From: Guan-Chun Wu <409411716@gms.tku.edu.tw> Date: Fri, 14 Nov 2025 06:02:21 +0000 (+0800) Subject: fscrypt: replace local base64url helpers with lib/base64 X-Git-Tag: v6.19-rc1~70^2~67 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7794510e2021a29095721e59f3d249d8b4242fb4;p=thirdparty%2Flinux.git fscrypt: replace local base64url helpers with lib/base64 Replace the base64url encoding and decoding functions in fscrypt with the generic base64_encode() and base64_decode() helpers from lib/base64. This removes the custom implementation in fscrypt, reduces code duplication, and relies on the shared Base64 implementation in lib. The helpers preserve RFC 4648-compliant URL-safe Base64 encoding without padding, so there are no functional changes. This change also improves performance: encoding is about 2.7x faster and decoding achieves 43-52x speedups compared to the previous implementation. Link: https://lkml.kernel.org/r/20251114060221.89734-1-409411716@gms.tku.edu.tw Reviewed-by: Kuan-Wei Chiu Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Cc: Christoph Hellwig Cc: David Laight Cc: Eric Biggers Cc: Ilya Dryomov Cc: Jaegeuk Kim Cc: Jens Axboe Cc: Keith Busch Cc: Sagi Grimberg Cc: "Theodore Y. Ts'o" Cc: Viacheslav Dubeyko Cc: Xiubo Li Cc: Yu-Sheng Huang Signed-off-by: Andrew Morton --- diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 8e4c213d418bd..a9a4432d12ba1 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "fscrypt_private.h" @@ -71,7 +72,7 @@ struct fscrypt_nokey_name { /* Encoded size of max-size no-key name */ #define FSCRYPT_NOKEY_NAME_MAX_ENCODED \ - FSCRYPT_BASE64URL_CHARS(FSCRYPT_NOKEY_NAME_MAX) + BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX) static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) { @@ -162,84 +163,6 @@ static int fname_decrypt(const struct inode *inode, return 0; } -static const char base64url_table[65] = - "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; - -#define FSCRYPT_BASE64URL_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) - -/** - * fscrypt_base64url_encode() - base64url-encode some binary data - * @src: the binary data to encode - * @srclen: the length of @src in bytes - * @dst: (output) the base64url-encoded string. Not NUL-terminated. - * - * Encodes data using base64url encoding, i.e. the "Base 64 Encoding with URL - * and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't used, - * as it's unneeded and not required by the RFC. base64url is used instead of - * base64 to avoid the '/' character, which isn't allowed in filenames. - * - * Return: the length of the resulting base64url-encoded string in bytes. - * This will be equal to FSCRYPT_BASE64URL_CHARS(srclen). - */ -static int fscrypt_base64url_encode(const u8 *src, int srclen, char *dst) -{ - u32 ac = 0; - int bits = 0; - int i; - char *cp = dst; - - for (i = 0; i < srclen; i++) { - ac = (ac << 8) | src[i]; - bits += 8; - do { - bits -= 6; - *cp++ = base64url_table[(ac >> bits) & 0x3f]; - } while (bits >= 6); - } - if (bits) - *cp++ = base64url_table[(ac << (6 - bits)) & 0x3f]; - return cp - dst; -} - -/** - * fscrypt_base64url_decode() - base64url-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 - * - * Decodes a string using base64url encoding, i.e. the "Base 64 Encoding with - * URL and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't - * accepted, nor are non-encoding characters such as whitespace. - * - * 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 base64url string. - */ -static int fscrypt_base64url_decode(const char *src, int srclen, u8 *dst) -{ - u32 ac = 0; - int bits = 0; - int i; - u8 *bp = dst; - - for (i = 0; i < srclen; i++) { - const char *p = strchr(base64url_table, src[i]); - - if (p == NULL || src[i] == 0) - return -1; - ac = (ac << 6) | (p - base64url_table); - bits += 6; - if (bits >= 8) { - bits -= 8; - *bp++ = (u8)(ac >> bits); - } - } - if (ac & ((1 << bits) - 1)) - return -1; - return bp - dst; -} - bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, u32 orig_len, u32 max_len, u32 *encrypted_len_ret) @@ -387,8 +310,8 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode, nokey_name.sha256); size = FSCRYPT_NOKEY_NAME_MAX; } - oname->len = fscrypt_base64url_encode((const u8 *)&nokey_name, size, - oname->name); + oname->len = base64_encode((const u8 *)&nokey_name, size, + oname->name, false, BASE64_URLSAFE); return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); @@ -467,8 +390,8 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, if (fname->crypto_buf.name == NULL) return -ENOMEM; - ret = fscrypt_base64url_decode(iname->name, iname->len, - fname->crypto_buf.name); + ret = base64_decode(iname->name, iname->len, + fname->crypto_buf.name, false, BASE64_URLSAFE); if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) || (ret > offsetof(struct fscrypt_nokey_name, sha256) && ret != FSCRYPT_NOKEY_NAME_MAX)) {