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Resolves: RHEL-12728 - nginx:1.22/nginx: HTTP/2: Multiple HTTP/2 enabled web

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servers are vulnerable to a DDoS attack (Rapid Reset Attack)(CVE-2023-44487)
This commit is contained in:
Luboš Uhliarik 2023-10-16 13:32:20 +02:00
parent 53b00116f7
commit 021aed75f8
2 changed files with 82 additions and 1 deletions
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73
nginx-1.22-CVE-2023-44487.patch Normal file
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@ -0,0 +1,73 @@
From b6aa9504cdfb6391d895dcbddc87b9260ea6968c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lubo=C5=A1=20Uhliarik?= <luhliari@redhat.com>
Date: Wed, 11 Oct 2023 09:59:23 +0200
Subject: [PATCH] CVE-2023-44487 - HTTP/2: per-iteration stream handling limit.
To ensure that attempts to flood servers with many streams are detected
early, a limit of no more than 2 * max_concurrent_streams new streams per one
event loop iteration was introduced. This limit is applied even if
max_concurrent_streams is not yet reached - for example, if corresponding
streams are handled synchronously or reset.
Further, refused streams are now limited to maximum of max_concurrent_streams
and 100, similarly to priority_limit initial value, providing some tolerance
to clients trying to open several streams at the connection start, yet
low tolerance to flooding attempts.
---
src/http/v2/ngx_http_v2.c | 15 +++++++++++++++
src/http/v2/ngx_http_v2.h | 2 ++
2 files changed, 17 insertions(+)
diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
index 0e45a7b..253718f 100644
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -361,6 +361,7 @@ ngx_http_v2_read_handler(ngx_event_t *rev)
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http2 read handler");
h2c->blocked = 1;
+ h2c->new_streams = 0;
if (c->close) {
c->close = 0;
@@ -1321,6 +1322,14 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
goto rst_stream;
}
+ if (h2c->new_streams++ >= 2 * h2scf->concurrent_streams) {
+ ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
+ "client sent too many streams at once");
+
+ status = NGX_HTTP_V2_REFUSED_STREAM;
+ goto rst_stream;
+ }
+
if (!h2c->settings_ack
&& !(h2c->state.flags & NGX_HTTP_V2_END_STREAM_FLAG)
&& h2scf->preread_size < NGX_HTTP_V2_DEFAULT_WINDOW)
@@ -1386,6 +1395,12 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
rst_stream:
+ if (h2c->refused_streams++ > ngx_max(h2scf->concurrent_streams, 100)) {
+ ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
+ "client sent too many refused streams");
+ return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_NO_ERROR);
+ }
+
if (ngx_http_v2_send_rst_stream(h2c, h2c->state.sid, status) != NGX_OK) {
return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR);
}
diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h
index 70ee287..7593f1c 100644
--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -124,6 +124,8 @@ struct ngx_http_v2_connection_s {
ngx_uint_t processing;
ngx_uint_t frames;
ngx_uint_t idle;
+ ngx_uint_t new_streams;
+ ngx_uint_t refused_streams;
ngx_uint_t priority_limit;
ngx_uint_t pushing;

10
nginx.spec
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@ -30,7 +30,7 @@
Name: nginx
Epoch: 1
Version: 1.22.1
Release: 1%{?dist}
Release: 2%{?dist}
Summary: A high performance web server and reverse proxy server
Group: System Environment/Daemons
@ -74,6 +74,9 @@ Patch4: nginx-1.20.0-enable-tls1v3-by-default.patch
# https://bugzilla.redhat.com/show_bug.cgi?id=1668717
Patch5: nginx-1.18.0-pkcs11-cert.patch
# https://issues.redhat.com/browse/RHEL-12728
Patch6: nginx-1.22-CVE-2023-44487.patch
%if 0%{?with_gperftools}
BuildRequires: gperftools-devel
%endif
@ -230,6 +233,7 @@ Requires: zlib-devel
%patch3 -p1
%patch4 -p1
%patch5 -p1
%patch6 -p1
cp %{SOURCE200} %{SOURCE210} %{SOURCE10} %{SOURCE12} .
@ -542,6 +546,10 @@ fi
%{nginx_srcdir}/
%changelog
* Mon Oct 16 2023 Luboš Uhliarik <luhliari@redhat.com> - 1:1.22.1-2
- Resolves: RHEL-12728 - nginx:1.22/nginx: HTTP/2: Multiple HTTP/2 enabled web
servers are vulnerable to a DDoS attack (Rapid Reset Attack)(CVE-2023-44487)
* Thu Dec 01 2022 Luboš Uhliarik <luhliari@redhat.com> - 1:1.22.1-1
- Resolves: #2112345 - nginx:1.22 for RHEL 8
- add stream_geoip_module and stream_realip_module