Am 22.12.21 um 14:52 schrieb Fabian Grünbichler:
in case we have no explicit fingerprint, we use openssl's regular "PEER"
verification. if we have a fingerprint, we ignore openssl altogether and
just verify the fingerprint of the presented leaf certificate.
Signed-off-by: Fabian Grünbichler <f.gruenbich...@proxmox.com>
---
Notes:
v3: switch to using hex instead of no-longer-existing digest_to_hex
v2: new
src/main.rs | 47 ++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 3 deletions(-)
diff --git a/src/main.rs b/src/main.rs
index 582214c..49d6ffe 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -134,9 +134,50 @@ impl CtrlTunnel {
}
let mut ssl_connector_builder = SslConnector::builder(SslMethod::tls())?;
- if fingerprint.is_some() {
- // FIXME actually verify fingerprint via callback!
-
ssl_connector_builder.set_verify(openssl::ssl::SslVerifyMode::NONE);
+ if let Some(expected) = fingerprint {
+ ssl_connector_builder.set_verify_callback(
+ openssl::ssl::SslVerifyMode::NONE,
+ move |_valid, ctx| {
+ let cert = match ctx.current_cert() {
+ Some(cert) => cert,
+ None => {
+ eprintln!("SSL context lacks current
certificate.");
+ return false;
+ }
+ };
+
+ let depth = ctx.error_depth();
+ if depth != 0 {
+ return true;
+ }
Sorry about my ignorance. Does using SslVerifyMode::NONE imply that
there is an error? At depth 0? Why is it fine to return true if not?
+
+ let fp = match
cert.digest(openssl::hash::MessageDigest::sha256()) {
+ Ok(fp) => fp,
+ Err(err) => {
+ // should not happen
+ eprintln!("failed to calculate certificate FP -
{}", err);
+ return false;
+ }
+ };
+ let fp_string = hex::encode(&fp);
+ let fp_string = fp_string
+ .as_bytes()
+ .chunks(2)
+ .map(|v| std::str::from_utf8(v).unwrap())
+ .collect::<Vec<&str>>()
+ .join(":");
+
+ let expected = expected.to_lowercase();
+ if expected == fp_string {
+ true
+ } else {
+ eprintln!("certificate fingerprint does not match expected
fingerprint!");
+ eprintln!("expected: {}", expected);
+ eprintln!("encountered: {}", fp_string);
+ false
+ }
+ },
+ );
} else {
ssl_connector_builder.set_verify(openssl::ssl::SslVerifyMode::PEER);
}
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