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File _service:tar_scm_kernel_repo:backport-RSA-SHA2-256-512-key-upgrade-support-RFC-8332.patch of Package libssh2
From 64a555d6f5aafed504a10e5b756e85c91b1d56ce Mon Sep 17 00:00:00 2001 From: Will Cosgrove <will@panic.com> Date: Thu, 6 Jan 2022 09:50:58 -0800 Subject: [PATCH] RSA SHA2 256/512 key upgrade support RFC 8332 #536 (#626) Notes: * Host Key RSA 256/512 support #536 * Client side key hash upgrading for RFC 8332 * Support for server-sig-algs, ext-info-c server messages * Customizing preferred server-sig-algs via the preference LIBSSH2_METHOD_SIGN_ALGO Credit: Anders Borum, Will Cosgrove --- docs/HACKING-CRYPTO | 37 ++++++++ docs/libssh2_session_methods.3 | 7 +- include/libssh2.h | 1 + src/crypto.h | 32 +++++++ src/hostkey.c | 198 ++++++++++++++++++++++++++++++++++++++++- src/kex.c | 22 +++++ src/libgcrypt.c | 18 ++++ src/libgcrypt.h | 1 + src/libssh2_priv.h | 8 ++ src/mbedtls.c | 19 ++++ src/mbedtls.h | 1 + src/openssl.c | 94 +++++++++++++++++-- src/openssl.h | 2 + src/packet.c | 69 ++++++++++++++ src/userauth.c | 159 +++++++++++++++++++++++++++++++-- src/wincng.c | 18 ++++ src/wincng.h | 1 + 19 files changed, 685 insertions(+), 21 deletions(-) diff --git a/docs/HACKING-CRYPTO b/docs/HACKING-CRYPTO index ca94772..85d813a 100644 --- a/docs/HACKING-CRYPTO +++ b/docs/HACKING-CRYPTO @@ -637,6 +637,32 @@ Note: this procedure is not used if macro _libssh2_rsa_sha1_signv() is defined. void _libssh2_rsa_free(libssh2_rsa_ctx *rsactx); Releases the RSA computation context at rsactx. +LIBSSH2_RSA_SHA2 +#define as 1 if the crypto library supports RSA SHA2 256/512, else 0. +If defined as 0, the rest of this section can be omitted. + +int _libssh2_rsa_sha2_sign(LIBSSH2_SESSION * session, + libssh2_rsa_ctx * rsactx, + const unsigned char *hash, + size_t hash_len, + unsigned char **signature, + size_t *signature_len); +RSA signs the (hash, hashlen) SHA-2 hash bytes based on hash length and stores +the allocated signature at (signature, signature_len). +Signature buffer must be allocated from the given session. +Returns 0 if OK, else -1. +This procedure is already prototyped in crypto.h. +Note: this procedure is not used if macro _libssh2_rsa_sha1_signv() is defined. + +int _libssh2_rsa_sha2_verify(libssh2_rsa_ctx * rsa, + size_t hash_len, + const unsigned char *sig, + unsigned long sig_len, + const unsigned char *m, unsigned long m_len); +Verify (sig, sig_len) signature of (m, m_len) using an SHA-2 hash based on +hash length and the RSA context. +Return 0 if OK, else -1. +This procedure is already prototyped in crypto.h. 7.2) DSA LIBSSH2_DSA @@ -900,3 +926,14 @@ If this is not needed, it should be defined as an empty macro. int _libssh2_random(unsigned char *buf, int len); Store len random bytes at buf. Returns 0 if OK, else -1. + +const char * _libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len); + +This function is for implementing key hash upgrading as defined in RFC 8332. + +Based on the incoming key_method value, this function will return a +list of supported algorithms that can upgrade the original key method algorithm +as a comma seperated list, if there is no upgrade option this function should +return NULL. diff --git a/docs/libssh2_session_methods.3 b/docs/libssh2_session_methods.3 index cc4f6d4..0e7f79f 100644 --- a/docs/libssh2_session_methods.3 +++ b/docs/libssh2_session_methods.3 @@ -1,4 +1,4 @@ -.TH libssh2_session_methods 3 "1 Jun 2007" "libssh2 0.15" "libssh2 manual" +.TH libssh2_session_methods 3 "8 Nov 2021" "libssh2 1.11" "libssh2 manual" .SH NAME libssh2_session_methods - return the currently active algorithms .SH SYNOPSIS @@ -8,13 +8,14 @@ const char * libssh2_session_methods(LIBSSH2_SESSION *session, int method_type); .SH DESCRIPTION -\fIsession\fP - Session instance as returned by +\fIsession\fP - Session instance as returned by .BR libssh2_session_init_ex(3) \fImethod_type\fP - one of the method type constants: LIBSSH2_METHOD_KEX, LIBSSH2_METHOD_HOSTKEY, LIBSSH2_METHOD_CRYPT_CS, LIBSSH2_METHOD_CRYPT_SC, LIBSSH2_METHOD_MAC_CS, LIBSSH2_METHOD_MAC_SC, LIBSSH2_METHOD_COMP_CS, -LIBSSH2_METHOD_COMP_SC, LIBSSH2_METHOD_LANG_CS, LIBSSH2_METHOD_LANG_SC. +LIBSSH2_METHOD_COMP_SC, LIBSSH2_METHOD_LANG_CS, LIBSSH2_METHOD_LANG_SC, +LIBSSH2_METHOD_SIGN_ALGO. Returns the actual method negotiated for a particular transport parameter. .SH RETURN VALUE diff --git a/include/libssh2.h b/include/libssh2.h index d064b31..b9ae809 100644 --- a/include/libssh2.h +++ b/include/libssh2.h @@ -356,6 +356,7 @@ typedef struct _LIBSSH2_USERAUTH_KBDINT_RESPONSE #define LIBSSH2_METHOD_COMP_SC 7 #define LIBSSH2_METHOD_LANG_CS 8 #define LIBSSH2_METHOD_LANG_SC 9 +#define LIBSSH2_METHOD_SIGN_ALGO 10 /* flags */ #define LIBSSH2_FLAG_SIGPIPE 1 diff --git a/src/crypto.h b/src/crypto.h index f512d60..809aef7 100644 --- a/src/crypto.h +++ b/src/crypto.h @@ -93,6 +93,19 @@ int _libssh2_rsa_sha1_sign(LIBSSH2_SESSION * session, size_t hash_len, unsigned char **signature, size_t *signature_len); +#if LIBSSH2_RSA_SHA2 +int _libssh2_rsa_sha2_sign(LIBSSH2_SESSION * session, + libssh2_rsa_ctx * rsactx, + const unsigned char *hash, + size_t hash_len, + unsigned char **signature, + size_t *signature_len); +int _libssh2_rsa_sha2_verify(libssh2_rsa_ctx * rsa, + size_t hash_len, + const unsigned char *sig, + unsigned long sig_len, + const unsigned char *m, unsigned long m_len); +#endif int _libssh2_rsa_new_private_frommemory(libssh2_rsa_ctx ** rsa, LIBSSH2_SESSION * session, const char *filedata, @@ -245,4 +258,23 @@ int _libssh2_pub_priv_keyfilememory(LIBSSH2_SESSION *session, size_t privatekeydata_len, const char *passphrase); + +/** + * @function _libssh2_supported_key_sign_algorithms + * @abstract Returns supported algorithms used for upgrading public + * key signing RFC 8332 + * @discussion Based on the incoming key_method value, this function + * will return supported algorithms that can upgrade the key method + * @related _libssh2_key_sign_algorithm() + * @param key_method current key method, usually the default key sig method + * @param key_method_len length of the key method buffer + * @result comma seperated list of supported upgrade options per RFC 8332, if + * there is no upgrade option return NULL + */ + +const char * +_libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len); + #endif /* __LIBSSH2_CRYPTO_H */ diff --git a/src/hostkey.c b/src/hostkey.c index c0e2c63..f005d90 100644 --- a/src/hostkey.c +++ b/src/hostkey.c @@ -64,8 +64,8 @@ hostkey_method_ssh_rsa_init(LIBSSH2_SESSION * session, void **abstract) { libssh2_rsa_ctx *rsactx; - unsigned char *e, *n; - size_t e_len, n_len; + unsigned char *e, *n, *type; + size_t e_len, n_len, type_len; struct string_buf buf; if(*abstract) { @@ -83,8 +83,27 @@ hostkey_method_ssh_rsa_init(LIBSSH2_SESSION * session, buf.dataptr = buf.data; buf.len = hostkey_data_len; - if(_libssh2_match_string(&buf, "ssh-rsa")) + if(_libssh2_get_string(&buf, &type, &type_len)) { return -1; + } + + /* we accept one of 3 header types */ + if(type_len == 7 && strncmp("ssh-rsa", (char *)type, 7) == 0) { + /* ssh-rsa */ + } +#if LIBSSH2_RSA_SHA2 + else if(type_len == 12 && strncmp("rsa-sha2-256", (char *)type, 12) == 0) { + /* rsa-sha2-256 */ + } + else if(type_len == 12 && strncmp("rsa-sha2-512", (char *)type, 12) == 0) { + /* rsa-sha2-512 */ + } +#endif + else { + _libssh2_debug(session, LIBSSH2_TRACE_ERROR, + "unexpected rsa type: %.*s", type_len, type); + return -1; + } if(_libssh2_get_string(&buf, &e, &e_len)) return -1; @@ -228,6 +247,146 @@ hostkey_method_ssh_rsa_signv(LIBSSH2_SESSION * session, } /* + * hostkey_method_ssh_rsa_sha2_256_sig_verify + * + * Verify signature created by remote + */ +#if LIBSSH2_RSA_SHA2 + +static int +hostkey_method_ssh_rsa_sha2_256_sig_verify(LIBSSH2_SESSION * session, + const unsigned char *sig, + size_t sig_len, + const unsigned char *m, + size_t m_len, void **abstract) +{ + libssh2_rsa_ctx *rsactx = (libssh2_rsa_ctx *) (*abstract); + (void) session; + + /* Skip past keyname_len(4) + keyname(12){"rsa-sha2-256"} + + signature_len(4) */ + if(sig_len < 20) + return -1; + + sig += 20; + sig_len -= 20; + return _libssh2_rsa_sha2_verify(rsactx, SHA256_DIGEST_LENGTH, sig, sig_len, + m, m_len); +} + +/* + * hostkey_method_ssh_rsa_sha2_256_signv + * + * Construct a signature from an array of vectors + */ + +static int +hostkey_method_ssh_rsa_sha2_256_signv(LIBSSH2_SESSION * session, + unsigned char **signature, + size_t *signature_len, + int veccount, + const struct iovec datavec[], + void **abstract) +{ + libssh2_rsa_ctx *rsactx = (libssh2_rsa_ctx *) (*abstract); + +#ifdef _libssh2_rsa_sha2_256_signv + return _libssh2_rsa_sha2_256_signv(session, signature, signature_len, + veccount, datavec, rsactx); +#else + int ret; + int i; + unsigned char hash[SHA256_DIGEST_LENGTH]; + libssh2_sha256_ctx ctx; + + libssh2_sha256_init(&ctx); + for(i = 0; i < veccount; i++) { + libssh2_sha256_update(ctx, datavec[i].iov_base, datavec[i].iov_len); + } + libssh2_sha256_final(ctx, hash); + + ret = _libssh2_rsa_sha2_sign(session, rsactx, hash, SHA256_DIGEST_LENGTH, + signature, signature_len); + if(ret) { + return -1; + } + + return 0; +#endif +} + +/* + * hostkey_method_ssh_rsa_sha2_512_sig_verify + * + * Verify signature created by remote + */ + +static int +hostkey_method_ssh_rsa_sha2_512_sig_verify(LIBSSH2_SESSION * session, + const unsigned char *sig, + size_t sig_len, + const unsigned char *m, + size_t m_len, void **abstract) +{ + libssh2_rsa_ctx *rsactx = (libssh2_rsa_ctx *) (*abstract); + (void) session; + + /* Skip past keyname_len(4) + keyname(12){"rsa-sha2-512"} + + signature_len(4) */ + if(sig_len < 20) + return -1; + + sig += 20; + sig_len -= 20; + return _libssh2_rsa_sha2_verify(rsactx, SHA512_DIGEST_LENGTH, sig, + sig_len, m, m_len); +} + + +/* + * hostkey_method_ssh_rsa_sha2_512_signv + * + * Construct a signature from an array of vectors + */ +static int +hostkey_method_ssh_rsa_sha2_512_signv(LIBSSH2_SESSION * session, + unsigned char **signature, + size_t *signature_len, + int veccount, + const struct iovec datavec[], + void **abstract) +{ + libssh2_rsa_ctx *rsactx = (libssh2_rsa_ctx *) (*abstract); + +#ifdef _libssh2_rsa_sha2_512_signv + return _libssh2_rsa_sha2_512_signv(session, signature, signature_len, + veccount, datavec, rsactx); +#else + int ret; + int i; + unsigned char hash[SHA512_DIGEST_LENGTH]; + libssh2_sha512_ctx ctx; + + libssh2_sha512_init(&ctx); + for(i = 0; i < veccount; i++) { + libssh2_sha512_update(ctx, datavec[i].iov_base, datavec[i].iov_len); + } + libssh2_sha512_final(ctx, hash); + + ret = _libssh2_rsa_sha2_sign(session, rsactx, hash, SHA512_DIGEST_LENGTH, + signature, signature_len); + if(ret) { + return -1; + } + + return 0; +#endif +} + +#endif /* LIBSSH2_RSA_SHA2 */ + + +/* * hostkey_method_ssh_rsa_dtor * * Shutdown the hostkey @@ -260,6 +419,35 @@ static const LIBSSH2_HOSTKEY_METHOD hostkey_method_ssh_rsa = { NULL, /* encrypt */ hostkey_method_ssh_rsa_dtor, }; + +#if LIBSSH2_RSA_SHA2 + +static const LIBSSH2_HOSTKEY_METHOD hostkey_method_ssh_rsa_sha2_256 = { + "rsa-sha2-256", + SHA256_DIGEST_LENGTH, + hostkey_method_ssh_rsa_init, + hostkey_method_ssh_rsa_initPEM, + hostkey_method_ssh_rsa_initPEMFromMemory, + hostkey_method_ssh_rsa_sha2_256_sig_verify, + hostkey_method_ssh_rsa_sha2_256_signv, + NULL, /* encrypt */ + hostkey_method_ssh_rsa_dtor, +}; + +static const LIBSSH2_HOSTKEY_METHOD hostkey_method_ssh_rsa_sha2_512 = { + "rsa-sha2-512", + SHA512_DIGEST_LENGTH, + hostkey_method_ssh_rsa_init, + hostkey_method_ssh_rsa_initPEM, + hostkey_method_ssh_rsa_initPEMFromMemory, + hostkey_method_ssh_rsa_sha2_512_sig_verify, + hostkey_method_ssh_rsa_sha2_512_signv, + NULL, /* encrypt */ + hostkey_method_ssh_rsa_dtor, +}; + +#endif /* LIBSSH2_RSA_SHA2 */ + #endif /* LIBSSH2_RSA */ #if LIBSSH2_DSA @@ -1041,6 +1229,10 @@ static const LIBSSH2_HOSTKEY_METHOD *hostkey_methods[] = { &hostkey_method_ssh_ed25519, #endif #if LIBSSH2_RSA +#if LIBSSH2_RSA_SHA2 + &hostkey_method_ssh_rsa_sha2_512, + &hostkey_method_ssh_rsa_sha2_256, +#endif /* LIBSSH2_RSA_SHA2 */ &hostkey_method_ssh_rsa, #endif /* LIBSSH2_RSA */ #if LIBSSH2_DSA diff --git a/src/kex.c b/src/kex.c index c300ecb..8f02808 100644 --- a/src/kex.c +++ b/src/kex.c @@ -3026,6 +3026,17 @@ kex_method_ssh_curve25519_sha256 = { }; #endif +/* this kex method signals that client can receive extensions + * as described in https://datatracker.ietf.org/doc/html/rfc8308 +*/ + +static const LIBSSH2_KEX_METHOD +kex_method_extension_negotiation = { + "ext-info-c", + NULL, + 0, +}; + static const LIBSSH2_KEX_METHOD *libssh2_kex_methods[] = { #if LIBSSH2_ED25519 &kex_method_ssh_curve25519_sha256, @@ -3043,6 +3054,7 @@ static const LIBSSH2_KEX_METHOD *libssh2_kex_methods[] = { &kex_method_diffie_helman_group14_sha1, &kex_method_diffie_helman_group1_sha1, &kex_method_diffie_helman_group_exchange_sha1, + &kex_method_extension_negotiation, NULL }; @@ -3978,6 +3990,11 @@ libssh2_session_method_pref(LIBSSH2_SESSION * session, int method_type, mlist = NULL; break; + case LIBSSH2_METHOD_SIGN_ALGO: + prefvar = &session->sign_algo_prefs; + mlist = NULL; + break; + default: return _libssh2_error(session, LIBSSH2_ERROR_INVAL, "Invalid parameter specified for method_type"); @@ -4073,6 +4090,11 @@ LIBSSH2_API int libssh2_session_supported_algs(LIBSSH2_SESSION* session, _libssh2_comp_methods(session); break; + case LIBSSH2_METHOD_SIGN_ALGO: + /* no built-in supported list due to backend support */ + mlist = NULL; + break; + default: return _libssh2_error(session, LIBSSH2_ERROR_METHOD_NOT_SUPPORTED, "Unknown method type"); diff --git a/src/libgcrypt.c b/src/libgcrypt.c index 0aff176..f6e9b64 100644 --- a/src/libgcrypt.c +++ b/src/libgcrypt.c @@ -664,4 +664,22 @@ _libssh2_dh_dtor(_libssh2_dh_ctx *dhctx) *dhctx = NULL; } +/* _libssh2_supported_key_sign_algorithms + * + * Return supported key hash algo upgrades, see crypto.h + * + */ + +const char * +_libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len) +{ + (void)session; + (void)key_method; + (void)key_method_len; + + return NULL; +} + #endif /* LIBSSH2_LIBGCRYPT */ diff --git a/src/libgcrypt.h b/src/libgcrypt.h index 298c65e..95876b9 100644 --- a/src/libgcrypt.h +++ b/src/libgcrypt.h @@ -55,6 +55,7 @@ #define LIBSSH2_3DES 1 #define LIBSSH2_RSA 1 +#define LIBSSH2_RSA_SHA2 0 #define LIBSSH2_DSA 1 #define LIBSSH2_ECDSA 0 #define LIBSSH2_ED25519 0 diff --git a/src/libssh2_priv.h b/src/libssh2_priv.h index da488b7..aff791e 100644 --- a/src/libssh2_priv.h +++ b/src/libssh2_priv.h @@ -640,6 +640,13 @@ struct _LIBSSH2_SESSION unsigned char server_hostkey_sha256[SHA256_DIGEST_LENGTH]; int server_hostkey_sha256_valid; + /* public key algorithms accepted as comma separated list */ + char *server_sign_algorithms; + size_t server_sign_algorithms_len; + + /* key signing algorithm preferences -- NULL yields server order */ + char *sign_algo_prefs; + /* (remote as source of data -- packet_read ) */ libssh2_endpoint_data remote; @@ -1006,6 +1013,7 @@ _libssh2_debug(LIBSSH2_SESSION * session, int context, const char *format, ...) #define SSH_MSG_DEBUG 4 #define SSH_MSG_SERVICE_REQUEST 5 #define SSH_MSG_SERVICE_ACCEPT 6 +#define SSH_MSG_EXT_INFO 7 #define SSH_MSG_KEXINIT 20 #define SSH_MSG_NEWKEYS 21 diff --git a/src/mbedtls.c b/src/mbedtls.c index 4629ce4..dc76ef5 100644 --- a/src/mbedtls.c +++ b/src/mbedtls.c @@ -1247,5 +1247,24 @@ _libssh2_mbedtls_ecdsa_free(libssh2_ecdsa_ctx *ctx) mbedtls_free(ctx); } + +/* _libssh2_supported_key_sign_algorithms + * + * Return supported key hash algo upgrades, see crypto.h + * + */ + +const char * +_libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len) +{ + (void)session; + (void)key_method; + (void)key_method_len; + + return NULL; +} + #endif /* LIBSSH2_ECDSA */ #endif /* LIBSSH2_MBEDTLS */ diff --git a/src/mbedtls.h b/src/mbedtls.h index 671932c..0450113 100644 --- a/src/mbedtls.h +++ b/src/mbedtls.h @@ -71,6 +71,7 @@ #define LIBSSH2_3DES 1 #define LIBSSH2_RSA 1 +#define LIBSSH2_RSA_SHA2 0 #define LIBSSH2_DSA 0 #ifdef MBEDTLS_ECDSA_C # define LIBSSH2_ECDSA 1 diff --git a/src/openssl.c b/src/openssl.c index 7a6810f..72a85b3 100644 --- a/src/openssl.c +++ b/src/openssl.c @@ -154,21 +154,57 @@ _libssh2_rsa_new(libssh2_rsa_ctx ** rsa, } int -_libssh2_rsa_sha1_verify(libssh2_rsa_ctx * rsactx, +_libssh2_rsa_sha2_verify(libssh2_rsa_ctx * rsactx, + size_t hash_len, const unsigned char *sig, unsigned long sig_len, const unsigned char *m, unsigned long m_len) { - unsigned char hash[SHA_DIGEST_LENGTH]; int ret; + int nid_type; + unsigned char *hash = malloc(hash_len); + if(hash == NULL) + return -1; + + if(hash_len == SHA_DIGEST_LENGTH) { + nid_type = NID_sha1; + ret = _libssh2_sha1(m, m_len, hash); + } + else if(hash_len == SHA256_DIGEST_LENGTH) { + nid_type = NID_sha256; + ret = _libssh2_sha256(m, m_len, hash); + + } + else if(hash_len == SHA512_DIGEST_LENGTH) { + nid_type = NID_sha512; + ret = _libssh2_sha512(m, m_len, hash); + } + else + ret = -1; /* unsupported digest */ - if(_libssh2_sha1(m, m_len, hash)) + if(ret != 0) { + free(hash); return -1; /* failure */ - ret = RSA_verify(NID_sha1, hash, SHA_DIGEST_LENGTH, + } + + ret = RSA_verify(nid_type, hash, hash_len, (unsigned char *) sig, sig_len, rsactx); + + free(hash); + return (ret == 1) ? 0 : -1; } +int +_libssh2_rsa_sha1_verify(libssh2_rsa_ctx * rsactx, + const unsigned char *sig, + unsigned long sig_len, + const unsigned char *m, unsigned long m_len) +{ + return _libssh2_rsa_sha2_verify(rsactx, SHA_DIGEST_LENGTH, sig, sig_len, m, + m_len); +} + #if LIBSSH2_DSA int _libssh2_dsa_new(libssh2_dsa_ctx ** dsactx, @@ -1876,7 +1912,7 @@ _libssh2_ed25519_new_public(libssh2_ed25519_ctx ** ed_ctx, int -_libssh2_rsa_sha1_sign(LIBSSH2_SESSION * session, +_libssh2_rsa_sha2_sign(LIBSSH2_SESSION * session, libssh2_rsa_ctx * rsactx, const unsigned char *hash, size_t hash_len, @@ -1893,7 +1929,17 @@ _libssh2_rsa_sha1_sign(LIBSSH2_SESSION * session, return -1; } - ret = RSA_sign(NID_sha1, hash, hash_len, sig, &sig_len, rsactx); + if(hash_len == SHA_DIGEST_LENGTH) + ret = RSA_sign(NID_sha1, hash, hash_len, sig, &sig_len, rsactx); + else if(hash_len == SHA256_DIGEST_LENGTH) + ret = RSA_sign(NID_sha256, hash, hash_len, sig, &sig_len, rsactx); + else if(hash_len == SHA512_DIGEST_LENGTH) + ret = RSA_sign(NID_sha512, hash, hash_len, sig, &sig_len, rsactx); + else { + _libssh2_error(session, LIBSSH2_ERROR_PROTO, + "Unsupported hash digest length"); + ret = -1; + } if(!ret) { LIBSSH2_FREE(session, sig); @@ -1906,6 +1952,19 @@ _libssh2_rsa_sha1_sign(LIBSSH2_SESSION * session, return 0; } + +int +_libssh2_rsa_sha1_sign(LIBSSH2_SESSION * session, + libssh2_rsa_ctx * rsactx, + const unsigned char *hash, + size_t hash_len, + unsigned char **signature, size_t *signature_len) +{ + return _libssh2_rsa_sha2_sign(session, rsactx, hash, hash_len, + signature, signature_len); +} + + #if LIBSSH2_DSA int _libssh2_dsa_sha1_sign(libssh2_dsa_ctx * dsactx, @@ -3283,4 +3342,27 @@ _libssh2_dh_dtor(_libssh2_dh_ctx *dhctx) *dhctx = NULL; } +/* _libssh2_supported_key_sign_algorithms + * + * Return supported key hash algo upgrades, see crypto.h + * + */ + +const char * +_libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len) +{ + (void)session; + +#if LIBSSH2_RSA_SHA2 + if(key_method_len == 7 && + memcmp(key_method, "ssh-rsa", key_method_len) == 0) { + return "rsa-sha2-512,rsa-sha2-256,ssh-rsa"; + } +#endif + + return NULL; +} + #endif /* LIBSSH2_OPENSSL */ diff --git a/src/openssl.h b/src/openssl.h index 658b040..2a002b4 100644 --- a/src/openssl.h +++ b/src/openssl.h @@ -64,8 +64,10 @@ #ifdef OPENSSL_NO_RSA # define LIBSSH2_RSA 0 +# define LIBSSH2_RSA_SHA2 0 #else # define LIBSSH2_RSA 1 +# define LIBSSH2_RSA_SHA2 1 #endif #ifdef OPENSSL_NO_DSA diff --git a/src/packet.c b/src/packet.c index 04937d6..686be5c 100644 --- a/src/packet.c +++ b/src/packet.c @@ -616,6 +616,75 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data, return 0; /* + byte SSH_MSG_EXT_INFO + uint32 nr-extensions + [repeat "nr-extensions" times] + string extension-name [RFC8308] + string extension-value (binary) + */ + + case SSH_MSG_EXT_INFO: + if(datalen >= 5) { + uint32_t nr_extensions = 0; + struct string_buf buf; + buf.data = (unsigned char *)data; + buf.dataptr = buf.data; + buf.len = datalen; + buf.dataptr += 1; /* advance past type */ + + if(_libssh2_get_u32(&buf, &nr_extensions) != 0) { + rc = _libssh2_error(session, LIBSSH2_ERROR_PROTO, + "Invalid extension info received"); + } + + while(rc == 0 && nr_extensions > 0) { + + size_t name_len = 0; + size_t value_len = 0; + unsigned char *name = NULL; + unsigned char *value = NULL; + + nr_extensions -= 1; + + _libssh2_get_string(&buf, &name, &name_len); + _libssh2_get_string(&buf, &value, &value_len); + + if(name != NULL && value != NULL) { + _libssh2_debug(session, + LIBSSH2_TRACE_KEX, + "Server to Client extension %.*s: %.*s", + name_len, name, value_len, value); + } + + if(name_len == 15 && + memcmp(name, "server-sig-algs", 15) == 0) { + if(session->server_sign_algorithms) { + LIBSSH2_FREE(session, + session->server_sign_algorithms); + } + + session->server_sign_algorithms = + LIBSSH2_ALLOC(session, + value_len); + + if(session->server_sign_algorithms) { + session->server_sign_algorithms_len = value_len; + memcpy(session->server_sign_algorithms, + value, value_len); + } + else { + rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC, + "memory for server sign algo"); + } + } + } + } + + LIBSSH2_FREE(session, data); + session->packAdd_state = libssh2_NB_state_idle; + return rc; + + /* byte SSH_MSG_GLOBAL_REQUEST string request name in US-ASCII only boolean want reply diff --git a/src/userauth.c b/src/userauth.c index 4442eee..988dc17 100644 --- a/src/userauth.c +++ b/src/userauth.c @@ -1086,6 +1086,148 @@ static int plain_method_len(const char *method, size_t method_len) return method_len; } +/** + * @function _libssh2_key_sign_algorithm + * @abstract Upgrades the algorithm used for public key signing RFC 8332 + * @discussion Based on the incoming key_method value, this function + * will upgrade the key method input based on user preferences, + * server support algos and crypto backend support + * @related _libssh2_supported_key_sign_algorithms() + * @param key_method current key method, usually the default key sig method + * @param key_method_len length of the key method buffer + * @result error code or zero on success + */ + +static int +_libssh2_key_sign_algorithm(LIBSSH2_SESSION *session, + unsigned char **key_method, + size_t *key_method_len) +{ + const char *s = NULL; + const char *a = NULL; + const char *match = NULL; + const char *p = NULL; + const char *f = NULL; + char *i = NULL; + int p_len = 0; + int f_len = 0; + int rc = 0; + int match_len = 0; + char *filtered_algs = NULL; + + const char *supported_algs = + _libssh2_supported_key_sign_algorithms(session, + *key_method, + *key_method_len); + + if(supported_algs == NULL || session->server_sign_algorithms == NULL) { + /* no upgrading key algorithm supported, do nothing */ + return LIBSSH2_ERROR_NONE; + } + + filtered_algs = LIBSSH2_ALLOC(session, strlen(supported_algs) + 1); + if(!filtered_algs) { + rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC, + "Unable to allocate filtered algs"); + return rc; + } + + s = session->server_sign_algorithms; + i = filtered_algs; + + /* this walks the server algo list and the supported algo list and creates + a filtered list that includes matches */ + + while(s && *s) { + p = strchr(s, ','); + p_len = p ? (p - s) : (int) strlen(s); + a = supported_algs; + + while(a && *a) { + f = strchr(a, ','); + f_len = f ? (f - a) : (int) strlen(a); + + if(f_len == p_len && memcmp(a, s, p_len)) { + + if(i != filtered_algs) { + memcpy(i, ",", 1); + i += 1; + } + + memcpy(i, s, p_len); + i += p_len; + } + + a = f ? (f + 1) : NULL; + } + + s = p ? (p + 1) : NULL; + } + + filtered_algs[i - filtered_algs] = '\0'; + + if(session->sign_algo_prefs) { + s = session->sign_algo_prefs; + } + else { + s = supported_algs; + } + + /* now that we have the possible supported algos, match based on the prefs + or what is supported by the crypto backend, look for a match */ + + while(s && *s && !match) { + p = strchr(s, ','); + p_len = p ? (p - s) : (int) strlen(s); + a = filtered_algs; + + while(a && *a && !match) { + f = strchr(a, ','); + f_len = f ? (f - a) : (int) strlen(a); + + if(f_len == p_len && memcmp(a, s, p_len)) { + /* found a match, upgrade key method */ + match = s; + match_len = p_len; + } + else { + a = f ? (f + 1) : NULL; + } + } + + s = p ? (p + 1) : NULL; + } + + if(match != NULL) { + if(*key_method) + LIBSSH2_FREE(session, *key_method); + + *key_method = LIBSSH2_ALLOC(session, match_len); + if(key_method) { + memcpy(*key_method, match, match_len); + *key_method_len = match_len; + + _libssh2_debug(session, LIBSSH2_TRACE_KEX, + "Signing using %.*s", match_len, match); + } + else { + *key_method_len = 0; + rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC, + "Unable to allocate key method upgrade"); + } + } + else { + /* no match was found */ + rc = _libssh2_error(session, LIBSSH2_ERROR_METHOD_NONE, + "No signing signature matched"); + } + + if(filtered_algs) + LIBSSH2_FREE(session, filtered_algs); + + return rc; +} + int _libssh2_userauth_publickey(LIBSSH2_SESSION *session, const char *username, @@ -1144,15 +1286,14 @@ _libssh2_userauth_publickey(LIBSSH2_SESSION *session, memcpy(session->userauth_pblc_method, pubkeydata + 4, session->userauth_pblc_method_len); } - /* - * The length of the method name read from plaintext prefix in the - * file must match length embedded in the key. - * TODO: The data should match too but we don't check that. Should we? - */ - else if(session->userauth_pblc_method_len != - _libssh2_ntohu32(pubkeydata)) - return _libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_UNVERIFIED, - "Invalid public key"); + + /* upgrade key key signing algo needed */ + rc = _libssh2_key_sign_algorithm(session, + &session->userauth_pblc_method, + &session->userauth_pblc_method_len); + + if(rc) + return rc; /* * 45 = packet_type(1) + username_len(4) + servicename_len(4) + diff --git a/src/wincng.c b/src/wincng.c index 9ae8dde..58e2251 100644 --- a/src/wincng.c +++ b/src/wincng.c @@ -2591,4 +2591,22 @@ fb: return _libssh2_wincng_bignum_mod_exp(secret, f, dhctx->bn, p); } +/* _libssh2_supported_key_sign_algorithms + * + * Return supported key hash algo upgrades, see crypto.h + * + */ + +const char * +_libssh2_supported_key_sign_algorithms(LIBSSH2_SESSION *session, + unsigned char *key_method, + size_t key_method_len) +{ + (void)session; + (void)key_method; + (void)key_method_len; + + return NULL; +} + #endif /* LIBSSH2_WINCNG */ diff --git a/src/wincng.h b/src/wincng.h index eaf6f90..538cc43 100644 --- a/src/wincng.h +++ b/src/wincng.h @@ -63,6 +63,7 @@ #define LIBSSH2_3DES 1 #define LIBSSH2_RSA 1 +#define LIBSSH2_RSA_SHA2 0 #define LIBSSH2_DSA 1 #define LIBSSH2_ECDSA 0 #define LIBSSH2_ED25519 0 -- 1.8.3.1
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