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[54.68.170.188]) by smtp.gmail.com with ESMTPSA id d5-20020a170902cec500b001b5656b0bf9sm7901984plg.286.2023.07.10.03.23.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jul 2023 03:23:23 -0700 (PDT) From: FUJITA Tomonori To: rust-for-linux@vger.kernel.org, linux-crypto@vger.kernel.org Cc: alex.gaynor@gmail.com, herbert@gondor.apana.org.au, ebiggers@kernel.org, benno.lossin@proton.me Subject: [PATCH v2 2/3] rust: crypto abstractions for random number generator API Date: Mon, 10 Jul 2023 19:22:24 +0900 Message-Id: <20230710102225.155019-3-fujita.tomonori@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230710102225.155019-1-fujita.tomonori@gmail.com> References: <20230710102225.155019-1-fujita.tomonori@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org This patch adds basic abstractions for random number generator API, wrapping crypto_rng structure. Signed-off-by: FUJITA Tomonori --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 12 ++++ rust/kernel/crypto.rs | 1 + rust/kernel/crypto/rng.rs | 101 ++++++++++++++++++++++++++++++++ 4 files changed, 115 insertions(+) create mode 100644 rust/kernel/crypto/rng.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 2f198c6d5de5..089ac38c6461 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -7,6 +7,7 @@ */ #include +#include #include #include #include diff --git a/rust/helpers.c b/rust/helpers.c index 7966902ed8eb..e4dcd611738f 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -19,6 +19,7 @@ */ #include +#include #include #include #include @@ -52,6 +53,17 @@ int rust_helper_crypto_shash_init(struct shash_desc *desc) { return crypto_shash_init(desc); } EXPORT_SYMBOL_GPL(rust_helper_crypto_shash_init); + +void rust_helper_crypto_free_rng(struct crypto_rng *tfm) { + crypto_free_rng(tfm); +} +EXPORT_SYMBOL_GPL(rust_helper_crypto_free_rng); + +int rust_helper_crypto_rng_generate(struct crypto_rng *tfm, const u8 *src, + unsigned int slen, u8 *dst, unsigned int dlen) { + return crypto_rng_generate(tfm, src, slen, dst, dlen); +} +EXPORT_SYMBOL_GPL(rust_helper_crypto_rng_generate); #endif __noreturn void rust_helper_BUG(void) diff --git a/rust/kernel/crypto.rs b/rust/kernel/crypto.rs index f80dd7bd3381..a1995e6c85d4 100644 --- a/rust/kernel/crypto.rs +++ b/rust/kernel/crypto.rs @@ -3,3 +3,4 @@ //! Cryptography. pub mod hash; +pub mod rng; diff --git a/rust/kernel/crypto/rng.rs b/rust/kernel/crypto/rng.rs new file mode 100644 index 000000000000..683f5ee464ce --- /dev/null +++ b/rust/kernel/crypto/rng.rs @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Random number generator. +//! +//! C headers: [`include/crypto/rng.h`](../../../../include/crypto/rng.h) + +use crate::{ + error::{code::EINVAL, from_err_ptr, to_result, Result}, + str::CStr, +}; + +/// Type of Random number generator. +/// +/// # Invariants +/// +/// The pointer is valid. +enum RngType { + /// Uses `crypto_default_rng` + // We don't need to keep an pointer for the default but simpler. + Default(*mut bindings::crypto_rng), + + /// Allocated via `crypto_alloc_rng. + Allocated(*mut bindings::crypto_rng), +} + +/// Corresponds to the kernel's `struct crypto_rng`. +pub struct Rng(RngType); + +impl Drop for Rng { + fn drop(&mut self) { + match self.0 { + RngType::Default(_) => { + // SAFETY: it's safe because `crypto_get_default_rng()` was called during + // the initialization. + unsafe { + bindings::crypto_put_default_rng(); + } + } + RngType::Allocated(ptr) => { + // SAFETY: The type invariants of `RngType` guarantees that the pointer is valid. + unsafe { bindings::crypto_free_rng(ptr) }; + } + } + } +} + +impl Rng { + /// Creates a [`Rng`] instance. + pub fn new(name: &CStr, t: u32, mask: u32) -> Result { + // SAFETY: There are no safety requirements for this FFI call. + let ptr = unsafe { from_err_ptr(bindings::crypto_alloc_rng(name.as_char_ptr(), t, mask)) }?; + // INVARIANT: `ptr` is valid and non-null since `crypto_alloc_rng` + // returned a valid pointer which was null-checked. + Ok(Self(RngType::Allocated(ptr))) + } + + /// Creates a [`Rng`] instance with a default algorithm. + pub fn new_with_default() -> Result { + // SAFETY: There are no safety requirements for this FFI call. + to_result(unsafe { bindings::crypto_get_default_rng() })?; + // INVARIANT: The C API guarantees that `crypto_default_rng` is valid until + // `crypto_put_default_rng` is called. + Ok(Self(RngType::Default(unsafe { + bindings::crypto_default_rng + }))) + } + + /// Get a random number. + pub fn generate(&mut self, src: &[u8], dst: &mut [u8]) -> Result { + if src.len() > u32::MAX as usize || dst.len() > u32::MAX as usize { + return Err(EINVAL); + } + let ptr = match self.0 { + RngType::Default(ptr) => ptr, + RngType::Allocated(ptr) => ptr, + }; + // SAFETY: The type invariants of `RngType' guarantees that the pointer is valid. + to_result(unsafe { + bindings::crypto_rng_generate( + ptr, + src.as_ptr(), + src.len() as u32, + dst.as_mut_ptr(), + dst.len() as u32, + ) + }) + } + + /// Re-initializes the [`Rng`] instance. + pub fn reset(&mut self, seed: &[u8]) -> Result { + if seed.len() > u32::MAX as usize { + return Err(EINVAL); + } + let ptr = match self.0 { + RngType::Default(ptr) => ptr, + RngType::Allocated(ptr) => ptr, + }; + // SAFETY: The type invariants of `RngType' guarantees that the pointer is valid. + to_result(unsafe { bindings::crypto_rng_reset(ptr, seed.as_ptr(), seed.len() as u32) }) + } +}