559 lines
19 KiB
C
559 lines
19 KiB
C
/*
|
|
* Message Processing Stack, Reader implementation
|
|
*
|
|
* Copyright The Mbed TLS Contributors
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
* not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*
|
|
* This file is part of Mbed TLS (https://tls.mbed.org)
|
|
*/
|
|
|
|
#include "mps_reader.h"
|
|
#include "mps_common.h"
|
|
#include "mps_trace.h"
|
|
|
|
#include <string.h>
|
|
|
|
#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
|
|
!defined(inline) && !defined(__cplusplus)
|
|
#define inline __inline
|
|
#endif
|
|
|
|
#if defined(MBEDTLS_MPS_ENABLE_TRACE)
|
|
static int mbedtls_mps_trace_id = MBEDTLS_MPS_TRACE_BIT_READER;
|
|
#endif /* MBEDTLS_MPS_ENABLE_TRACE */
|
|
|
|
/*
|
|
* GENERAL NOTE ON CODING STYLE
|
|
*
|
|
* The following code intentionally separates memory loads
|
|
* and stores from other operations (arithmetic or branches).
|
|
* This leads to the introduction of many local variables
|
|
* and significantly increases the C-code line count, but
|
|
* should not increase the size of generated assembly.
|
|
*
|
|
* The reason for this is twofold:
|
|
* (1) It will ease verification efforts using the VST
|
|
* (Verified Software Toolchain)
|
|
* whose program logic cannot directly reason
|
|
* about instructions containing a load or store in
|
|
* addition to other operations (e.g. *p = *q or
|
|
* tmp = *p + 42).
|
|
* (2) Operating on local variables and writing the results
|
|
* back to the target contexts on success only
|
|
* allows to maintain structure invariants even
|
|
* on failure - this in turn has two benefits:
|
|
* (2.a) If for some reason an error code is not caught
|
|
* and operation continues, functions are nonetheless
|
|
* called with sane contexts, reducing the risk
|
|
* of dangerous behavior.
|
|
* (2.b) Randomized testing is easier if structures
|
|
* remain intact even in the face of failing
|
|
* and/or non-sensical calls.
|
|
* Moreover, it might even reduce code-size because
|
|
* the compiler need not write back temporary results
|
|
* to memory in case of failure.
|
|
*
|
|
*/
|
|
|
|
static inline int mps_reader_is_accumulating(
|
|
mbedtls_mps_reader const *rd )
|
|
{
|
|
mbedtls_mps_size_t acc_remaining;
|
|
if( rd->acc == NULL )
|
|
return( 0 );
|
|
|
|
acc_remaining = rd->acc_share.acc_remaining;
|
|
return( acc_remaining > 0 );
|
|
}
|
|
|
|
static inline int mps_reader_is_producing(
|
|
mbedtls_mps_reader const *rd )
|
|
{
|
|
unsigned char *frag = rd->frag;
|
|
return( frag == NULL );
|
|
}
|
|
|
|
static inline int mps_reader_is_consuming(
|
|
mbedtls_mps_reader const *rd )
|
|
{
|
|
return( !mps_reader_is_producing( rd ) );
|
|
}
|
|
|
|
static inline mbedtls_mps_size_t mps_reader_get_fragment_offset(
|
|
mbedtls_mps_reader const *rd )
|
|
{
|
|
unsigned char *acc = rd->acc;
|
|
mbedtls_mps_size_t frag_offset;
|
|
|
|
if( acc == NULL )
|
|
return( 0 );
|
|
|
|
frag_offset = rd->acc_share.frag_offset;
|
|
return( frag_offset );
|
|
}
|
|
|
|
static inline mbedtls_mps_size_t mps_reader_serving_from_accumulator(
|
|
mbedtls_mps_reader const *rd )
|
|
{
|
|
mbedtls_mps_size_t frag_offset, end;
|
|
|
|
frag_offset = mps_reader_get_fragment_offset( rd );
|
|
end = rd->end;
|
|
|
|
return( end < frag_offset );
|
|
}
|
|
|
|
static inline void mps_reader_zero( mbedtls_mps_reader *rd )
|
|
{
|
|
/* A plain memset() would likely be more efficient,
|
|
* but the current way of zeroing makes it harder
|
|
* to overlook fields which should not be zero-initialized.
|
|
* It's also more suitable for FV efforts since it
|
|
* doesn't require reasoning about structs being
|
|
* interpreted as unstructured binary blobs. */
|
|
static mbedtls_mps_reader const zero =
|
|
{ .frag = NULL,
|
|
.frag_len = 0,
|
|
.commit = 0,
|
|
.end = 0,
|
|
.pending = 0,
|
|
.acc = NULL,
|
|
.acc_len = 0,
|
|
.acc_available = 0,
|
|
.acc_share = { .acc_remaining = 0 }
|
|
};
|
|
*rd = zero;
|
|
}
|
|
|
|
int mbedtls_mps_reader_init( mbedtls_mps_reader *rd,
|
|
unsigned char *acc,
|
|
mbedtls_mps_size_t acc_len )
|
|
{
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_init" );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"* Accumulator size: %u bytes", (unsigned) acc_len );
|
|
mps_reader_zero( rd );
|
|
rd->acc = acc;
|
|
rd->acc_len = acc_len;
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
int mbedtls_mps_reader_free( mbedtls_mps_reader *rd )
|
|
{
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_free" );
|
|
mps_reader_zero( rd );
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
int mbedtls_mps_reader_feed( mbedtls_mps_reader *rd,
|
|
unsigned char *new_frag,
|
|
mbedtls_mps_size_t new_frag_len )
|
|
{
|
|
mbedtls_mps_size_t copy_to_acc;
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_feed" );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"* Fragment length: %u bytes", (unsigned) new_frag_len );
|
|
|
|
if( new_frag == NULL )
|
|
MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_READER_INVALID_ARG );
|
|
|
|
MBEDTLS_MPS_STATE_VALIDATE_RAW( mps_reader_is_producing( rd ),
|
|
"mbedtls_mps_reader_feed() requires reader to be in producing mode" );
|
|
|
|
if( mps_reader_is_accumulating( rd ) )
|
|
{
|
|
unsigned char *acc = rd->acc;
|
|
mbedtls_mps_size_t ar = rd->acc_share.acc_remaining;
|
|
mbedtls_mps_size_t aa = rd->acc_available;
|
|
|
|
/* Skip over parts of the accumulator that have already been filled. */
|
|
acc += aa;
|
|
|
|
copy_to_acc = ar;
|
|
if( copy_to_acc > new_frag_len )
|
|
copy_to_acc = new_frag_len;
|
|
|
|
/* Copy new contents to accumulator. */
|
|
if( copy_to_acc > 0 )
|
|
memcpy( acc, new_frag, copy_to_acc );
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Copy new data of size %u of %u into accumulator at offset %u",
|
|
(unsigned) copy_to_acc, (unsigned) new_frag_len, (unsigned) aa );
|
|
|
|
/* Check if, with the new fragment, we have enough data. */
|
|
ar -= copy_to_acc;
|
|
if( ar > 0 )
|
|
{
|
|
/* We need to accumulate more data. Stay in producing mode. */
|
|
aa += copy_to_acc;
|
|
rd->acc_share.acc_remaining = ar;
|
|
rd->acc_available = aa;
|
|
MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_READER_NEED_MORE );
|
|
}
|
|
|
|
/* We have filled the accumulator: Move to consuming mode. */
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Enough data available to serve user request" );
|
|
|
|
/* Remember overlap of accumulator and fragment. */
|
|
rd->acc_share.frag_offset = aa;
|
|
aa += copy_to_acc;
|
|
rd->acc_available = aa;
|
|
}
|
|
else /* Not accumulating */
|
|
{
|
|
rd->acc_share.frag_offset = 0;
|
|
}
|
|
|
|
rd->frag = new_frag;
|
|
rd->frag_len = new_frag_len;
|
|
rd->commit = 0;
|
|
rd->end = 0;
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
|
|
int mbedtls_mps_reader_get( mbedtls_mps_reader *rd,
|
|
mbedtls_mps_size_t desired,
|
|
unsigned char **buffer,
|
|
mbedtls_mps_size_t *buflen )
|
|
{
|
|
unsigned char *frag;
|
|
mbedtls_mps_size_t frag_len, frag_offset, end, frag_fetched, frag_remaining;
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_get" );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"* Bytes requested: %u", (unsigned) desired );
|
|
|
|
MBEDTLS_MPS_STATE_VALIDATE_RAW( mps_reader_is_consuming( rd ),
|
|
"mbedtls_mps_reader_get() requires reader to be in consuming mode" );
|
|
|
|
end = rd->end;
|
|
frag_offset = mps_reader_get_fragment_offset( rd );
|
|
|
|
/* Check if we're still serving from the accumulator. */
|
|
if( mps_reader_serving_from_accumulator( rd ) )
|
|
{
|
|
/* Illustration of supported and unsupported cases:
|
|
*
|
|
* - Allowed #1
|
|
*
|
|
* +-----------------------------------+
|
|
* | frag |
|
|
* +-----------------------------------+
|
|
*
|
|
* end end+desired
|
|
* | |
|
|
* +-----v-------v-------------+
|
|
* | acc |
|
|
* +---------------------------+
|
|
* | |
|
|
* fo/frag_offset aa/acc_available
|
|
*
|
|
* - Allowed #2
|
|
*
|
|
* +-----------------------------------+
|
|
* | frag |
|
|
* +-----------------------------------+
|
|
*
|
|
* end end+desired
|
|
* | |
|
|
* +----------v----------------v
|
|
* | acc |
|
|
* +---------------------------+
|
|
* | |
|
|
* fo/frag_offset aa/acc_available
|
|
*
|
|
* - Not allowed #1 (could be served, but we don't actually use it):
|
|
*
|
|
* +-----------------------------------+
|
|
* | frag |
|
|
* +-----------------------------------+
|
|
*
|
|
* end end+desired
|
|
* | |
|
|
* +------v-------------v------+
|
|
* | acc |
|
|
* +---------------------------+
|
|
* | |
|
|
* fo/frag_offset aa/acc_available
|
|
*
|
|
*
|
|
* - Not allowed #2 (can't be served with a contiguous buffer):
|
|
*
|
|
* +-----------------------------------+
|
|
* | frag |
|
|
* +-----------------------------------+
|
|
*
|
|
* end end + desired
|
|
* | |
|
|
* +------v--------------------+ v
|
|
* | acc |
|
|
* +---------------------------+
|
|
* | |
|
|
* fo/frag_offset aa/acc_available
|
|
*
|
|
* In case of Allowed #2 we're switching to serve from
|
|
* `frag` starting from the next call to mbedtls_mps_reader_get().
|
|
*/
|
|
|
|
unsigned char *acc;
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Serve the request from the accumulator" );
|
|
if( frag_offset - end < desired )
|
|
{
|
|
mbedtls_mps_size_t acc_available;
|
|
acc_available = rd->acc_available;
|
|
if( acc_available - end != desired )
|
|
{
|
|
/* It might be possible to serve some of these situations by
|
|
* making additional space in the accumulator, removing those
|
|
* parts that have already been committed.
|
|
* On the other hand, this brings additional complexity and
|
|
* enlarges the code size, while there doesn't seem to be a use
|
|
* case where we don't attempt exactly the same `get` calls when
|
|
* resuming on a reader than what we tried before pausing it.
|
|
* If we believe we adhere to this restricted usage throughout
|
|
* the library, this check is a good opportunity to
|
|
* validate this. */
|
|
MBEDTLS_MPS_TRACE_RETURN(
|
|
MBEDTLS_ERR_MPS_READER_INCONSISTENT_REQUESTS );
|
|
}
|
|
}
|
|
|
|
acc = rd->acc;
|
|
acc += end;
|
|
|
|
*buffer = acc;
|
|
if( buflen != NULL )
|
|
*buflen = desired;
|
|
|
|
end += desired;
|
|
rd->end = end;
|
|
rd->pending = 0;
|
|
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
/* Attempt to serve the request from the current fragment */
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Serve the request from the current fragment." );
|
|
|
|
frag_len = rd->frag_len;
|
|
frag_fetched = end - frag_offset; /* The amount of data from the current
|
|
* fragment that has already been passed
|
|
* to the user. */
|
|
frag_remaining = frag_len - frag_fetched; /* Remaining data in fragment */
|
|
|
|
/* Check if we can serve the read request from the fragment. */
|
|
if( frag_remaining < desired )
|
|
{
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"There's not enough data in the current fragment "
|
|
"to serve the request." );
|
|
/* There's not enough data in the current fragment,
|
|
* so either just RETURN what we have or fail. */
|
|
if( buflen == NULL )
|
|
{
|
|
if( frag_remaining > 0 )
|
|
{
|
|
rd->pending = desired - frag_remaining;
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Remember to collect %u bytes before re-opening",
|
|
(unsigned) rd->pending );
|
|
}
|
|
MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_READER_OUT_OF_DATA );
|
|
}
|
|
|
|
desired = frag_remaining;
|
|
}
|
|
|
|
/* There's enough data in the current fragment to serve the
|
|
* (potentially modified) read request. */
|
|
|
|
frag = rd->frag;
|
|
frag += frag_fetched;
|
|
|
|
*buffer = frag;
|
|
if( buflen != NULL )
|
|
*buflen = desired;
|
|
|
|
end += desired;
|
|
rd->end = end;
|
|
rd->pending = 0;
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
int mbedtls_mps_reader_commit( mbedtls_mps_reader *rd )
|
|
{
|
|
mbedtls_mps_size_t end;
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_commit" );
|
|
MBEDTLS_MPS_STATE_VALIDATE_RAW( mps_reader_is_consuming( rd ),
|
|
"mbedtls_mps_reader_commit() requires reader to be in consuming mode" );
|
|
|
|
end = rd->end;
|
|
rd->commit = end;
|
|
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|
|
|
|
int mbedtls_mps_reader_reclaim( mbedtls_mps_reader *rd,
|
|
int *paused )
|
|
{
|
|
unsigned char *frag, *acc;
|
|
mbedtls_mps_size_t pending, commit;
|
|
mbedtls_mps_size_t acc_len, frag_offset, frag_len;
|
|
MBEDTLS_MPS_TRACE_INIT( "mbedtls_mps_reader_reclaim" );
|
|
|
|
if( paused != NULL )
|
|
*paused = 0;
|
|
|
|
MBEDTLS_MPS_STATE_VALIDATE_RAW( mps_reader_is_consuming( rd ),
|
|
"mbedtls_mps_reader_reclaim() requires reader to be in consuming mode" );
|
|
|
|
frag = rd->frag;
|
|
acc = rd->acc;
|
|
pending = rd->pending;
|
|
commit = rd->commit;
|
|
frag_len = rd->frag_len;
|
|
|
|
frag_offset = mps_reader_get_fragment_offset( rd );
|
|
|
|
if( pending == 0 )
|
|
{
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"No unsatisfied read-request has been logged." );
|
|
|
|
/* Check if there's data left to be consumed. */
|
|
if( commit < frag_offset || commit - frag_offset < frag_len )
|
|
{
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"There is data left to be consumed." );
|
|
rd->end = commit;
|
|
MBEDTLS_MPS_TRACE_RETURN( MBEDTLS_ERR_MPS_READER_DATA_LEFT );
|
|
}
|
|
|
|
rd->acc_available = 0;
|
|
rd->acc_share.acc_remaining = 0;
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Fragment has been fully processed and committed." );
|
|
}
|
|
else
|
|
{
|
|
int overflow;
|
|
|
|
mbedtls_mps_size_t acc_backup_offset;
|
|
mbedtls_mps_size_t acc_backup_len;
|
|
mbedtls_mps_size_t frag_backup_offset;
|
|
mbedtls_mps_size_t frag_backup_len;
|
|
|
|
mbedtls_mps_size_t backup_len;
|
|
mbedtls_mps_size_t acc_len_needed;
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"There has been an unsatisfied read with %u bytes overhead.",
|
|
(unsigned) pending );
|
|
|
|
if( acc == NULL )
|
|
{
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"No accumulator present" );
|
|
MBEDTLS_MPS_TRACE_RETURN(
|
|
MBEDTLS_ERR_MPS_READER_NEED_ACCUMULATOR );
|
|
}
|
|
acc_len = rd->acc_len;
|
|
|
|
/* Check if the upper layer has already fetched
|
|
* and committed the contents of the accumulator. */
|
|
if( commit < frag_offset )
|
|
{
|
|
/* No, accumulator is still being processed. */
|
|
frag_backup_offset = 0;
|
|
frag_backup_len = frag_len;
|
|
acc_backup_offset = commit;
|
|
acc_backup_len = frag_offset - commit;
|
|
}
|
|
else
|
|
{
|
|
/* Yes, the accumulator is already processed. */
|
|
frag_backup_offset = commit - frag_offset;
|
|
frag_backup_len = frag_len - frag_backup_offset;
|
|
acc_backup_offset = 0;
|
|
acc_backup_len = 0;
|
|
}
|
|
|
|
backup_len = acc_backup_len + frag_backup_len;
|
|
acc_len_needed = backup_len + pending;
|
|
|
|
overflow = 0;
|
|
overflow |= ( backup_len < acc_backup_len );
|
|
overflow |= ( acc_len_needed < backup_len );
|
|
|
|
if( overflow || acc_len < acc_len_needed )
|
|
{
|
|
/* Except for the different return code, we behave as if
|
|
* there hadn't been a call to mbedtls_mps_reader_get()
|
|
* since the last commit. */
|
|
rd->end = commit;
|
|
rd->pending = 0;
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_error,
|
|
"The accumulator is too small to handle the backup." );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_error,
|
|
"* Size: %u", (unsigned) acc_len );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_error,
|
|
"* Needed: %u (%u + %u)",
|
|
(unsigned) acc_len_needed,
|
|
(unsigned) backup_len, (unsigned) pending );
|
|
MBEDTLS_MPS_TRACE_RETURN(
|
|
MBEDTLS_ERR_MPS_READER_ACCUMULATOR_TOO_SMALL );
|
|
}
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Fragment backup: %u", (unsigned) frag_backup_len );
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Accumulator backup: %u", (unsigned) acc_backup_len );
|
|
|
|
/* Move uncommitted parts from the accumulator to the front
|
|
* of the accumulator. */
|
|
memmove( acc, acc + acc_backup_offset, acc_backup_len );
|
|
|
|
/* Copy uncmmitted parts of the current fragment to the
|
|
* accumulator. */
|
|
memcpy( acc + acc_backup_len,
|
|
frag + frag_backup_offset, frag_backup_len );
|
|
|
|
rd->acc_available = backup_len;
|
|
rd->acc_share.acc_remaining = pending;
|
|
|
|
if( paused != NULL )
|
|
*paused = 1;
|
|
}
|
|
|
|
rd->frag = NULL;
|
|
rd->frag_len = 0;
|
|
|
|
rd->commit = 0;
|
|
rd->end = 0;
|
|
rd->pending = 0;
|
|
|
|
MBEDTLS_MPS_TRACE( mbedtls_mps_trace_comment,
|
|
"Final state: aa %u, al %u, ar %u",
|
|
(unsigned) rd->acc_available, (unsigned) rd->acc_len,
|
|
(unsigned) rd->acc_share.acc_remaining );
|
|
MBEDTLS_MPS_TRACE_RETURN( 0 );
|
|
}
|