[M] Change in osmo-upf[master]: Validate session remote CP F-SEID and use it to transmit session requ...

21 Nov 2025

pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-upf/+/41482?usp=email )
Change subject: Validate session remote CP F-SEID and use it to transmit session requests
......................................................................
Validate session remote CP F-SEID and use it to transmit session requests
Change-Id: Ifccd4d2b8d500c9928778400bb096baaa12c9a31
---
M include/osmocom/upf/pfcp_entity_peer.h
M src/osmo-upf/pfcp_entity_peer.c
M src/osmo-upf/up_endpoint.c
M src/osmo-upf/up_session.c
4 files changed, 155 insertions(+), 34 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-upf refs/changes/82/41482/1

diff --git a/include/osmocom/upf/pfcp_entity_peer.h b/include/osmocom/upf/pfcp_entity_peer.h
index d2727e5..ae771eb 100644
--- a/include/osmocom/upf/pfcp_entity_peer.h
+++ b/include/osmocom/upf/pfcp_entity_peer.h
@@ -73,9 +73,12 @@
char *pfcp_entity_peer_remote_addr_str(struct pfcp_entity_peer *entity_peer);
-struct osmo_pfcp_msg *pfcp_entity_peer_init_tx(struct pfcp_entity_peer *entity_peer,
-					       struct osmo_pfcp_msg *in_reply_to,
-					       enum osmo_pfcp_message_type message_type);
+struct osmo_pfcp_msg *pfcp_entity_peer_init_tx_req(struct pfcp_entity_peer *peer,
+						   const struct osmo_sockaddr *dst_addr,
+						   enum osmo_pfcp_message_type message_type);
+struct osmo_pfcp_msg *pfcp_entity_peer_init_tx_resp(struct pfcp_entity_peer *peer,
+						    struct osmo_pfcp_msg *in_reply_to,
+						    enum osmo_pfcp_message_type message_type);
struct up_session *pfcp_entity_peer_find_up_session_by_up_seid(struct pfcp_entity_peer *entity_peer, uint64_t up_seid);
 struct up_session *pfcp_entity_peer_find_up_session_by_cp_f_seid(struct pfcp_entity_peer *entity_peer, const struct osmo_pfcp_ie_f_seid *cp_f_seid);
diff --git a/src/osmo-upf/pfcp_entity_peer.c b/src/osmo-upf/pfcp_entity_peer.c
index db02f78..7b8c28d 100644
--- a/src/osmo-upf/pfcp_entity_peer.c
+++ b/src/osmo-upf/pfcp_entity_peer.c
@@ -194,15 +194,22 @@
    m->ctx.peer_use_token = NULL;
 }
-struct osmo_pfcp_msg *pfcp_entity_peer_init_tx(struct pfcp_entity_peer *peer,
-					       struct osmo_pfcp_msg *in_reply_to,
-					       enum osmo_pfcp_message_type message_type)
+struct osmo_pfcp_msg *pfcp_entity_peer_init_tx_req(struct pfcp_entity_peer *peer,
+						   const struct osmo_sockaddr *dst_addr,
+						   enum osmo_pfcp_message_type message_type)
 {
    struct osmo_pfcp_msg *tx;
-	if (in_reply_to)
-		tx = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, in_reply_to, message_type);
-	else
-		tx = osmo_pfcp_msg_alloc_tx_req(OTC_SELECT, &peer->remote_addr, message_type);
+	tx = osmo_pfcp_msg_alloc_tx_req(OTC_SELECT, dst_addr, message_type);
+	pfcp_entity_peer_set_msg_ctx(peer, tx);
+	return tx;
+}
+
+struct osmo_pfcp_msg *pfcp_entity_peer_init_tx_resp(struct pfcp_entity_peer *peer,
+						    struct osmo_pfcp_msg *in_reply_to,
+						    enum osmo_pfcp_message_type message_type)
+{
+	struct osmo_pfcp_msg *tx;
+	tx = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, in_reply_to, message_type);
    pfcp_entity_peer_set_msg_ctx(peer, tx);
    return tx;
 }
@@ -211,7 +218,7 @@
 {
    struct osmo_pfcp_msg *resp;
-	resp = pfcp_entity_peer_init_tx(entity_peer, m, OSMO_PFCP_MSGT_ASSOC_SETUP_RESP);
+	resp = pfcp_entity_peer_init_tx_resp(entity_peer, m, OSMO_PFCP_MSGT_ASSOC_SETUP_RESP);
resp->ies.assoc_setup_resp = (struct osmo_pfcp_msg_assoc_setup_resp) {
    	.cause = cause,
@@ -232,7 +239,7 @@
 {
    struct osmo_pfcp_msg *resp;
-	resp = pfcp_entity_peer_init_tx(peer, m, OSMO_PFCP_MSGT_ASSOC_RELEASE_RESP);
+	resp = pfcp_entity_peer_init_tx_resp(peer, m, OSMO_PFCP_MSGT_ASSOC_RELEASE_RESP);
resp->ies.assoc_release_resp = (struct osmo_pfcp_msg_assoc_release_resp) {
    	.cause = cause,
@@ -307,7 +314,9 @@
 {
    enum osmo_pfcp_cause cause = OSMO_PFCP_CAUSE_REQUEST_ACCEPTED;
    struct osmo_pfcp_msg *resp;
-	struct up_session *session = pfcp_entity_peer_find_up_session_by_cp_f_seid(peer, &m->ies.session_est_req.cp_f_seid);
+	struct up_session *session;
+
+	session = pfcp_entity_peer_find_up_session_by_cp_f_seid(peer, &m->ies.session_est_req.cp_f_seid);
    if (!session)
    	session = up_session_alloc(peer, &m->ies.session_est_req.cp_f_seid);
    if (!session) {
@@ -324,7 +333,7 @@
    return;
nack_response:
-	resp = pfcp_entity_peer_init_tx(peer, m, OSMO_PFCP_MSGT_SESSION_EST_RESP);
+	resp = pfcp_entity_peer_init_tx_resp(peer, m, OSMO_PFCP_MSGT_SESSION_EST_RESP);
    resp->h.seid = m->ies.session_est_req.cp_f_seid.seid;
    resp->h.seid_present = true;
    resp->ies.session_est_resp = (struct osmo_pfcp_msg_session_est_resp){
diff --git a/src/osmo-upf/up_endpoint.c b/src/osmo-upf/up_endpoint.c
index f53dc50..8161042 100644
--- a/src/osmo-upf/up_endpoint.c
+++ b/src/osmo-upf/up_endpoint.c
@@ -166,61 +166,137 @@
    		      OSMO_PFCP_CAUSE_SERVICE_NOT_SUPPORTED);
 }
+/* Validate received F-SEID IP address */
+static enum osmo_pfcp_cause up_ep_validate_cp_f_seid_addr(const struct up_endpoint *up_ep,
+							  const struct osmo_pfcp_ie_f_seid *f_seid)
+{
+	const struct osmo_sockaddr *local_addr;
+
+	OSMO_ASSERT(up_ep);
+	OSMO_ASSERT(f_seid)
+
+	/* Validate the F-SEID contains an IP address we can send requests to later on: */
+	local_addr = osmo_pfcp_endpoint_get_local_addr(up_ep->pfcp_ep);
+	OSMO_ASSERT(local_addr);
+	switch (local_addr->u.sa.sa_family) {
+	case AF_INET:
+		if (!f_seid->ip_addr.v4_present)
+			return OSMO_PFCP_CAUSE_MANDATORY_IE_INCORRECT;
+		break;
+	case AF_INET6:
+		if (!f_seid->ip_addr.v4_present &&
+		    !f_seid->ip_addr.v6_present)
+			return OSMO_PFCP_CAUSE_MANDATORY_IE_INCORRECT;
+		break;
+	default:
+		OSMO_ASSERT(0);
+	}
+	return OSMO_PFCP_CAUSE_REQUEST_ACCEPTED;
+}
+
 static void up_ep_rx_session_est_req(struct up_endpoint *up_ep, const struct osmo_pfcp_msg *m)
 {
-	if (!m->ctx.peer_fi) {
-		struct osmo_pfcp_msg *tx;
-		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Peer is not associated, cannot establish session\n");
-		tx = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_EST_RESP);
-		tx->ies.session_est_resp.cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
-		osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, tx);
-		return;
+	struct osmo_pfcp_msg *resp;
+	enum osmo_pfcp_cause cause;
+
+	cause = up_ep_validate_cp_f_seid_addr(up_ep, &m->ies.session_est_req.cp_f_seid);
+	if (cause != OSMO_PFCP_CAUSE_REQUEST_ACCEPTED) {
+		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Remote CP F-SEID IP address invalid\n");
+		goto nack_response;
    }
+
+	if (!m->ctx.peer_fi) {
+		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Peer is not associated, cannot establish session\n");
+		cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
+		goto nack_response;
+	}
+
    osmo_fsm_inst_dispatch(m->ctx.peer_fi, PFCP_ENTITY_PEER_EV_RX_SESSION_EST_REQ, (void *)m);
+	return;
+
+nack_response:
+	resp = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_EST_RESP);
+	resp->ies.session_est_resp.cause = cause;
+	osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, resp);
 }
static void up_ep_rx_session_mod_req(struct up_endpoint *up_ep, const struct osmo_pfcp_msg *m)
 {
+	struct osmo_pfcp_msg *resp;
+	enum osmo_pfcp_cause cause;
+
+	if (m->ies.session_mod_req.cp_f_seid_present) {
+		cause = up_ep_validate_cp_f_seid_addr(up_ep, &m->ies.session_mod_req.cp_f_seid);
+		if (cause != OSMO_PFCP_CAUSE_REQUEST_ACCEPTED) {
+			OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Remote CP F-SEID IP address invalid\n");
+			goto nack_response;
+		}
+	}
+
    if (!m->ctx.session_fi) {
    	/* Session not found. */
-		struct osmo_pfcp_msg *tx;
-		tx = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_MOD_RESP);
    	if (!m->ctx.peer_fi) {
    		/* Not even the peer is associated. */
    		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Peer is not associated, cannot modify session\n");
-			tx->ies.session_mod_resp.cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
+			cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
+			goto nack_response;
    	} else {
    		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR,
    				  "No established session with SEID=0x%"PRIx64", cannot modify\n",
    				  m->h.seid);
-			tx->ies.session_mod_resp.cause = OSMO_PFCP_CAUSE_SESSION_CTX_NOT_FOUND;
+			cause = OSMO_PFCP_CAUSE_SESSION_CTX_NOT_FOUND;
+			goto nack_response;
    	}
-		osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, tx);
-		return;
    }
+
    osmo_fsm_inst_dispatch(m->ctx.session_fi, UP_SESSION_EV_RX_SESSION_MOD_REQ, (void *)m);
+	return;
+
+nack_response:
+	resp = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_MOD_RESP);
+	resp->ies.session_mod_resp.cause = cause;
+	osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, resp);
 }
static void up_ep_rx_session_del_req(struct up_endpoint *up_ep, const struct osmo_pfcp_msg *m)
 {
+	struct osmo_pfcp_msg *resp;
+	enum osmo_pfcp_cause cause;
+
+#if 0
+	/* Can be enabled once libosmo-pfcp struct osmo_pfcp_msg_session_del_req supports the IE: */
+	if (m->ies.session_del_req.cp_f_seid_present) {
+		cause = up_ep_validate_cp_f_seid_addr(up_ep, &m->ies.session_mod_req.cp_f_seid);
+		if (cause != OSMO_PFCP_CAUSE_REQUEST_ACCEPTED) {
+			OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Remote CP F-SEID IP address invalid\n");
+			goto nack_response;
+		}
+	}
+#endif
+
    if (!m->ctx.session_fi) {
    	/* Session not found. */
-		struct osmo_pfcp_msg *tx;
-		tx = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_DEL_RESP);
    	if (!m->ctx.peer_fi) {
    		/* Not even the peer is associated. */
    		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR, "Peer is not associated, cannot delete session\n");
-			tx->ies.session_del_resp.cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
+			cause = OSMO_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOC;
+			goto nack_response;
    	} else {
    		OSMO_LOG_PFCP_MSG(m, LOGL_ERROR,
    				  "No established session with SEID=0x%"PRIx64", cannot delete\n",
    				  m->h.seid);
-			tx->ies.session_del_resp.cause = OSMO_PFCP_CAUSE_SESSION_CTX_NOT_FOUND;
+			cause = OSMO_PFCP_CAUSE_SESSION_CTX_NOT_FOUND;
+			goto nack_response;
    	}
-		osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, tx);
-		return;
    }
+
    osmo_fsm_inst_dispatch(m->ctx.session_fi, UP_SESSION_EV_RX_SESSION_DEL_REQ, (void *)m);
+	return;
+
+nack_response:
+	resp = osmo_pfcp_msg_alloc_tx_resp(OTC_SELECT, m, OSMO_PFCP_MSGT_SESSION_DEL_RESP);
+	resp->ies.session_del_resp.cause = cause;
+	osmo_pfcp_endpoint_tx(up_ep->pfcp_ep, resp);
 }
static void up_ep_rx_session_rep_req(struct up_endpoint *up_ep, const struct osmo_pfcp_msg *m)
diff --git a/src/osmo-upf/up_session.c b/src/osmo-upf/up_session.c
index 5f406d5..9693745 100644
--- a/src/osmo-upf/up_session.c
+++ b/src/osmo-upf/up_session.c
@@ -90,10 +90,43 @@
    return 1;
 }
+/* Return as dst IP address the IP address from remote's CP F-SEID that matches
+ * our local endpoint configuration.
+ * Asserts regarding cp_f_seid are validated during session establishment/modification/deletion,
+ * see pfcp_entityt_peer_validate_cp_f_seid(). */
+static const struct osmo_sockaddr *up_session_req_dst_addr(const struct up_session *session)
+{
+	const struct osmo_sockaddr *src_addr = osmo_pfcp_endpoint_get_local_addr(session->entity_peer->node_peer->up_endpoint->pfcp_ep);
+	switch (src_addr->u.sa.sa_family) {
+	case AF_INET:
+		OSMO_ASSERT(session->cp_f_seid.ip_addr.v4_present);
+		return &session->cp_f_seid.ip_addr.v4;
+	case AF_INET6:
+		if (session->cp_f_seid.ip_addr.v6_present)
+			return &session->cp_f_seid.ip_addr.v6;
+		if (session->cp_f_seid.ip_addr.v4_present)
+			return &session->cp_f_seid.ip_addr.v4;
+		OSMO_ASSERT(0);
+		break;
+	default:
+		OSMO_ASSERT(0);
+		break;
+	}
+	return NULL;
+}
+
 struct osmo_pfcp_msg *up_session_init_tx(struct up_session *session, struct osmo_pfcp_msg *in_reply_to,
    				 enum osmo_pfcp_message_type message_type)
 {
-	struct osmo_pfcp_msg *tx = pfcp_entity_peer_init_tx(session->entity_peer, in_reply_to, message_type);
+	struct osmo_pfcp_msg *tx;
+	if (in_reply_to) {
+		/* Use req src IP address as resp dst IP address: */
+		tx = pfcp_entity_peer_init_tx_resp(session->entity_peer, in_reply_to, message_type);
+	} else {
+		const struct osmo_sockaddr *dst_addr = up_session_req_dst_addr(session);
+		/* Use IP address from remote's CP F-SEID as dst IP address: */
+		tx = pfcp_entity_peer_init_tx_req(session->entity_peer, dst_addr, message_type);
+	}
    tx->h.seid = session->cp_f_seid.seid;
    tx->h.seid_present = true;
    up_session_set_msg_ctx(session, tx);
-- 
To view, visit https://gerrit.osmocom.org/c/osmo-upf/+/41482?usp=email
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Gerrit-MessageType: newchange
Gerrit-Project: osmo-upf
Gerrit-Branch: master
Gerrit-Change-Id: Ifccd4d2b8d500c9928778400bb096baaa12c9a31
Gerrit-Change-Number: 41482
Gerrit-PatchSet: 1
Gerrit-Owner: pespin pespin@sysmocom.de



    

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[M] Change in osmo-upf[master]: Validate session remote CP F-SEID and use it to transmit session requ...