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DTLS Sequence Window Tracking Update

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1. Modify the DTLS sequence window to use an array of word32 instead
   of a word32 or word64 depending on the availability of word64.
2. One can change the array size to have a bigger window.
This commit is contained in:
John Safranek
2016-11-16 12:19:33 -08:00
parent b380eef3e2
commit 2507c4da8a
2 changed files with 57 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
src/internal.c
View File

@@ -7831,7 +7831,7 @@ static int DoHandShakeMsg(WOLFSSL* ssl, byte* input, word32* inOutIdx,
static INLINE int DtlsCheckWindow(WOLFSSL* ssl)
{
DtlsSeq window;
word32* window;
word16 cur_hi, next_hi;
word32 cur_lo, next_lo, diff;
int curLT;
@@ -7869,23 +7869,28 @@ static INLINE int DtlsCheckWindow(WOLFSSL* ssl)
}
/* Check to see that the next value is greater than the number of messages
* trackable in the window (32 or 64), and that the difference between the
* next expected sequence number and the received sequence number is
* inside the window. */
* trackable in the window, and that the difference between the next
* expected sequence number and the received sequence number is inside the
* window. */
if ((next_hi || next_lo > DTLS_SEQ_BITS) &&
curLT && (diff > DTLS_SEQ_BITS)) {
WOLFSSL_MSG("Current record sequence number from the past.");
return 0;
}
else if (curLT && (window & ((DtlsSeq)1 << (diff - 1)))) {
WOLFSSL_MSG("Current record sequence number already received.");
return 0;
}
else if (!curLT && (diff > DTLS_SEQ_BITS)) {
WOLFSSL_MSG("Rejecting message too far into the future.");
return 0;
}
else if (curLT) {
word32 idx = diff / DTLS_WORD_BITS;
word32 newDiff = diff % DTLS_WORD_BITS;
if (window[idx] & (1 << (newDiff - 1))) {
WOLFSSL_MSG("Current record sequence number already received.");
return 0;
}
}
return 1;
}
@@ -7893,7 +7898,7 @@ static INLINE int DtlsCheckWindow(WOLFSSL* ssl)
static INLINE int DtlsUpdateWindow(WOLFSSL* ssl)
{
DtlsSeq* window;
word32* window;
word32* next_lo;
word16* next_hi;
int curLT;
@@ -7903,12 +7908,12 @@ static INLINE int DtlsUpdateWindow(WOLFSSL* ssl)
if (ssl->keys.curEpoch == ssl->keys.nextEpoch) {
next_hi = &ssl->keys.nextSeq_hi;
next_lo = &ssl->keys.nextSeq_lo;
window = &ssl->keys.window;
window = ssl->keys.window;
}
else {
next_hi = &ssl->keys.prevSeq_hi;
next_lo = &ssl->keys.prevSeq_lo;
window = &ssl->keys.prevWindow;
window = ssl->keys.prevWindow;
}
cur_hi = ssl->keys.curSeq_hi;
@@ -7924,14 +7929,36 @@ static INLINE int DtlsUpdateWindow(WOLFSSL* ssl)
}
if (curLT) {
*window |= ((DtlsSeq)1 << (diff - 1));
word32 idx = diff / DTLS_WORD_BITS;
word32 newDiff = diff % DTLS_WORD_BITS;
window[idx] |= (1 << (newDiff - 1));
}
else {
if (diff >= DTLS_SEQ_BITS)
*window = 0;
else
*window <<= (1 + diff);
*window |= 1;
XMEMSET(window, 0, DTLS_SEQ_SZ);
else {
word32 idx, newDiff, temp, i;
word32 oldWindow[WOLFSSL_DTLS_WINDOW_WORDS];
temp = 0;
diff++;
idx = diff / DTLS_WORD_BITS;
newDiff = diff % DTLS_WORD_BITS;
XMEMCPY(oldWindow, window, sizeof(oldWindow));
for (i = 0; i < WOLFSSL_DTLS_WINDOW_WORDS; i++) {
if (i < idx)
window[i] = 0;
else {
temp |= (oldWindow[i-idx] << newDiff);
window[i] = temp;
temp = oldWindow[i-idx] >> (DTLS_WORD_BITS - newDiff);
}
}
}
window[0] |= 1;
*next_lo = cur_lo + 1;
if (*next_lo < cur_lo)
(*next_hi)++;
@@ -9597,8 +9624,9 @@ int ProcessReply(WOLFSSL* ssl)
DtlsMsgPoolReset(ssl);
ssl->keys.nextEpoch++;
ssl->keys.nextSeq_lo = 0;
ssl->keys.prevWindow = ssl->keys.window;
ssl->keys.window = 0;
XMEMCPY(ssl->keys.prevWindow, ssl->keys.window,
DTLS_SEQ_SZ);
XMEMSET(ssl->keys.window, 0, DTLS_SEQ_SZ);
}
#endif

19
wolfssl/internal.h
View File

@@ -1584,12 +1584,13 @@ typedef struct WOLFSSL_DTLS_CTX {
#ifdef WOLFSSL_DTLS
#ifdef WORD64_AVAILABLE
typedef word64 DtlsSeq;
#else
typedef word32 DtlsSeq;
#endif
#define DTLS_SEQ_BITS (sizeof(DtlsSeq) * CHAR_BIT)
#ifndef WOLFSSL_DTLS_WINDOW_WORDS
#define WOLFSSL_DTLS_WINDOW_WORDS 2
#endif /* WOLFSSL_DTLS_WINDOW_WORDS */
#define DTLS_WORD_BITS (sizeof(word32) * CHAR_BIT)
#define DTLS_SEQ_BITS (WOLFSSL_DTLS_WINDOW_WORDS * DTLS_WORD_BITS)
#define DTLS_SEQ_SZ (sizeof(word32) * WOLFSSL_DTLS_WINDOW_WORDS)
#endif /* WOLFSSL_DTLS */
@@ -1617,7 +1618,8 @@ typedef struct Keys {
word32 sequence_number_lo;
#ifdef WOLFSSL_DTLS
DtlsSeq window; /* Sliding window for current epoch */
word32 window[WOLFSSL_DTLS_WINDOW_WORDS];
/* Sliding window for current epoch */
word16 nextEpoch; /* Expected epoch in next record */
word16 nextSeq_hi; /* Expected sequence in next record */
word32 nextSeq_lo;
@@ -1626,7 +1628,8 @@ typedef struct Keys {
word16 curSeq_hi; /* Received sequence in current record */
word32 curSeq_lo;
DtlsSeq prevWindow; /* Sliding window for old epoch */
word32 prevWindow[WOLFSSL_DTLS_WINDOW_WORDS];
/* Sliding window for old epoch */
word16 prevSeq_hi; /* Next sequence in allowed old epoch */
word32 prevSeq_lo;