upstream: support for user-verified FIDO keys

FIDO2 supports a notion of "user verification" where the user is
required to demonstrate their identity to the token before particular
operations (e.g. signing). Typically this is done by authenticating
themselves using a PIN that has been set on the token.

This adds support for generating and using user verified keys where
the verification happens via PIN (other options might be added in the
future, but none are in common use now). Practically, this adds
another key generation option "verify-required" that yields a key that
requires a PIN before each authentication.

feedback markus@ and Pedro Martelletto; ok markus@

OpenBSD-Commit-ID: 57fd461e4366f87c47502c5614ec08573e6d6a15

1 files changed, 9 insertions, 7 deletions

diff --git a/sshsig.c b/sshsig.c
index 15f9cead6..658b8c852 100644
--- a/sshsig.c
+++ b/sshsig.c
@@ -151,7 +151,7 @@ done:
 
 static int
 sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
-    const char *sk_provider, const struct sshbuf *h_message,
+    const char *sk_provider, const char *sk_pin, const struct sshbuf *h_message,
     const char *sig_namespace, struct sshbuf **out,
     sshsig_signer *signer, void *signer_ctx)
 {
@@ -185,14 +185,14 @@ sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
         if (signer != NULL) {
                 if ((r = signer(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, sk_provider, 0, signer_ctx)) != 0) {
+                    sign_alg, sk_provider, sk_pin, 0, signer_ctx)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
         } else {
                 if ((r = sshkey_sign(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, sk_provider, 0)) != 0) {
+                    sign_alg, sk_provider, sk_pin, 0)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
@@ -430,7 +430,8 @@ hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_signb(struct sshkey *key, const char *hashalg, const char *sk_provider,
+sshsig_signb(struct sshkey *key, const char *hashalg,
+    const char *sk_provider, const char *sk_pin,
     const struct sshbuf *message, const char *sig_namespace,
     struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
 {
@@ -445,7 +446,7 @@ sshsig_signb(struct sshkey *key, const char *hashalg, const char *sk_provider,
                 error("%s: hash_buffer failed: %s", __func__, ssh_err(r));
                 goto out;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
             sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */
@@ -558,7 +559,8 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_sign_fd(struct sshkey *key, const char *hashalg, const char *sk_provider,
+sshsig_sign_fd(struct sshkey *key, const char *hashalg,
+    const char *sk_provider, const char *sk_pin,
     int fd, const char *sig_namespace, struct sshbuf **out,
     sshsig_signer *signer, void *signer_ctx)
 {
@@ -573,7 +575,7 @@ sshsig_sign_fd(struct sshkey *key, const char *hashalg, const char *sk_provider,
                 error("%s: hash_file failed: %s", __func__, ssh_err(r));
                 return r;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
             sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */