1 files changed, 36 insertions, 26 deletions
diff --git a/lib/base64.c b/lib/base64.c
index b736a7a431c50e..a7c20a8e8e9874 100644
--- a/lib/base64.c
+++ b/lib/base64.c
@@ -1,12 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * base64.c - RFC4648-compliant base64 encoding
+ * base64.c - Base64 with support for multiple variants
  *
  * Copyright (c) 2020 Hannes Reinecke, SUSE
  *
  * Based on the base64url routines from fs/crypto/fname.c
- * (which are using the URL-safe base64 encoding),
- * modified to use the standard coding table from RFC4648 section 4.
+ * (which are using the URL-safe Base64 encoding),
+ * modified to support multiple Base64 variants.
  */
 
 #include <linux/kernel.h>
@@ -15,26 +15,31 @@
 #include <linux/string.h>
 #include <linux/base64.h>
 
-static const char base64_table[65] =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+static const char base64_tables[][65] = {
+	[BASE64_STD] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
+	[BASE64_URLSAFE] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_",
+	[BASE64_IMAP] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,",
+};
 
 /**
- * base64_encode() - base64-encode some binary data
+ * base64_encode() - Base64-encode some binary data
  * @src: the binary data to encode
  * @srclen: the length of @src in bytes
- * @dst: (output) the base64-encoded string.  Not NUL-terminated.
+ * @dst: (output) the Base64-encoded string.  Not NUL-terminated.
+ * @padding: whether to append '=' padding characters
+ * @variant: which base64 variant to use
  *
- * Encodes data using base64 encoding, i.e. the "Base 64 Encoding" specified
- * by RFC 4648, including the  '='-padding.
+ * Encodes data using the selected Base64 variant.
  *
- * Return: the length of the resulting base64-encoded string in bytes.
+ * Return: the length of the resulting Base64-encoded string in bytes.
  */
-int base64_encode(const u8 *src, int srclen, char *dst)
+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];
@@ -48,44 +53,49 @@ int base64_encode(const u8 *src, int srclen, char *dst)
 		*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
 		bits -= 6;
 	}
-	while (bits < 0) {
-		*cp++ = '=';
-		bits += 2;
+	if (padding) {
+		while (bits < 0) {
+			*cp++ = '=';
+			bits += 2;
+		}
 	}
 	return cp - dst;
 }
 EXPORT_SYMBOL_GPL(base64_encode);
 
 /**
- * base64_decode() - base64-decode a string
+ * base64_decode() - Base64-decode a string
  * @src: the string to decode.  Doesn't need to be NUL-terminated.
  * @srclen: the length of @src in bytes
  * @dst: (output) the decoded binary data
+ * @padding: whether to append '=' padding characters
+ * @variant: which base64 variant to use
  *
- * Decodes a string using base64 encoding, i.e. the "Base 64 Encoding"
- * specified by RFC 4648, including the  '='-padding.
+ * 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.
+ *	   or -1 if the string isn't a valid Base64 string.
  */
-int base64_decode(const char *src, int srclen, u8 *dst)
+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;
+	const char *base64_table = base64_tables[variant];
 
 	for (i = 0; i < srclen; i++) {
 		const char *p = strchr(base64_table, src[i]);
-
-		if (src[i] == '=') {
-			ac = (ac << 6);
-			bits += 6;
-			if (bits >= 8)
-				bits -= 8;
-			continue;
+		if (padding) {
+			if (src[i] == '=') {
+				ac = (ac << 6);
+				bits += 6;
+				if (bits >= 8)
+					bits -= 8;
+				continue;
+			}
 		}
 		if (p == NULL || src[i] == 0)
 			return -1;