[client] Profile ownership console user tofu (#7529)

* Add consoleuser and stamp default profile on known username in migration

* Refactor consoleuser to verify Id, fix seats on linux and default stamp

* Add default profile claim

* Add disable auto-claim of default profile and always fail close

* Add disable auto-claim flag to migration

* Adding timeout to console user on Linux and close library load on darwin

* Fixed failed close test

* Close both Dlopen for darwin

* Replace RegisterFunc with purego.Dlsym to avoid possible panic

* Fix freebsd tty enumeration

* Fix active profile migration logic and add test

* Log defaultClaimDisabled error once

* Guard against panicking console user lookup.

* Fix merge conflict

* Fix broken tests

client/internal/ipcauth/consoleuser.go

@@ -0,0 +1,43 @@
+package ipcauth
+
+import (
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// logConsolePanic keeps the notice to once per process.
+var logConsolePanic sync.Once
+
+// IsConsoleUser reports whether a caller is sitting at one of this machine's
+// consoles right now.
+//
+// It is false on a headless machine, which has no seat to sit at, on a
+// platform that exposes no console-user lookup at all, and whenever the lookup
+// fails. Callers must read that as "cannot confirm" rather than as proof of
+// absence. It gates handing out ownership, so a lookup that cannot answer
+// withholds a claim, and never grants one.
+func IsConsoleUser(id Identity) bool {
+	if !id.Known() {
+		return false
+	}
+
+	return guardConsoleLookup(id, isConsoleUser)
+}
+
+// guardConsoleLookup runs a platform lookup and turns a panic out of it into
+// "cannot confirm".
+func guardConsoleLookup(id Identity, lookup func(Identity) bool) (atConsole bool) {
+	defer func() {
+		r := recover()
+		if r == nil {
+			return
+		}
+		atConsole = false
+		logConsolePanic.Do(func() {
+			log.Errorf("console user lookup panicked, no caller will be treated as being at the console: %v", r)
+		})
+	}()
+
+	return lookup(id)
+}