feat(mitm): implement dynamic linux cert resolution and NSS db injection (#1010)

- Replaced hardcoded LINUX_CERT_DIR with dynamic filesystem probing to support Debian, Arch, Fedora, and openSUSE system trust stores.
- Added updateNssDatabases helper to seamlessly inject root certificates directly into browser NSS databases (e.g., ~/.pki/nssdb, ~/.mozilla/firefox).
- Supported standard and snap-based Chrome/Chromium and Firefox installations.
- Made browser cert injection resilient, executing under the current user to prevent file ownership issues, and safely falling back if certutil is absent.

src/mitm/cert/install.js

@@ -7,7 +7,26 @@ const { log, err } = require("../logger");
 
 const IS_WIN = process.platform === "win32";
 const IS_MAC = process.platform === "darwin";
-const LINUX_CERT_DIR = "/usr/local/share/ca-certificates";
+const LINUX_CERT_PATHS = [
+  // Debian / Ubuntu
+  { dir: "/usr/local/share/ca-certificates", cmd: "update-ca-certificates" },
+  // Arch Linux / CachyOS / Manjaro
+  { dir: "/etc/ca-certificates/trust-source/anchors", cmd: "update-ca-trust" },
+  // Fedora / RHEL / CentOS
+  { dir: "/etc/pki/ca-trust/source/anchors", cmd: "update-ca-trust" },
+  // openSUSE
+  { dir: "/etc/pki/trust/anchors", cmd: "update-ca-certificates" }
+];
+
+function getLinuxCertConfig() {
+  for (const config of LINUX_CERT_PATHS) {
+    if (fs.existsSync(config.dir)) {
+      return config;
+    }
+  }
+  // Fallback to Debian default if none exist
+  return LINUX_CERT_PATHS[0];
+}
 const ROOT_CA_CN = "9Router MITM Root CA";
 
 // Get SHA1 fingerprint from cert file using Node.js crypto
@@ -153,35 +172,93 @@ async function uninstallCertWindows() {
 }
 
 function checkCertInstalledLinux() {
-  const certFile = `${LINUX_CERT_DIR}/9router-root-ca.crt`;
+  const config = getLinuxCertConfig();
+  const certFile = `${config.dir}/9router-root-ca.crt`;
   return Promise.resolve(fs.existsSync(certFile));
 }
 
+async function updateNssDatabases(certPath, action = 'add') {
+  const certName = "9Router MITM Root CA";
+  
+  const script = `
+    if ! command -v certutil &> /dev/null; then
+      exit 0
+    fi
+    
+    DIRS="$HOME/.pki/nssdb $HOME/snap/chromium/current/.pki/nssdb"
+    
+    if [ -d "$HOME/.mozilla/firefox" ]; then
+      for profile in "$HOME"/.mozilla/firefox/*/; do
+        if [ -f "\${profile}cert9.db" ] || [ -f "\${profile}cert8.db" ]; then
+          DIRS="$DIRS $profile"
+        fi
+      done
+    fi
+
+    if [ -d "$HOME/snap/firefox/common/.mozilla/firefox" ]; then
+      for profile in "$HOME"/snap/firefox/common/.mozilla/firefox/*/; do
+        if [ -f "\${profile}cert9.db" ] || [ -f "\${profile}cert8.db" ]; then
+          DIRS="$DIRS $profile"
+        fi
+      done
+    fi
+
+    for db in $DIRS; do
+      if [ -d "$db" ]; then
+        if [ "${action}" = "add" ]; then
+          certutil -d sql:"$db" -A -t "C,," -n "${certName}" -i "${certPath}" 2>/dev/null || \\
+          certutil -d "$db" -A -t "C,," -n "${certName}" -i "${certPath}" 2>/dev/null || true
+        else
+          certutil -d sql:"$db" -D -n "${certName}" 2>/dev/null || \\
+          certutil -d "$db" -D -n "${certName}" 2>/dev/null || true
+        fi
+      fi
+    done
+  `;
+  
+  return new Promise((resolve) => {
+    exec(script, { shell: "/bin/bash" }, () => resolve());
+  });
+}
+
 async function installCertLinux(sudoPassword, certPath) {
   if (!isSudoAvailable()) {
     log(`🔐 Cert: cannot install to system store without sudo — trust this file on clients: ${certPath}`);
+    // Still try to update user NSS DBs even if no sudo!
+    await updateNssDatabases(certPath, 'add');
     return;
   }
-  const destFile = `${LINUX_CERT_DIR}/9router-root-ca.crt`;
-  // Try update-ca-certificates (Debian/Ubuntu), fallback to update-ca-trust (Fedora/RHEL)
-  const cmd = `cp "${certPath}" "${destFile}" && (update-ca-certificates 2>/dev/null || update-ca-trust 2>/dev/null || true)`;
+  
+  const config = getLinuxCertConfig();
+  const destFile = `${config.dir}/9router-root-ca.crt`;
+  
+  // Copy to the discovered directory and execute the specific update command
+  const cmd = `cp "${certPath}" "${destFile}" && (${config.cmd} 2>/dev/null || true)`;
+  
   try {
     await execWithPassword(cmd, sudoPassword);
-    log("🔐 Cert: ✅ installed to Linux trust store");
+    await updateNssDatabases(certPath, 'add');
+    log(`🔐 Cert: ✅ installed to Linux trust store (${config.dir}) and user browser databases`);
   } catch (error) {
-    throw new Error("Certificate install failed");
+    throw new Error(`Certificate install failed: ${error.message}`);
   }
 }
 
 async function uninstallCertLinux(sudoPassword) {
+  // Always try to uninstall from user DBs even without sudo
+  await updateNssDatabases(null, 'delete');
+
   if (!isSudoAvailable()) {
     return;
   }
-  const destFile = `${LINUX_CERT_DIR}/9router-root-ca.crt`;
-  const cmd = `rm -f "${destFile}" && (update-ca-certificates 2>/dev/null || update-ca-trust 2>/dev/null || true)`;
+  
+  const config = getLinuxCertConfig();
+  const destFile = `${config.dir}/9router-root-ca.crt`;
+  const cmd = `rm -f "${destFile}" && (${config.cmd} 2>/dev/null || true)`;
+  
   try {
     await execWithPassword(cmd, sudoPassword);
-    log("🔐 Cert: ✅ uninstalled from Linux trust store");
+    log("🔐 Cert: ✅ uninstalled from Linux trust store and user browser databases");
   } catch (error) {
     throw new Error("Failed to uninstall certificate");
   }