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Relax GSS Kex restriction in FIPS mode

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Resolves: RHEL-91181
This commit is contained in:
Dmitry Belyavskiy 2025-08-04 15:19:35 +02:00
parent 2303b82ca8
commit 79ecdd9f8c
2 changed files with 39 additions and 68 deletions
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101
openssh-7.7p1-fips.patch
View File

@ -268,9 +268,24 @@ diff -up openssh-8.6p1/ssh.c.fips openssh-8.6p1/ssh.c
/* Expand SecurityKeyProvider if it refers to an environment variable */
if (options.sk_provider != NULL && *options.sk_provider == '$' &&
strlen(options.sk_provider) > 1) {
diff -up openssh-8.6p1/sshconnect2.c.fips openssh-8.6p1/sshconnect2.c
--- openssh-8.6p1/sshconnect2.c.fips 2021-05-06 12:08:36.485926777 +0200
+++ openssh-8.6p1/sshconnect2.c 2021-05-06 12:08:36.501926900 +0200
diff -up openssh-9.9p1/ssh-gss.h.xxx openssh-9.9p1/ssh-gss.h
--- openssh-9.9p1/ssh-gss.h.xxx 2025-08-04 15:02:15.895341244 +0200
+++ openssh-9.9p1/ssh-gss.h 2025-08-04 15:02:54.826304548 +0200
@@ -94,6 +94,11 @@ extern char **k5users_allowed_cmds;
KEX_GSS_GRP14_SHA1_ID "," \
KEX_GSS_GEX_SHA1_ID
+#define GSS_KEX_DEFAULT_KEX_FIPS \
+ KEX_GSS_GRP14_SHA256_ID "," \
+ KEX_GSS_GRP16_SHA512_ID "," \
+ KEX_GSS_NISTP256_SHA256_ID
+
#include "digest.h" /* SSH_DIGEST_MAX_LENGTH */
typedef struct {
diff -up openssh-9.9p1/sshconnect2.c.xxx openssh-9.9p1/sshconnect2.c
--- openssh-9.9p1/sshconnect2.c.xxx 2025-08-04 14:58:08.908229826 +0200
+++ openssh-9.9p1/sshconnect2.c 2025-08-04 15:07:59.942477440 +0200
@@ -45,6 +45,8 @@
#include <vis.h>
#endif
@ -280,75 +295,27 @@ diff -up openssh-8.6p1/sshconnect2.c.fips openssh-8.6p1/sshconnect2.c
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
@@ -269,36 +271,41 @@ ssh_kex2(struct ssh *ssh, char *host, st
@@ -274,6 +277,9 @@ ssh_kex2(struct ssh *ssh, char *host, st
#if defined(GSSAPI) && defined(WITH_OPENSSL)
if (options.gss_keyex) {
- /* Add the GSSAPI mechanisms currently supported on this
- * client to the key exchange algorithm proposal */
- orig = myproposal[PROPOSAL_KEX_ALGS];
-
- if (options.gss_server_identity) {
- gss_host = xstrdup(options.gss_server_identity);
- } else if (options.gss_trust_dns) {
- gss_host = remote_hostname(ssh);
- /* Fall back to specified host if we are using proxy command
- * and can not use DNS on that socket */
- if (strcmp(gss_host, "UNKNOWN") == 0) {
- free(gss_host);
+ if (FIPS_mode()) {
+ logit("Disabling GSSAPIKeyExchange. Not usable in FIPS mode");
+ options.gss_keyex = 0;
+ } else {
+ /* Add the GSSAPI mechanisms currently supported on this
+ * client to the key exchange algorithm proposal */
+ orig = myproposal[PROPOSAL_KEX_ALGS];
+ char * gss_kex_filtered = FIPS_mode() ?
+ match_filter_allowlist(options.gss_kex_algorithms, GSS_KEX_DEFAULT_KEX_FIPS) : xstrdup(options.gss_kex_algorithms);
+
+ if (options.gss_server_identity) {
+ gss_host = xstrdup(options.gss_server_identity);
+ } else if (options.gss_trust_dns) {
+ gss_host = remote_hostname(ssh);
+ /* Fall back to specified host if we are using proxy command
+ * and can not use DNS on that socket */
+ if (strcmp(gss_host, "UNKNOWN") == 0) {
+ free(gss_host);
+ gss_host = xstrdup(host);
+ }
+ } else {
gss_host = xstrdup(host);
}
- } else {
- gss_host = xstrdup(host);
- }
- gss = ssh_gssapi_client_mechanisms(gss_host,
- options.gss_client_identity, options.gss_kex_algorithms);
- if (gss) {
- debug("Offering GSSAPI proposal: %s", gss);
- xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
- "%s,%s", gss, orig);
-
- /* If we've got GSSAPI algorithms, then we also support the
- * 'null' hostkey, as a last resort */
- orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
- xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
- "%s,null", orig);
+ gss = ssh_gssapi_client_mechanisms(gss_host,
+ options.gss_client_identity, options.gss_kex_algorithms);
+ if (gss) {
+ debug("Offering GSSAPI proposal: %s", gss);
+ xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
+ "%s,%s", gss, orig);
+
+ /* If we've got GSSAPI algorithms, then we also support the
+ * 'null' hostkey, as a last resort */
+ orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS];
+ xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS],
+ "%s,null", orig);
+ }
/* Add the GSSAPI mechanisms currently supported on this
* client to the key exchange algorithm proposal */
orig = myproposal[PROPOSAL_KEX_ALGS];
@@ -293,7 +299,9 @@ ssh_kex2(struct ssh *ssh, char *host, st
}
}
#endif
gss = ssh_gssapi_client_mechanisms(gss_host,
- options.gss_client_identity, options.gss_kex_algorithms);
+ options.gss_client_identity, gss_kex_filtered);
+ free(gss_kex_filtered);
+
if (gss) {
debug("Offering GSSAPI proposal: %s", gss);
xasprintf(&myproposal[PROPOSAL_KEX_ALGS],
diff -up openssh-8.6p1/sshd.c.fips openssh-8.6p1/sshd.c
--- openssh-8.6p1/sshd.c.fips 2021-05-06 12:08:36.493926838 +0200
+++ openssh-8.6p1/sshd.c 2021-05-06 12:13:56.501492639 +0200

6
openssh.spec
View File

@ -43,7 +43,7 @@
Summary: An open source implementation of SSH protocol version 2
Name: openssh
Version: %{openssh_ver}
Release: 11%{?dist}
Release: 12%{?dist}
URL: http://www.openssh.com/portable.html
Source0: ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-%{version}.tar.gz
Source1: ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-%{version}.tar.gz.asc
@ -686,6 +686,10 @@ test -f %{sysconfig_anaconda} && \
%attr(0755,root,root) %{_libdir}/sshtest/sk-dummy.so
%changelog
* Mon Aug 04 2025 Dmitry Belyavskiy <dbelyavs@redhat.com> - 9.9p1-12
- Relax GSS Kex restriction in FIPS mode
Resolves: RHEL-91181
* Fri Jul 18 2025 Zoltan Fridrich <zfridric@redhat.com> - 9.9p1-11
- Move the redhat help message to debug1 log level
Resolves: RHEL-93957