diff options
Diffstat (limited to 'packet_id.c')
| -rw-r--r-- | packet_id.c | 486 |
1 files changed, 0 insertions, 486 deletions
diff --git a/packet_id.c b/packet_id.c deleted file mode 100644 index b11e71f..0000000 --- a/packet_id.c +++ /dev/null @@ -1,486 +0,0 @@ -/* - * OpenVPN -- An application to securely tunnel IP networks - * over a single TCP/UDP port, with support for SSL/TLS-based - * session authentication and key exchange, - * packet encryption, packet authentication, and - * packet compression. - * - * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net> - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 - * as published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program (see the file COPYING included with this - * distribution); if not, write to the Free Software Foundation, Inc., - * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ - -/* - * These routines are designed to catch replay attacks, - * where a man-in-the-middle captures packets and then - * attempts to replay them back later. - * - * We use the "sliding-window" algorithm, similar - * to IPSec. - */ - -#include "syshead.h" - -#ifdef USE_CRYPTO - -#include "packet_id.h" -#include "misc.h" -#include "integer.h" - -#include "memdbg.h" - -/* - * Special time_t value that indicates that - * sequence number has expired. - */ -#define SEQ_UNSEEN ((time_t)0) -#define SEQ_EXPIRED ((time_t)1) - -void -packet_id_init (struct packet_id *p, int seq_backtrack, int time_backtrack) -{ - dmsg (D_PID_DEBUG_LOW, "PID packet_id_init seq_backtrack=%d time_backtrack=%d", - seq_backtrack, - time_backtrack); - - ASSERT (p); - CLEAR (*p); - - if (seq_backtrack) - { - ASSERT (MIN_SEQ_BACKTRACK <= seq_backtrack && seq_backtrack <= MAX_SEQ_BACKTRACK); - ASSERT (MIN_TIME_BACKTRACK <= time_backtrack && time_backtrack <= MAX_TIME_BACKTRACK); - CIRC_LIST_ALLOC (p->rec.seq_list, struct seq_list, seq_backtrack); - p->rec.seq_backtrack = seq_backtrack; - p->rec.time_backtrack = time_backtrack; - } - p->rec.initialized = true; -} - -void -packet_id_free (struct packet_id *p) -{ - if (p) - { - dmsg (D_PID_DEBUG_LOW, "PID packet_id_free"); - if (p->rec.seq_list) - free (p->rec.seq_list); - CLEAR (*p); - } -} - -void -packet_id_add (struct packet_id_rec *p, const struct packet_id_net *pin) -{ - const time_t local_now = now; - if (p->seq_list) - { - packet_id_type diff; - - /* - * If time value increases, start a new - * sequence number sequence. - */ - if (!CIRC_LIST_SIZE (p->seq_list) - || pin->time > p->time - || (pin->id >= (packet_id_type)p->seq_backtrack - && pin->id - (packet_id_type)p->seq_backtrack > p->id)) - { - p->time = pin->time; - p->id = 0; - if (pin->id > (packet_id_type)p->seq_backtrack) - p->id = pin->id - (packet_id_type)p->seq_backtrack; - CIRC_LIST_RESET (p->seq_list); - } - - while (p->id < pin->id) - { - CIRC_LIST_PUSH (p->seq_list, SEQ_UNSEEN); - ++p->id; - } - - diff = p->id - pin->id; - if (diff < (packet_id_type) CIRC_LIST_SIZE (p->seq_list) - && local_now > SEQ_EXPIRED) - CIRC_LIST_ITEM (p->seq_list, diff) = local_now; - } - else - { - p->time = pin->time; - p->id = pin->id; - } -} - -/* - * Expire sequence numbers which can no longer - * be accepted because they would violate - * time_backtrack. - */ -void -packet_id_reap (struct packet_id_rec *p) -{ - const time_t local_now = now; - if (p->time_backtrack) - { - int i; - bool expire = false; - for (i = 0; i < CIRC_LIST_SIZE (p->seq_list); ++i) - { - const time_t t = CIRC_LIST_ITEM (p->seq_list, i); - if (t == SEQ_EXPIRED) - break; - if (!expire && t && t + p->time_backtrack < local_now) - expire = true; - if (expire) - CIRC_LIST_ITEM (p->seq_list, i) = SEQ_EXPIRED; - } - } - p->last_reap = local_now; -} - -/* - * Return true if packet id is ok, or false if - * it is a replay. - */ -bool -packet_id_test (const struct packet_id_rec *p, - const struct packet_id_net *pin) -{ - static int max_backtrack_stat; - packet_id_type diff; - - dmsg (D_PID_DEBUG, - "PID TEST " time_format ":" packet_id_format " " time_format ":" packet_id_format "", - (time_type)p->time, (packet_id_print_type)p->id, (time_type)pin->time, - (packet_id_print_type)pin->id); - - ASSERT (p->initialized); - - if (!pin->id) - return false; - - if (p->seq_backtrack) - { - /* - * In backtrack mode, we allow packet reordering subject - * to the seq_backtrack and time_backtrack constraints. - * - * This mode is used with UDP. - */ - if (pin->time == p->time) - { - /* is packet-id greater than any one we've seen yet? */ - if (pin->id > p->id) - return true; - - /* check packet-id sliding window for original/replay status */ - diff = p->id - pin->id; - - /* keep track of maximum backtrack seen for debugging purposes */ - if ((int)diff > max_backtrack_stat) - { - max_backtrack_stat = (int)diff; - msg (D_BACKTRACK, "Replay-window backtrack occurred [%d]", max_backtrack_stat); - } - - if (diff >= (packet_id_type) CIRC_LIST_SIZE (p->seq_list)) - return false; - - return CIRC_LIST_ITEM (p->seq_list, diff) == 0; - } - else if (pin->time < p->time) /* if time goes back, reject */ - return false; - else /* time moved forward */ - return true; - } - else - { - /* - * In non-backtrack mode, all sequence number series must - * begin at some number n > 0 and must increment linearly without gaps. - * - * This mode is used with TCP. - */ - if (pin->time == p->time) - return !p->id || pin->id == p->id + 1; - else if (pin->time < p->time) /* if time goes back, reject */ - return false; - else /* time moved forward */ - return pin->id == 1; - } -} - -/* - * Read/write a packet ID to/from the buffer. Short form is sequence number - * only. Long form is sequence number and timestamp. - */ - -bool -packet_id_read (struct packet_id_net *pin, struct buffer *buf, bool long_form) -{ - packet_id_type net_id; - net_time_t net_time; - - pin->id = 0; - pin->time = 0; - - if (!buf_read (buf, &net_id, sizeof (net_id))) - return false; - pin->id = ntohpid (net_id); - if (long_form) - { - if (!buf_read (buf, &net_time, sizeof (net_time))) - return false; - pin->time = ntohtime (net_time); - } - return true; -} - -bool -packet_id_write (const struct packet_id_net *pin, struct buffer *buf, bool long_form, bool prepend) -{ - packet_id_type net_id = htonpid (pin->id); - net_time_t net_time = htontime (pin->time); - - if (prepend) - { - if (long_form) - { - if (!buf_write_prepend (buf, &net_time, sizeof (net_time))) - return false; - } - if (!buf_write_prepend (buf, &net_id, sizeof (net_id))) - return false; - } - else - { - if (!buf_write (buf, &net_id, sizeof (net_id))) - return false; - if (long_form) - { - if (!buf_write (buf, &net_time, sizeof (net_time))) - return false; - } - } - return true; -} - -const char * -packet_id_net_print (const struct packet_id_net *pin, bool print_timestamp, struct gc_arena *gc) -{ - struct buffer out = alloc_buf_gc (256, gc); - - buf_printf (&out, "[ #" packet_id_format, (packet_id_print_type)pin->id); - if (print_timestamp && pin->time) - buf_printf (&out, " / time = (" packet_id_format ") %s", - (packet_id_print_type)pin->time, - time_string (pin->time, 0, false, gc)); - - buf_printf (&out, " ]"); - return BSTR (&out); -} - -/* initialize the packet_id_persist structure in a disabled state */ -void -packet_id_persist_init (struct packet_id_persist *p) -{ - p->filename = NULL; - p->fd = -1; - p->time = p->time_last_written = 0; - p->id = p->id_last_written = 0; -} - -/* close the file descriptor if it is open, and switch to disabled state */ -void -packet_id_persist_close (struct packet_id_persist *p) -{ - if (packet_id_persist_enabled (p)) - { - if (close (p->fd)) - msg (D_PID_PERSIST | M_ERRNO, "Close error on --replay-persist file %s", p->filename); - packet_id_persist_init (p); - } -} - -/* load persisted rec packet_id (time and id) only once from file, and set state to enabled */ -void -packet_id_persist_load (struct packet_id_persist *p, const char *filename) -{ - struct gc_arena gc = gc_new (); - if (!packet_id_persist_enabled (p)) - { - /* open packet-id persist file for both read and write */ - p->fd = open (filename, - O_CREAT | O_RDWR | O_BINARY, - S_IRUSR | S_IWUSR); - if (p->fd == -1) - { - msg (D_PID_PERSIST | M_ERRNO, - "Cannot open --replay-persist file %s for read/write", - filename); - } - else - { - struct packet_id_persist_file_image image; - ssize_t n; - -#if defined(HAVE_FLOCK) && defined(LOCK_EX) && defined(LOCK_NB) - if (flock (p->fd, LOCK_EX | LOCK_NB)) - msg (M_ERR, "Cannot obtain exclusive lock on --replay-persist file %s", filename); -#endif - - p->filename = filename; - n = read (p->fd, &image, sizeof(image)); - if (n == sizeof(image)) - { - p->time = p->time_last_written = image.time; - p->id = p->id_last_written = image.id; - dmsg (D_PID_PERSIST_DEBUG, "PID Persist Read from %s: %s", - p->filename, packet_id_persist_print (p, &gc)); - } - else if (n == -1) - { - msg (D_PID_PERSIST | M_ERRNO, - "Read error on --replay-persist file %s", - p->filename); - } - } - } - gc_free (&gc); -} - -/* save persisted rec packet_id (time and id) to file (only if enabled state) */ -void -packet_id_persist_save (struct packet_id_persist *p) -{ - if (packet_id_persist_enabled (p) && p->time && (p->time != p->time_last_written || - p->id != p->id_last_written)) - { - struct packet_id_persist_file_image image; - ssize_t n; - off_t seek_ret; - struct gc_arena gc = gc_new (); - - image.time = p->time; - image.id = p->id; - seek_ret = lseek(p->fd, (off_t)0, SEEK_SET); - if (seek_ret == (off_t)0) - { - n = write(p->fd, &image, sizeof(image)); - if (n == sizeof(image)) - { - p->time_last_written = p->time; - p->id_last_written = p->id; - dmsg (D_PID_PERSIST_DEBUG, "PID Persist Write to %s: %s", - p->filename, packet_id_persist_print (p, &gc)); - } - else - { - msg (D_PID_PERSIST | M_ERRNO, - "Cannot write to --replay-persist file %s", - p->filename); - } - } - else - { - msg (D_PID_PERSIST | M_ERRNO, - "Cannot seek to beginning of --replay-persist file %s", - p->filename); - } - gc_free (&gc); - } -} - -/* transfer packet_id_persist -> packet_id */ -void -packet_id_persist_load_obj (const struct packet_id_persist *p, struct packet_id *pid) -{ - if (p && pid && packet_id_persist_enabled (p) && p->time) - { - pid->rec.time = p->time; - pid->rec.id = p->id; - } -} - -const char * -packet_id_persist_print (const struct packet_id_persist *p, struct gc_arena *gc) -{ - struct buffer out = alloc_buf_gc (256, gc); - - buf_printf (&out, "["); - - if (packet_id_persist_enabled (p)) - { - buf_printf (&out, " #" packet_id_format, (packet_id_print_type)p->id); - if (p->time) - buf_printf (&out, " / time = (" packet_id_format ") %s", - (packet_id_print_type)p->time, - time_string (p->time, 0, false, gc)); - } - - buf_printf (&out, " ]"); - return (char *)out.data; -} - -#ifdef PID_TEST - -void -packet_id_interactive_test () -{ - struct packet_id pid; - struct packet_id_net pin; - bool long_form; - bool count = 0; - bool test; - - const int seq_backtrack = 10; - const int time_backtrack = 10; - - packet_id_init (&pid, seq_backtrack, time_backtrack); - - while (true) { - char buf[80]; - if (!fgets(buf, sizeof(buf), stdin)) - break; - update_time (); - if (sscanf (buf, "%lu,%u", &pin.time, &pin.id) == 2) - { - packet_id_reap_test (&pid.rec); - test = packet_id_test (&pid.rec, &pin); - printf ("packet_id_test (" time_format ", " packet_id_format ") returned %d\n", - (time_type)pin.time, - (packet_id_print_type)pin.id, - test); - if (test) - packet_id_add (&pid.rec, &pin); - } - else - { - long_form = (count < 20); - packet_id_alloc_outgoing (&pid.send, &pin, long_form); - printf ("(" time_format "(" packet_id_format "), %d)\n", - (time_type)pin.time, - (packet_id_print_type)pin.id, - long_form); - if (pid.send.id == 10) - pid.send.id = 0xFFFFFFF8; - ++count; - } - } - packet_id_free (&pid); -} -#endif - -#endif /* USE_CRYPTO */ |