dma-mbox-create.c

   1 /*
   2  * Copyright (c) 2010-2014, Simon Schubert <2@0x2c.org>.
   3  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to The DragonFly Project
   6  * by Simon Schubert <2@0x2c.org>.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 /*
  37  * This binary is setuid root.  Use extreme caution when touching
  38  * user-supplied information.  Keep the root window as small as possible.
  39  */
  40
  41 #include <sys/param.h>
  42 #include <sys/stat.h>
  43
  44 #include <errno.h>
  45 #include <fcntl.h>
  46 #include <grp.h>
  47 #include <paths.h>
  48 #include <pwd.h>
  49 #include <stdio.h>
  50 #include <syslog.h>
  51 #include <unistd.h>
  52
  53 #include "dma.h"
  54
  55
  56 static void
  57 logfail(int exitcode, const char *fmt, ...)
  58 {
  59         int oerrno = errno;
  60         va_list ap;
  61         char outs[1024];
  62
  63         outs[0] = 0;
  64         if (fmt != NULL) {
  65                 va_start(ap, fmt);
  66                 vsnprintf(outs, sizeof(outs), fmt, ap);
  67                 va_end(ap);
  68         }
  69
  70         errno = oerrno;
  71         if (*outs != 0)
  72                 syslog(LOG_ERR, errno ? "%s: %m" : "%s", outs);
  73         else
  74                 syslog(LOG_ERR, errno ? "%m" : "unknown error");
  75
  76         exit(exitcode);
  77 }
  78
  79 /*
  80  * Create a mbox in /var/mail for a given user, or make sure
  81  * the permissions are correct for dma.
  82  */
  83
  84 int
  85 main(int argc, char **argv)
  86 {
  87         const char *user;
  88         struct passwd *pw;
  89         struct group *gr;
  90         uid_t user_uid;
  91         gid_t mail_gid;
  92         int f, maildirfd;
  93
  94         openlog("dma-mbox-create", 0, LOG_MAIL);
  95
  96         errno = 0;
  97         gr = getgrnam(DMA_GROUP);
  98         if (!gr)
  99                 logfail(EX_CONFIG, "cannot find dma group `%s'", DMA_GROUP);
 100
 101         mail_gid = gr->gr_gid;
 102
 103         if (setgid(mail_gid) != 0)
 104                 logfail(EX_NOPERM, "cannot set gid to %d (%s)", mail_gid, DMA_GROUP);
 105         if (getegid() != mail_gid)
 106                 logfail(EX_NOPERM, "cannot set gid to %d (%s), still at %d", mail_gid, DMA_GROUP, getegid());
 107
 108         /*
 109          * We take exactly one argument: the username.
 110          */
 111         if (argc != 2) {
 112                 errno = 0;
 113                 logfail(EX_USAGE, "no arguments");
 114         }
 115         user = argv[1];
 116
 117         syslog(LOG_NOTICE, "creating mbox for `%s'", user);
 118
 119         /* the username may not contain a pathname separator */
 120         if (strchr(user, '/')) {
 121                 errno = 0;
 122                 logfail(EX_DATAERR, "path separator in username `%s'", user);
 123                 exit(1);
 124         }
 125
 126         /* verify the user exists */
 127         errno = 0;
 128         pw = getpwnam(user);
 129         if (!pw)
 130                 logfail(EX_NOUSER, "cannot find user `%s'", user);
 131
 132         maildirfd = open(_PATH_MAILDIR, O_RDONLY);
 133         if (maildirfd < 0)
 134                 logfail(EX_NOINPUT, "cannot open maildir %s", _PATH_MAILDIR);
 135
 136         user_uid = pw->pw_uid;
 137
 138         f = openat(maildirfd, user, O_RDONLY|O_CREAT|O_NOFOLLOW, 0600);
 139         if (f < 0)
 140                 logfail(EX_NOINPUT, "cannot open mbox `%s'", user);
 141
 142         if (fchown(f, user_uid, mail_gid))
 143                 logfail(EX_OSERR, "cannot change owner of mbox `%s'", user);
 144
 145         if (fchmod(f, 0620))
 146                 logfail(EX_OSERR, "cannot change permissions of mbox `%s'",
 147                     user);
 148
 149         /* file should be present with the right owner and permissions */
 150
 151         syslog(LOG_NOTICE, "successfully created mbox for `%s'", user);
 152
 153         return (0);
 154 }