openssh/authfd.h
djm@openbsd.org 4f7a56d5e0 upstream: Add protection for private keys at rest in RAM against
speculation and memory sidechannel attacks like Spectre, Meltdown, Rowhammer
and Rambleed. This change encrypts private keys when they are not in use with
a symmetic key that is derived from a relatively large "prekey" consisting of
random data (currently 16KB).

Attackers must recover the entire prekey with high accuracy before
they can attempt to decrypt the shielded private key, but the current
generation of attacks have bit error rates that, when applied
cumulatively to the entire prekey, make this unlikely.

Implementation-wise, keys are encrypted "shielded" when loaded and then
automatically and transparently unshielded when used for signatures or
when being saved/serialised.

Hopefully we can remove this in a few years time when computer
architecture has become less unsafe.

been in snaps for a bit already; thanks deraadt@

ok dtucker@ deraadt@

OpenBSD-Commit-ID: 19767213c312e46f94b303a512ef8e9218a39bd4
2019-06-21 14:24:35 +10:00

91 lines
3.0 KiB
C

/* $OpenBSD: authfd.h,v 1.45 2019/06/21 04:21:04 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Functions to interface with the SSH_AUTHENTICATION_FD socket.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
#ifndef AUTHFD_H
#define AUTHFD_H
/* List of identities returned by ssh_fetch_identitylist() */
struct ssh_identitylist {
size_t nkeys;
struct sshkey **keys;
char **comments;
};
int ssh_get_authentication_socket(int *fdp);
void ssh_close_authentication_socket(int sock);
int ssh_lock_agent(int sock, int lock, const char *password);
int ssh_fetch_identitylist(int sock, struct ssh_identitylist **idlp);
void ssh_free_identitylist(struct ssh_identitylist *idl);
int ssh_add_identity_constrained(int sock, struct sshkey *key,
const char *comment, u_int life, u_int confirm, u_int maxsign);
int ssh_remove_identity(int sock, struct sshkey *key);
int ssh_update_card(int sock, int add, const char *reader_id,
const char *pin, u_int life, u_int confirm);
int ssh_remove_all_identities(int sock, int version);
int ssh_agent_sign(int sock, const struct sshkey *key,
u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, const char *alg, u_int compat);
/* Messages for the authentication agent connection. */
#define SSH_AGENTC_REQUEST_RSA_IDENTITIES 1
#define SSH_AGENT_RSA_IDENTITIES_ANSWER 2
#define SSH_AGENTC_RSA_CHALLENGE 3
#define SSH_AGENT_RSA_RESPONSE 4
#define SSH_AGENT_FAILURE 5
#define SSH_AGENT_SUCCESS 6
#define SSH_AGENTC_ADD_RSA_IDENTITY 7
#define SSH_AGENTC_REMOVE_RSA_IDENTITY 8
#define SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES 9
/* private OpenSSH extensions for SSH2 */
#define SSH2_AGENTC_REQUEST_IDENTITIES 11
#define SSH2_AGENT_IDENTITIES_ANSWER 12
#define SSH2_AGENTC_SIGN_REQUEST 13
#define SSH2_AGENT_SIGN_RESPONSE 14
#define SSH2_AGENTC_ADD_IDENTITY 17
#define SSH2_AGENTC_REMOVE_IDENTITY 18
#define SSH2_AGENTC_REMOVE_ALL_IDENTITIES 19
/* smartcard */
#define SSH_AGENTC_ADD_SMARTCARD_KEY 20
#define SSH_AGENTC_REMOVE_SMARTCARD_KEY 21
/* lock/unlock the agent */
#define SSH_AGENTC_LOCK 22
#define SSH_AGENTC_UNLOCK 23
/* add key with constraints */
#define SSH_AGENTC_ADD_RSA_ID_CONSTRAINED 24
#define SSH2_AGENTC_ADD_ID_CONSTRAINED 25
#define SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED 26
#define SSH_AGENT_CONSTRAIN_LIFETIME 1
#define SSH_AGENT_CONSTRAIN_CONFIRM 2
#define SSH_AGENT_CONSTRAIN_MAXSIGN 3
/* extended failure messages */
#define SSH2_AGENT_FAILURE 30
/* additional error code for ssh.com's ssh-agent2 */
#define SSH_COM_AGENT2_FAILURE 102
#define SSH_AGENT_OLD_SIGNATURE 0x01
#define SSH_AGENT_RSA_SHA2_256 0x02
#define SSH_AGENT_RSA_SHA2_512 0x04
#endif /* AUTHFD_H */