Author: Paul Wolneykien <manowar@altlinux.org>
Date:   Wed Sep 6 11:47:40 2017 +0300

Refresh the slot list each time C_GetSlotList() is called

In order to make token insert and remove operations observable, it's
necessary to call C_GetSlotList() with NULL pointer argument. The
latter is a signal for each underlying PKCS#11 module to update the
slot and token status information.

The following is stated in the PKCS #11 Cryptographic Token Interface
Base Specification Version 2.40, 5.5 Slot and token management
functions:

"The set of slots accessible through a Cryptoki library is checked at
the time that C_GetSlotList, for list length prediction (NULL
pSlotList argument) is called. If an application calls C_GetSlotList
with a non-NULL pSlotList, and *then* the user adds or removes a
hardware device, the changed slot list will only be visible and
effective if C_GetSlotList is called again with NULL."

(http://docs.oasis-open.org/pkcs11/pkcs11-base/v2.40/os/pkcs11-base-v2.40-os.html)

diff --git a/p11-kit/proxy.c b/p11-kit/proxy.c
index 8c437a0..6adc822 100644
--- a/p11-kit/proxy.c
+++ b/p11-kit/proxy.c
@@ -248,13 +248,58 @@ modules_dup (CK_FUNCTION_LIST **modules)
 }
 
 static CK_RV
-proxy_create (Proxy **res)
+proxy_refresh_slots (Proxy *py)
 {
-	CK_FUNCTION_LIST_PTR *f;
+    CK_FUNCTION_LIST_PTR *f;
 	CK_FUNCTION_LIST_PTR funcs;
 	CK_SLOT_ID_PTR slots;
 	CK_ULONG i, count;
-	CK_RV rv = CKR_OK;
+    CK_RV rv = CKR_OK;
+    
+    py->n_mappings = 0;
+    
+    for (f = py->inited; *f; ++f) {
+        funcs = *f;
+        assert (funcs != NULL);
+        slots = NULL;
+
+        /* Ask module for its slots */
+        rv = (funcs->C_GetSlotList) (FALSE, NULL, &count);
+        if (rv == CKR_OK && count) {
+            slots = calloc (sizeof (CK_SLOT_ID), count);
+            rv = (funcs->C_GetSlotList) (FALSE, slots, &count);
+        }
+
+        if (rv != CKR_OK) {
+            free (slots);
+            break;
+        }
+
+        return_val_if_fail (count == 0 || slots != NULL, CKR_GENERAL_ERROR);
+
+        if (count > 0) {
+            py->mappings = realloc (py->mappings, sizeof (Mapping) * (py->n_mappings + count));
+            return_val_if_fail (py->mappings != NULL, CKR_HOST_MEMORY);
+
+            /* And now add a mapping for each of those slots */
+            for (i = 0; i < count; ++i) {
+                py->mappings[py->n_mappings].funcs = funcs;
+                py->mappings[py->n_mappings].wrap_slot = py->n_mappings + MAPPING_OFFSET;
+                py->mappings[py->n_mappings].real_slot = slots[i];
+                ++py->n_mappings;
+            }
+        }
+        
+        free (slots);
+    }
+
+    return rv;
+}
+
+static CK_RV
+proxy_create (Proxy **res)
+{
+    CK_RV rv = CKR_OK;
 	Proxy *py;
 
 	py = calloc (1, sizeof (Proxy));
@@ -268,40 +313,7 @@ proxy_create (Proxy **res)
 	rv = p11_kit_modules_initialize (py->inited, NULL);
 
 	if (rv == CKR_OK) {
-		for (f = py->inited; *f; ++f) {
-			funcs = *f;
-			assert (funcs != NULL);
-			slots = NULL;
-
-			/* Ask module for its slots */
-			rv = (funcs->C_GetSlotList) (FALSE, NULL, &count);
-			if (rv == CKR_OK && count) {
-				slots = calloc (sizeof (CK_SLOT_ID), count);
-				rv = (funcs->C_GetSlotList) (FALSE, slots, &count);
-			}
-
-			if (rv != CKR_OK) {
-				free (slots);
-				break;
-			}
-
-			return_val_if_fail (count == 0 || slots != NULL, CKR_GENERAL_ERROR);
-
-			if (count > 0) {
-				py->mappings = realloc (py->mappings, sizeof (Mapping) * (py->n_mappings + count));
-				return_val_if_fail (py->mappings != NULL, CKR_HOST_MEMORY);
-
-				/* And now add a mapping for each of those slots */
-				for (i = 0; i < count; ++i) {
-					py->mappings[py->n_mappings].funcs = funcs;
-					py->mappings[py->n_mappings].wrap_slot = py->n_mappings + MAPPING_OFFSET;
-					py->mappings[py->n_mappings].real_slot = slots[i];
-					++py->n_mappings;
-				}
-			}
-
-			free (slots);
-		}
+        rv = proxy_refresh_slots (py);
 	}
 
 	if (rv != CKR_OK) {
@@ -428,6 +440,14 @@ proxy_C_GetSlotList (CK_X_FUNCTION_LIST *self,
 		} else {
 			index = 0;
 
+            /* Refresh the slots: some tokens might be inserted
+               or removed. */
+            rv = proxy_refresh_slots (state->px);
+            if ( CKR_OK != rv ) {
+                p11_unlock ();
+                return rv;
+            }
+            
 			/* Go through and build up a map */
 			for (i = 0; i < state->px->n_mappings; ++i) {
 				mapping = &state->px->mappings[i];