Fix issue with read-only ssh buffer during gssapi key exchange

Clean up HPN patch

.gitignore

@@ -1,4 +1,4 @@
 /*.tar.bz2
 /*.tar.gz
 /*.tar.gz.asc
-/DJM-GPG-KEY.gpg
+/*.gpg

gsi-openssh.spec

@@ -31,7 +31,7 @@
 %global ldap 1
 
 %global openssh_ver 8.3p1
-%global openssh_rel 3
+%global openssh_rel 5
 
 Summary: An implementation of the SSH protocol with GSI authentication
 Name: gsi-openssh
@@ -163,10 +163,17 @@ Patch966: openssh-8.2p1-x11-without-ipv6.patch
 # Unbreak sshd_config include corner cases (#3122)
 Patch967: openssh-8.3p1-sshd_include.patch
 
+# Fix issue with read-only ssh buffer during gssapi key exchange (#1938224)
+# https://github.com/openssh-gsskex/openssh-gsskex/pull/19
+Patch97: openssh-8.0p1-sshbuf-readonly.patch
 # This is the patch that adds GSI support
 # Based on hpn_isshd-gsi.7.5p1b.patch from Globus upstream
 Patch98: openssh-8.3p1-gsissh.patch
 
+# This is the HPN patch
+# Based on https://sourceforge.net/projects/hpnssh/files/Patches/HPN-SSH%2014v22%208.3p1/
+Patch99: openssh-8.3p1-hpn-14.22-modified.patch
+
 License: BSD
 Requires: /sbin/nologin
 
@@ -317,7 +324,9 @@ gpgv2 --quiet --keyring %{SOURCE3} %{SOURCE1} %{SOURCE0}
 
 %patch100 -p1 -b .coverity
 
+%patch97 -p1 -b .sshbuf-ro
 %patch98 -p1 -b .gsi
+%patch99 -p1 -b .hpn
 
 sed 's/sshd.pid/gsisshd.pid/' -i pathnames.h
 sed 's!$(piddir)/sshd.pid!$(piddir)/gsisshd.pid!' -i Makefile.in
@@ -474,7 +483,7 @@ getent passwd sshd >/dev/null || \
 
 %files
 %license LICENCE
-%doc CREDITS ChangeLog OVERVIEW PROTOCOL* README README.platform README.privsep README.tun README.dns README.sshd-and-gsisshd TODO
+%doc CREDITS ChangeLog OVERVIEW PROTOCOL* README HPN-README README.platform README.privsep README.tun README.dns README.sshd-and-gsisshd TODO
 %attr(0755,root,root) %dir %{_sysconfdir}/gsissh
 %attr(0644,root,root) %config(noreplace) %{_sysconfdir}/gsissh/moduli
 %attr(0755,root,root) %{_bindir}/gsissh-keygen
@@ -517,6 +526,13 @@ getent passwd sshd >/dev/null || \
 %attr(0644,root,root) %{_tmpfilesdir}/gsissh.conf
 
 %changelog
+* Tue Mar 16 2021 Mattias Ellert <mattias.ellert@physics.uu.se> - 8.3p1-5
+- Fix issue with read-only ssh buffer during gssapi key exchange
+- Clean up HPN patch
+
+* Thu Oct 29 2020 Frank Scheiner <scheiner@hlrs.de> - 8.3p1-4
+- Add HPN patch
+
 * Thu Jun 11 2020 Mattias Ellert <mattias.ellert@physics.uu.se> - 8.3p1-3
 - Based on openssh-8.3p1-3.fc32
 

openssh-8.0p1-sshbuf-readonly.patch

@@ -0,0 +1,152 @@
+From 063e1a255b53abde1147522f9aceccfd2a7ceb9b Mon Sep 17 00:00:00 2001
+From: Jakub Jelen <jjelen@redhat.com>
+Date: Tue, 2 Mar 2021 19:45:25 +0100
+Subject: [PATCH] Unbreak gsi-openssh by not holding the sshbuf structures
+ originated from incoming packet buffer
+
+Keeping buffers from sshpkt_getb_froms() for breaks further packet
+processing because the "derived" buffer keeps a "link" to te parent
+buffer, which is then considered readonly.
+
+This addresses the visible issue in the kexgss_server(), which
+demonstrated with GSI (requiring more round trips than GSSAPI
+with kerberos).
+
+The additional two places in the client were never hit, because the host
+keys are never sent as part of the gssapi key exchange but in case we
+would have different server or we would start sending hostkeys as the
+code is ready for that, we would hit it anyway.
+
+Fixes #18
+---
+ kexgssc.c | 14 ++++++++++++--
+ kexgsss.c | 48 ++++++++++++++++++++++++++++--------------------
+ 2 files changed, 40 insertions(+), 22 deletions(-)
+
+diff --git a/kexgssc.c b/kexgssc.c
+index 1c62740e..29b8b031 100644
+--- a/kexgssc.c
++++ b/kexgssc.c
+@@ -162,11 +162,16 @@ kexgss_client(struct ssh *ssh)
+ 			do {
+ 				type = ssh_packet_read(ssh);
+ 				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
++					char *tmp = NULL;
++					size_t tmp_len = 0;
++
+ 					debug("Received KEXGSS_HOSTKEY");
+ 					if (server_host_key_blob)
+ 						fatal("Server host key received more than once");
+-					if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
++					if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0)
+ 						fatal("Failed to read server host key: %s", ssh_err(r));
++					if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL)
++						fatal("sshbuf_from failed");
+ 				}
+ 			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
+ 
+@@ -453,11 +458,16 @@ kexgssgex_client(struct ssh *ssh)
+ 			do {
+ 				type = ssh_packet_read(ssh);
+ 				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
++					char *tmp = NULL;
++					size_t tmp_len = 0;
++
+ 					debug("Received KEXGSS_HOSTKEY");
+ 					if (server_host_key_blob)
+ 						fatal("Server host key received more than once");
+-					if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
++					if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0)
+ 						fatal("sshpkt failed: %s", ssh_err(r));
++					if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL)
++						fatal("sshbuf_from failed");
+ 				}
+ 			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
+ 
+diff --git a/kexgsss.c b/kexgsss.c
+index a2c02148..c8b7d652 100644
+--- a/kexgsss.c
++++ b/kexgsss.c
+@@ -64,7 +64,7 @@ kexgss_server(struct ssh *ssh)
+ 	 */
+ 
+ 	OM_uint32 ret_flags = 0;
+-	gss_buffer_desc gssbuf, recv_tok, msg_tok;
++	gss_buffer_desc gssbuf = {0, NULL}, recv_tok, msg_tok;
+ 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ 	Gssctxt *ctxt = NULL;
+ 	struct sshbuf *shared_secret = NULL;
+@@ -104,7 +104,7 @@ kexgss_server(struct ssh *ssh)
+ 		type = ssh_packet_read(ssh);
+ 		switch(type) {
+ 		case SSH2_MSG_KEXGSS_INIT:
+-			if (client_pubkey != NULL)
++			if (gssbuf.value != NULL)
+ 				fatal("Received KEXGSS_INIT after initialising");
+ 			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+ 			        &recv_tok)) != 0 ||
+@@ -135,6 +135,31 @@ kexgss_server(struct ssh *ssh)
+ 				goto out;
+ 
+ 			/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
++
++			/* Calculate the hash early so we can free the
++			* client_pubkey, which has reference to the parent
++			* buffer state->incoming_packet
++			*/
++			hashlen = sizeof(hash);
++			if ((r = kex_gen_hash(
++			    kex->hash_alg,
++			    kex->client_version,
++			    kex->server_version,
++			    kex->peer,
++			    kex->my,
++			    empty,
++			    client_pubkey,
++			    server_pubkey,
++			    shared_secret,
++			    hash, &hashlen)) != 0)
++				goto out;
++
++			gssbuf.value = hash;
++			gssbuf.length = hashlen;
++
++			sshbuf_free(client_pubkey);
++			client_pubkey = NULL;
++
+ 			break;
+ 		case SSH2_MSG_KEXGSS_CONTINUE:
+ 			if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
+@@ -156,7 +181,7 @@ kexgss_server(struct ssh *ssh)
+ 		if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
+ 			fatal("Zero length token output when incomplete");
+ 
+-		if (client_pubkey == NULL)
++		if (gssbuf.value == NULL)
+ 			fatal("No client public key");
+ 
+ 		if (maj_status & GSS_S_CONTINUE_NEEDED) {
+@@ -185,23 +210,6 @@ kexgss_server(struct ssh *ssh)
+ 	if (!(ret_flags & GSS_C_INTEG_FLAG))
+ 		fatal("Integrity flag wasn't set");
+ 
+-	hashlen = sizeof(hash);
+-	if ((r = kex_gen_hash(
+-	    kex->hash_alg,
+-	    kex->client_version,
+-	    kex->server_version,
+-	    kex->peer,
+-	    kex->my,
+-	    empty,
+-	    client_pubkey,
+-	    server_pubkey,
+-	    shared_secret,
+-	    hash, &hashlen)) != 0)
+-		goto out;
+-
+-	gssbuf.value = hash;
+-	gssbuf.length = hashlen;
+-
+ 	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
+ 		fatal("Couldn't get MIC");
+