Resolve an injection vulnerability in EKU creation

boring/src/asn1.rs

@@ -38,6 +38,7 @@ use crate::bio::MemBio;
 use crate::bn::{BigNum, BigNumRef};
 use crate::error::ErrorStack;
 use crate::nid::Nid;
+use crate::stack::Stackable;
 use crate::string::OpensslString;
 use crate::{cvt, cvt_p};
 
@@ -555,6 +556,10 @@ foreign_type_and_impl_send_sync! {
     pub struct Asn1Object;
 }
 
+impl Stackable for Asn1Object {
+    type StackType = ffi::stack_st_ASN1_OBJECT;
+}
+
 impl Asn1Object {
     /// Constructs an ASN.1 Object Identifier from a string representation of
     /// the OID.

boring/src/x509/extension.rs

@@ -17,9 +17,10 @@
 //! ```
 use std::fmt::Write;
 
+use crate::asn1::Asn1Object;
 use crate::error::ErrorStack;
 use crate::nid::Nid;
-use crate::x509::{Asn1Object, GeneralName, Stack, X509Extension, X509v3Context};
+use crate::x509::{GeneralName, Stack, X509Extension, X509v3Context};
 use foreign_types::ForeignType;
 
 /// An extension which indicates whether a certificate is a CA certificate.
@@ -222,18 +223,7 @@ impl KeyUsage {
 /// for which the certificate public key can be used for.
 pub struct ExtendedKeyUsage {
     critical: bool,
-    server_auth: bool,
-    client_auth: bool,
-    code_signing: bool,
-    email_protection: bool,
-    time_stamping: bool,
-    ms_code_ind: bool,
-    ms_code_com: bool,
-    ms_ctl_sign: bool,
-    ms_sgc: bool,
-    ms_efs: bool,
-    ns_sgc: bool,
-    other: Vec<String>,
+    items: Vec<String>,
 }
 
 impl Default for ExtendedKeyUsage {
@@ -247,18 +237,7 @@ impl ExtendedKeyUsage {
     pub fn new() -> ExtendedKeyUsage {
         ExtendedKeyUsage {
             critical: false,
-            server_auth: false,
-            client_auth: false,
-            code_signing: false,
-            email_protection: false,
-            time_stamping: false,
-            ms_code_ind: false,
-            ms_code_com: false,
-            ms_ctl_sign: false,
-            ms_sgc: false,
-            ms_efs: false,
-            ns_sgc: false,
-            other: vec![],
+            items: vec![],
         }
     }
 
@@ -270,95 +249,69 @@ impl ExtendedKeyUsage {
 
     /// Sets the `serverAuth` flag to `true`.
     pub fn server_auth(&mut self) -> &mut ExtendedKeyUsage {
-        self.server_auth = true;
-        self
+        self.other("serverAuth")
     }
 
     /// Sets the `clientAuth` flag to `true`.
     pub fn client_auth(&mut self) -> &mut ExtendedKeyUsage {
-        self.client_auth = true;
-        self
+        self.other("clientAuth")
     }
 
     /// Sets the `codeSigning` flag to `true`.
     pub fn code_signing(&mut self) -> &mut ExtendedKeyUsage {
-        self.code_signing = true;
-        self
+        self.other("codeSigning")
     }
 
     /// Sets the `timeStamping` flag to `true`.
     pub fn time_stamping(&mut self) -> &mut ExtendedKeyUsage {
-        self.time_stamping = true;
-        self
+        self.other("timeStamping")
     }
 
     /// Sets the `msCodeInd` flag to `true`.
     pub fn ms_code_ind(&mut self) -> &mut ExtendedKeyUsage {
-        self.ms_code_ind = true;
-        self
+        self.other("msCodeInd")
     }
 
     /// Sets the `msCodeCom` flag to `true`.
     pub fn ms_code_com(&mut self) -> &mut ExtendedKeyUsage {
-        self.ms_code_com = true;
-        self
+        self.other("msCodeCom")
     }
 
     /// Sets the `msCTLSign` flag to `true`.
     pub fn ms_ctl_sign(&mut self) -> &mut ExtendedKeyUsage {
-        self.ms_ctl_sign = true;
-        self
+        self.other("msCTLSign")
     }
 
     /// Sets the `msSGC` flag to `true`.
     pub fn ms_sgc(&mut self) -> &mut ExtendedKeyUsage {
-        self.ms_sgc = true;
-        self
+        self.other("msSGC")
     }
 
     /// Sets the `msEFS` flag to `true`.
     pub fn ms_efs(&mut self) -> &mut ExtendedKeyUsage {
-        self.ms_efs = true;
-        self
+        self.other("msEFS")
     }
 
     /// Sets the `nsSGC` flag to `true`.
     pub fn ns_sgc(&mut self) -> &mut ExtendedKeyUsage {
-        self.ns_sgc = true;
-        self
+        self.other("nsSGC")
     }
 
     /// Sets a flag not already defined.
     pub fn other(&mut self, other: &str) -> &mut ExtendedKeyUsage {
-        self.other.push(other.to_owned());
+        self.items.push(other.to_string());
         self
     }
 
     /// Return the `ExtendedKeyUsage` extension as an `X509Extension`.
     pub fn build(&self) -> Result<X509Extension, ErrorStack> {
-        let mut value = String::new();
-        let mut first = true;
-        append(&mut value, &mut first, self.critical, "critical");
-        append(&mut value, &mut first, self.server_auth, "serverAuth");
-        append(&mut value, &mut first, self.client_auth, "clientAuth");
-        append(&mut value, &mut first, self.code_signing, "codeSigning");
-        append(
-            &mut value,
-            &mut first,
-            self.email_protection,
-            "emailProtection",
-        );
-        append(&mut value, &mut first, self.time_stamping, "timeStamping");
-        append(&mut value, &mut first, self.ms_code_ind, "msCodeInd");
-        append(&mut value, &mut first, self.ms_code_com, "msCodeCom");
-        append(&mut value, &mut first, self.ms_ctl_sign, "msCTLSign");
-        append(&mut value, &mut first, self.ms_sgc, "msSGC");
-        append(&mut value, &mut first, self.ms_efs, "msEFS");
-        append(&mut value, &mut first, self.ns_sgc, "nsSGC");
-        for other in &self.other {
-            append(&mut value, &mut first, true, other);
+        let mut stack = Stack::new()?;
+        for item in &self.items {
+            stack.push(Asn1Object::from_str(item)?)?;
+        }
+        unsafe {
+            X509Extension::new_internal(Nid::EXT_KEY_USAGE, self.critical, stack.as_ptr().cast())
         }
-        X509Extension::new_nid(None, None, Nid::EXT_KEY_USAGE, &value)
     }
 }
 

boring/src/x509/tests.rs

@@ -288,6 +288,14 @@ fn x509_extension_to_der() {
     }
 }
 
+#[test]
+fn eku_invalid_other() {
+    assert!(ExtendedKeyUsage::new()
+        .other("1.1.1.1.1,2.2.2.2.2")
+        .build()
+        .is_err());
+}
+
 #[test]
 fn x509_req_builder() {
     let pkey = pkey();