Merge pull request from GHSA-xqhj-fmc7-f8mv

ecdsautils: verify: fix signature verification (CVE-2022-24884)

LICENSE

 The code of Project Gluon may be distributed under the following terms, unless
 noted otherwise in individual files or subtrees.
 
-Copyright (c) 2013-2021, Project Gluon
+Copyright (c) 2013-2022, Project Gluon
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

README.md

@@ -21,7 +21,7 @@ the future development of Gluon.
 
 Please refrain from using the `master` branch for anything else but development purposes!
 Use the most recent release instead. You can list all releases by running `git tag`
-and switch to one by running `git checkout v2021.1.1 && make update`.
+and switch to one by running `git checkout v2021.1.2 && make update`.
 
 If you're using the autoupdater, do not autoupdate nodes with anything but releases.
 If you upgrade using random master commits the nodes *will break* eventually.

docs/conf.py

@@ -20,11 +20,11 @@
 # -- Project information -----------------------------------------------------
 
 project = 'Gluon'
-copyright = '2015-2021, Project Gluon'
+copyright = '2015-2022, Project Gluon'
 author = 'Project Gluon'
 
 # The short X.Y version
-version = '2021.1.1'
+version = '2021.1.2'
 # The full version, including alpha/beta/rc tags
 release = version
 

docs/releases/v2021.1.2.rst

-Gluon 2021.1.2 (unreleased)
-===========================
+Gluon 2021.1.2
+==============
 
 Important notes
 ---------------
 
+This release fixes a **critical security vulnerability** in Gluon's
+autoupdater.
+
 Upgrades to v2021.1 and later releases are only supported from releases v2018.2
 and later. Migration code for upgrades from older versions has been removed to
 simplify maintenance.
@@ -23,11 +26,30 @@ log.
 Bugfixes
 --------
 
-* **[SECURITY]** This release will fix a critical security vulnerability
+* **[SECURITY]** Autoupdater: Fix signature verification
+
+  A recently discovered issue (CVE-2022-24884) in the *ecdsautils* package
+  allows forgery of cryptographic signatures. This vulnerability can be
+  exploited to create a manifest accepted by the autoupdater without knowledge
+  of the signers' private keys. By intercepting nodes' connections to the update
+  server, such a manifest allows to distribute malicious firmware updates.
+
+  This is a **critical** vulnerability. All nodes with autoupdater must be
+  updated. Requiring multiple signatures for an update does *not* mitigate the
+  issue.
+
+  As a temporary workaround, the issue can be mitigated on individual nodes by
+  disabling the autoupdater via config mode or using the following commands::
+
+    uci set autoupdater.settings.enabled=0
+    uci commit autoupdater
+
+  A fixed firmware should be installed manually before enabling the autoupdater
+  again.
 
-  This bugfix has not been pushed to the public Gluon repository yet to avoid
-  disclosing information on the issue. A detailed advisory will be published at
-  the same time as the Gluon release.
+  See security advisory `GHSA-qhcg-9ffp-78pw
+  <https://github.com/freifunk-gluon/ecdsautils/security/advisories/GHSA-qhcg-9ffp-78pw>`_
+  for further information on this vulnerability.
 
 * **[SECURITY]** Config Mode: Prevent Cross-Site Request Forgery (CSRF)
 

docs/site-example/site.conf

--- This is an example site configuration for Gluon v2021.1.1
+-- This is an example site configuration for Gluon v2021.1.2
 --
 -- Take a look at the documentation located at
 -- https://gluon.readthedocs.io/ for details.

docs/user/getting_started.rst

@@ -8,7 +8,7 @@ Gluon's releases are managed using `Git tags`_. If you are just getting
 started with Gluon we recommend to use the latest stable release of Gluon.
 
 Take a look at the `list of gluon releases`_ and notice the latest release,
-e.g. *v2021.1.1*. Always get Gluon using git and don't try to download it
+e.g. *v2021.1.2*. Always get Gluon using git and don't try to download it
 as a Zip archive as the archive will be missing version information.
 
 Please keep in mind that there is no "default Gluon" build; a site configuration
@@ -50,7 +50,7 @@ Building the images
 -------------------
 
 To build Gluon, first check out the repository. Replace *RELEASE* with the
-version you'd like to checkout, e.g. *v2021.1.1*.
+version you'd like to checkout, e.g. *v2021.1.2*.
 
 ::
 

patches/packages/packages/0004-ecdsautils-verify-fix-signature-verification-CVE-2022-24884.patch

+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 27 Apr 2022 19:01:39 +0200
+Subject: ecdsautils: verify: fix signature verification (CVE-2022-24884)
+
+Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
+
+diff --git a/utils/ecdsautils/Makefile b/utils/ecdsautils/Makefile
+index 7f1c76f0301f56b0a88c1f6a1a0147397fde25c7..5ba893be69d40279cd6f5c9e544e941d0011f451 100644
+--- a/utils/ecdsautils/Makefile
++++ b/utils/ecdsautils/Makefile
+@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
+ 
+ PKG_NAME:=ecdsautils
+ PKG_VERSION:=0.3.2.20160630
+-PKG_RELEASE:=1
++PKG_RELEASE:=2
+ PKG_REV:=07538893fb6c2a9539678c45f9dbbf1e4f222b46
+ PKG_MAINTAINER:=Matthias Schiffer <mschiffer@universe-factory.net>
+ PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
+diff --git a/utils/ecdsautils/patches/0001-verify-fix-signature-verification-CVE-2022-24884.patch b/utils/ecdsautils/patches/0001-verify-fix-signature-verification-CVE-2022-24884.patch
+new file mode 100644
+index 0000000000000000000000000000000000000000..34d80cc201c0e87ca654c3def4fbbbddf622b0ba
+--- /dev/null
++++ b/utils/ecdsautils/patches/0001-verify-fix-signature-verification-CVE-2022-24884.patch
+@@ -0,0 +1,48 @@
++From 1d4b091abdf15ad7b2312535b5b95ad70f6dbd08 Mon Sep 17 00:00:00 2001
++Message-Id: <1d4b091abdf15ad7b2312535b5b95ad70f6dbd08.1651078760.git.mschiffer@universe-factory.net>
++From: Matthias Schiffer <mschiffer@universe-factory.net>
++Date: Wed, 20 Apr 2022 22:04:07 +0200
++Subject: [PATCH] verify: fix signature verification (CVE-2022-24884)
++
++Verify that r and s are non-zero. Without these checks, an all-zero
++signature is always considered valid.
++
++While it would be nicer to error out in ecdsa_verify_prepare_legacy()
++already, that would require users of libecdsautil to check a return value
++of the prepare step. To be safe, implement the fix in an API/ABI-compatible
++way that doesn't need changes to the users.
++---
++ src/lib/ecdsa.c | 10 ++++++++++
++ 1 file changed, 10 insertions(+)
++
++diff --git a/src/lib/ecdsa.c b/src/lib/ecdsa.c
++index 8cd7722be8cd..a661b56bd7c8 100644
++--- a/src/lib/ecdsa.c
+++++ b/src/lib/ecdsa.c
++@@ -135,6 +135,12 @@ regenerate:
++ void ecdsa_verify_prepare_legacy(ecdsa_verify_context_t *ctx, const ecc_int256_t *hash, const ecdsa_signature_t *signature) {
++   ecc_int256_t w, u1, tmp;
++ 
+++  if (ecc_25519_gf_is_zero(&signature->s) || ecc_25519_gf_is_zero(&signature->r)) {
+++    // Signature is invalid, mark by setting ctx->r to an invalid value
+++    memset(&ctx->r, 0, sizeof(ctx->r));
+++    return;
+++  }
+++
++   ctx->r = signature->r;
++ 
++   ecc_25519_gf_recip(&w, &signature->s);
++@@ -149,6 +155,10 @@ bool ecdsa_verify_legacy(const ecdsa_verify_context_t *ctx, const ecc_25519_work
++   ecc_25519_work_t s2, work;
++   ecc_int256_t w, tmp;
++ 
+++  // Signature was detected as invalid in prepare step
+++  if (ecc_25519_gf_is_zero(&ctx->r))
+++    return false;
+++
++   ecc_25519_scalarmult(&s2, &ctx->u2, pubkey);
++   ecc_25519_add(&work, &ctx->s1, &s2);
++   ecc_25519_store_xy_legacy(&w, NULL, &work);
++-- 
++2.36.0
++