/* $OpenBSD: sshpty.c,v 1.31 2016/11/29 03:54:50 dtucker Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * Allocating a pseudo-terminal, and making it the controlling tty. * * As far as I am concerned, the code I have written for this software * can be used freely for any purpose. Any derived versions of this * software must be clearly marked as such, and if the derived work is * incompatible with the protocol description in the RFC file, it must be * called by a name other than "ssh" or "Secure Shell". */ #include "includes.h" #include #include #include #include #include #include #include #ifdef HAVE_PATHS_H # include #endif #include #include #include #include #ifdef HAVE_UTIL_H # include #endif #include #include "sshpty.h" #include "log.h" #include "misc.h" #ifdef HAVE_PTY_H # include #endif #ifndef O_NOCTTY #define O_NOCTTY 0 #endif #ifdef __APPLE__ # include # if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5) # define __APPLE_PRIVPTY__ # endif #endif /* * Allocates and opens a pty. Returns 0 if no pty could be allocated, or * nonzero if a pty was successfully allocated. On success, open file * descriptors for the pty and tty sides and the name of the tty side are * returned (the buffer must be able to hold at least 64 characters). */ int pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen) { /* openpty(3) exists in OSF/1 and some other os'es */ char *name; int i; i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); if (i < 0) { error("openpty: %.100s", strerror(errno)); return 0; } #ifdef ANDROID if (ptsname_r(*ptyfd, namebuf, namebuflen)) { fatal("openpty ptsname failed."); close(*ptyfd); *ptyfd = -1; return -1; } return 1; #else name = ttyname(*ttyfd); if (!name) fatal("openpty returns device for which ttyname fails."); strlcpy(namebuf, name, namebuflen); /* possible truncation */ return 1; #endif } /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ void pty_release(const char *tty) { #if !defined(__APPLE_PRIVPTY__) && !defined(HAVE_OPENPTY) if (chown(tty, (uid_t) 0, (gid_t) 0) < 0) error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); if (chmod(tty, (mode_t) 0666) < 0) error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno)); #endif /* !__APPLE_PRIVPTY__ && !HAVE_OPENPTY */ } /* Makes the tty the process's controlling tty and sets it to sane modes. */ void pty_make_controlling_tty(int *ttyfd, const char *tty) { int fd; #ifdef _UNICOS if (setsid() < 0) error("setsid: %.100s", strerror(errno)); fd = open(tty, O_RDWR|O_NOCTTY); if (fd != -1) { signal(SIGHUP, SIG_IGN); ioctl(fd, TCVHUP, (char *)NULL); signal(SIGHUP, SIG_DFL); setpgid(0, 0); close(fd); } else { error("Failed to disconnect from controlling tty."); } debug("Setting controlling tty using TCSETCTTY."); ioctl(*ttyfd, TCSETCTTY, NULL); fd = open("/dev/tty", O_RDWR); if (fd < 0) error("%.100s: %.100s", tty, strerror(errno)); close(*ttyfd); *ttyfd = fd; #else /* _UNICOS */ /* First disconnect from the old controlling tty. */ #ifdef TIOCNOTTY fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); if (fd >= 0) { (void) ioctl(fd, TIOCNOTTY, NULL); close(fd); } #endif /* TIOCNOTTY */ if (setsid() < 0) error("setsid: %.100s", strerror(errno)); /* * Verify that we are successfully disconnected from the controlling * tty. */ fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); if (fd >= 0) { error("Failed to disconnect from controlling tty."); close(fd); } /* Make it our controlling tty. */ #ifdef TIOCSCTTY debug("Setting controlling tty using TIOCSCTTY."); if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); #endif /* TIOCSCTTY */ #ifdef NEED_SETPGRP if (setpgrp(0,0) < 0) error("SETPGRP %s",strerror(errno)); #endif /* NEED_SETPGRP */ fd = open(tty, O_RDWR); if (fd < 0) error("%.100s: %.100s", tty, strerror(errno)); else close(fd); /* Verify that we now have a controlling tty. */ fd = open(_PATH_TTY, O_WRONLY); if (fd < 0) error("open /dev/tty failed - could not set controlling tty: %.100s", strerror(errno)); else close(fd); #endif /* _UNICOS */ } /* Changes the window size associated with the pty. */ void pty_change_window_size(int ptyfd, u_int row, u_int col, u_int xpixel, u_int ypixel) { struct winsize w; /* may truncate u_int -> u_short */ w.ws_row = row; w.ws_col = col; w.ws_xpixel = xpixel; w.ws_ypixel = ypixel; (void) ioctl(ptyfd, TIOCSWINSZ, &w); } void pty_setowner(struct passwd *pw, const char *tty) { struct group *grp; gid_t gid; mode_t mode; struct stat st; /* Determine the group to make the owner of the tty. */ grp = getgrnam("tty"); gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid; mode = (grp != NULL) ? 0620 : 0600; /* * Change owner and mode of the tty as required. * Warn but continue if filesystem is read-only and the uids match/ * tty is owned by root. */ if (stat(tty, &st)) fatal("stat(%.100s) failed: %.100s", tty, strerror(errno)); #ifdef WITH_SELINUX ssh_selinux_setup_pty(pw->pw_name, tty); #endif if (st.st_uid != pw->pw_uid || st.st_gid != gid) { if (chown(tty, pw->pw_uid, gid) < 0) { if (errno == EROFS && (st.st_uid == pw->pw_uid || st.st_uid == 0)) debug("chown(%.100s, %u, %u) failed: %.100s", tty, (u_int)pw->pw_uid, (u_int)gid, strerror(errno)); else fatal("chown(%.100s, %u, %u) failed: %.100s", tty, (u_int)pw->pw_uid, (u_int)gid, strerror(errno)); } } if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { if (chmod(tty, mode) < 0) { if (errno == EROFS && (st.st_mode & (S_IRGRP | S_IROTH)) == 0) debug("chmod(%.100s, 0%o) failed: %.100s", tty, (u_int)mode, strerror(errno)); else fatal("chmod(%.100s, 0%o) failed: %.100s", tty, (u_int)mode, strerror(errno)); } } } /* Disconnect from the controlling tty. */ void disconnect_controlling_tty(void) { #ifdef TIOCNOTTY int fd; if ((fd = open(_PATH_TTY, O_RDWR | O_NOCTTY)) >= 0) { (void) ioctl(fd, TIOCNOTTY, NULL); close(fd); } #endif /* TIOCNOTTY */ }