1 /*
2  * FreeRTOS memory safety proofs with CBMC.
3  * Copyright (C) 2022 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
4  *
5  * Permission is hereby granted, free of charge, to any person
6  * obtaining a copy of this software and associated documentation
7  * files (the "Software"), to deal in the Software without
8  * restriction, including without limitation the rights to use, copy,
9  * modify, merge, publish, distribute, sublicense, and/or sell copies
10  * of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be
14  * included in all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
20  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
21  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23  * SOFTWARE.
24  *
25  * http://aws.amazon.com/freertos
26  * http://www.FreeRTOS.org
27  */
28 
29 /* FreeRTOS includes. */
30 #include "FreeRTOS.h"
31 #include "queue.h"
32 
33 /* FreeRTOS+TCP includes. */
34 #include "FreeRTOS_IP.h"
35 #include "FreeRTOS_IP_Private.h"
36 #include "FreeRTOS_TCP_IP.h"
37 #include "FreeRTOS_ND.h"
38 
39 /* CBMC includes. */
40 #include "../../utility/memory_assignments.c"
41 #include "cbmc.h"
42 
43 extern NDCacheRow_t xNDCache[ ipconfigND_CACHE_ENTRIES ];
44 
45 /* The checksum generation is stubbed out since the actual checksum
46  * does not matter. The stub will return an indeterminate value each time. */
usGenerateProtocolChecksum(const uint8_t * const pucEthernetBuffer,size_t uxBufferLength,BaseType_t xOutgoingPacket)47 uint16_t usGenerateProtocolChecksum( const uint8_t * const pucEthernetBuffer,
48                                      size_t uxBufferLength,
49                                      BaseType_t xOutgoingPacket )
50 {
51     uint16_t usReturn;
52 
53     __CPROVER_assert( pucEthernetBuffer != NULL, "The ethernet buffer cannot be NULL" );
54     __CPROVER_assert( __CPROVER_r_ok( pucEthernetBuffer, uxBufferLength ), "pucEthernetBuffer should be readable." );
55 
56     /* Return an indeterminate value. */
57     return usReturn;
58 }
59 
60 /* This function has been tested separately. Therefore, we assume that the implementation is correct. */
vReturnEthernetFrame(NetworkBufferDescriptor_t * pxNetworkBuffer,BaseType_t xReleaseAfterSend)61 void vReturnEthernetFrame( NetworkBufferDescriptor_t * pxNetworkBuffer,
62                            BaseType_t xReleaseAfterSend )
63 {
64     __CPROVER_assert( pxNetworkBuffer != NULL, "The network buffer descriptor cannot be NULL." );
65 }
66 
67 /* This function has been tested separately. Therefore, we assume that the implementation is correct. */
vReceiveNA(const NetworkBufferDescriptor_t * pxNetworkBuffer)68 void vReceiveNA( const NetworkBufferDescriptor_t * pxNetworkBuffer )
69 {
70     __CPROVER_assert( pxNetworkBuffer != NULL, "The network buffer descriptor cannot be NULL." );
71 }
72 
73 /* This function has been tested separately. Therefore, we assume that the implementation is correct. */
xSendEventStructToIPTask(const IPStackEvent_t * pxEvent,TickType_t uxTimeout)74 BaseType_t xSendEventStructToIPTask( const IPStackEvent_t * pxEvent,
75                                      TickType_t uxTimeout )
76 {
77     BaseType_t xReturn;
78 
79     __CPROVER_assume( xReturn == pdPASS || xReturn == pdFAIL );
80 
81     return xReturn;
82 }
83 
84 /* This is an output function implemented by a third party and
85  * need not be tested with this proof. */
NetworkInterfaceOutputFunction_Stub(struct xNetworkInterface * pxDescriptor,NetworkBufferDescriptor_t * const pxNetworkBuffer,BaseType_t xReleaseAfterSend)86 BaseType_t NetworkInterfaceOutputFunction_Stub( struct xNetworkInterface * pxDescriptor,
87                                                 NetworkBufferDescriptor_t * const pxNetworkBuffer,
88                                                 BaseType_t xReleaseAfterSend )
89 {
90     __CPROVER_assert( pxDescriptor != NULL, "The network interface cannot be NULL." );
91     __CPROVER_assert( pxNetworkBuffer != NULL, "The network buffer descriptor cannot be NULL." );
92     __CPROVER_assert( pxNetworkBuffer->pucEthernetBuffer != NULL, "The Ethernet buffer cannot be NULL." );
93     return 0;
94 }
95 
96 /* Abstraction of this functions creates and return an endpoint, real endpoint doesn't matter in this test. */
FreeRTOS_FindEndPointOnIP_IPv6(const IPv6_Address_t * pxIPAddress)97 NetworkEndPoint_t * FreeRTOS_FindEndPointOnIP_IPv6( const IPv6_Address_t * pxIPAddress )
98 {
99     NetworkEndPoint_t * pxEndPoints = NULL;
100 
101     __CPROVER_assert( pxIPAddress != NULL, "The pxIPAddress cannot be NULL." );
102 
103     pxEndPoints = ( NetworkEndPoint_t * ) safeMalloc( sizeof( NetworkEndPoint_t ) );
104 
105     if( ensure_memory_is_valid( pxEndPoints, sizeof( NetworkEndPoint_t ) ) )
106     {
107         /* Interface init. */
108         pxEndPoints->pxNetworkInterface = ( NetworkInterface_t * ) safeMalloc( sizeof( NetworkInterface_t ) );
109         __CPROVER_assume( pxEndPoints->pxNetworkInterface != NULL );
110 
111         pxEndPoints->pxNext = NULL;
112         pxEndPoints->pxNetworkInterface->pfOutput = NetworkInterfaceOutputFunction_Stub;
113     }
114 
115     return pxEndPoints;
116 }
117 
harness()118 void harness()
119 {
120     NetworkBufferDescriptor_t * pxNetworkBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
121     uint32_t ulLen;
122     uint16_t usEthernetBufferSize;
123     NetworkBufferDescriptor_t xLocalBuffer;
124 
125     /* The code does not expect pxNetworkBuffer to be NULL. */
126     __CPROVER_assume( pxNetworkBuffer != NULL );
127 
128     __CPROVER_assume( ( ulLen >= sizeof( ICMPPacket_IPv6_t ) ) && ( ulLen < ipconfigNETWORK_MTU ) );
129 
130     pxNetworkBuffer->xDataLength = ulLen;
131     pxNetworkBuffer->pucEthernetBuffer = safeMalloc( ulLen );
132     __CPROVER_assume( pxNetworkBuffer->pucEthernetBuffer != NULL );
133 
134     /* Add an end point to the network buffer present. Its assumed that the
135      * network interface layer correctly assigns the end point to the generated buffer. */
136     pxNetworkBuffer->pxEndPoint = ( NetworkEndPoint_t * ) safeMalloc( sizeof( NetworkEndPoint_t ) );
137 
138     /* This assumption is made because the function is validating IPv6 related functionality
139      * which is validated only when bIPv6 is set*/
140     __CPROVER_assume( ( pxNetworkBuffer->pxEndPoint != NULL ) && ( pxNetworkBuffer->pxEndPoint->bits.bIPv6 == pdTRUE_UNSIGNED ) );
141 
142     /* Non deterministically determine whether the pxARPWaitingNetworkBuffer will
143      * point to some valid data or will it be NULL. */
144     if( nondet_bool() )
145     {
146         /* The packet must at least be as big as an IPv6 Packet. The size is not
147          * checked in the function as the pointer is stored by the IP-task itself
148          * and therefore it will always be of the required size. */
149         __CPROVER_assume( usEthernetBufferSize >= sizeof( IPPacket_IPv6_t ) );
150 
151         /* Add matching data length to the network buffer descriptor. */
152         __CPROVER_assume( xLocalBuffer.xDataLength == usEthernetBufferSize );
153 
154         xLocalBuffer.pucEthernetBuffer = safeMalloc( usEthernetBufferSize );
155 
156         /* Since this pointer is maintained by the IP-task, either the pointer
157          * pxARPWaitingNetworkBuffer will be NULL or xLocalBuffer.pucEthernetBuffer
158          * will be non-NULL. */
159         __CPROVER_assume( xLocalBuffer.pucEthernetBuffer != NULL );
160 
161         pxARPWaitingNetworkBuffer = &xLocalBuffer;
162     }
163     else
164     {
165         pxARPWaitingNetworkBuffer = NULL;
166     }
167 
168     prvProcessICMPMessage_IPv6( pxNetworkBuffer );
169 }
170