Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 1 | /* $OpenBSD: sshpty.c,v 1.29 2014/09/03 18:55:07 djm Exp $ */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 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" |
| 16 | |
| 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> |
| 32 | #ifdef HAVE_UTIL_H |
| 33 | # include <util.h> |
| 34 | #endif |
| 35 | #include <unistd.h> |
| 36 | |
| 37 | #include "sshpty.h" |
| 38 | #include "log.h" |
| 39 | #include "misc.h" |
| 40 | |
| 41 | #ifdef HAVE_PTY_H |
| 42 | # include <pty.h> |
| 43 | #endif |
| 44 | |
| 45 | #ifndef O_NOCTTY |
| 46 | #define O_NOCTTY 0 |
| 47 | #endif |
| 48 | |
| 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 | |
| 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 |
| 64 | pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen) |
| 65 | { |
| 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 | #ifdef ANDROID |
| 76 | /* Android does not have a working ttyname() */ |
| 77 | name = "/dev/ptmx"; |
| 78 | #else |
| 79 | name = ttyname(*ttyfd); |
| 80 | if (!name) |
| 81 | fatal("openpty returns device for which ttyname fails."); |
| 82 | #endif |
| 83 | |
| 84 | strlcpy(namebuf, name, namebuflen); /* possible truncation */ |
| 85 | return 1; |
| 86 | } |
| 87 | |
| 88 | /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ |
| 89 | |
| 90 | void |
| 91 | pty_release(const char *tty) |
| 92 | { |
| 93 | #ifndef __APPLE_PRIVPTY__ |
| 94 | if (chown(tty, (uid_t) 0, (gid_t) 0) < 0) |
| 95 | error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); |
| 96 | if (chmod(tty, (mode_t) 0666) < 0) |
| 97 | error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno)); |
| 98 | #endif /* __APPLE_PRIVPTY__ */ |
| 99 | } |
| 100 | |
| 101 | /* Makes the tty the process's controlling tty and sets it to sane modes. */ |
| 102 | |
| 103 | void |
| 104 | pty_make_controlling_tty(int *ttyfd, const char *tty) |
| 105 | { |
| 106 | int fd; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 107 | |
| 108 | #ifdef _UNICOS |
| 109 | if (setsid() < 0) |
| 110 | error("setsid: %.100s", strerror(errno)); |
| 111 | |
| 112 | fd = open(tty, O_RDWR|O_NOCTTY); |
| 113 | if (fd != -1) { |
| 114 | signal(SIGHUP, SIG_IGN); |
| 115 | ioctl(fd, TCVHUP, (char *)NULL); |
| 116 | signal(SIGHUP, SIG_DFL); |
| 117 | setpgid(0, 0); |
| 118 | close(fd); |
| 119 | } else { |
| 120 | error("Failed to disconnect from controlling tty."); |
| 121 | } |
| 122 | |
| 123 | debug("Setting controlling tty using TCSETCTTY."); |
| 124 | ioctl(*ttyfd, TCSETCTTY, NULL); |
| 125 | fd = open("/dev/tty", O_RDWR); |
| 126 | if (fd < 0) |
| 127 | error("%.100s: %.100s", tty, strerror(errno)); |
| 128 | close(*ttyfd); |
| 129 | *ttyfd = fd; |
| 130 | #else /* _UNICOS */ |
| 131 | |
| 132 | /* First disconnect from the old controlling tty. */ |
| 133 | #ifdef TIOCNOTTY |
| 134 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
| 135 | if (fd >= 0) { |
| 136 | (void) ioctl(fd, TIOCNOTTY, NULL); |
| 137 | close(fd); |
| 138 | } |
| 139 | #endif /* TIOCNOTTY */ |
| 140 | if (setsid() < 0) |
| 141 | error("setsid: %.100s", strerror(errno)); |
| 142 | |
| 143 | /* |
| 144 | * Verify that we are successfully disconnected from the controlling |
| 145 | * tty. |
| 146 | */ |
| 147 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
| 148 | if (fd >= 0) { |
| 149 | error("Failed to disconnect from controlling tty."); |
| 150 | close(fd); |
| 151 | } |
| 152 | /* Make it our controlling tty. */ |
| 153 | #ifdef TIOCSCTTY |
| 154 | debug("Setting controlling tty using TIOCSCTTY."); |
| 155 | if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) |
| 156 | error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); |
| 157 | #endif /* TIOCSCTTY */ |
| 158 | #ifdef NEED_SETPGRP |
| 159 | if (setpgrp(0,0) < 0) |
| 160 | error("SETPGRP %s",strerror(errno)); |
| 161 | #endif /* NEED_SETPGRP */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 162 | fd = open(tty, O_RDWR); |
| 163 | if (fd < 0) { |
| 164 | error("%.100s: %.100s", tty, strerror(errno)); |
| 165 | } else { |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 166 | close(fd); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 167 | } |
| 168 | /* Verify that we now have a controlling tty. */ |
| 169 | fd = open(_PATH_TTY, O_WRONLY); |
| 170 | if (fd < 0) |
| 171 | error("open /dev/tty failed - could not set controlling tty: %.100s", |
| 172 | strerror(errno)); |
| 173 | else |
| 174 | close(fd); |
| 175 | #endif /* _UNICOS */ |
| 176 | } |
| 177 | |
| 178 | /* Changes the window size associated with the pty. */ |
| 179 | |
| 180 | void |
| 181 | pty_change_window_size(int ptyfd, u_int row, u_int col, |
| 182 | u_int xpixel, u_int ypixel) |
| 183 | { |
| 184 | struct winsize w; |
| 185 | |
| 186 | /* may truncate u_int -> u_short */ |
| 187 | w.ws_row = row; |
| 188 | w.ws_col = col; |
| 189 | w.ws_xpixel = xpixel; |
| 190 | w.ws_ypixel = ypixel; |
| 191 | (void) ioctl(ptyfd, TIOCSWINSZ, &w); |
| 192 | } |
| 193 | |
| 194 | void |
| 195 | pty_setowner(struct passwd *pw, const char *tty) |
| 196 | { |
| 197 | struct group *grp; |
| 198 | gid_t gid; |
| 199 | mode_t mode; |
| 200 | struct stat st; |
| 201 | |
| 202 | /* Determine the group to make the owner of the tty. */ |
| 203 | grp = getgrnam("tty"); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame] | 204 | gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid; |
| 205 | mode = (grp != NULL) ? 0622 : 0600; |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 206 | |
| 207 | /* |
| 208 | * Change owner and mode of the tty as required. |
| 209 | * Warn but continue if filesystem is read-only and the uids match/ |
| 210 | * tty is owned by root. |
| 211 | */ |
| 212 | if (stat(tty, &st)) |
| 213 | fatal("stat(%.100s) failed: %.100s", tty, |
| 214 | strerror(errno)); |
| 215 | |
| 216 | #ifdef WITH_SELINUX |
| 217 | ssh_selinux_setup_pty(pw->pw_name, tty); |
| 218 | #endif |
| 219 | |
| 220 | if (st.st_uid != pw->pw_uid || st.st_gid != gid) { |
| 221 | if (chown(tty, pw->pw_uid, gid) < 0) { |
| 222 | if (errno == EROFS && |
| 223 | (st.st_uid == pw->pw_uid || st.st_uid == 0)) |
| 224 | debug("chown(%.100s, %u, %u) failed: %.100s", |
| 225 | tty, (u_int)pw->pw_uid, (u_int)gid, |
| 226 | strerror(errno)); |
| 227 | else |
| 228 | fatal("chown(%.100s, %u, %u) failed: %.100s", |
| 229 | tty, (u_int)pw->pw_uid, (u_int)gid, |
| 230 | strerror(errno)); |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { |
| 235 | if (chmod(tty, mode) < 0) { |
| 236 | if (errno == EROFS && |
| 237 | (st.st_mode & (S_IRGRP | S_IROTH)) == 0) |
| 238 | debug("chmod(%.100s, 0%o) failed: %.100s", |
| 239 | tty, (u_int)mode, strerror(errno)); |
| 240 | else |
| 241 | fatal("chmod(%.100s, 0%o) failed: %.100s", |
| 242 | tty, (u_int)mode, strerror(errno)); |
| 243 | } |
| 244 | } |
| 245 | } |