219 lines
5.2 KiB
C
219 lines
5.2 KiB
C
/* ufopen.c
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Open a file with the permissions of the invoking user.
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Copyright (C) 1992 Ian Lance Taylor
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This file is part of the Taylor UUCP package.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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The author of the program may be contacted at ian@airs.com or
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c/o Infinity Development Systems, P.O. Box 520, Waltham, MA 02254.
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*/
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#include "uucp.h"
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#include "uudefs.h"
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#include "sysdep.h"
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#include "system.h"
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#include <errno.h>
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#if HAVE_FCNTL_H
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#include <fcntl.h>
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#else
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#if HAVE_SYS_FILE_H
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#include <sys/file.h>
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#endif
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#endif
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#ifndef O_RDONLY
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#define O_RDONLY 0
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#define O_WRONLY 1
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#define O_RDWR 2
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#endif
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#ifndef O_NOCTTY
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#define O_NOCTTY 0
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#endif
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#ifndef FD_CLOEXEC
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#define FD_CLOEXEC 1
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#endif
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/* Local functions. */
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static boolean fsuser_perms P((uid_t *pieuid));
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static boolean fsuucp_perms P((long ieuid));
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/* Switch to permissions of the invoking user. */
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static boolean
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fsuser_perms (pieuid)
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uid_t *pieuid;
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{
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uid_t ieuid, iuid;
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ieuid = geteuid ();
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iuid = getuid ();
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if (pieuid != NULL)
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*pieuid = ieuid;
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#if HAVE_SETREUID
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/* Swap the effective user id and the real user id. We can then
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swap them back again when we want to return to the uucp user's
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permissions. */
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if (setreuid (ieuid, iuid) < 0)
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{
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ulog (LOG_ERROR, "setreuid (%ld, %ld): %s",
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(long) ieuid, (long) iuid, strerror (errno));
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return FALSE;
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}
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#else /* ! HAVE_SETREUID */
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#if HAVE_SAVED_SETUID
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/* Set the effective user id to the real user id. Since the
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effective user id is saved (it's the saved setuid) we will able
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to set back to it later. If the real user id is root we will not
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be able to switch back and forth, so don't even try. */
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if (iuid != 0)
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{
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if (setuid (iuid) < 0)
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{
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ulog (LOG_ERROR, "setuid (%ld): %s", (long) iuid, strerror (errno));
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return FALSE;
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}
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}
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#else /* ! HAVE_SAVED_SETUID */
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/* There's no way to switch between real permissions and effective
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permissions. Just try to open the file with the uucp
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permissions. */
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#endif /* ! HAVE_SAVED_SETUID */
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#endif /* ! HAVE_SETREUID */
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return TRUE;
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}
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/* Restore the uucp permissions. */
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/*ARGSUSED*/
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static boolean
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fsuucp_perms (ieuid)
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long ieuid;
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{
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#if HAVE_SETREUID
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/* Swap effective and real user id's back to what they were. */
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if (! fsuser_perms ((uid_t *) NULL))
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return FALSE;
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#else /* ! HAVE_SETREUID */
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#if HAVE_SAVED_SETUID
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/* Set ourselves back to our original effective user id. */
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if (setuid ((uid_t) ieuid) < 0)
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{
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ulog (LOG_ERROR, "setuid (%ld): %s", (long) ieuid, strerror (errno));
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/* Is this error message helpful or confusing? */
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if (errno == EPERM)
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ulog (LOG_ERROR,
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"Probably HAVE_SAVED_SETUID in policy.h should be set to 0");
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return FALSE;
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}
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#else /* ! HAVE_SAVED_SETUID */
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/* We didn't switch, no need to switch back. */
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#endif /* ! HAVE_SAVED_SETUID */
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#endif /* ! HAVE_SETREUID */
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return TRUE;
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}
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/* Open a file with the permissions of the invoking user. Ignore the
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fbinary argument since Unix has no distinction between text and
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binary files. */
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/*ARGSUSED*/
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openfile_t
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esysdep_user_fopen (zfile, frd, fbinary)
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const char *zfile;
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boolean frd;
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boolean fbinary;
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{
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uid_t ieuid;
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openfile_t e;
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const char *zerr;
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int o = 0;
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if (! fsuser_perms (&ieuid))
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return EFILECLOSED;
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zerr = NULL;
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#if USE_STDIO
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e = fopen (zfile, frd ? "r" : "w");
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if (e == NULL)
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zerr = "fopen";
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else
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o = fileno (e);
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#else
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if (frd)
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{
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e = open ((char *) zfile, O_RDONLY | O_NOCTTY, 0);
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zerr = "open";
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}
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else
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{
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e = creat ((char *) zfile, IPUBLIC_FILE_MODE);
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zerr = "creat";
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}
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if (e >= 0)
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{
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o = e;
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zerr = NULL;
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}
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#endif
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if (! fsuucp_perms ((long) ieuid))
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{
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if (ffileisopen (e))
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(void) ffileclose (e);
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return EFILECLOSED;
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}
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if (zerr != NULL)
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{
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ulog (LOG_ERROR, "%s (%s): %s", zerr, zfile, strerror (errno));
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#if ! HAVE_SETREUID
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/* Are these error messages helpful or confusing? */
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#if HAVE_SAVED_SETUID
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if (errno == EACCES && getuid () == 0)
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ulog (LOG_ERROR,
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"The superuser may only transfer files that are readable by %s",
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OWNER);
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#else
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if (errno == EACCES)
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ulog (LOG_ERROR,
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"You may only transfer files that are readable by %s", OWNER);
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#endif
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#endif /* ! HAVE_SETREUID */
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return EFILECLOSED;
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}
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if (fcntl (o, F_SETFD, fcntl (o, F_GETFD, 0) | FD_CLOEXEC) < 0)
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{
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ulog (LOG_ERROR, "fcntl (FD_CLOEXEC): %s", strerror (errno));
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(void) ffileclose (e);
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return EFILECLOSED;
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}
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return e;
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}
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