a9874d4959
If no 'script-file = SCRIPTFILE' is specified in the configuration file and if no '-X SCRIPTFILE' or '--script-file SCRIPTFILE' command argument is provided, then this functionality is entirely inactive and no associated subprocess is spawned. Otherwise, ndhc will spawn a subprocess that runs as root that has the sole job of forking off a subprocess that exec's the specified script in a sanitized and fixed-state environment whenever a new DHCPv4 lease is acquired. Note that this script is provided no information about ndhc or the DHCP state in the environment or in any argument fields; it is the responsibility of this script to gather whatever information it needs from either the filesystem or syscalls. This design is intended to avoid the historical problems that are associated with dhcp clients invoking scripts. The path of the scriptfile cannot be changed after ndhc is initially run; ndhc forks off the privsep script subprocess that executes scripts after it has read the configuration file and command arguments, but before it begins processing network data; thus, it is impossible for the network-handling process to modify or influence the script assuming proper OS memory protection. The privsep channel communicates that the script should be run by simply writing a newline; anything else will result in ndhc terminating itself. Before the recommended way to update system state after a change in lease information was to run the fcactus program and watch the associated leasefile for the interface for modification; now no external program is needed for this job.
91 lines
2.7 KiB
C
91 lines
2.7 KiB
C
// Copyright 2014-2020 Nicholas J. Kain <njkain at gmail dot com>
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// SPDX-License-Identifier: MIT
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#ifndef NJK_NDHC_NDHC_H_
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#define NJK_NDHC_NDHC_H_
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#include <stdint.h>
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#include <stdbool.h>
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#include <limits.h>
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#include <net/if.h>
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#include "nk/random.h"
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enum arp_state {
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ARP_QUERY = 0,
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ARP_FOUND,
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ARP_FAILED,
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};
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enum fprint_state {
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FPRINT_NONE = 0,
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FPRINT_INPROGRESS,
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FPRINT_DONE,
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};
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struct client_state_t {
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struct nk_random_state rnd_state;
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long long leaseStartTime, renewTime, rebindTime;
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long long dhcp_wake_ts;
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int ifDeconfig; // Set if the interface has already been deconfigured.
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int listenFd, arpFd, nlFd, rfkillFd;
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int server_arp_sent, router_arp_sent;
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uint32_t nlPortId;
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unsigned int num_dhcp_requests, num_dhcp_renews;
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uint32_t clientAddr, serverAddr, srcAddr, routerAddr;
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uint32_t lease, xid;
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uint8_t routerArp[6], serverArp[6];
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enum arp_state server_arp_state, router_arp_state;
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enum fprint_state fp_state;
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bool using_dhcp_bpf, arp_is_defense, check_fingerprint, program_init,
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sent_renew_or_rebind, carrier_up;
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bool sent_gw_query, sent_first_announce, sent_second_announce;
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};
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struct client_config_t {
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char interface[IFNAMSIZ]; // The name of the interface to use
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char clientid[64]; // Optional client id to use
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char hostname[64]; // Optional hostname to use
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char vendor[64]; // Vendor identification that will be sent
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uint8_t arp[6]; // Our arp address
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uint32_t rfkillIdx; // Index of the corresponding rfkill device
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int metric; // Metric for the default route
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int ifindex; // Index number of the interface to use
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int s6_notify_fd; // File descriptor for s6 notify mechanism
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uint8_t clientid_len; // Length of the clientid
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bool abort_if_no_lease; // Abort if no lease
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bool enable_rfkill; // Listen for rfkill events
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bool enable_s6_notify; // Perform s6 startup notification
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};
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enum {
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SIGNAL_NONE = 0,
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SIGNAL_EXIT,
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SIGNAL_RENEW,
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SIGNAL_RELEASE
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};
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extern struct client_config_t client_config;
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extern int ifchSock[2];
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extern int ifchStream[2];
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extern int sockdSock[2];
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extern int sockdStream[2];
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extern int scriptdSock[2];
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extern int scriptdStream[2];
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extern char state_dir[PATH_MAX];
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extern char chroot_dir[PATH_MAX];
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extern char resolv_conf_d[PATH_MAX];
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extern char script_file[PATH_MAX];
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extern uid_t ndhc_uid;
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extern gid_t ndhc_gid;
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int signals_flagged(void);
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bool carrier_isup(void);
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void set_client_addr(const char *v);
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void show_usage(void);
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void signal_exit(int status);
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int get_clientid_string(const char *str, size_t slen);
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void print_version(void);
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#endif
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