1 /*
2 * Please note: this implementation of openpty() is far from complete.
3 * it is just enough for portable OpenSSH's needs.
4 */
5
6 /*
7 * Copyright (c) 2004 Damien Miller <djm@mindrot.org>
8 *
9 * Permission to use, copy, modify, and distribute this software for any
10 * purpose with or without fee is hereby granted, provided that the above
11 * copyright notice and this permission notice appear in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
14 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
16 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
19 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 */
21
22 /*
23 * Author: Tatu Ylonen <ylo@cs.hut.fi>
24 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
25 * All rights reserved
26 * Allocating a pseudo-terminal, and making it the controlling tty.
27 *
28 * As far as I am concerned, the code I have written for this software
29 * can be used freely for any purpose. Any derived versions of this
30 * software must be clearly marked as such, and if the derived work is
31 * incompatible with the protocol description in the RFC file, it must be
32 * called by a name other than "ssh" or "Secure Shell".
33 */
34
35 #include "includes.h"
36 #if !defined(HAVE_OPENPTY)
37
38 #include <sys/types.h>
39
40 #include <stdlib.h>
41
42 #ifdef HAVE_SYS_STAT_H
43 # include <sys/stat.h>
44 #endif
45 #ifdef HAVE_SYS_IOCTL_H
46 # include <sys/ioctl.h>
47 #endif
48
49 #ifdef HAVE_FCNTL_H
50 # include <fcntl.h>
51 #endif
52
53 #ifdef HAVE_UTIL_H
54 # include <util.h>
55 #endif /* HAVE_UTIL_H */
56
57 #ifdef HAVE_PTY_H
58 # include <pty.h>
59 #endif
60 #if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
61 # include <sys/stropts.h>
62 #endif
63
64 #include <signal.h>
65 #include <string.h>
66 #include <unistd.h>
67
68 #include "misc.h"
69 #include "log.h"
70
71 #ifndef O_NOCTTY
72 #define O_NOCTTY 0
73 #endif
74
75 #if defined(HAVE_DEV_PTMX) && !defined(HAVE__GETPTY)
76 static int
openpty_streams(int * amaster,int * aslave)77 openpty_streams(int *amaster, int *aslave)
78 {
79 /*
80 * This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3
81 * also has bsd-style ptys, but they simply do not work.)
82 */
83 int ptm;
84 char *pts;
85 sshsig_t old_signal;
86
87 if ((ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY)) == -1)
88 return (-1);
89
90 /* XXX: need to close ptm on error? */
91 old_signal = ssh_signal(SIGCHLD, SIG_DFL);
92 if (grantpt(ptm) < 0)
93 return (-1);
94 ssh_signal(SIGCHLD, old_signal);
95
96 if (unlockpt(ptm) < 0)
97 return (-1);
98
99 if ((pts = ptsname(ptm)) == NULL)
100 return (-1);
101 *amaster = ptm;
102
103 /* Open the slave side. */
104 if ((*aslave = open(pts, O_RDWR | O_NOCTTY)) == -1) {
105 close(*amaster);
106 return (-1);
107 }
108
109 # if defined(I_FIND) && defined(__SVR4)
110 /*
111 * If the streams modules have already been pushed then there
112 * is no more work to do here.
113 */
114 if (ioctl(*aslave, I_FIND, "ptem") != 0)
115 return 0;
116 # endif
117
118 /*
119 * Try to push the appropriate streams modules, as described
120 * in Solaris pts(7).
121 */
122 ioctl(*aslave, I_PUSH, "ptem");
123 ioctl(*aslave, I_PUSH, "ldterm");
124 # ifndef __hpux
125 ioctl(*aslave, I_PUSH, "ttcompat");
126 # endif /* __hpux */
127 return (0);
128 }
129 #endif
130
131 int
openpty(int * amaster,int * aslave,char * name,struct termios * termp,struct winsize * winp)132 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
133 struct winsize *winp)
134 {
135 #if defined(HAVE__GETPTY)
136 /*
137 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
138 * pty's automagically when needed
139 */
140 char *slave;
141
142 if ((slave = _getpty(amaster, O_RDWR, 0622, 0)) == NULL)
143 return (-1);
144
145 /* Open the slave side. */
146 if ((*aslave = open(slave, O_RDWR | O_NOCTTY)) == -1) {
147 close(*amaster);
148 return (-1);
149 }
150 return (0);
151
152 #elif defined(HAVE_DEV_PTMX)
153
154 #ifdef SSHD_ACQUIRES_CTTY
155 /*
156 * On some (most? all?) SysV based systems with STREAMS based terminals,
157 * sshd will acquire a controlling terminal when it pushes the "ptem"
158 * module. On such platforms, first allocate a sacrificial pty so
159 * that sshd already has a controlling terminal before allocating the
160 * one that will be passed back to the user process. This ensures
161 * the second pty is not already the controlling terminal for a
162 * different session and is available to become controlling terminal
163 * for the client's subprocess. See bugzilla #245 for details.
164 */
165 int r, fd;
166 static int junk_ptyfd = -1, junk_ttyfd;
167
168 r = openpty_streams(amaster, aslave);
169 if (junk_ptyfd == -1 && (fd = open(_PATH_TTY, O_RDWR|O_NOCTTY)) >= 0) {
170 close(fd);
171 junk_ptyfd = *amaster;
172 junk_ttyfd = *aslave;
173 debug("STREAMS bug workaround pty %d tty %d name %s",
174 junk_ptyfd, junk_ttyfd, ttyname(junk_ttyfd));
175 } else
176 return r;
177 #endif
178
179 return openpty_streams(amaster, aslave);
180
181 #elif defined(HAVE_DEV_PTS_AND_PTC)
182 /* AIX-style pty code. */
183 const char *ttname;
184
185 if ((*amaster = open("/dev/ptc", O_RDWR | O_NOCTTY)) == -1)
186 return (-1);
187 if ((ttname = ttyname(*amaster)) == NULL)
188 return (-1);
189 if ((*aslave = open(ttname, O_RDWR | O_NOCTTY)) == -1) {
190 close(*amaster);
191 return (-1);
192 }
193 return (0);
194
195 #else
196 /* BSD-style pty code. */
197 char ptbuf[64], ttbuf[64];
198 int i;
199 const char *ptymajors = "pqrstuvwxyzabcdefghijklmno"
200 "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
201 const char *ptyminors = "0123456789abcdef";
202 int num_minors = strlen(ptyminors);
203 int num_ptys = strlen(ptymajors) * num_minors;
204 struct termios tio;
205
206 for (i = 0; i < num_ptys; i++) {
207 snprintf(ptbuf, sizeof(ptbuf), "/dev/pty%c%c",
208 ptymajors[i / num_minors], ptyminors[i % num_minors]);
209 snprintf(ttbuf, sizeof(ttbuf), "/dev/tty%c%c",
210 ptymajors[i / num_minors], ptyminors[i % num_minors]);
211
212 if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1) {
213 /* Try SCO style naming */
214 snprintf(ptbuf, sizeof(ptbuf), "/dev/ptyp%d", i);
215 snprintf(ttbuf, sizeof(ttbuf), "/dev/ttyp%d", i);
216 if ((*amaster = open(ptbuf, O_RDWR | O_NOCTTY)) == -1)
217 continue;
218 }
219
220 /* Open the slave side. */
221 if ((*aslave = open(ttbuf, O_RDWR | O_NOCTTY)) == -1) {
222 close(*amaster);
223 return (-1);
224 }
225 /* set tty modes to a sane state for broken clients */
226 if (tcgetattr(*amaster, &tio) != -1) {
227 tio.c_lflag |= (ECHO | ISIG | ICANON);
228 tio.c_oflag |= (OPOST | ONLCR);
229 tio.c_iflag |= ICRNL;
230 tcsetattr(*amaster, TCSANOW, &tio);
231 }
232
233 return (0);
234 }
235 return (-1);
236 #endif
237 }
238
239 #endif /* !defined(HAVE_OPENPTY) */
240
241