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authorJacob Erlbeck <jerlbeck@sysmocom.de>2014-08-11 19:12:24 +0200
committerHolger Hans Peter Freyther <holger@moiji-mobile.com>2014-08-24 16:16:40 +0200
commit0d37671824a50ab0924298284cfd1eb730dbb761 (patch)
treee911fae9a0ac8b1f950d0f211e0020b72e2db833 /openbsc/src/gprs/gb_proxy.c
parent643d5228edd71f50a2ebb27854a4d5f3ff3b2835 (diff)
gbproxy: Use different TLLI/P-TMSI for BSS and SGSN
This patch modifies gbprox_make_bss_ptmsi() to generate a new P-TMSI when patch_ptmsi is set in the configuration instead of using the P-TMSI assigned by the SGSN. It modifies gbprox_make_sgsn_tlli() to either use a foreign TLLI based on the SGSN side P-TMSI or (if there is none) generate a random TLLI if patch_ptmsi is set. Otherwise, the TLLI used by the BSS is used. The seeds for the pseudo-random sequences sre set based on time initially. Note that these are neither cryptographically safe nor protected against collisions. Ticket: OW#1259 Sponsored-by: On-Waves ehf
Diffstat (limited to 'openbsc/src/gprs/gb_proxy.c')
-rw-r--r--openbsc/src/gprs/gb_proxy.c51
1 files changed, 49 insertions, 2 deletions
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 8bad721..86ae0e8 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -446,6 +446,20 @@ struct gbproxy_tlli_info *gbprox_find_tlli(struct gbproxy_peer *peer,
return NULL;
}
+static struct gbproxy_tlli_info *gbprox_find_tlli_by_ptmsi(
+ struct gbproxy_peer *peer,
+ uint32_t ptmsi)
+{
+ struct gbproxy_tlli_info *tlli_info;
+ struct gbproxy_patch_state *state = &peer->patch_state;
+
+ llist_for_each_entry(tlli_info, &state->enabled_tllis, list)
+ if (tlli_info->tlli.ptmsi == ptmsi)
+ return tlli_info;
+
+ return NULL;
+}
+
struct gbproxy_tlli_info *gbprox_find_tlli_by_sgsn_tlli(
struct gbproxy_peer *peer,
uint32_t tlli)
@@ -1605,14 +1619,43 @@ static void gbprox_log_parse_context(struct gbproxy_parse_context *parse_ctx,
static uint32_t gbprox_make_bss_ptmsi(struct gbproxy_peer *peer,
uint32_t sgsn_ptmsi)
{
- return sgsn_ptmsi;
+ uint32_t bss_ptmsi;
+ if (!peer->cfg->patch_ptmsi) {
+ bss_ptmsi = sgsn_ptmsi;
+ } else {
+ do {
+ bss_ptmsi = rand_r(&peer->cfg->bss_ptmsi_state);
+ bss_ptmsi = bss_ptmsi | 0xC0000000;
+
+ if (gbprox_find_tlli_by_ptmsi(peer, bss_ptmsi))
+ bss_ptmsi = GSM_RESERVED_TMSI;
+ } while (bss_ptmsi == GSM_RESERVED_TMSI);
+ }
+
+ return bss_ptmsi;
}
static uint32_t gbprox_make_sgsn_tlli(struct gbproxy_peer *peer,
struct gbproxy_tlli_info *tlli_info,
uint32_t bss_tlli)
{
- return bss_tlli;
+ uint32_t sgsn_tlli;
+ if (!peer->cfg->patch_ptmsi) {
+ sgsn_tlli = bss_tlli;
+ } else if (tlli_info->sgsn_tlli.ptmsi != GSM_RESERVED_TMSI) {
+ sgsn_tlli = gprs_tmsi2tlli(tlli_info->sgsn_tlli.ptmsi,
+ TLLI_FOREIGN);
+ } else {
+ do {
+ /* create random TLLI, 0b01111xxx... */
+ sgsn_tlli = rand_r(&peer->cfg->sgsn_tlli_state);
+ sgsn_tlli = (sgsn_tlli & 0x7fffffff) | 0x78000000;
+
+ if (gbprox_find_tlli_by_sgsn_tlli(peer, sgsn_tlli))
+ sgsn_tlli = 0;
+ } while (!sgsn_tlli);
+ }
+ return sgsn_tlli;
}
static struct gbproxy_tlli_info *gbprox_update_state_ul(
@@ -2698,7 +2741,11 @@ int gbprox_cleanup_peers(struct gbproxy_config *cfg, uint16_t nsei, uint16_t bvc
int gbproxy_init_config(struct gbproxy_config *cfg)
{
+ struct timespec tp;
INIT_LLIST_HEAD(&cfg->bts_peers);
cfg->ctrg = rate_ctr_group_alloc(tall_bsc_ctx, &global_ctrg_desc, 0);
+ clock_gettime(CLOCK_REALTIME, &tp);
+ cfg->bss_ptmsi_state = tp.tv_sec + tp.tv_nsec;
+ cfg->sgsn_tlli_state = tp.tv_sec - tp.tv_nsec;
return 0;
}