upstream: allow key revocation by SHA256 hash and allow ssh-keygen

to create KRLs using SHA256/base64 key fingerprints; ok markus@

OpenBSD-Commit-ID: a0590fd34e7f1141f2873ab3acc57442560e6a94

1 files changed, 67 insertions, 8 deletions

diff --git a/ssh-keygen.c b/ssh-keygen.c
index 22860ad90..748ce37d7 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-keygen.c,v 1.319 2018/08/08 01:16:01 djm Exp $ */
+/* $OpenBSD: ssh-keygen.c,v 1.320 2018/09/12 01:21:34 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2080,15 +2080,51 @@ load_krl(const char *path, struct ssh_krl **krlp)
 }
 
 static void
+hash_to_blob(const char *cp, u_char **blobp, size_t *lenp,
+    const char *file, u_long lnum)
+{
+        char *tmp;
+        size_t tlen;
+        struct sshbuf *b;
+        int r;
+
+        if (strncmp(cp, "SHA256:", 7) != 0)
+                fatal("%s:%lu: unsupported hash algorithm", file, lnum);
+        cp += 7;
+
+        /*
+         * OpenSSH base64 hashes omit trailing '='
+         * characters; put them back for decode.
+         */
+        tlen = strlen(cp);
+        tmp = xmalloc(tlen + 4 + 1);
+        strlcpy(tmp, cp, tlen + 1);
+        while ((tlen % 4) != 0) {
+                tmp[tlen++] = '=';
+                tmp[tlen] = '\0';
+        }
+        if ((b = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_b64tod(b, tmp)) != 0)
+                fatal("%s:%lu: decode hash failed: %s", file, lnum, ssh_err(r));
+        free(tmp);
+        *lenp = sshbuf_len(b);
+        *blobp = xmalloc(*lenp);
+        memcpy(*blobp, sshbuf_ptr(b), *lenp);
+        sshbuf_free(b);
+}
+
+static void
 update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
     const struct sshkey *ca, struct ssh_krl *krl)
 {
         struct sshkey *key = NULL;
         u_long lnum = 0;
         char *path, *cp, *ep, *line = NULL;
-        size_t linesize = 0;
+        u_char *blob = NULL;
+        size_t blen = 0, linesize = 0;
         unsigned long long serial, serial2;
-        int i, was_explicit_key, was_sha1, r;
+        int i, was_explicit_key, was_sha1, was_sha256, was_hash, r;
         FILE *krl_spec;
 
         path = tilde_expand_filename(file, pw->pw_uid);
@@ -2103,7 +2139,7 @@ update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
                 printf("Revoking from %s\n", path);
         while (getline(&line, &linesize, krl_spec) != -1) {
                 lnum++;
-                was_explicit_key = was_sha1 = 0;
+                was_explicit_key = was_sha1 = was_sha256 = was_hash = 0;
                 cp = line + strspn(line, " \t");
                 /* Trim trailing space, comments and strip \n */
                 for (i = 0, r = -1; cp[i] != '\0'; i++) {
@@ -2168,6 +2204,11 @@ update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
                         cp = cp + strspn(cp, " \t");
                         if (ssh_krl_revoke_cert_by_key_id(krl, ca, cp) != 0)
                                 fatal("%s: revoke key ID failed", __func__);
+                } else if (strncasecmp(cp, "hash:", 5) == 0) {
+                        cp += 5;
+                        cp = cp + strspn(cp, " \t");
+                        hash_to_blob(cp, &blob, &blen, file, lnum);
+                        r = ssh_krl_revoke_key_sha256(krl, blob, blen);
                 } else {
                         if (strncasecmp(cp, "key:", 4) == 0) {
                                 cp += 4;
@@ -2177,7 +2218,10 @@ update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
                                 cp += 5;
                                 cp = cp + strspn(cp, " \t");
                                 was_sha1 = 1;
-                        } else {
+                        } else if (strncasecmp(cp, "sha256:", 7) == 0) {
+                                cp += 7;
+                                cp = cp + strspn(cp, " \t");
+                                was_sha256 = 1;
                                 /*
                                  * Just try to process the line as a key.
                                  * Parsing will fail if it isn't.
@@ -2190,13 +2234,28 @@ update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
                                     path, lnum, ssh_err(r));
                         if (was_explicit_key)
                                 r = ssh_krl_revoke_key_explicit(krl, key);
-                        else if (was_sha1)
-                                r = ssh_krl_revoke_key_sha1(krl, key);
-                        else
+                        else if (was_sha1) {
+                                if (sshkey_fingerprint_raw(key,
+                                    SSH_DIGEST_SHA1, &blob, &blen) != 0) {
+                                        fatal("%s:%lu: fingerprint failed",
+                                            file, lnum);
+                                }
+                                r = ssh_krl_revoke_key_sha1(krl, blob, blen);
+                        } else if (was_sha256) {
+                                if (sshkey_fingerprint_raw(key,
+                                    SSH_DIGEST_SHA256, &blob, &blen) != 0) {
+                                        fatal("%s:%lu: fingerprint failed",
+                                            file, lnum);
+                                }
+                                r = ssh_krl_revoke_key_sha256(krl, blob, blen);
+                        } else
                                 r = ssh_krl_revoke_key(krl, key);
                         if (r != 0)
                                 fatal("%s: revoke key failed: %s",
                                     __func__, ssh_err(r));
+                        freezero(blob, blen);
+                        blob = NULL;
+                        blen = 0;
                         sshkey_free(key);
                 }
         }