[openssh-commits] [openssh] 02/04: upstream: when refusing a certificate for user authentication, log

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djm pushed a commit to branch master
in repository openssh.

commit 9ffa98111dbe53bf86d07da8e01ded8c5c25456b
Author: djm at openbsd.org <djm at openbsd.org>
AuthorDate: Wed Aug 6 04:53:04 2025 +0000

    upstream: when refusing a certificate for user authentication, log
    
    enough information to identify the certificate in addition to the reason why
    it was being denied. Makes debugging certificate authz problems a bit easier.
    
    ok dlg@
    
    OpenBSD-Commit-ID: 4c4621b2e70412754b3fe7540af8f4bf02b722b1
---
 auth2-hostbased.c  | 14 +++++++++++---
 auth2-pubkey.c     | 12 +++++++++---
 auth2-pubkeyfile.c | 23 ++++++++++++++++-------
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/auth2-hostbased.c b/auth2-hostbased.c
index eb21479a0..e28134a1a 100644
--- a/auth2-hostbased.c
+++ b/auth2-hostbased.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-hostbased.c,v 1.53 2024/05/17 00:30:23 djm Exp $ */
+/* $OpenBSD: auth2-hostbased.c,v 1.54 2025/08/06 04:53:04 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -213,8 +213,16 @@ hostbased_key_allowed(struct ssh *ssh, struct passwd *pw,
 
 	if (sshkey_is_cert(key) &&
 	    sshkey_cert_check_authority_now(key, 1, 0, 0, lookup, &reason)) {
-		error("%s", reason);
-		auth_debug_add("%s", reason);
+		if ((fp = sshkey_fingerprint(key->cert->signature_key,
+		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
+			fatal_f("sshkey_fingerprint fail");
+		error("Refusing certificate ID \"%s\" serial=%llu signed by "
+		    "%s CA %s: %s", key->cert->key_id, key->cert->serial,
+		    sshkey_type(key->cert->signature_key), fp, reason);
+		auth_debug_add("Refused Certificate ID \"%s\" serial=%llu: %s",
+		    key->cert->key_id, (unsigned long long)key->cert->serial,
+		    reason);
+		free(fp);
 		return 0;
 	}
 
diff --git a/auth2-pubkey.c b/auth2-pubkey.c
index aa24fda05..221b242f8 100644
--- a/auth2-pubkey.c
+++ b/auth2-pubkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkey.c,v 1.122 2024/12/12 09:09:09 dtucker Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.123 2025/08/06 04:53:04 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -590,8 +590,14 @@ user_cert_trusted_ca(struct passwd *pw, struct sshkey *key,
 		if ((final_opts = sshauthopt_merge(principals_opts,
 		    cert_opts, &reason)) == NULL) {
  fail_reason:
-			error("%s", reason);
-			auth_debug_add("%s", reason);
+			error("Refusing certificate ID \"%s\" serial=%llu "
+			    "signed by %s CA %s: %s", key->cert->key_id,
+			    key->cert->serial,
+			    sshkey_type(key->cert->signature_key), ca_fp,
+			    reason);
+			auth_debug_add("Refused Certificate ID \"%s\" "
+			    "serial=%llu: %s", key->cert->key_id,
+			    (unsigned long long)key->cert->serial, reason);
 			goto out;
 		}
 	}
diff --git a/auth2-pubkeyfile.c b/auth2-pubkeyfile.c
index 31e7481fb..531a266ac 100644
--- a/auth2-pubkeyfile.c
+++ b/auth2-pubkeyfile.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-pubkeyfile.c,v 1.4 2023/03/05 05:34:09 dtucker Exp $ */
+/* $OpenBSD: auth2-pubkeyfile.c,v 1.5 2025/08/06 04:53:04 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -344,15 +344,15 @@ auth_check_authkey_line(struct passwd *pw, struct sshkey *key,
 	/* Parse and check options present in certificate */
 	if ((certopts = sshauthopt_from_cert(key)) == NULL) {
 		reason = "Invalid certificate options";
-		goto fail_reason;
+		goto cert_fail_reason;
 	}
 	if (auth_authorise_keyopts(pw, certopts, 0,
 	    remote_ip, remote_host, loc) != 0) {
 		reason = "Refused by certificate options";
-		goto fail_reason;
+		goto cert_fail_reason;
 	}
 	if ((finalopts = sshauthopt_merge(keyopts, certopts, &reason)) == NULL)
-		goto fail_reason;
+		goto cert_fail_reason;
 
 	/*
 	 * If the user has specified a list of principals as
@@ -362,12 +362,12 @@ auth_check_authkey_line(struct passwd *pw, struct sshkey *key,
 	if (keyopts->cert_principals != NULL &&
 	    !match_principals_option(keyopts->cert_principals, key->cert)) {
 		reason = "Certificate does not contain an authorized principal";
-		goto fail_reason;
+		goto cert_fail_reason;
 	}
 	if (sshkey_cert_check_authority_now(key, 0, 0, 0,
 	    keyopts->cert_principals == NULL ? pw->pw_name : NULL,
 	    &reason) != 0)
-		goto fail_reason;
+		goto cert_fail_reason;
 
 	verbose("Accepted certificate ID \"%s\" (serial %llu) "
 	    "signed by CA %s %s found at %s",
@@ -386,8 +386,17 @@ auth_check_authkey_line(struct passwd *pw, struct sshkey *key,
 	ret = 0;
 	goto out;
 
+ cert_fail_reason:
+	error("Refusing certificate ID \"%s\" serial=%llu "
+	    "signed by %s CA %s via %s: %s", key->cert->key_id,
+	    key->cert->serial, sshkey_type(key->cert->signature_key),
+	    fp, loc, reason);
+	auth_debug_add("Refused Certificate ID \"%s\" serial=%llu: %s",
+	    key->cert->key_id, (unsigned long long)key->cert->serial, reason);
+	goto out;
+
  fail_reason:
-	error("%s", reason);
+	error("%s at %s", reason, loc);
 	auth_debug_add("%s", reason);
  out:
 	free(fp);

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