gbproxy: Track TLLI even when the IMSI is not known

Currently only TLLIs for which it is known that they may be patched
are put into the TLLI list.

This patch changes this to add TLLIs even when the IMSI is not yet
known. A enable_patching flag is added to the gbproxy_tlli_info
structure to control patching.

Note that this puts every active TLLI into the list where accesses
are O(N) currently.

Sponsored-by: On-Waves ehf

2 files changed, 66 insertions, 40 deletions

diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 98b10b972..103ecb59e 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -439,6 +439,9 @@ struct gbproxy_tlli_info *gbprox_find_tlli_by_mi(
 	struct gbproxy_tlli_info *tlli_info;
 	struct gbproxy_patch_state *state = &peer->patch_state;
 
+	if (!is_mi_imsi(mi_data, mi_data_len))
+		return NULL;
+
 	llist_for_each_entry(tlli_info, &state->enabled_tllis, list) {
 		if (tlli_info->mi_data_len != mi_data_len)
 			continue;
@@ -600,6 +603,9 @@ static struct gbproxy_tlli_info *gbprox_get_detached_tlli_info(
 static void gbprox_update_tlli_info(struct gbproxy_tlli_info *tlli_info,
 				    const uint8_t *imsi, size_t imsi_len)
 {
+	if (!is_mi_imsi(imsi, imsi_len))
+		return;
+
 	tlli_info->mi_data_len = imsi_len;
 	tlli_info->mi_data =
 		talloc_realloc_size(tlli_info, tlli_info->mi_data, imsi_len);
@@ -607,26 +613,35 @@ static void gbprox_update_tlli_info(struct gbproxy_tlli_info *tlli_info,
 	memcpy(tlli_info->mi_data, imsi, imsi_len);
 }
 
+void gbprox_reassign_tlli(struct gbproxy_tlli_info *tlli_info,
+			  struct gbproxy_peer *peer, uint32_t new_tlli)
+{
+	if (new_tlli == tlli_info->tlli)
+		return;
+
+	LOGP(DGPRS, LOGL_INFO,
+	     "The TLLI has been reassigned from %08x to %08x\n",
+	     tlli_info->tlli, new_tlli);
+
+	/* TODO: Save old TLLI */
+	tlli_info->tlli = new_tlli;
+}
+
 void gbprox_register_tlli(struct gbproxy_peer *peer, uint32_t tlli,
 				 const uint8_t *imsi, size_t imsi_len)
 {
 	struct gbproxy_patch_state *state = &peer->patch_state;
 	struct gbproxy_tlli_info *tlli_info;
-	int enable_patching;
+	int enable_patching = -1;
 	time_t now = 0;
 	int tlli_already_known;
 
-	if (!imsi || (imsi[0] & GSM_MI_TYPE_MASK) != GSM_MI_TYPE_IMSI)
-		return;
-
-	if (!peer->cfg->check_imsi)
-		return;
-
 	/* Check, whether the IMSI matches */
-	enable_patching = gbprox_check_imsi(peer, imsi, imsi_len);
-
-	if (enable_patching < 0)
-		return;
+	if (is_mi_imsi(imsi, imsi_len)) {
+		enable_patching = gbprox_check_imsi(peer, imsi, imsi_len);
+		if (enable_patching < 0)
+			return;
+	}
 
 	tlli_info = gbprox_find_tlli(peer, tlli);
 
@@ -644,32 +659,23 @@ void gbprox_register_tlli(struct gbproxy_peer *peer, uint32_t tlli,
 
 	tlli_already_known = tlli_info != NULL;
 
-	if (!tlli_already_known && !enable_patching)
-		return;
-
 	tlli_info = gbprox_get_detached_tlli_info(peer, tlli_info, tlli);
 	OSMO_ASSERT(tlli_info != NULL);
 
-	if (enable_patching) {
-		if (!tlli_already_known)
-			LOGP(DGPRS, LOGL_INFO, "Adding TLLI %08x to list\n", tlli);
+	if (!tlli_already_known)
+		LOGP(DGPRS, LOGL_INFO, "Adding TLLI %08x to list\n", tlli);
 
-		now = time(NULL);
+	now = time(NULL);
 
-		gbprox_attach_tlli_info(peer, now, tlli_info);
-		gbprox_update_tlli_info(tlli_info, imsi, imsi_len);
+	gbprox_attach_tlli_info(peer, now, tlli_info);
+	gbprox_update_tlli_info(tlli_info, imsi, imsi_len);
+	if (enable_patching >= 0)
+		tlli_info->enable_patching = enable_patching;
 
-		gbprox_remove_stale_tllis(peer, now);
-		/* Be on the safe side, currently the new tlli_info won't be
-		 * removed, but this not enforced explicitely */
-		tlli_info = NULL;
-	} else {
-		LOGP(DGPRS, LOGL_INFO,
-		     "Removing TLLI %08x from list (patching no longer enabled)\n",
-		     tlli);
-		talloc_free(tlli_info);
-		tlli_info = NULL;
-	}
+	gbprox_remove_stale_tllis(peer, now);
+	/* Be on the safe side, currently the new tlli_info won't be
+	 * removed, but this not enforced explicitely */
+	tlli_info = NULL;
 
 	peer->ctrg->ctr[GBPROX_PEER_CTR_TLLI_CACHE_SIZE].current =
 		state->enabled_tllis_count;
@@ -694,11 +700,17 @@ static void gbprox_unregister_tlli(struct gbproxy_peer *peer, uint32_t tlli)
 
 static int gbprox_check_tlli(struct gbproxy_peer *peer, uint32_t tlli)
 {
+	struct gbproxy_tlli_info *tlli_info;
+
 	LOGP(DGPRS, LOGL_INFO, "Checking TLLI %08x, class: %d\n",
 	     tlli, gprs_tlli_type(tlli));
 
-	return !peer->cfg->check_imsi ||
-		gbprox_find_tlli(peer, tlli) != NULL;
+	if (!peer->cfg->check_imsi)
+		return 1;
+
+	tlli_info = gbprox_find_tlli(peer, tlli);
+
+	return tlli_info != NULL && tlli_info->enable_patching;
 }
 
 /* check whether patching is enabled at this level */
@@ -1240,6 +1252,13 @@ static void gbprox_update_state(struct gbproxy_peer *peer,
 				struct gbproxy_parse_context *parse_ctx)
 {
 	const char *msg_name = "BSSGP";
+	struct gbproxy_tlli_info *tlli_info = NULL;
+
+	if (!peer->cfg->check_imsi)
+		return;
+
+	if (parse_ctx->tlli_enc)
+		tlli_info = gbprox_find_tlli(peer, parse_ctx->tlli);
 
 	if (parse_ctx->llc_msg_name)
 		msg_name = parse_ctx->llc_msg_name;
@@ -1290,7 +1309,8 @@ static void gbprox_update_state(struct gbproxy_peer *peer,
 		     msg_name, mi_buf);
 	}
 
-	if (parse_ctx->new_ptmsi_enc && parse_ctx->to_bss && parse_ctx->imsi) {
+	if (parse_ctx->tlli_enc && parse_ctx->new_ptmsi_enc &&
+	    parse_ctx->to_bss) {
 		/* A new PTMSI has been signaled in the message,
 		 * register new TLLI */
 		uint32_t new_ptmsi;
@@ -1306,9 +1326,11 @@ static void gbprox_update_state(struct gbproxy_peer *peer,
 		LOGP(DGPRS, LOGL_INFO,
 		     "Got new TLLI/PTMSI %08x/%08x (current is %08x)\n",
 		     new_tlli, new_ptmsi, parse_ctx->tlli);
-		gbprox_register_tlli(peer, new_ptmsi,
+		if (tlli_info)
+			gbprox_reassign_tlli(tlli_info, peer, new_tlli);
+		gbprox_register_tlli(peer, new_tlli,
 				     parse_ctx->imsi, parse_ctx->imsi_len);
-	} else if (parse_ctx->tlli && parse_ctx->imsi) {
+	} else if (parse_ctx->tlli_enc && parse_ctx->llc) {
 		gbprox_register_tlli(peer, parse_ctx->tlli,
 				     parse_ctx->imsi, parse_ctx->imsi_len);
 	}
diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index 68d5e74d0..ec73ae646 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -368,10 +368,14 @@ DEFUN(show_gbproxy_tllis, show_gbproxy_tllis_cmd, "show gbproxy tllis",
 
 		llist_for_each_entry(tlli_info, &state->enabled_tllis, list) {
 			time_t age = now - tlli_info->timestamp;
-			snprintf(mi_buf, sizeof(mi_buf), "(invalid)");
-			gsm48_mi_to_string(mi_buf, sizeof(mi_buf),
-					   tlli_info->mi_data,
-					   tlli_info->mi_data_len);
+			if (tlli_info->mi_data_len > 0) {
+				snprintf(mi_buf, sizeof(mi_buf), "(invalid)");
+				gsm48_mi_to_string(mi_buf, sizeof(mi_buf),
+						   tlli_info->mi_data,
+						   tlli_info->mi_data_len);
+			} else {
+				snprintf(mi_buf, sizeof(mi_buf), "(none)");
+			}
 			vty_out(vty, "  TLLI %08x, IMSI %s, AGE %d%s",
 				tlli_info->tlli, mi_buf, (int)age,
 				VTY_NEWLINE);