From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- lib/crypto/chacha20poly1305.c | 361 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 361 insertions(+) create mode 100644 lib/crypto/chacha20poly1305.c (limited to 'lib/crypto/chacha20poly1305.c') diff --git a/lib/crypto/chacha20poly1305.c b/lib/crypto/chacha20poly1305.c new file mode 100644 index 000000000..ea42a28f4 --- /dev/null +++ b/lib/crypto/chacha20poly1305.c @@ -0,0 +1,361 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT +/* + * Copyright (C) 2015-2019 Jason A. Donenfeld . All Rights Reserved. + * + * This is an implementation of the ChaCha20Poly1305 AEAD construction. + * + * Information: https://tools.ietf.org/html/rfc8439 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void chacha_load_key(u32 *k, const u8 *in) +{ + k[0] = get_unaligned_le32(in); + k[1] = get_unaligned_le32(in + 4); + k[2] = get_unaligned_le32(in + 8); + k[3] = get_unaligned_le32(in + 12); + k[4] = get_unaligned_le32(in + 16); + k[5] = get_unaligned_le32(in + 20); + k[6] = get_unaligned_le32(in + 24); + k[7] = get_unaligned_le32(in + 28); +} + +static void xchacha_init(struct chacha_state *chacha_state, + const u8 *key, const u8 *nonce) +{ + u32 k[CHACHA_KEY_WORDS]; + u8 iv[CHACHA_IV_SIZE]; + + memset(iv, 0, 8); + memcpy(iv + 8, nonce + 16, 8); + + chacha_load_key(k, key); + + /* Compute the subkey given the original key and first 128 nonce bits */ + chacha_init(chacha_state, k, nonce); + hchacha_block(chacha_state, k, 20); + + chacha_init(chacha_state, k, iv); + + memzero_explicit(k, sizeof(k)); + memzero_explicit(iv, sizeof(iv)); +} + +static void +__chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + struct chacha_state *chacha_state) +{ + const u8 *pad0 = page_address(ZERO_PAGE(0)); + struct poly1305_desc_ctx poly1305_state; + union { + u8 block0[POLY1305_KEY_SIZE]; + __le64 lens[2]; + } b; + + chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0)); + poly1305_init(&poly1305_state, b.block0); + + poly1305_update(&poly1305_state, ad, ad_len); + if (ad_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf)); + + chacha20_crypt(chacha_state, dst, src, src_len); + + poly1305_update(&poly1305_state, dst, src_len); + if (src_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf)); + + b.lens[0] = cpu_to_le64(ad_len); + b.lens[1] = cpu_to_le64(src_len); + poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens)); + + poly1305_final(&poly1305_state, dst + src_len); + + chacha_zeroize_state(chacha_state); + memzero_explicit(&b, sizeof(b)); +} + +void chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + const u64 nonce, + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + struct chacha_state chacha_state; + u32 k[CHACHA_KEY_WORDS]; + __le64 iv[2]; + + chacha_load_key(k, key); + + iv[0] = 0; + iv[1] = cpu_to_le64(nonce); + + chacha_init(&chacha_state, k, (u8 *)iv); + __chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, + &chacha_state); + + memzero_explicit(iv, sizeof(iv)); + memzero_explicit(k, sizeof(k)); +} +EXPORT_SYMBOL(chacha20poly1305_encrypt); + +void xchacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + const u8 nonce[at_least XCHACHA20POLY1305_NONCE_SIZE], + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + struct chacha_state chacha_state; + + xchacha_init(&chacha_state, key, nonce); + __chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, + &chacha_state); +} +EXPORT_SYMBOL(xchacha20poly1305_encrypt); + +static bool +__chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + struct chacha_state *chacha_state) +{ + const u8 *pad0 = page_address(ZERO_PAGE(0)); + struct poly1305_desc_ctx poly1305_state; + size_t dst_len; + int ret; + union { + u8 block0[POLY1305_KEY_SIZE]; + u8 mac[POLY1305_DIGEST_SIZE]; + __le64 lens[2]; + } b; + + if (unlikely(src_len < POLY1305_DIGEST_SIZE)) + return false; + + chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0)); + poly1305_init(&poly1305_state, b.block0); + + poly1305_update(&poly1305_state, ad, ad_len); + if (ad_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf)); + + dst_len = src_len - POLY1305_DIGEST_SIZE; + poly1305_update(&poly1305_state, src, dst_len); + if (dst_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (dst_len & 0xf)); + + b.lens[0] = cpu_to_le64(ad_len); + b.lens[1] = cpu_to_le64(dst_len); + poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens)); + + poly1305_final(&poly1305_state, b.mac); + + ret = crypto_memneq(b.mac, src + dst_len, POLY1305_DIGEST_SIZE); + if (likely(!ret)) + chacha20_crypt(chacha_state, dst, src, dst_len); + + memzero_explicit(&b, sizeof(b)); + + return !ret; +} + +bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + const u64 nonce, + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + struct chacha_state chacha_state; + u32 k[CHACHA_KEY_WORDS]; + __le64 iv[2]; + bool ret; + + chacha_load_key(k, key); + + iv[0] = 0; + iv[1] = cpu_to_le64(nonce); + + chacha_init(&chacha_state, k, (u8 *)iv); + ret = __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len, + &chacha_state); + + chacha_zeroize_state(&chacha_state); + memzero_explicit(iv, sizeof(iv)); + memzero_explicit(k, sizeof(k)); + return ret; +} +EXPORT_SYMBOL(chacha20poly1305_decrypt); + +bool xchacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, + const u8 *ad, const size_t ad_len, + const u8 nonce[at_least XCHACHA20POLY1305_NONCE_SIZE], + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + struct chacha_state chacha_state; + + xchacha_init(&chacha_state, key, nonce); + return __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len, + &chacha_state); +} +EXPORT_SYMBOL(xchacha20poly1305_decrypt); + +static +bool chacha20poly1305_crypt_sg_inplace(struct scatterlist *src, + const size_t src_len, + const u8 *ad, const size_t ad_len, + const u64 nonce, + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE], + int encrypt) +{ + const u8 *pad0 = page_address(ZERO_PAGE(0)); + struct poly1305_desc_ctx poly1305_state; + struct chacha_state chacha_state; + struct sg_mapping_iter miter; + size_t partial = 0; + unsigned int flags; + bool ret = true; + int sl; + union { + struct { + u32 k[CHACHA_KEY_WORDS]; + __le64 iv[2]; + }; + u8 block0[POLY1305_KEY_SIZE]; + u8 chacha_stream[CHACHA_BLOCK_SIZE]; + struct { + u8 mac[2][POLY1305_DIGEST_SIZE]; + }; + __le64 lens[2]; + } b __aligned(16); + + if (WARN_ON(src_len > INT_MAX)) + return false; + + chacha_load_key(b.k, key); + + b.iv[0] = 0; + b.iv[1] = cpu_to_le64(nonce); + + chacha_init(&chacha_state, b.k, (u8 *)b.iv); + chacha20_crypt(&chacha_state, b.block0, pad0, sizeof(b.block0)); + poly1305_init(&poly1305_state, b.block0); + + if (unlikely(ad_len)) { + poly1305_update(&poly1305_state, ad, ad_len); + if (ad_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf)); + } + + flags = SG_MITER_TO_SG | SG_MITER_ATOMIC; + + sg_miter_start(&miter, src, sg_nents(src), flags); + + for (sl = src_len; sl > 0 && sg_miter_next(&miter); sl -= miter.length) { + u8 *addr = miter.addr; + size_t length = min_t(size_t, sl, miter.length); + + if (!encrypt) + poly1305_update(&poly1305_state, addr, length); + + if (unlikely(partial)) { + size_t l = min(length, CHACHA_BLOCK_SIZE - partial); + + crypto_xor(addr, b.chacha_stream + partial, l); + partial = (partial + l) & (CHACHA_BLOCK_SIZE - 1); + + addr += l; + length -= l; + } + + if (likely(length >= CHACHA_BLOCK_SIZE || length == sl)) { + size_t l = length; + + if (unlikely(length < sl)) + l &= ~(CHACHA_BLOCK_SIZE - 1); + chacha20_crypt(&chacha_state, addr, addr, l); + addr += l; + length -= l; + } + + if (unlikely(length > 0)) { + chacha20_crypt(&chacha_state, b.chacha_stream, pad0, + CHACHA_BLOCK_SIZE); + crypto_xor(addr, b.chacha_stream, length); + partial = length; + } + + if (encrypt) + poly1305_update(&poly1305_state, miter.addr, + min_t(size_t, sl, miter.length)); + } + + if (src_len & 0xf) + poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf)); + + b.lens[0] = cpu_to_le64(ad_len); + b.lens[1] = cpu_to_le64(src_len); + poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens)); + + if (likely(sl <= -POLY1305_DIGEST_SIZE)) { + if (encrypt) { + poly1305_final(&poly1305_state, + miter.addr + miter.length + sl); + ret = true; + } else { + poly1305_final(&poly1305_state, b.mac[0]); + ret = !crypto_memneq(b.mac[0], + miter.addr + miter.length + sl, + POLY1305_DIGEST_SIZE); + } + } + + sg_miter_stop(&miter); + + if (unlikely(sl > -POLY1305_DIGEST_SIZE)) { + poly1305_final(&poly1305_state, b.mac[1]); + sg_copy_buffer(src, sg_nents(src), b.mac[encrypt], + sizeof(b.mac[1]), src_len, !encrypt); + ret = encrypt || + !crypto_memneq(b.mac[0], b.mac[1], POLY1305_DIGEST_SIZE); + } + + chacha_zeroize_state(&chacha_state); + memzero_explicit(&b, sizeof(b)); + + return ret; +} + +bool chacha20poly1305_encrypt_sg_inplace(struct scatterlist *src, size_t src_len, + const u8 *ad, const size_t ad_len, + const u64 nonce, + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + return chacha20poly1305_crypt_sg_inplace(src, src_len, ad, ad_len, + nonce, key, 1); +} +EXPORT_SYMBOL(chacha20poly1305_encrypt_sg_inplace); + +bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len, + const u8 *ad, const size_t ad_len, + const u64 nonce, + const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) +{ + if (unlikely(src_len < POLY1305_DIGEST_SIZE)) + return false; + + return chacha20poly1305_crypt_sg_inplace(src, + src_len - POLY1305_DIGEST_SIZE, + ad, ad_len, nonce, key, 0); +} +EXPORT_SYMBOL(chacha20poly1305_decrypt_sg_inplace); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("ChaCha20Poly1305 AEAD construction"); +MODULE_AUTHOR("Jason A. Donenfeld "); -- cgit v1.3.1