From: djm <djm@openbsd.org>
Date: Thu, 6 Jan 2022 22:05:42 +0000 (+0000)
Subject: add a helper function to match a key type to a list of signature
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=661a795ce3c4e4c6f33de3f542701e7c54ad7d17;p=openbsd

add a helper function to match a key type to a list of signature
algorithms. RSA keys can make signatures with multiple algorithms,
so some special handling is required.
ok markus@
---

diff --git a/usr.bin/ssh/sshkey.c b/usr.bin/ssh/sshkey.c
index 193f6ec11ff..cdc29e586a4 100644
--- a/usr.bin/ssh/sshkey.c
+++ b/usr.bin/ssh/sshkey.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.c,v 1.119 2021/07/23 03:37:52 djm Exp $ */
+/* $OpenBSD: sshkey.c,v 1.120 2022/01/06 22:05:42 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Alexander von Gernler.  All rights reserved.
@@ -234,6 +234,29 @@ sshkey_ecdsa_nid_from_name(const char *name)
 	return -1;
 }
 
+int
+sshkey_match_keyname_to_sigalgs(const char *keyname, const char *sigalgs)
+{
+	int ktype;
+
+	if (sigalgs == NULL || *sigalgs == '\0' ||
+	    (ktype = sshkey_type_from_name(keyname)) == KEY_UNSPEC)
+		return 0;
+	else if (ktype == KEY_RSA) {
+		return match_pattern_list("ssh-rsa", sigalgs, 0) == 1 ||
+		    match_pattern_list("rsa-sha2-256", sigalgs, 0) == 1 ||
+		    match_pattern_list("rsa-sha2-512", sigalgs, 0) == 1;
+	} else if (ktype == KEY_RSA_CERT) {
+		return match_pattern_list("ssh-rsa-cert-v01@openssh.com",
+		    sigalgs, 0) == 1 ||
+		    match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
+		    sigalgs, 0) == 1 ||
+		    match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
+		    sigalgs, 0) == 1;
+	} else
+		return match_pattern_list(keyname, sigalgs, 0) == 1;
+}
+
 char *
 sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep)
 {
diff --git a/usr.bin/ssh/sshkey.h b/usr.bin/ssh/sshkey.h
index ecae86e8eb7..125cadb64df 100644
--- a/usr.bin/ssh/sshkey.h
+++ b/usr.bin/ssh/sshkey.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshkey.h,v 1.50 2021/07/23 03:37:52 djm Exp $ */
+/* $OpenBSD: sshkey.h,v 1.51 2022/01/06 22:05:42 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -186,6 +186,10 @@ int	 sshkey_is_cert(const struct sshkey *);
 int	 sshkey_is_sk(const struct sshkey *);
 int	 sshkey_type_is_cert(int);
 int	 sshkey_type_plain(int);
+
+/* Returns non-zero if key name match sigalgs pattern list. (handles RSA) */
+int	 sshkey_match_keyname_to_sigalgs(const char *, const char *);
+
 int	 sshkey_to_certified(struct sshkey *);
 int	 sshkey_drop_cert(struct sshkey *);
 int	 sshkey_cert_copy(const struct sshkey *, struct sshkey *);