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

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This commit is contained in:
John W. Linville 2020-06-24 13:31:07 -04:00
parent 8c86980eff
commit c583bcd4dd
4 changed files with 269 additions and 1 deletions
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150
0001-WPS-UPnP-Do-not-allow-event-subscriptions-with-URLs-.patch Normal file
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@ -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

59
0002-WPS-UPnP-Fix-event-message-generation-using-a-long-U.patch Normal file
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@ -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

47
0003-WPS-UPnP-Handle-HTTP-initiation-failures-for-events-.patch Normal file
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@ -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

14
hostapd.spec
View File

@ -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