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From 3b6431eb9c9dba603385f70a2131ab4a01bf0d3b Mon Sep 17 00:00:00 2001
From: Yann Ylavic <ylavic@apache.org>
Date: Mon, 18 Jan 2021 17:39:12 +0000
Subject: [PATCH] Merge r1885659 from trunk:
mod_auth_digest: Fast validation of the nonce's base64 to fail early if
the format can't match anyway.
Submitted by: ylavic
Reviewed by: ylavic, covener, jailletc36
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1885666 13f79535-47bb-0310-9956-ffa450edef68
Upstream-Status: Backport
CVE: CVE-2020-35452
Reference to upstream patch:
https://security-tracker.debian.org/tracker/CVE-2020-35452
https://github.com/apache/httpd/commit/3b6431eb9c9dba603385f70a2131ab4a01bf0d3b
Signed-off-by: Li Wang <li.wang@windriver.com>
---
modules/aaa/mod_auth_digest.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/modules/aaa/mod_auth_digest.c b/modules/aaa/mod_auth_digest.c
index b760941..0825b1b 100644
--- a/modules/aaa/mod_auth_digest.c
+++ b/modules/aaa/mod_auth_digest.c
@@ -1422,9 +1422,14 @@ static int check_nonce(request_rec *r, digest_header_rec *resp,
time_rec nonce_time;
char tmp, hash[NONCE_HASH_LEN+1];
- if (strlen(resp->nonce) != NONCE_LEN) {
+ /* Since the time part of the nonce is a base64 encoding of an
+ * apr_time_t (8 bytes), it should end with a '=', fail early otherwise.
+ */
+ if (strlen(resp->nonce) != NONCE_LEN
+ || resp->nonce[NONCE_TIME_LEN - 1] != '=') {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01775)
- "invalid nonce %s received - length is not %d",
+ "invalid nonce '%s' received - length is not %d "
+ "or time encoding is incorrect",
resp->nonce, NONCE_LEN);
note_digest_auth_failure(r, conf, resp, 1);
return HTTP_UNAUTHORIZED;
--
2.7.4
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