Merge pull request #8 from str4d/getrandom

Replace RAND_bytes with getrandom crate

Cargo.toml

@@ -17,6 +17,7 @@ categories = ["api-bindings", "cryptography", "hardware-support"]
 keywords   = ["ccid", "ecdsa", "rsa", "piv", "yubikey"]
 
 [dependencies]
+getrandom = "0.1"
 libc = "0.2"
 log = "0.4"
 zeroize = "1"

src/internal.rs

@@ -69,7 +69,6 @@ extern "C" {
         keylen: i32,
         out: *mut u8,
     ) -> i32;
-    fn RAND_bytes(buf: *mut u8, num: i32) -> i32;
 }
 
 /// DES-related errors
@@ -234,26 +233,6 @@ pub unsafe fn yk_des_is_weak_key(key: *const u8, _cb_key: usize) -> bool {
     DES_is_weak_key(key as (*mut [u8; 8])) != 0
 }
 
-/// PRNG errors/results
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-#[repr(i32)]
-pub enum PRngErrorKind {
-    /// Ok
-    Ok = 0,
-
-    /// General error
-    GeneralError = -1,
-}
-
-/// Generate bytes with the PRNG
-pub unsafe fn _ykpiv_prng_generate(buffer: *mut u8, cb_req: usize) -> PRngErrorKind {
-    if RAND_bytes(buffer, cb_req as (i32)) != -1 {
-        PRngErrorKind::Ok
-    } else {
-        PRngErrorKind::GeneralError
-    }
-}
-
 /// PKCS#5 error types
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[repr(i32)]

src/util.rs

@@ -34,8 +34,10 @@
 #![allow(clippy::missing_safety_doc, clippy::too_many_arguments)]
 
 use crate::{consts::*, error::ErrorKind, internal::*, yubikey::*};
+use getrandom::getrandom;
 use libc::{calloc, free, memcpy, memmove, realloc, time};
 use log::{error, warn};
+use std::ops::DerefMut;
 use std::{ffi::CString, mem, os::raw::c_void, ptr};
 use zeroize::{Zeroize, Zeroizing};
 
@@ -125,9 +127,7 @@ pub unsafe fn ykpiv_util_set_cardid(
     let mut res = Ok(());
 
     if cardid.is_null() {
-        if _ykpiv_prng_generate(id.as_mut_ptr(), id.len()) != PRngErrorKind::Ok {
-            return Err(ErrorKind::RandomnessError);
-        }
+        getrandom(&mut id).map_err(|_| ErrorKind::RandomnessError)?;
     } else {
         memcpy(
             id.as_mut_ptr() as (*mut c_void),
@@ -215,9 +215,7 @@ pub unsafe fn ykpiv_util_set_cccid(
     let len: usize;
 
     if ccc.is_null() {
-        if _ykpiv_prng_generate(id.as_mut_ptr(), id.len()) != PRngErrorKind::Ok {
-            return Err(ErrorKind::RandomnessError);
-        }
+        getrandom(&mut id).map_err(|_| ErrorKind::RandomnessError)?;
     } else {
         memcpy(
             id.as_mut_ptr() as (*mut c_void),
@@ -1593,7 +1591,6 @@ pub unsafe fn ykpiv_util_set_protected_mgm(
     state: &mut YubiKey,
     mgm: *mut YkPivMgm,
 ) -> Result<(), ErrorKind> {
-    let mut prngrc: PRngErrorKind;
     let mut f_generate: bool;
     let mut mgm_key = Zeroizing::new([0u8; 24]);
     // TODO(tarcieri): replace vec with wrapper type that impls `Zeroize`
@@ -1632,9 +1629,8 @@ pub unsafe fn ykpiv_util_set_protected_mgm(
     loop {
         if f_generate {
             // generate a new mgm key
-            prngrc = _ykpiv_prng_generate(mgm_key.as_mut_ptr(), mgm_key.len());
-            if prngrc != PRngErrorKind::Ok {
-                error!("could not generate new mgm, err = {:?}", prngrc);
+            if let Err(e) = getrandom(mgm_key.deref_mut()) {
+                error!("could not generate new mgm, err = {}", e);
                 let _ = _ykpiv_end_transaction(state);
                 return Err(ErrorKind::RandomnessError);
             }

src/yubikey.rs

@@ -39,9 +39,10 @@ use crate::{
     error::ErrorKind,
     internal::{
         des_decrypt, des_destroy_key, des_encrypt, des_import_key, yk_des_is_weak_key,
-        DesErrorKind, DesKey, PRngErrorKind, _ykpiv_prng_generate,
+        DesErrorKind, DesKey,
     },
 };
+use getrandom::getrandom;
 use libc::{c_char, free, malloc, memcmp, memcpy, memmove, memset, strlen, strncasecmp};
 use log::{error, info, trace, warn};
 use std::{convert::TryInto, ffi::CStr, mem, os::raw::c_void, ptr, slice};
@@ -851,26 +852,18 @@ pub unsafe fn ykpiv_authenticate(state: &mut YubiKey, mut key: *const u8) -> Res
         apdu.data[1] = 20; // 2 + 8 + 2 +8
         apdu.data[2] = 0x80;
         apdu.data[3] = 8;
-        memcpy(
-            apdu.data[4..12].as_mut_ptr() as *mut c_void,
-            response.as_ptr() as *const c_void,
-            8,
-        );
+        apdu.data[4..12].copy_from_slice(&response);
         apdu.data[12] = 0x81;
         apdu.data[13] = 8;
 
-        if _ykpiv_prng_generate(data[14..20].as_mut_ptr(), 8) == PRngErrorKind::GeneralError {
+        if getrandom(&mut data[14..22]).is_err() {
             error!("failed getting randomness for authentication.");
             let _ = _ykpiv_end_transaction(state);
             return Err(ErrorKind::RandomnessError);
         }
+        challenge.copy_from_slice(&data[14..22]);
 
-        memcpy(
-            challenge.as_mut_ptr() as *mut c_void,
-            data[14..20].as_ptr() as *const c_void,
-            8,
-        );
-        apdu.lc = 20;
+        apdu.lc = 22;
 
         res = _send_data(state, &mut apdu, data.as_mut_ptr(), &mut recv_len, &mut sw);