/* Copyright (C) 1998, 2000, 2001, 2002 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <assert.h> #include <errno.h> #include <grp.h> #include <limits.h> #include <stdlib.h> #include <string.h> #include <sys/resource.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/wait.h> #include <unistd.h> #include "pty-private.h" /* Return the result of ptsname_r in the buffer pointed to by PTS, which should be of length BUF_LEN. If it is too long to fit in this buffer, a sufficiently long buffer is allocated using malloc, and returned in PTS. 0 is returned upon success, -1 otherwise. */ static int pts_name (int fd, char **pts, size_t buf_len) { int rv; char *buf = *pts; for (;;) { char *new_buf; if (buf_len) { rv = __ptsname_r (fd, buf, buf_len); if (rv != 0) { if (rv == ENOTTY) /* ptsname_r returns with ENOTTY to indicate a descriptor not referring to a pty master. For this condition, grantpt must return EINVAL. */ rv = EINVAL; errno = rv; /* Not necessarily set by __ptsname_r. */ break; } if (memchr (buf, '\0', buf_len)) /* We succeeded and the returned name fit in the buffer. */ break; /* Try again with a longer buffer. */ buf_len += buf_len; /* Double it */ } else /* No initial buffer; start out by mallocing one. */ buf_len = 128; /* First time guess. */ if (buf != *pts) /* We've already malloced another buffer at least once. */ new_buf = (char *) realloc (buf, buf_len); else new_buf = (char *) malloc (buf_len); if (! new_buf) { rv = -1; __set_errno (ENOMEM); break; } buf = new_buf; } if (rv == 0) *pts = buf; /* Return buffer to the user. */ else if (buf != *pts) free (buf); /* Free what we malloced when returning an error. */ return rv; } /* Change the ownership and access permission of the slave pseudo terminal associated with the master pseudo terminal specified by FD. */ int grantpt (int fd) { int retval = -1; #ifdef PATH_MAX char _buf[PATH_MAX]; #else char _buf[512]; #endif char *buf = _buf; struct stat64 st; char *grtmpbuf; struct group grbuf; size_t grbuflen = __sysconf (_SC_GETGR_R_SIZE_MAX); struct group *p; uid_t uid; gid_t gid; pid_t pid; if (pts_name (fd, &buf, sizeof (_buf))) return -1; if (__xstat64 (_STAT_VER, buf, &st) < 0) goto cleanup; /* Make sure that we own the device. */ uid = __getuid (); if (st.st_uid != uid) { if (__chown (buf, uid, st.st_gid) < 0) goto helper; } /* Get the group ID of the special `tty' group. */ if (grbuflen == (size_t) -1L) /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX. Try a moderate value. */ grbuflen = 1024; grtmpbuf = (char *) __alloca (grbuflen); __getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p); gid = p ? p->gr_gid : __getgid (); /* Make sure the group of the device is that special group. */ if (st.st_gid != gid) { if (__chown (buf, uid, gid) < 0) goto helper; } /* Make sure the permission mode is set to readable and writable by the owner, and writable by the group. */ if ((st.st_mode & ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP)) { if (__chmod (buf, S_IRUSR|S_IWUSR|S_IWGRP) < 0) goto helper; } retval = 0; goto cleanup; /* We have to use the helper program. */ helper: pid = __fork (); if (pid == -1) goto cleanup; else if (pid == 0) { /* Disable core dumps. */ struct rlimit rl = { 0, 0 }; __setrlimit (RLIMIT_CORE, &rl); /* We pass the master pseudo terminal as file descriptor PTY_FILENO. */ if (fd != PTY_FILENO) if (__dup2 (fd, PTY_FILENO) < 0) _exit (FAIL_EBADF); execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL); _exit (FAIL_EXEC); } else { int w; if (__waitpid (pid, &w, 0) == -1) goto cleanup; if (!WIFEXITED (w)) __set_errno (ENOEXEC); else switch (WEXITSTATUS(w)) { case 0: retval = 0; break; case FAIL_EBADF: __set_errno (EBADF); break; case FAIL_EINVAL: __set_errno (EINVAL); break; case FAIL_EACCES: __set_errno (EACCES); break; case FAIL_EXEC: __set_errno (ENOEXEC); break; default: assert(! "getpt: internal error: invalid exit code from pt_chown"); } } cleanup: if (buf != _buf) free (buf); return retval; }