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47686178 | 1 | /* $OpenBSD: sshpty.c,v 1.28 2007/09/11 23:49:09 stevesk Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * Allocating a pseudo-terminal, and making it the controlling tty. | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
3c0ef626 | 16 | |
9108f8d9 | 17 | #include <sys/types.h> |
18 | #include <sys/ioctl.h> | |
19 | #include <sys/stat.h> | |
20 | #include <signal.h> | |
21 | ||
22 | #include <errno.h> | |
23 | #include <fcntl.h> | |
24 | #include <grp.h> | |
25 | #ifdef HAVE_PATHS_H | |
26 | # include <paths.h> | |
27 | #endif | |
28 | #include <pwd.h> | |
29 | #include <stdarg.h> | |
30 | #include <string.h> | |
31 | #include <termios.h> | |
3c0ef626 | 32 | #ifdef HAVE_UTIL_H |
33 | # include <util.h> | |
9108f8d9 | 34 | #endif |
35 | #include <unistd.h> | |
3c0ef626 | 36 | |
37 | #include "sshpty.h" | |
38 | #include "log.h" | |
39 | #include "misc.h" | |
40 | ||
3c0ef626 | 41 | #ifdef HAVE_PTY_H |
42 | # include <pty.h> | |
43 | #endif | |
3c0ef626 | 44 | |
45 | #ifndef O_NOCTTY | |
46 | #define O_NOCTTY 0 | |
47 | #endif | |
48 | ||
91d9cdd3 | 49 | #ifdef __APPLE__ |
50 | # include <AvailabilityMacros.h> | |
51 | # if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5) | |
52 | # define __APPLE_PRIVPTY__ | |
53 | # endif | |
54 | #endif | |
55 | ||
3c0ef626 | 56 | /* |
57 | * Allocates and opens a pty. Returns 0 if no pty could be allocated, or | |
58 | * nonzero if a pty was successfully allocated. On success, open file | |
59 | * descriptors for the pty and tty sides and the name of the tty side are | |
60 | * returned (the buffer must be able to hold at least 64 characters). | |
61 | */ | |
62 | ||
63 | int | |
9108f8d9 | 64 | pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen) |
3c0ef626 | 65 | { |
3c0ef626 | 66 | /* openpty(3) exists in OSF/1 and some other os'es */ |
67 | char *name; | |
68 | int i; | |
69 | ||
70 | i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); | |
71 | if (i < 0) { | |
72 | error("openpty: %.100s", strerror(errno)); | |
73 | return 0; | |
74 | } | |
75 | name = ttyname(*ttyfd); | |
76 | if (!name) | |
77 | fatal("openpty returns device for which ttyname fails."); | |
78 | ||
79 | strlcpy(namebuf, name, namebuflen); /* possible truncation */ | |
80 | return 1; | |
3c0ef626 | 81 | } |
82 | ||
83 | /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ | |
84 | ||
85 | void | |
c9f39d2c | 86 | pty_release(const char *tty) |
3c0ef626 | 87 | { |
91d9cdd3 | 88 | #ifndef __APPLE_PRIVPTY__ |
c9f39d2c | 89 | if (chown(tty, (uid_t) 0, (gid_t) 0) < 0) |
90 | error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); | |
91 | if (chmod(tty, (mode_t) 0666) < 0) | |
92 | error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno)); | |
91d9cdd3 | 93 | #endif /* __APPLE_PRIVPTY__ */ |
3c0ef626 | 94 | } |
95 | ||
0fff78ff | 96 | /* Makes the tty the process's controlling tty and sets it to sane modes. */ |
3c0ef626 | 97 | |
98 | void | |
c9f39d2c | 99 | pty_make_controlling_tty(int *ttyfd, const char *tty) |
3c0ef626 | 100 | { |
101 | int fd; | |
102 | #ifdef USE_VHANGUP | |
103 | void *old; | |
104 | #endif /* USE_VHANGUP */ | |
105 | ||
41b2f314 | 106 | #ifdef _UNICOS |
3c0ef626 | 107 | if (setsid() < 0) |
108 | error("setsid: %.100s", strerror(errno)); | |
109 | ||
c9f39d2c | 110 | fd = open(tty, O_RDWR|O_NOCTTY); |
3c0ef626 | 111 | if (fd != -1) { |
0fff78ff | 112 | signal(SIGHUP, SIG_IGN); |
3c0ef626 | 113 | ioctl(fd, TCVHUP, (char *)NULL); |
0fff78ff | 114 | signal(SIGHUP, SIG_DFL); |
3c0ef626 | 115 | setpgid(0, 0); |
116 | close(fd); | |
117 | } else { | |
118 | error("Failed to disconnect from controlling tty."); | |
119 | } | |
120 | ||
121 | debug("Setting controlling tty using TCSETCTTY."); | |
122 | ioctl(*ttyfd, TCSETCTTY, NULL); | |
123 | fd = open("/dev/tty", O_RDWR); | |
124 | if (fd < 0) | |
c9f39d2c | 125 | error("%.100s: %.100s", tty, strerror(errno)); |
3c0ef626 | 126 | close(*ttyfd); |
f5799ae1 | 127 | *ttyfd = fd; |
41b2f314 | 128 | #else /* _UNICOS */ |
3c0ef626 | 129 | |
130 | /* First disconnect from the old controlling tty. */ | |
131 | #ifdef TIOCNOTTY | |
132 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
133 | if (fd >= 0) { | |
134 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
135 | close(fd); | |
136 | } | |
137 | #endif /* TIOCNOTTY */ | |
138 | if (setsid() < 0) | |
139 | error("setsid: %.100s", strerror(errno)); | |
140 | ||
141 | /* | |
142 | * Verify that we are successfully disconnected from the controlling | |
143 | * tty. | |
144 | */ | |
145 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
146 | if (fd >= 0) { | |
147 | error("Failed to disconnect from controlling tty."); | |
148 | close(fd); | |
149 | } | |
150 | /* Make it our controlling tty. */ | |
151 | #ifdef TIOCSCTTY | |
152 | debug("Setting controlling tty using TIOCSCTTY."); | |
153 | if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) | |
154 | error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); | |
155 | #endif /* TIOCSCTTY */ | |
665a873d | 156 | #ifdef NEED_SETPGRP |
3c0ef626 | 157 | if (setpgrp(0,0) < 0) |
158 | error("SETPGRP %s",strerror(errno)); | |
665a873d | 159 | #endif /* NEED_SETPGRP */ |
3c0ef626 | 160 | #ifdef USE_VHANGUP |
0fff78ff | 161 | old = signal(SIGHUP, SIG_IGN); |
3c0ef626 | 162 | vhangup(); |
0fff78ff | 163 | signal(SIGHUP, old); |
3c0ef626 | 164 | #endif /* USE_VHANGUP */ |
c9f39d2c | 165 | fd = open(tty, O_RDWR); |
3c0ef626 | 166 | if (fd < 0) { |
c9f39d2c | 167 | error("%.100s: %.100s", tty, strerror(errno)); |
3c0ef626 | 168 | } else { |
169 | #ifdef USE_VHANGUP | |
170 | close(*ttyfd); | |
171 | *ttyfd = fd; | |
172 | #else /* USE_VHANGUP */ | |
173 | close(fd); | |
174 | #endif /* USE_VHANGUP */ | |
175 | } | |
176 | /* Verify that we now have a controlling tty. */ | |
177 | fd = open(_PATH_TTY, O_WRONLY); | |
178 | if (fd < 0) | |
179 | error("open /dev/tty failed - could not set controlling tty: %.100s", | |
e9a17296 | 180 | strerror(errno)); |
cdd66111 | 181 | else |
3c0ef626 | 182 | close(fd); |
41b2f314 | 183 | #endif /* _UNICOS */ |
3c0ef626 | 184 | } |
185 | ||
186 | /* Changes the window size associated with the pty. */ | |
187 | ||
188 | void | |
9108f8d9 | 189 | pty_change_window_size(int ptyfd, u_int row, u_int col, |
190 | u_int xpixel, u_int ypixel) | |
3c0ef626 | 191 | { |
192 | struct winsize w; | |
680cee3b | 193 | |
9108f8d9 | 194 | /* may truncate u_int -> u_short */ |
3c0ef626 | 195 | w.ws_row = row; |
196 | w.ws_col = col; | |
197 | w.ws_xpixel = xpixel; | |
198 | w.ws_ypixel = ypixel; | |
199 | (void) ioctl(ptyfd, TIOCSWINSZ, &w); | |
200 | } | |
201 | ||
202 | void | |
c9f39d2c | 203 | pty_setowner(struct passwd *pw, const char *tty) |
3c0ef626 | 204 | { |
205 | struct group *grp; | |
206 | gid_t gid; | |
207 | mode_t mode; | |
208 | struct stat st; | |
209 | ||
210 | /* Determine the group to make the owner of the tty. */ | |
211 | grp = getgrnam("tty"); | |
212 | if (grp) { | |
213 | gid = grp->gr_gid; | |
214 | mode = S_IRUSR | S_IWUSR | S_IWGRP; | |
215 | } else { | |
216 | gid = pw->pw_gid; | |
217 | mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; | |
218 | } | |
219 | ||
220 | /* | |
221 | * Change owner and mode of the tty as required. | |
222 | * Warn but continue if filesystem is read-only and the uids match/ | |
223 | * tty is owned by root. | |
224 | */ | |
c9f39d2c | 225 | if (stat(tty, &st)) |
226 | fatal("stat(%.100s) failed: %.100s", tty, | |
3c0ef626 | 227 | strerror(errno)); |
228 | ||
9108f8d9 | 229 | #ifdef WITH_SELINUX |
230 | ssh_selinux_setup_pty(pw->pw_name, tty); | |
231 | #endif | |
232 | ||
3c0ef626 | 233 | if (st.st_uid != pw->pw_uid || st.st_gid != gid) { |
c9f39d2c | 234 | if (chown(tty, pw->pw_uid, gid) < 0) { |
e9a17296 | 235 | if (errno == EROFS && |
680cee3b | 236 | (st.st_uid == pw->pw_uid || st.st_uid == 0)) |
6a9b3198 | 237 | debug("chown(%.100s, %u, %u) failed: %.100s", |
c9f39d2c | 238 | tty, (u_int)pw->pw_uid, (u_int)gid, |
e9a17296 | 239 | strerror(errno)); |
3c0ef626 | 240 | else |
680cee3b | 241 | fatal("chown(%.100s, %u, %u) failed: %.100s", |
c9f39d2c | 242 | tty, (u_int)pw->pw_uid, (u_int)gid, |
e9a17296 | 243 | strerror(errno)); |
3c0ef626 | 244 | } |
245 | } | |
246 | ||
247 | if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { | |
c9f39d2c | 248 | if (chmod(tty, mode) < 0) { |
3c0ef626 | 249 | if (errno == EROFS && |
250 | (st.st_mode & (S_IRGRP | S_IROTH)) == 0) | |
6a9b3198 | 251 | debug("chmod(%.100s, 0%o) failed: %.100s", |
c9f39d2c | 252 | tty, (u_int)mode, strerror(errno)); |
3c0ef626 | 253 | else |
254 | fatal("chmod(%.100s, 0%o) failed: %.100s", | |
c9f39d2c | 255 | tty, (u_int)mode, strerror(errno)); |
3c0ef626 | 256 | } |
257 | } | |
258 | } |