upstream commit

refactor canohost.c: move functions that cache results closer
 to the places that use them (authn and session code). After this, no state is
 cached in canohost.c

feedback and ok markus@

Upstream-ID: 5f2e4df88d4803fc8ec59ec53629105e23ce625e

Author: djmdjm

auth-options.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.70 2015/12/10 17:08:40 mmcc Exp $ */
+/* $OpenBSD: auth-options.c,v 1.71 2016/03/07 19:02:43 djm Exp $ */
 /*
  * Author: Tatu Ylonen <[email protected]>
  * Copyright (c) 1995 Tatu Ylonen <[email protected]>, Espoo, Finland
@@ -29,6 +29,7 @@
 #include "ssherr.h"
 #include "log.h"
 #include "canohost.h"
+#include "packet.h"
 #include "sshbuf.h"
 #include "misc.h"
 #include "channels.h"
@@ -120,6 +121,7 @@ match_flag(const char *opt, int allow_negate, char **optsp, const char *msg)
 int
 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 {
+	struct ssh *ssh = active_state;		/* XXX */
 	const char *cp;
 	int i, r;
 
@@ -273,9 +275,9 @@ auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
 		}
 		cp = "from=\"";
 		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
-			const char *remote_ip = get_remote_ipaddr();
-			const char *remote_host = get_canonical_hostname(
-			    options.use_dns);
+			const char *remote_ip = ssh_remote_ipaddr(ssh);
+			const char *remote_host = auth_get_canonical_hostname(
+			    ssh, options.use_dns);
 			char *patterns = xmalloc(strlen(opts) + 1);
 
 			opts += strlen(cp);
@@ -457,6 +459,7 @@ parse_option_list(struct sshbuf *oblob, struct passwd *pw,
     char **cert_forced_command,
     int *cert_source_address_done)
 {
+	struct ssh *ssh = active_state;		/* XXX */
 	char *command, *allowed;
 	const char *remote_ip;
 	char *name = NULL;
@@ -530,7 +533,7 @@ parse_option_list(struct sshbuf *oblob, struct passwd *pw,
 					free(allowed);
 					goto out;
 				}
-				remote_ip = get_remote_ipaddr();
+				remote_ip = ssh_remote_ipaddr(ssh);
 				result = addr_match_cidr_list(remote_ip,
 				    allowed);
 				free(allowed);

auth-rh-rsa.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-rh-rsa.c,v 1.44 2014/07/15 15:54:14 millert Exp $ */
+/* $OpenBSD: auth-rh-rsa.c,v 1.45 2016/03/07 19:02:43 djm Exp $ */
 /*
  * Author: Tatu Ylonen <[email protected]>
  * Copyright (c) 1995 Tatu Ylonen <[email protected]>, Espoo, Finland
@@ -42,8 +42,8 @@
 extern ServerOptions options;
 
 int
-auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
-    Key *client_host_key)
+auth_rhosts_rsa_key_allowed(struct passwd *pw, const char *cuser,
+    const char *chost, Key *client_host_key)
 {
 	HostStatus host_status;
 
@@ -68,7 +68,8 @@ auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
 int
 auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
 {
-	char *chost;
+	struct ssh *ssh = active_state; /* XXX */
+	const char *chost;
 	struct passwd *pw = authctxt->pw;
 
 	debug("Trying rhosts with RSA host authentication for client user %.100s",
@@ -78,7 +79,7 @@ auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
 	    client_host_key->rsa == NULL)
 		return 0;
 
-	chost = (char *)get_canonical_hostname(options.use_dns);
+	chost = auth_get_canonical_hostname(ssh, options.use_dns);
 	debug("Rhosts RSA authentication: canonical host %.900s", chost);
 
 	if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {

auth-rhosts.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-rhosts.c,v 1.46 2014/12/23 22:42:48 djm Exp $ */
+/* $OpenBSD: auth-rhosts.c,v 1.47 2016/03/07 19:02:43 djm Exp $ */
 /*
  * Author: Tatu Ylonen <[email protected]>
  * Copyright (c) 1995 Tatu Ylonen <[email protected]>, Espoo, Finland
@@ -30,14 +30,15 @@
 #include <unistd.h>
 
 #include "packet.h"
-#include "buffer.h"
 #include "uidswap.h"
 #include "pathnames.h"
 #include "log.h"
 #include "misc.h"
+#include "buffer.h" /* XXX */
+#include "key.h" /* XXX */
 #include "servconf.h"
 #include "canohost.h"
-#include "key.h"
+#include "sshkey.h"
 #include "hostfile.h"
 #include "auth.h"
 
@@ -189,10 +190,11 @@ check_rhosts_file(const char *filename, const char *hostname,
 int
 auth_rhosts(struct passwd *pw, const char *client_user)
 {
+	struct ssh *ssh = active_state;	/* XXX */
 	const char *hostname, *ipaddr;
 
-	hostname = get_canonical_hostname(options.use_dns);
-	ipaddr = get_remote_ipaddr();
+	hostname = auth_get_canonical_hostname(ssh, options.use_dns);
+	ipaddr = ssh_remote_ipaddr(ssh);
 	return auth_rhosts2(pw, client_user, hostname, ipaddr);
 }
 

auth.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.113 2015/08/21 03:42:19 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.114 2016/03/07 19:02:43 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -27,6 +27,7 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/socket.h>
 
 #include <netinet/in.h>
 
@@ -50,6 +51,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <limits.h>
+#include <netdb.h>
 
 #include "xmalloc.h"
 #include "match.h"
@@ -97,6 +99,7 @@ int auth_debug_init;
 int
 allowed_user(struct passwd * pw)
 {
+	struct ssh *ssh = active_state; /* XXX */
 	struct stat st;
 	const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
 	u_int i;
@@ -182,8 +185,8 @@ allowed_user(struct passwd * pw)
 
 	if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
 	    options.num_deny_groups > 0 || options.num_allow_groups > 0) {
-		hostname = get_canonical_hostname(options.use_dns);
-		ipaddr = get_remote_ipaddr();
+		hostname = auth_get_canonical_hostname(ssh, options.use_dns);
+		ipaddr = ssh_remote_ipaddr(ssh);
 	}
 
 	/* Return false if user is listed in DenyUsers */
@@ -274,6 +277,7 @@ void
 auth_log(Authctxt *authctxt, int authenticated, int partial,
     const char *method, const char *submethod)
 {
+	struct ssh *ssh = active_state; /* XXX */
 	void (*authlog) (const char *fmt,...) = verbose;
 	char *authmsg;
 
@@ -300,8 +304,8 @@ auth_log(Authctxt *authctxt, int authenticated, int partial,
 	    submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
 	    authctxt->valid ? "" : "invalid user ",
 	    authctxt->user,
-	    get_remote_ipaddr(),
-	    get_remote_port(),
+	    ssh_remote_ipaddr(ssh),
+	    ssh_remote_port(ssh),
 	    compat20 ? "ssh2" : "ssh1",
 	    authctxt->info != NULL ? ": " : "",
 	    authctxt->info != NULL ? authctxt->info : "");
@@ -331,12 +335,14 @@ auth_log(Authctxt *authctxt, int authenticated, int partial,
 void
 auth_maxtries_exceeded(Authctxt *authctxt)
 {
+	struct ssh *ssh = active_state; /* XXX */
+
 	error("maximum authentication attempts exceeded for "
 	    "%s%.100s from %.200s port %d %s",
 	    authctxt->valid ? "" : "invalid user ",
 	    authctxt->user,
-	    get_remote_ipaddr(),
-	    get_remote_port(),
+	    ssh_remote_ipaddr(ssh),
+	    ssh_remote_port(ssh),
 	    compat20 ? "ssh2" : "ssh1");
 	packet_disconnect("Too many authentication failures");
 	/* NOTREACHED */
@@ -348,6 +354,8 @@ auth_maxtries_exceeded(Authctxt *authctxt)
 int
 auth_root_allowed(const char *method)
 {
+	struct ssh *ssh = active_state; /* XXX */
+
 	switch (options.permit_root_login) {
 	case PERMIT_YES:
 		return 1;
@@ -364,7 +372,8 @@ auth_root_allowed(const char *method)
 		}
 		break;
 	}
-	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
+	logit("ROOT LOGIN REFUSED FROM %.200s port %d",
+	    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
 	return 0;
 }
 
@@ -604,6 +613,7 @@ auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
 struct passwd *
 getpwnamallow(const char *user)
 {
+	struct ssh *ssh = active_state; /* XXX */
 #ifdef HAVE_LOGIN_CAP
 	extern login_cap_t *lc;
 #ifdef BSD_AUTH
@@ -639,8 +649,8 @@ getpwnamallow(const char *user)
 	}
 #endif
 	if (pw == NULL) {
-		logit("Invalid user %.100s from %.100s",
-		    user, get_remote_ipaddr());
+		logit("Invalid user %.100s from %.100s port %d",
+		    user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
 #ifdef CUSTOM_FAILED_LOGIN
 		record_failed_login(user,
 		    get_canonical_hostname(options.use_dns), "ssh");
@@ -773,3 +783,118 @@ fakepw(void)
 
 	return (&fake);
 }
+
+/*
+ * Returns the remote DNS hostname as a string. The returned string must not
+ * be freed. NB. this will usually trigger a DNS query the first time it is
+ * called.
+ * This function does additional checks on the hostname to mitigate some
+ * attacks on legacy rhosts-style authentication.
+ * XXX is RhostsRSAAuthentication vulnerable to these?
+ * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
+ */
+
+static char *
+remote_hostname(struct ssh *ssh)
+{
+	struct sockaddr_storage from;
+	socklen_t fromlen;
+	struct addrinfo hints, *ai, *aitop;
+	char name[NI_MAXHOST], ntop2[NI_MAXHOST];
+	const char *ntop = ssh_remote_ipaddr(ssh);
+
+	/* Get IP address of client. */
+	fromlen = sizeof(from);
+	memset(&from, 0, sizeof(from));
+	if (getpeername(ssh_packet_get_connection_in(ssh),
+	    (struct sockaddr *)&from, &fromlen) < 0) {
+		debug("getpeername failed: %.100s", strerror(errno));
+		return strdup(ntop);
+	}
+
+	ipv64_normalise_mapped(&from, &fromlen);
+	if (from.ss_family == AF_INET6)
+		fromlen = sizeof(struct sockaddr_in6);
+
+	debug3("Trying to reverse map address %.100s.", ntop);
+	/* Map the IP address to a host name. */
+	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
+	    NULL, 0, NI_NAMEREQD) != 0) {
+		/* Host name not found.  Use ip address. */
+		return strdup(ntop);
+	}
+
+	/*
+	 * if reverse lookup result looks like a numeric hostname,
+	 * someone is trying to trick us by PTR record like following:
+	 *	1.1.1.10.in-addr.arpa.	IN PTR	2.3.4.5
+	 */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
+	hints.ai_flags = AI_NUMERICHOST;
+	if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
+		logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
+		    name, ntop);
+		freeaddrinfo(ai);
+		return strdup(ntop);
+	}
+
+	/* Names are stored in lowercase. */
+	lowercase(name);
+
+	/*
+	 * Map it back to an IP address and check that the given
+	 * address actually is an address of this host.  This is
+	 * necessary because anyone with access to a name server can
+	 * define arbitrary names for an IP address. Mapping from
+	 * name to IP address can be trusted better (but can still be
+	 * fooled if the intruder has access to the name server of
+	 * the domain).
+	 */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = from.ss_family;
+	hints.ai_socktype = SOCK_STREAM;
+	if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
+		logit("reverse mapping checking getaddrinfo for %.700s "
+		    "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
+		return strdup(ntop);
+	}
+	/* Look for the address from the list of addresses. */
+	for (ai = aitop; ai; ai = ai->ai_next) {
+		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
+		    sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
+		    (strcmp(ntop, ntop2) == 0))
+				break;
+	}
+	freeaddrinfo(aitop);
+	/* If we reached the end of the list, the address was not there. */
+	if (ai == NULL) {
+		/* Address not found for the host name. */
+		logit("Address %.100s maps to %.600s, but this does not "
+		    "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
+		    ntop, name);
+		return strdup(ntop);
+	}
+	return strdup(name);
+}
+
+/*
+ * Return the canonical name of the host in the other side of the current
+ * connection.  The host name is cached, so it is efficient to call this
+ * several times.
+ */
+
+const char *
+auth_get_canonical_hostname(struct ssh *ssh, int use_dns)
+{
+	static char *dnsname;
+
+	if (!use_dns)
+		return ssh_remote_ipaddr(ssh);
+	else if (dnsname != NULL)
+		return dnsname;
+	else {
+		dnsname = remote_hostname(ssh);
+		return dnsname;
+	}
+}

auth.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.h,v 1.86 2015/12/04 16:41:28 markus Exp $ */
+/* $OpenBSD: auth.h,v 1.87 2016/03/07 19:02:43 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -197,6 +197,8 @@ FILE	*auth_openkeyfile(const char *, struct passwd *, int);
 FILE	*auth_openprincipals(const char *, struct passwd *, int);
 int	 auth_key_is_revoked(Key *);
 
+const char	*auth_get_canonical_hostname(struct ssh *, int);
+
 HostStatus
 check_key_in_hostfiles(struct passwd *, Key *, const char *,
     const char *, const char *);

auth2-hostbased.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-hostbased.c,v 1.25 2015/05/04 06:10:48 djm Exp $ */
+/* $OpenBSD: auth2-hostbased.c,v 1.26 2016/03/07 19:02:43 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -160,6 +160,7 @@ int
 hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
     Key *key)
 {
+	struct ssh *ssh = active_state; /* XXX */
 	const char *resolvedname, *ipaddr, *lookup, *reason;
 	HostStatus host_status;
 	int len;
@@ -168,8 +169,8 @@ hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
 	if (auth_key_is_revoked(key))
 		return 0;
 
-	resolvedname = get_canonical_hostname(options.use_dns);
-	ipaddr = get_remote_ipaddr();
+	resolvedname = auth_get_canonical_hostname(ssh, options.use_dns);
+	ipaddr = ssh_remote_ipaddr(ssh);
 
 	debug2("%s: chost %s resolvedname %s ipaddr %s", __func__,
 	    chost, resolvedname, ipaddr);