/* * Copyright (c) 2002 The FreeBSD Project, Inc. * All rights reserved. * * This software includes code contributed to the FreeBSD Project * by Ryan Younce of North Carolina State University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the FreeBSD Project nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS'' * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include <sys/cdefs.h> #ifndef lint __FBSDID("$FreeBSD: src/lib/libc/stdlib/grantpt.c,v 1.2 2003/01/04 08:10:55 tjr Exp $"); #endif /* not lint */ #include "namespace.h" #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <sys/time.h> #include <sys/resource.h> #include <errno.h> #include <fcntl.h> #include <grp.h> #include <paths.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sysexits.h> #include <unistd.h> #include "un-namespace.h" #define PTM_MAJOR 6 /* pseudo tty master major */ #define PTS_MAJOR 5 /* pseudo tty slave major */ #define PTM_PREFIX "pty" /* pseudo tty master naming convention */ #define PTS_PREFIX "tty" /* pseudo tty slave naming convention */ /* * The following are range values for pseudo TTY devices. Pseudo TTYs have a * name of /dev/[pt]ty[p-sP-S][0-9a-v], yielding 256 combinations per major. */ #define PT_MAX 256 #define PT_DEV1 "pqrsPQRS" #define PT_DEV2 "0123456789abcdefghijklmnopqrstuv" /* * grantpt(3) support utility. */ #define _PATH_PTCHOWN "/usr/libexec/pt_chown" /* * ISPTM(x) returns 0 for struct stat x if x is not a pty master. * The bounds checking may be unnecessary but it does eliminate doubt. */ #define ISPTM(x) (S_ISCHR((x).st_mode) && \ major((x).st_rdev) == PTM_MAJOR && \ minor((x).st_rdev) >= 0 && \ minor((x).st_rdev) < PT_MAX) /* * grantpt(): grant ownership of a slave pseudo-terminal device to the * current user. */ int grantpt(int fildes) { int retval, serrno, status; pid_t pid, spid; gid_t gid; char *slave; sigset_t oblock, nblock; struct group *grp; retval = -1; serrno = errno; if ((slave = ptsname(fildes)) != NULL) { /* * Block SIGCHLD. */ (void)sigemptyset(&nblock); (void)sigaddset(&nblock, SIGCHLD); (void)_sigprocmask(SIG_BLOCK, &nblock, &oblock); switch (pid = fork()) { case -1: break; case 0: /* child */ /* * pt_chown expects the master pseudo TTY to be its * standard input. */ (void)_dup2(fildes, STDIN_FILENO); (void)_sigprocmask(SIG_SETMASK, &oblock, NULL); execl(_PATH_PTCHOWN, _PATH_PTCHOWN, (char *)NULL); _exit(EX_UNAVAILABLE); /* NOTREACHED */ default: /* parent */ /* * Just wait for the process. Error checking is * done below. */ while ((spid = _waitpid(pid, &status, 0)) == -1 && (errno == EINTR)) ; if (spid != -1 && WIFEXITED(status) && WEXITSTATUS(status) == EX_OK) retval = 0; else errno = EACCES; break; } /* * Restore process's signal mask. */ (void)_sigprocmask(SIG_SETMASK, &oblock, NULL); if (retval) { /* * pt_chown failed. Try to manually change the * permissions for the slave. */ gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1; if (chown(slave, getuid(), gid) == -1 || chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == -1) errno = EACCES; else retval = 0; } } if (!retval) errno = serrno; return (retval); } /* * posix_openpt(): open the first available master pseudo-terminal device * and return descriptor. */ int posix_openpt(int oflag) { char *mc1, *mc2, master[] = _PATH_DEV PTM_PREFIX "XY"; const char *pc1, *pc2; int fildes, bflag, serrno; fildes = -1; bflag = 0; serrno = errno; /* * Check flag validity. POSIX doesn't require it, * but we still do so. */ if (oflag & ~(O_RDWR | O_NOCTTY)) errno = EINVAL; else { mc1 = master + strlen(_PATH_DEV PTM_PREFIX); mc2 = mc1 + 1; /* Cycle through all possible master PTY devices. */ for (pc1 = PT_DEV1; !bflag && (*mc1 = *pc1); ++pc1) for (pc2 = PT_DEV2; (*mc2 = *pc2) != '\0'; ++pc2) { /* * Break out if we successfully open a PTY, * or if open() fails due to limits. */ if ((fildes = _open(master, oflag)) != -1 || (errno == EMFILE || errno == ENFILE)) { ++bflag; break; } } if (fildes != -1) errno = serrno; else if (!bflag) errno = EAGAIN; } return (fildes); } /* * ptsname(): return the pathname of the slave pseudo-terminal device * associated with the specified master. */ char * ptsname(int fildes) { static char slave[] = _PATH_DEV PTS_PREFIX "XY"; char *retval; struct stat sbuf; retval = NULL; if (_fstat(fildes, &sbuf) == 0) { if (!ISPTM(sbuf)) errno = EINVAL; else { (void)sprintf(slave, _PATH_DEV PTS_PREFIX "%c%c", PT_DEV1[minor(sbuf.st_rdev) / 32], PT_DEV2[minor(sbuf.st_rdev) % 32]); retval = slave; } } return (retval); } /* * unlockpt(): unlock a pseudo-terminal device pair. */ int unlockpt(int fildes) { int retval; struct stat sbuf; /* * Unlocking a master/slave pseudo-terminal pair has no meaning in a * non-streams PTY environment. However, we do ensure fildes is a * valid master pseudo-terminal device. */ if ((retval = _fstat(fildes, &sbuf)) == 0 && !ISPTM(sbuf)) { errno = EINVAL; retval = -1; } return (retval); }