From f1e2ca801c54dfc09d6a5540207cec25e8d43f6f Mon Sep 17 00:00:00 2001 From: Kuan-Wei Chiu Date: Fri, 14 Nov 2025 14:00:45 +0800 Subject: lib/base64: add support for multiple variants Patch series " lib/base64: add generic encoder/decoder, migrate users", v5. This series introduces a generic Base64 encoder/decoder to the kernel library, eliminating duplicated implementations and delivering significant performance improvements. The Base64 API has been extended to support multiple variants (Standard, URL-safe, and IMAP) as defined in RFC 4648 and RFC 3501. The API now takes a variant parameter and an option to control padding. As part of this series, users are migrated to the new interface while preserving their specific formats: fscrypt now uses BASE64_URLSAFE, Ceph uses BASE64_IMAP, and NVMe is updated to BASE64_STD. On the encoder side, the implementation processes input in 3-byte blocks, mapping 24 bits directly to 4 output symbols. This avoids bit-by-bit streaming and reduces loop overhead, achieving about a 2.7x speedup compared to previous implementations. On the decoder side, replace strchr() lookups with per-variant reverse tables and process input in 4-character groups. Each group is mapped to numeric values and combined into 3 bytes. Padded and unpadded forms are validated explicitly, rejecting invalid '=' usage and enforcing tail rules. This improves throughput by ~43-52x. This patch (of 6): Extend the base64 API to support multiple variants (standard, URL-safe, and IMAP) as defined in RFC 4648 and RFC 3501. The API now takes a variant parameter and an option to control padding. Update NVMe auth code to use the new interface with BASE64_STD. Link: https://lkml.kernel.org/r/20251114055829.87814-1-409411716@gms.tku.edu.tw Link: https://lkml.kernel.org/r/20251114060045.88792-1-409411716@gms.tku.edu.tw Signed-off-by: Kuan-Wei Chiu Co-developed-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw> Reviewed-by: David Laight Cc: Christoph Hellwig 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 --- include/linux/base64.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/base64.h b/include/linux/base64.h index 660d4cb1ef31..a2c6c9222da3 100644 --- a/include/linux/base64.h +++ b/include/linux/base64.h @@ -8,9 +8,15 @@ #include +enum base64_variant { + BASE64_STD, /* RFC 4648 (standard) */ + BASE64_URLSAFE, /* RFC 4648 (base64url) */ + BASE64_IMAP, /* RFC 3501 */ +}; + #define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) -int base64_encode(const u8 *src, int len, char *dst); -int base64_decode(const char *src, int len, u8 *dst); +int base64_encode(const u8 *src, int len, char *dst, bool padding, enum base64_variant variant); +int base64_decode(const char *src, int len, u8 *dst, bool padding, enum base64_variant variant); #endif /* _LINUX_BASE64_H */ -- cgit