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Diffstat (limited to '')
| -rw-r--r-- | sshpty.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/sshpty.c b/sshpty.c new file mode 100644 index 0000000..cae0b97 --- /dev/null +++ b/sshpty.c @@ -0,0 +1,232 @@ +/* $OpenBSD: sshpty.c,v 1.34 2019/07/04 16:20:10 deraadt Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, 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 <sys/types.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <signal.h> + +#include <errno.h> +#include <fcntl.h> +#include <grp.h> +#ifdef HAVE_PATHS_H +# include <paths.h> +#endif +#include <pwd.h> +#include <stdarg.h> +#include <stdio.h> +#include <string.h> +#include <termios.h> +#ifdef HAVE_UTIL_H +# include <util.h> +#endif +#include <unistd.h> + +#include "sshpty.h" +#include "log.h" +#include "misc.h" + +#ifdef HAVE_PTY_H +# include <pty.h> +#endif + +#ifndef O_NOCTTY +#define O_NOCTTY 0 +#endif + +#ifdef __APPLE__ +# include <AvailabilityMacros.h> +# 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 == -1) { + error("openpty: %.100s", strerror(errno)); + return 0; + } + name = ttyname(*ttyfd); + if (!name) + fatal("openpty returns device for which ttyname fails."); + + strlcpy(namebuf, name, namebuflen); /* possible truncation */ + return 1; +} + +/* 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) == -1) + error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno)); + if (chmod(tty, (mode_t) 0666) == -1) + 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; + + /* 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() == -1) + 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 == -1) + 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 == -1) + error("open /dev/tty failed - could not set controlling tty: %.100s", + strerror(errno)); + else + close(fd); +} + +/* 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"); + if (grp == NULL) + debug("%s: no tty group", __func__); + 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) == -1) + 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) == -1) { + 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) == -1) { + 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 */ +} |