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authordjm@openbsd.org <djm@openbsd.org>2016-03-07 19:02:43 +0000
committerDamien Miller <djm@mindrot.org>2016-03-08 06:20:35 +1100
commit95767262caa6692eff1e1565be1f5cb297949a89 (patch)
tree1055360a328d0998dabb966f2e1002389f8c6c41 /auth.c
parentaf0bb38ffd1f2c4f9f43b0029be2efe922815255 (diff)
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
Diffstat (limited to 'auth.c')
-rw-r--r--auth.c145
1 files changed, 135 insertions, 10 deletions
diff --git a/auth.c b/auth.c
index 214c2c70..aae0593e 100644
--- a/auth.c
+++ b/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;
+ }
+}