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13cecc526d
Consolidate the ChaCha code into a single module (excluding chacha-block-generic.c which remains always built-in for random.c), similar to various other algorithms: - Each arch now provides a header file lib/crypto/$(SRCARCH)/chacha.h, replacing lib/crypto/$(SRCARCH)/chacha*.c. The header defines chacha_crypt_arch() and hchacha_block_arch(). It is included by lib/crypto/chacha.c, and thus the code gets built into the single libchacha module, with improved inlining in some cases. - Whether arch-optimized ChaCha is buildable is now controlled centrally by lib/crypto/Kconfig instead of by lib/crypto/$(SRCARCH)/Kconfig. The conditions for enabling it remain the same as before, and it remains enabled by default. - Any additional arch-specific translation units for the optimized ChaCha code, such as assembly files, are now compiled by lib/crypto/Makefile instead of lib/crypto/$(SRCARCH)/Makefile. This removes the last use for the Makefile and Kconfig files in the arm64, mips, powerpc, riscv, and s390 subdirectories of lib/crypto/. So also remove those files and the references to them. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250827151131.27733-7-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org>
103 lines
3.0 KiB
C
103 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Common values and helper functions for the ChaCha and XChaCha stream ciphers.
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*
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* XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's
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* security. Here they share the same key size, tfm context, and setkey
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* function; only their IV size and encrypt/decrypt function differ.
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*
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* The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is
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* recommended to use the 20-round variant ChaCha20. However, the other
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* variants can be needed in some performance-sensitive scenarios. The generic
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* ChaCha code currently allows only the 20 and 12-round variants.
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*/
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#ifndef _CRYPTO_CHACHA_H
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#define _CRYPTO_CHACHA_H
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#include <linux/unaligned.h>
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#include <linux/string.h>
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#include <linux/types.h>
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/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
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#define CHACHA_IV_SIZE 16
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#define CHACHA_KEY_SIZE 32
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#define CHACHA_BLOCK_SIZE 64
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#define CHACHAPOLY_IV_SIZE 12
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#define CHACHA_KEY_WORDS 8
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#define CHACHA_STATE_WORDS 16
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#define HCHACHA_OUT_WORDS 8
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/* 192-bit nonce, then 64-bit stream position */
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#define XCHACHA_IV_SIZE 32
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struct chacha_state {
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u32 x[CHACHA_STATE_WORDS];
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};
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void chacha_block_generic(struct chacha_state *state,
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u8 out[CHACHA_BLOCK_SIZE], int nrounds);
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static inline void chacha20_block(struct chacha_state *state,
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u8 out[CHACHA_BLOCK_SIZE])
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{
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chacha_block_generic(state, out, 20);
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}
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void hchacha_block_generic(const struct chacha_state *state,
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u32 out[HCHACHA_OUT_WORDS], int nrounds);
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void hchacha_block(const struct chacha_state *state,
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u32 out[HCHACHA_OUT_WORDS], int nrounds);
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enum chacha_constants { /* expand 32-byte k */
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CHACHA_CONSTANT_EXPA = 0x61707865U,
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CHACHA_CONSTANT_ND_3 = 0x3320646eU,
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CHACHA_CONSTANT_2_BY = 0x79622d32U,
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CHACHA_CONSTANT_TE_K = 0x6b206574U
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};
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static inline void chacha_init_consts(struct chacha_state *state)
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{
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state->x[0] = CHACHA_CONSTANT_EXPA;
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state->x[1] = CHACHA_CONSTANT_ND_3;
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state->x[2] = CHACHA_CONSTANT_2_BY;
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state->x[3] = CHACHA_CONSTANT_TE_K;
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}
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static inline void chacha_init(struct chacha_state *state,
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const u32 key[CHACHA_KEY_WORDS],
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const u8 iv[CHACHA_IV_SIZE])
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{
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chacha_init_consts(state);
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state->x[4] = key[0];
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state->x[5] = key[1];
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state->x[6] = key[2];
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state->x[7] = key[3];
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state->x[8] = key[4];
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state->x[9] = key[5];
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state->x[10] = key[6];
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state->x[11] = key[7];
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state->x[12] = get_unaligned_le32(iv + 0);
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state->x[13] = get_unaligned_le32(iv + 4);
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state->x[14] = get_unaligned_le32(iv + 8);
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state->x[15] = get_unaligned_le32(iv + 12);
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}
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void chacha_crypt(struct chacha_state *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds);
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static inline void chacha20_crypt(struct chacha_state *state,
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u8 *dst, const u8 *src, unsigned int bytes)
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{
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chacha_crypt(state, dst, src, bytes, 20);
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}
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static inline void chacha_zeroize_state(struct chacha_state *state)
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{
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memzero_explicit(state, sizeof(*state));
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}
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#endif /* _CRYPTO_CHACHA_H */
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