Populate the GELI passphrase cache with the kern.geom.eli.passphrase

variable (if any) provided in the boot environment.  Unset it from
the kernel environment after doing this, so that the passphrase is
no longer present in kernel memory once we enter userland.

This will make it possible to provide a GELI passphrase via the boot
loader; FreeBSD's loader does not yet do this, but GRUB (and PCBSD)
will have support for this soon.

Tested by:	kmoore

1 files changed, 19 insertions, 0 deletions

diff --git a/sys/geom/eli/g_eli.c b/sys/geom/eli/g_eli.c
index f545b75..23fd7ba 100644
--- a/sys/geom/eli/g_eli.c
+++ b/sys/geom/eli/g_eli.c
@@ -93,6 +93,25 @@ SYSCTL_UINT(_kern_geom_eli, OID_AUTO, boot_passcache, CTLFLAG_RD,
     &g_eli_boot_passcache, 0,
     "Passphrases are cached during boot process for possible reuse");
 static void
+fetch_loader_passphrase(void * dummy)
+{
+	char * env_passphrase;
+
+	KASSERT(dynamic_kenv, ("need dynamic kenv"));
+
+	if ((env_passphrase = kern_getenv("kern.geom.eli.passphrase")) != NULL) {
+		/* Extract passphrase from the environment. */
+		strlcpy(cached_passphrase, env_passphrase,
+		    sizeof(cached_passphrase));
+		freeenv(env_passphrase);
+
+		/* Wipe the passphrase from the environment. */
+		kern_unsetenv("kern.geom.eli.passphrase");
+	}
+}
+SYSINIT(geli_fetch_loader_passphrase, SI_SUB_KMEM + 1, SI_ORDER_ANY,
+    fetch_loader_passphrase, NULL);
+static void
 zero_boot_passcache(void * dummy)
 {