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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Allocating a pseudo-terminal, and making it the controlling tty. | |
6 | * | |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
12 | */ | |
13 | ||
14 | #include "includes.h" | |
15 | ||
16 | #include <sys/ioctl.h> | |
17 | #include <sys/types.h> | |
18 | #include <sys/stat.h> | |
19 | #include <signal.h> | |
20 | ||
21 | #ifdef HAVE_PATHS_H | |
22 | # include <paths.h> | |
23 | #endif | |
24 | #include <termios.h> | |
25 | #ifdef HAVE_UTIL_H | |
26 | # include <util.h> | |
27 | #endif /* HAVE_UTIL_H */ | |
28 | ||
29 | #include "sshpty.h" | |
30 | #include "log.h" | |
31 | #include "misc.h" | |
32 | ||
33 | #ifdef HAVE_PTY_H | |
34 | # include <pty.h> | |
35 | #endif | |
36 | ||
37 | #ifndef O_NOCTTY | |
38 | #define O_NOCTTY 0 | |
39 | #endif | |
40 | ||
41 | /* | |
42 | * Allocates and opens a pty. Returns 0 if no pty could be allocated, or | |
43 | * nonzero if a pty was successfully allocated. On success, open file | |
44 | * descriptors for the pty and tty sides and the name of the tty side are | |
45 | * returned (the buffer must be able to hold at least 64 characters). | |
46 | */ | |
47 | ||
48 | int | |
49 | pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen) | |
50 | { | |
51 | /* openpty(3) exists in OSF/1 and some other os'es */ | |
52 | char *name; | |
53 | int i; | |
54 | ||
55 | i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); | |
56 | if (i < 0) { | |
57 | error("openpty: %.100s", strerror(errno)); | |
58 | return 0; | |
59 | } | |
60 | name = ttyname(*ttyfd); | |
61 | if (!name) | |
62 | fatal("openpty returns device for which ttyname fails."); | |
63 | ||
64 | strlcpy(namebuf, name, namebuflen); /* possible truncation */ | |
65 | return 1; | |
66 | } | |
67 | ||
68 | /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ | |
69 | ||
70 | void | |
71 | pty_release(const char *tty) | |
72 | { | |
73 | if (chown(tty, (uid_t) 0, (gid_t) 0) < 0) | |
74 | error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); | |
75 | if (chmod(tty, (mode_t) 0666) < 0) | |
76 | error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno)); | |
77 | } | |
78 | ||
79 | /* Makes the tty the process's controlling tty and sets it to sane modes. */ | |
80 | ||
81 | void | |
82 | pty_make_controlling_tty(int *ttyfd, const char *tty) | |
83 | { | |
84 | int fd; | |
85 | #ifdef USE_VHANGUP | |
86 | void *old; | |
87 | #endif /* USE_VHANGUP */ | |
88 | ||
89 | #ifdef _UNICOS | |
90 | if (setsid() < 0) | |
91 | error("setsid: %.100s", strerror(errno)); | |
92 | ||
93 | fd = open(tty, O_RDWR|O_NOCTTY); | |
94 | if (fd != -1) { | |
95 | signal(SIGHUP, SIG_IGN); | |
96 | ioctl(fd, TCVHUP, (char *)NULL); | |
97 | signal(SIGHUP, SIG_DFL); | |
98 | setpgid(0, 0); | |
99 | close(fd); | |
100 | } else { | |
101 | error("Failed to disconnect from controlling tty."); | |
102 | } | |
103 | ||
104 | debug("Setting controlling tty using TCSETCTTY."); | |
105 | ioctl(*ttyfd, TCSETCTTY, NULL); | |
106 | fd = open("/dev/tty", O_RDWR); | |
107 | if (fd < 0) | |
108 | error("%.100s: %.100s", tty, strerror(errno)); | |
109 | close(*ttyfd); | |
110 | *ttyfd = fd; | |
111 | #else /* _UNICOS */ | |
112 | ||
113 | /* First disconnect from the old controlling tty. */ | |
114 | #ifdef TIOCNOTTY | |
115 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
116 | if (fd >= 0) { | |
117 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
118 | close(fd); | |
119 | } | |
120 | #endif /* TIOCNOTTY */ | |
121 | if (setsid() < 0) | |
122 | error("setsid: %.100s", strerror(errno)); | |
123 | ||
124 | /* | |
125 | * Verify that we are successfully disconnected from the controlling | |
126 | * tty. | |
127 | */ | |
128 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
129 | if (fd >= 0) { | |
130 | error("Failed to disconnect from controlling tty."); | |
131 | close(fd); | |
132 | } | |
133 | /* Make it our controlling tty. */ | |
134 | #ifdef TIOCSCTTY | |
135 | debug("Setting controlling tty using TIOCSCTTY."); | |
136 | if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) | |
137 | error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); | |
138 | #endif /* TIOCSCTTY */ | |
139 | #ifdef NEED_SETPGRP | |
140 | if (setpgrp(0,0) < 0) | |
141 | error("SETPGRP %s",strerror(errno)); | |
142 | #endif /* NEED_SETPGRP */ | |
143 | #ifdef USE_VHANGUP | |
144 | old = signal(SIGHUP, SIG_IGN); | |
145 | vhangup(); | |
146 | signal(SIGHUP, old); | |
147 | #endif /* USE_VHANGUP */ | |
148 | fd = open(tty, O_RDWR); | |
149 | if (fd < 0) { | |
150 | error("%.100s: %.100s", tty, strerror(errno)); | |
151 | } else { | |
152 | #ifdef USE_VHANGUP | |
153 | close(*ttyfd); | |
154 | *ttyfd = fd; | |
155 | #else /* USE_VHANGUP */ | |
156 | close(fd); | |
157 | #endif /* USE_VHANGUP */ | |
158 | } | |
159 | /* Verify that we now have a controlling tty. */ | |
160 | fd = open(_PATH_TTY, O_WRONLY); | |
161 | if (fd < 0) | |
162 | error("open /dev/tty failed - could not set controlling tty: %.100s", | |
163 | strerror(errno)); | |
164 | else | |
165 | close(fd); | |
166 | #endif /* _UNICOS */ | |
167 | } | |
168 | ||
169 | /* Changes the window size associated with the pty. */ | |
170 | ||
171 | void | |
172 | pty_change_window_size(int ptyfd, int row, int col, | |
173 | int xpixel, int ypixel) | |
174 | { | |
175 | struct winsize w; | |
176 | ||
177 | w.ws_row = row; | |
178 | w.ws_col = col; | |
179 | w.ws_xpixel = xpixel; | |
180 | w.ws_ypixel = ypixel; | |
181 | (void) ioctl(ptyfd, TIOCSWINSZ, &w); | |
182 | } | |
183 | ||
184 | void | |
185 | pty_setowner(struct passwd *pw, const char *tty) | |
186 | { | |
187 | struct group *grp; | |
188 | gid_t gid; | |
189 | mode_t mode; | |
190 | struct stat st; | |
191 | ||
192 | /* Determine the group to make the owner of the tty. */ | |
193 | grp = getgrnam("tty"); | |
194 | if (grp) { | |
195 | gid = grp->gr_gid; | |
196 | mode = S_IRUSR | S_IWUSR | S_IWGRP; | |
197 | } else { | |
198 | gid = pw->pw_gid; | |
199 | mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; | |
200 | } | |
201 | ||
202 | /* | |
203 | * Change owner and mode of the tty as required. | |
204 | * Warn but continue if filesystem is read-only and the uids match/ | |
205 | * tty is owned by root. | |
206 | */ | |
207 | if (stat(tty, &st)) | |
208 | fatal("stat(%.100s) failed: %.100s", tty, | |
209 | strerror(errno)); | |
210 | ||
211 | if (st.st_uid != pw->pw_uid || st.st_gid != gid) { | |
212 | if (chown(tty, pw->pw_uid, gid) < 0) { | |
213 | if (errno == EROFS && | |
214 | (st.st_uid == pw->pw_uid || st.st_uid == 0)) | |
215 | debug("chown(%.100s, %u, %u) failed: %.100s", | |
216 | tty, (u_int)pw->pw_uid, (u_int)gid, | |
217 | strerror(errno)); | |
218 | else | |
219 | fatal("chown(%.100s, %u, %u) failed: %.100s", | |
220 | tty, (u_int)pw->pw_uid, (u_int)gid, | |
221 | strerror(errno)); | |
222 | } | |
223 | } | |
224 | ||
225 | if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { | |
226 | if (chmod(tty, mode) < 0) { | |
227 | if (errno == EROFS && | |
228 | (st.st_mode & (S_IRGRP | S_IROTH)) == 0) | |
229 | debug("chmod(%.100s, 0%o) failed: %.100s", | |
230 | tty, (u_int)mode, strerror(errno)); | |
231 | else | |
232 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
233 | tty, (u_int)mode, strerror(errno)); | |
234 | } | |
235 | } | |
236 | } |