 |
. ds : e |
| 119 |
. ds 8 ss |
| 120 |
. ds o a |
| 121 |
. ds d- d\h'-1'\(ga |
| 122 |
. ds D- D\h'-1'\(hy |
| 123 |
. ds th \o'bp' |
| 124 |
. ds Th \o'LP' |
| 125 |
. ds ae ae |
| 126 |
. ds Ae AE |
| 127 |
.\} |
| 128 |
.rm #[ #] #H #V #F C |
| 129 |
.\" ======================================================================== |
| 130 |
.\" |
| 131 |
.IX Title "libptytty 3" |
| 132 |
.TH libptytty 3 "2006-08-30" "" "LIBPTYTTY" |
| 133 |
.SH "NAME" |
| 134 |
libptytty \- OS independent and secure pty/tty and utmp/wtmp/lastlog handling |
| 135 |
.SH "SYNOPSIS" |
| 136 |
.IX Header "SYNOPSIS" |
| 137 |
.Vb 1 |
| 138 |
\& cc ... -lptytty |
| 139 |
.Ve |
| 140 |
.PP |
| 141 |
.Vb 1 |
| 142 |
\& #include <libptytty.h> |
| 143 |
.Ve |
| 144 |
.PP |
| 145 |
.Vb 2 |
| 146 |
\& // C++ |
| 147 |
\& ptytty *pty = ptytty::create (); |
| 148 |
.Ve |
| 149 |
.PP |
| 150 |
.Vb 2 |
| 151 |
\& if (!pty->get ()) |
| 152 |
\& // error allocating pty |
| 153 |
.Ve |
| 154 |
.PP |
| 155 |
.Vb 4 |
| 156 |
\& if (we want utmp) |
| 157 |
\& pty->login (process_pid, 0, "remote.host"); |
| 158 |
\& else if (we want utmp AND wtmp/lastlog) |
| 159 |
\& pty->login (process_pid, 1, "remote.host"); |
| 160 |
.Ve |
| 161 |
.PP |
| 162 |
.Vb 2 |
| 163 |
\& // we are done with it |
| 164 |
\& delete pty; |
| 165 |
.Ve |
| 166 |
.PP |
| 167 |
.Vb 2 |
| 168 |
\& // C |
| 169 |
\& PTYTTY pty = ptytty_create (); |
| 170 |
.Ve |
| 171 |
.PP |
| 172 |
.Vb 2 |
| 173 |
\& if (!ptytty_get (pty)) |
| 174 |
\& // error allocating pty |
| 175 |
.Ve |
| 176 |
.PP |
| 177 |
.Vb 4 |
| 178 |
\& if (we want utmp) |
| 179 |
\& ptytty_login (pty, process_pid, 0, "remote.host"); |
| 180 |
\& else if (we want utmp AND wtmp/lastlog) |
| 181 |
\& ptytty_login (pty, process_pid, 1, "remote.host"); |
| 182 |
.Ve |
| 183 |
.PP |
| 184 |
.Vb 2 |
| 185 |
\& // we are done with it |
| 186 |
\& ptytty_delete (pty); |
| 187 |
.Ve |
| 188 |
.PP |
| 189 |
See also the \fIeg/\fR directory, which currently contains the \fIc\-sample.c\fR |
| 190 |
file that spawns a loginshell from C using libptytty. |
| 191 |
.SH "DESCRIPTION" |
| 192 |
.IX Header "DESCRIPTION" |
| 193 |
Libptytty is a small library that offers pseudo-tty management in an |
| 194 |
OS-independent way. It was created out of frustration over the many |
| 195 |
differences of pty/tty handling in different operating systems for the use |
| 196 |
inside \f(CW\*(C`rxvt\-unicode\*(C'\fR. |
| 197 |
.PP |
| 198 |
In addition to offering mere pty/tty management, it also offers session |
| 199 |
database support (utmp and optional wtmp/lastlog updates for login |
| 200 |
shells). |
| 201 |
.PP |
| 202 |
It also supports fork'ing after startup and dropping privileges in the |
| 203 |
calling process, so in case the calling process gets compromised by the |
| 204 |
user starting the program there is less to gain, as only the helper |
| 205 |
process runs with privileges (e.g. setuid/setgid), which reduces the area |
| 206 |
of attack immensely. |
| 207 |
.PP |
| 208 |
Libptytty is written in \*(C+, but it also offers a C\-only \s-1API\s0. |
| 209 |
.SH "SECURITY CONSIDERATIONS" |
| 210 |
.IX Header "SECURITY CONSIDERATIONS" |
| 211 |
\&\fI\f(BIIt is of paramount importance that you at least read the following |
| 212 |
paragraph!\fI\fR |
| 213 |
.PP |
| 214 |
If you are a typical terminal-like program that just wants one or more |
| 215 |
ptys, you should call the \f(CW\*(C`ptytty::init ()\*(C'\fR method (C: \f(CW\*(C`ptytty_init ()\*(C'\fR |
| 216 |
function) as the very first thing in your program: |
| 217 |
.PP |
| 218 |
.Vb 5 |
| 219 |
\& int main (int argc, char *argv[]) |
| 220 |
\& { |
| 221 |
\& // do nothing here |
| 222 |
\& ptytty::init (); |
| 223 |
\& // in C: ptytty_init (); |
| 224 |
.Ve |
| 225 |
.PP |
| 226 |
.Vb 2 |
| 227 |
\& // initialise, parse arguments, etc. |
| 228 |
\& } |
| 229 |
.Ve |
| 230 |
.PP |
| 231 |
This checks wether the program runs setuid or setgid. If yes then it will |
| 232 |
fork a helper process and drop privileges. |
| 233 |
.PP |
| 234 |
Some programs need finer control over if and when this helper process |
| 235 |
is started, and if and how to drop privileges. For those programs, the |
| 236 |
methods \f(CW\*(C`ptytty::use_helper\*(C'\fR and \f(CW\*(C`ptytty::drop_privileges\*(C'\fR are more |
| 237 |
useful. |
| 238 |
.SH "\*(C+ INTERFACE: THE ptytty CLASS" |
| 239 |
.IX Header " INTERFACE: THE ptytty CLASS" |
| 240 |
.Sh "\s-1STATIC\s0 \s-1METHODS\s0" |
| 241 |
.IX Subsection "STATIC METHODS" |
| 242 |
.IP "ptytty::init ()" 4 |
| 243 |
.IX Item "ptytty::init ()" |
| 244 |
The default way to initialise libptytty. Must be called imemdiately as |
| 245 |
the first thing in the \f(CW\*(C`main\*(C'\fR function, or earlier e.g. during static |
| 246 |
construction time. The earlier, the better. |
| 247 |
.Sp |
| 248 |
This method checks wether the program runs with setuid/setgid permissions |
| 249 |
and, if yes, spawns a helper process for pty/tty management. It then |
| 250 |
drops the privileges completely, so the actual program runs without |
| 251 |
setuid/setgid privileges. |
| 252 |
.IP "ptytty::use_helper ()" 4 |
| 253 |
.IX Item "ptytty::use_helper ()" |
| 254 |
Tries to start a helper process that retains privileges even when the |
| 255 |
calling process does not. This is usually called from \f(CW\*(C`ptytty::init\*(C'\fR when |
| 256 |
it detects that the program is running setuid or setgid, but can be called |
| 257 |
manually if it is inconvinient to drop privileges at startup, or when |
| 258 |
you are not running setuid/setgid but want to drop privileges (e.g. when |
| 259 |
running as a root-started daemon). |
| 260 |
.Sp |
| 261 |
This method will try not to start more than one helper process. The same |
| 262 |
helper process can usually be used both from the process starting it and |
| 263 |
all its fork'ed (not exec'ed) children. |
| 264 |
.IP "ptytty::drop_privileges ()" 4 |
| 265 |
.IX Item "ptytty::drop_privileges ()" |
| 266 |
Drops privileges completely, i.e. sets real, effective and saved user id |
| 267 |
to the real user id. Also aborts if this cannot be achieved. Useful to |
| 268 |
make sure that the process doesn't run with special privileges. |
| 269 |
.IP "bool success = ptytty::send_fd (int socket, int fd)" 4 |
| 270 |
.IX Item "bool success = ptytty::send_fd (int socket, int fd)" |
| 271 |
Utility method to send a file descriptor over a unix domain |
| 272 |
socket. Returns true if successful, false otherwise. This method is only |
| 273 |
exposed for your convinience and is not required for normal operation. |
| 274 |
.IP "int fd = ptytty::recv_fd (int socket)" 4 |
| 275 |
.IX Item "int fd = ptytty::recv_fd (int socket)" |
| 276 |
Utility method to receive a file descriptor over a unix domain |
| 277 |
socket. Returns the fd if sucecssful and \f(CW\*(C`\-1\*(C'\fR otherwise. This method |
| 278 |
is only exposed for your convinience and is not required for normal |
| 279 |
operation. |
| 280 |
.IP "ptytty *pty = ptytty::create ()" 4 |
| 281 |
.IX Item "ptytty *pty = ptytty::create ()" |
| 282 |
Creates new ptytty object. Creation does not yet do anything besides |
| 283 |
allocating the structure. |
| 284 |
.Sp |
| 285 |
A static method is used because the actual ptytty implementation can |
| 286 |
differ at runtime, so you need a dynamic object creation facility. |
| 287 |
.Sh "\s-1DYNAMIC/SESSION\-RELATED\s0 \s-1DATA\s0 \s-1MEMBERS\s0 \s-1AND\s0 \s-1METHODS\s0" |
| 288 |
.IX Subsection "DYNAMIC/SESSION-RELATED DATA MEMBERS AND METHODS" |
| 289 |
.IP "int pty_fd = pty\->pty" 4 |
| 290 |
.IX Item "int pty_fd = pty->pty" |
| 291 |
.PD 0 |
| 292 |
.IP "int tty_fd = pty\->tty" 4 |
| 293 |
.IX Item "int tty_fd = pty->tty" |
| 294 |
.PD |
| 295 |
These members contain the pty and tty file descriptors, respectively. They |
| 296 |
initially contain \f(CW\*(C`\-1\*(C'\fR until a successful to \f(CW\*(C`ptytty::get\*(C'\fR. |
| 297 |
.IP "bool success = pty\->get ()" 4 |
| 298 |
.IX Item "bool success = pty->get ()" |
| 299 |
Tries to find, allocate and initialise a new pty/tty pair. Returns \f(CW\*(C`true\*(C'\fR |
| 300 |
when successful. |
| 301 |
.IP "pty\->login (int cmd_pid, bool login_shell, const char *hostname)" 4 |
| 302 |
.IX Item "pty->login (int cmd_pid, bool login_shell, const char *hostname)" |
| 303 |
Creates an entry in the systems session database(s) (utmp, wtmp, lastlog). |
| 304 |
\&\f(CW\*(C`cmd_pid\*(C'\fR must be the pid of the process representing the session |
| 305 |
(such as the login shell), \f(CW\*(C`login_shell\*(C'\fR defines wether the session is |
| 306 |
associated with a login, which influences wether wtmp and lastlog entries |
| 307 |
are created, and \f(CW\*(C`hostname\*(C'\fR should identify the \*(L"hostname\*(R" the user logs |
| 308 |
in from, which often is the value of the \f(CW\*(C`DISPLAY\*(C'\fR variable or tty line |
| 309 |
in case of local logins. |
| 310 |
.Sp |
| 311 |
Calling this method is optional. A session starts at the time of the login |
| 312 |
call and extends until the ptytty object is destroyed. |
| 313 |
.IP "pty\->close_tty ()" 4 |
| 314 |
.IX Item "pty->close_tty ()" |
| 315 |
Closes the tty. Useful after forking in the parent/pty process. |
| 316 |
.IP "bool success = pty\->make_controlling_tty ()" 4 |
| 317 |
.IX Item "bool success = pty->make_controlling_tty ()" |
| 318 |
Tries to make the pty/tty pair the controlling terminal of the current |
| 319 |
process. Useful after forking in the child/tty process. |
| 320 |
.IP "pty\->set_utf8_mode (bool on)" 4 |
| 321 |
.IX Item "pty->set_utf8_mode (bool on)" |
| 322 |
On systems supporting special \s-1UTF\-8\s0 line disciplines (e.g. Linux), this |
| 323 |
tries to enable this discipline for the given pty. Can be called at any |
| 324 |
time to change the mode. |
| 325 |
.SH "C INTERFACE: THE ptytty FAMILY OF FUNCTIONS" |
| 326 |
.IX Header "C INTERFACE: THE ptytty FAMILY OF FUNCTIONS" |
| 327 |
.IP "ptytty_init ()" 4 |
| 328 |
.IX Item "ptytty_init ()" |
| 329 |
See \f(CW\*(C`ptytty::init ()\*(C'\fR. |
| 330 |
.IP "\s-1PTYTTY\s0 ptytty_create ()" 4 |
| 331 |
.IX Item "PTYTTY ptytty_create ()" |
| 332 |
Creates a new opaque \s-1PTYTTY\s0 object and returns it. Do not try to access it |
| 333 |
in any way except by testing it for truthness (e.g. \f(CW\*(C`if (pty) ....\*(C'\fR). See |
| 334 |
\&\f(CW\*(C`ptytty::create ()\*(C'\fR. |
| 335 |
.IP "int ptytty_pty (\s-1PTYTTY\s0 ptytty)" 4 |
| 336 |
.IX Item "int ptytty_pty (PTYTTY ptytty)" |
| 337 |
Return the pty file descriptor. See \f(CW\*(C`pty\->pty\*(C'\fR. |
| 338 |
.IP "int ptytty_tty (\s-1PTYTTY\s0 ptytty)" 4 |
| 339 |
.IX Item "int ptytty_tty (PTYTTY ptytty)" |
| 340 |
Return the tty file descriptor. See \f(CW\*(C`pty\->tty\*(C'\fR. |
| 341 |
.IP "void ptytty_delete (\s-1PTYTTY\s0 ptytty)" 4 |
| 342 |
.IX Item "void ptytty_delete (PTYTTY ptytty)" |
| 343 |
Destroys the \s-1PTYTTY\s0 object, freeing the pty/tty pair and cleaning up the |
| 344 |
utmp/wtmp/lastlog databases, if initialised/used. Same as \f(CW\*(C`delete pty\*(C'\fR in |
| 345 |
\&\*(C+. |
| 346 |
.IP "int ptytty_get (\s-1PTYTTY\s0 ptytty)" 4 |
| 347 |
.IX Item "int ptytty_get (PTYTTY ptytty)" |
| 348 |
See \f(CW\*(C`pty\->get\*(C'\fR, returns 0 in case of an error, non-zero otherwise. |
| 349 |
.IP "void ptytty_login (\s-1PTYTTY\s0 ptytty, int cmd_pid, bool login_shell, const char *hostname)" 4 |
| 350 |
.IX Item "void ptytty_login (PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname)" |
| 351 |
See \f(CW\*(C`pty\->login\*(C'\fR. |
| 352 |
.IP "void ptytty_close_tty (\s-1PTYTTY\s0 ptytty)" 4 |
| 353 |
.IX Item "void ptytty_close_tty (PTYTTY ptytty)" |
| 354 |
See \f(CW\*(C`pty\->close_tty\*(C'\fR. |
| 355 |
.IP "int ptytty_make_controlling_tty (\s-1PTYTTY\s0 ptytty)" 4 |
| 356 |
.IX Item "int ptytty_make_controlling_tty (PTYTTY ptytty)" |
| 357 |
See \f(CW\*(C`pty\->make_controlling_tty\*(C'\fR. |
| 358 |
.IP "void ptytty_set_utf8_mode (\s-1PTYTTY\s0 ptytty, int on)" 4 |
| 359 |
.IX Item "void ptytty_set_utf8_mode (PTYTTY ptytty, int on)" |
| 360 |
See \f(CW\*(C`pty\->set_utf8_mode\*(C'\fR. |
| 361 |
.IP "void ptytty_drop_privileges ()" 4 |
| 362 |
.IX Item "void ptytty_drop_privileges ()" |
| 363 |
See \f(CW\*(C`ptytty::drop_privileges\*(C'\fR. |
| 364 |
.IP "void ptytty_use_helper ()" 4 |
| 365 |
.IX Item "void ptytty_use_helper ()" |
| 366 |
See \f(CW\*(C`ptytty::use_helper\*(C'\fR. |
| 367 |
.SH "BUGS" |
| 368 |
.IX Header "BUGS" |
| 369 |
You kiddin'? |
| 370 |
.SH "AUTHORS" |
| 371 |
.IX Header "AUTHORS" |
| 372 |
Emanuele Giaquinta <e.giaquinta@glauco.it>, Marc Alexander Lehmann |
| 373 |
<rxvt\-unicode@schmorp.de>. |
