/* * Part of Very Secure FTPd * Licence: GPL v2 * Author: Chris Evans * postprivparent.c * * This file contains all privileged parent services offered after logging * in. This includes e.g. chown() of uploaded files, issuing of port 20 * sockets. */#include "postprivparent.h"#include "session.h"#include "privops.h"#include "privsock.h"#include "utility.h"#include "tunables.h"#include "defs.h"#include "sysutil.h"#include "str.h"#include "secutil.h"#include "sysstr.h"#include "sysdeputil.h"static void minimize_privilege(struct vsf_session* p_sess);static void process_post_login_req(struct vsf_session* p_sess);static void cmd_process_chown(struct vsf_session* p_sess);static void cmd_process_get_data_sock(struct vsf_session* p_sess);voidvsf_priv_parent_postlogin(struct vsf_session* p_sess){  minimize_privilege(p_sess);  /* We're still here... */  while (1)  {    process_post_login_req(p_sess);  }}static voidprocess_post_login_req(struct vsf_session* p_sess){  char cmd;  vsf_sysutil_unblock_sig(kVSFSysUtilSigCHLD);  /* Blocks */  cmd = priv_sock_get_cmd(p_sess->parent_fd);  vsf_sysutil_block_sig(kVSFSysUtilSigCHLD);  if (tunable_chown_uploads && cmd == PRIV_SOCK_CHOWN)  {    cmd_process_chown(p_sess);  }  else if (tunable_connect_from_port_20 && cmd == PRIV_SOCK_GET_DATA_SOCK)  {    cmd_process_get_data_sock(p_sess);  }  else  {    die("bad request in process_post_login_req");  }}static voidminimize_privilege(struct vsf_session* p_sess){  /* So, we logged in and forked a totally unprivileged child. Our job   * now is to minimize the privilege we need in order to act as a helper   * to the child.   *   * In some happy circumstances, we can exit and be done with root   * altogether.   */  if (!p_sess->is_anonymous && tunable_session_support)  {    /* Need to hang around to update logs, utmp, wtmp etc. on logout.     * Need to keep privs to do this. */    return;  }  if (!tunable_chown_uploads && !tunable_connect_from_port_20 &&      !tunable_max_per_ip && !tunable_max_clients)  {    /* Cool. We're outta here. */    vsf_sysutil_exit(0);  }  {    unsigned int caps = 0;    struct mystr user_str = INIT_MYSTR;    struct mystr dir_str = INIT_MYSTR;    str_alloc_text(&user_str, tunable_nopriv_user);    str_alloc_text(&dir_str, tunable_secure_chroot_dir);    if (tunable_chown_uploads)    {      caps |= kCapabilityCAP_CHOWN;    }    if (tunable_connect_from_port_20)    {      caps |= kCapabilityCAP_NET_BIND_SERVICE;    }    vsf_secutil_change_credentials(&user_str, &dir_str, 0, caps,                                   VSF_SECUTIL_OPTION_CHROOT);    str_free(&user_str);    str_free(&dir_str);  }}static voidcmd_process_chown(struct vsf_session* p_sess){  int the_fd = priv_sock_recv_fd(p_sess->parent_fd);  vsf_privop_do_file_chown(p_sess, the_fd);  vsf_sysutil_close(the_fd);  priv_sock_send_result(p_sess->parent_fd, PRIV_SOCK_RESULT_OK);}static voidcmd_process_get_data_sock(struct vsf_session* p_sess){  int sock_fd = vsf_privop_get_ftp_port_sock(p_sess);  priv_sock_send_result(p_sess->parent_fd, PRIV_SOCK_RESULT_OK);  priv_sock_send_fd(p_sess->parent_fd, sock_fd);  vsf_sysutil_close(sock_fd);}