upstream: use OpenSSL's RSA reference counting hooks to

implicitly clean up pkcs11_key objects when their owning RSA object's
reference count drops to zero. Simplifies the cleanup path and makes it more
like ECDSA's

work by markus@, ok djm@

OpenBSD-Commit-ID: 74b9c98f405cd78f7148e9e4a4982336cd3df25c

1 files changed, 21 insertions, 35 deletions

diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
index d7b3a65f0..b8f2a3a4e 100644
--- a/ssh-pkcs11.c
+++ b/ssh-pkcs11.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-pkcs11.c,v 1.33 2019/01/20 23:08:24 djm Exp $ */
+/* $OpenBSD: ssh-pkcs11.c,v 1.34 2019/01/20 23:10:33 djm Exp $ */
 /*
  * Copyright (c) 2010 Markus Friedl.  All rights reserved.
  * Copyright (c) 2014 Pedro Martelletto. All rights reserved.
@@ -72,7 +72,6 @@ TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;
 struct pkcs11_key {
         struct pkcs11_provider  *provider;
         CK_ULONG                slotidx;
-        int                     (*orig_finish)(RSA *rsa);
         RSA_METHOD              *rsa_method;
         EC_KEY_METHOD           *ec_key_method;
         char                    *keyid;
@@ -190,23 +189,20 @@ pkcs11_del_provider(char *provider_id)
         return (-1);
 }
 
-/* openssl callback for freeing an RSA key */
-static int
-pkcs11_rsa_finish(RSA *rsa)
+/* release a wrapped object */
+static void
+pkcs11_k11_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
+    long argl, void *argp)
 {
-        struct pkcs11_key       *k11;
-        int rv = -1;
-
-        if ((k11 = RSA_get_app_data(rsa)) != NULL) {
-                if (k11->orig_finish)
-                        rv = k11->orig_finish(rsa);
-                if (k11->provider)
-                        pkcs11_provider_unref(k11->provider);
-                RSA_meth_free(k11->rsa_method);
-                free(k11->keyid);
-                free(k11);
-        }
-        return (rv);
+        struct pkcs11_key       *k11 = ptr;
+
+        debug("%s: parent %p ptr %p idx %d", __func__, parent, ptr, idx);
+        if (k11 == NULL)
+                return;
+        if (k11->provider)
+                pkcs11_provider_unref(k11->provider);
+        free(k11->keyid);
+        free(k11);
 }
 
 /* find a single 'obj' for given attributes */
@@ -366,6 +362,7 @@ pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
 }
 
 static RSA_METHOD *rsa_method;
+static int rsa_idx = 0;
 
 static int
 pkcs11_rsa_start_wrapper(void)
@@ -375,10 +372,13 @@ pkcs11_rsa_start_wrapper(void)
         rsa_method = RSA_meth_dup(RSA_get_default_method());
         if (rsa_method == NULL)
                 return (-1);
+        rsa_idx = RSA_get_ex_new_index(0, "ssh-pkcs11-rsa",
+            NULL, NULL, pkcs11_k11_free);
+        if (rsa_idx == -1)
+                return (-1);
         if (!RSA_meth_set1_name(rsa_method, "pkcs11") ||
             !RSA_meth_set_priv_enc(rsa_method, pkcs11_rsa_private_encrypt) ||
-            !RSA_meth_set_priv_dec(rsa_method, pkcs11_rsa_private_decrypt) ||
-            !RSA_meth_set_finish(rsa_method, pkcs11_rsa_finish)) {
+            !RSA_meth_set_priv_dec(rsa_method, pkcs11_rsa_private_decrypt)) {
                 error("%s: setup pkcs11 method failed", __func__);
                 return (-1);
         }
@@ -408,7 +408,7 @@ pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
 
         k11->rsa_method = rsa_method;
         RSA_set_method(rsa, k11->rsa_method);
-        RSA_set_ex_data(rsa, 0, k11);
+        RSA_set_ex_data(rsa, rsa_idx, k11);
         return (0);
 }
 
@@ -472,20 +472,6 @@ ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
 static EC_KEY_METHOD *ec_key_method;
 static int ec_key_idx = 0;
 
-static void
-pkcs11_k11_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
-    long argl, void *argp)
-{
-        struct pkcs11_key       *k11 = ptr;
-
-        if (k11 == NULL)
-                return;
-        if (k11->provider)
-                pkcs11_provider_unref(k11->provider);
-        free(k11->keyid);
-        free(k11);
-}
-
 static int
 pkcs11_ecdsa_start_wrapper(void)
 {