feedc0de/wolfssl
1
0
Fork 0
forked from wolfSSL/wolfssl
Code Pull Requests Activity

tls: refactoring doPRF to reduce stack usage:

Browse Source 
--- variable md5_hash moved to the heap (up to 256 bytes saved)
--- variable sha_hash moved to the heap (up to 256 bytes saved)
--- variable labelSeed moved to the heap (up to 128 bytes saved)
--- variable md5_result moved to the heap (up to 224 bytes saved)
--- variable sha_result moved to the heap (up to 224 bytes saved)

tls: refactoring PRF to reduce stack usage:
--- variable labelSeed moved to the heap (up to 128 bytes saved)
This commit is contained in:
Moisés Guimarães
2014-07-29 13:15:28 -03:00
parent e3db86753c
commit 0283a917e8
1 changed files with 66 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

84
src/tls.c
View File

@ -190,14 +190,22 @@ static int doPRF(byte* digest, word32 digLen, const byte* secret,word32 secLen,
const byte* label, word32 labLen, const byte* seed,
word32 seedLen)
{
int ret;
int ret = 0;
word32 half = (secLen + 1) / 2;
byte md5_half[MAX_PRF_HALF]; /* half is real size */
byte sha_half[MAX_PRF_HALF]; /* half is real size */
byte labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
byte md5_result[MAX_PRF_DIG]; /* digLen is real size */
byte sha_result[MAX_PRF_DIG]; /* digLen is real size */
#ifdef CYASSL_SMALL_STACK
byte* md5_half;
byte* sha_half;
byte* labelSeed;
byte* md5_result;
byte* sha_result;
#else
byte md5_half[MAX_PRF_HALF]; /* half is real size */
byte sha_half[MAX_PRF_HALF]; /* half is real size */
byte labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
byte md5_result[MAX_PRF_DIG]; /* digLen is real size */
byte sha_result[MAX_PRF_DIG]; /* digLen is real size */
#endif
if (half > MAX_PRF_HALF)
return BUFFER_E;
@ -206,26 +214,51 @@ static int doPRF(byte* digest, word32 digLen, const byte* secret,word32 secLen,
if (digLen > MAX_PRF_DIG)
return BUFFER_E;
#ifdef CYASSL_SMALL_STACK
md5_half = (byte*)XMALLOC(MAX_PRF_HALF, NULL, DYNAMIC_TYPE_TMP_BUFFER);
sha_half = (byte*)XMALLOC(MAX_PRF_HALF, NULL, DYNAMIC_TYPE_TMP_BUFFER);
labelSeed = (byte*)XMALLOC(MAX_PRF_LABSEED, NULL, DYNAMIC_TYPE_TMP_BUFFER);
md5_result = (byte*)XMALLOC(MAX_PRF_DIG, NULL, DYNAMIC_TYPE_TMP_BUFFER);
sha_result = (byte*)XMALLOC(MAX_PRF_DIG, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (md5_half == NULL || sha_half == NULL || labelSeed == NULL ||
md5_result == NULL || sha_result == NULL) {
if (md5_half) XFREE(md5_half, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (sha_half) XFREE(sha_half, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (labelSeed) XFREE(labelSeed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (md5_result) XFREE(md5_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
if (sha_result) XFREE(sha_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
return MEMORY_E;
}
#endif
XMEMSET(md5_result, 0, digLen);
XMEMSET(sha_result, 0, digLen);
XMEMCPY(md5_half, secret, half);
XMEMCPY(sha_half, secret + half - secLen % 2, half);
XMEMCPY(labelSeed, label, labLen);
XMEMCPY(labelSeed + labLen, seed, seedLen);
ret = p_hash(md5_result, digLen, md5_half, half, labelSeed,
labLen + seedLen, md5_mac);
if (ret != 0)
return ret;
ret = p_hash(sha_result, digLen, sha_half, half, labelSeed,
labLen + seedLen, sha_mac);
if (ret != 0)
return ret;
get_xor(digest, digLen, md5_result, sha_result);
if ((ret = p_hash(md5_result, digLen, md5_half, half, labelSeed,
labLen + seedLen, md5_mac)) == 0) {
if ((ret = p_hash(sha_result, digLen, sha_half, half, labelSeed,
labLen + seedLen, sha_mac)) == 0) {
get_xor(digest, digLen, md5_result, sha_result);
}
}
return 0;
#ifdef CYASSL_SMALL_STACK
XFREE(md5_half, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(sha_half, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(labelSeed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(md5_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
XFREE(sha_result, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
return ret;
}
#endif
@ -240,10 +273,21 @@ static int PRF(byte* digest, word32 digLen, const byte* secret, word32 secLen,
int ret = 0;
if (useAtLeastSha256) {
byte labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
#ifdef CYASSL_SMALL_STACK
byte* labelSeed;
#else
byte labelSeed[MAX_PRF_LABSEED]; /* labLen + seedLen is real size */
#endif
if (labLen + seedLen > MAX_PRF_LABSEED)
return BUFFER_E;
#ifdef CYASSL_SMALL_STACK
labelSeed = (byte*)XMALLOC(MAX_PRF_LABSEED, NULL,
DYNAMIC_TYPE_TMP_BUFFER);
if (labelSeed == NULL)
return MEMORY_E;
#endif
XMEMCPY(labelSeed, label, labLen);
XMEMCPY(labelSeed + labLen, seed, seedLen);
@ -254,6 +298,10 @@ static int PRF(byte* digest, word32 digLen, const byte* secret, word32 secLen,
hash_type = sha256_mac;
ret = p_hash(digest, digLen, secret, secLen, labelSeed,
labLen + seedLen, hash_type);
#ifdef CYASSL_SMALL_STACK
XFREE(labelSeed, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
}
#ifndef NO_OLD_TLS
else {