4 files changed, 17 insertions, 0 deletions
diff --git a/src/download-via-ssh/download-via-ssh.cc b/src/download-via-ssh/download-via-ssh.cc
index 0fa089724d7f..466233c7a5e5 100644
--- a/src/download-via-ssh/download-via-ssh.cc
+++ b/src/download-via-ssh/download-via-ssh.cc
@@ -101,6 +101,11 @@ void run(Strings args)
 
     std::cout << std::endl;
 
+    /* Pass on the location of the daemon client's SSH authentication
+       socket. */
+    string sshAuthSock = settings.get("ssh-auth-sock");
+    if (sshAuthSock != "") setenv("SSH_AUTH_SOCK", sshAuthSock.c_str(), 1);
+
     string host = settings.sshSubstituterHosts.front();
     std::pair<FdSink, FdSource> pipes = connect(host);
 
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 82f3e952a0b5..e9fe0beca4ef 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -122,6 +122,14 @@ void Settings::set(const string & name, const string & value)
 }
 
 
+string Settings::get(const string & name, const string & def)
+{
+    auto i = settings.find(name);
+    if (i == settings.end()) return def;
+    return i->second;
+}
+
+
 void Settings::update()
 {
     get(tryFallback, "build-fallback");
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index f1748336fdac..d16969c9e010 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -21,6 +21,8 @@ struct Settings {
 
     void set(const string & name, const string & value);
 
+    string get(const string & name, const string & def = "");
+
     void update();
 
     string pack();
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index b3967bb2418f..7c51f395aae2 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -163,6 +163,8 @@ void RemoteStore::setOptions()
 
     if (GET_PROTOCOL_MINOR(daemonVersion) >= 12) {
         Settings::SettingsMap overrides = settings.getOverrides();
+        if (overrides["ssh-auth-sock"] == "")
+            overrides["ssh-auth-sock"] = getEnv("SSH_AUTH_SOCK");
         writeInt(overrides.size(), to);
         foreach (Settings::SettingsMap::iterator, i, overrides) {
             writeString(i->first, to);