Fix CVE-2020-12695 (UPnP SUBSCRIBE misbehavior in hostapd WPS AP)

0001-WPS-UPnP-Do-not-allow-event-subscriptions-with-URLs-.patch

@@ -0,0 +1,150 @@
+From 5b78c8f961f25f4dc22d6f2b77ddd06d712cec63 Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <jouni@codeaurora.org>
+Date: Wed, 3 Jun 2020 23:17:35 +0300
+Subject: [PATCH 1/3] WPS UPnP: Do not allow event subscriptions with URLs to
+ other networks
+
+The UPnP Device Architecture 2.0 specification errata ("UDA errata
+16-04-2020.docx") addresses a problem with notifications being allowed
+to go out to other domains by disallowing such cases. Do such filtering
+for the notification callback URLs to avoid undesired connections to
+external networks based on subscriptions that any device in the local
+network could request when WPS support for external registrars is
+enabled (the upnp_iface parameter in hostapd configuration).
+
+Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
+---
+ src/wps/wps_er.c     |  2 +-
+ src/wps/wps_upnp.c   | 38 ++++++++++++++++++++++++++++++++++++--
+ src/wps/wps_upnp_i.h |  3 ++-
+ 3 files changed, 39 insertions(+), 4 deletions(-)
+
+diff --git a/src/wps/wps_er.c b/src/wps/wps_er.c
+index 6bded14327f8..31d2e50e4cff 100644
+--- a/src/wps/wps_er.c
++++ b/src/wps/wps_er.c
+@@ -1298,7 +1298,7 @@ wps_er_init(struct wps_context *wps, const char *ifname, const char *filter)
+ 			   "with %s", filter);
+ 	}
+ 	if (get_netif_info(er->ifname, &er->ip_addr, &er->ip_addr_text,
+-			   er->mac_addr)) {
++			   NULL, er->mac_addr)) {
+ 		wpa_printf(MSG_INFO, "WPS UPnP: Could not get IP/MAC address "
+ 			   "for %s. Does it have IP address?", er->ifname);
+ 		wps_er_deinit(er, NULL, NULL);
+diff --git a/src/wps/wps_upnp.c b/src/wps/wps_upnp.c
+index 6e10e4bc0c3f..7d4b7439940e 100644
+--- a/src/wps/wps_upnp.c
++++ b/src/wps/wps_upnp.c
+@@ -303,6 +303,14 @@ static void subscr_addr_free_all(struct subscription *s)
+ }
+ 
+ 
++static int local_network_addr(struct upnp_wps_device_sm *sm,
++			      struct sockaddr_in *addr)
++{
++	return (addr->sin_addr.s_addr & sm->netmask.s_addr) ==
++		(sm->ip_addr & sm->netmask.s_addr);
++}
++
++
+ /* subscr_addr_add_url -- add address(es) for one url to subscription */
+ static void subscr_addr_add_url(struct subscription *s, const char *url,
+ 				size_t url_len)
+@@ -381,6 +389,7 @@ static void subscr_addr_add_url(struct subscription *s, const char *url,
+ 
+ 	for (rp = result; rp; rp = rp->ai_next) {
+ 		struct subscr_addr *a;
++		struct sockaddr_in *addr = (struct sockaddr_in *) rp->ai_addr;
+ 
+ 		/* Limit no. of address to avoid denial of service attack */
+ 		if (dl_list_len(&s->addr_list) >= MAX_ADDR_PER_SUBSCRIPTION) {
+@@ -389,6 +398,13 @@ static void subscr_addr_add_url(struct subscription *s, const char *url,
+ 			break;
+ 		}
+ 
++		if (!local_network_addr(s->sm, addr)) {
++			wpa_printf(MSG_INFO,
++				   "WPS UPnP: Ignore a delivery URL that points to another network %s",
++				   inet_ntoa(addr->sin_addr));
++			continue;
++		}
++
+ 		a = os_zalloc(sizeof(*a) + alloc_len);
+ 		if (a == NULL)
+ 			break;
+@@ -890,11 +906,12 @@ static int eth_get(const char *device, u8 ea[ETH_ALEN])
+  * @net_if: Selected network interface name
+  * @ip_addr: Buffer for returning IP address in network byte order
+  * @ip_addr_text: Buffer for returning a pointer to allocated IP address text
++ * @netmask: Buffer for returning netmask or %NULL if not needed
+  * @mac: Buffer for returning MAC address
+  * Returns: 0 on success, -1 on failure
+  */
+ int get_netif_info(const char *net_if, unsigned *ip_addr, char **ip_addr_text,
+-		   u8 mac[ETH_ALEN])
++		   struct in_addr *netmask, u8 mac[ETH_ALEN])
+ {
+ 	struct ifreq req;
+ 	int sock = -1;
+@@ -920,6 +937,19 @@ int get_netif_info(const char *net_if, unsigned *ip_addr, char **ip_addr_text,
+ 	in_addr.s_addr = *ip_addr;
+ 	os_snprintf(*ip_addr_text, 16, "%s", inet_ntoa(in_addr));
+ 
++	if (netmask) {
++		os_memset(&req, 0, sizeof(req));
++		os_strlcpy(req.ifr_name, net_if, sizeof(req.ifr_name));
++		if (ioctl(sock, SIOCGIFNETMASK, &req) < 0) {
++			wpa_printf(MSG_ERROR,
++				   "WPS UPnP: SIOCGIFNETMASK failed: %d (%s)",
++				   errno, strerror(errno));
++			goto fail;
++		}
++		addr = (struct sockaddr_in *) &req.ifr_netmask;
++		netmask->s_addr = addr->sin_addr.s_addr;
++	}
++
+ #ifdef __linux__
+ 	os_strlcpy(req.ifr_name, net_if, sizeof(req.ifr_name));
+ 	if (ioctl(sock, SIOCGIFHWADDR, &req) < 0) {
+@@ -1026,11 +1056,15 @@ static int upnp_wps_device_start(struct upnp_wps_device_sm *sm, char *net_if)
+ 
+ 	/* Determine which IP and mac address we're using */
+ 	if (get_netif_info(net_if, &sm->ip_addr, &sm->ip_addr_text,
+-			   sm->mac_addr)) {
++			   &sm->netmask, sm->mac_addr)) {
+ 		wpa_printf(MSG_INFO, "WPS UPnP: Could not get IP/MAC address "
+ 			   "for %s. Does it have IP address?", net_if);
+ 		goto fail;
+ 	}
++	wpa_printf(MSG_DEBUG, "WPS UPnP: Local IP address %s netmask %s hwaddr "
++		   MACSTR,
++		   sm->ip_addr_text, inet_ntoa(sm->netmask),
++		   MAC2STR(sm->mac_addr));
+ 
+ 	/* Listen for incoming TCP connections so that others
+ 	 * can fetch our "xml files" from us.
+diff --git a/src/wps/wps_upnp_i.h b/src/wps/wps_upnp_i.h
+index e87a93232df1..6ead7b4e9a30 100644
+--- a/src/wps/wps_upnp_i.h
++++ b/src/wps/wps_upnp_i.h
+@@ -128,6 +128,7 @@ struct upnp_wps_device_sm {
+ 	u8 mac_addr[ETH_ALEN]; /* mac addr of network i.f. we use */
+ 	char *ip_addr_text; /* IP address of network i.f. we use */
+ 	unsigned ip_addr; /* IP address of network i.f. we use (host order) */
++	struct in_addr netmask;
+ 	int multicast_sd; /* send multicast messages over this socket */
+ 	int ssdp_sd; /* receive discovery UPD packets on socket */
+ 	int ssdp_sd_registered; /* nonzero if we must unregister */
+@@ -158,7 +159,7 @@ struct subscription * subscription_find(struct upnp_wps_device_sm *sm,
+ 					const u8 uuid[UUID_LEN]);
+ void subscr_addr_delete(struct subscr_addr *a);
+ int get_netif_info(const char *net_if, unsigned *ip_addr, char **ip_addr_text,
+-		   u8 mac[ETH_ALEN]);
++		   struct in_addr *netmask, u8 mac[ETH_ALEN]);
+ 
+ /* wps_upnp_ssdp.c */
+ void msearchreply_state_machine_stop(struct advertisement_state_machine *a);
+-- 
+2.20.1
+

0002-WPS-UPnP-Fix-event-message-generation-using-a-long-U.patch

@@ -0,0 +1,59 @@
+From f7d268864a2660b7239b9a8ff5ad37faeeb751ba Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <jouni@codeaurora.org>
+Date: Wed, 3 Jun 2020 22:41:02 +0300
+Subject: [PATCH 2/3] WPS UPnP: Fix event message generation using a long URL
+ path
+
+More than about 700 character URL ended up overflowing the wpabuf used
+for building the event notification and this resulted in the wpabuf
+buffer overflow checks terminating the hostapd process. Fix this by
+allocating the buffer to be large enough to contain the full URL path.
+However, since that around 700 character limit has been the practical
+limit for more than ten years, start explicitly enforcing that as the
+limit or the callback URLs since any longer ones had not worked before
+and there is no need to enable them now either.
+
+Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
+---
+ src/wps/wps_upnp.c       | 9 +++++++--
+ src/wps/wps_upnp_event.c | 3 ++-
+ 2 files changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/src/wps/wps_upnp.c b/src/wps/wps_upnp.c
+index 7d4b7439940e..ab685d52ecab 100644
+--- a/src/wps/wps_upnp.c
++++ b/src/wps/wps_upnp.c
+@@ -328,9 +328,14 @@ static void subscr_addr_add_url(struct subscription *s, const char *url,
+ 	int rerr;
+ 	size_t host_len, path_len;
+ 
+-	/* url MUST begin with http: */
+-	if (url_len < 7 || os_strncasecmp(url, "http://", 7))
++	/* URL MUST begin with HTTP scheme. In addition, limit the length of
++	 * the URL to 700 characters which is around the limit that was
++	 * implicitly enforced for more than 10 years due to a bug in
++	 * generating the event messages. */
++	if (url_len < 7 || os_strncasecmp(url, "http://", 7) || url_len > 700) {
++		wpa_printf(MSG_DEBUG, "WPS UPnP: Reject an unacceptable URL");
+ 		goto fail;
++	}
+ 	url += 7;
+ 	url_len -= 7;
+ 
+diff --git a/src/wps/wps_upnp_event.c b/src/wps/wps_upnp_event.c
+index d7e6edcc6503..08a23612f338 100644
+--- a/src/wps/wps_upnp_event.c
++++ b/src/wps/wps_upnp_event.c
+@@ -147,7 +147,8 @@ static struct wpabuf * event_build_message(struct wps_event_ *e)
+ 	struct wpabuf *buf;
+ 	char *b;
+ 
+-	buf = wpabuf_alloc(1000 + wpabuf_len(e->data));
++	buf = wpabuf_alloc(1000 + os_strlen(e->addr->path) +
++			   wpabuf_len(e->data));
+ 	if (buf == NULL)
+ 		return NULL;
+ 	wpabuf_printf(buf, "NOTIFY %s HTTP/1.1\r\n", e->addr->path);
+-- 
+2.20.1
+

0003-WPS-UPnP-Handle-HTTP-initiation-failures-for-events-.patch

@@ -0,0 +1,47 @@
+From 85aac526af8612c21b3117dadc8ef5944985b476 Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <jouni@codeaurora.org>
+Date: Thu, 4 Jun 2020 21:24:04 +0300
+Subject: [PATCH 3/3] WPS UPnP: Handle HTTP initiation failures for events more
+ properly
+
+While it is appropriate to try to retransmit the event to another
+callback URL on a failure to initiate the HTTP client connection, there
+is no point in trying the exact same operation multiple times in a row.
+Replve the event_retry() calls with event_addr_failure() for these cases
+to avoid busy loops trying to repeat the same failing operation.
+
+These potential busy loops would go through eloop callbacks, so the
+process is not completely stuck on handling them, but unnecessary CPU
+would be used to process the continues retries that will keep failing
+for the same reason.
+
+Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
+---
+ src/wps/wps_upnp_event.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/wps/wps_upnp_event.c b/src/wps/wps_upnp_event.c
+index 08a23612f338..c0d9e41d9a38 100644
+--- a/src/wps/wps_upnp_event.c
++++ b/src/wps/wps_upnp_event.c
+@@ -294,7 +294,7 @@ static int event_send_start(struct subscription *s)
+ 
+ 	buf = event_build_message(e);
+ 	if (buf == NULL) {
+-		event_retry(e, 0);
++		event_addr_failure(e);
+ 		return -1;
+ 	}
+ 
+@@ -302,7 +302,7 @@ static int event_send_start(struct subscription *s)
+ 					 event_http_cb, e);
+ 	if (e->http_event == NULL) {
+ 		wpabuf_free(buf);
+-		event_retry(e, 0);
++		event_addr_failure(e);
+ 		return -1;
+ 	}
+ 
+-- 
+2.20.1
+

hostapd.spec

@@ -2,7 +2,7 @@
 
 Name:           hostapd
 Version:        2.9
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        IEEE 802.11 AP, IEEE 802.1X/WPA/WPA2/EAP/RADIUS Authenticator
 License:        BSD
 URL:            http://w1.fi/hostapd
@@ -16,6 +16,11 @@ Source4:        %{name}.init
 # https://w1.fi/security/2019-7/ap-mode-pmf-disconnection-protection-bypass.txt
 Patch1:         https://w1.fi/security/2019-7/0001-AP-Silently-ignore-management-frame-from-unexpected-.patch
 
+# https://w1.fi/security/2020-1/upnp-subscribe-misbehavior-wps-ap.txt
+Patch2:         https://w1.fi/security/2020-1/0001-WPS-UPnP-Do-not-allow-event-subscriptions-with-URLs-.patch
+Patch3:         https://w1.fi/security/2020-1/0002-WPS-UPnP-Fix-event-message-generation-using-a-long-U.patch
+Patch4:         https://w1.fi/security/2020-1/0003-WPS-UPnP-Handle-HTTP-initiation-failures-for-events-.patch
+
 BuildRequires:  libnl3-devel
 BuildRequires:  openssl-devel
 BuildRequires:  perl-generators
@@ -63,6 +68,10 @@ Logwatch scripts for hostapd.
 
 %patch1 -p1
 
+%patch2 -p1
+%patch3 -p1
+%patch4 -p1
+
 %build
 cd hostapd
 cat defconfig | sed \
@@ -182,6 +191,9 @@ fi
 %{_sysconfdir}/logwatch/scripts/services/%{name}
 
 %changelog
+* Wed Jun 24 2020 Johwn W. Linville <linville@redhat.com> - 2.9-4
+- Fix CVE-2020-12695 (UPnP SUBSCRIBE misbehavior in hostapd WPS AP)
+
 * Wed Jan 29 2020 Fedora Release Engineering <releng@fedoraproject.org> - 2.9-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild