package/minidlna: fix CallStranger a.k.a. CVE-2020-12675

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>

diff --git a/package/minidlna/0002-upnphttp.c-fix-CallStranger-a.k.a.-CVE-2020-12695.patch b/package/minidlna/0002-upnphttp.c-fix-CallStranger-a.k.a.-CVE-2020-12695.patch
new file mode 100644 (file)
index 0000000..7406ce2
--- /dev/null
+++ b/package/minidlna/0002-upnphttp.c-fix-CallStranger-a.k.a.-CVE-2020-12695.patch
@@ -0,0 +1,133 @@
+From 51bfbee51fd0376b5a66c944134af3e9972d8592 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Sun, 6 Sep 2020 11:22:48 +0200
+Subject: [PATCH] upnphttp.c: fix CallStranger a.k.a. CVE-2020-12695
+
+Import CheckCallback function from miniupnpd source code:
+https://github.com/miniupnp/miniupnp/commit/0d9634658860c3c8c209e466cc0ef7002bad3b0a
+
+IPv6 code was kept even if minidlna does not support it currently.
+
+This code is licensed under BSD-3-Clause like minidlna.
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+[Upstream status:
+https://sourceforge.net/p/minidlna/support-requests/71]
+---
+ upnphttp.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++------
+ 1 file changed, 82 insertions(+), 10 deletions(-)
+
+diff --git a/upnphttp.c b/upnphttp.c
+index 974434e..3be793e 100644
+--- a/upnphttp.c
++++ b/upnphttp.c
+@@ -742,6 +742,70 @@ check_event(struct upnphttp *h)
+       return type;
+ }
+ 
++/**
++ * returns 0 if the callback header value is not valid
++ * 1 if it is valid.
++ */
++static int
++checkCallbackURL(struct upnphttp * h)
++{
++      char addrstr[48];
++      int ipv6;
++      const char * p;
++      int i;
++
++      if(!h->req_Callback || h->req_CallbackLen < 8)
++              return 0;
++      if(memcmp(h->req_Callback, "http://", 7) != 0)
++              return 0;
++      ipv6 = 0;
++      i = 0;
++      p = h->req_Callback + 7;
++      if(*p == '[') {
++              p++;
++              ipv6 = 1;
++              while(*p != ']' && i < (sizeof(addrstr)-1)
++                    && p < (h->req_Callback + h->req_CallbackLen))
++                      addrstr[i++] = *(p++);
++      } else {
++              while(*p != '/' && *p != ':' && i < (sizeof(addrstr)-1)
++                    && p < (h->req_Callback + h->req_CallbackLen))
++                      addrstr[i++] = *(p++);
++      }
++      addrstr[i] = '\0';
++      if(ipv6) {
++              struct in6_addr addr;
++              if(inet_pton(AF_INET6, addrstr, &addr) <= 0)
++                      return 0;
++#ifdef ENABLE_IPV6
++              if(!h->ipv6
++                || (0!=memcmp(&addr, &(h->clientaddr_v6), sizeof(struct in6_addr))))
++                      return 0;
++#else
++              return 0;
++#endif
++      } else {
++              struct in_addr addr;
++              if(inet_pton(AF_INET, addrstr, &addr) <= 0)
++                      return 0;
++#ifdef ENABLE_IPV6
++              if(h->ipv6) {
++                      if(!IN6_IS_ADDR_V4MAPPED(&(h->clientaddr_v6)))
++                              return 0;
++                      if(0!=memcmp(&addr, ((const char *)&(h->clientaddr_v6) + 12), 4))
++                              return 0;
++              } else {
++                      if(0!=memcmp(&addr, &(h->clientaddr), sizeof(struct in_addr)))
++                              return 0;
++              }
++#else
++              if(0!=memcmp(&addr, &(h->clientaddr), sizeof(struct in_addr)))
++                      return 0;
++#endif
++      }
++      return 1;
++}
++
+ static void
+ ProcessHTTPSubscribe_upnphttp(struct upnphttp * h, const char * path)
+ {
+@@ -759,17 +823,25 @@ ProcessHTTPSubscribe_upnphttp(struct upnphttp * h, const char * path)
+                * - respond HTTP/x.x 200 OK 
+                * - Send the initial event message */
+               /* Server:, SID:; Timeout: Second-(xx|infinite) */
+-              sid = upnpevents_addSubscriber(path, h->req_Callback,
+-                                             h->req_CallbackLen, h->req_Timeout);
+-              h->respflags = FLAG_TIMEOUT;
+-              if (sid)
+-              {
+-                      DPRINTF(E_DEBUG, L_HTTP, "generated sid=%s\n", sid);
+-                      h->respflags |= FLAG_SID;
+-                      h->req_SID = sid;
+-                      h->req_SIDLen = strlen(sid);
++              /* Check that the callback URL is on the same IP as
++               * the request, and not on the internet, nor on ourself (DOS attack ?) */
++              if(checkCallbackURL(h)) {
++                      sid = upnpevents_addSubscriber(path, h->req_Callback,
++                                                     h->req_CallbackLen, h->req_Timeout);
++                      h->respflags = FLAG_TIMEOUT;
++                      if (sid)
++                      {
++                              DPRINTF(E_DEBUG, L_HTTP, "generated sid=%s\n", sid);
++                              h->respflags |= FLAG_SID;
++                              h->req_SID = sid;
++                              h->req_SIDLen = strlen(sid);
++                      }
++                      BuildResp_upnphttp(h, 0, 0);
++              } else {
++                      DPRINTF(E_WARN, L_HTTP, "Invalid Callback in SUBSCRIBE %.*s",
++                             h->req_CallbackLen, h->req_Callback);
++                      BuildResp2_upnphttp(h, 412, "Precondition Failed", 0, 0);
+               }
+-              BuildResp_upnphttp(h, 0, 0);
+       }
+       else if (type == E_RENEW)
+       {
+-- 
+2.28.0
+