- markus@cvs.openbsd.org 2013/03/07 19:27:25

     [auth.h auth2-chall.c auth2.c monitor.c sshd_config.5]
     add submethod support to AuthenticationMethods; ok and freedback djm@

6 files changed, 91 insertions, 34 deletions

diff --git a/ChangeLog b/ChangeLog
index 38f6fa8c3..7be6f7bfe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -19,6 +19,9 @@
      have included a style (e.g. "root:skey") when checking public key
      signatures. Fixes public key and hostbased auth when the client specified
      a style; ok markus@
+   - markus@cvs.openbsd.org 2013/03/07 19:27:25
+     [auth.h auth2-chall.c auth2.c monitor.c sshd_config.5]
+     add submethod support to AuthenticationMethods; ok and freedback djm@
 
 20130418
  - (djm) [config.guess config.sub] Update to last versions before they switch
diff --git a/auth.h b/auth.h
index c6fe84722..7ff59f1ba 100644
--- a/auth.h
+++ b/auth.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.h,v 1.72 2012/12/02 20:34:09 djm Exp $ */
+/* $OpenBSD: auth.h,v 1.73 2013/03/07 19:27:25 markus Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -157,8 +157,9 @@ void	userauth_send_banner(const char *);
 
 char    *auth2_read_banner(void);
 int      auth2_methods_valid(const char *, int);
-int      auth2_update_methods_lists(Authctxt *, const char *);
+int      auth2_update_methods_lists(Authctxt *, const char *, const char *);
 int      auth2_setup_methods_lists(Authctxt *);
+int      auth2_method_allowed(Authctxt *, const char *, const char *);
 
 void    privsep_challenge_enable(void);
 
diff --git a/auth2-chall.c b/auth2-chall.c
index 6505d4009..ed1acdd3b 100644
--- a/auth2-chall.c
+++ b/auth2-chall.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-chall.c,v 1.36 2012/12/03 00:14:06 djm Exp $ */
+/* $OpenBSD: auth2-chall.c,v 1.37 2013/03/07 19:27:25 markus Exp $ */
 /*
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
  * Copyright (c) 2001 Per Allansson.  All rights reserved.
@@ -155,7 +155,7 @@ kbdint_free(KbdintAuthctxt *kbdintctxt)
 }
 /* get next device */
 static int
-kbdint_next_device(KbdintAuthctxt *kbdintctxt)
+kbdint_next_device(Authctxt *authctxt, KbdintAuthctxt *kbdintctxt)
 {
         size_t len;
         char *t;
@@ -169,9 +169,13 @@ kbdint_next_device(KbdintAuthctxt *kbdintctxt)
 
                 if (len == 0)
                         break;
-                for (i = 0; devices[i]; i++)
+                for (i = 0; devices[i]; i++) {
+                        if (!auth2_method_allowed(authctxt,
+                            "keyboard-interactive", devices[i]->name))
+                                continue;
                         if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
                                 kbdintctxt->device = devices[i];
+                }
                 t = kbdintctxt->devices;
                 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
                 xfree(t);
@@ -221,7 +225,7 @@ auth2_challenge_start(Authctxt *authctxt)
         debug2("auth2_challenge_start: devices %s",
             kbdintctxt->devices ?  kbdintctxt->devices : "<empty>");
 
-        if (kbdint_next_device(kbdintctxt) == 0) {
+        if (kbdint_next_device(authctxt, kbdintctxt) == 0) {
                 auth2_challenge_stop(authctxt);
                 return 0;
         }
diff --git a/auth2.c b/auth2.c
index e367a1045..e44482164 100644
--- a/auth2.c
+++ b/auth2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2.c,v 1.126 2012/12/02 20:34:09 djm Exp $ */
+/* $OpenBSD: auth2.c,v 1.127 2013/03/07 19:27:25 markus Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -98,8 +98,12 @@ static void input_userauth_request(int, u_int32_t, void *);
 /* helper */
 static Authmethod *authmethod_lookup(Authctxt *, const char *);
 static char *authmethods_get(Authctxt *authctxt);
-static int method_allowed(Authctxt *, const char *);
-static int list_starts_with(const char *, const char *);
+
+#define MATCH_NONE      0       /* method or submethod mismatch */
+#define MATCH_METHOD    1       /* method matches (no submethod specified) */
+#define MATCH_BOTH      2       /* method and submethod match */
+#define MATCH_PARTIAL   3       /* method matches, submethod can't be checked */
+static int list_starts_with(const char *, const char *, const char *);
 
 char *
 auth2_read_banner(void)
@@ -316,7 +320,7 @@ userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
         }
 
         if (authenticated && options.num_auth_methods != 0) {
-                if (!auth2_update_methods_lists(authctxt, method)) {
+                if (!auth2_update_methods_lists(authctxt, method, submethod)) {
                         authenticated = 0;
                         partial = 1;
                 }
@@ -387,8 +391,9 @@ userauth_finish(Authctxt *authctxt, int authenticated, const char *method,
  * methods list. Returns 1 if allowed, or no methods lists configured.
  * 0 otherwise.
  */
-static int
-method_allowed(Authctxt *authctxt, const char *method)
+int
+auth2_method_allowed(Authctxt *authctxt, const char *method,
+    const char *submethod)
 {
         u_int i;
 
@@ -399,7 +404,8 @@ method_allowed(Authctxt *authctxt, const char *method)
         if (options.num_auth_methods == 0)
                 return 1;
         for (i = 0; i < authctxt->num_auth_methods; i++) {
-                if (list_starts_with(authctxt->auth_methods[i], method))
+                if (list_starts_with(authctxt->auth_methods[i], method,
+                    submethod) != MATCH_NONE)
                         return 1;
         }
         return 0;
@@ -419,7 +425,8 @@ authmethods_get(Authctxt *authctxt)
                 if (authmethods[i]->enabled == NULL ||
                     *(authmethods[i]->enabled) == 0)
                         continue;
-                if (!method_allowed(authctxt, authmethods[i]->name))
+                if (!auth2_method_allowed(authctxt, authmethods[i]->name,
+                    NULL))
                         continue;
                 if (buffer_len(&b) > 0)
                         buffer_append(&b, ",", 1);
@@ -442,7 +449,8 @@ authmethod_lookup(Authctxt *authctxt, const char *name)
                         if (authmethods[i]->enabled != NULL &&
                             *(authmethods[i]->enabled) != 0 &&
                             strcmp(name, authmethods[i]->name) == 0 &&
-                            method_allowed(authctxt, authmethods[i]->name))
+                            auth2_method_allowed(authctxt,
+                            authmethods[i]->name, NULL))
                                 return authmethods[i];
         debug2("Unrecognized authentication method name: %s",
             name ? name : "NULL");
@@ -457,7 +465,7 @@ authmethod_lookup(Authctxt *authctxt, const char *name)
 int
 auth2_methods_valid(const char *_methods, int need_enable)
 {
-        char *methods, *omethods, *method;
+        char *methods, *omethods, *method, *p;
         u_int i, found;
         int ret = -1;
 
@@ -468,6 +476,8 @@ auth2_methods_valid(const char *_methods, int need_enable)
         omethods = methods = xstrdup(_methods);
         while ((method = strsep(&methods, ",")) != NULL) {
                 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
+                        if ((p = strchr(method, ':')) != NULL)
+                                *p = '\0';
                         if (strcmp(method, authmethods[i]->name) != 0)
                                 continue;
                         if (need_enable) {
@@ -533,15 +543,30 @@ auth2_setup_methods_lists(Authctxt *authctxt)
 }
 
 static int
-list_starts_with(const char *methods, const char *method)
+list_starts_with(const char *methods, const char *method,
+    const char *submethod)
 {
         size_t l = strlen(method);
+        int match;
+        const char *p;
 
         if (strncmp(methods, method, l) != 0)
-                return 0;
-        if (methods[l] != ',' && methods[l] != '\0')
-                return 0;
-        return 1;
+                return MATCH_NONE;
+        p = methods + l;
+        match = MATCH_METHOD;
+        if (*p == ':') {
+                if (!submethod)
+                        return MATCH_PARTIAL;
+                l = strlen(submethod);
+                p += 1;
+                if (strncmp(submethod, p, l))
+                        return MATCH_NONE;
+                p += l;
+                match = MATCH_BOTH;
+        }
+        if (*p != ',' && *p != '\0')
+                return MATCH_NONE;
+        return match;
 }
 
 /*
@@ -550,14 +575,21 @@ list_starts_with(const char *methods, const char *method)
  * if it did.
  */
 static int
-remove_method(char **methods, const char *method)
+remove_method(char **methods, const char *method, const char *submethod)
 {
-        char *omethods = *methods;
+        char *omethods = *methods, *p;
         size_t l = strlen(method);
+        int match;
 
-        if (!list_starts_with(omethods, method))
+        match = list_starts_with(omethods, method, submethod);
+        if (match != MATCH_METHOD && match != MATCH_BOTH)
                 return 0;
-        *methods = xstrdup(omethods + l + (omethods[l] == ',' ? 1 : 0));
+        p = omethods + l;
+        if (submethod && match == MATCH_BOTH)
+                p += 1 + strlen(submethod); /* include colon */
+        if (*p == ',')
+                p++;
+        *methods = xstrdup(p);
         free(omethods);
         return 1;
 }
@@ -569,13 +601,15 @@ remove_method(char **methods, const char *method)
  * Returns 1 if the method completed any authentication list or 0 otherwise.
  */
 int
-auth2_update_methods_lists(Authctxt *authctxt, const char *method)
+auth2_update_methods_lists(Authctxt *authctxt, const char *method,
+    const char *submethod)
 {
         u_int i, found = 0;
 
         debug3("%s: updating methods list after \"%s\"", __func__, method);
         for (i = 0; i < authctxt->num_auth_methods; i++) {
-                if (!remove_method(&(authctxt->auth_methods[i]), method))
+                if (!remove_method(&(authctxt->auth_methods[i]), method,
+                    submethod))
                         continue;
                 found = 1;
                 if (*authctxt->auth_methods[i] == '\0') {
diff --git a/monitor.c b/monitor.c
index 34d7e1805..c0471a176 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.121 2013/03/07 00:19:59 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.122 2013/03/07 19:27:25 markus Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -392,7 +392,7 @@ monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor)
                                     "with SSH protocol 1");
                         if (authenticated &&
                             !auth2_update_methods_lists(authctxt,
-                            auth_method)) {
+                            auth_method, auth_submethod)) {
                                 debug3("%s: method %s: partial", __func__,
                                     auth_method);
                                 authenticated = 0;
@@ -949,9 +949,10 @@ mm_answer_bsdauthrespond(int sock, Buffer *m)
         debug3("%s: sending authenticated: %d", __func__, authok);
         mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
 
-        if (compat20)
-                auth_method = "keyboard-interactive"; /* XXX auth_submethod */
-        else
+        if (compat20) {
+                auth_method = "keyboard-interactive";
+                auth_submethod = "bsdauth";
+        } else
                 auth_method = "bsdauth";
 
         return (authok != 0);
diff --git a/sshd_config.5 b/sshd_config.5
index cfa480697..4fe3c55b6 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.156 2013/02/06 00:20:42 dtucker Exp $
-.Dd $Mdocdate: February 6 2013 $
+.\" $OpenBSD: sshd_config.5,v 1.157 2013/03/07 19:27:25 markus Exp $
+.Dd $Mdocdate: March 7 2013 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -180,6 +180,20 @@ Only methods that are next in one or more lists are offered at each stage,
 so for this example, it would not be possible to attempt password or
 keyboard-interactive authentication before public key.
 .Pp
+For keyboard interactive authentication it is also possible to
+restrict authentication to a specific device by appending a
+colon followed by the device identifier
+.Dq bsdauth ,
+.Dq pam ,
+or
+.Dq skey ,
+depending on the server configuration.
+For example,
+.Dq keyboard-interactive:bsdauth
+would restrict keyboard interactive authentication to the
+.Dq bsdauth
+device.
+.Pp
 This option is only available for SSH protocol 2 and will yield a fatal
 error if enabled if protocol 1 is also enabled.
 Note that each authentication method listed should also be explicitly enabled