Version in base suite: 8.4p1-5+deb11u2 Base version: openssh_8.4p1-5+deb11u2 Target version: openssh_8.4p1-5+deb11u3 Base file: /srv/ftp-master.debian.org/ftp/pool/main/o/openssh/openssh_8.4p1-5+deb11u2.dsc Target file: /srv/ftp-master.debian.org/policy/pool/main/o/openssh/openssh_8.4p1-5+deb11u3.dsc .git-dpm | 4 changelog | 29 ++ patches/CVE-2021-41617-1.patch | 35 +++ patches/CVE-2021-41617-2.patch | 26 ++ patches/CVE-2023-48795.patch | 460 +++++++++++++++++++++++++++++++++++++++++ patches/CVE-2023-51385.patch | 94 ++++++++ patches/series | 4 7 files changed, 650 insertions(+), 2 deletions(-) diff -Nru openssh-8.4p1/debian/.git-dpm openssh-8.4p1/debian/.git-dpm --- openssh-8.4p1/debian/.git-dpm 2023-09-23 22:13:51.000000000 +0000 +++ openssh-8.4p1/debian/.git-dpm 2023-12-21 16:09:21.000000000 +0000 @@ -1,6 +1,6 @@ # see git-dpm(1) from git-dpm package -fb685ebb9f8391ab2836715c9c347ee50a0c9f48 -fb685ebb9f8391ab2836715c9c347ee50a0c9f48 +2bea7434c9fad19f017846adad0e995d8da00642 +2bea7434c9fad19f017846adad0e995d8da00642 2b2c99658e3e8ed452e28f88f9cdbcdfb2a461cb 2b2c99658e3e8ed452e28f88f9cdbcdfb2a461cb openssh_8.4p1.orig.tar.gz diff -Nru openssh-8.4p1/debian/changelog openssh-8.4p1/debian/changelog --- openssh-8.4p1/debian/changelog 2023-09-23 22:13:51.000000000 +0000 +++ openssh-8.4p1/debian/changelog 2023-12-21 16:09:44.000000000 +0000 @@ -1,3 +1,32 @@ +openssh (1:8.4p1-5+deb11u3) bullseye-security; urgency=medium + + * Cherry-pick from upstream: + - [CVE-2021-41617]: sshd(8) from OpenSSH 6.2 through 8.7 failed to + correctly initialise supplemental groups when executing an + AuthorizedKeysCommand or AuthorizedPrincipalsCommand, where a + AuthorizedKeysCommandUser or AuthorizedPrincipalsCommandUser directive + has been set to run the command as a different user. Instead these + commands would inherit the groups that sshd(8) was started with + (closes: #995130). + - [CVE-2023-48795] ssh(1), sshd(8): implement protocol extensions to + thwart the so-called "Terrapin attack" discovered by Fabian Bäumer, + Marcus Brinkmann and Jörg Schwenk. This attack allows a MITM to effect + a limited break of the integrity of the early encrypted SSH transport + protocol by sending extra messages prior to the commencement of + encryption, and deleting an equal number of consecutive messages + immediately after encryption starts. A peer SSH client/server would + not be able to detect that messages were deleted. + - [CVE-2023-51385] ssh(1): if an invalid user or hostname that contained + shell metacharacters was passed to ssh(1), and a ProxyCommand, + LocalCommand directive or "match exec" predicate referenced the user + or hostname via %u, %h or similar expansion token, then an attacker + who could supply arbitrary user/hostnames to ssh(1) could potentially + perform command injection depending on what quoting was present in the + user-supplied ssh_config(5) directive. ssh(1) now bans most shell + metacharacters from user and hostnames supplied via the command-line. + + -- Colin Watson Thu, 21 Dec 2023 16:09:44 +0000 + openssh (1:8.4p1-5+deb11u2) bullseye; urgency=medium * Cherry-pick from OpenSSH 9.3p2: diff -Nru openssh-8.4p1/debian/patches/CVE-2021-41617-1.patch openssh-8.4p1/debian/patches/CVE-2021-41617-1.patch --- openssh-8.4p1/debian/patches/CVE-2021-41617-1.patch 1970-01-01 00:00:00.000000000 +0000 +++ openssh-8.4p1/debian/patches/CVE-2021-41617-1.patch 2023-12-21 16:09:21.000000000 +0000 @@ -0,0 +1,35 @@ +From ad2748dee50e4c0040f6efda5eff4a34e4eb5b85 Mon Sep 17 00:00:00 2001 +From: "djm@openbsd.org" +Date: Sun, 26 Sep 2021 14:01:03 +0000 +Subject: upstream: need initgroups() before setresgid(); reported by anton@, + +ok deraadt@ + +OpenBSD-Commit-ID: 6aa003ee658b316960d94078f2a16edbc25087ce + +Bug-Debian: https://bugs.debian.org/995130 +Origin: backport, https://anongit.mindrot.org/openssh.git/commit/?id=f3cbe43e28fe71427d41cfe3a17125b972710455 +Last-Update: 2023-12-19 + +Patch-Name: CVE-2021-41617-1.patch +--- + auth.c | 6 ++++++ + 1 file changed, 6 insertions(+) + +diff --git a/auth.c b/auth.c +index 4152d9c44..32870851b 100644 +--- a/auth.c ++++ b/auth.c +@@ -853,6 +853,12 @@ subprocess(const char *tag, struct passwd *pw, const char *command, + } + closefrom(STDERR_FILENO + 1); + ++ if (geteuid() == 0 && ++ initgroups(pw->pw_name, pw->pw_gid) == -1) { ++ error("%s: initgroups(%s, %u): %s", tag, ++ pw->pw_name, (u_int)pw->pw_gid, strerror(errno)); ++ _exit(1); ++ } + /* Don't use permanently_set_uid() here to avoid fatal() */ + if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) { + error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid, diff -Nru openssh-8.4p1/debian/patches/CVE-2021-41617-2.patch openssh-8.4p1/debian/patches/CVE-2021-41617-2.patch --- openssh-8.4p1/debian/patches/CVE-2021-41617-2.patch 1970-01-01 00:00:00.000000000 +0000 +++ openssh-8.4p1/debian/patches/CVE-2021-41617-2.patch 2023-12-21 16:09:21.000000000 +0000 @@ -0,0 +1,26 @@ +From 0afd6ea47554dee40d1eaf33fa73d693fb661e64 Mon Sep 17 00:00:00 2001 +From: Damien Miller +Date: Mon, 27 Sep 2021 00:03:19 +1000 +Subject: initgroups needs grp.h + +Bug-Debian: https://bugs.debian.org/995130 +Origin: backport, https://anongit.mindrot.org/openssh.git/commit/?id=bf944e3794eff5413f2df1ef37cddf96918c6bde +Last-Update: 2023-12-19 + +Patch-Name: CVE-2021-41617-2.patch +--- + auth.c | 1 + + 1 file changed, 1 insertion(+) + +diff --git a/auth.c b/auth.c +index 32870851b..88578ec45 100644 +--- a/auth.c ++++ b/auth.c +@@ -39,6 +39,7 @@ + # include + #endif + #include ++#include + #ifdef HAVE_LOGIN_H + #include + #endif diff -Nru openssh-8.4p1/debian/patches/CVE-2023-48795.patch openssh-8.4p1/debian/patches/CVE-2023-48795.patch --- openssh-8.4p1/debian/patches/CVE-2023-48795.patch 1970-01-01 00:00:00.000000000 +0000 +++ openssh-8.4p1/debian/patches/CVE-2023-48795.patch 2023-12-21 16:09:21.000000000 +0000 @@ -0,0 +1,460 @@ +From 802a7af111c9ddb438ca4fd8c5cc35534e199fda Mon Sep 17 00:00:00 2001 +From: "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"); + } + diff -Nru openssh-8.4p1/debian/patches/CVE-2023-51385.patch openssh-8.4p1/debian/patches/CVE-2023-51385.patch --- openssh-8.4p1/debian/patches/CVE-2023-51385.patch 1970-01-01 00:00:00.000000000 +0000 +++ openssh-8.4p1/debian/patches/CVE-2023-51385.patch 2023-12-21 16:09:21.000000000 +0000 @@ -0,0 +1,94 @@ +From 2bea7434c9fad19f017846adad0e995d8da00642 Mon Sep 17 00:00:00 2001 +From: "djm@openbsd.org" +Date: Mon, 18 Dec 2023 14:47:44 +0000 +Subject: upstream: ban user/hostnames with most shell metacharacters + +This makes ssh(1) refuse user or host names provided on the +commandline that contain most shell metacharacters. + +Some programs that invoke ssh(1) using untrusted data do not filter +metacharacters in arguments they supply. This could create +interactions with user-specified ProxyCommand and other directives +that allow shell injection attacks to occur. + +It's a mistake to invoke ssh(1) with arbitrary untrusted arguments, +but getting this stuff right can be tricky, so this should prevent +most obvious ways of creating risky situations. It however is not +and cannot be perfect: ssh(1) has no practical way of interpreting +what shell quoting rules are in use and how they interact with the +user's specified ProxyCommand. + +To allow configurations that use strange user or hostnames to +continue to work, this strictness is applied only to names coming +from the commandline. Names specified using User or Hostname +directives in ssh_config(5) are not affected. + +feedback/ok millert@ markus@ dtucker@ deraadt@ + +OpenBSD-Commit-ID: 3b487348b5964f3e77b6b4d3da4c3b439e94b2d9 + +Origin: backport, https://anongit.mindrot.org/openssh.git/commit/?id=7ef3787c84b6b524501211b11a26c742f829af1a +Last-Update: 2023-12-19 + +Patch-Name: CVE-2023-51385.patch +--- + ssh.c | 39 +++++++++++++++++++++++++++++++++++++++ + 1 file changed, 39 insertions(+) + +diff --git a/ssh.c b/ssh.c +index aa15b8a1f..dda3405c9 100644 +--- a/ssh.c ++++ b/ssh.c +@@ -638,6 +638,41 @@ set_addrinfo_port(struct addrinfo *addrs, int port) + } + } + ++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. + */ +@@ -1123,6 +1158,10 @@ 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"); + host_arg = xstrdup(host); + + /* Initialize the command to execute on remote host. */ diff -Nru openssh-8.4p1/debian/patches/series openssh-8.4p1/debian/patches/series --- openssh-8.4p1/debian/patches/series 2023-09-23 22:13:51.000000000 +0000 +++ openssh-8.4p1/debian/patches/series 2023-12-21 16:09:21.000000000 +0000 @@ -29,3 +29,7 @@ sandbox-pselect6_time64.patch CVE-2023-38408-1.patch CVE-2023-38408-2.patch +CVE-2021-41617-1.patch +CVE-2021-41617-2.patch +CVE-2023-48795.patch +CVE-2023-51385.patch