Add support for creating GELI devices with older metadata version for use

with older FreeBSD versions:
- Add -V option to 'geli init' to specify version number. If no -V is given
  the most recent version is used.
- If -V is given don't allow to use features not supported by this version.
- Print version in 'geli list' output.
- Update manual page and add table describing which GELI version is
  supported by which FreeBSD version, so one can use it when preparing GELI
  device for older FreeBSD version.

Inspired by:	Garrett Cooper <yanegomi@gmail.com>
MFC after:	3 days

2 files changed, 56 insertions, 5 deletions

diff --git a/sys/geom/eli/g_eli.c b/sys/geom/eli/g_eli.c
index fce52ae..b5e4f7b 100644
--- a/sys/geom/eli/g_eli.c
+++ b/sys/geom/eli/g_eli.c
@@ -713,6 +713,7 @@ g_eli_create(struct gctl_req *req, struct g_class *mp, struct g_provider *bpp,
 	else
 		gp->access = g_std_access;
 
+	sc->sc_version = md->md_version;
 	sc->sc_inflight = 0;
 	sc->sc_crypto = G_ELI_CRYPTO_UNKNOWN;
 	sc->sc_flags = md->md_flags;
@@ -1210,6 +1211,7 @@ g_eli_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
 		sbuf_printf(sb, "%s<UsedKey>%u</UsedKey>\n", indent,
 		    sc->sc_nkey);
 	}
+	sbuf_printf(sb, "%s<Version>%u</Version>\n", indent, sc->sc_version);
 	sbuf_printf(sb, "%s<Crypto>", indent);
 	switch (sc->sc_crypto) {
 	case G_ELI_CRYPTO_HW:
diff --git a/sys/geom/eli/g_eli.h b/sys/geom/eli/g_eli.h
index 0f35cd6..0b48db2 100644
--- a/sys/geom/eli/g_eli.h
+++ b/sys/geom/eli/g_eli.h
@@ -43,6 +43,7 @@
 #include <sys/tree.h>
 #include <geom/geom.h>
 #else
+#include <assert.h>
 #include <stdio.h>
 #include <string.h>
 #include <strings.h>
@@ -166,6 +167,7 @@ struct g_eli_worker {
 
 struct g_eli_softc {
 	struct g_geom	*sc_geom;
+	u_int		 sc_version;
 	u_int		 sc_crypto;
 	uint8_t		 sc_mkey[G_ELI_DATAIVKEYLEN];
 	uint8_t		 sc_ekey[G_ELI_DATAKEYLEN];
@@ -217,14 +219,28 @@ struct g_eli_metadata {
 } __packed;
 #ifndef _OpenSSL_
 static __inline void
-eli_metadata_encode(struct g_eli_metadata *md, u_char *data)
+eli_metadata_encode_v0(struct g_eli_metadata *md, u_char **datap)
 {
-	MD5_CTX ctx;
 	u_char *p;
 
-	p = data;
-	bcopy(md->md_magic, p, sizeof(md->md_magic)); p += sizeof(md->md_magic);
-	le32enc(p, md->md_version);	p += sizeof(md->md_version);
+	p = *datap;
+	le32enc(p, md->md_flags);	p += sizeof(md->md_flags);
+	le16enc(p, md->md_ealgo);	p += sizeof(md->md_ealgo);
+	le16enc(p, md->md_keylen);	p += sizeof(md->md_keylen);
+	le64enc(p, md->md_provsize);	p += sizeof(md->md_provsize);
+	le32enc(p, md->md_sectorsize);	p += sizeof(md->md_sectorsize);
+	*p = md->md_keys;		p += sizeof(md->md_keys);
+	le32enc(p, md->md_iterations);	p += sizeof(md->md_iterations);
+	bcopy(md->md_salt, p, sizeof(md->md_salt)); p += sizeof(md->md_salt);
+	bcopy(md->md_mkeys, p, sizeof(md->md_mkeys)); p += sizeof(md->md_mkeys);
+	*datap = p;
+}
+static __inline void
+eli_metadata_encode_v1v2v3v4v5v6(struct g_eli_metadata *md, u_char **datap)
+{
+	u_char *p;
+
+	p = *datap;
 	le32enc(p, md->md_flags);	p += sizeof(md->md_flags);
 	le16enc(p, md->md_ealgo);	p += sizeof(md->md_ealgo);
 	le16enc(p, md->md_keylen);	p += sizeof(md->md_keylen);
@@ -235,6 +251,39 @@ eli_metadata_encode(struct g_eli_metadata *md, u_char *data)
 	le32enc(p, md->md_iterations);	p += sizeof(md->md_iterations);
 	bcopy(md->md_salt, p, sizeof(md->md_salt)); p += sizeof(md->md_salt);
 	bcopy(md->md_mkeys, p, sizeof(md->md_mkeys)); p += sizeof(md->md_mkeys);
+	*datap = p;
+}
+static __inline void
+eli_metadata_encode(struct g_eli_metadata *md, u_char *data)
+{
+	MD5_CTX ctx;
+	u_char *p;
+
+	p = data;
+	bcopy(md->md_magic, p, sizeof(md->md_magic));
+	p += sizeof(md->md_magic);
+	le32enc(p, md->md_version);
+	p += sizeof(md->md_version);
+	switch (md->md_version) {
+	case G_ELI_VERSION_00:
+		eli_metadata_encode_v0(md, &p);
+		break;
+	case G_ELI_VERSION_01:
+	case G_ELI_VERSION_02:
+	case G_ELI_VERSION_03:
+	case G_ELI_VERSION_04:
+	case G_ELI_VERSION_05:
+	case G_ELI_VERSION_06:
+		eli_metadata_encode_v1v2v3v4v5v6(md, &p);
+		break;
+	default:
+#ifdef _KERNEL
+		panic("%s: Unsupported version %u.", __func__,
+		    (u_int)md->md_version);
+#else
+		assert(!"Unsupported metadata version.");
+#endif
+	}
 	MD5Init(&ctx);
 	MD5Update(&ctx, data, p - data);
 	MD5Final(md->md_hash, &ctx);