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8272243: Improve DER parsing

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Reviewed-by: weijun, rhalade
This commit is contained in:
Valerie Peng 2021-09-15 16:39:59 +00:00 • committed by Henry Jen
parent e062dff1bf
commit ddb106be7a
3 changed files with 113 additions and 57 deletions
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30
src/java.base/share/classes/sun/security/util/BitArray.java
View file

@ -65,22 +65,32 @@ public class BitArray {
repn = new byte[(length + BITS_PER_UNIT - 1)/BITS_PER_UNIT];
}
/**
* Creates a BitArray of the specified size, initialized from the
* specified byte array. The most significant bit of {@code a[0]} gets
* index zero in the BitArray. The array must be large enough to specify
* a value for every bit of the BitArray. i.e. {@code 8*a.length <= length}.
*/
public BitArray(int length, byte[] a) throws IllegalArgumentException {
this(length, a, 0);
}
/**
* Creates a BitArray of the specified size, initialized from the
* specified byte array. The most significant bit of {@code a[0]} gets
* index zero in the BitArray. The array a must be large enough
* to specify a value for every bit in the BitArray. In other words,
* {@code 8*a.length <= length}.
* specified byte array starting at the specified offset. The most
* significant bit of {@code a[ofs]} gets index zero in the BitArray.
* The array must be large enough to specify a value for every bit of
* the BitArray, i.e. {@code 8*(a.length - ofs) <= length}.
*/
public BitArray(int length, byte[] a) throws IllegalArgumentException {
public BitArray(int length, byte[] a, int ofs)
throws IllegalArgumentException {
if (length < 0) {
throw new IllegalArgumentException("Negative length for BitArray");
}
if (a.length * BITS_PER_UNIT < length) {
throw new IllegalArgumentException("Byte array too short to represent " +
"bit array of given length");
if ((a.length - ofs) * BITS_PER_UNIT < length) {
throw new IllegalArgumentException
("Byte array too short to represent " + length + "-bit array");
}
this.length = length;
@ -95,7 +105,7 @@ public class BitArray {
2. zero out extra bits in the last byte
*/
repn = new byte[repLength];
System.arraycopy(a, 0, repn, 0, repLength);
System.arraycopy(a, ofs, repn, 0, repLength);
if (repLength > 0) {
repn[repLength - 1] &= bitMask;
}
@ -268,7 +278,7 @@ public class BitArray {
public BitArray truncate() {
for (int i=length-1; i>=0; i--) {
if (get(i)) {
return new BitArray(i+1, Arrays.copyOf(repn, (i + BITS_PER_UNIT)/BITS_PER_UNIT));
return new BitArray(i+1, repn, 0);
}
}
return new BitArray(1);

54
src/java.base/share/classes/sun/security/util/DerValue.java
View file

@ -692,6 +692,28 @@ public class DerValue {
};
}
// check the number of pad bits, validate the pad bits in the bytes
// if enforcing DER (i.e. allowBER == false), and return the number of
// bits of the resulting BitString
private static int checkPaddedBits(int numOfPadBits, byte[] data,
int start, int end, boolean allowBER) throws IOException {
// number of pad bits should be from 0(min) to 7(max).
if ((numOfPadBits < 0) || (numOfPadBits > 7)) {
throw new IOException("Invalid number of padding bits");
}
int lenInBits = ((end - start) << 3) - numOfPadBits;
if (lenInBits < 0) {
throw new IOException("Not enough bytes in BitString");
}
// padding bits should be all zeros for DER
if (!allowBER && numOfPadBits != 0 &&
(data[end - 1] & (0xff >>> (8 - numOfPadBits))) != 0) {
throw new IOException("Invalid value of padding bits");
}
return lenInBits;
}
/**
* Returns an ASN.1 BIT STRING value, with the tag assumed implicit
* based on the parameter. The bit string must be byte-aligned.
@ -708,18 +730,17 @@ public class DerValue {
}
if (end == start) {
throw new IOException("Invalid encoding: zero length bit string");
}
int numOfPadBits = buffer[start];
if ((numOfPadBits < 0) || (numOfPadBits > 7)) {
throw new IOException("Invalid number of padding bits");
}
// minus the first byte which indicates the number of padding bits
byte[] retval = Arrays.copyOfRange(buffer, start + 1, end);
if (numOfPadBits != 0) {
// get rid of the padding bits
retval[end - start - 2] &= (byte)((0xff << numOfPadBits));
}
data.pos = data.end; // Compatibility. Reach end.
int numOfPadBits = buffer[start];
checkPaddedBits(numOfPadBits, buffer, start + 1, end, allowBER);
byte[] retval = Arrays.copyOfRange(buffer, start + 1, end);
if (allowBER && numOfPadBits != 0) {
// fix the potential non-zero padding bits
retval[retval.length - 1] &= (byte)((0xff << numOfPadBits));
}
return retval;
}
@ -742,16 +763,11 @@ public class DerValue {
throw new IOException("Invalid encoding: zero length bit string");
}
data.pos = data.end; // Compatibility. Reach end.
int numOfPadBits = buffer[start];
if ((numOfPadBits < 0) || (numOfPadBits > 7)) {
throw new IOException("Invalid number of padding bits");
}
if (end == start + 1) {
return new BitArray(0);
} else {
return new BitArray(((end - start - 1) << 3) - numOfPadBits,
Arrays.copyOfRange(buffer, start + 1, end));
}
int len = checkPaddedBits(numOfPadBits, buffer, start + 1, end,
allowBER);
return new BitArray(len, buffer, start + 1);
}
/**