Apply destination constraints to all PKCS#11 keys

Resolves: CVE-2023-51384

openssh-9.6p1-CVE-2023-48795.patch

@@ -0,0 +1,443 @@
+diff --git a/PROTOCOL b/PROTOCOL
+index d453c779..ded935eb 100644
+--- a/PROTOCOL
++++ b/PROTOCOL
+@@ -137,6 +137,32 @@ than as a named global or channel request to allow pings with very
+ 
+ This is identical to curve25519-sha256 as later published in RFC8731.
+ 
++1.9 transport: strict key exchange extension
++
++OpenSSH supports a number of transport-layer hardening measures under
++a "strict KEX" feature. This feature is signalled similarly to the
++RFC8308 ext-info feature: by including a additional algorithm in the
++initiial SSH2_MSG_KEXINIT kex_algorithms field. The client may append
++"kex-strict-c-v00@openssh.com" to its kex_algorithms and the server
++may append "kex-strict-s-v00@openssh.com". These pseudo-algorithms
++are only valid in the initial SSH2_MSG_KEXINIT and MUST be ignored
++if they are present in subsequent SSH2_MSG_KEXINIT packets.
++
++When an endpoint that supports this extension observes this algorithm
++name in a peer's KEXINIT packet, it MUST make the following changes to
++the the protocol:
++
++a) During initial KEX, terminate the connection if any unexpected or
++   out-of-sequence packet is received. This includes terminating the
++   connection if the first packet received is not SSH2_MSG_KEXINIT.
++   Unexpected packets for the purpose of strict KEX include messages
++   that are otherwise valid at any time during the connection such as
++   SSH2_MSG_DEBUG and SSH2_MSG_IGNORE.
++b) After sending or receiving a SSH2_MSG_NEWKEYS message, reset the
++   packet sequence number to zero. This behaviour persists for the
++   duration of the connection (i.e. not just the first
++   SSH2_MSG_NEWKEYS).
++
+ 2. Connection protocol changes
+ 
+ 2.1. connection: Channel write close extension "eow@openssh.com"
+diff --git a/kex.c b/kex.c
+index aa5e792d..d478ff6e 100644
+--- a/kex.c
++++ b/kex.c
+@@ -65,7 +65,7 @@
+ #endif
+ 
+ /* prototype */
+-static int kex_choose_conf(struct ssh *);
++static int kex_choose_conf(struct ssh *, uint32_t seq);
+ static int kex_input_newkeys(int, u_int32_t, struct ssh *);
+ 
+ static const char * const proposal_names[PROPOSAL_MAX] = {
+@@ -177,6 +177,18 @@ kex_names_valid(const char *names)
+ 	return 1;
+ }
+ 
++/* returns non-zero if proposal contains any algorithm from algs */
++static int
++has_any_alg(const char *proposal, const char *algs)
++{
++	char *cp;
++
++	if ((cp = match_list(proposal, algs, NULL)) == NULL)
++		return 0;
++	free(cp);
++	return 1;
++}
++
+ /*
+  * Concatenate algorithm names, avoiding duplicates in the process.
+  * Caller must free returned string.
+@@ -184,7 +196,7 @@ kex_names_valid(const char *names)
+ char *
+ kex_names_cat(const char *a, const char *b)
+ {
+-	char *ret = NULL, *tmp = NULL, *cp, *p, *m;
++	char *ret = NULL, *tmp = NULL, *cp, *p;
+ 	size_t len;
+ 
+ 	if (a == NULL || *a == '\0')
+@@ -201,10 +213,8 @@ kex_names_cat(const char *a, const char *b)
+ 	}
+ 	strlcpy(ret, a, len);
+ 	for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
+-		if ((m = match_list(ret, p, NULL)) != NULL) {
+-			free(m);
++		if (has_any_alg(ret, p))
+ 			continue; /* Algorithm already present */
+-		}
+ 		if (strlcat(ret, ",", len) >= len ||
+ 		    strlcat(ret, p, len) >= len) {
+ 			free(tmp);
+@@ -334,15 +344,23 @@ kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
+ 	const char *defpropclient[PROPOSAL_MAX] = { KEX_CLIENT };
+ 	const char **defprop = ssh->kex->server ? defpropserver : defpropclient;
+ 	u_int i;
++	char *cp;
+ 
+ 	if (prop == NULL)
+ 		fatal_f("proposal missing");
+ 
++	/* Append EXT_INFO signalling to KexAlgorithms */
++	if (kexalgos == NULL)
++		kexalgos = defprop[PROPOSAL_KEX_ALGS];
++	if ((cp = kex_names_cat(kexalgos, ssh->kex->server ?
++	    "kex-strict-s-v00@openssh.com" :
++	    "ext-info-c,kex-strict-c-v00@openssh.com")) == NULL)
++		fatal_f("kex_names_cat");
++
+ 	for (i = 0; i < PROPOSAL_MAX; i++) {
+ 		switch(i) {
+ 		case PROPOSAL_KEX_ALGS:
+-			prop[i] = compat_kex_proposal(ssh,
+-			    kexalgos ? kexalgos : defprop[i]);
++			prop[i] = compat_kex_proposal(ssh, cp);
+ 			break;
+ 		case PROPOSAL_ENC_ALGS_CTOS:
+ 		case PROPOSAL_ENC_ALGS_STOC:
+@@ -363,6 +381,7 @@ kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
+ 			prop[i] = xstrdup(defprop[i]);
+ 		}
+ 	}
++	free(cp);
+ }
+ 
+ void
+@@ -466,7 +485,12 @@ kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
+ {
+ 	int r;
+ 
+-	error("kex protocol error: type %d seq %u", type, seq);
++	/* If in strict mode, any unexpected message is an error */
++	if ((ssh->kex->flags & KEX_INITIAL) && ssh->kex->kex_strict) {
++		ssh_packet_disconnect(ssh, "strict KEX violation: "
++		    "unexpected packet type %u (seqnr %u)", type, seq);
++	}
++	error_f("type %u seq %u", type, seq);
+ 	if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
+ 	    (r = sshpkt_put_u32(ssh, seq)) != 0 ||
+ 	    (r = sshpkt_send(ssh)) != 0)
+@@ -563,7 +587,7 @@ kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
+ 	if (ninfo >= 1024) {
+ 		error("SSH2_MSG_EXT_INFO with too many entries, expected "
+ 		    "<=1024, received %u", ninfo);
+-		return SSH_ERR_INVALID_FORMAT;
++		return dispatch_protocol_error(type, seq, ssh);
+ 	}
+ 	for (i = 0; i < ninfo; i++) {
+ 		if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
+@@ -681,7 +705,7 @@ kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
+ 		error_f("no kex");
+ 		return SSH_ERR_INTERNAL_ERROR;
+ 	}
+-	ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
++	ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_protocol_error);
+ 	ptr = sshpkt_ptr(ssh, &dlen);
+ 	if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
+ 		return r;
+@@ -717,7 +741,7 @@ kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
+ 	if (!(kex->flags & KEX_INIT_SENT))
+ 		if ((r = kex_send_kexinit(ssh)) != 0)
+ 			return r;
+-	if ((r = kex_choose_conf(ssh)) != 0)
++	if ((r = kex_choose_conf(ssh, seq)) != 0)
+ 		return r;
+ 
+ 	if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
+@@ -981,20 +1005,14 @@ proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
+ 	return (1);
+ }
+ 
+-/* returns non-zero if proposal contains any algorithm from algs */
+ static int
+-has_any_alg(const char *proposal, const char *algs)
++kexalgs_contains(char **peer, const char *ext)
+ {
+-	char *cp;
+-
+-	if ((cp = match_list(proposal, algs, NULL)) == NULL)
+-		return 0;
+-	free(cp);
+-	return 1;
++	return has_any_alg(peer[PROPOSAL_KEX_ALGS], ext);
+ }
+ 
+ static int
+-kex_choose_conf(struct ssh *ssh)
++kex_choose_conf(struct ssh *ssh, uint32_t seq)
+ {
+ 	struct kex *kex = ssh->kex;
+ 	struct newkeys *newkeys;
+@@ -1019,13 +1037,23 @@ kex_choose_conf(struct ssh *ssh)
+ 		sprop=peer;
+ 	}
+ 
+-	/* Check whether client supports ext_info_c */
+-	if (kex->server && (kex->flags & KEX_INITIAL)) {
+-		char *ext;
+-
+-		ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
+-		kex->ext_info_c = (ext != NULL);
+-		free(ext);
++	/* Check whether peer supports ext_info/kex_strict */
++	if ((kex->flags & KEX_INITIAL) != 0) {
++		if (kex->server) {
++			kex->ext_info_c = kexalgs_contains(peer, "ext-info-c");
++			kex->kex_strict = kexalgs_contains(peer,
++			    "kex-strict-c-v00@openssh.com");
++		} else {
++			kex->kex_strict = kexalgs_contains(peer,
++			    "kex-strict-s-v00@openssh.com");
++		}
++		if (kex->kex_strict) {
++			debug3_f("will use strict KEX ordering");
++			if (seq != 0)
++				ssh_packet_disconnect(ssh,
++				    "strict KEX violation: "
++				    "KEXINIT was not the first packet");
++		}
+ 	}
+ 
+ 	/* Check whether client supports rsa-sha2 algorithms */
+diff --git a/kex.h b/kex.h
+index 5f7ef784..272ebb43 100644
+--- a/kex.h
++++ b/kex.h
+@@ -149,6 +149,7 @@ struct kex {
+ 	u_int	kex_type;
+ 	char	*server_sig_algs;
+ 	int	ext_info_c;
++	int	kex_strict;
+ 	struct sshbuf *my;
+ 	struct sshbuf *peer;
+ 	struct sshbuf *client_version;
+diff --git a/packet.c b/packet.c
+index 52017def..beb214f9 100644
+--- a/packet.c
++++ b/packet.c
+@@ -1207,8 +1207,13 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
+ 	sshbuf_dump(state->output, stderr);
+ #endif
+ 	/* increment sequence number for outgoing packets */
+-	if (++state->p_send.seqnr == 0)
++	if (++state->p_send.seqnr == 0) {
++		if ((ssh->kex->flags & KEX_INITIAL) != 0) {
++			ssh_packet_disconnect(ssh, "outgoing sequence number "
++			    "wrapped during initial key exchange");
++		}
+ 		logit("outgoing seqnr wraps around");
++	}
+ 	if (++state->p_send.packets == 0)
+ 		if (!(ssh->compat & SSH_BUG_NOREKEY))
+ 			return SSH_ERR_NEED_REKEY;
+@@ -1216,6 +1221,11 @@ ssh_packet_send2_wrapped(struct ssh *ssh)
+ 	state->p_send.bytes += len;
+ 	sshbuf_reset(state->outgoing_packet);
+ 
++	if (type == SSH2_MSG_NEWKEYS && ssh->kex->kex_strict) {
++		debug_f("resetting send seqnr %u", state->p_send.seqnr);
++		state->p_send.seqnr = 0;
++	}
++
+ 	if (type == SSH2_MSG_NEWKEYS)
+ 		r = ssh_set_newkeys(ssh, MODE_OUT);
+ 	else if (type == SSH2_MSG_USERAUTH_SUCCESS && state->server_side)
+@@ -1344,8 +1354,7 @@ ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+ 	/* Stay in the loop until we have received a complete packet. */
+ 	for (;;) {
+ 		/* Try to read a packet from the buffer. */
+-		r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p);
+-		if (r != 0)
++		if ((r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p)) != 0)
+ 			break;
+ 		/* If we got a packet, return it. */
+ 		if (*typep != SSH_MSG_NONE)
+@@ -1629,10 +1615,16 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+ 		if ((r = sshbuf_consume(state->input, mac->mac_len)) != 0)
+ 			goto out;
+ 	}
++
+ 	if (seqnr_p != NULL)
+ 		*seqnr_p = state->p_read.seqnr;
+-	if (++state->p_read.seqnr == 0)
++	if (++state->p_read.seqnr == 0) {
++		if ((ssh->kex->flags & KEX_INITIAL) != 0) {
++			ssh_packet_disconnect(ssh, "incoming sequence number "
++			    "wrapped during initial key exchange");
++		}
+ 		logit("incoming seqnr wraps around");
++	}
+ 	if (++state->p_read.packets == 0)
+ 		if (!(ssh->compat & SSH_BUG_NOREKEY))
+ 			return SSH_ERR_NEED_REKEY;
+@@ -1698,6 +1690,10 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+ #endif
+ 	/* reset for next packet */
+ 	state->packlen = 0;
++	if (*typep == SSH2_MSG_NEWKEYS && ssh->kex->kex_strict) {
++		debug_f("resetting read seqnr %u", state->p_read.seqnr);
++		state->p_read.seqnr = 0;
++	}
+ 
+ 	if ((r = ssh_packet_check_rekey(ssh)) != 0)
+ 		return r;
+@@ -1720,10 +1716,39 @@ ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+ 		r = ssh_packet_read_poll2(ssh, typep, seqnr_p);
+ 		if (r != 0)
+ 			return r;
+-		if (*typep) {
+-			state->keep_alive_timeouts = 0;
+-			DBG(debug("received packet type %d", *typep));
++		if (*typep == 0) {
++			/* no message ready */
++			return 0;
+ 		}
++		state->keep_alive_timeouts = 0;
++		DBG(debug("received packet type %d", *typep));
++
++		/* Always process disconnect messages */
++		if (*typep == SSH2_MSG_DISCONNECT) {
++			if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
++			    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
++				return r;
++			/* Ignore normal client exit notifications */
++			do_log2(ssh->state->server_side &&
++			    reason == SSH2_DISCONNECT_BY_APPLICATION ?
++			    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
++			    "Received disconnect from %s port %d:"
++			    "%u: %.400s", ssh_remote_ipaddr(ssh),
++			    ssh_remote_port(ssh), reason, msg);
++			free(msg);
++			return SSH_ERR_DISCONNECTED;
++		}
++
++		/*
++		 * Do not implicitly handle any messages here during initial
++		 * KEX when in strict mode. They will be need to be allowed
++		 * explicitly by the KEX dispatch table or they will generate
++		 * protocol errors.
++		 */
++		if (ssh->kex != NULL &&
++		    (ssh->kex->flags & KEX_INITIAL) && ssh->kex->kex_strict)
++			return 0;
++		/* Implicitly handle transport-level messages */
+ 		switch (*typep) {
+ 		case SSH2_MSG_IGNORE:
+ 			debug3("Received SSH2_MSG_IGNORE");
+@@ -1738,19 +1763,6 @@ ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
+ 			debug("Remote: %.900s", msg);
+ 			free(msg);
+ 			break;
+-		case SSH2_MSG_DISCONNECT:
+-			if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
+-			    (r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
+-				return r;
+-			/* Ignore normal client exit notifications */
+-			do_log2(ssh->state->server_side &&
+-			    reason == SSH2_DISCONNECT_BY_APPLICATION ?
+-			    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
+-			    "Received disconnect from %s port %d:"
+-			    "%u: %.400s", ssh_remote_ipaddr(ssh),
+-			    ssh_remote_port(ssh), reason, msg);
+-			free(msg);
+-			return SSH_ERR_DISCONNECTED;
+ 		case SSH2_MSG_UNIMPLEMENTED:
+ 			if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0)
+ 				return r;
+@@ -2242,6 +2254,7 @@ kex_to_blob(struct sshbuf *m, struct kex *kex)
+ 	    (r = sshbuf_put_u32(m, kex->hostkey_type)) != 0 ||
+ 	    (r = sshbuf_put_u32(m, kex->hostkey_nid)) != 0 ||
+ 	    (r = sshbuf_put_u32(m, kex->kex_type)) != 0 ||
++	    (r = sshbuf_put_u32(m, kex->kex_strict)) != 0 ||
+ 	    (r = sshbuf_put_stringb(m, kex->my)) != 0 ||
+ 	    (r = sshbuf_put_stringb(m, kex->peer)) != 0 ||
+ 	    (r = sshbuf_put_stringb(m, kex->client_version)) != 0 ||
+@@ -2404,6 +2417,7 @@ kex_from_blob(struct sshbuf *m, struct kex **kexp)
+ 	    (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_type)) != 0 ||
+ 	    (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_nid)) != 0 ||
+ 	    (r = sshbuf_get_u32(m, &kex->kex_type)) != 0 ||
++	    (r = sshbuf_get_u32(m, &kex->kex_strict)) != 0 ||
+ 	    (r = sshbuf_get_stringb(m, kex->my)) != 0 ||
+ 	    (r = sshbuf_get_stringb(m, kex->peer)) != 0 ||
+ 	    (r = sshbuf_get_stringb(m, kex->client_version)) != 0 ||
+@@ -2732,6 +2746,7 @@ sshpkt_disconnect(struct ssh *ssh, const char *fmt,...)
+ 	vsnprintf(buf, sizeof(buf), fmt, args);
+ 	va_end(args);
+ 
++	debug2_f("sending SSH2_MSG_DISCONNECT: %s", buf);
+ 	if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
+ 	    (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 ||
+ 	    (r = sshpkt_put_cstring(ssh, buf)) != 0 ||
+diff --git a/sshconnect2.c b/sshconnect2.c
+index df6caf81..0cccbcc4 100644
+--- a/sshconnect2.c
++++ b/sshconnect2.c
+@@ -358,7 +358,6 @@ struct cauthmethod {
+ };
+ 
+ static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
+-static int input_userauth_ext_info(int, u_int32_t, struct ssh *);
+ static int input_userauth_success(int, u_int32_t, struct ssh *);
+ static int input_userauth_failure(int, u_int32_t, struct ssh *);
+ static int input_userauth_banner(int, u_int32_t, struct ssh *);
+@@ -472,7 +471,7 @@ ssh_userauth2(struct ssh *ssh, const char *local_user,
+ 
+ 	ssh->authctxt = &authctxt;
+ 	ssh_dispatch_init(ssh, &input_userauth_error);
+-	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
++	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info);
+ 	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
+ 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
+ 	pubkey_cleanup(ssh);
+@@ -531,12 +530,6 @@ input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
+ 	return r;
+ }
+ 
+-static int
+-input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
+-{
+-	return kex_input_ext_info(type, seqnr, ssh);
+-}
+-
+ void
+ userauth(struct ssh *ssh, char *authlist)
+ {
+@@ -615,6 +608,7 @@ input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
+ 	free(authctxt->methoddata);
+ 	authctxt->methoddata = NULL;
+ 	authctxt->success = 1;			/* break out */
++	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error);
+ 	return 0;
+ }
+ 
+diff -up openssh-8.7p1/sshd.c.kexstrict openssh-8.7p1/sshd.c
+--- openssh-8.7p1/sshd.c.kexstrict	2023-11-27 13:19:18.855433602 +0100
++++ openssh-8.7p1/sshd.c	2023-11-27 13:28:10.441325314 +0100
+@@ -2586,7 +2586,7 @@ do_ssh2_kex(struct ssh *ssh)
+ 	if (gss && orig)
+ 		xasprintf(&newstr, "%s,%s", gss, orig);
+ 	else if (gss)
+-		newstr = gss;
++		xasprintf(&newstr, "%s,%s", gss, "kex-strict-s-v00@openssh.com");
+ 	else if (orig)
+ 		newstr = orig;
+ 

openssh-9.6p1-CVE-2023-51384.patch

@@ -0,0 +1,149 @@
+diff --git a/ssh-agent.c b/ssh-agent.c
+index f528611635e..1d4c321eb0b 100644
+--- a/ssh-agent.c
++++ b/ssh-agent.c
+@@ -247,6 +247,91 @@ free_dest_constraints(struct dest_constraint *dcs, size_t ndcs)
+ 	free(dcs);
+ }
+ 
++static void
++dup_dest_constraint_hop(const struct dest_constraint_hop *dch,
++    struct dest_constraint_hop *out)
++{
++	u_int i;
++	int r;
++
++	out->user = dch->user == NULL ? NULL : xstrdup(dch->user);
++	out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname);
++	out->is_ca = dch->is_ca;
++	out->nkeys = dch->nkeys;
++	out->keys = out->nkeys == 0 ? NULL :
++	    xcalloc(out->nkeys, sizeof(*out->keys));
++	out->key_is_ca = out->nkeys == 0 ? NULL :
++	    xcalloc(out->nkeys, sizeof(*out->key_is_ca));
++	for (i = 0; i < dch->nkeys; i++) {
++		if (dch->keys[i] != NULL &&
++		    (r = sshkey_from_private(dch->keys[i],
++		    &(out->keys[i]))) != 0)
++			fatal_fr(r, "copy key");
++		out->key_is_ca[i] = dch->key_is_ca[i];
++	}
++}
++
++static struct dest_constraint *
++dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs)
++{
++	size_t i;
++	struct dest_constraint *ret;
++
++	if (ndcs == 0)
++		return NULL;
++	ret = xcalloc(ndcs, sizeof(*ret));
++	for (i = 0; i < ndcs; i++) {
++		dup_dest_constraint_hop(&dcs[i].from, &ret[i].from);
++		dup_dest_constraint_hop(&dcs[i].to, &ret[i].to);
++	}
++	return ret;
++}
++
++#ifdef DEBUG_CONSTRAINTS
++static void
++dump_dest_constraint_hop(const struct dest_constraint_hop *dch)
++{
++	u_int i;
++	char *fp;
++
++	debug_f("user %s hostname %s is_ca %d nkeys %u",
++	    dch->user == NULL ? "(null)" : dch->user,
++	    dch->hostname == NULL ? "(null)" : dch->hostname,
++	    dch->is_ca, dch->nkeys);
++	for (i = 0; i < dch->nkeys; i++) {
++		fp = NULL;
++		if (dch->keys[i] != NULL &&
++		    (fp = sshkey_fingerprint(dch->keys[i],
++		    SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL)
++			fatal_f("fingerprint failed");
++		debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys,
++		    dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]),
++		    dch->keys[i] == NULL ? "" : " ",
++		    dch->keys[i] == NULL ? "none" : fp,
++		    dch->key_is_ca[i]);
++		free(fp);
++	}
++}
++#endif /* DEBUG_CONSTRAINTS */
++
++static void
++dump_dest_constraints(const char *context,
++    const struct dest_constraint *dcs, size_t ndcs)
++{
++#ifdef DEBUG_CONSTRAINTS
++	size_t i;
++
++	debug_f("%s: %zu constraints", context, ndcs);
++	for (i = 0; i < ndcs; i++) {
++		debug_f("constraint %zu / %zu: from: ", i, ndcs);
++		dump_dest_constraint_hop(&dcs[i].from);
++		debug_f("constraint %zu / %zu: to: ", i, ndcs);
++		dump_dest_constraint_hop(&dcs[i].to);
++	}
++	debug_f("done for %s", context);
++#endif /* DEBUG_CONSTRAINTS */
++}
++
+ static void
+ free_identity(Identity *id)
+ {
+@@ -518,13 +603,22 @@ process_request_identities(SocketEntry *e)
+ 	Identity *id;
+ 	struct sshbuf *msg, *keys;
+ 	int r;
+-	u_int nentries = 0;
++	u_int i = 0, nentries = 0;
++	char *fp;
+ 
+ 	debug2_f("entering");
+ 
+ 	if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL)
+ 		fatal_f("sshbuf_new failed");
+ 	TAILQ_FOREACH(id, &idtab->idlist, next) {
++		if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT,
++		    SSH_FP_DEFAULT)) == NULL)
++			fatal_f("fingerprint failed");
++		debug_f("key %u / %u: %s %s", i++, idtab->nentries,
++		    sshkey_ssh_name(id->key), fp);
++		dump_dest_constraints(__func__,
++		    id->dest_constraints, id->ndest_constraints);
++		free(fp);
+ 		/* identity not visible, don't include in response */
+ 		if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
+ 			continue;
+@@ -1224,6 +1318,7 @@ process_add_identity(SocketEntry *e)
+ 		sshbuf_reset(e->request);
+ 		goto out;
+ 	}
++	dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
+ 
+ 	if (sk_provider != NULL) {
+ 		if (!sshkey_is_sk(k)) {
+@@ -1403,6 +1498,7 @@ process_add_smartcard_key(SocketEntry *e)
+ 		error_f("failed to parse constraints");
+ 		goto send;
+ 	}
++	dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
+ 
+ 	sane_uri = sanitize_pkcs11_provider(e, provider);
+ 	if (sane_uri == NULL)
+@@ -1438,10 +1534,9 @@ process_add_smartcard_key(SocketEntry *e)
+ 			}
+ 			id->death = death;
+ 			id->confirm = confirm;
+-			id->dest_constraints = dest_constraints;
++			id->dest_constraints = dup_dest_constraints(
++			    dest_constraints, ndest_constraints);
+ 			id->ndest_constraints = ndest_constraints;
+-			dest_constraints = NULL; /* transferred */
+-			ndest_constraints = 0;
+ 			TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
+ 			idtab->nentries++;
+ 			success = 1;

openssh-9.6p1-CVE-2023-51385.patch

@@ -0,0 +1,57 @@
+diff --git a/ssh.c b/ssh.c
+index 35c48e62..48d93ddf 100644
+--- a/ssh.c
++++ b/ssh.c
+@@ -626,6 +626,41 @@ ssh_conn_info_free(struct ssh_conn_info *cinfo)
+ 	free(cinfo);
+ }
+ 
++static int
++valid_hostname(const char *s)
++{
++	size_t i;
++
++	if (*s == '-')
++		return 0;
++	for (i = 0; s[i] != 0; i++) {
++		if (strchr("'`\"$\\;&<>|(){}", s[i]) != NULL ||
++		    isspace((u_char)s[i]) || iscntrl((u_char)s[i]))
++			return 0;
++	}
++	return 1;
++}
++
++static int
++valid_ruser(const char *s)
++{
++	size_t i;
++
++	if (*s == '-')
++		return 0;
++	for (i = 0; s[i] != 0; i++) {
++		if (strchr("'`\";&<>|(){}", s[i]) != NULL)
++			return 0;
++		/* Disallow '-' after whitespace */
++		if (isspace((u_char)s[i]) && s[i + 1] == '-')
++			return 0;
++		/* Disallow \ in last position */
++		if (s[i] == '\\' && s[i + 1] == '\0')
++			return 0;
++	}
++	return 1;
++}
++
+ /*
+  * Main program for the ssh client.
+  */
+@@ -1118,6 +1153,10 @@ main(int ac, char **av)
+ 	if (!host)
+ 		usage();
+ 
++	if (!valid_hostname(host))
++		fatal("hostname contains invalid characters");
++	if (options.user != NULL && !valid_ruser(options.user))
++		fatal("remote username contains invalid characters");
+ 	options.host_arg = xstrdup(host);
+ 
+ 	/* Initialize the command to execute on remote host. */

openssh.spec

@@ -47,7 +47,7 @@
 
 # Do not forget to bump pam_ssh_agent_auth release if you rewind the main package release to 1
 %global openssh_ver 9.3p1
-%global openssh_rel 8
+%global openssh_rel 10
 %global pam_ssh_agent_ver 0.10.4
 %global pam_ssh_agent_rel 9
 
@@ -66,6 +66,7 @@ Source5: pam_ssh_agent-rmheaders
 Source6: ssh-keycat.pam
 Source7: sshd.sysconfig
 Source9: sshd@.service
+Source10: sshd.socket
 Source11: sshd.service
 Source12: sshd-keygen@.service
 Source13: sshd-keygen
@@ -230,6 +231,9 @@ Patch1014: openssh-8.7p1-nohostsha1proof.patch
 Patch1015: openssh-9.3p1-upstream-cve-2023-38408.patch
 # upstream b7afd8a4ecaca8afd3179b55e9db79c0ff210237
 Patch1016: openssh-9.3p1-openssl-compat.patch
+Patch1017: openssh-9.6p1-CVE-2023-51385.patch
+Patch1018: openssh-9.6p1-CVE-2023-48795.patch
+Patch1019: openssh-9.6p1-CVE-2023-51384.patch
 
 License: BSD
 Requires: /sbin/nologin
@@ -434,6 +438,9 @@ popd
 %patch -P 1014 -p1 -b .nosha1hostproof
 %patch -P 1015 -p1 -b .cve-2023-38408
 %patch -P 1016 -p1 -b .ossl-version
+%patch -P 1017 -p1 -b .cve-2023-51385
+%patch -P 1018 -p1 -b .cve-2023-48795
+%patch -P 1019 -p1 -b .cve-2023-51384
 
 %patch -P 100 -p1 -b .coverity
 
@@ -573,6 +580,7 @@ install -m644 sshd_config_redhat_cp $RPM_BUILD_ROOT%{_sysconfdir}/ssh/sshd_confi
 install -m644 sshd_config_redhat $RPM_BUILD_ROOT%{_sysconfdir}/ssh/sshd_config.d/50-redhat.conf
 install -d -m755 $RPM_BUILD_ROOT/%{_unitdir}
 install -m644 %{SOURCE9} $RPM_BUILD_ROOT/%{_unitdir}/sshd@.service
+install -m644 %{SOURCE10} $RPM_BUILD_ROOT/%{_unitdir}/sshd.socket
 install -m644 %{SOURCE11} $RPM_BUILD_ROOT/%{_unitdir}/sshd.service
 install -m644 %{SOURCE12} $RPM_BUILD_ROOT/%{_unitdir}/sshd-keygen@.service
 install -m644 %{SOURCE15} $RPM_BUILD_ROOT/%{_unitdir}/sshd-keygen.target
@@ -630,7 +638,7 @@ if [ $1 -gt 1 ]; then
     # OSTree systems) from running.
     touch /var/lib/.ssh-host-keys-migration
 fi
-%systemd_post sshd.service
+%systemd_post sshd.service sshd.socket
 # Migration scriptlet for Fedora 31 and 32 installations to sshd_config
 # drop-in directory (in F32+).
 # Do this only if the file generated by anaconda exists, contains our config
@@ -644,7 +652,7 @@ test -f %{sysconfig_anaconda} && \
   rm %{sysconfig_anaconda} || :
 
 %preun server
-%systemd_preun sshd.service
+%systemd_preun sshd.service sshd.socket
 
 %postun server
 %systemd_postun_with_restart sshd.service
@@ -711,6 +719,7 @@ test -f %{sysconfig_anaconda} && \
 %attr(0640,root,root) %config(noreplace) /etc/sysconfig/sshd
 %attr(0644,root,root) %{_unitdir}/sshd.service
 %attr(0644,root,root) %{_unitdir}/sshd@.service
+%attr(0644,root,root) %{_unitdir}/sshd.socket
 %attr(0644,root,root) %{_unitdir}/sshd-keygen@.service
 %attr(0644,root,root) %{_unitdir}/sshd-keygen.target
 %attr(0644,root,root) %{_sysusersdir}/openssh-server.conf
@@ -741,6 +750,17 @@ test -f %{sysconfig_anaconda} && \
 %endif
 
 %changelog
+* Wed Jan 10 2024 Dmitry Belyavskiy <dbelyavs@redhat.com> - 9.3p1-10
+- Forbid shell metasymbols in username/hostname
+  Resolves: CVE-2023-51385
+- Fix Terrapin attack
+  Resolves: CVE-2023-48795
+- Apply destination constraints to all PKCS#11 keys
+  Resolves: CVE-2023-51384
+
+* Fri Sep 08 2023 Dmitry Belyavskiy <dbelyavs@redhat.com> - 9.3p1-9
+- Revert "Remove sshd.socket unit (rhbz#2025716)" according to FESCO decision
+
 * Thu Aug 03 2023 Dmitry Belyavskiy <dbelyavs@redhat.com> - 9.3p1-8
 - Split including crypto-policies to a separate config (rhbz#1970566)
 - Disable forking of ssh-agent on startup (rhbz#2148555)

sshd.socket

@@ -0,0 +1,11 @@
+[Unit]
+Description=OpenSSH Server Socket
+Documentation=man:sshd(8) man:sshd_config(5)
+Conflicts=sshd.service
+
+[Socket]
+ListenStream=22
+Accept=yes
+
+[Install]
+WantedBy=sockets.target