9ab9118831
No MINIDLNA_IGNORE_CVES entry is added as no CVE has been assigned to minidlna. Indeed, CallStranger vulnerability affect(ed) most of the UPnP stacks (e.g. gupnp, libupnp) Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
134 lines
3.7 KiB
Diff
134 lines
3.7 KiB
Diff
From 51bfbee51fd0376b5a66c944134af3e9972d8592 Mon Sep 17 00:00:00 2001
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From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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Date: Sun, 6 Sep 2020 11:22:48 +0200
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Subject: [PATCH] upnphttp.c: fix CallStranger a.k.a. CVE-2020-12695
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Import CheckCallback function from miniupnpd source code:
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https://github.com/miniupnp/miniupnp/commit/0d9634658860c3c8c209e466cc0ef7002bad3b0a
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IPv6 code was kept even if minidlna does not support it currently.
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This code is licensed under BSD-3-Clause like minidlna.
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Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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[Upstream status:
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https://sourceforge.net/p/minidlna/support-requests/71]
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---
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upnphttp.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++------
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1 file changed, 82 insertions(+), 10 deletions(-)
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diff --git a/upnphttp.c b/upnphttp.c
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index 974434e..3be793e 100644
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--- a/upnphttp.c
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+++ b/upnphttp.c
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@@ -742,6 +742,70 @@ check_event(struct upnphttp *h)
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return type;
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}
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+/**
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+ * returns 0 if the callback header value is not valid
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+ * 1 if it is valid.
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+ */
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+static int
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+checkCallbackURL(struct upnphttp * h)
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+{
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+ char addrstr[48];
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+ int ipv6;
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+ const char * p;
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+ int i;
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+
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+ if(!h->req_Callback || h->req_CallbackLen < 8)
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+ return 0;
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+ if(memcmp(h->req_Callback, "http://", 7) != 0)
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+ return 0;
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+ ipv6 = 0;
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+ i = 0;
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+ p = h->req_Callback + 7;
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+ if(*p == '[') {
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+ p++;
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+ ipv6 = 1;
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+ while(*p != ']' && i < (sizeof(addrstr)-1)
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+ && p < (h->req_Callback + h->req_CallbackLen))
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+ addrstr[i++] = *(p++);
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+ } else {
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+ while(*p != '/' && *p != ':' && i < (sizeof(addrstr)-1)
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+ && p < (h->req_Callback + h->req_CallbackLen))
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+ addrstr[i++] = *(p++);
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+ }
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+ addrstr[i] = '\0';
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+ if(ipv6) {
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+ struct in6_addr addr;
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+ if(inet_pton(AF_INET6, addrstr, &addr) <= 0)
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+ return 0;
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+#ifdef ENABLE_IPV6
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+ if(!h->ipv6
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+ || (0!=memcmp(&addr, &(h->clientaddr_v6), sizeof(struct in6_addr))))
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+ return 0;
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+#else
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+ return 0;
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+#endif
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+ } else {
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+ struct in_addr addr;
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+ if(inet_pton(AF_INET, addrstr, &addr) <= 0)
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+ return 0;
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+#ifdef ENABLE_IPV6
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+ if(h->ipv6) {
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+ if(!IN6_IS_ADDR_V4MAPPED(&(h->clientaddr_v6)))
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+ return 0;
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+ if(0!=memcmp(&addr, ((const char *)&(h->clientaddr_v6) + 12), 4))
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+ return 0;
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+ } else {
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+ if(0!=memcmp(&addr, &(h->clientaddr), sizeof(struct in_addr)))
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+ return 0;
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+ }
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+#else
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+ if(0!=memcmp(&addr, &(h->clientaddr), sizeof(struct in_addr)))
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+ return 0;
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+#endif
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+ }
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+ return 1;
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+}
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+
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static void
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ProcessHTTPSubscribe_upnphttp(struct upnphttp * h, const char * path)
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{
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@@ -759,17 +823,25 @@ ProcessHTTPSubscribe_upnphttp(struct upnphttp * h, const char * path)
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* - respond HTTP/x.x 200 OK
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* - Send the initial event message */
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/* Server:, SID:; Timeout: Second-(xx|infinite) */
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- sid = upnpevents_addSubscriber(path, h->req_Callback,
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- h->req_CallbackLen, h->req_Timeout);
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- h->respflags = FLAG_TIMEOUT;
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- if (sid)
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- {
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- DPRINTF(E_DEBUG, L_HTTP, "generated sid=%s\n", sid);
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- h->respflags |= FLAG_SID;
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- h->req_SID = sid;
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- h->req_SIDLen = strlen(sid);
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+ /* Check that the callback URL is on the same IP as
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+ * the request, and not on the internet, nor on ourself (DOS attack ?) */
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+ if(checkCallbackURL(h)) {
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+ sid = upnpevents_addSubscriber(path, h->req_Callback,
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+ h->req_CallbackLen, h->req_Timeout);
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+ h->respflags = FLAG_TIMEOUT;
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+ if (sid)
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+ {
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+ DPRINTF(E_DEBUG, L_HTTP, "generated sid=%s\n", sid);
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+ h->respflags |= FLAG_SID;
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+ h->req_SID = sid;
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+ h->req_SIDLen = strlen(sid);
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+ }
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+ BuildResp_upnphttp(h, 0, 0);
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+ } else {
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+ DPRINTF(E_WARN, L_HTTP, "Invalid Callback in SUBSCRIBE %.*s",
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+ h->req_CallbackLen, h->req_Callback);
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+ BuildResp2_upnphttp(h, 412, "Precondition Failed", 0, 0);
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}
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- BuildResp_upnphttp(h, 0, 0);
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}
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else if (type == E_RENEW)
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{
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--
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2.28.0
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