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SUSE:SLE-15-SP4:Update
libgit2.28263
0001-ssh-verify-the-remote-s-host-key-against-k...
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File 0001-ssh-verify-the-remote-s-host-key-against-known_hosts.patch of Package libgit2.28263
From 67126da8f5c113b86e12d6d88e284a66fc7f346f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Carlos=20Mart=C3=ADn=20Nieto?= <carlosmn@github.com> Date: Tue, 1 Nov 2022 12:54:29 +0100 Subject: [PATCH 1/6] ssh: verify the remote's host key against known_hosts if it exists It turns out this has been available in libssh2 for a long time and we should have been verifying this the whole time. --- src/transports/ssh.c | 309 +++++++++++++++++++++++++++++++------------ 1 file changed, 222 insertions(+), 87 deletions(-) diff -urp libgit2-1.3.0.orig/src/transports/ssh.c libgit2-1.3.0/src/transports/ssh.c --- libgit2-1.3.0.orig/src/transports/ssh.c 2023-03-15 14:28:08.786626336 -0500 +++ libgit2-1.3.0/src/transports/ssh.c 2023-03-15 14:44:27.623793631 -0500 @@ -508,6 +508,224 @@ static int _git_ssh_session_create( return 0; } +/* + * Returns the typemask argument to pass to libssh2_knownhost_check{,p} based on + * the type of key that libssh2_session_hostkey returns. + */ +static int fingerprint_type_mask(int keytype) +{ + int mask = LIBSSH2_KNOWNHOST_TYPE_PLAIN | LIBSSH2_KNOWNHOST_KEYENC_RAW; + return mask; + + switch (keytype) { + case LIBSSH2_HOSTKEY_TYPE_RSA: + mask |= LIBSSH2_KNOWNHOST_KEY_SSHRSA; + break; + case LIBSSH2_HOSTKEY_TYPE_DSS: + mask |= LIBSSH2_KNOWNHOST_KEY_SSHDSS; + break; +#ifdef LIBSSH2_HOSTKEY_TYPE_ECDSA_256 + case LIBSSH2_HOSTKEY_TYPE_ECDSA_256: + mask |= LIBSSH2_KNOWNHOST_KEY_ECDSA_256; + break; + case LIBSSH2_HOSTKEY_TYPE_ECDSA_384: + mask |= LIBSSH2_KNOWNHOST_KEY_ECDSA_384; + break; + case LIBSSH2_HOSTKEY_TYPE_ECDSA_521: + mask |= LIBSSH2_KNOWNHOST_KEY_ECDSA_521; + break; +#endif +#ifdef LIBSSH2_HOSTKEY_TYPE_ED25519 + case LIBSSH2_HOSTKEY_TYPE_ED25519: + mask |= LIBSSH2_KNOWNHOST_KEY_ED25519; + break; +#endif + } + + return mask; +} + +#define KNOWN_HOSTS_FILE ".ssh/known_hosts" + +/* + * Check the host against the user's known_hosts file. + * + * Returns 1/0 for valid/''not-valid or <0 for an error + */ +static int check_against_known_hosts( + LIBSSH2_SESSION *session, + const char *hostname, + int port, + const char *key, + size_t key_len, + int key_type) +{ + int error, check, typemask, ret = 0; + char *path = NULL; + const char *home; + LIBSSH2_KNOWNHOSTS *known_hosts = NULL; + struct libssh2_knownhost *host = NULL; + + home = getenv ("HOME"); + if (!home) + return -1; + + path = (char *) malloc (strlen (home) + strlen (KNOWN_HOSTS_FILE) + 2); + sprintf (path, "%s/%s", home, KNOWN_HOSTS_FILE); + + if ((known_hosts = libssh2_knownhost_init(session)) == NULL) { + ssh_error(session, "error initializing known hosts"); + ret = -1; + goto out; + } + + /* + * Try to read the file and consider not finding it as not trusting the + * host rather than an error. + */ + error = libssh2_knownhost_readfile(known_hosts, path, LIBSSH2_KNOWNHOST_FILE_OPENSSH); + if (error == LIBSSH2_ERROR_FILE) { + ret = 0; + goto out; + } + if (error < 0) { + ssh_error(session, "error reading known_hosts"); + ret = -1; + goto out; + } + + typemask = fingerprint_type_mask(key_type); + check = libssh2_knownhost_checkp(known_hosts, hostname, port, key, key_len, typemask, &host); + if (check == LIBSSH2_KNOWNHOST_CHECK_FAILURE) { + ssh_error(session, "error checking for known host"); + ret = -1; + goto out; + } + + ret = check == LIBSSH2_KNOWNHOST_CHECK_MATCH ? 1 : 0; + +out: + libssh2_knownhost_free(known_hosts); + free (path); + + return ret; +} + +/* + * Perform the check for the session's certificate against known hosts if + * possible and then ask the user if they have a callback. + * + * Returns 1/0 for valid/not-valid or <0 for an error + */ +static int check_certificate( + LIBSSH2_SESSION *session, + git_transport_certificate_check_cb check_cb, + void *check_cb_payload, + const char *host, + const char *portstr) +{ + git_cert_hostkey cert = {{ 0 }}; + const char *key; + size_t cert_len; + int cert_type, port, cert_valid = 0, error = 0; + + if ((key = libssh2_session_hostkey(session, &cert_len, &cert_type)) == NULL) { + ssh_error(session, "failed to retrieve hostkey"); + return -1; + } + + /* Try to parse the port as a number, if we can't then fall back to default */ + if (git__strntol32(&port, portstr, strlen(portstr), NULL, 10) < 0) + port = -1; + + if ((cert_valid = check_against_known_hosts(session, host, port, key, cert_len, cert_type)) < 0) + return -1; + + cert.parent.cert_type = GIT_CERT_HOSTKEY_LIBSSH2; + if (key != NULL) { + cert.type |= GIT_CERT_SSH_RAW; + cert.hostkey = key; + cert.hostkey_len = cert_len; + switch (cert_type) { + case LIBSSH2_HOSTKEY_TYPE_RSA: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_RSA; + break; + case LIBSSH2_HOSTKEY_TYPE_DSS: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_DSS; + break; + +#ifdef LIBSSH2_HOSTKEY_TYPE_ECDSA_256 + case LIBSSH2_HOSTKEY_TYPE_ECDSA_256: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_256; + break; + case LIBSSH2_HOSTKEY_TYPE_ECDSA_384: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_384; + break; + case LIBSSH2_KNOWNHOST_KEY_ECDSA_521: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_521; + break; +#endif + +#ifdef LIBSSH2_HOSTKEY_TYPE_ED25519 + case LIBSSH2_HOSTKEY_TYPE_ED25519: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ED25519; + break; +#endif + default: + cert.raw_type = GIT_CERT_SSH_RAW_TYPE_UNKNOWN; + } + } + +#ifdef LIBSSH2_HOSTKEY_HASH_SHA256 + key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA256); + if (key != NULL) { + cert.type |= GIT_CERT_SSH_SHA256; + memcpy(&cert.hash_sha256, key, 32); + } +#endif + + key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1); + if (key != NULL) { + cert.type |= GIT_CERT_SSH_SHA1; + memcpy(&cert.hash_sha1, key, 20); + } + + key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_MD5); + if (key != NULL) { + cert.type |= GIT_CERT_SSH_MD5; + memcpy(&cert.hash_md5, key, 16); + } + + if (cert.type == 0) { + git_error_set(GIT_ERROR_SSH, "unable to get the host key"); + return -1; + } + + git_error_clear(); + error = 0; + if (!cert_valid) { + git_error_set(GIT_ERROR_SSH, "invalid or unknown remote ssh hostkey"); + error = GIT_ECERTIFICATE; + } + + if (check_cb != NULL) { + git_cert_hostkey *cert_ptr = &cert; + git_error_state previous_error = {0}; + + git_error_state_capture(&previous_error, error); + error = check_cb((git_cert *) cert_ptr, cert_valid, host, check_cb_payload); + if (error == GIT_PASSTHROUGH) { + error = git_error_state_restore(&previous_error); + } else if (error < 0 && !git_error_last()) { + git_error_set(GIT_ERROR_NET, "user canceled hostkey check"); + } + + git_error_state_free(&previous_error); + } + + return error; +} + #define SSH_DEFAULT_PORT "22" static int _git_ssh_setup_conn( @@ -560,90 +778,9 @@ post_extract: if ((error = _git_ssh_session_create(&session, s->io)) < 0) goto done; - if (t->owner->certificate_check_cb != NULL) { - git_cert_hostkey cert = {{ 0 }}, *cert_ptr; - const char *key; - size_t cert_len; - int cert_type; - - cert.parent.cert_type = GIT_CERT_HOSTKEY_LIBSSH2; - - key = libssh2_session_hostkey(session, &cert_len, &cert_type); - if (key != NULL) { - cert.type |= GIT_CERT_SSH_RAW; - cert.hostkey = key; - cert.hostkey_len = cert_len; - switch (cert_type) { - case LIBSSH2_HOSTKEY_TYPE_RSA: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_RSA; - break; - case LIBSSH2_HOSTKEY_TYPE_DSS: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_DSS; - break; - -#ifdef LIBSSH2_HOSTKEY_TYPE_ECDSA_256 - case LIBSSH2_HOSTKEY_TYPE_ECDSA_256: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_256; - break; - case LIBSSH2_HOSTKEY_TYPE_ECDSA_384: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_384; - break; - case LIBSSH2_KNOWNHOST_KEY_ECDSA_521: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ECDSA_521; - break; -#endif - -#ifdef LIBSSH2_HOSTKEY_TYPE_ED25519 - case LIBSSH2_HOSTKEY_TYPE_ED25519: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_KEY_ED25519; - break; -#endif - default: - cert.raw_type = GIT_CERT_SSH_RAW_TYPE_UNKNOWN; - } - } - -#ifdef LIBSSH2_HOSTKEY_HASH_SHA256 - key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA256); - if (key != NULL) { - cert.type |= GIT_CERT_SSH_SHA256; - memcpy(&cert.hash_sha256, key, 32); - } -#endif - - key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1); - if (key != NULL) { - cert.type |= GIT_CERT_SSH_SHA1; - memcpy(&cert.hash_sha1, key, 20); - } - - key = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_MD5); - if (key != NULL) { - cert.type |= GIT_CERT_SSH_MD5; - memcpy(&cert.hash_md5, key, 16); - } - - if (cert.type == 0) { - git_error_set(GIT_ERROR_SSH, "unable to get the host key"); - error = -1; - goto done; - } - - /* We don't currently trust any hostkeys */ - git_error_clear(); - - cert_ptr = &cert; - - error = t->owner->certificate_check_cb((git_cert *) cert_ptr, 0, urldata.host, t->owner->message_cb_payload); - - if (error < 0 && error != GIT_PASSTHROUGH) { - if (!git_error_last()) - git_error_set(GIT_ERROR_NET, "user cancelled hostkey check"); - - goto done; - } - } - + if ((error = check_certificate(session, t->owner->certificate_check_cb, t->owner->message_cb_payload, urldata.host, urldata.port)) < 0) + goto done; + /* we need the username to ask for auth methods */ if (!urldata.username) { if ((error = request_creds(&cred, t, NULL, GIT_CREDENTIAL_USERNAME)) < 0)
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