server/usergroup.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <stdarg.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 #include <errno.h>
  41 #include <sys/types.h>
  42
  43 #ifdef HAVE_PWD_H
  44 #include <pwd.h>
  45 #endif
  46
  47 #ifdef HAVE_GRP_H
  48 #include <grp.h>
  49 #endif
  50
  51 #include "internal.h"
  52
  53 #if defined (HAVE_PWD_H) && defined (HAVE_GRP_H)
  54
  55 static uid_t parseuser (const char *);
  56 static gid_t parsegroup (const char *);
  57
  58 /* Handle the -u and -g options.  If user and group are non-NULL
  59  * then this parses them to work out the UID/GID and changes
  60  * user and group.
  61  */
  62 void
  63 change_user (void)
  64 {
  65   if (group) {
  66     gid_t gid = parsegroup (group);
  67
  68     if (setgid (gid) == -1) {
  69       perror ("setgid");
  70       exit (EXIT_FAILURE);
  71     }
  72
  73     /* Kill supplemental groups from parent process. */
  74     if (setgroups (1, &gid) == -1) {
  75       perror ("setgroups");
  76       exit (EXIT_FAILURE);
  77     }
  78
  79     debug ("changed group to %s", group);
  80   }
  81
  82   if (user) {
  83     uid_t uid = parseuser (user);
  84
  85     if (setuid (uid) == -1) {
  86       perror ("setuid");
  87       exit (EXIT_FAILURE);
  88     }
  89
  90     debug ("changed user to %s", user);
  91   }
  92 }
  93
  94 static uid_t
  95 parseuser (const char *id)
  96 {
  97   struct passwd *pwd;
  98   int saved_errno;
  99
 100   errno = 0;
 101   pwd = getpwnam (id);
 102
 103   if (NULL == pwd) {
 104     int val;
 105
 106     saved_errno = errno;
 107
 108     if (nbdkit_parse_int ("parseuser", id, &val) == 0)
 109       return val;
 110
 111     fprintf (stderr, "%s: -u option: %s is not a valid user name or uid",
 112              program_name, id);
 113     if (saved_errno != 0)
 114       fprintf (stderr, " (getpwnam error: %s)", strerror (saved_errno));
 115     fprintf (stderr, "\n");
 116     exit (EXIT_FAILURE);
 117   }
 118
 119   return pwd->pw_uid;
 120 }
 121
 122 static gid_t
 123 parsegroup (const char *id)
 124 {
 125   struct group *grp;
 126   int saved_errno;
 127
 128   errno = 0;
 129   grp = getgrnam (id);
 130
 131   if (NULL == grp) {
 132     int val;
 133
 134     saved_errno = errno;
 135
 136     if (nbdkit_parse_int ("parsegroup", id, &val) == 0)
 137       return val;
 138
 139     fprintf (stderr, "%s: -g option: %s is not a valid group name or gid",
 140              program_name, id);
 141     if (saved_errno != 0)
 142       fprintf (stderr, " (getgrnam error: %s)", strerror (saved_errno));
 143     fprintf (stderr, "\n");
 144     exit (EXIT_FAILURE);
 145   }
 146
 147   return grp->gr_gid;
 148 }
 149
 150 #else /* a platform like Windows which lacks pwd/grp functions */
 151
 152 void
 153 change_user (void)
 154 {
 155   if (!user && !group)
 156     return;
 157
 158   NOT_IMPLEMENTED_ON_WINDOWS ("--user/--group");
 159 }
 160
 161 #endif