ML-KEM/ML-DSA part 2: param builder

openssl/src/kdf.rs

@@ -25,15 +25,28 @@ impl Drop for EvpKdfCtx {
 cfg_if::cfg_if! {
     if #[cfg(all(ossl320, not(osslconf = "OPENSSL_NO_ARGON2")))] {
         use std::cmp;
-        use std::ffi::c_void;
         use std::ffi::CStr;
-        use std::mem::MaybeUninit;
         use std::ptr;
         use foreign_types::ForeignTypeRef;
         use libc::c_char;
         use crate::{cvt, cvt_p};
         use crate::lib_ctx::LibCtxRef;
         use crate::error::ErrorStack;
+        use crate::ossl_param::OsslParamBuilder;
+
+        // Safety: these all have null terminators.
+        // We cen remove these CStr::from_bytes_with_nul_unchecked calls
+        // when we upgrade to Rust 1.77+ with literal c"" syntax.
+
+        const OSSL_KDF_PARAM_PASSWORD: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"pass\0") };
+        const OSSL_KDF_PARAM_SALT: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"salt\0") };
+        const OSSL_KDF_PARAM_SECRET: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"secret\0") };
+        const OSSL_KDF_PARAM_ITER: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"iter\0") };
+        const OSSL_KDF_PARAM_SIZE: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"size\0") };
+        const OSSL_KDF_PARAM_THREADS: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"threads\0") };
+        const OSSL_KDF_PARAM_ARGON2_AD: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"ad\0") };
+        const OSSL_KDF_PARAM_ARGON2_LANES: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"lanes\0") };
+        const OSSL_KDF_PARAM_ARGON2_MEMCOST: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"memcost\0") };
 
         #[allow(clippy::too_many_arguments)]
         pub fn argon2d(
@@ -94,72 +107,40 @@ cfg_if::cfg_if! {
             salt: &[u8],
             ad: Option<&[u8]>,
             secret: Option<&[u8]>,
-            mut iter: u32,
-            mut lanes: u32,
-            mut memcost: u32,
+            iter: u32,
+            lanes: u32,
+            memcost: u32,
             out: &mut [u8],
         ) -> Result<(), ErrorStack> {
-            unsafe {
+            let libctx = ctx.map_or(ptr::null_mut(), ForeignTypeRef::as_ptr);
+            let max_threads = unsafe {
                 ffi::init();
-                let libctx = ctx.map_or(ptr::null_mut(), ForeignTypeRef::as_ptr);
-
-                let max_threads = ffi::OSSL_get_max_threads(libctx);
-                let mut threads = 1;
-                // If max_threads is 0, then this isn't a threaded build.
-                // If max_threads is > u32::MAX we need to clamp since
-                // argon2's threads parameter is a u32.
-                if max_threads > 0 {
-                    threads = cmp::min(lanes, cmp::min(max_threads, u32::MAX as u64) as u32);
-                }
-                let mut params: [ffi::OSSL_PARAM; 10] =
-                    core::array::from_fn(|_| MaybeUninit::<ffi::OSSL_PARAM>::zeroed().assume_init());
-                let mut idx = 0;
-                params[idx] = ffi::OSSL_PARAM_construct_octet_string(
-                    b"pass\0".as_ptr() as *const c_char,
-                    pass.as_ptr() as *mut c_void,
-                    pass.len(),
-                );
-                idx += 1;
-                params[idx] = ffi::OSSL_PARAM_construct_octet_string(
-                    b"salt\0".as_ptr() as *const c_char,
-                    salt.as_ptr() as *mut c_void,
-                    salt.len(),
-                );
-                idx += 1;
-                params[idx] =
-                    ffi::OSSL_PARAM_construct_uint(b"threads\0".as_ptr() as *const c_char, &mut threads);
-                idx += 1;
-                params[idx] =
-                    ffi::OSSL_PARAM_construct_uint(b"lanes\0".as_ptr() as *const c_char, &mut lanes);
-                idx += 1;
-                params[idx] =
-                    ffi::OSSL_PARAM_construct_uint(b"memcost\0".as_ptr() as *const c_char, &mut memcost);
-                idx += 1;
-                params[idx] =
-                    ffi::OSSL_PARAM_construct_uint(b"iter\0".as_ptr() as *const c_char, &mut iter);
-                idx += 1;
-                let mut size = out.len() as u32;
-                params[idx] =
-                    ffi::OSSL_PARAM_construct_uint(b"size\0".as_ptr() as *const c_char, &mut size);
-                idx += 1;
-                if let Some(ad) = ad {
-                    params[idx] = ffi::OSSL_PARAM_construct_octet_string(
-                        b"ad\0".as_ptr() as *const c_char,
-                        ad.as_ptr() as *mut c_void,
-                        ad.len(),
-                    );
-                    idx += 1;
-                }
-                if let Some(secret) = secret {
-                    params[idx] = ffi::OSSL_PARAM_construct_octet_string(
-                        b"secret\0".as_ptr() as *const c_char,
-                        secret.as_ptr() as *mut c_void,
-                        secret.len(),
-                    );
-                    idx += 1;
-                }
-                params[idx] = ffi::OSSL_PARAM_construct_end();
-
+                ffi::OSSL_get_max_threads(libctx)
+            };
+            let mut threads = 1;
+            // If max_threads is 0, then this isn't a threaded build.
+            // If max_threads is > u32::MAX we need to clamp since
+            // argon2id's threads parameter is a u32.
+            if max_threads > 0 {
+                threads = cmp::min(lanes, cmp::min(max_threads, u32::MAX as u64) as u32);
+            }
+            let mut bld = OsslParamBuilder::new()?;
+            bld.add_octet_string(OSSL_KDF_PARAM_PASSWORD, pass)?;
+            bld.add_octet_string(OSSL_KDF_PARAM_SALT, salt)?;
+            bld.add_uint(OSSL_KDF_PARAM_THREADS, threads)?;
+            bld.add_uint(OSSL_KDF_PARAM_ARGON2_LANES, lanes)?;
+            bld.add_uint(OSSL_KDF_PARAM_ARGON2_MEMCOST, memcost)?;
+            bld.add_uint(OSSL_KDF_PARAM_ITER, iter)?;
+            let size = out.len() as u32;
+            bld.add_uint(OSSL_KDF_PARAM_SIZE, size)?;
+            if let Some(ad) = ad {
+                bld.add_octet_string(OSSL_KDF_PARAM_ARGON2_AD, ad)?;
+            }
+            if let Some(secret) = secret {
+                bld.add_octet_string(OSSL_KDF_PARAM_SECRET, secret)?;
+            }
+            let params = bld.to_param()?;
+            unsafe {
                 let argon2 = EvpKdf(cvt_p(ffi::EVP_KDF_fetch(
                     libctx,
                     kdf_identifier.as_ptr() as *const c_char,

openssl/src/lib.rs

@@ -177,6 +177,8 @@ pub mod memcmp;
 pub mod nid;
 #[cfg(not(osslconf = "OPENSSL_NO_OCSP"))]
 pub mod ocsp;
+#[cfg(ossl300)]
+mod ossl_param;
 pub mod pkcs12;
 pub mod pkcs5;
 #[cfg(not(any(boringssl, awslc)))]

openssl/src/ossl_param.rs

@@ -0,0 +1,153 @@
+//! OSSL_PARAM management for OpenSSL 3.*
+//!
+//! The OSSL_PARAM structure represents an array of generic
+//! attributes that can represent various
+//! properties in OpenSSL, including keys and operations.
+//!
+//! This is always represented as an array of OSSL_PARAM
+//! structures, terminated by an entry with a NULL key.
+//!
+//! For convinience, the OSSL_PARAM_BLD builder can be used to
+//! dynamically construct these structures.
+//!
+//! Note, that this module is available only in OpenSSL 3.* and
+//! only internally for this crate.
+
+use crate::bn::BigNumRef;
+use crate::error::ErrorStack;
+use crate::{cvt, cvt_p};
+use foreign_types::{ForeignType, ForeignTypeRef};
+use libc::{c_char, c_uint, c_void};
+use openssl_macros::corresponds;
+use std::ffi::CStr;
+
+foreign_type_and_impl_send_sync! {
+    // This is the singular type, but it is always allocated
+    // and used as an array of such types.
+    type CType = ffi::OSSL_PARAM;
+    // OSSL_PARMA_free correctly frees the entire array.
+    fn drop = ffi::OSSL_PARAM_free;
+
+    /// `OsslParamArray` constructed using `OsslParamBuilder`.
+    /// Internally this is a pointer to an array of the OSSL_PARAM
+    /// structures.
+    pub struct OsslParamArray;
+    /// Reference to `OsslParamArray`.
+    pub struct OsslParamArrayRef;
+}
+
+foreign_type_and_impl_send_sync! {
+    type CType = ffi::OSSL_PARAM_BLD;
+    fn drop = ffi::OSSL_PARAM_BLD_free;
+
+    /// Builder used to construct `OsslParamArray`.
+    pub struct OsslParamBuilder;
+    /// Reference to `OsslParamBuilder`.
+    pub struct OsslParamBuilderRef;
+}
+
+impl OsslParamBuilder {
+    /// Returns a builder for an OsslParamArray.
+    ///
+    /// The array is initially empty.
+    #[corresponds(OSSL_PARAM_BLD_new)]
+    #[cfg_attr(any(not(ossl320), osslconf = "OPENSSL_NO_ARGON2"), allow(dead_code))]
+    pub(crate) fn new() -> Result<OsslParamBuilder, ErrorStack> {
+        unsafe {
+            ffi::init();
+
+            cvt_p(ffi::OSSL_PARAM_BLD_new()).map(OsslParamBuilder)
+        }
+    }
+
+    /// Constructs the `OsslParamArray` and clears this builder.
+    #[corresponds(OSSL_PARAM_BLD_to_param)]
+    #[cfg_attr(any(not(ossl320), osslconf = "OPENSSL_NO_ARGON2"), allow(dead_code))]
+    #[allow(clippy::wrong_self_convention)]
+    pub(crate) fn to_param(&mut self) -> Result<OsslParamArray, ErrorStack> {
+        unsafe {
+            let params = cvt_p(ffi::OSSL_PARAM_BLD_to_param(self.0))?;
+            Ok(OsslParamArray::from_ptr(params))
+        }
+    }
+}
+
+impl OsslParamBuilderRef {
+    /// Adds a `BigNum` to `OsslParamBuilder`.
+    ///
+    /// Note, that both key and bn need to exist until the `to_param` is called!
+    #[corresponds(OSSL_PARAM_BLD_push_BN)]
+    #[allow(dead_code)] // TODO: remove when when used by ML-DSA / ML-KEM
+    pub(crate) fn add_bn<'a>(
+        &'a mut self,
+        key: &'a CStr,
+        bn: &'a BigNumRef,
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::OSSL_PARAM_BLD_push_BN(
+                self.as_ptr(),
+                key.as_ptr(),
+                bn.as_ptr(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Adds a utf8 string to `OsslParamBuilder`.
+    ///
+    /// Note, that both `key` and `buf` need to exist until the `to_param` is called!
+    #[corresponds(OSSL_PARAM_BLD_push_utf8_string)]
+    #[allow(dead_code)] // TODO: remove when when used by ML-DSA / ML-KEM
+    pub(crate) fn add_utf8_string<'a>(
+        &'a mut self,
+        key: &'a CStr,
+        buf: &'a str,
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::OSSL_PARAM_BLD_push_utf8_string(
+                self.as_ptr(),
+                key.as_ptr(),
+                buf.as_ptr() as *const c_char,
+                buf.len(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Adds a octet string to `OsslParamBuilder`.
+    ///
+    /// Note, that both `key` and `buf` need to exist until the `to_param` is called!
+    #[corresponds(OSSL_PARAM_BLD_push_octet_string)]
+    #[cfg_attr(any(not(ossl320), osslconf = "OPENSSL_NO_ARGON2"), allow(dead_code))]
+    pub(crate) fn add_octet_string<'a>(
+        &'a mut self,
+        key: &'a CStr,
+        buf: &'a [u8],
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::OSSL_PARAM_BLD_push_octet_string(
+                self.as_ptr(),
+                key.as_ptr(),
+                buf.as_ptr() as *const c_void,
+                buf.len(),
+            ))
+            .map(|_| ())
+        }
+    }
+
+    /// Adds a unsigned int to `OsslParamBuilder`.
+    ///
+    /// Note, that both `key` and `buf` need to exist until the `to_param` is called!
+    #[corresponds(OSSL_PARAM_BLD_push_uint)]
+    #[cfg_attr(any(not(ossl320), osslconf = "OPENSSL_NO_ARGON2"), allow(dead_code))]
+    pub(crate) fn add_uint<'a>(&'a mut self, key: &'a CStr, val: u32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::OSSL_PARAM_BLD_push_uint(
+                self.as_ptr(),
+                key.as_ptr(),
+                val as c_uint,
+            ))
+            .map(|_| ())
+        }
+    }
+}