drop_privileges.c

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/* SPDX-FileCopyrightText: 2010-2023 Greenbone AG
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */
 
#include "drop_privileges.h"
 
#include <grp.h> /* for initgroups */
#include <pwd.h> /* for passwd, getpwnam */
#include <sys/types.h>
#include <unistd.h> /* for geteuid, setgid, setuid */
 
#undef G_LOG_DOMAIN
 
#define G_LOG_DOMAIN "libgvm base"
 
static gint
drop_privileges_error (GError **error, gint errorcode, const gchar *message)
{
  g_set_error (error, GVM_DROP_PRIVILEGES, errorcode, "%s", message);
  return errorcode;
}
 
int
drop_privileges (gchar *username, GError **error)
{
  g_return_val_if_fail (*error == NULL, GVM_DROP_PRIVILEGES_ERROR_ALREADY_SET);
 
  if (username == NULL)
    username = "nobody";
 
  if (geteuid () == 0)
    {
      struct passwd *user_pw = NULL;
 
      if ((user_pw = getpwnam (username)))
        {
          if (initgroups (username, user_pw->pw_gid) != 0)
            return drop_privileges_error (
              error, GVM_DROP_PRIVILEGES_FAIL_SUPPLEMENTARY,
              "Failed to drop supplementary groups privileges!\n");
          if (setgid (user_pw->pw_gid) != 0)
            return drop_privileges_error (error,
                                          GVM_DROP_PRIVILEGES_FAIL_DROP_GID,
                                          "Failed to drop group privileges!\n");
          if (setuid (user_pw->pw_uid) != 0)
            return drop_privileges_error (error,
                                          GVM_DROP_PRIVILEGES_FAIL_DROP_UID,
                                          "Failed to drop user privileges!\n");
        }
      else
        {
          g_set_error (error, GVM_DROP_PRIVILEGES,
                       GVM_DROP_PRIVILEGES_FAIL_UNKNOWN_USER,
                       "Failed to get gid and uid for user %s.", username);
          return GVM_DROP_PRIVILEGES_FAIL_UNKNOWN_USER;
        }
      return GVM_DROP_PRIVILEGES_OK;
    }
  else
    {
      return drop_privileges_error (error, GVM_DROP_PRIVILEGES_FAIL_NOT_ROOT,
                                    "Only root can drop its privileges.");
    }
}