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 1.1 2001/03/04 01:46:30 djm Exp $"); 16 17 #include <util.h> 18 #include "sshpty.h" 19 #include "log.h" 20 21 /* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */ 22 #if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY) 23 #undef HAVE_DEV_PTMX 24 #endif 25 26 #ifndef O_NOCTTY 27 #define O_NOCTTY 0 28 #endif 29 30 /* 31 * Allocates and opens a pty. Returns 0 if no pty could be allocated, or 32 * nonzero if a pty was successfully allocated. On success, open file 33 * descriptors for the pty and tty sides and the name of the tty side are 34 * returned (the buffer must be able to hold at least 64 characters). 35 */ 36 37 int 38 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen) 39 { 40 #if defined(HAVE_OPENPTY) || defined(BSD4_4) 41 /* openpty(3) exists in OSF/1 and some other os'es */ 42 char buf[64]; 43 int i; 44 45 i = openpty(ptyfd, ttyfd, buf, NULL, NULL); 46 if (i < 0) { 47 error("openpty: %.100s", strerror(errno)); 48 return 0; 49 } 50 strlcpy(namebuf, buf, namebuflen); /* possible truncation */ 51 return 1; 52 #else /* HAVE_OPENPTY */ 53 #ifdef HAVE__GETPTY 54 /* 55 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more 56 * pty's automagically when needed 57 */ 58 char *slave; 59 60 slave = _getpty(ptyfd, O_RDWR, 0622, 0); 61 if (slave == NULL) { 62 error("_getpty: %.100s", strerror(errno)); 63 return 0; 64 } 65 strlcpy(namebuf, slave, namebuflen); 66 /* Open the slave side. */ 67 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 68 if (*ttyfd < 0) { 69 error("%.200s: %.100s", namebuf, strerror(errno)); 70 close(*ptyfd); 71 return 0; 72 } 73 return 1; 74 #else /* HAVE__GETPTY */ 75 #ifdef HAVE_DEV_PTMX 76 /* 77 * This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3 78 * also has bsd-style ptys, but they simply do not work.) 79 */ 80 int ptm; 81 char *pts; 82 83 ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY); 84 if (ptm < 0) { 85 error("/dev/ptmx: %.100s", strerror(errno)); 86 return 0; 87 } 88 if (grantpt(ptm) < 0) { 89 error("grantpt: %.100s", strerror(errno)); 90 return 0; 91 } 92 if (unlockpt(ptm) < 0) { 93 error("unlockpt: %.100s", strerror(errno)); 94 return 0; 95 } 96 pts = ptsname(ptm); 97 if (pts == NULL) 98 error("Slave pty side name could not be obtained."); 99 strlcpy(namebuf, pts, namebuflen); 100 *ptyfd = ptm; 101 102 /* Open the slave side. */ 103 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 104 if (*ttyfd < 0) { 105 error("%.100s: %.100s", namebuf, strerror(errno)); 106 close(*ptyfd); 107 return 0; 108 } 109 /* Push the appropriate streams modules, as described in Solaris pts(7). */ 110 if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) 111 error("ioctl I_PUSH ptem: %.100s", strerror(errno)); 112 if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) 113 error("ioctl I_PUSH ldterm: %.100s", strerror(errno)); 114 if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) 115 error("ioctl I_PUSH ttcompat: %.100s", strerror(errno)); 116 return 1; 117 #else /* HAVE_DEV_PTMX */ 118 #ifdef HAVE_DEV_PTS_AND_PTC 119 /* AIX-style pty code. */ 120 const char *name; 121 122 *ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY); 123 if (*ptyfd < 0) { 124 error("Could not open /dev/ptc: %.100s", strerror(errno)); 125 return 0; 126 } 127 name = ttyname(*ptyfd); 128 if (!name) 129 fatal("Open of /dev/ptc returns device for which ttyname fails."); 130 strlcpy(namebuf, name, namebuflen); 131 *ttyfd = open(name, O_RDWR | O_NOCTTY); 132 if (*ttyfd < 0) { 133 error("Could not open pty slave side %.100s: %.100s", 134 name, strerror(errno)); 135 close(*ptyfd); 136 return 0; 137 } 138 return 1; 139 #else /* HAVE_DEV_PTS_AND_PTC */ 140 /* BSD-style pty code. */ 141 char buf[64]; 142 int i; 143 const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ"; 144 const char *ptyminors = "0123456789abcdef"; 145 int num_minors = strlen(ptyminors); 146 int num_ptys = strlen(ptymajors) * num_minors; 147 148 for (i = 0; i < num_ptys; i++) { 149 snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors], 150 ptyminors[i % num_minors]); 151 *ptyfd = open(buf, O_RDWR | O_NOCTTY); 152 if (*ptyfd < 0) 153 continue; 154 snprintf(namebuf, namebuflen, "/dev/tty%c%c", 155 ptymajors[i / num_minors], ptyminors[i % num_minors]); 156 157 /* Open the slave side. */ 158 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 159 if (*ttyfd < 0) { 160 error("%.100s: %.100s", namebuf, strerror(errno)); 161 close(*ptyfd); 162 return 0; 163 } 164 return 1; 165 } 166 return 0; 167 #endif /* HAVE_DEV_PTS_AND_PTC */ 168 #endif /* HAVE_DEV_PTMX */ 169 #endif /* HAVE__GETPTY */ 170 #endif /* HAVE_OPENPTY */ 171 } 172 173 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ 174 175 void 176 pty_release(const char *ttyname) 177 { 178 if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0) 179 error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno)); 180 if (chmod(ttyname, (mode_t) 0666) < 0) 181 error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno)); 182 } 183 184 /* Makes the tty the processes controlling tty and sets it to sane modes. */ 185 186 void 187 pty_make_controlling_tty(int *ttyfd, const char *ttyname) 188 { 189 int fd; 190 191 /* First disconnect from the old controlling tty. */ 192 #ifdef TIOCNOTTY 193 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 194 if (fd >= 0) { 195 (void) ioctl(fd, TIOCNOTTY, NULL); 196 close(fd); 197 } 198 #endif /* TIOCNOTTY */ 199 if (setsid() < 0) 200 error("setsid: %.100s", strerror(errno)); 201 202 /* 203 * Verify that we are successfully disconnected from the controlling 204 * tty. 205 */ 206 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 207 if (fd >= 0) { 208 error("Failed to disconnect from controlling tty."); 209 close(fd); 210 } 211 /* Make it our controlling tty. */ 212 #ifdef TIOCSCTTY 213 debug("Setting controlling tty using TIOCSCTTY."); 214 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) 215 error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); 216 #endif /* TIOCSCTTY */ 217 fd = open(ttyname, O_RDWR); 218 if (fd < 0) 219 error("%.100s: %.100s", ttyname, strerror(errno)); 220 else 221 close(fd); 222 223 /* Verify that we now have a controlling tty. */ 224 fd = open(_PATH_TTY, O_WRONLY); 225 if (fd < 0) 226 error("open /dev/tty failed - could not set controlling tty: %.100s", 227 strerror(errno)); 228 else { 229 close(fd); 230 } 231 } 232 233 /* Changes the window size associated with the pty. */ 234 235 void 236 pty_change_window_size(int ptyfd, int row, int col, 237 int xpixel, int ypixel) 238 { 239 struct winsize w; 240 w.ws_row = row; 241 w.ws_col = col; 242 w.ws_xpixel = xpixel; 243 w.ws_ypixel = ypixel; 244 (void) ioctl(ptyfd, TIOCSWINSZ, &w); 245 } 246 247 void 248 pty_setowner(struct passwd *pw, const char *ttyname) 249 { 250 struct group *grp; 251 gid_t gid; 252 mode_t mode; 253 struct stat st; 254 255 /* Determine the group to make the owner of the tty. */ 256 grp = getgrnam("tty"); 257 if (grp) { 258 gid = grp->gr_gid; 259 mode = S_IRUSR | S_IWUSR | S_IWGRP; 260 } else { 261 gid = pw->pw_gid; 262 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; 263 } 264 265 /* 266 * Change owner and mode of the tty as required. 267 * Warn but continue if filesystem is read-only and the uids match. 268 */ 269 if (stat(ttyname, &st)) 270 fatal("stat(%.100s) failed: %.100s", ttyname, 271 strerror(errno)); 272 273 if (st.st_uid != pw->pw_uid || st.st_gid != gid) { 274 if (chown(ttyname, pw->pw_uid, gid) < 0) { 275 if (errno == EROFS && st.st_uid == pw->pw_uid) 276 error("chown(%.100s, %d, %d) failed: %.100s", 277 ttyname, pw->pw_uid, gid, 278 strerror(errno)); 279 else 280 fatal("chown(%.100s, %d, %d) failed: %.100s", 281 ttyname, pw->pw_uid, gid, 282 strerror(errno)); 283 } 284 } 285 286 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { 287 if (chmod(ttyname, mode) < 0) { 288 if (errno == EROFS && 289 (st.st_mode & (S_IRGRP | S_IROTH)) == 0) 290 error("chmod(%.100s, 0%o) failed: %.100s", 291 ttyname, mode, strerror(errno)); 292 else 293 fatal("chmod(%.100s, 0%o) failed: %.100s", 294 ttyname, mode, strerror(errno)); 295 } 296 } 297 } 298