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Add checks for ascii digits in time decode functions #10276

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89 changes: 65 additions & 24 deletions src/ssl_asn1.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4293,6 +4293,14 @@ static int wolfssl_utctime_year(const unsigned char* str, int len, int* year)
ret = 0;
}

if (ret == 1) {
if ((str[0] < '0') || (str[0] > '9') ||
(str[1] < '0') || (str[1] > '9')) {
WOLFSSL_MSG("Invalid characters in UTC year.");
ret = 0;
}
}

if (ret == 1) {
int tm_year;
/* 2-digit year. */
Expand Down Expand Up @@ -4334,6 +4342,16 @@ static int wolfssl_gentime_year(const unsigned char* str, int len, int* year)
ret = 0;
}

if (ret == 1) {
if ((str[0] < '0') || (str[0] > '9') ||
(str[1] < '0') || (str[1] > '9') ||
(str[2] < '0') || (str[2] > '9') ||
(str[3] < '0') || (str[3] > '9')) {
WOLFSSL_MSG("Invalid characters in generalized year.");
ret = 0;
}
}

if (ret == 1) {
int tm_year;
/* 4-digit year. */
Expand Down Expand Up @@ -4363,11 +4381,12 @@ static int wolfssl_asn1_time_to_tm(const WOLFSSL_ASN1_TIME* asnTime,
const unsigned char* asn1TimeBuf;
int asn1TimeBufLen;
int i = 0;
#ifdef XMKTIME
/* Parse into a local struct so the caller's tm is only written on
* success. Avoids leaving a partially-populated struct behind when
* the input fails validation. */
struct tm localTm;

XMEMSET(&localTm, 0, sizeof localTm);
#endif
XMEMSET(&localTm, 0, sizeof(localTm));

/* Get the string buffer - fixed array, can't fail. */
asn1TimeBuf = wolfSSL_ASN1_TIME_get_data(asnTime);
Expand All @@ -4378,15 +4397,12 @@ static int wolfssl_asn1_time_to_tm(const WOLFSSL_ASN1_TIME* asnTime,
ret = 0;
}
if (ret == 1) {
/* Zero out values in broken-down time. */
XMEMSET(tm, 0, sizeof(struct tm));

if (asnTime->type == WOLFSSL_V_ASN1_UTCTIME) {
/* Get year from UTC TIME string. */
int tm_year;
if ((ret = wolfssl_utctime_year(asn1TimeBuf, asn1TimeBufLen,
&tm_year)) == 1) {
tm->tm_year = tm_year;
localTm.tm_year = tm_year;
/* Month starts after year - 2 characters. */
i = 2;
}
Expand All @@ -4396,7 +4412,7 @@ static int wolfssl_asn1_time_to_tm(const WOLFSSL_ASN1_TIME* asnTime,
int tm_year;
if ((ret = wolfssl_gentime_year(asn1TimeBuf, asn1TimeBufLen,
&tm_year)) == 1) {
tm->tm_year = tm_year;
localTm.tm_year = tm_year;
/* Month starts after year - 4 characters. */
i = 4;
}
Expand All @@ -4406,26 +4422,51 @@ static int wolfssl_asn1_time_to_tm(const WOLFSSL_ASN1_TIME* asnTime,
WOLFSSL_MSG("asnTime->type is invalid.");
ret = 0;
}
}
if (ret == 1) {
}

if (ret == 1) {
int j;
/* Validate 10 digits: MMDDHHMMSS. Length was already checked
* (>= UTCTIME_LEN or >= GENTIME_LEN), so i+10 is in range. */
for (j = i; j < i + 10; j++) {
if (asn1TimeBuf[j] < '0' || asn1TimeBuf[j] > '9') {
WOLFSSL_MSG("Non-digit in ASN.1 TIME.");
ret = 0;
break;
}
}
}

if (ret == 1) {
/* Fill in rest of broken-down time from string. */
/* January is 0 not 1 */
tm->tm_mon = (asn1TimeBuf[i] - '0') * 10; i++;
tm->tm_mon += (asn1TimeBuf[i] - '0') - 1; i++;
tm->tm_mday = (asn1TimeBuf[i] - '0') * 10; i++;
tm->tm_mday += (asn1TimeBuf[i] - '0'); i++;
tm->tm_hour = (asn1TimeBuf[i] - '0') * 10; i++;
tm->tm_hour += (asn1TimeBuf[i] - '0'); i++;
tm->tm_min = (asn1TimeBuf[i] - '0') * 10; i++;
tm->tm_min += (asn1TimeBuf[i] - '0'); i++;
tm->tm_sec = (asn1TimeBuf[i] - '0') * 10; i++;
tm->tm_sec += (asn1TimeBuf[i] - '0');
localTm.tm_mon = (asn1TimeBuf[i] - '0') * 10; i++;
localTm.tm_mon += (asn1TimeBuf[i] - '0') - 1; i++;
localTm.tm_mday = (asn1TimeBuf[i] - '0') * 10; i++;
localTm.tm_mday += (asn1TimeBuf[i] - '0'); i++;
localTm.tm_hour = (asn1TimeBuf[i] - '0') * 10; i++;
localTm.tm_hour += (asn1TimeBuf[i] - '0'); i++;
localTm.tm_min = (asn1TimeBuf[i] - '0') * 10; i++;
localTm.tm_min += (asn1TimeBuf[i] - '0'); i++;
localTm.tm_sec = (asn1TimeBuf[i] - '0') * 10; i++;
localTm.tm_sec += (asn1TimeBuf[i] - '0');
}

if (ret == 1) {
/* Range-check broken-down fields. ValidateGmtime returns 0 on
* success. */
if (ValidateGmtime(&localTm)) {
WOLFSSL_MSG("Out-of-range field in ASN.1 TIME.");
ret = 0;
}
}

if (ret == 1) {
/* Publish to caller. */
XMEMCPY(tm, &localTm, sizeof(*tm));
#ifdef XMKTIME
XMEMCPY(&localTm, tm, sizeof(struct tm));
/* Call XMKTIME on tm to get tm_wday and tm_yday fields populated.
Note that localTm is used here to avoid modifying other fields,
such as tm_isdst/tm_gmtoff. */
/* XMKTIME may set tm_isdst/tm_gmtoff on localTm; call after the
* copy so those fields stay zero in the caller's tm. */
XMKTIME(&localTm);
tm->tm_wday = localTm.tm_wday;
tm->tm_yday = localTm.tm_yday;
Expand Down
2 changes: 1 addition & 1 deletion wolfcrypt/src/asn.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14664,7 +14664,7 @@ int GetTimeString(byte* date, int format, char* buf, int len, int dateLen)
#endif /* WOLFSSL_ASN_TIME_STRING */

/* Check time struct for valid values. Returns 0 for success */
static int ValidateGmtime(struct tm* inTime)
int ValidateGmtime(struct tm* inTime)
{
int ret = 1;
if ((inTime != NULL) &&
Expand Down
1 change: 1 addition & 0 deletions wolfssl/wolfcrypt/asn.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2452,6 +2452,7 @@ WOLFSSL_LOCAL int GetFormattedTime_ex(void* currTime, byte* buf, word32 len, byt
WOLFSSL_LOCAL int ExtractDate(const unsigned char* date, unsigned char format,
wolfssl_tm* certTime, int* idx, int len);
WOLFSSL_LOCAL int DateGreaterThan(const struct tm* a, const struct tm* b);
WOLFSSL_LOCAL int ValidateGmtime(struct tm* inTime);
WOLFSSL_LOCAL int wc_ValidateDate(const byte* date, byte format, int dateType,
int len);
#ifndef NO_ASN_TIME
Expand Down
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