-/* $OpenBSD: sshconnect.c,v 1.341 2020/10/18 11:32:02 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.342 2020/11/12 22:56:00 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
return 0;
}
+struct find_by_key_ctx {
+ const char *host, *ip;
+ const struct sshkey *key;
+ char **names;
+ u_int nnames;
+};
+
+/* Try to replace home directory prefix (per $HOME) with a ~/ sequence */
+static char *
+try_tilde_unexpand(const char *path)
+{
+ char *home, *ret = NULL;
+ size_t l;
+
+ if (*path != '/')
+ return xstrdup(path);
+ if ((home = getenv("HOME")) == NULL || (l = strlen(home)) == 0)
+ return xstrdup(path);
+ if (strncmp(path, home, l) != 0)
+ return xstrdup(path);
+ /*
+ * ensure we have matched on a path boundary: either the $HOME that
+ * we just compared ends with a '/' or the next character of the path
+ * must be a '/'.
+ */
+ if (home[l - 1] != '/' && path[l] != '/')
+ return xstrdup(path);
+ if (path[l] == '/')
+ l++;
+ xasprintf(&ret, "~/%s", path + l);
+ return ret;
+}
+
+static int
+hostkeys_find_by_key_cb(struct hostkey_foreach_line *l, void *_ctx)
+{
+ struct find_by_key_ctx *ctx = (struct find_by_key_ctx *)_ctx;
+ char *path;
+
+ /* we are looking for keys with names that *do not* match */
+ if ((l->match & HKF_MATCH_HOST) != 0)
+ return 0;
+ /* not interested in marker lines */
+ if (l->marker != MRK_NONE)
+ return 0;
+ /* we are only interested in exact key matches */
+ if (l->key == NULL || !sshkey_equal(ctx->key, l->key))
+ return 0;
+ path = try_tilde_unexpand(l->path);
+ debug_f("found matching key in %s:%lu", path, l->linenum);
+ ctx->names = xrecallocarray(ctx->names,
+ ctx->nnames, ctx->nnames + 1, sizeof(*ctx->names));
+ xasprintf(&ctx->names[ctx->nnames], "%s:%lu: %s", path, l->linenum,
+ strncmp(l->hosts, HASH_MAGIC, strlen(HASH_MAGIC)) == 0 ?
+ "[hashed name]" : l->hosts);
+ ctx->nnames++;
+ free(path);
+ return 0;
+}
+
+static int
+hostkeys_find_by_key_hostfile(const char *file, const char *which,
+ struct find_by_key_ctx *ctx)
+{
+ int r;
+
+ debug3_f("trying %s hostfile \"%s\"", which, file);
+ if ((r = hostkeys_foreach(file, hostkeys_find_by_key_cb, ctx,
+ ctx->host, ctx->ip, HKF_WANT_PARSE_KEY)) != 0) {
+ if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
+ debug_f("hostkeys file %s does not exist", file);
+ return 0;
+ }
+ error_fr(r, "hostkeys_foreach failed for %s", file);
+ return r;
+ }
+ return 0;
+}
+
+/*
+ * Find 'key' in known hosts file(s) that do not match host/ip.
+ * Used to display also-known-as information for previously-unseen hostkeys.
+ */
+static void
+hostkeys_find_by_key(const char *host, const char *ip, const struct sshkey *key,
+ char **user_hostfiles, u_int num_user_hostfiles,
+ char **system_hostfiles, u_int num_system_hostfiles,
+ char ***names, u_int *nnames)
+{
+ struct find_by_key_ctx ctx = {0};
+ u_int i;
+
+ *names = NULL;
+ *nnames = 0;
+
+ if (key == NULL || sshkey_is_cert(key))
+ return;
+
+ ctx.host = host;
+ ctx.ip = ip;
+ ctx.key = key;
+
+ for (i = 0; i < num_user_hostfiles; i++) {
+ if (hostkeys_find_by_key_hostfile(user_hostfiles[i],
+ "user", &ctx) != 0)
+ goto fail;
+ }
+ for (i = 0; i < num_system_hostfiles; i++) {
+ if (hostkeys_find_by_key_hostfile(system_hostfiles[i],
+ "system", &ctx) != 0)
+ goto fail;
+ }
+ /* success */
+ *names = ctx.names;
+ *nnames = ctx.nnames;
+ ctx.names = NULL;
+ ctx.nnames = 0;
+ return;
+ fail:
+ for (i = 0; i < ctx.nnames; i++)
+ free(ctx.names[i]);
+ free(ctx.names);
+}
+
+#define MAX_OTHER_NAMES 8 /* Maximum number of names to list */
+static char *
+other_hostkeys_message(const char *host, const char *ip,
+ const struct sshkey *key,
+ char **user_hostfiles, u_int num_user_hostfiles,
+ char **system_hostfiles, u_int num_system_hostfiles)
+{
+ char *ret = NULL, **othernames = NULL;
+ u_int i, n, num_othernames = 0;
+
+ hostkeys_find_by_key(host, ip, key,
+ user_hostfiles, num_user_hostfiles,
+ system_hostfiles, num_system_hostfiles,
+ &othernames, &num_othernames);
+ if (num_othernames == 0)
+ return xstrdup("This key is not known by any other names");
+
+ xasprintf(&ret, "This host key is known by the following other "
+ "names/addresses:");
+
+ n = num_othernames;
+ if (n > MAX_OTHER_NAMES)
+ n = MAX_OTHER_NAMES;
+ for (i = 0; i < n; i++) {
+ xextendf(&ret, "\n", " %s", othernames[i]);
+ }
+ if (n < num_othernames) {
+ xextendf(&ret, "\n", " (%d additional names ommitted)",
+ num_othernames - n);
+ }
+ for (i = 0; i < num_othernames; i++)
+ free(othernames[i]);
+ free(othernames);
+ return ret;
+}
+
/*
* check whether the supplied host key is valid, return -1 if the key
* is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
goto fail;
} else if (options.strict_host_key_checking ==
SSH_STRICT_HOSTKEY_ASK) {
- char msg1[1024], msg2[1024];
+ char *msg1 = NULL, *msg2 = NULL;
+
+ xasprintf(&msg1, "The authenticity of host "
+ "'%.200s (%s)' can't be established", host, ip);
+
+ if (show_other_keys(host_hostkeys, host_key)) {
+ xextendf(&msg1, "\n", "but keys of different "
+ "type are already known for this host.");
+ } else
+ xextendf(&msg1, "", ".");
- if (show_other_keys(host_hostkeys, host_key))
- snprintf(msg1, sizeof(msg1),
- "\nbut keys of different type are already"
- " known for this host.");
- else
- snprintf(msg1, sizeof(msg1), ".");
- /* The default */
fp = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_DEFAULT);
ra = sshkey_fingerprint(host_key,
options.fingerprint_hash, SSH_FP_RANDOMART);
if (fp == NULL || ra == NULL)
fatal_f("sshkey_fingerprint failed");
- msg2[0] = '\0';
+ xextendf(&msg1, "\n", "%s key fingerprint is %s.",
+ type, fp);
+ if (options.visual_host_key)
+ xextendf(&msg1, "\n", "%s", ra);
if (options.verify_host_key_dns) {
- if (matching_host_key_dns)
- snprintf(msg2, sizeof(msg2),
- "Matching host key fingerprint"
- " found in DNS.\n");
- else
- snprintf(msg2, sizeof(msg2),
- "No matching host key fingerprint"
- " found in DNS.\n");
+ xextendf(&msg1, "\n",
+ "%s host key fingerprint found in DNS.",
+ matching_host_key_dns ?
+ "Matching" : "No matching");
}
- snprintf(msg, sizeof(msg),
- "The authenticity of host '%.200s (%s)' can't be "
- "established%s\n"
- "%s key fingerprint is %s.%s%s\n%s"
+ /* msg2 informs for other names matching this key */
+ if ((msg2 = other_hostkeys_message(host, ip, host_key,
+ user_hostfiles, num_user_hostfiles,
+ system_hostfiles, num_system_hostfiles)) != NULL)
+ xextendf(&msg1, "\n", "%s", msg2);
+
+ xextendf(&msg1, "\n",
"Are you sure you want to continue connecting "
- "(yes/no/[fingerprint])? ",
- host, ip, msg1, type, fp,
- options.visual_host_key ? "\n" : "",
- options.visual_host_key ? ra : "",
- msg2);
+ "(yes/no/[fingerprint])? ");
+
+ confirmed = confirm(msg1, fp);
free(ra);
- confirmed = confirm(msg, fp);
free(fp);
+ free(msg1);
+ free(msg2);
if (!confirmed)
goto fail;
hostkey_trusted = 1; /* user explicitly confirmed */
projects / thirdparty / openssh-portable.git / commitdiff
