1 files changed, 68 insertions, 41 deletions

diff --git a/lib/base64.c b/lib/base64.c
index 2d0b775def64..41961a444028 100644
--- a/lib/base64.c
+++ b/lib/base64.c
@@ -80,28 +80,38 @@ static const s8 base64_rev_maps[][256] = {
 int base64_encode(const u8 *src, int srclen, char *dst, bool padding, enum base64_variant variant)
 {
 	u32 ac = 0;
-	int bits = 0;
-	int i;
 	char *cp = dst;
 	const char *base64_table = base64_tables[variant];
 
-	for (i = 0; i < srclen; i++) {
-		ac = (ac << 8) | src[i];
-		bits += 8;
-		do {
-			bits -= 6;
-			*cp++ = base64_table[(ac >> bits) & 0x3f];
-		} while (bits >= 6);
-	}
-	if (bits) {
-		*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
-		bits -= 6;
+	while (srclen >= 3) {
+		ac = src[0] << 16 | src[1] << 8 | src[2];
+		*cp++ = base64_table[ac >> 18];
+		*cp++ = base64_table[(ac >> 12) & 0x3f];
+		*cp++ = base64_table[(ac >> 6) & 0x3f];
+		*cp++ = base64_table[ac & 0x3f];
+
+		src += 3;
+		srclen -= 3;
 	}
-	if (padding) {
-		while (bits < 0) {
+
+	switch (srclen) {
+	case 2:
+		ac = src[0] << 16 | src[1] << 8;
+		*cp++ = base64_table[ac >> 18];
+		*cp++ = base64_table[(ac >> 12) & 0x3f];
+		*cp++ = base64_table[(ac >> 6) & 0x3f];
+		if (padding)
+			*cp++ = '=';
+		break;
+	case 1:
+		ac = src[0] << 16;
+		*cp++ = base64_table[ac >> 18];
+		*cp++ = base64_table[(ac >> 12) & 0x3f];
+		if (padding) {
+			*cp++ = '=';
 			*cp++ = '=';
-			bits += 2;
 		}
+		break;
 	}
 	return cp - dst;
 }
@@ -117,41 +127,58 @@ EXPORT_SYMBOL_GPL(base64_encode);
  *
  * Decodes a string using the selected Base64 variant.
  *
- * This implementation hasn't been optimized for performance.
- *
  * Return: the length of the resulting decoded binary data in bytes,
  *	   or -1 if the string isn't a valid Base64 string.
  */
 int base64_decode(const char *src, int srclen, u8 *dst, bool padding, enum base64_variant variant)
 {
-	u32 ac = 0;
-	int bits = 0;
-	int i;
 	u8 *bp = dst;
-	s8 ch;
+	s8 input[4];
+	s32 val;
+	const u8 *s = (const u8 *)src;
+	const s8 *base64_rev_tables = base64_rev_maps[variant];
 
-	for (i = 0; i < srclen; i++) {
-		if (padding) {
-			if (src[i] == '=') {
-				ac = (ac << 6);
-				bits += 6;
-				if (bits >= 8)
-					bits -= 8;
-				continue;
-			}
-		}
-		ch = base64_rev_maps[variant][(u8)src[i]];
-		if (ch == -1)
-			return -1;
-		ac = (ac << 6) | ch;
-		bits += 6;
-		if (bits >= 8) {
-			bits -= 8;
-			*bp++ = (u8)(ac >> bits);
+	while (srclen >= 4) {
+		input[0] = base64_rev_tables[s[0]];
+		input[1] = base64_rev_tables[s[1]];
+		input[2] = base64_rev_tables[s[2]];
+		input[3] = base64_rev_tables[s[3]];
+
+		val = input[0] << 18 | input[1] << 12 | input[2] << 6 | input[3];
+
+		if (unlikely(val < 0)) {
+			if (!padding || srclen != 4 || s[3] != '=')
+				return -1;
+			padding = 0;
+			srclen = s[2] == '=' ? 2 : 3;
+			break;
 		}
+
+		*bp++ = val >> 16;
+		*bp++ = val >> 8;
+		*bp++ = val;
+
+		s += 4;
+		srclen -= 4;
 	}
-	if (ac & ((1 << bits) - 1))
+
+	if (likely(!srclen))
+		return bp - dst;
+	if (padding || srclen == 1)
 		return -1;
+
+	val = (base64_rev_tables[s[0]] << 12) | (base64_rev_tables[s[1]] << 6);
+	*bp++ = val >> 10;
+
+	if (srclen == 2) {
+		if (val & 0x800003ff)
+			return -1;
+	} else {
+		val |= base64_rev_tables[s[2]];
+		if (val & 0x80000003)
+			return -1;
+		*bp++ = val >> 2;
+	}
 	return bp - dst;
 }
 EXPORT_SYMBOL_GPL(base64_decode);