From 2e3a1c6d693317dd70b46d40b9228c1175cb1fab Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Sun, 31 Mar 2019 22:23:03 +0100
Subject: [PATCH] Uppity: make a separate AuthPolicy per connection.

Despite the name, AuthPolicy in uxserver.c was also holding the state
of the current connection, including in particular how far through the
multi-step test keyboard-interactive interaction we are. But now that
Uppity can handle multiple connections in the same run, we need to
reset that state between connections. So the tree234s of acceptable
user keys now live in an AuthPolicyShared structure, and AuthPolicy
proper is a field of server_instance.
---
 unix/uxserver.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/unix/uxserver.c b/unix/uxserver.c
index 83e5f379..5706e029 100644
--- a/unix/uxserver.c
+++ b/unix/uxserver.c
@@ -112,8 +112,19 @@ char *platform_get_x_display(void) { return NULL; }
 
 static bool verbose;
 
+struct AuthPolicyShared {
+    struct AuthPolicy_ssh1_pubkey *ssh1keys;
+    struct AuthPolicy_ssh2_pubkey *ssh2keys;
+};
+
+struct AuthPolicy {
+    struct AuthPolicyShared *shared;
+    int kbdint_state;
+};
+
 struct server_instance {
     unsigned id;
+    AuthPolicy ap;
     LogPolicy logpolicy;
 };
 
@@ -163,11 +174,6 @@ struct AuthPolicy_ssh2_pubkey {
     struct AuthPolicy_ssh2_pubkey *next;
 };
 
-struct AuthPolicy {
-    struct AuthPolicy_ssh1_pubkey *ssh1keys;
-    struct AuthPolicy_ssh2_pubkey *ssh2keys;
-    int kbdint_state;
-};
 unsigned auth_methods(AuthPolicy *ap)
 {
     return (AUTHMETHOD_PUBLICKEY | AUTHMETHOD_PASSWORD | AUTHMETHOD_KBDINT |
@@ -211,7 +217,7 @@ int auth_password(AuthPolicy *ap, ptrlen username, ptrlen password,
 bool auth_publickey(AuthPolicy *ap, ptrlen username, ptrlen public_blob)
 {
     struct AuthPolicy_ssh2_pubkey *iter;
-    for (iter = ap->ssh2keys; iter; iter = iter->next) {
+    for (iter = ap->shared->ssh2keys; iter; iter = iter->next) {
         if (ptrlen_eq_ptrlen(public_blob, iter->public_blob))
             return true;
     }
@@ -221,7 +227,7 @@ RSAKey *auth_publickey_ssh1(
     AuthPolicy *ap, ptrlen username, mp_int *rsa_modulus)
 {
     struct AuthPolicy_ssh1_pubkey *iter;
-    for (iter = ap->ssh1keys; iter; iter = iter->next) {
+    for (iter = ap->shared->ssh1keys; iter; iter = iter->next) {
         if (mp_cmp_eq(rsa_modulus, iter->key.modulus))
             return &iter->key;
     }
@@ -416,7 +422,7 @@ struct server_config {
 
     RSAKey *hostkey1;
 
-    AuthPolicy *ap;
+    struct AuthPolicyShared *ap_shared;
 
     unsigned next_id;
 
@@ -429,7 +435,10 @@ static Plug *server_conn_plug(
 {
     struct server_instance *inst = snew(struct server_instance);
 
+    memset(inst, 0, sizeof(*inst));
+
     inst->id = cfg->next_id++;
+    inst->ap.shared = cfg->ap_shared;
     inst->logpolicy.vt = &server_logpolicy_vt;
 
     if (inst_out)
@@ -437,7 +446,7 @@ static Plug *server_conn_plug(
 
     return ssh_server_plug(
         cfg->conf, cfg->ssc, cfg->hostkeys, cfg->nhostkeys, cfg->hostkey1,
-        cfg->ap, &inst->logpolicy, &unix_live_sftpserver_vt);
+        &inst->ap, &inst->logpolicy, &unix_live_sftpserver_vt);
 }
 
 static void server_log(Plug *plug, int type, SockAddr *addr, int port,
@@ -517,14 +526,13 @@ int main(int argc, char **argv)
     size_t nhostkeys = 0, hostkeysize = 0;
     RSAKey *hostkey1 = NULL;
 
-    AuthPolicy ap;
+    struct AuthPolicyShared aps;
     SshServerConfig ssc;
 
     Conf *conf = make_ssh_server_conf();
 
-    ap.kbdint_state = 0;
-    ap.ssh1keys = NULL;
-    ap.ssh2keys = NULL;
+    aps.ssh1keys = NULL;
+    aps.ssh2keys = NULL;
 
     memset(&ssc, 0, sizeof(ssc));
 
@@ -667,8 +675,8 @@ int main(int argc, char **argv)
                 memcpy(blob, sb->u, sb->len);
                 node->public_blob = make_ptrlen(blob, sb->len);
 
-                node->next = ap.ssh2keys;
-                ap.ssh2keys = node;
+                node->next = aps.ssh2keys;
+                aps.ssh2keys = node;
 
                 strbuf_free(sb);
             } else if (keytype == SSH_KEYTYPE_SSH1_PUBLIC) {
@@ -687,8 +695,8 @@ int main(int argc, char **argv)
                 BinarySource_BARE_INIT(src, sb->u, sb->len);
                 get_rsa_ssh1_pub(src, &node->key, RSA_SSH1_EXPONENT_FIRST);
 
-                node->next = ap.ssh1keys;
-                ap.ssh1keys = node;
+                node->next = aps.ssh1keys;
+                aps.ssh1keys = node;
 
                 strbuf_free(sb);
             } else {
@@ -778,7 +786,7 @@ int main(int argc, char **argv)
     scfg.hostkeys = hostkeys;
     scfg.nhostkeys = nhostkeys;
     scfg.hostkey1 = hostkey1;
-    scfg.ap = &ap;
+    scfg.ap_shared = &aps;
     scfg.next_id = 0;
 
     if (listen_port >= 0) {