From f0c21dd4888ce63469595836390606ec24ac0119 Mon Sep 17 00:00:00 2001 From: Fabrice Fontaine Date: Mon, 1 Jan 2024 23:06:01 +0100 Subject: [PATCH] package/libssh2: fix CVE-2023-48795 https://github.com/advisories/GHSA-45x7-px36-x8w8 Signed-off-by: Fabrice Fontaine Signed-off-by: Thomas Petazzoni --- ...o-fix-CVE-2023-48795-Terrapin-Attack.patch | 462 ++++++++++++++++++ package/libssh2/libssh2.mk | 3 + 2 files changed, 465 insertions(+) create mode 100644 package/libssh2/0002-src-add-strict-KEX-to-fix-CVE-2023-48795-Terrapin-Attack.patch diff --git a/package/libssh2/0002-src-add-strict-KEX-to-fix-CVE-2023-48795-Terrapin-Attack.patch b/package/libssh2/0002-src-add-strict-KEX-to-fix-CVE-2023-48795-Terrapin-Attack.patch new file mode 100644 index 0000000000..2ccedee19e --- /dev/null +++ b/package/libssh2/0002-src-add-strict-KEX-to-fix-CVE-2023-48795-Terrapin-Attack.patch @@ -0,0 +1,462 @@ +From d34d9258b8420b19ec3f97b4cc5bf7aa7d98e35a Mon Sep 17 00:00:00 2001 +From: Michael Buckley +Date: Thu, 30 Nov 2023 15:08:02 -0800 +Subject: [PATCH] src: add 'strict KEX' to fix CVE-2023-48795 "Terrapin Attack" + +Refs: +https://terrapin-attack.com/ +https://seclists.org/oss-sec/2023/q4/292 +https://osv.dev/list?ecosystem=&q=CVE-2023-48795 +https://github.com/advisories/GHSA-45x7-px36-x8w8 +https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-48795 + +Fixes #1290 +Closes #1291 + +Upstream: https://github.com/libssh2/libssh2/commit/d34d9258b8420b19ec3f97b4cc5bf7aa7d98e35a +Signed-off-by: Fabrice Fontaine +--- + src/kex.c | 63 +++++++++++++++++++++++------------ + src/libssh2_priv.h | 18 +++++++--- + src/packet.c | 83 +++++++++++++++++++++++++++++++++++++++++++--- + src/packet.h | 2 +- + src/session.c | 3 ++ + src/transport.c | 12 ++++++- + 6 files changed, 149 insertions(+), 32 deletions(-) + +diff --git a/src/kex.c b/src/kex.c +index 8e7b7f0af3..a7b301e157 100644 +--- a/src/kex.c ++++ b/src/kex.c +@@ -3032,6 +3032,13 @@ kex_method_extension_negotiation = { + 0, + }; + ++static const LIBSSH2_KEX_METHOD ++kex_method_strict_client_extension = { ++ "kex-strict-c-v00@openssh.com", ++ NULL, ++ 0, ++}; ++ + static const LIBSSH2_KEX_METHOD *libssh2_kex_methods[] = { + #if LIBSSH2_ED25519 + &kex_method_ssh_curve25519_sha256, +@@ -3050,6 +3057,7 @@ static const LIBSSH2_KEX_METHOD *libssh2_kex_methods[] = { + &kex_method_diffie_helman_group1_sha1, + &kex_method_diffie_helman_group_exchange_sha1, + &kex_method_extension_negotiation, ++ &kex_method_strict_client_extension, + NULL + }; + +@@ -3302,13 +3310,13 @@ static int kexinit(LIBSSH2_SESSION * session) + return 0; + } + +-/* kex_agree_instr ++/* _libssh2_kex_agree_instr + * Kex specific variant of strstr() + * Needle must be preceded by BOL or ',', and followed by ',' or EOL + */ +-static unsigned char * +-kex_agree_instr(unsigned char *haystack, size_t haystack_len, +- const unsigned char *needle, size_t needle_len) ++unsigned char * ++_libssh2_kex_agree_instr(unsigned char *haystack, size_t haystack_len, ++ const unsigned char *needle, size_t needle_len) + { + unsigned char *s; + unsigned char *end_haystack; +@@ -3393,7 +3401,7 @@ static int kex_agree_hostkey(LIBSSH2_SESSION * session, + while(s && *s) { + unsigned char *p = (unsigned char *) strchr((char *) s, ','); + size_t method_len = (p ? (size_t)(p - s) : strlen((char *) s)); +- if(kex_agree_instr(hostkey, hostkey_len, s, method_len)) { ++ if(_libssh2_kex_agree_instr(hostkey, hostkey_len, s, method_len)) { + const LIBSSH2_HOSTKEY_METHOD *method = + (const LIBSSH2_HOSTKEY_METHOD *) + kex_get_method_by_name((char *) s, method_len, +@@ -3427,9 +3435,9 @@ static int kex_agree_hostkey(LIBSSH2_SESSION * session, + } + + while(hostkeyp && (*hostkeyp) && (*hostkeyp)->name) { +- s = kex_agree_instr(hostkey, hostkey_len, +- (unsigned char *) (*hostkeyp)->name, +- strlen((*hostkeyp)->name)); ++ s = _libssh2_kex_agree_instr(hostkey, hostkey_len, ++ (unsigned char *) (*hostkeyp)->name, ++ strlen((*hostkeyp)->name)); + if(s) { + /* So far so good, but does it suit our purposes? (Encrypting vs + Signing) */ +@@ -3463,6 +3471,12 @@ static int kex_agree_kex_hostkey(LIBSSH2_SESSION * session, unsigned char *kex, + { + const LIBSSH2_KEX_METHOD **kexp = libssh2_kex_methods; + unsigned char *s; ++ const unsigned char *strict = ++ (unsigned char *)"kex-strict-s-v00@openssh.com"; ++ ++ if(_libssh2_kex_agree_instr(kex, kex_len, strict, 28)) { ++ session->kex_strict = 1; ++ } + + if(session->kex_prefs) { + s = (unsigned char *) session->kex_prefs; +@@ -3470,7 +3484,7 @@ static int kex_agree_kex_hostkey(LIBSSH2_SESSION * session, unsigned char *kex, + while(s && *s) { + unsigned char *q, *p = (unsigned char *) strchr((char *) s, ','); + size_t method_len = (p ? (size_t)(p - s) : strlen((char *) s)); +- q = kex_agree_instr(kex, kex_len, s, method_len); ++ q = _libssh2_kex_agree_instr(kex, kex_len, s, method_len); + if(q) { + const LIBSSH2_KEX_METHOD *method = (const LIBSSH2_KEX_METHOD *) + kex_get_method_by_name((char *) s, method_len, +@@ -3504,9 +3518,9 @@ static int kex_agree_kex_hostkey(LIBSSH2_SESSION * session, unsigned char *kex, + } + + while(*kexp && (*kexp)->name) { +- s = kex_agree_instr(kex, kex_len, +- (unsigned char *) (*kexp)->name, +- strlen((*kexp)->name)); ++ s = _libssh2_kex_agree_instr(kex, kex_len, ++ (unsigned char *) (*kexp)->name, ++ strlen((*kexp)->name)); + if(s) { + /* We've agreed on a key exchange method, + * Can we agree on a hostkey that works with this kex? +@@ -3550,7 +3564,7 @@ static int kex_agree_crypt(LIBSSH2_SESSION * session, + unsigned char *p = (unsigned char *) strchr((char *) s, ','); + size_t method_len = (p ? (size_t)(p - s) : strlen((char *) s)); + +- if(kex_agree_instr(crypt, crypt_len, s, method_len)) { ++ if(_libssh2_kex_agree_instr(crypt, crypt_len, s, method_len)) { + const LIBSSH2_CRYPT_METHOD *method = + (const LIBSSH2_CRYPT_METHOD *) + kex_get_method_by_name((char *) s, method_len, +@@ -3572,9 +3586,9 @@ static int kex_agree_crypt(LIBSSH2_SESSION * session, + } + + while(*cryptp && (*cryptp)->name) { +- s = kex_agree_instr(crypt, crypt_len, +- (unsigned char *) (*cryptp)->name, +- strlen((*cryptp)->name)); ++ s = _libssh2_kex_agree_instr(crypt, crypt_len, ++ (unsigned char *) (*cryptp)->name, ++ strlen((*cryptp)->name)); + if(s) { + endpoint->crypt = *cryptp; + return 0; +@@ -3614,7 +3628,7 @@ static int kex_agree_mac(LIBSSH2_SESSION * session, + unsigned char *p = (unsigned char *) strchr((char *) s, ','); + size_t method_len = (p ? (size_t)(p - s) : strlen((char *) s)); + +- if(kex_agree_instr(mac, mac_len, s, method_len)) { ++ if(_libssh2_kex_agree_instr(mac, mac_len, s, method_len)) { + const LIBSSH2_MAC_METHOD *method = (const LIBSSH2_MAC_METHOD *) + kex_get_method_by_name((char *) s, method_len, + (const LIBSSH2_COMMON_METHOD **) +@@ -3635,8 +3649,9 @@ static int kex_agree_mac(LIBSSH2_SESSION * session, + } + + while(*macp && (*macp)->name) { +- s = kex_agree_instr(mac, mac_len, (unsigned char *) (*macp)->name, +- strlen((*macp)->name)); ++ s = _libssh2_kex_agree_instr(mac, mac_len, ++ (unsigned char *) (*macp)->name, ++ strlen((*macp)->name)); + if(s) { + endpoint->mac = *macp; + return 0; +@@ -3667,7 +3682,7 @@ static int kex_agree_comp(LIBSSH2_SESSION *session, + unsigned char *p = (unsigned char *) strchr((char *) s, ','); + size_t method_len = (p ? (size_t)(p - s) : strlen((char *) s)); + +- if(kex_agree_instr(comp, comp_len, s, method_len)) { ++ if(_libssh2_kex_agree_instr(comp, comp_len, s, method_len)) { + const LIBSSH2_COMP_METHOD *method = + (const LIBSSH2_COMP_METHOD *) + kex_get_method_by_name((char *) s, method_len, +@@ -3689,8 +3704,9 @@ static int kex_agree_comp(LIBSSH2_SESSION *session, + } + + while(*compp && (*compp)->name) { +- s = kex_agree_instr(comp, comp_len, (unsigned char *) (*compp)->name, +- strlen((*compp)->name)); ++ s = _libssh2_kex_agree_instr(comp, comp_len, ++ (unsigned char *) (*compp)->name, ++ strlen((*compp)->name)); + if(s) { + endpoint->comp = *compp; + return 0; +@@ -3871,6 +3887,7 @@ _libssh2_kex_exchange(LIBSSH2_SESSION * session, int reexchange, + session->local.kexinit = key_state->oldlocal; + session->local.kexinit_len = key_state->oldlocal_len; + key_state->state = libssh2_NB_state_idle; ++ session->state &= ~LIBSSH2_STATE_INITIAL_KEX; + session->state &= ~LIBSSH2_STATE_KEX_ACTIVE; + session->state &= ~LIBSSH2_STATE_EXCHANGING_KEYS; + return -1; +@@ -3896,6 +3913,7 @@ _libssh2_kex_exchange(LIBSSH2_SESSION * session, int reexchange, + session->local.kexinit = key_state->oldlocal; + session->local.kexinit_len = key_state->oldlocal_len; + key_state->state = libssh2_NB_state_idle; ++ session->state &= ~LIBSSH2_STATE_INITIAL_KEX; + session->state &= ~LIBSSH2_STATE_KEX_ACTIVE; + session->state &= ~LIBSSH2_STATE_EXCHANGING_KEYS; + return -1; +@@ -3944,6 +3962,7 @@ _libssh2_kex_exchange(LIBSSH2_SESSION * session, int reexchange, + session->remote.kexinit = NULL; + } + ++ session->state &= ~LIBSSH2_STATE_INITIAL_KEX; + session->state &= ~LIBSSH2_STATE_KEX_ACTIVE; + session->state &= ~LIBSSH2_STATE_EXCHANGING_KEYS; + +diff --git a/src/libssh2_priv.h b/src/libssh2_priv.h +index 7660366954..18d9ab2130 100644 +--- a/src/libssh2_priv.h ++++ b/src/libssh2_priv.h +@@ -736,6 +736,9 @@ struct _LIBSSH2_SESSION + /* key signing algorithm preferences -- NULL yields server order */ + char *sign_algo_prefs; + ++ /* Whether to use the OpenSSH Strict KEX extension */ ++ int kex_strict; ++ + /* (remote as source of data -- packet_read ) */ + libssh2_endpoint_data remote; + +@@ -908,6 +911,7 @@ struct _LIBSSH2_SESSION + int fullpacket_macstate; + size_t fullpacket_payload_len; + int fullpacket_packet_type; ++ uint32_t fullpacket_required_type; + + /* State variables used in libssh2_sftp_init() */ + libssh2_nonblocking_states sftpInit_state; +@@ -948,10 +952,11 @@ struct _LIBSSH2_SESSION + }; + + /* session.state bits */ +-#define LIBSSH2_STATE_EXCHANGING_KEYS 0x00000001 +-#define LIBSSH2_STATE_NEWKEYS 0x00000002 +-#define LIBSSH2_STATE_AUTHENTICATED 0x00000004 +-#define LIBSSH2_STATE_KEX_ACTIVE 0x00000008 ++#define LIBSSH2_STATE_INITIAL_KEX 0x00000001 ++#define LIBSSH2_STATE_EXCHANGING_KEYS 0x00000002 ++#define LIBSSH2_STATE_NEWKEYS 0x00000004 ++#define LIBSSH2_STATE_AUTHENTICATED 0x00000008 ++#define LIBSSH2_STATE_KEX_ACTIVE 0x00000010 + + /* session.flag helpers */ + #ifdef MSG_NOSIGNAL +@@ -1182,6 +1187,11 @@ ssize_t _libssh2_send(libssh2_socket_t socket, const void *buffer, + int _libssh2_kex_exchange(LIBSSH2_SESSION * session, int reexchange, + key_exchange_state_t * state); + ++unsigned char *_libssh2_kex_agree_instr(unsigned char *haystack, ++ size_t haystack_len, ++ const unsigned char *needle, ++ size_t needle_len); ++ + /* Let crypt.c/hostkey.c expose their method structs */ + const LIBSSH2_CRYPT_METHOD **libssh2_crypt_methods(void); + const LIBSSH2_HOSTKEY_METHOD **libssh2_hostkey_methods(void); +diff --git a/src/packet.c b/src/packet.c +index eccb8c56a8..6da14e9fa1 100644 +--- a/src/packet.c ++++ b/src/packet.c +@@ -624,14 +624,13 @@ packet_authagent_open(LIBSSH2_SESSION * session, + * layer when it has received a packet. + * + * The input pointer 'data' is pointing to allocated data that this function +- * is asked to deal with so on failure OR success, it must be freed fine. +- * The only exception is when the return code is LIBSSH2_ERROR_EAGAIN. ++ * will be freed unless return the code is LIBSSH2_ERROR_EAGAIN. + * + * This function will always be called with 'datalen' greater than zero. + */ + int + _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, +- size_t datalen, int macstate) ++ size_t datalen, int macstate, uint32_t seq) + { + int rc = 0; + unsigned char *message = NULL; +@@ -676,6 +675,70 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, + break; + } + ++ if(session->state & LIBSSH2_STATE_INITIAL_KEX) { ++ if(msg == SSH_MSG_KEXINIT) { ++ if(!session->kex_strict) { ++ if(datalen < 17) { ++ LIBSSH2_FREE(session, data); ++ session->packAdd_state = libssh2_NB_state_idle; ++ return _libssh2_error(session, ++ LIBSSH2_ERROR_BUFFER_TOO_SMALL, ++ "Data too short extracting kex"); ++ } ++ else { ++ const unsigned char *strict = ++ (unsigned char *)"kex-strict-s-v00@openssh.com"; ++ struct string_buf buf; ++ unsigned char *algs = NULL; ++ size_t algs_len = 0; ++ ++ buf.data = (unsigned char *)data; ++ buf.dataptr = buf.data; ++ buf.len = datalen; ++ buf.dataptr += 17; /* advance past type and cookie */ ++ ++ if(_libssh2_get_string(&buf, &algs, &algs_len)) { ++ LIBSSH2_FREE(session, data); ++ session->packAdd_state = libssh2_NB_state_idle; ++ return _libssh2_error(session, ++ LIBSSH2_ERROR_BUFFER_TOO_SMALL, ++ "Algs too short"); ++ } ++ ++ if(algs_len == 0 || ++ _libssh2_kex_agree_instr(algs, algs_len, strict, 28)) { ++ session->kex_strict = 1; ++ } ++ } ++ } ++ ++ if(session->kex_strict && seq) { ++ LIBSSH2_FREE(session, data); ++ session->socket_state = LIBSSH2_SOCKET_DISCONNECTED; ++ session->packAdd_state = libssh2_NB_state_idle; ++ libssh2_session_disconnect(session, "strict KEX violation: " ++ "KEXINIT was not the first packet"); ++ ++ return _libssh2_error(session, LIBSSH2_ERROR_SOCKET_DISCONNECT, ++ "strict KEX violation: " ++ "KEXINIT was not the first packet"); ++ } ++ } ++ ++ if(session->kex_strict && session->fullpacket_required_type && ++ session->fullpacket_required_type != msg) { ++ LIBSSH2_FREE(session, data); ++ session->socket_state = LIBSSH2_SOCKET_DISCONNECTED; ++ session->packAdd_state = libssh2_NB_state_idle; ++ libssh2_session_disconnect(session, "strict KEX violation: " ++ "unexpected packet type"); ++ ++ return _libssh2_error(session, LIBSSH2_ERROR_SOCKET_DISCONNECT, ++ "strict KEX violation: " ++ "unexpected packet type"); ++ } ++ } ++ + if(session->packAdd_state == libssh2_NB_state_allocated) { + /* A couple exceptions to the packet adding rule: */ + switch(msg) { +@@ -1364,6 +1427,15 @@ _libssh2_packet_ask(LIBSSH2_SESSION * session, unsigned char packet_type, + + return 0; + } ++ else if(session->kex_strict && ++ (session->state & LIBSSH2_STATE_INITIAL_KEX)) { ++ libssh2_session_disconnect(session, "strict KEX violation: " ++ "unexpected packet type"); ++ ++ return _libssh2_error(session, LIBSSH2_ERROR_SOCKET_DISCONNECT, ++ "strict KEX violation: " ++ "unexpected packet type"); ++ } + packet = _libssh2_list_next(&packet->node); + } + return -1; +@@ -1425,7 +1497,10 @@ _libssh2_packet_require(LIBSSH2_SESSION * session, unsigned char packet_type, + } + + while(session->socket_state == LIBSSH2_SOCKET_CONNECTED) { +- int ret = _libssh2_transport_read(session); ++ int ret; ++ session->fullpacket_required_type = packet_type; ++ ret = _libssh2_transport_read(session); ++ session->fullpacket_required_type = 0; + if(ret == LIBSSH2_ERROR_EAGAIN) + return ret; + else if(ret < 0) { +diff --git a/src/packet.h b/src/packet.h +index 1d90b8af12..955351e5f6 100644 +--- a/src/packet.h ++++ b/src/packet.h +@@ -72,6 +72,6 @@ int _libssh2_packet_burn(LIBSSH2_SESSION * session, + int _libssh2_packet_write(LIBSSH2_SESSION * session, unsigned char *data, + unsigned long data_len); + int _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, +- size_t datalen, int macstate); ++ size_t datalen, int macstate, uint32_t seq); + + #endif /* LIBSSH2_PACKET_H */ +diff --git a/src/session.c b/src/session.c +index 35e7929fe7..9d89ade8ec 100644 +--- a/src/session.c ++++ b/src/session.c +@@ -469,6 +469,8 @@ libssh2_session_init_ex(LIBSSH2_ALLOC_FUNC((*my_alloc)), + session->abstract = abstract; + session->api_timeout = 0; /* timeout-free API by default */ + session->api_block_mode = 1; /* blocking API by default */ ++ session->state = LIBSSH2_STATE_INITIAL_KEX; ++ session->fullpacket_required_type = 0; + session->packet_read_timeout = LIBSSH2_DEFAULT_READ_TIMEOUT; + session->flag.quote_paths = 1; /* default behavior is to quote paths + for the scp subsystem */ +@@ -1223,6 +1225,7 @@ libssh2_session_disconnect_ex(LIBSSH2_SESSION *session, int reason, + const char *desc, const char *lang) + { + int rc; ++ session->state &= ~LIBSSH2_STATE_INITIAL_KEX; + session->state &= ~LIBSSH2_STATE_EXCHANGING_KEYS; + BLOCK_ADJUST(rc, session, + session_disconnect(session, reason, desc, lang)); +diff --git a/src/transport.c b/src/transport.c +index 21be9d2b80..a8bb588a4b 100644 +--- a/src/transport.c ++++ b/src/transport.c +@@ -186,6 +186,7 @@ fullpacket(LIBSSH2_SESSION * session, int encrypted /* 1 or 0 */ ) + struct transportpacket *p = &session->packet; + int rc; + int compressed; ++ uint32_t seq = session->remote.seqno; + + if(session->fullpacket_state == libssh2_NB_state_idle) { + session->fullpacket_macstate = LIBSSH2_MAC_CONFIRMED; +@@ -317,7 +318,7 @@ fullpacket(LIBSSH2_SESSION * session, int encrypted /* 1 or 0 */ ) + if(session->fullpacket_state == libssh2_NB_state_created) { + rc = _libssh2_packet_add(session, p->payload, + session->fullpacket_payload_len, +- session->fullpacket_macstate); ++ session->fullpacket_macstate, seq); + if(rc == LIBSSH2_ERROR_EAGAIN) + return rc; + if(rc) { +@@ -328,6 +329,11 @@ fullpacket(LIBSSH2_SESSION * session, int encrypted /* 1 or 0 */ ) + + session->fullpacket_state = libssh2_NB_state_idle; + ++ if(session->kex_strict && ++ session->fullpacket_packet_type == SSH_MSG_NEWKEYS) { ++ session->remote.seqno = 0; ++ } ++ + return session->fullpacket_packet_type; + } + +@@ -1093,6 +1099,10 @@ int _libssh2_transport_send(LIBSSH2_SESSION *session, + + session->local.seqno++; + ++ if(session->kex_strict && data[0] == SSH_MSG_NEWKEYS) { ++ session->local.seqno = 0; ++ } ++ + ret = LIBSSH2_SEND(session, p->outbuf, total_length, + LIBSSH2_SOCKET_SEND_FLAGS(session)); + if(ret < 0) diff --git a/package/libssh2/libssh2.mk b/package/libssh2/libssh2.mk index a42be46a7a..b2c07cbf30 100644 --- a/package/libssh2/libssh2.mk +++ b/package/libssh2/libssh2.mk @@ -13,6 +13,9 @@ LIBSSH2_CPE_ID_VENDOR = libssh2 LIBSSH2_INSTALL_STAGING = YES LIBSSH2_CONF_OPTS = --disable-examples-build --disable-rpath +# 0002-src-add-strict-KEX-to-fix-CVE-2023-48795-Terrapin-Attack.patch +LIBSSH2_IGNORE_CVES += CVE-2023-48795 + ifeq ($(BR2_PACKAGE_LIBSSH2_MBEDTLS),y) LIBSSH2_DEPENDENCIES += mbedtls LIBSSH2_CONF_OPTS += --with-libmbedcrypto-prefix=$(STAGING_DIR)/usr \