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ssh: Be more paranoid with host/domain names coming from the

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never write a name with bad characters to a known_hosts file.

replace recently-added valid_domain() check for hostnames going to
known_hosts with a more relaxed check for bad characters.

Obtained from:	OpenSSH-portable commit 445363433ba2
Obtained from:	OpenSSH-portable commit 3cae9f92a318
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Ed Maste 2023-02-06 11:45:52 -05:00
parent 2768d70567
commit 2e82822057
2 changed files with 19 additions and 4 deletions
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8
crypto/openssh/ssh.c
View file

@ -1,4 +1,4 @@
/* $OpenBSD: ssh.c,v 1.576 2022/09/17 10:33:18 djm Exp $ */
/* $OpenBSD: ssh.c,v 1.579 2022/10/24 22:43:36 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -251,6 +251,7 @@ static struct addrinfo *
resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
{
char strport[NI_MAXSERV];
const char *errstr = NULL;
struct addrinfo hints, *res;
int gaierr;
LogLevel loglevel = SYSLOG_LEVEL_DEBUG1;
@ -276,7 +277,10 @@ resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
return NULL;
}
if (cname != NULL && res->ai_canonname != NULL) {
if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
if (!valid_domain(res->ai_canonname, 0, &errstr)) {
error("ignoring bad CNAME \"%s\" for host \"%s\": %s",
res->ai_canonname, name, errstr);
} else if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
error_f("host \"%s\" cname \"%s\" too long (max %lu)",
name, res->ai_canonname, (u_long)clen);
if (clen > 0)

15
crypto/openssh/sshconnect.c
View file

@ -1,4 +1,4 @@
/* $OpenBSD: sshconnect.c,v 1.358 2022/08/26 08:16:27 djm Exp $ */
/* $OpenBSD: sshconnect.c,v 1.360 2022/11/03 21:59:20 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -935,7 +935,7 @@ check_host_key(char *hostname, const struct ssh_conn_info *cinfo,
char *ip = NULL, *host = NULL;
char hostline[1000], *hostp, *fp, *ra;
char msg[1024];
const char *type, *fail_reason;
const char *type, *fail_reason = NULL;
const struct hostkey_entry *host_found = NULL, *ip_found = NULL;
int len, cancelled_forwarding = 0, confirmed;
int local = sockaddr_is_local(hostaddr);
@ -960,6 +960,17 @@ check_host_key(char *hostname, const struct ssh_conn_info *cinfo,
return 0;
}
/*
* Don't ever try to write an invalid name to a known hosts file.
* Note: do this before get_hostfile_hostname_ipaddr() to catch
* '[' or ']' in the name before they are added.
*/
if (strcspn(hostname, "@?*#[]|'\'\"\\") != strlen(hostname)) {
debug_f("invalid hostname \"%s\"; will not record: %s",
hostname, fail_reason);
readonly = RDONLY;
}
/*
* Prepare the hostname and address strings used for hostkey lookup.
* In some cases, these will have a port number appended.