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Don't propose disallowed algorithms during hostkey negotiation 

Resolves: rhbz#2068423

Signed-off-by: Zoltan Fridrich <zfridric@redhat.com>
This commit is contained in:
Zoltan Fridrich 2022-07-12 16:50:40 +02:00
parent b17ff3bc91
commit e8622f8c21
2 changed files with 73 additions and 1 deletions
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63
openssh-8.7p1-negotiate-supported-algs.patch Normal file
View File

@ -0,0 +1,63 @@
diff --color -rup a/regress/hostkey-agent.sh b/regress/hostkey-agent.sh
--- a/regress/hostkey-agent.sh 2021-08-20 06:03:49.000000000 +0200
+++ b/regress/hostkey-agent.sh 2022-07-14 11:58:12.172786060 +0200
@@ -13,8 +13,12 @@ r=$?
grep -vi 'hostkey' $OBJ/sshd_proxy > $OBJ/sshd_proxy.orig
echo "HostKeyAgent $SSH_AUTH_SOCK" >> $OBJ/sshd_proxy.orig
+PUBKEY_ACCEPTED_ALGOS=`$SSH -G "example.com" | \
+ grep -i "PubkeyAcceptedAlgorithms" | cut -d ' ' -f2- | tr "," "|"`
+SSH_ACCEPTED_KEYTYPES=`echo "$SSH_KEYTYPES" | egrep "$PUBKEY_ACCEPTED_ALGOS"`
+
trace "load hostkeys"
-for k in $SSH_KEYTYPES ; do
+for k in $SSH_ACCEPTED_KEYTYPES ; do
${SSHKEYGEN} -qt $k -f $OBJ/agent-key.$k -N '' || fatal "ssh-keygen $k"
(
printf 'localhost-with-alias,127.0.0.1,::1 '
@@ -31,7 +35,7 @@ cp $OBJ/known_hosts.orig $OBJ/known_host
unset SSH_AUTH_SOCK
for ps in yes; do
- for k in $SSH_KEYTYPES ; do
+ for k in $SSH_ACCEPTED_KEYTYPES ; do
verbose "key type $k privsep=$ps"
cp $OBJ/sshd_proxy.orig $OBJ/sshd_proxy
echo "UsePrivilegeSeparation $ps" >> $OBJ/sshd_proxy
diff --color -rup a/sshconnect2.c b/sshconnect2.c
--- a/sshconnect2.c 2022-07-14 10:10:07.262975710 +0200
+++ b/sshconnect2.c 2022-07-14 10:10:32.068452067 +0200
@@ -222,6 +222,7 @@ ssh_kex2(struct ssh *ssh, char *host, st
{
char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
char *s, *all_key;
+ char *hostkeyalgs = NULL, *pkalg = NULL;
char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL;
int r, use_known_hosts_order = 0;
@@ -264,14 +265,19 @@ ssh_kex2(struct ssh *ssh, char *host, st
myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
if (use_known_hosts_order) {
/* Query known_hosts and prefer algorithms that appear there */
- myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
- compat_pkalg_proposal(ssh,
- order_hostkeyalgs(host, hostaddr, port, cinfo));
+ if ((hostkeyalgs = order_hostkeyalgs(host, hostaddr, port, cinfo)) == NULL)
+ fatal_f("order_hostkeyalgs");
+ pkalg = match_filter_allowlist(hostkeyalgs, options.pubkey_accepted_algos);
+ free(hostkeyalgs);
} else {
- /* Use specified HostkeyAlgorithms exactly */
- myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
- compat_pkalg_proposal(ssh, options.hostkeyalgorithms);
+ /* Use specified HostkeyAlgorithms */
+ pkalg = match_filter_allowlist(options.hostkeyalgorithms, options.pubkey_accepted_algos);
}
+ if (pkalg == NULL)
+ fatal_f("match_filter_allowlist");
+ myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey =
+ compat_pkalg_proposal(ssh, pkalg);
+ free(pkalg);
#if defined(GSSAPI) && defined(WITH_OPENSSL)
if (options.gss_keyex) {

11
openssh.spec
View File

@ -51,7 +51,7 @@
# Do not forget to bump pam_ssh_agent_auth release if you rewind the main package release to 1
%global openssh_ver 8.7p1
%global openssh_rel 15
%global openssh_rel 16
%global pam_ssh_agent_ver 0.10.4
%global pam_ssh_agent_rel 4
@ -246,6 +246,10 @@ Patch1004: openssh-8.7p1-gssapi-auth.patch
# d9dbb5d9a0326e252d3c7bc13beb9c2434f59409
# fdb1d58d0d3888b042e5a500f6ce524486aaf782
Patch1005: openssh-8.7p1-host-based-auth.patch
# Don't propose disallowed algorithms during hostkey negotiation
# upstream MR:
# https://github.com/openssh/openssh-portable/pull/323
Patch1006: openssh-8.7p1-negotiate-supported-algs.patch
License: BSD
Requires: /sbin/nologin
@ -440,6 +444,7 @@ popd
%patch1003 -p1 -b .mem-leak
%patch1004 -p1 -b .gssapi-auth
%patch1005 -p1 -b .host-based-auth
%patch1006 -p1 -b .negotiate-supported-algs
%patch100 -p1 -b .coverity
@ -720,6 +725,10 @@ test -f %{sysconfig_anaconda} && \
%endif
%changelog
* Thu Jul 14 2022 Zoltan Fridrich <zfridric@redhat.com> - 8.7p1-16
- Don't propose disallowed algorithms during hostkey negotiation
Resolves: rhbz#2068423
* Thu Jul 14 2022 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-15
- Disable ed25519 and ed25519-sk keys in FIPS mode
Related: rhbz#2087915