Adding debian version 1:8.4p1-5+deb11u3.debian/1%8.4p1-5+deb11u3debian

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 460 insertions, 0 deletions

diff --git a/debian/patches/CVE-2023-48795.patch b/debian/patches/CVE-2023-48795.patch
new file mode 100644
index 0000000..8f14f86
--- /dev/null
+++ b/debian/patches/CVE-2023-48795.patch
@@ -0,0 +1,460 @@
+From 802a7af111c9ddb438ca4fd8c5cc35534e199fda Mon Sep 17 00:00:00 2001
+From: "djm@openbsd.org" <djm@openbsd.org>
+Date: Mon, 18 Dec 2023 14:45:17 +0000
+Subject: upstream: implement "strict key exchange" in ssh and sshd
+
+This adds a protocol extension to improve the integrity of the SSH
+transport protocol, particular in and around the initial key exchange
+(KEX) phase.
+
+Full details of the extension are in the PROTOCOL file.
+
+with markus@
+
+OpenBSD-Commit-ID: 2a66ac962f0a630d7945fee54004ed9e9c439f14
+
+Origin: backport, https://anongit.mindrot.org/openssh.git/commit/?id=1edb00c58f8a6875fad6a497aa2bacf37f9e6cd5
+Last-Update: 2023-12-21
+
+Patch-Name: CVE-2023-48795.patch
+---
+ PROTOCOL      | 26 +++++++++++++++++
+ kex.c         | 68 ++++++++++++++++++++++++++++++++-----------
+ kex.h         |  1 +
+ packet.c      | 80 ++++++++++++++++++++++++++++++++++++++-------------
+ sshconnect2.c | 14 +++------
+ sshd.c        |  8 ++++--
+ 6 files changed, 149 insertions(+), 48 deletions(-)
+
+diff --git a/PROTOCOL b/PROTOCOL
+index ecdacb9dc..bbe7ea560 100644
+--- a/PROTOCOL
++++ b/PROTOCOL
+@@ -102,6 +102,32 @@ OpenSSH supports the use of ECDH in Curve25519 for key exchange as
+ described at:
+ http://git.libssh.org/users/aris/libssh.git/plain/doc/curve25519-sha256@libssh.org.txt?h=curve25519
+ 
++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 763c45536..bda0473f7 100644
+--- a/kex.c
++++ b/kex.c
+@@ -68,7 +68,7 @@
+ #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 *proposal_names[PROPOSAL_MAX] = {
+@@ -207,6 +207,18 @@ 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.
+@@ -214,7 +226,7 @@ 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')
+@@ -231,10 +243,8 @@ 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);
+@@ -466,7 +476,12 @@ 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("%s: type %u seq %u", __func__, type, seq);
+ 	if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
+ 	    (r = sshpkt_put_u32(ssh, seq)) != 0 ||
+ 	    (r = sshpkt_send(ssh)) != 0)
+@@ -538,6 +553,11 @@ kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
+ 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
+ 	if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
+ 		return r;
++	if (ninfo >= 1024) {
++		error("SSH2_MSG_EXT_INFO with too many entries, expected "
++		    "<=1024, received %u", ninfo);
++		return dispatch_protocol_error(type, seq, ssh);
++	}
+ 	for (i = 0; i < ninfo; i++) {
+ 		if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
+ 			return r;
+@@ -638,7 +658,7 @@ kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
+ 		error("%s: no hex", __func__);
+ 		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;
+@@ -674,7 +694,7 @@ 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)
+@@ -939,7 +959,13 @@ proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
+ }
+ 
+ static int
+-kex_choose_conf(struct ssh *ssh)
++kexalgs_contains(char **peer, const char *ext)
++{
++	return has_any_alg(peer[PROPOSAL_KEX_ALGS], ext);
++}
++
++static int
++kex_choose_conf(struct ssh *ssh, uint32_t seq)
+ {
+ 	struct kex *kex = ssh->kex;
+ 	struct newkeys *newkeys;
+@@ -964,13 +990,23 @@ 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("%s: will use strict KEX ordering", __func__);
++			if (seq != 0)
++				ssh_packet_disconnect(ssh,
++				    "strict KEX violation: "
++				    "KEXINIT was not the first packet");
++		}
+ 	}
+ 
+ 	/* Algorithm Negotiation */
+diff --git a/kex.h b/kex.h
+index 938dca03b..c60e592ec 100644
+--- a/kex.h
++++ b/kex.h
+@@ -154,6 +154,7 @@ 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 00e3180cb..78c357b14 100644
+--- a/packet.c
++++ b/packet.c
+@@ -1208,8 +1208,13 @@ 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;
+@@ -1217,6 +1222,12 @@ 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("%s: resetting send seqnr %u", __func__,
++		    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)
+@@ -1350,8 +1361,7 @@ 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)
+@@ -1638,10 +1648,16 @@ 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;
+@@ -1707,6 +1723,11 @@ 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("%s: resetting read seqnr %u", __func__,
++		    state->p_read.seqnr);
++		state->p_read.seqnr = 0;
++	}
+ 
+ 	/* do we need to rekey? */
+ 	if (ssh_packet_need_rekeying(ssh, 0)) {
+@@ -1731,10 +1752,39 @@ 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");
+@@ -1749,19 +1799,6 @@ 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;
+@@ -2240,6 +2277,7 @@ 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 ||
+@@ -2402,6 +2440,7 @@ 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 ||
+@@ -2729,6 +2768,7 @@ sshpkt_disconnect(struct ssh *ssh, const char *fmt,...)
+ 	vsnprintf(buf, sizeof(buf), fmt, args);
+ 	va_end(args);
+ 
++	debug2("%s: sending SSH2_MSG_DISCONNECT: %s", __func__, 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 c47fc31a6..61392c934 100644
+--- a/sshconnect2.c
++++ b/sshconnect2.c
+@@ -233,7 +233,8 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
+ 		fatal("%s: kex_assemble_namelist", __func__);
+ 	free(all_key);
+ 
+-	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
++	if ((s = kex_names_cat(options.kex_algorithms,
++	    "ext-info-c,kex-strict-c-v00@openssh.com")) == NULL)
+ 		fatal("%s: kex_names_cat", __func__);
+ 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
+ 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+@@ -423,7 +424,6 @@ 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 *);
+@@ -546,7 +546,7 @@ 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);
+@@ -591,13 +591,6 @@ input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
+ 	return r;
+ }
+ 
+-/* ARGSUSED */
+-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)
+ {
+@@ -679,6 +672,7 @@ 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 --git a/sshd.c b/sshd.c
+index fb9b7b7fb..e894ad6f7 100644
+--- a/sshd.c
++++ b/sshd.c
+@@ -2405,10 +2405,13 @@ do_ssh2_kex(struct ssh *ssh)
+ {
+ 	char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
+ 	struct kex *kex;
++	char *s;
+ 	int r;
+ 
+-	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
+-	    options.kex_algorithms);
++	if ((s = kex_names_cat(options.kex_algorithms,
++	    "kex-strict-s-v00@openssh.com")) == NULL)
++		fatal("%s: kex_names_cat", __func__);
++	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
+ 	myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
+ 	    options.ciphers);
+ 	myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
+@@ -2517,6 +2520,7 @@ do_ssh2_kex(struct ssh *ssh)
+ 	    (r = ssh_packet_write_wait(ssh)) != 0)
+ 		fatal("%s: send test: %s", __func__, ssh_err(r));
+ #endif
++	free(s);
+ 	debug("KEX done");
+ }
+