diff options
author | Jasper Orschulko <jasper@fancydomain.eu> | 2023-11-27 01:04:17 +0100 |
---|---|---|
committer | Armin Kuster <akuster808@gmail.com> | 2023-12-17 15:36:42 -0500 |
commit | a1c4d361ed9e5ef72c74bd2849d6f485939bbd4b (patch) | |
tree | 69d5ef07f946131730b1a66ad19a802150483245 | |
parent | a005377cdf1efd4aa6681e73bb663bb1c3ebfd4e (diff) | |
download | meta-openembedded-a1c4d361ed9e5ef72c74bd2849d6f485939bbd4b.tar.gz |
nginx: Mitigate HTTP/2 Stream Resets Flood impact
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 <jasper@fancydomain.eu>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
3 files changed, 95 insertions, 0 deletions
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 @@ | |||
1 | From 2b9667f36551406169e3e2a6a774466ac70a83c0 Mon Sep 17 00:00:00 2001 | ||
2 | From: Maxim Dounin <mdounin@mdounin.ru> | ||
3 | Date: Tue, 10 Oct 2023 15:13:39 +0300 | ||
4 | Subject: [PATCH] HTTP/2: per-iteration stream handling limit. | ||
5 | |||
6 | To ensure that attempts to flood servers with many streams are detected | ||
7 | early, a limit of no more than 2 * max_concurrent_streams new streams per one | ||
8 | event loop iteration was introduced. This limit is applied even if | ||
9 | max_concurrent_streams is not yet reached - for example, if corresponding | ||
10 | streams are handled synchronously or reset. | ||
11 | |||
12 | Further, refused streams are now limited to maximum of max_concurrent_streams | ||
13 | and 100, similarly to priority_limit initial value, providing some tolerance | ||
14 | to clients trying to open several streams at the connection start, yet | ||
15 | low tolerance to flooding attempts. | ||
16 | |||
17 | Upstream-Status: Backport | ||
18 | [https://github.com/nginx/nginx/commit/6ceef192e7af1c507826ac38a2d43f08bf265fb9] | ||
19 | |||
20 | Reduces the impact of HTTP/2 Stream Reset flooding in the nginx product | ||
21 | (CVE-2023-44487). | ||
22 | |||
23 | See: https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ | ||
24 | |||
25 | This patch only reduces the impact and does not completely mitigate the CVE | ||
26 | in question, the latter being due to a design flaw in the HTTP/2 protocol | ||
27 | itself. For transparancy reasons I therefore opted to not mark the | ||
28 | CVE as resolved, so that integrators can decide for themselves, wheither to | ||
29 | enable HTTP/2 support or allow HTTP/1.1 connections only. | ||
30 | |||
31 | Signed-off-by: Jasper Orschulko <jasper@fancydomain.eu> | ||
32 | --- | ||
33 | src/http/v2/ngx_http_v2.c | 15 +++++++++++++++ | ||
34 | src/http/v2/ngx_http_v2.h | 2 ++ | ||
35 | 2 files changed, 17 insertions(+) | ||
36 | |||
37 | diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c | ||
38 | index 3611a2e50..291677aca 100644 | ||
39 | --- a/src/http/v2/ngx_http_v2.c | ||
40 | +++ b/src/http/v2/ngx_http_v2.c | ||
41 | @@ -361,6 +361,7 @@ ngx_http_v2_read_handler(ngx_event_t *rev) | ||
42 | ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http2 read handler"); | ||
43 | |||
44 | h2c->blocked = 1; | ||
45 | + h2c->new_streams = 0; | ||
46 | |||
47 | if (c->close) { | ||
48 | c->close = 0; | ||
49 | @@ -1320,6 +1321,14 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos, | ||
50 | goto rst_stream; | ||
51 | } | ||
52 | |||
53 | + if (h2c->new_streams++ >= 2 * h2scf->concurrent_streams) { | ||
54 | + ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0, | ||
55 | + "client sent too many streams at once"); | ||
56 | + | ||
57 | + status = NGX_HTTP_V2_REFUSED_STREAM; | ||
58 | + goto rst_stream; | ||
59 | + } | ||
60 | + | ||
61 | if (!h2c->settings_ack | ||
62 | && !(h2c->state.flags & NGX_HTTP_V2_END_STREAM_FLAG) | ||
63 | && h2scf->preread_size < NGX_HTTP_V2_DEFAULT_WINDOW) | ||
64 | @@ -1385,6 +1394,12 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos, | ||
65 | |||
66 | rst_stream: | ||
67 | |||
68 | + if (h2c->refused_streams++ > ngx_max(h2scf->concurrent_streams, 100)) { | ||
69 | + ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0, | ||
70 | + "client sent too many refused streams"); | ||
71 | + return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_NO_ERROR); | ||
72 | + } | ||
73 | + | ||
74 | if (ngx_http_v2_send_rst_stream(h2c, h2c->state.sid, status) != NGX_OK) { | ||
75 | return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR); | ||
76 | } | ||
77 | diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h | ||
78 | index 349229711..6a7aaa62c 100644 | ||
79 | --- a/src/http/v2/ngx_http_v2.h | ||
80 | +++ b/src/http/v2/ngx_http_v2.h | ||
81 | @@ -125,6 +125,8 @@ struct ngx_http_v2_connection_s { | ||
82 | ngx_uint_t processing; | ||
83 | ngx_uint_t frames; | ||
84 | ngx_uint_t idle; | ||
85 | + ngx_uint_t new_streams; | ||
86 | + ngx_uint_t refused_streams; | ||
87 | ngx_uint_t priority_limit; | ||
88 | |||
89 | ngx_uint_t pushing; | ||
90 | -- | ||
91 | 2.42.1 | ||
92 | |||
diff --git a/meta-webserver/recipes-httpd/nginx/nginx_1.16.1.bb b/meta-webserver/recipes-httpd/nginx/nginx_1.16.1.bb index 07e9f6ddb..39cfd3a67 100644 --- a/meta-webserver/recipes-httpd/nginx/nginx_1.16.1.bb +++ b/meta-webserver/recipes-httpd/nginx/nginx_1.16.1.bb | |||
@@ -7,4 +7,5 @@ SRC_URI[sha256sum] = "f11c2a6dd1d3515736f0324857957db2de98be862461b5a542a3ac6188 | |||
7 | 7 | ||
8 | SRC_URI += "file://CVE-2019-20372.patch \ | 8 | SRC_URI += "file://CVE-2019-20372.patch \ |
9 | file://CVE-2022-41741-CVE-2022-41742.patch \ | 9 | file://CVE-2022-41741-CVE-2022-41742.patch \ |
10 | file://0001-HTTP-2-per-iteration-stream-handling-limit.patch \ | ||
10 | " | 11 | " |
diff --git a/meta-webserver/recipes-httpd/nginx/nginx_1.17.8.bb b/meta-webserver/recipes-httpd/nginx/nginx_1.17.8.bb index 3d2a5edd2..9fd6d7342 100644 --- a/meta-webserver/recipes-httpd/nginx/nginx_1.17.8.bb +++ b/meta-webserver/recipes-httpd/nginx/nginx_1.17.8.bb | |||
@@ -8,3 +8,5 @@ LIC_FILES_CHKSUM = "file://LICENSE;md5=52e384aaac868b755b93ad5535e2d075" | |||
8 | 8 | ||
9 | SRC_URI[md5sum] = "29cd861a13aae69a058cbabaae86177b" | 9 | SRC_URI[md5sum] = "29cd861a13aae69a058cbabaae86177b" |
10 | SRC_URI[sha256sum] = "97d23ecf6d5150b30e284b40e8a6f7e3bb5be6b601e373a4d013768d5a25965b" | 10 | SRC_URI[sha256sum] = "97d23ecf6d5150b30e284b40e8a6f7e3bb5be6b601e373a4d013768d5a25965b" |
11 | |||
12 | SRC_URI += "file://0001-HTTP-2-per-iteration-stream-handling-limit.patch" | ||