Mercurial > dropbear
view signkey.h @ 1788:1fc0012b9c38
Fix handling of replies to global requests (#112)
The current code assumes that all global requests want / need a reply.
This isn't always true and the request itself indicates if it wants a
reply or not.
It causes a specific problem with [email protected] messages.
These are sent by OpenSSH after authentication to inform the client of
potential other host keys for the host. This can be used to add a new
type of host key or to rotate host keys.
The initial information message from the server is sent as a global
request, but with want_reply set to false. This means that the server
doesn't expect an answer to this message. Instead the client needs to
send a prove request as a reply if it wants to receive proof of
ownership for the host keys.
The bug doesn't cause any current problems with due to how OpenSSH
treats receiving the failure message. It instead treats it as a
keepalive message and further ignores it.
Arguably this is a protocol violation though of Dropbear and it is only
accidental that it doesn't cause a problem with OpenSSH.
The bug was found when adding host keys support to libssh, which is more
strict protocol wise and treats the unexpected failure message an error,
also see https://gitlab.com/libssh/libssh-mirror/-/merge_requests/145
for more information.
The fix here is to honor the want_reply flag in the global request and
to only send a reply if the other side expects a reply.
author | Dirkjan Bussink <d.bussink@gmail.com> |
---|---|
date | Thu, 10 Dec 2020 16:13:13 +0100 |
parents | d5cdc60db08e |
children | 35d504d59c05 |
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/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #ifndef DROPBEAR_SIGNKEY_H_ #define DROPBEAR_SIGNKEY_H_ #include "buffer.h" /* Forward declarations */ struct dropbear_DSS_Key; struct dropbear_RSA_Key; struct dropbear_ED25519_Key; /* Must match with signature_type below */ enum signkey_type { #if DROPBEAR_RSA DROPBEAR_SIGNKEY_RSA, #endif #if DROPBEAR_DSS DROPBEAR_SIGNKEY_DSS, #endif #if DROPBEAR_ECDSA DROPBEAR_SIGNKEY_ECDSA_NISTP256, DROPBEAR_SIGNKEY_ECDSA_NISTP384, DROPBEAR_SIGNKEY_ECDSA_NISTP521, #endif /* DROPBEAR_ECDSA */ #if DROPBEAR_ED25519 DROPBEAR_SIGNKEY_ED25519, #endif DROPBEAR_SIGNKEY_NUM_NAMED, DROPBEAR_SIGNKEY_ECDSA_KEYGEN = 70, /* just "ecdsa" for keygen */ DROPBEAR_SIGNKEY_ANY = 80, DROPBEAR_SIGNKEY_NONE = 90, }; /* Must match with signkey_type above, apart from rsa */ enum signature_type { #if DROPBEAR_DSS DROPBEAR_SIGNATURE_DSS = DROPBEAR_SIGNKEY_DSS, #endif #if DROPBEAR_ECDSA DROPBEAR_SIGNATURE_ECDSA_NISTP256 = DROPBEAR_SIGNKEY_ECDSA_NISTP256, DROPBEAR_SIGNATURE_ECDSA_NISTP384 = DROPBEAR_SIGNKEY_ECDSA_NISTP384, DROPBEAR_SIGNATURE_ECDSA_NISTP521 = DROPBEAR_SIGNKEY_ECDSA_NISTP521, #endif /* DROPBEAR_ECDSA */ #if DROPBEAR_ED25519 DROPBEAR_SIGNATURE_ED25519 = DROPBEAR_SIGNKEY_ED25519, #endif #if DROPBEAR_RSA_SHA1 DROPBEAR_SIGNATURE_RSA_SHA1 = 100, /* ssh-rsa signature (sha1) */ #endif #if DROPBEAR_RSA_SHA256 DROPBEAR_SIGNATURE_RSA_SHA256 = 101, /* rsa-sha2-256 signature. has a ssh-rsa key */ #endif DROPBEAR_SIGNATURE_NONE = DROPBEAR_SIGNKEY_NONE, }; /* Sources for signing keys */ typedef enum { SIGNKEY_SOURCE_RAW_FILE, SIGNKEY_SOURCE_AGENT, SIGNKEY_SOURCE_INVALID, } signkey_source; struct SIGN_key { enum signkey_type type; signkey_source source; char *filename; #if DROPBEAR_DSS struct dropbear_DSS_Key * dsskey; #endif #if DROPBEAR_RSA struct dropbear_RSA_Key * rsakey; #endif #if DROPBEAR_ECDSA #if DROPBEAR_ECC_256 ecc_key * ecckey256; #endif #if DROPBEAR_ECC_384 ecc_key * ecckey384; #endif #if DROPBEAR_ECC_521 ecc_key * ecckey521; #endif #endif #if DROPBEAR_ED25519 struct dropbear_ED25519_Key * ed25519key; #endif }; typedef struct SIGN_key sign_key; sign_key * new_sign_key(void); const char* signkey_name_from_type(enum signkey_type type, unsigned int *namelen); enum signkey_type signkey_type_from_name(const char* name, unsigned int namelen); const char* signature_name_from_type(enum signature_type type, unsigned int *namelen); enum signature_type signature_type_from_name(const char* name, unsigned int namelen); enum signkey_type signkey_type_from_signature(enum signature_type sigtype); enum signature_type signature_type_from_signkey(enum signkey_type keytype); int buf_get_pub_key(buffer *buf, sign_key *key, enum signkey_type *type); int buf_get_priv_key(buffer* buf, sign_key *key, enum signkey_type *type); void buf_put_pub_key(buffer* buf, sign_key *key, enum signkey_type type); void buf_put_priv_key(buffer* buf, sign_key *key, enum signkey_type type); void sign_key_free(sign_key *key); void buf_put_sign(buffer* buf, sign_key *key, enum signature_type sigtype, const buffer *data_buf); #if DROPBEAR_SIGNKEY_VERIFY int buf_verify(buffer * buf, sign_key *key, enum signature_type expect_sigtype, const buffer *data_buf); char * sign_key_fingerprint(const unsigned char* keyblob, unsigned int keybloblen); #endif int cmp_base64_key(const unsigned char* keyblob, unsigned int keybloblen, const unsigned char* algoname, unsigned int algolen, const buffer * line, char ** fingerprint); void** signkey_key_ptr(sign_key *key, enum signkey_type type); #endif /* DROPBEAR_SIGNKEY_H_ */