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| author | Matt Johnston <matt@ucc.asn.au> | 2022-03-30 21:06:15 +0800 |
|---|---|---|
| committer | Matt Johnston <matt@ucc.asn.au> | 2022-03-30 21:06:15 +0800 |
| commit | 18eb365ddddb15f280981b3df204524ff057ab0d (patch) | |
| tree | d86ab284bd9c87cb2d72892c09c7358e13993210 | |
| parent | 63335a1db225f7dfd61f8212e19ce3353031a9c5 (diff) | |
| download | dropbear-18eb365ddddb15f280981b3df204524ff057ab0d.tar.gz | |
Handle ecdsa-sk flags, reject no-touch
For the time being Dropbear will only allow SK auth with default
parameters, user-presence needs to be set.
In future handling of authorized_keys option "no-touch-required" can be
added.
This code would also be refactored to share between ecdsa and ed25519
once I get hardware/emulation to test ed25519.
| -rw-r--r-- | sk-ecdsa.c | 9 | ||||
| -rw-r--r-- | sk-ed25519.c | 13 | ||||
| -rw-r--r-- | ssh.h | 5 |
3 files changed, 24 insertions, 3 deletions
@@ -6,6 +6,7 @@ #include "ecc.h" #include "ecdsa.h" #include "sk-ecdsa.h" +#include "ssh.h" int buf_sk_ecdsa_verify(buffer *buf, const ecc_key *key, const buffer *data_buf, const char* app, unsigned int applen) { hash_state hs; @@ -40,6 +41,14 @@ int buf_sk_ecdsa_verify(buffer *buf, const ecc_key *key, const buffer *data_buf, buf_free(sk_buffer); buf_free(sig_buffer); + /* TODO: allow "no-touch-required" or "verify-required" authorized_keys options */ + if (!(flags & SSH_SK_USER_PRESENCE_REQD)) { + if (ret == DROPBEAR_SUCCESS) { + dropbear_log(LOG_WARNING, "Rejecting, user-presence not set"); + } + ret = DROPBEAR_FAILURE; + } + TRACE(("leave buf_sk_ecdsa_verify, ret=%d", ret)) return ret; } diff --git a/sk-ed25519.c b/sk-ed25519.c index 9da9606..902a5e6 100644 --- a/sk-ed25519.c +++ b/sk-ed25519.c @@ -6,6 +6,7 @@ #include "buffer.h" #include "curve25519.h" #include "ed25519.h" +#include "ssh.h" int buf_sk_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const buffer *data_buf, const char* app, unsigned int applen) { @@ -31,6 +32,7 @@ int buf_sk_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const bu flags = buf_getbyte (buf); counter = buf_getint (buf); + /* create the message to be signed */ sk_buffer = buf_new (2*SHA256_HASH_SIZE+5); sha256_init (&hs); sha256_process (&hs, app, applen); @@ -50,10 +52,15 @@ int buf_sk_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const bu ret = DROPBEAR_SUCCESS; } -out: - if (sk_buffer) { - buf_free(sk_buffer); + /* TODO: allow "no-touch-required" or "verify-required" authorized_keys options */ + if (!(flags & SSH_SK_USER_PRESENCE_REQD)) { + if (ret == DROPBEAR_SUCCESS) { + dropbear_log(LOG_WARNING, "Rejecting, user-presence not set"); + } + ret = DROPBEAR_FAILURE; } +out: + buf_free(sk_buffer); TRACE(("leave buf_sk_ed25519_verify: ret %d", ret)) return ret; } @@ -126,3 +126,8 @@ #define SSH2_AGENT_SIGN_RESPONSE 14 #define SSH2_AGENT_FAILURE 30 + +/* Flags defined by OpenSSH U2F key/signature format */ +#define SSH_SK_USER_PRESENCE_REQD 0x01 +#define SSH_SK_USER_VERIFICATION_REQD 0x04 +#define SSH_SK_RESIDENT_KEY 0x20 |