Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 937 insertions, 0 deletions

diff --git a/hostfile.c b/hostfile.c
new file mode 100644
index 0000000..bd49e3a
--- /dev/null
+++ b/hostfile.c
@@ -0,0 +1,937 @@
+/* $OpenBSD: hostfile.c,v 1.93 2022/01/06 22:02:52 djm Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Functions for manipulating the known hosts files.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ *
+ * Copyright (c) 1999, 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 1999 Niels Provos.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <netinet/in.h>
+
+#include <errno.h>
+#include <resolv.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "xmalloc.h"
+#include "match.h"
+#include "sshkey.h"
+#include "hostfile.h"
+#include "log.h"
+#include "misc.h"
+#include "pathnames.h"
+#include "ssherr.h"
+#include "digest.h"
+#include "hmac.h"
+#include "sshbuf.h"
+
+/* XXX hmac is too easy to dictionary attack; use bcrypt? */
+
+static int
+extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len)
+{
+	char *p, *b64salt;
+	u_int b64len;
+	int ret;
+
+	if (l < sizeof(HASH_MAGIC) - 1) {
+		debug2("extract_salt: string too short");
+		return (-1);
+	}
+	if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
+		debug2("extract_salt: invalid magic identifier");
+		return (-1);
+	}
+	s += sizeof(HASH_MAGIC) - 1;
+	l -= sizeof(HASH_MAGIC) - 1;
+	if ((p = memchr(s, HASH_DELIM, l)) == NULL) {
+		debug2("extract_salt: missing salt termination character");
+		return (-1);
+	}
+
+	b64len = p - s;
+	/* Sanity check */
+	if (b64len == 0 || b64len > 1024) {
+		debug2("extract_salt: bad encoded salt length %u", b64len);
+		return (-1);
+	}
+	b64salt = xmalloc(1 + b64len);
+	memcpy(b64salt, s, b64len);
+	b64salt[b64len] = '\0';
+
+	ret = __b64_pton(b64salt, salt, salt_len);
+	free(b64salt);
+	if (ret == -1) {
+		debug2("extract_salt: salt decode error");
+		return (-1);
+	}
+	if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) {
+		debug2("extract_salt: expected salt len %zd, got %d",
+		    ssh_hmac_bytes(SSH_DIGEST_SHA1), ret);
+		return (-1);
+	}
+
+	return (0);
+}
+
+char *
+host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
+{
+	struct ssh_hmac_ctx *ctx;
+	u_char salt[256], result[256];
+	char uu_salt[512], uu_result[512];
+	char *encoded = NULL;
+	u_int len;
+
+	len = ssh_digest_bytes(SSH_DIGEST_SHA1);
+
+	if (name_from_hostfile == NULL) {
+		/* Create new salt */
+		arc4random_buf(salt, len);
+	} else {
+		/* Extract salt from known host entry */
+		if (extract_salt(name_from_hostfile, src_len, salt,
+		    sizeof(salt)) == -1)
+			return (NULL);
+	}
+
+	if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL ||
+	    ssh_hmac_init(ctx, salt, len) < 0 ||
+	    ssh_hmac_update(ctx, host, strlen(host)) < 0 ||
+	    ssh_hmac_final(ctx, result, sizeof(result)))
+		fatal_f("ssh_hmac failed");
+	ssh_hmac_free(ctx);
+
+	if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 ||
+	    __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1)
+		fatal_f("__b64_ntop failed");
+	xasprintf(&encoded, "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM,
+	    uu_result);
+
+	return (encoded);
+}
+
+/*
+ * Parses an RSA (number of bits, e, n) or DSA key from a string.  Moves the
+ * pointer over the key.  Skips any whitespace at the beginning and at end.
+ */
+
+int
+hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret)
+{
+	char *cp;
+
+	/* Skip leading whitespace. */
+	for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
+		;
+
+	if (sshkey_read(ret, &cp) != 0)
+		return 0;
+
+	/* Skip trailing whitespace. */
+	for (; *cp == ' ' || *cp == '\t'; cp++)
+		;
+
+	/* Return results. */
+	*cpp = cp;
+	if (bitsp != NULL)
+		*bitsp = sshkey_size(ret);
+	return 1;
+}
+
+static HostkeyMarker
+check_markers(char **cpp)
+{
+	char marker[32], *sp, *cp = *cpp;
+	int ret = MRK_NONE;
+
+	while (*cp == '@') {
+		/* Only one marker is allowed */
+		if (ret != MRK_NONE)
+			return MRK_ERROR;
+		/* Markers are terminated by whitespace */
+		if ((sp = strchr(cp, ' ')) == NULL &&
+		    (sp = strchr(cp, '\t')) == NULL)
+			return MRK_ERROR;
+		/* Extract marker for comparison */
+		if (sp <= cp + 1 || sp >= cp + sizeof(marker))
+			return MRK_ERROR;
+		memcpy(marker, cp, sp - cp);
+		marker[sp - cp] = '\0';
+		if (strcmp(marker, CA_MARKER) == 0)
+			ret = MRK_CA;
+		else if (strcmp(marker, REVOKE_MARKER) == 0)
+			ret = MRK_REVOKE;
+		else
+			return MRK_ERROR;
+
+		/* Skip past marker and any whitespace that follows it */
+		cp = sp;
+		for (; *cp == ' ' || *cp == '\t'; cp++)
+			;
+	}
+	*cpp = cp;
+	return ret;
+}
+
+struct hostkeys *
+init_hostkeys(void)
+{
+	struct hostkeys *ret = xcalloc(1, sizeof(*ret));
+
+	ret->entries = NULL;
+	return ret;
+}
+
+struct load_callback_ctx {
+	const char *host;
+	u_long num_loaded;
+	struct hostkeys *hostkeys;
+};
+
+static int
+record_hostkey(struct hostkey_foreach_line *l, void *_ctx)
+{
+	struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx;
+	struct hostkeys *hostkeys = ctx->hostkeys;
+	struct hostkey_entry *tmp;
+
+	if (l->status == HKF_STATUS_INVALID) {
+		/* XXX make this verbose() in the future */
+		debug("%s:%ld: parse error in hostkeys file",
+		    l->path, l->linenum);
+		return 0;
+	}
+
+	debug3_f("found %skey type %s in file %s:%lu",
+	    l->marker == MRK_NONE ? "" :
+	    (l->marker == MRK_CA ? "ca " : "revoked "),
+	    sshkey_type(l->key), l->path, l->linenum);
+	if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries,
+	    hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	hostkeys->entries = tmp;
+	hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host);
+	hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path);
+	hostkeys->entries[hostkeys->num_entries].line = l->linenum;
+	hostkeys->entries[hostkeys->num_entries].key = l->key;
+	l->key = NULL; /* steal it */
+	hostkeys->entries[hostkeys->num_entries].marker = l->marker;
+	hostkeys->entries[hostkeys->num_entries].note = l->note;
+	hostkeys->num_entries++;
+	ctx->num_loaded++;
+
+	return 0;
+}
+
+void
+load_hostkeys_file(struct hostkeys *hostkeys, const char *host,
+    const char *path, FILE *f, u_int note)
+{
+	int r;
+	struct load_callback_ctx ctx;
+
+	ctx.host = host;
+	ctx.num_loaded = 0;
+	ctx.hostkeys = hostkeys;
+
+	if ((r = hostkeys_foreach_file(path, f, record_hostkey, &ctx, host,
+	    NULL, HKF_WANT_MATCH|HKF_WANT_PARSE_KEY, note)) != 0) {
+		if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT)
+			debug_fr(r, "hostkeys_foreach failed for %s", path);
+	}
+	if (ctx.num_loaded != 0)
+		debug3_f("loaded %lu keys from %s", ctx.num_loaded, host);
+}
+
+void
+load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path,
+    u_int note)
+{
+	FILE *f;
+
+	if ((f = fopen(path, "r")) == NULL) {
+		debug_f("fopen %s: %s", path, strerror(errno));
+		return;
+	}
+
+	load_hostkeys_file(hostkeys, host, path, f, note);
+	fclose(f);
+}
+
+void
+free_hostkeys(struct hostkeys *hostkeys)
+{
+	u_int i;
+
+	for (i = 0; i < hostkeys->num_entries; i++) {
+		free(hostkeys->entries[i].host);
+		free(hostkeys->entries[i].file);
+		sshkey_free(hostkeys->entries[i].key);
+		explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries));
+	}
+	free(hostkeys->entries);
+	freezero(hostkeys, sizeof(*hostkeys));
+}
+
+static int
+check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k)
+{
+	int is_cert = sshkey_is_cert(k);
+	u_int i;
+
+	for (i = 0; i < hostkeys->num_entries; i++) {
+		if (hostkeys->entries[i].marker != MRK_REVOKE)
+			continue;
+		if (sshkey_equal_public(k, hostkeys->entries[i].key))
+			return -1;
+		if (is_cert && k != NULL &&
+		    sshkey_equal_public(k->cert->signature_key,
+		    hostkeys->entries[i].key))
+			return -1;
+	}
+	return 0;
+}
+
+/*
+ * Match keys against a specified key, or look one up by key type.
+ *
+ * If looking for a keytype (key == NULL) and one is found then return
+ * HOST_FOUND, otherwise HOST_NEW.
+ *
+ * If looking for a key (key != NULL):
+ *  1. If the key is a cert and a matching CA is found, return HOST_OK
+ *  2. If the key is not a cert and a matching key is found, return HOST_OK
+ *  3. If no key matches but a key with a different type is found, then
+ *     return HOST_CHANGED
+ *  4. If no matching keys are found, then return HOST_NEW.
+ *
+ * Finally, check any found key is not revoked.
+ */
+static HostStatus
+check_hostkeys_by_key_or_type(struct hostkeys *hostkeys,
+    struct sshkey *k, int keytype, int nid, const struct hostkey_entry **found)
+{
+	u_int i;
+	HostStatus end_return = HOST_NEW;
+	int want_cert = sshkey_is_cert(k);
+	HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE;
+
+	if (found != NULL)
+		*found = NULL;
+
+	for (i = 0; i < hostkeys->num_entries; i++) {
+		if (hostkeys->entries[i].marker != want_marker)
+			continue;
+		if (k == NULL) {
+			if (hostkeys->entries[i].key->type != keytype)
+				continue;
+			if (nid != -1 &&
+			    sshkey_type_plain(keytype) == KEY_ECDSA &&
+			    hostkeys->entries[i].key->ecdsa_nid != nid)
+				continue;
+			end_return = HOST_FOUND;
+			if (found != NULL)
+				*found = hostkeys->entries + i;
+			k = hostkeys->entries[i].key;
+			break;
+		}
+		if (want_cert) {
+			if (sshkey_equal_public(k->cert->signature_key,
+			    hostkeys->entries[i].key)) {
+				/* A matching CA exists */
+				end_return = HOST_OK;
+				if (found != NULL)
+					*found = hostkeys->entries + i;
+				break;
+			}
+		} else {
+			if (sshkey_equal(k, hostkeys->entries[i].key)) {
+				end_return = HOST_OK;
+				if (found != NULL)
+					*found = hostkeys->entries + i;
+				break;
+			}
+			/* A non-matching key exists */
+			end_return = HOST_CHANGED;
+			if (found != NULL)
+				*found = hostkeys->entries + i;
+		}
+	}
+	if (check_key_not_revoked(hostkeys, k) != 0) {
+		end_return = HOST_REVOKED;
+		if (found != NULL)
+			*found = NULL;
+	}
+	return end_return;
+}
+
+HostStatus
+check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key,
+    const struct hostkey_entry **found)
+{
+	if (key == NULL)
+		fatal("no key to look up");
+	return check_hostkeys_by_key_or_type(hostkeys, key, 0, -1, found);
+}
+
+int
+lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype, int nid,
+    const struct hostkey_entry **found)
+{
+	return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype, nid,
+	    found) == HOST_FOUND);
+}
+
+int
+lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker)
+{
+	u_int i;
+
+	for (i = 0; i < hostkeys->num_entries; i++) {
+		if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker)
+			return 1;
+	}
+	return 0;
+}
+
+static int
+write_host_entry(FILE *f, const char *host, const char *ip,
+    const struct sshkey *key, int store_hash)
+{
+	int r, success = 0;
+	char *hashed_host = NULL, *lhost;
+
+	lhost = xstrdup(host);
+	lowercase(lhost);
+
+	if (store_hash) {
+		if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) {
+			error_f("host_hash failed");
+			free(lhost);
+			return 0;
+		}
+		fprintf(f, "%s ", hashed_host);
+	} else if (ip != NULL)
+		fprintf(f, "%s,%s ", lhost, ip);
+	else {
+		fprintf(f, "%s ", lhost);
+	}
+	free(hashed_host);
+	free(lhost);
+	if ((r = sshkey_write(key, f)) == 0)
+		success = 1;
+	else
+		error_fr(r, "sshkey_write");
+	fputc('\n', f);
+	/* If hashing is enabled, the IP address needs to go on its own line */
+	if (success && store_hash && ip != NULL)
+		success = write_host_entry(f, ip, NULL, key, 1);
+	return success;
+}
+
+/*
+ * Create user ~/.ssh directory if it doesn't exist and we want to write to it.
+ * If notify is set, a message will be emitted if the directory is created.
+ */
+void
+hostfile_create_user_ssh_dir(const char *filename, int notify)
+{
+	char *dotsshdir = NULL, *p;
+	size_t len;
+	struct stat st;
+
+	if ((p = strrchr(filename, '/')) == NULL)
+		return;
+	len = p - filename;
+	dotsshdir = tilde_expand_filename("~/" _PATH_SSH_USER_DIR, getuid());
+	if (strlen(dotsshdir) > len || strncmp(filename, dotsshdir, len) != 0)
+		goto out; /* not ~/.ssh prefixed */
+	if (stat(dotsshdir, &st) == 0)
+		goto out; /* dir already exists */
+	else if (errno != ENOENT)
+		error("Could not stat %s: %s", dotsshdir, strerror(errno));
+	else {
+#ifdef WITH_SELINUX
+		ssh_selinux_setfscreatecon(dotsshdir);
+#endif
+		if (mkdir(dotsshdir, 0700) == -1)
+			error("Could not create directory '%.200s' (%s).",
+			    dotsshdir, strerror(errno));
+		else if (notify)
+			logit("Created directory '%s'.", dotsshdir);
+#ifdef WITH_SELINUX
+		ssh_selinux_setfscreatecon(NULL);
+#endif
+	}
+ out:
+	free(dotsshdir);
+}
+
+/*
+ * Appends an entry to the host file.  Returns false if the entry could not
+ * be appended.
+ */
+int
+add_host_to_hostfile(const char *filename, const char *host,
+    const struct sshkey *key, int store_hash)
+{
+	FILE *f;
+	int success;
+
+	if (key == NULL)
+		return 1;	/* XXX ? */
+	hostfile_create_user_ssh_dir(filename, 0);
+	f = fopen(filename, "a");
+	if (!f)
+		return 0;
+	success = write_host_entry(f, host, NULL, key, store_hash);
+	fclose(f);
+	return success;
+}
+
+struct host_delete_ctx {
+	FILE *out;
+	int quiet;
+	const char *host, *ip;
+	u_int *match_keys;	/* mask of HKF_MATCH_* for this key */
+	struct sshkey * const *keys;
+	size_t nkeys;
+	int modified;
+};
+
+static int
+host_delete(struct hostkey_foreach_line *l, void *_ctx)
+{
+	struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx;
+	int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
+	size_t i;
+
+	/* Don't remove CA and revocation lines */
+	if (l->status == HKF_STATUS_MATCHED && l->marker == MRK_NONE) {
+		/*
+		 * If this line contains one of the keys that we will be
+		 * adding later, then don't change it and mark the key for
+		 * skipping.
+		 */
+		for (i = 0; i < ctx->nkeys; i++) {
+			if (!sshkey_equal(ctx->keys[i], l->key))
+				continue;
+			ctx->match_keys[i] |= l->match;
+			fprintf(ctx->out, "%s\n", l->line);
+			debug3_f("%s key already at %s:%ld",
+			    sshkey_type(l->key), l->path, l->linenum);
+			return 0;
+		}
+
+		/*
+		 * Hostname matches and has no CA/revoke marker, delete it
+		 * by *not* writing the line to ctx->out.
+		 */
+		do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s",
+		    ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
+		    l->path, l->linenum, sshkey_type(l->key), ctx->host);
+		ctx->modified = 1;
+		return 0;
+	}
+	/* Retain non-matching hosts and invalid lines when deleting */
+	if (l->status == HKF_STATUS_INVALID) {
+		do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry",
+		    ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
+		    l->path, l->linenum);
+	}
+	fprintf(ctx->out, "%s\n", l->line);
+	return 0;
+}
+
+int
+hostfile_replace_entries(const char *filename, const char *host, const char *ip,
+    struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg)
+{
+	int r, fd, oerrno = 0;
+	int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
+	struct host_delete_ctx ctx;
+	char *fp, *temp = NULL, *back = NULL;
+	const char *what;
+	mode_t omask;
+	size_t i;
+	u_int want;
+
+	omask = umask(077);
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.host = host;
+	ctx.ip = ip;
+	ctx.quiet = quiet;
+
+	if ((ctx.match_keys = calloc(nkeys, sizeof(*ctx.match_keys))) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	ctx.keys = keys;
+	ctx.nkeys = nkeys;
+	ctx.modified = 0;
+
+	/*
+	 * Prepare temporary file for in-place deletion.
+	 */
+	if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) == -1 ||
+	    (r = asprintf(&back, "%s.old", filename)) == -1) {
+		r = SSH_ERR_ALLOC_FAIL;
+		goto fail;
+	}
+
+	if ((fd = mkstemp(temp)) == -1) {
+		oerrno = errno;
+		error_f("mkstemp: %s", strerror(oerrno));
+		r = SSH_ERR_SYSTEM_ERROR;
+		goto fail;
+	}
+	if ((ctx.out = fdopen(fd, "w")) == NULL) {
+		oerrno = errno;
+		close(fd);
+		error_f("fdopen: %s", strerror(oerrno));
+		r = SSH_ERR_SYSTEM_ERROR;
+		goto fail;
+	}
+
+	/* Remove stale/mismatching entries for the specified host */
+	if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip,
+	    HKF_WANT_PARSE_KEY, 0)) != 0) {
+		oerrno = errno;
+		error_fr(r, "hostkeys_foreach");
+		goto fail;
+	}
+
+	/* Re-add the requested keys */
+	want = HKF_MATCH_HOST | (ip == NULL ? 0 : HKF_MATCH_IP);
+	for (i = 0; i < nkeys; i++) {
+		if (keys[i] == NULL || (want & ctx.match_keys[i]) == want)
+			continue;
+		if ((fp = sshkey_fingerprint(keys[i], hash_alg,
+		    SSH_FP_DEFAULT)) == NULL) {
+			r = SSH_ERR_ALLOC_FAIL;
+			goto fail;
+		}
+		/* write host/ip */
+		what = "";
+		if (ctx.match_keys[i] == 0) {
+			what = "Adding new key";
+			if (!write_host_entry(ctx.out, host, ip,
+			    keys[i], store_hash)) {
+				r = SSH_ERR_INTERNAL_ERROR;
+				goto fail;
+			}
+		} else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_HOST) {
+			what = "Fixing match (hostname)";
+			if (!write_host_entry(ctx.out, host, NULL,
+			    keys[i], store_hash)) {
+				r = SSH_ERR_INTERNAL_ERROR;
+				goto fail;
+			}
+		} else if ((want & ~ctx.match_keys[i]) == HKF_MATCH_IP) {
+			what = "Fixing match (address)";
+			if (!write_host_entry(ctx.out, ip, NULL,
+			    keys[i], store_hash)) {
+				r = SSH_ERR_INTERNAL_ERROR;
+				goto fail;
+			}
+		}
+		do_log2(loglevel, "%s%s%s for %s%s%s to %s: %s %s",
+		    quiet ? __func__ : "", quiet ? ": " : "", what,
+		    host, ip == NULL ? "" : ",", ip == NULL ? "" : ip, filename,
+		    sshkey_ssh_name(keys[i]), fp);
+		free(fp);
+		ctx.modified = 1;
+	}
+	fclose(ctx.out);
+	ctx.out = NULL;
+
+	if (ctx.modified) {
+		/* Backup the original file and replace it with the temporary */
+		if (unlink(back) == -1 && errno != ENOENT) {
+			oerrno = errno;
+			error_f("unlink %.100s: %s", back, strerror(errno));
+			r = SSH_ERR_SYSTEM_ERROR;
+			goto fail;
+		}
+		if (link(filename, back) == -1) {
+			oerrno = errno;
+			error_f("link %.100s to %.100s: %s", filename,
+			    back, strerror(errno));
+			r = SSH_ERR_SYSTEM_ERROR;
+			goto fail;
+		}
+		if (rename(temp, filename) == -1) {
+			oerrno = errno;
+			error_f("rename \"%s\" to \"%s\": %s", temp,
+			    filename, strerror(errno));
+			r = SSH_ERR_SYSTEM_ERROR;
+			goto fail;
+		}
+	} else {
+		/* No changes made; just delete the temporary file */
+		if (unlink(temp) != 0)
+			error_f("unlink \"%s\": %s", temp, strerror(errno));
+	}
+
+	/* success */
+	r = 0;
+ fail:
+	if (temp != NULL && r != 0)
+		unlink(temp);
+	free(temp);
+	free(back);
+	if (ctx.out != NULL)
+		fclose(ctx.out);
+	free(ctx.match_keys);
+	umask(omask);
+	if (r == SSH_ERR_SYSTEM_ERROR)
+		errno = oerrno;
+	return r;
+}
+
+static int
+match_maybe_hashed(const char *host, const char *names, int *was_hashed)
+{
+	int hashed = *names == HASH_DELIM, ret;
+	char *hashed_host = NULL;
+	size_t nlen = strlen(names);
+
+	if (was_hashed != NULL)
+		*was_hashed = hashed;
+	if (hashed) {
+		if ((hashed_host = host_hash(host, names, nlen)) == NULL)
+			return -1;
+		ret = (nlen == strlen(hashed_host) &&
+		    strncmp(hashed_host, names, nlen) == 0);
+		free(hashed_host);
+		return ret;
+	}
+	return match_hostname(host, names) == 1;
+}
+
+int
+hostkeys_foreach_file(const char *path, FILE *f, hostkeys_foreach_fn *callback,
+    void *ctx, const char *host, const char *ip, u_int options, u_int note)
+{
+	char *line = NULL, ktype[128];
+	u_long linenum = 0;
+	char *cp, *cp2;
+	u_int kbits;
+	int hashed;
+	int s, r = 0;
+	struct hostkey_foreach_line lineinfo;
+	size_t linesize = 0, l;
+
+	memset(&lineinfo, 0, sizeof(lineinfo));
+	if (host == NULL && (options & HKF_WANT_MATCH) != 0)
+		return SSH_ERR_INVALID_ARGUMENT;
+
+	while (getline(&line, &linesize, f) != -1) {
+		linenum++;
+		line[strcspn(line, "\n")] = '\0';
+
+		free(lineinfo.line);
+		sshkey_free(lineinfo.key);
+		memset(&lineinfo, 0, sizeof(lineinfo));
+		lineinfo.path = path;
+		lineinfo.linenum = linenum;
+		lineinfo.line = xstrdup(line);
+		lineinfo.marker = MRK_NONE;
+		lineinfo.status = HKF_STATUS_OK;
+		lineinfo.keytype = KEY_UNSPEC;
+		lineinfo.note = note;
+
+		/* Skip any leading whitespace, comments and empty lines. */
+		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
+			;
+		if (!*cp || *cp == '#' || *cp == '\n') {
+			if ((options & HKF_WANT_MATCH) == 0) {
+				lineinfo.status = HKF_STATUS_COMMENT;
+				if ((r = callback(&lineinfo, ctx)) != 0)
+					break;
+			}
+			continue;
+		}
+
+		if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) {
+			verbose_f("invalid marker at %s:%lu", path, linenum);
+			if ((options & HKF_WANT_MATCH) == 0)
+				goto bad;
+			continue;
+		}
+
+		/* Find the end of the host name portion. */
+		for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
+			;
+		lineinfo.hosts = cp;
+		*cp2++ = '\0';
+
+		/* Check if the host name matches. */
+		if (host != NULL) {
+			if ((s = match_maybe_hashed(host, lineinfo.hosts,
+			    &hashed)) == -1) {
+				debug2_f("%s:%ld: bad host hash \"%.32s\"",
+				    path, linenum, lineinfo.hosts);
+				goto bad;
+			}
+			if (s == 1) {
+				lineinfo.status = HKF_STATUS_MATCHED;
+				lineinfo.match |= HKF_MATCH_HOST |
+				    (hashed ? HKF_MATCH_HOST_HASHED : 0);
+			}
+			/* Try matching IP address if supplied */
+			if (ip != NULL) {
+				if ((s = match_maybe_hashed(ip, lineinfo.hosts,
+				    &hashed)) == -1) {
+					debug2_f("%s:%ld: bad ip hash "
+					    "\"%.32s\"", path, linenum,
+					    lineinfo.hosts);
+					goto bad;
+				}
+				if (s == 1) {
+					lineinfo.status = HKF_STATUS_MATCHED;
+					lineinfo.match |= HKF_MATCH_IP |
+					    (hashed ? HKF_MATCH_IP_HASHED : 0);
+				}
+			}
+			/*
+			 * Skip this line if host matching requested and
+			 * neither host nor address matched.
+			 */
+			if ((options & HKF_WANT_MATCH) != 0 &&
+			    lineinfo.status != HKF_STATUS_MATCHED)
+				continue;
+		}
+
+		/* Got a match.  Skip host name and any following whitespace */
+		for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
+			;
+		if (*cp2 == '\0' || *cp2 == '#') {
+			debug2("%s:%ld: truncated before key type",
+			    path, linenum);
+			goto bad;
+		}
+		lineinfo.rawkey = cp = cp2;
+
+		if ((options & HKF_WANT_PARSE_KEY) != 0) {
+			/*
+			 * Extract the key from the line.  This will skip
+			 * any leading whitespace.  Ignore badly formatted
+			 * lines.
+			 */
+			if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) {
+				error_f("sshkey_new failed");
+				r = SSH_ERR_ALLOC_FAIL;
+				break;
+			}
+			if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) {
+				goto bad;
+			}
+			lineinfo.keytype = lineinfo.key->type;
+			lineinfo.comment = cp;
+		} else {
+			/* Extract and parse key type */
+			l = strcspn(lineinfo.rawkey, " \t");
+			if (l <= 1 || l >= sizeof(ktype) ||
+			    lineinfo.rawkey[l] == '\0')
+				goto bad;
+			memcpy(ktype, lineinfo.rawkey, l);
+			ktype[l] = '\0';
+			lineinfo.keytype = sshkey_type_from_name(ktype);
+
+			/*
+			 * Assume legacy RSA1 if the first component is a short
+			 * decimal number.
+			 */
+			if (lineinfo.keytype == KEY_UNSPEC && l < 8 &&
+			    strspn(ktype, "0123456789") == l)
+				goto bad;
+
+			/*
+			 * Check that something other than whitespace follows
+			 * the key type. This won't catch all corruption, but
+			 * it does catch trivial truncation.
+			 */
+			cp2 += l; /* Skip past key type */
+			for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
+				;
+			if (*cp2 == '\0' || *cp2 == '#') {
+				debug2("%s:%ld: truncated after key type",
+				    path, linenum);
+				lineinfo.keytype = KEY_UNSPEC;
+			}
+			if (lineinfo.keytype == KEY_UNSPEC) {
+ bad:
+				sshkey_free(lineinfo.key);
+				lineinfo.key = NULL;
+				lineinfo.status = HKF_STATUS_INVALID;
+				if ((r = callback(&lineinfo, ctx)) != 0)
+					break;
+				continue;
+			}
+		}
+		if ((r = callback(&lineinfo, ctx)) != 0)
+			break;
+	}
+	sshkey_free(lineinfo.key);
+	free(lineinfo.line);
+	free(line);
+	return r;
+}
+
+int
+hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx,
+    const char *host, const char *ip, u_int options, u_int note)
+{
+	FILE *f;
+	int r, oerrno;
+
+	if ((f = fopen(path, "r")) == NULL)
+		return SSH_ERR_SYSTEM_ERROR;
+
+	debug3_f("reading file \"%s\"", path);
+	r = hostkeys_foreach_file(path, f, callback, ctx, host, ip,
+	    options, note);
+	oerrno = errno;
+	fclose(f);
+	errno = oerrno;
+	return r;
+}