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Fix SSH connection to localhost not possible in FIPS

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Related: rhbz#2031868
This commit is contained in:
Dmitry Belyavskiy 2021-12-16 17:01:04 +01:00
parent bf1985329d
commit 829ee6e4ad
2 changed files with 111 additions and 1 deletions
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102
openssh-8.7p1-minimize-sha1-use.patch Normal file
View File

@ -0,0 +1,102 @@
diff -up openssh-8.7p1/kex.c.minsha1 openssh-8.7p1/kex.c
--- openssh-8.7p1/kex.c.minsha1 2021-12-20 17:38:51.438294309 +0100
+++ openssh-8.7p1/kex.c 2021-12-21 11:02:48.379991319 +0100
@@ -994,6 +994,35 @@ kex_choose_conf(struct ssh *ssh)
free(ext);
}
+ /* Check whether client supports rsa-sha2 algorithms */
+ if (kex->server && (kex->flags & KEX_INITIAL)) {
+ char *ext;
+
+ ext = match_list("rsa-sha2-256", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
+ if (ext) {
+ kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
+ free(ext);
+ }
+
+ ext = match_list("rsa-sha2-512", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
+ if (ext) {
+ kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
+ free(ext);
+ }
+
+ ext = match_list("rsa-sha2-256-cert-v01@openssh.com", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
+ if (ext) {
+ kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
+ free(ext);
+ }
+
+ ext = match_list("rsa-sha2-512-cert-v01@openssh.com", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
+ if (ext) {
+ kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
+ free(ext);
+ }
+ }
+
/* Algorithm Negotiation */
if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
sprop[PROPOSAL_KEX_ALGS])) != 0) {
diff -up openssh-8.7p1/kex.h.minsha1 openssh-8.7p1/kex.h
--- openssh-8.7p1/kex.h.minsha1 2021-12-20 17:38:51.430294240 +0100
+++ openssh-8.7p1/kex.h 2021-12-21 10:56:29.066735608 +0100
@@ -116,6 +116,8 @@ enum kex_exchange {
#define KEX_INIT_SENT 0x0001
#define KEX_INITIAL 0x0002
+#define KEX_RSA_SHA2_256_SUPPORTED 0x0004
+#define KEX_RSA_SHA2_512_SUPPORTED 0x0008
struct sshenc {
char *name;
diff -up openssh-8.7p1/serverloop.c.minsha1 openssh-8.7p1/serverloop.c
--- openssh-8.7p1/serverloop.c.minsha1 2021-08-20 06:03:49.000000000 +0200
+++ openssh-8.7p1/serverloop.c 2021-12-21 11:01:00.594047538 +0100
@@ -684,7 +685,7 @@ server_input_hostkeys_prove(struct ssh *
struct sshbuf *resp = NULL;
struct sshbuf *sigbuf = NULL;
struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
- int r, ndx, kexsigtype, use_kexsigtype, success = 0;
+ int r, ndx, success = 0;
const u_char *blob;
u_char *sig = 0;
size_t blen, slen;
@@ -692,9 +693,11 @@ server_input_hostkeys_prove(struct ssh *
if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
fatal_f("sshbuf_new");
- kexsigtype = sshkey_type_plain(
- sshkey_type_from_name(ssh->kex->hostkey_alg));
while (ssh_packet_remaining(ssh) > 0) {
+ const char *pkexstr = NULL;
+ const char *rsa_sha2_256 = "rsa-sha2-256";
+ const char *rsa_sha2_512 = "rsa-sha2-512";
+
sshkey_free(key);
key = NULL;
if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
@@ -726,8 +729,13 @@ server_input_hostkeys_prove(struct ssh *
* For RSA keys, prefer to use the signature type negotiated
* during KEX to the default (SHA1).
*/
- use_kexsigtype = kexsigtype == KEY_RSA &&
- sshkey_type_plain(key->type) == KEY_RSA;
+ if (sshkey_type_plain(key->type) == KEY_RSA) {
+ if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
+ pkexstr = rsa_sha2_512;
+ else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
+ pkexstr = rsa_sha2_256;
+ }
+
if ((r = sshbuf_put_cstring(sigbuf,
"hostkeys-prove-00@openssh.com")) != 0 ||
(r = sshbuf_put_stringb(sigbuf,
@@ -735,7 +743,7 @@ server_input_hostkeys_prove(struct ssh *
(r = sshkey_puts(key, sigbuf)) != 0 ||
(r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
- use_kexsigtype ? ssh->kex->hostkey_alg : NULL)) != 0 ||
+ pkexstr)) != 0 ||
(r = sshbuf_put_string(resp, sig, slen)) != 0) {
error_fr(r, "assemble signature");
goto out;

10
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 # 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_ver 8.7p1
%global openssh_rel 5 %global openssh_rel 6
%global pam_ssh_agent_ver 0.10.4 %global pam_ssh_agent_ver 0.10.4
%global pam_ssh_agent_rel 4 %global pam_ssh_agent_rel 4
@ -202,6 +202,8 @@ Patch978: openssh-8.7p1-upstream-cve-2021-41617.patch
# fix for `ssh-keygen -Y find-principals -f /dev/null -s /dev/null` (#2024902) # fix for `ssh-keygen -Y find-principals -f /dev/null -s /dev/null` (#2024902)
Patch979: openssh-8.7p1-find-principals-fix.patch Patch979: openssh-8.7p1-find-principals-fix.patch
Patch1000: openssh-8.7p1-minimize-sha1-use.patch
License: BSD License: BSD
Requires: /sbin/nologin Requires: /sbin/nologin
@ -385,6 +387,8 @@ popd
%patch201 -p1 -b .audit-race %patch201 -p1 -b .audit-race
%patch700 -p1 -b .fips %patch700 -p1 -b .fips
%patch1000 -p1 -b .minsha1
%patch100 -p1 -b .coverity %patch100 -p1 -b .coverity
autoreconf autoreconf
@ -664,6 +668,10 @@ test -f %{sysconfig_anaconda} && \
%endif %endif
%changelog %changelog
* Tue Dec 21 2021 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-6
- Fix SSH connection to localhost not possible in FIPS
Related: rhbz#2031868
* Mon Nov 29 2021 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-5 * Mon Nov 29 2021 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-5
- Fix `ssh-keygen -Y find-principals -f /dev/null -s /dev/null` segfault - Fix `ssh-keygen -Y find-principals -f /dev/null -s /dev/null` segfault
Related: rhbz#2024902 Related: rhbz#2024902