Mercurial > dropbear
view libtomcrypt/testprof/test.key @ 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 | 1b9e69c058d2 |
children |
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-----BEGIN RSA PRIVATE KEY----- MIICXgIBAAKBgQDPmt5kitrIMyCp14MxGVSymoWnobd1M7aprIQks97bfYUtlmXl P3KVJJ8oaMpP20QcPmASit0mpev/C17UiDhJKm5bvxI3R70Fa7zb8+7kEY5BaHxh E9dCyIC+No/cCItPrKTidgzJY2xJWJPtzKrcJTsKYD+LVDrDTTHnlKRE/QIDAQAB AoGBAMhiuereRFMdVpfZl54azzAeCohFhikwo02fYWVz4NaHj7bzBqOC3Hys/pso mq79+/4vDtiXBOO7H9HsDbqjSX9HrIpEBH6GtzlCP60etw6lUfRAYx79veqfQZ+o kB1vClqVExENgK9fZJiKLHhoZbAri6JTh8rxZASr8nvbg8iBAkEA975eI8MyP7+L jjru/PzL5ffxC7xCgq7Vej7K99VpP2Qloh+3dXUFkkLruPHzCgXjlNFVeDWgNqCb fJKEbN3cTQJBANaGDoVCCwQIhCFg8A4NiP0eNhBlTx5TtAhygFw/WWYX5pjy6Wx6 Bkysdj3tjKHOrRu9tH0ovOMOOI2Z2AW1o3ECQG3rwy0u8F6kiDEFKQCK0ZUpm4PP ddsx43on3jp0MAx2TNRQKkAtOdmZY6ldgK5TypQ/BSMe+AUE4bg18hezoIkCQQCr kIj6YAgpUJpDi6BQzNha/pdkY3F0IqMgAlrP68YWlVTRy6uNGsYA+giSnHHVUlI1 lnFLi5IM0Om/rWMLpemxAkEA3MwnyOTcYkjVm6/1q2D2If1T4rddCckaoQSp/GEs XQRYOlo58UohVmf9zCCjj3gYWnk9Lo5+hgrmqDPBBBdKnw== -----END RSA PRIVATE KEY-----