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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 | RCSID("$OpenBSD: sshpty.c,v 1.11 2004/01/11 21:55:06 deraadt Exp $"); | |
16 | ||
17 | #ifdef HAVE_UTIL_H | |
18 | # include <util.h> | |
19 | #endif /* HAVE_UTIL_H */ | |
20 | ||
21 | #include "sshpty.h" | |
22 | #include "log.h" | |
23 | #include "misc.h" | |
24 | ||
25 | #ifdef HAVE_PTY_H | |
26 | # include <pty.h> | |
27 | #endif | |
28 | ||
29 | #ifndef O_NOCTTY | |
30 | #define O_NOCTTY 0 | |
31 | #endif | |
32 | ||
33 | /* | |
34 | * Allocates and opens a pty. Returns 0 if no pty could be allocated, or | |
35 | * nonzero if a pty was successfully allocated. On success, open file | |
36 | * descriptors for the pty and tty sides and the name of the tty side are | |
37 | * returned (the buffer must be able to hold at least 64 characters). | |
38 | */ | |
39 | ||
40 | int | |
41 | pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen) | |
42 | { | |
43 | /* openpty(3) exists in OSF/1 and some other os'es */ | |
44 | char *name; | |
45 | int i; | |
46 | ||
47 | i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); | |
48 | if (i < 0) { | |
49 | error("openpty: %.100s", strerror(errno)); | |
50 | return 0; | |
51 | } | |
52 | name = ttyname(*ttyfd); | |
53 | if (!name) | |
54 | fatal("openpty returns device for which ttyname fails."); | |
55 | ||
56 | strlcpy(namebuf, name, namebuflen); /* possible truncation */ | |
57 | return 1; | |
58 | } | |
59 | ||
60 | /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ | |
61 | ||
62 | void | |
63 | pty_release(const char *ttyname) | |
64 | { | |
65 | if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0) | |
66 | error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno)); | |
67 | if (chmod(ttyname, (mode_t) 0666) < 0) | |
68 | error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno)); | |
69 | } | |
70 | ||
71 | /* Makes the tty the process's controlling tty and sets it to sane modes. */ | |
72 | ||
73 | void | |
74 | pty_make_controlling_tty(int *ttyfd, const char *ttyname) | |
75 | { | |
76 | int fd; | |
77 | #ifdef USE_VHANGUP | |
78 | void *old; | |
79 | #endif /* USE_VHANGUP */ | |
80 | ||
81 | #ifdef _UNICOS | |
82 | if (setsid() < 0) | |
83 | error("setsid: %.100s", strerror(errno)); | |
84 | ||
85 | fd = open(ttyname, O_RDWR|O_NOCTTY); | |
86 | if (fd != -1) { | |
87 | signal(SIGHUP, SIG_IGN); | |
88 | ioctl(fd, TCVHUP, (char *)NULL); | |
89 | signal(SIGHUP, SIG_DFL); | |
90 | setpgid(0, 0); | |
91 | close(fd); | |
92 | } else { | |
93 | error("Failed to disconnect from controlling tty."); | |
94 | } | |
95 | ||
96 | debug("Setting controlling tty using TCSETCTTY."); | |
97 | ioctl(*ttyfd, TCSETCTTY, NULL); | |
98 | fd = open("/dev/tty", O_RDWR); | |
99 | if (fd < 0) | |
100 | error("%.100s: %.100s", ttyname, strerror(errno)); | |
101 | close(*ttyfd); | |
102 | *ttyfd = fd; | |
103 | #else /* _UNICOS */ | |
104 | ||
105 | /* First disconnect from the old controlling tty. */ | |
106 | #ifdef TIOCNOTTY | |
107 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
108 | if (fd >= 0) { | |
109 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
110 | close(fd); | |
111 | } | |
112 | #endif /* TIOCNOTTY */ | |
113 | if (setsid() < 0) | |
114 | error("setsid: %.100s", strerror(errno)); | |
115 | ||
116 | /* | |
117 | * Verify that we are successfully disconnected from the controlling | |
118 | * tty. | |
119 | */ | |
120 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
121 | if (fd >= 0) { | |
122 | error("Failed to disconnect from controlling tty."); | |
123 | close(fd); | |
124 | } | |
125 | /* Make it our controlling tty. */ | |
126 | #ifdef TIOCSCTTY | |
127 | debug("Setting controlling tty using TIOCSCTTY."); | |
128 | if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) | |
129 | error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); | |
130 | #endif /* TIOCSCTTY */ | |
131 | #ifdef HAVE_NEWS4 | |
132 | if (setpgrp(0,0) < 0) | |
133 | error("SETPGRP %s",strerror(errno)); | |
134 | #endif /* HAVE_NEWS4 */ | |
135 | #ifdef USE_VHANGUP | |
136 | old = signal(SIGHUP, SIG_IGN); | |
137 | vhangup(); | |
138 | signal(SIGHUP, old); | |
139 | #endif /* USE_VHANGUP */ | |
140 | fd = open(ttyname, O_RDWR); | |
141 | if (fd < 0) { | |
142 | error("%.100s: %.100s", ttyname, strerror(errno)); | |
143 | } else { | |
144 | #ifdef USE_VHANGUP | |
145 | close(*ttyfd); | |
146 | *ttyfd = fd; | |
147 | #else /* USE_VHANGUP */ | |
148 | close(fd); | |
149 | #endif /* USE_VHANGUP */ | |
150 | } | |
151 | /* Verify that we now have a controlling tty. */ | |
152 | fd = open(_PATH_TTY, O_WRONLY); | |
153 | if (fd < 0) | |
154 | error("open /dev/tty failed - could not set controlling tty: %.100s", | |
155 | strerror(errno)); | |
156 | else | |
157 | close(fd); | |
158 | #endif /* _UNICOS */ | |
159 | } | |
160 | ||
161 | /* Changes the window size associated with the pty. */ | |
162 | ||
163 | void | |
164 | pty_change_window_size(int ptyfd, int row, int col, | |
165 | int xpixel, int ypixel) | |
166 | { | |
167 | struct winsize w; | |
168 | ||
169 | w.ws_row = row; | |
170 | w.ws_col = col; | |
171 | w.ws_xpixel = xpixel; | |
172 | w.ws_ypixel = ypixel; | |
173 | (void) ioctl(ptyfd, TIOCSWINSZ, &w); | |
174 | } | |
175 | ||
176 | void | |
177 | pty_setowner(struct passwd *pw, const char *ttyname) | |
178 | { | |
179 | struct group *grp; | |
180 | gid_t gid; | |
181 | mode_t mode; | |
182 | struct stat st; | |
183 | ||
184 | /* Determine the group to make the owner of the tty. */ | |
185 | grp = getgrnam("tty"); | |
186 | if (grp) { | |
187 | gid = grp->gr_gid; | |
188 | mode = S_IRUSR | S_IWUSR | S_IWGRP; | |
189 | } else { | |
190 | gid = pw->pw_gid; | |
191 | mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; | |
192 | } | |
193 | ||
194 | /* | |
195 | * Change owner and mode of the tty as required. | |
196 | * Warn but continue if filesystem is read-only and the uids match/ | |
197 | * tty is owned by root. | |
198 | */ | |
199 | if (stat(ttyname, &st)) | |
200 | fatal("stat(%.100s) failed: %.100s", ttyname, | |
201 | strerror(errno)); | |
202 | ||
203 | if (st.st_uid != pw->pw_uid || st.st_gid != gid) { | |
204 | if (chown(ttyname, pw->pw_uid, gid) < 0) { | |
205 | if (errno == EROFS && | |
206 | (st.st_uid == pw->pw_uid || st.st_uid == 0)) | |
207 | debug("chown(%.100s, %u, %u) failed: %.100s", | |
208 | ttyname, (u_int)pw->pw_uid, (u_int)gid, | |
209 | strerror(errno)); | |
210 | else | |
211 | fatal("chown(%.100s, %u, %u) failed: %.100s", | |
212 | ttyname, (u_int)pw->pw_uid, (u_int)gid, | |
213 | strerror(errno)); | |
214 | } | |
215 | } | |
216 | ||
217 | if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { | |
218 | if (chmod(ttyname, mode) < 0) { | |
219 | if (errno == EROFS && | |
220 | (st.st_mode & (S_IRGRP | S_IROTH)) == 0) | |
221 | debug("chmod(%.100s, 0%o) failed: %.100s", | |
222 | ttyname, (u_int)mode, strerror(errno)); | |
223 | else | |
224 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
225 | ttyname, (u_int)mode, strerror(errno)); | |
226 | } | |
227 | } | |
228 | } |