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Bug 1870279 - Transfer via socat fails with openssl enabled
Summary: Transfer via socat fails with openssl enabled
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: socat
Version: CentOS Stream
Hardware: x86_64
OS: Linux
Target Milestone: rc
: 8.0
Assignee: Ondrej Moriš
QA Contact: BaseOS QE Security Team
Depends On:
TreeView+ depends on / blocked
Reported: 2020-08-19 16:08 UTC by Pavel Safronov
Modified: 2021-11-09 20:50 UTC (History)
5 users (show)

Fixed In Version: socat-
Doc Type: No Doc Update
Doc Text:
Clone Of:
Last Closed: 2021-11-09 17:48:19 UTC
Type: Bug
Target Upstream Version:

Attachments (Terms of Use)
don't disable SSL_MODE_AUTO_RETRY (1.40 KB, patch)
2020-08-24 16:36 UTC, Carl George 🤠
no flags Details | Diff

System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker CRYPTO-5247 0 None None None 2021-11-09 18:08:00 UTC
Red Hat Product Errata RHBA-2021:4167 0 None None None 2021-11-09 17:48:26 UTC

Description Pavel Safronov 2020-08-19 16:08:07 UTC
Description of problem:

The receiver side of the transfer with ssl enabled always hits "SSL_read(): Connection reset by peer" when it gets close to EOF and leaves the transfer partially finished.

Version-Release number of selected component (if applicable):

How reproducible:
Almost always. 90% of my attempts failed

Steps to Reproduce:
1. Run the server `socat openssl-listen:12345,reuseaddr,pf=ip6,cert=server.pem - > /dev/null`
2. Run client `yes | head -n 1000000 | socat  -u - openssl-connect:[::1]:12345,cn=host:/example.com,cert=server.pem,cafile=ca.pem` (on the same machine or somewhere else, doesn't matter)
3. You should see an error like this on the receiving side as a result
2020/08/19 08:52:06 socat[2164968] E SSL_read(): Connection reset by peer

Actual results:
Getting an error "E SSL_read(): Connection reset by peer" and transfer fails

Expected results:
No error, transfer succeeds

Additional info:
Allegedly this is the consequence of the modification of file xio-openssl.c introduced in version which forcefully disables SSL_MODE_AUTO_RETRY. After commenting out line "SSL_CTX_clear_mode(*ctx, SSL_MODE_AUTO_RETRY);" and rebuilding the client socat binary I don't have an error anymore.
Also it works well with version of socat.

Comment 1 Pavel Safronov 2020-08-21 17:58:36 UTC
This patch below is fixing the problem by rolling back the change. So basically we don't disable SSL_MODE_AUTO_RETRY anymore.

Tests run results:

For both tests I run the following command multiple times and check the server output
yes | head -n 1000000 | socat  -u - openssl-connect:[::1]:12345,cn=host:/example.com,cert=server.pem,cafile=ca.pem

With patch:
# while true; do socat openssl-listen:12345,reuseaddr,pf=ip6,cert=server.pem - > /dev/null; date; done
Fri Aug 21 10:53:11 PDT 2020
Fri Aug 21 10:53:13 PDT 2020
Fri Aug 21 10:53:15 PDT 2020
Fri Aug 21 10:53:17 PDT 2020
Fri Aug 21 10:53:19 PDT 2020
Fri Aug 21 10:53:22 PDT 2020
Fri Aug 21 10:53:24 PDT 2020

Without patch:
# while true; do ./socat openssl-listen:12345,reuseaddr,pf=ip6,cert=server.pem - > /dev/null; date; done
Fri Aug 21 10:50:01 PDT 2020
2020/08/21 10:50:02 socat[976825] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:02 PDT 2020
2020/08/21 10:50:05 socat[977067] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:05 PDT 2020
2020/08/21 10:50:07 socat[977300] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:07 PDT 2020
2020/08/21 10:50:09 socat[977442] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:09 PDT 2020
2020/08/21 10:50:10 socat[977660] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:10 PDT 2020
2020/08/21 10:50:12 socat[977718] E SSL_read(): Connection reset by peer
Fri Aug 21 10:50:12 PDT 2020
Fri Aug 21 10:50:14 PDT 2020

Here is the patch:

diff -Naur socat- socat-
--- socat-	2019-04-05 13:10:24.000000000 -0700
+++ socat-	2020-08-21 09:59:35.233714747 -0700
@@ -79,9 +79,6 @@
 	RES_AAONLY, RES_PRIMARY are deprecated. You can still enable them with
 	configure option --enable-res-deprecated.
-	New versions of OpenSSL preset SSL_MODE_AUTO_RETRY which may hang socat.
-	Solution: clear SSL_MODE_AUTO_RETRY when it is set.
 	Renamed configure.in to configure.ac and set an appropriate symlink for
 	older environments.
 	Related Gentoo bug 426262: Warning on configure.in
diff -Naur socat- socat-
--- socat-	2019-04-04 01:59:55.000000000 -0700
+++ socat-	2020-08-21 09:58:27.445138134 -0700
@@ -1023,18 +1023,6 @@
-   /* It seems that OpenSSL-1.1.1 presets the mode differently.
-      Without correction socat might hang in SSL_read() */
-   {
-      long mode = 0;
-      mode = SSL_CTX_get_mode(*ctx);
-      if (mode & SSL_MODE_AUTO_RETRY) {
-	 Info("SSL_CTX mode has SSL_MODE_AUTO_RETRY set. Correcting..");
-	 Debug1("SSL_CTX_clean_mode(%p, SSL_MODE_AUTO_RETRY)", *ctx);
-	 SSL_CTX_clear_mode(*ctx, SSL_MODE_AUTO_RETRY);
-      }
-   }
    if (opt_cafile != NULL || opt_capath != NULL) {
       if (sycSSL_CTX_load_verify_locations(*ctx, opt_cafile, opt_capath) != 1) {
 	 int result;

Comment 2 Pavel Safronov 2020-08-21 18:07:20 UTC
Created a pull request to centos8 socat repo with the patch https://git.centos.org/rpms/socat/pull-request/1

Comment 3 Carl George 🤠 2020-08-24 16:36:47 UTC
Created attachment 1712396 [details]
don't disable SSL_MODE_AUTO_RETRY

Here is the patch file from Pavel's pull request.  It is a revert of this upstream commit.


Comment 17 errata-xmlrpc 2021-11-09 17:48:19 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (socat bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


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