proxy: Reuse the existing slot ID mapping after fork

While the proxy module reassigns slot IDs in C_Initialize(), some
applications assume that valid slot IDs should never change across
multiple calls to C_Initialize().  This patch mitigates this by
preserving the slot IDs, if they are known to the proxy module.

p11-kit/Makefile.am

@@ -283,7 +283,8 @@ noinst_LTLIBRARIES += \
 	mock-two.la \
 	mock-three.la \
 	mock-four.la \
-	mock-five.la
+	mock-five.la \
+	mock-six.la
 
 mock_one_la_SOURCES = p11-kit/mock-module-ep.c
 mock_one_la_LIBADD = libp11-test.la libp11-common.la
@@ -307,6 +308,12 @@ mock_five_la_SOURCES = p11-kit/mock-module-ep3.c
 mock_five_la_LDFLAGS = $(mock_one_la_LDFLAGS)
 mock_five_la_LIBADD = $(mock_one_la_LIBADD)
 
+if !OS_WIN32
+mock_six_la_SOURCES = p11-kit/mock-module-ep4.c
+mock_six_la_LDFLAGS = $(mock_one_la_LDFLAGS)
+mock_six_la_LIBADD = $(mock_one_la_LIBADD) libp11-library.la
+endif
+
 EXTRA_DIST += \
 	p11-kit/fixtures \
 	p11-kit/test-mock.c \

p11-kit/fixtures/package-modules/six.module

@@ -0,0 +1,7 @@
+
+module: mock-six.so
+
+enable-in: test-proxy
+
+# the highest priority among others loaded by test-proxy
+priority: 100

p11-kit/mock-module-ep4.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2012 Stefan Walter
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * Redistributions in binary form must reproduce the
+ *       above copyright notice, this list of conditions and
+ *       the following disclaimer in the documentation and/or
+ *       other materials provided with the distribution.
+ *     * The names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Author: Stef Walter <stef@thewalter.net>
+ */
+
+#include "config.h"
+
+#define CRYPTOKI_EXPORTS 1
+#include "pkcs11.h"
+
+#include "mock.h"
+#include "test.h"
+
+#include <unistd.h>
+
+static pid_t init_pid;
+
+static CK_RV
+override_initialize (CK_VOID_PTR init_args)
+{
+	if (init_pid != getpid ())
+		return CKR_GENERAL_ERROR;
+	return mock_C_Initialize (init_args);
+}
+
+#ifdef OS_WIN32
+__declspec(dllexport)
+#endif
+CK_RV
+C_GetFunctionList (CK_FUNCTION_LIST_PTR_PTR list)
+{
+	mock_module_init ();
+	mock_module.C_GetFunctionList = C_GetFunctionList;
+	if (list == NULL)
+		return CKR_ARGUMENTS_BAD;
+	init_pid = getpid ();
+	mock_module.C_Initialize = override_initialize;
+	*list = &mock_module;
+	return CKR_OK;
+}

p11-kit/proxy.c

@@ -196,8 +196,8 @@ proxy_free (Proxy *py, unsigned finalize)
 		free (py->inited);
 		p11_dict_free (py->sessions);
 		free (py->mappings);
-		free (py);
 	}
+	free (py);
 }
 
 static CK_RV
@@ -248,12 +248,13 @@ modules_dup (CK_FUNCTION_LIST **modules)
 }
 
 static CK_RV
-proxy_create (Proxy **res)
+proxy_create (Proxy **res, Mapping *mappings, unsigned int n_mappings)
 {
 	CK_FUNCTION_LIST_PTR *f;
 	CK_FUNCTION_LIST_PTR funcs;
 	CK_SLOT_ID_PTR slots;
 	CK_ULONG i, count;
+	unsigned int j;
 	CK_RV rv = CKR_OK;
 	Proxy *py;
 
@@ -288,13 +289,18 @@ proxy_create (Proxy **res)
 			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) {
+					/* Reuse the existing mapping if any */
+					for (j = 0; j < n_mappings; ++j) {
+						if (mappings[j].funcs == funcs &&
+						    mappings[j].real_slot == slots[i])
+							break;
+					}
+					py->mappings = realloc (py->mappings, sizeof (Mapping) * (py->n_mappings + 1));
+					return_val_if_fail (py->mappings != NULL, CKR_HOST_MEMORY);
 					py->mappings[py->n_mappings].funcs = funcs;
-					py->mappings[py->n_mappings].wrap_slot = py->n_mappings + MAPPING_OFFSET;
+					py->mappings[py->n_mappings].wrap_slot = j == n_mappings ? py->n_mappings + MAPPING_OFFSET : mappings[j].wrap_slot;
 					py->mappings[py->n_mappings].real_slot = slots[i];
 					++py->n_mappings;
 				}
@@ -323,6 +329,8 @@ proxy_C_Initialize (CK_X_FUNCTION_LIST *self,
 {
 	State *state = (State *)self;
 	bool initialize = false;
+	Mapping *mappings = NULL;
+	unsigned int n_mappings = 0;
 	Proxy *py;
 	CK_RV rv;
 
@@ -338,8 +346,15 @@ proxy_C_Initialize (CK_X_FUNCTION_LIST *self,
 			unsigned call_finalize = 1;
 
 			initialize = true;
-			if (PROXY_FORKED(state->px))
+			if (PROXY_FORKED(state->px)) {
 				call_finalize = 0;
+				if (state->px->mappings) {
+					mappings = state->px->mappings;
+					n_mappings = state->px->n_mappings;
+					state->px->mappings = NULL;
+					state->px->n_mappings = 0;
+				}
+			}
 			proxy_free (state->px, call_finalize);
 
 			state->px = NULL;
@@ -354,7 +369,8 @@ proxy_C_Initialize (CK_X_FUNCTION_LIST *self,
 		return CKR_OK;
 	}
 
-	rv = proxy_create (&py);
+	rv = proxy_create (&py, mappings, n_mappings);
+	free (mappings);
 	if (rv != CKR_OK) {
 		p11_debug ("out: %lu", rv);
 		return rv;

p11-kit/test-proxy.c

@@ -121,6 +121,8 @@ test_initialize_child (void)
 	CK_RV rv;
 	pid_t pid;
 	int st;
+	CK_SLOT_ID slots[32], last_slot;
+	CK_ULONG count, last_count;
 
 	rv = C_GetFunctionList (&proxy);
 	assert (rv == CKR_OK);
@@ -130,6 +132,11 @@ test_initialize_child (void)
 	rv = proxy->C_Initialize(NULL);
 	assert_num_eq (rv, CKR_OK);
 
+	rv = proxy->C_GetSlotList (CK_FALSE, slots, &count);
+	assert_num_cmp (count, >=, 2);
+	last_slot = slots[count - 1];
+	last_count = count;
+
 	pid = fork ();
 	if (!pid) {
 		/* The PKCS#11 Usage Guide (v2.40) advocates in §2.5.2 that
@@ -149,6 +156,17 @@ test_initialize_child (void)
 		rv = proxy->C_Initialize(NULL);
 		assert_num_eq (rv, CKR_OK);
 
+		rv = proxy->C_GetSlotList (CK_FALSE, slots, &count);
+		assert_num_eq (rv, CKR_OK);
+		assert_num_cmp (count, >=, 2);
+
+		/* One of the module initializations should fail after
+		 * fork (see mock-module-ep4.c) and the total number
+		 * of slots should be less than last_count. */
+		assert_num_cmp (count, <, last_count);
+		/* Check if the last valid slot ID is preserved */
+		assert_num_eq (slots[count - 1], last_slot);
+
 		rv = proxy->C_Finalize (NULL);
 		assert_num_eq (rv, CKR_OK);