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 --- crypto/dh_helper.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 crypto/dh_helper.c (limited to 'crypto/dh_helper.c') diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c new file mode 100644 index 000000000..2d4998793 --- /dev/null +++ b/crypto/dh_helper.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2016, Intel Corporation + * Authors: Salvatore Benedetto + */ +#include +#include +#include +#include +#include +#include + +#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int)) + +static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size) +{ + if (!dst || size > end - dst) + return NULL; + memcpy(dst, src, size); + return dst + size; +} + +static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size) +{ + memcpy(dst, src, size); + return src + size; +} + +static inline unsigned int dh_data_size(const struct dh *p) +{ + return p->key_size + p->p_size + p->g_size; +} + +unsigned int crypto_dh_key_len(const struct dh *p) +{ + return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p); +} +EXPORT_SYMBOL_GPL(crypto_dh_key_len); + +int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) +{ + u8 *ptr = buf; + u8 * const end = ptr + len; + struct kpp_secret secret = { + .type = CRYPTO_KPP_SECRET_TYPE_DH, + .len = len + }; + + if (unlikely(!len)) + return -EINVAL; + + ptr = dh_pack_data(ptr, end, &secret, sizeof(secret)); + ptr = dh_pack_data(ptr, end, ¶ms->key_size, + sizeof(params->key_size)); + ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size)); + ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size)); + ptr = dh_pack_data(ptr, end, params->key, params->key_size); + ptr = dh_pack_data(ptr, end, params->p, params->p_size); + ptr = dh_pack_data(ptr, end, params->g, params->g_size); + if (ptr != end) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_encode_key); + +int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + const u8 *ptr = buf; + struct kpp_secret secret; + + if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE)) + return -EINVAL; + + ptr = dh_unpack_data(&secret, ptr, sizeof(secret)); + if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH) + return -EINVAL; + + ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size)); + ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size)); + ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size)); + if (secret.len != crypto_dh_key_len(params)) + return -EINVAL; + + /* Don't allocate memory. Set pointers to data within + * the given buffer + */ + params->key = (void *)ptr; + params->p = (void *)(ptr + params->key_size); + params->g = (void *)(ptr + params->key_size + params->p_size); + + return 0; +} + +int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + int err; + + err = __crypto_dh_decode_key(buf, len, params); + if (err) + return err; + + /* + * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since + * some drivers assume otherwise. + */ + if (params->key_size > params->p_size || + params->g_size > params->p_size) + return -EINVAL; + + /* + * Don't permit 'p' to be 0. It's not a prime number, and it's subject + * to corner cases such as 'mod 0' being undefined or + * crypto_kpp_maxsize() returning 0. + */ + if (memchr_inv(params->p, 0, params->p_size) == NULL) + return -EINVAL; + + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_decode_key); -- cgit v1.3.1