From: Jasper Orschulko <jas...@fancydomain.eu> Reduces the impact of HTTP/2 Stream Reset flooding in the nginx product (CVE-2023-44487).
See: https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ This patch only reduces the impact and does not completely mitigate the CVE in question, the latter being due to a design flaw in the HTTP/2 protocol itself. For transparancy reasons I therefore opted to not mark the CVE as resolved, so that integrators can decide for themselves, wheither to enable HTTP/2 support or allow HTTP/1.1 connections only. Signed-off-by: Jasper Orschulko <jas...@fancydomain.eu> --- ...-per-iteration-stream-handling-limit.patch | 92 +++++++++++++++++++ .../recipes-httpd/nginx/nginx_1.20.1.bb | 1 + .../recipes-httpd/nginx/nginx_1.21.1.bb | 2 + 3 files changed, 95 insertions(+) create mode 100644 meta-webserver/recipes-httpd/nginx/files/0001-HTTP-2-per-iteration-stream-handling-limit.patch diff --git a/meta-webserver/recipes-httpd/nginx/files/0001-HTTP-2-per-iteration-stream-handling-limit.patch b/meta-webserver/recipes-httpd/nginx/files/0001-HTTP-2-per-iteration-stream-handling-limit.patch new file mode 100644 index 000000000..7dd1e721c --- /dev/null +++ b/meta-webserver/recipes-httpd/nginx/files/0001-HTTP-2-per-iteration-stream-handling-limit.patch @@ -0,0 +1,92 @@ +From 2b9667f36551406169e3e2a6a774466ac70a83c0 Mon Sep 17 00:00:00 2001 +From: Maxim Dounin <mdou...@mdounin.ru> +Date: Tue, 10 Oct 2023 15:13:39 +0300 +Subject: [PATCH] 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. + +Upstream-Status: Backport +[https://github.com/nginx/nginx/commit/6ceef192e7af1c507826ac38a2d43f08bf265fb9] + +Reduces the impact of HTTP/2 Stream Reset flooding in the nginx product +(CVE-2023-44487). + +See: https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ + +This patch only reduces the impact and does not completely mitigate the CVE +in question, the latter being due to a design flaw in the HTTP/2 protocol +itself. For transparancy reasons I therefore opted to not mark the +CVE as resolved, so that integrators can decide for themselves, wheither to +enable HTTP/2 support or allow HTTP/1.1 connections only. + +Signed-off-by: Jasper Orschulko <jas...@fancydomain.eu> +--- + 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 3611a2e50..291677aca 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; +@@ -1320,6 +1321,14 @@ 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) +@@ -1385,6 +1394,12 @@ 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 349229711..6a7aaa62c 100644 +--- a/src/http/v2/ngx_http_v2.h ++++ b/src/http/v2/ngx_http_v2.h +@@ -125,6 +125,8 @@ 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; +-- +2.42.1 + diff --git a/meta-webserver/recipes-httpd/nginx/nginx_1.20.1.bb b/meta-webserver/recipes-httpd/nginx/nginx_1.20.1.bb index 09a1b4559..8bed04d6d 100644 --- a/meta-webserver/recipes-httpd/nginx/nginx_1.20.1.bb +++ b/meta-webserver/recipes-httpd/nginx/nginx_1.20.1.bb @@ -2,6 +2,7 @@ require nginx.inc SRC_URI += "file://CVE-2021-3618.patch \ file://CVE-2022-41741-CVE-2022-41742.patch \ + file://0001-HTTP-2-per-iteration-stream-handling-limit.patch \ " LIC_FILES_CHKSUM = "file://LICENSE;md5=206629dc7c7b3e87acb31162363ae505" diff --git a/meta-webserver/recipes-httpd/nginx/nginx_1.21.1.bb b/meta-webserver/recipes-httpd/nginx/nginx_1.21.1.bb index b69fd7dab..73b5c93c9 100644 --- a/meta-webserver/recipes-httpd/nginx/nginx_1.21.1.bb +++ b/meta-webserver/recipes-httpd/nginx/nginx_1.21.1.bb @@ -1,5 +1,7 @@ require nginx.inc +SRC_URI += "file://0001-HTTP-2-per-iteration-stream-handling-limit.patch" + # 1.20.x branch is the current stable branch, the recommended default # 1.21.x is the current mainline branches containing all new features DEFAULT_PREFERENCE = "-1" -- 2.42.1
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