Add fips-3678 feature (#52)

* Add rerun-if-env-changed instructions for BORING_* variables

* Use X509_get0_notBefore() and X509_get0_notAfter() instead of X509_getm_notBefore() and X509_getm_notAfter().

According to
https://www.openssl.org/docs/man1.1.0/man3/X509_getm_notBefore.html,
"X509_getm_notBefore() and X509_getm_notAfter() are similar to
X509_get0_notBefore() and X509_get0_notAfter() except they return
non-constant mutable references to the associated date field of the
certificate".

* Only update boringssl submodule if BORING_BSSL_PATH not provided

* Allow BORING_BSSL_LIB_PATH to control link search

* Add fips feature

* Use X509_set_notAfter unconditionally for FIPS compatibility

This is equivalent according to
https://boringssl.googlesource.com/boringssl/+/c947efabcbc38dcf93e8ad0e6a76206cf0ec8072

The version of boringssl that's FIPS-certified doesn't have `X509_set1_notAfter`.
The only difference between that and `X509_set_notAfter` is whether they're const-correct,
which doesn't seem worth having two different code-paths.

* Check out fips commit automatically

* Verify the version of the compiler used for building boringssl

NIST specifies that it needs to be 7.0.1; I originally tried building with clang 10 and it failed.
Theoretically this should check the versions of Go and Ninja too, but they haven't given me trouble in practice.

Example error:
```
   Compiling boring-sys v1.1.1 (/home/jnelson/work/boring/boring-sys)
error: failed to run custom build command for `boring-sys v1.1.1 (/home/jnelson/work/boring/boring-sys)`

Caused by:
  process didn't exit successfully: `/home/jnelson/work/boring/target/debug/build/boring-sys-31b8ce53031cfd83/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=BORING_BSSL_PATH

  --- stderr
  warning: missing clang-7, trying other compilers: Permission denied (os error 13)
  warning: FIPS requires clang version 7.0.1, skipping incompatible version "clang version 10.0.0-4ubuntu1 "
  thread 'main' panicked at 'unsupported clang version "cc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0": FIPS requires clang 7.0.1', boring-sys/build.rs:216:13
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

* Add Github actions workflow testing FIPS

Co-authored-by: Joshua Nelson <[email protected]>

Author: behrat

.github/workflows/ci.yml

@@ -159,3 +159,18 @@ jobs:
     - if: "!startsWith(matrix.os, 'windows')"
       run: cargo test
       name: Run tests (not Windows)
+
+  test-fips:
+    name: Test FIPS integration
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: 'recursive'
+    - name: Install Rust (rustup)
+      run: rustup update stable --no-self-update && rustup default stable
+      shell: bash
+    - name: Install Clang-7
+      run: sudo apt-get install -y clang-7
+    - run: cargo test --features fips
+      name: Run tests

.gitmodules

@@ -1,4 +1,7 @@
 [submodule "boring-sys/deps/boringssl"]
 	path = boring-sys/deps/boringssl
 	url = https://github.com/google/boringssl.git
-	ignore = dirty
+	ignore = dirty
+[submodule "boring-sys/deps/boringssl-fips"]
+	path = boring-sys/deps/boringssl-fips
+	url = https://github.com/google/boringssl.git

README.md

@@ -22,6 +22,18 @@ _Notes_: The crate will look for headers in the `$BORING_BSSL_INCLUDE_PATH/opens
 
 _Warning_: When providing a different version of BoringSSL make sure to use a compatible one, the crate relies on the presence of certain functions.
 
+## Building with a FIPS-validated module
+
+Only BoringCrypto module version ae223d6138807a13006342edfeef32e813246b39, as
+certified with [certificate
+3678](https://csrc.nist.gov/projects/cryptographic-module-validation-program/certificate/3678)
+is supported by this crate. Support is enabled by this crate's `fips` feature.
+
+`boring-sys` comes with a test that FIPS is enabled/disabled depending on the feature flag. You can run it as follows:
+```bash
+$ cargo test --features fips fips::is_enabled
+```
+
 ## Contribution
 
 Unless you explicitly state otherwise, any contribution intentionally

boring-sys/Cargo.toml

@@ -29,3 +29,7 @@ include = [
 [build-dependencies]
 bindgen = { version = "0.59", default-features = false, features = ["runtime"] }
 cmake = "0.1"
+
+[features]
+# Use a FIPS-validated version of boringssl.
+fips = []

boring-sys/build.rs

@@ -1,3 +1,6 @@
+use std::path::{Path, PathBuf};
+use std::process::Command;
+
 // NOTE: this build script is adopted from quiche (https://github.com/cloudflare/quiche)
 
 // Additional parameters for Android build of BoringSSL.
@@ -85,6 +88,11 @@ fn get_boringssl_platform_output_path() -> String {
     }
 }
 
+#[cfg(feature = "fips")]
+const BORING_SSL_PATH: &str = "deps/boringssl-fips";
+#[cfg(not(feature = "fips"))]
+const BORING_SSL_PATH: &str = "deps/boringssl";
+
 /// Returns a new cmake::Config for building BoringSSL.
 ///
 /// It will add platform-specific parameters if needed.
@@ -93,7 +101,7 @@ fn get_boringssl_cmake_config() -> cmake::Config {
     let os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
     let pwd = std::env::current_dir().unwrap();
 
-    let mut boringssl_cmake = cmake::Config::new("deps/boringssl");
+    let mut boringssl_cmake = cmake::Config::new(BORING_SSL_PATH);
 
     // Add platform-specific parameters.
     match os.as_ref() {
@@ -105,6 +113,7 @@ fn get_boringssl_cmake_config() -> cmake::Config {
             };
 
             // We need ANDROID_NDK_HOME to be set properly.
+            println!("cargo:rerun-if-env-changed=ANDROID_NDK_HOME");
             let android_ndk_home = std::env::var("ANDROID_NDK_HOME")
                 .expect("Please set ANDROID_NDK_HOME for Android build");
             let android_ndk_home = std::path::Path::new(&android_ndk_home);
@@ -161,7 +170,8 @@ fn get_boringssl_cmake_config() -> cmake::Config {
             if arch == "x86" && os != "windows" {
                 boringssl_cmake.define(
                     "CMAKE_TOOLCHAIN_FILE",
-                    pwd.join("deps/boringssl/src/util/32-bit-toolchain.cmake")
+                    pwd.join(BORING_SSL_PATH)
+                        .join("src/util/32-bit-toolchain.cmake")
                         .as_os_str(),
                 );
             }
@@ -171,42 +181,107 @@ fn get_boringssl_cmake_config() -> cmake::Config {
     }
 }
 
-fn main() {
-    use std::env;
-    use std::path::{Path, PathBuf};
-    use std::process::Command;
-
-    if !Path::new("deps/boringssl/CMakeLists.txt").exists() {
-        println!("cargo:warning=fetching boringssl git submodule");
-        // fetch the boringssl submodule
-        let status = Command::new("git")
-            .args(&[
-                "submodule",
-                "update",
-                "--init",
-                "--recursive",
-                "deps/boringssl",
-            ])
-            .status();
-        if !status.map_or(false, |status| status.success()) {
-            panic!("failed to fetch submodule - consider running `git submodule update --init --recursive deps/boringssl` yourself");
+/// Verify that the toolchains match https://csrc.nist.gov/CSRC/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp3678.pdf
+/// See "Installation Instructions" under section 12.1.
+// TODO: maybe this should also verify the Go and Ninja versions? But those haven't been an issue in practice ...
+fn verify_fips_clang_version() -> (&'static str, &'static str) {
+    fn version(tool: &str) -> String {
+        let output = match Command::new(tool).arg("--version").output() {
+            Ok(o) => o,
+            Err(e) => {
+                eprintln!("warning: missing {}, trying other compilers: {}", tool, e);
+                // NOTE: hard-codes that the loop below checks the version
+                return String::new();
+            }
+        };
+        assert!(output.status.success());
+        let output = std::str::from_utf8(&output.stdout).expect("invalid utf8 output");
+        output.lines().next().expect("empty output").to_string()
+    }
+
+    const REQUIRED_CLANG_VERSION: &str = "7.0.1";
+    for (cc, cxx) in [
+        ("clang-7", "clang++-7"),
+        ("clang", "clang++"),
+        ("cc", "c++"),
+    ] {
+        let cc_version = version(cc);
+        if cc_version.contains(REQUIRED_CLANG_VERSION) {
+            assert!(
+                version(cxx).contains(REQUIRED_CLANG_VERSION),
+                "mismatched versions of cc and c++"
+            );
+            return (cc, cxx);
+        } else if cc == "cc" {
+            panic!(
+                "unsupported clang version \"{}\": FIPS requires clang {}",
+                cc_version, REQUIRED_CLANG_VERSION
+            );
+        } else if !cc_version.is_empty() {
+            eprintln!(
+                "warning: FIPS requires clang version {}, skipping incompatible version \"{}\"",
+                REQUIRED_CLANG_VERSION, cc_version
+            );
         }
     }
+    unreachable!()
+}
+
+fn main() {
+    use std::env;
 
+    println!("cargo:rerun-if-env-changed=BORING_BSSL_PATH");
     let bssl_dir = std::env::var("BORING_BSSL_PATH").unwrap_or_else(|_| {
+        if !Path::new(BORING_SSL_PATH).join("CMakeLists.txt").exists() {
+            println!("cargo:warning=fetching boringssl git submodule");
+            // fetch the boringssl submodule
+            let status = Command::new("git")
+                .args(&[
+                    "submodule",
+                    "update",
+                    "--init",
+                    "--recursive",
+                    BORING_SSL_PATH,
+                ])
+                .status();
+            if !status.map_or(false, |status| status.success()) {
+                panic!("failed to fetch submodule - consider running `git submodule update --init --recursive deps/boringssl` yourself");
+            }
+        }
+
         let mut cfg = get_boringssl_cmake_config();
 
         if cfg!(feature = "fuzzing") {
             cfg.cxxflag("-DBORINGSSL_UNSAFE_DETERMINISTIC_MODE")
                 .cxxflag("-DBORINGSSL_UNSAFE_FUZZER_MODE");
         }
+        if cfg!(feature = "fips") {
+            let (clang, clangxx) = verify_fips_clang_version();
+            cfg.define("CMAKE_C_COMPILER", clang);
+            cfg.define("CMAKE_CXX_COMPILER", clangxx);
+            cfg.define("CMAKE_ASM_COMPILER", clang);
+            cfg.define("FIPS", "1");
+        }
 
         cfg.build_target("bssl").build().display().to_string()
     });
 
     let build_path = get_boringssl_platform_output_path();
-    let build_dir = format!("{}/build/{}", bssl_dir, build_path);
-    println!("cargo:rustc-link-search=native={}", build_dir);
+    if cfg!(feature = "fips") {
+        println!(
+            "cargo:rustc-link-search=native={}/build/crypto/{}",
+            bssl_dir, build_path
+        );
+        println!(
+            "cargo:rustc-link-search=native={}/build/ssl/{}",
+            bssl_dir, build_path
+        );
+    } else {
+        println!(
+            "cargo:rustc-link-search=native={}/build/{}",
+            bssl_dir, build_path
+        );
+    }
 
     println!("cargo:rustc-link-lib=static=crypto");
     println!("cargo:rustc-link-lib=static=ssl");
@@ -216,10 +291,14 @@ fn main() {
         println!("cargo:rustc-cdylib-link-arg=-Wl,-undefined,dynamic_lookup");
     }
 
-    let include_path = PathBuf::from(
-        std::env::var("BORING_BSSL_INCLUDE_PATH")
-            .unwrap_or_else(|_| String::from("deps/boringssl/src/include")),
-    );
+    println!("cargo:rerun-if-env-changed=BORING_BSSL_INCLUDE_PATH");
+    let include_path = std::env::var("BORING_BSSL_INCLUDE_PATH").unwrap_or_else(|_| {
+        if cfg!(feature = "fips") {
+            format!("{}/include", BORING_SSL_PATH)
+        } else {
+            format!("{}/src/include", BORING_SSL_PATH)
+        }
+    });
 
     let mut builder = bindgen::Builder::default()
         .derive_copy(true)
@@ -234,12 +313,13 @@ fn main() {
         .layout_tests(true)
         .prepend_enum_name(true)
         .rustfmt_bindings(true)
-        .clang_args(&["-I", include_path.to_str().unwrap()]);
+        .clang_args(&["-I", &include_path]);
 
     let headers = [
         "aes.h",
         "asn1_mac.h",
         "asn1t.h",
+        #[cfg(not(feature = "fips"))]
         "blake2.h",
         "blowfish.h",
         "cast.h",
@@ -264,11 +344,18 @@ fn main() {
         "ripemd.h",
         "siphash.h",
         "srtp.h",
+        #[cfg(not(feature = "fips"))]
         "trust_token.h",
         "x509v3.h",
     ];
     for header in &headers {
-        builder = builder.header(include_path.join("openssl").join(header).to_str().unwrap());
+        builder = builder.header(
+            Path::new(&include_path)
+                .join("openssl")
+                .join(header)
+                .to_str()
+                .unwrap(),
+        );
     }
 
     let bindings = builder.generate().expect("Unable to generate bindings");

boring-sys/deps/boringssl-fips

@@ -21,3 +21,7 @@ boring-sys = { version = ">=1.1.0,<3.0.0", path = "../boring-sys" }
 [dev-dependencies]
 hex = "0.4"
 rusty-hook = "^0.11"
+
+[features]
+# Use a FIPS-validated version of boringssl.
+fips = ["boring-sys/fips"]

boring/Cargo.toml

@@ -0,0 +1,3 @@
+fn main() {
+    println!("boring::fips::enabled(): {}", boring::fips::enabled());
+}

boring/examples/fips_enabled.rs

@@ -81,6 +81,7 @@ fn mk_request(privkey: &PKey<Private>) -> Result<X509Req, ErrorStack> {
 }
 
 /// Make a certificate and private key signed by the given CA cert and private key
+#[cfg_attr(feature = "fips", allow(unreachable_code, unused_variables))]
 fn mk_ca_signed_cert(
     ca_cert: &X509Ref,
     ca_privkey: &PKeyRef<Private>,
@@ -98,7 +99,15 @@ fn mk_ca_signed_cert(
         serial.to_asn1_integer()?
     };
     cert_builder.set_serial_number(&serial_number)?;
+
+    #[cfg(not(feature = "fips"))]
     cert_builder.set_subject_name(req.subject_name())?;
+    #[cfg(feature = "fips")]
+    {
+        eprintln!("mk_certs not supported with FIPS module");
+        std::process::exit(1);
+    }
+
     cert_builder.set_issuer_name(ca_cert.subject_name())?;
     cert_builder.set_pubkey(&privkey)?;
     let not_before = Asn1Time::days_from_now(0)?;

boring/examples/mk_certs.rs

@@ -20,3 +20,11 @@ pub fn enable(enabled: bool) -> Result<(), ErrorStack> {
 pub fn enabled() -> bool {
     unsafe { ffi::FIPS_mode() != 0 }
 }
+
+#[test]
+fn is_enabled() {
+    #[cfg(feature = "fips")]
+    assert!(enabled());
+    #[cfg(not(feature = "fips"))]
+    assert!(!enabled());
+}