Mercurial > dropbear
annotate ecc.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 | d68d61e7056a |
children |
rev | line source |
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1036
deed0571cacc
DROPBEAR_ prefix for include guards to avoid collisions
Thorsten Horstmann <thorsten.horstmann@web.de>
parents:
857
diff
changeset
|
1 #ifndef DROPBEAR_DROPBEAR_ECC_H |
deed0571cacc
DROPBEAR_ prefix for include guards to avoid collisions
Thorsten Horstmann <thorsten.horstmann@web.de>
parents:
857
diff
changeset
|
2 #define DROPBEAR_DROPBEAR_ECC_H |
756 | 3 |
4 #include "includes.h" | |
5 | |
6 #include "buffer.h" | |
7 | |
1295
750ec4ec4cbe
Convert #ifdef to #if, other build changes
Matt Johnston <matt@ucc.asn.au>
parents:
1276
diff
changeset
|
8 #if DROPBEAR_ECC |
756 | 9 |
10 struct dropbear_ecc_curve { | |
857 | 11 int ltc_size; /* to match the byte sizes in ltc_ecc_sets[] */ |
12 const ltc_ecc_set_type *dp; /* curve domain parameters */ | |
793
70625eed40c9
A bit of work on ecdsa for host/auth keys
Matt Johnston <matt@ucc.asn.au>
parents:
767
diff
changeset
|
13 const struct ltc_hash_descriptor *hash_desc; |
1107
4f3335bba3d9
Turn dropbear_ecc_curve's name into const char *
Gaël PORTAY <gael.portay@gmail.com>
parents:
1036
diff
changeset
|
14 const char *name; |
756 | 15 }; |
16 | |
767
e465ed10c51d
Be safer with how we handle ltc_ecc_sets[] (particularly with
Matt Johnston <matt@ucc.asn.au>
parents:
766
diff
changeset
|
17 extern struct dropbear_ecc_curve ecc_curve_nistp256; |
e465ed10c51d
Be safer with how we handle ltc_ecc_sets[] (particularly with
Matt Johnston <matt@ucc.asn.au>
parents:
766
diff
changeset
|
18 extern struct dropbear_ecc_curve ecc_curve_nistp384; |
e465ed10c51d
Be safer with how we handle ltc_ecc_sets[] (particularly with
Matt Johnston <matt@ucc.asn.au>
parents:
766
diff
changeset
|
19 extern struct dropbear_ecc_curve ecc_curve_nistp521; |
e465ed10c51d
Be safer with how we handle ltc_ecc_sets[] (particularly with
Matt Johnston <matt@ucc.asn.au>
parents:
766
diff
changeset
|
20 extern struct dropbear_ecc_curve *dropbear_ecc_curves[]; |
e465ed10c51d
Be safer with how we handle ltc_ecc_sets[] (particularly with
Matt Johnston <matt@ucc.asn.au>
parents:
766
diff
changeset
|
21 |
1276
9169e4e7cbee
fix empty C prototypes
Francois Perrad <francois.perrad@gadz.org>
parents:
1107
diff
changeset
|
22 void dropbear_ecc_fill_dp(void); |
793
70625eed40c9
A bit of work on ecdsa for host/auth keys
Matt Johnston <matt@ucc.asn.au>
parents:
767
diff
changeset
|
23 struct dropbear_ecc_curve* curve_for_dp(const ltc_ecc_set_type *dp); |
756 | 24 |
857 | 25 /* "pubkey" refers to a point, but LTC uses ecc_key structure for both public |
26 and private keys */ | |
765
5503e05ab3a4
- Rename buf_put_ecc_pubkey_string() to buf_put_ecc_raw_pubkey_string()
Matt Johnston <matt@ucc.asn.au>
parents:
762
diff
changeset
|
27 void buf_put_ecc_raw_pubkey_string(buffer *buf, ecc_key *key); |
5503e05ab3a4
- Rename buf_put_ecc_pubkey_string() to buf_put_ecc_raw_pubkey_string()
Matt Johnston <matt@ucc.asn.au>
parents:
762
diff
changeset
|
28 ecc_key * buf_get_ecc_raw_pubkey(buffer *buf, const struct dropbear_ecc_curve *curve); |
756 | 29 int buf_get_ecc_privkey_string(buffer *buf, ecc_key *key); |
30 | |
1459
06d52bcb8094
Pointer parameter could be declared as pointing to const
Francois Perrad <francois.perrad@gadz.org>
parents:
1295
diff
changeset
|
31 mp_int * dropbear_ecc_shared_secret(ecc_key *pub_key, const ecc_key *priv_key); |
756 | 32 |
33 #endif | |
34 | |
1036
deed0571cacc
DROPBEAR_ prefix for include guards to avoid collisions
Thorsten Horstmann <thorsten.horstmann@web.de>
parents:
857
diff
changeset
|
35 #endif /* DROPBEAR_DROPBEAR_ECC_H */ |