Implement data integrity verification (data authentication) for geli(8).

Supported by:	Wheel Sp. z o.o. (http://www.wheel.pl)

1 files changed, 530 insertions, 0 deletions

diff --git a/sys/geom/eli/g_eli_integrity.c b/sys/geom/eli/g_eli_integrity.c
new file mode 100644
index 0000000..e30b0a8
--- /dev/null
+++ b/sys/geom/eli/g_eli_integrity.c
@@ -0,0 +1,530 @@
+/*-
+ * Copyright (c) 2005-2006 Pawel Jakub Dawidek <pjd@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/linker.h>
+#include <sys/module.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/bio.h>
+#include <sys/sysctl.h>
+#include <sys/malloc.h>
+#include <sys/kthread.h>
+#include <sys/proc.h>
+#include <sys/sched.h>
+#include <sys/smp.h>
+#include <sys/uio.h>
+#include <sys/vnode.h>
+
+#include <vm/uma.h>
+
+#include <geom/geom.h>
+#include <geom/eli/g_eli.h>
+#include <geom/eli/pkcs5v2.h>
+
+/*
+ * The data layout description when integrity verification is configured.
+ *
+ * One of the most important assumption here is that authenticated data and its
+ * HMAC has to be stored in the same place (namely in the same sector) to make
+ * it work reliable.
+ * The problem is that file systems work only with sectors that are multiple of
+ * 512 bytes and a power of two number.
+ * My idea to implement it is as follows.
+ * Let's store HMAC in sector. This is a must. This leaves us 480 bytes for
+ * data. We can't use that directly (ie. we can't create provider with 480 bytes
+ * sector size). We need another sector from where we take only 32 bytes of data
+ * and we store HMAC of this data as well. This takes two sectors from the
+ * original provider at the input and leaves us one sector of authenticated data
+ * at the output. Not very efficient, but you got the idea.
+ * Now, let's assume, we want to create provider with 4096 bytes sector.
+ * To output 4096 bytes of authenticated data we need 8x480 plus 1x256, so we
+ * need nine 512-bytes sectors at the input to get one 4096-bytes sector at the
+ * output. That's better. With 4096 bytes sector we can use 89% of size of the
+ * original provider. I find it as an acceptable cost.
+ * The reliability comes from the fact, that every HMAC stored inside the sector
+ * is calculated only for the data in the same sector, so its impossible to
+ * write new data and leave old HMAC or vice versa.
+ *
+ * And here is the picture:
+ *
+ * da0: +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+-----+
+ *      |32b |480b| |32b |480b| |32b |480b| |32b |480b| |32b |480b| |32b |480b| |32b |480b| |32b |480b| |32b |256b |
+ *      |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data| |HMAC|Data |
+ *      +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+----+ +----+-----+
+ *      |512 bytes| |512 bytes| |512 bytes| |512 bytes| |512 bytes| |512 bytes| |512 bytes| |512 bytes| |288 bytes |
+ *      +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ +---------+ |224 unused|
+ *                                                                                                      +----------+
+ * da0.eli: +----+----+----+----+----+----+----+----+----+
+ *          |480b|480b|480b|480b|480b|480b|480b|480b|256b|
+ *          +----+----+----+----+----+----+----+----+----+
+ *          |                 4096 bytes                 |
+ *          +--------------------------------------------+
+ *
+ * PS. You can use any sector size with geli(8). My example is using 4kB,
+ *     because it's most efficient. For 8kB sectors you need 2 extra sectors,
+ *     so the cost is the same as for 4kB sectors.
+ */
+
+/*
+ * Code paths:
+ * BIO_READ:
+ *	g_eli_start -> g_eli_auth_read -> g_io_request -> g_eli_read_done -> g_eli_auth_run -> g_eli_auth_read_done -> g_io_deliver
+ * BIO_WRITE:
+ *	g_eli_start -> g_eli_auth_run -> g_eli_auth_write_done -> g_io_request -> g_eli_write_done -> g_io_deliver
+ */
+
+MALLOC_DECLARE(M_ELI);
+
+/*
+ * Here we generate key for HMAC. Every sector has its own HMAC key, so it is
+ * not possible to copy sectors.
+ * We cannot depend on fact, that every sector has its own IV, because different
+ * IV doesn't change HMAC, when we use encrypt-then-authenticate method.
+ */
+static void
+g_eli_auth_keygen(struct g_eli_softc *sc, off_t offset, u_char *key)
+{
+	SHA256_CTX ctx;
+
+	/* Copy precalculated SHA256 context. */
+	bcopy(&sc->sc_akeyctx, &ctx, sizeof(ctx));
+	SHA256_Update(&ctx, (uint8_t *)&offset, sizeof(offset));
+	SHA256_Final(key, &ctx);
+}
+
+/*
+ * The function is called after we read and decrypt data.
+ *
+ * g_eli_start -> g_eli_auth_read -> g_io_request -> g_eli_read_done -> g_eli_auth_run -> G_ELI_AUTH_READ_DONE -> g_io_deliver
+ */
+static int
+g_eli_auth_read_done(struct cryptop *crp)
+{
+	struct bio *bp;
+
+	if (crp->crp_etype == EAGAIN) {
+		if (g_eli_crypto_rerun(crp) == 0)
+			return (0);
+	}
+	bp = (struct bio *)crp->crp_opaque;
+	bp->bio_inbed++;
+	if (crp->crp_etype == 0) {
+		bp->bio_completed += crp->crp_olen;
+		G_ELI_DEBUG(3, "Crypto READ request done (%d/%d) (add=%jd completed=%jd).",
+		    bp->bio_inbed, bp->bio_children, (intmax_t)crp->crp_olen, (intmax_t)bp->bio_completed);
+	} else {
+		G_ELI_DEBUG(1, "Crypto READ request failed (%d/%d) error=%d.",
+		    bp->bio_inbed, bp->bio_children, crp->crp_etype);
+		if (bp->bio_error == 0)
+			bp->bio_error = crp->crp_etype;
+	}
+	/*
+	 * Do we have all sectors already?
+	 */
+	if (bp->bio_inbed < bp->bio_children)
+		return (0);
+	if (bp->bio_error == 0) {
+		struct g_eli_softc *sc;
+		u_int i, lsec, nsec, data_secsize, decr_secsize, encr_secsize;
+		u_char *srcdata, *dstdata, *auth;
+		off_t coroff, corsize;
+
+		/*
+		 * Verify data integrity based on calculated and read HMACs.
+		 */
+		sc = bp->bio_to->geom->softc;
+		/* Sectorsize of decrypted provider eg. 4096. */
+		decr_secsize = bp->bio_to->sectorsize;
+		/* The real sectorsize of encrypted provider, eg. 512. */
+		encr_secsize = LIST_FIRST(&sc->sc_geom->consumer)->provider->sectorsize;
+		/* Number of data bytes in one encrypted sector, eg. 480. */
+		data_secsize = sc->sc_data_per_sector;
+		/* Number of sectors from decrypted provider, eg. 2. */
+		nsec = bp->bio_length / decr_secsize;
+		/* Number of sectors from encrypted provider, eg. 18. */
+		nsec = (nsec * sc->sc_bytes_per_sector) / encr_secsize;
+		/* Last sector number in every big sector, eg. 9. */
+		lsec = sc->sc_bytes_per_sector / encr_secsize;
+
+		srcdata = bp->bio_driver2;
+		dstdata = bp->bio_data;
+		auth = srcdata + encr_secsize * nsec;
+		coroff = -1;
+		corsize = 0;
+
+		for (i = 1; i <= nsec; i++) {
+			data_secsize = sc->sc_data_per_sector;
+			if ((i % lsec) == 0)
+				data_secsize = decr_secsize % data_secsize;
+			if (bcmp(srcdata, auth, sc->sc_alen) != 0) {
+				/*
+				 * Curruption detected, remember the offset if
+				 * this is the first corrupted sector and
+				 * increase size.
+				 */
+				if (bp->bio_error == 0)
+					bp->bio_error = -1;
+				if (coroff == -1) {
+					coroff = bp->bio_offset +
+					    (dstdata - (u_char *)bp->bio_data);
+				}
+				corsize += data_secsize;
+			} else {
+				/*
+				 * No curruption, good.
+				 * Report previous corruption if there was one.
+				 */
+				if (coroff != -1) {
+					G_ELI_DEBUG(0, "%s: %jd bytes "
+					    "corrupted at offset %jd.",
+					    sc->sc_name, (intmax_t)corsize,
+					    (intmax_t)coroff);
+					coroff = -1;
+					corsize = 0;
+				}
+				bcopy(srcdata + sc->sc_alen, dstdata,
+				    data_secsize);
+			}
+			srcdata += encr_secsize;
+			dstdata += data_secsize;
+			auth += sc->sc_alen;
+		}
+		/* Report previous corruption if there was one. */
+		if (coroff != -1) {
+			G_ELI_DEBUG(0, "%s: %jd bytes corrupted at offset %jd.",
+			    sc->sc_name, (intmax_t)corsize, (intmax_t)coroff);
+		}
+	}
+	free(bp->bio_driver2, M_ELI);
+	bp->bio_driver2 = NULL;
+	if (bp->bio_error != 0) {
+		if (bp->bio_error == -1)
+			bp->bio_error = EINVAL;
+		else {
+			G_ELI_LOGREQ(0, bp,
+			    "Crypto READ request failed (error=%d).",
+			    bp->bio_error);
+		}
+		bp->bio_completed = 0;
+	}
+	/*
+	 * Read is finished, send it up.
+	 */
+	g_io_deliver(bp, bp->bio_error);
+	return (0);
+}
+
+/*
+ * The function is called after data encryption.
+ *
+ * g_eli_start -> g_eli_auth_run -> G_ELI_AUTH_WRITE_DONE -> g_io_request -> g_eli_write_done -> g_io_deliver
+ */
+static int
+g_eli_auth_write_done(struct cryptop *crp)
+{
+	struct g_eli_softc *sc;
+	struct g_consumer *cp;
+	struct bio *bp, *cbp, *cbp2;
+	u_int nsec;
+
+	if (crp->crp_etype == EAGAIN) {
+		if (g_eli_crypto_rerun(crp) == 0)
+			return (0);
+	}
+	bp = (struct bio *)crp->crp_opaque;
+	bp->bio_inbed++;
+	if (crp->crp_etype == 0) {
+		G_ELI_DEBUG(3, "Crypto WRITE request done (%d/%d).",
+		    bp->bio_inbed, bp->bio_children);
+	} else {
+		G_ELI_DEBUG(1, "Crypto WRITE request failed (%d/%d) error=%d.",
+		    bp->bio_inbed, bp->bio_children, crp->crp_etype);
+		if (bp->bio_error == 0)
+			bp->bio_error = crp->crp_etype;
+	}
+	/*
+	 * All sectors are already encrypted?
+	 */
+	if (bp->bio_inbed < bp->bio_children)
+		return (0);
+	if (bp->bio_error != 0) {
+		G_ELI_LOGREQ(0, bp, "Crypto WRITE request failed (error=%d).",
+		    bp->bio_error);
+		free(bp->bio_driver2, M_ELI);
+		bp->bio_driver2 = NULL;
+		cbp = bp->bio_driver1;
+		bp->bio_driver1 = NULL;
+		g_destroy_bio(cbp);
+		g_io_deliver(bp, bp->bio_error);
+		return (0);
+	}
+	sc = bp->bio_to->geom->softc;
+	cp = LIST_FIRST(&sc->sc_geom->consumer);
+	cbp = bp->bio_driver1;
+	bp->bio_driver1 = NULL;
+	cbp->bio_to = cp->provider;
+	cbp->bio_done = g_eli_write_done;
+
+	/* Number of sectors from decrypted provider, eg. 1. */
+	nsec = bp->bio_length / bp->bio_to->sectorsize;
+	/* Number of sectors from encrypted provider, eg. 9. */
+	nsec = (nsec * sc->sc_bytes_per_sector) / cp->provider->sectorsize;
+
+	cbp->bio_length = cp->provider->sectorsize * nsec;
+	cbp->bio_offset = (bp->bio_offset / bp->bio_to->sectorsize) * sc->sc_bytes_per_sector;
+	cbp->bio_data = bp->bio_driver2;
+
+	/*
+	 * We write more than what is requested, so we have to be ready to write
+	 * more than MAXPHYS.
+	 */
+	cbp2 = NULL;
+	if (cbp->bio_length > MAXPHYS) {
+		cbp2 = g_duplicate_bio(bp);
+		cbp2->bio_length = cbp->bio_length - MAXPHYS;
+		cbp2->bio_data = cbp->bio_data + MAXPHYS;
+		cbp2->bio_offset = cbp->bio_offset + MAXPHYS;
+		cbp2->bio_to = cp->provider;
+		cbp2->bio_done = g_eli_write_done;
+		cbp->bio_length = MAXPHYS;
+	}
+	/*
+	 * Send encrypted data to the provider.
+	 */
+	G_ELI_LOGREQ(2, cbp, "Sending request.");
+	bp->bio_inbed = 0;
+	bp->bio_children = (cbp2 != NULL ? 2 : 1);
+	g_io_request(cbp, cp);
+	if (cbp2 != NULL) {
+		G_ELI_LOGREQ(2, cbp2, "Sending request.");
+		g_io_request(cbp2, cp);
+	}
+	return (0);
+}
+
+void
+g_eli_auth_read(struct g_eli_softc *sc, struct bio *bp)
+{
+	struct g_consumer *cp;
+	struct bio *cbp, *cbp2;
+	size_t size;
+	off_t nsec;
+
+	bp->bio_pflags = 0;
+
+	cp = LIST_FIRST(&sc->sc_geom->consumer);
+	cbp = bp->bio_driver1;
+	bp->bio_driver1 = NULL;
+	cbp->bio_to = cp->provider;
+	cbp->bio_done = g_eli_read_done;
+
+	/* Number of sectors from decrypted provider, eg. 1. */
+	nsec = bp->bio_length / bp->bio_to->sectorsize;
+	/* Number of sectors from encrypted provider, eg. 9. */
+	nsec = (nsec * sc->sc_bytes_per_sector) / cp->provider->sectorsize;
+
+	cbp->bio_length = cp->provider->sectorsize * nsec;
+	size = cbp->bio_length;
+	size += sc->sc_alen * nsec;
+	size += sizeof(struct cryptop) * nsec;
+	size += sizeof(struct cryptodesc) * nsec * 2;
+	size += G_ELI_AUTH_SECKEYLEN * nsec;
+	size += sizeof(struct uio) * nsec;
+	size += sizeof(struct iovec) * nsec;
+	cbp->bio_offset = (bp->bio_offset / bp->bio_to->sectorsize) * sc->sc_bytes_per_sector;
+	bp->bio_driver2 = malloc(size, M_ELI, M_WAITOK);
+	cbp->bio_data = bp->bio_driver2;
+
+	/*
+	 * We read more than what is requested, so we have to be ready to read
+	 * more than MAXPHYS.
+	 */
+	cbp2 = NULL;
+	if (cbp->bio_length > MAXPHYS) {
+		cbp2 = g_duplicate_bio(bp);
+		cbp2->bio_length = cbp->bio_length - MAXPHYS;
+		cbp2->bio_data = cbp->bio_data + MAXPHYS;
+		cbp2->bio_offset = cbp->bio_offset + MAXPHYS;
+		cbp2->bio_to = cp->provider;
+		cbp2->bio_done = g_eli_read_done;
+		cbp->bio_length = MAXPHYS;
+	}
+	/*
+	 * Read encrypted data from provider.
+	 */
+	G_ELI_LOGREQ(2, cbp, "Sending request.");
+	g_io_request(cbp, cp);
+	if (cbp2 != NULL) {
+		G_ELI_LOGREQ(2, cbp2, "Sending request.");
+		g_io_request(cbp2, cp);
+	}
+}
+
+/*
+ * This is the main function responsible for cryptography (ie. communication
+ * with crypto(9) subsystem).
+ */
+void
+g_eli_auth_run(struct g_eli_worker *wr, struct bio *bp)
+{
+	struct g_eli_softc *sc;
+	struct cryptop *crp;
+	struct cryptodesc *crde, *crda;
+	struct uio *uio;
+	struct iovec *iov;
+	u_int i, lsec, nsec, data_secsize, decr_secsize, encr_secsize;
+	off_t dstoff;
+	int err, error;
+	u_char *p, *data, *auth, *authkey, *plaindata;
+
+	G_ELI_LOGREQ(3, bp, "%s", __func__);
+
+	bp->bio_pflags = wr->w_number;
+	sc = wr->w_softc;
+	/* Sectorsize of decrypted provider eg. 4096. */
+	decr_secsize = bp->bio_to->sectorsize;
+	/* The real sectorsize of encrypted provider, eg. 512. */
+	encr_secsize = LIST_FIRST(&sc->sc_geom->consumer)->provider->sectorsize;
+	/* Number of data bytes in one encrypted sector, eg. 480. */
+	data_secsize = sc->sc_data_per_sector;
+	/* Number of sectors from decrypted provider, eg. 2. */
+	nsec = bp->bio_length / decr_secsize;
+	/* Number of sectors from encrypted provider, eg. 18. */
+	nsec = (nsec * sc->sc_bytes_per_sector) / encr_secsize;
+	/* Last sector number in every big sector, eg. 9. */
+	lsec = sc->sc_bytes_per_sector / encr_secsize;
+	/* Destination offset, used for IV generation. */
+	dstoff = (bp->bio_offset / bp->bio_to->sectorsize) * sc->sc_bytes_per_sector;
+
+	plaindata = bp->bio_data;
+	if (bp->bio_cmd == BIO_READ) {
+		data = bp->bio_driver2;
+		auth = data + encr_secsize * nsec;
+		p = auth + sc->sc_alen * nsec;
+	} else {
+		size_t size;
+
+		size = encr_secsize * nsec;
+		size += sizeof(*crp) * nsec;
+		size += sizeof(*crde) * nsec;
+		size += sizeof(*crda) * nsec;
+		size += G_ELI_AUTH_SECKEYLEN * nsec;
+		size += sizeof(*uio) * nsec;
+		size += sizeof(*iov) * nsec;
+		data = malloc(size, M_ELI, M_WAITOK);
+		bp->bio_driver2 = data;
+		p = data + encr_secsize * nsec;
+	}
+	bp->bio_inbed = 0;
+	bp->bio_children = nsec;
+
+	error = 0;
+	for (i = 1; i <= nsec; i++, dstoff += encr_secsize) {
+		crp = (struct cryptop *)p;	p += sizeof(*crp);
+		crde = (struct cryptodesc *)p;	p += sizeof(*crde);
+		crda = (struct cryptodesc *)p;	p += sizeof(*crda);
+		authkey = (u_char *)p;		p += G_ELI_AUTH_SECKEYLEN;
+		uio = (struct uio *)p;		p += sizeof(*uio);
+		iov = (struct iovec *)p;	p += sizeof(*iov);
+
+		data_secsize = sc->sc_data_per_sector;
+		if ((i % lsec) == 0)
+			data_secsize = decr_secsize % data_secsize;
+
+		if (bp->bio_cmd == BIO_READ) {
+			/* Remember read HMAC. */
+			bcopy(data, auth, sc->sc_alen);
+			auth += sc->sc_alen;
+			/* TODO: bzero(9) can be commented out later. */
+			bzero(data, sc->sc_alen);
+		} else {
+			bcopy(plaindata, data + sc->sc_alen, data_secsize);
+			plaindata += data_secsize;
+		}
+
+		iov->iov_len = sc->sc_alen + data_secsize;
+		iov->iov_base = data;
+		data += encr_secsize;
+
+		uio->uio_iov = iov;
+		uio->uio_iovcnt = 1;
+		uio->uio_segflg = UIO_SYSSPACE;
+		uio->uio_resid = iov->iov_len;
+
+		crp->crp_sid = wr->w_sid;
+		crp->crp_ilen = data_secsize;
+		crp->crp_olen = data_secsize;
+		crp->crp_opaque = (void *)bp;
+		crp->crp_buf = (void *)uio;
+		crp->crp_flags = CRYPTO_F_IOV | CRYPTO_F_CBIFSYNC | CRYPTO_F_REL;
+		if (g_eli_batch)
+			crp->crp_flags |= CRYPTO_F_BATCH;
+		if (bp->bio_cmd == BIO_WRITE) {
+			crp->crp_callback = g_eli_auth_write_done;
+			crp->crp_desc = crde;
+			crde->crd_next = crda;
+			crda->crd_next = NULL;
+		} else {
+			crp->crp_callback = g_eli_auth_read_done;
+			crp->crp_desc = crda;
+			crda->crd_next = crde;
+			crde->crd_next = NULL;
+		}
+
+		crde->crd_skip = sc->sc_alen;
+		crde->crd_len = data_secsize;
+		crde->crd_flags = CRD_F_IV_EXPLICIT | CRD_F_IV_PRESENT;
+		if (bp->bio_cmd == BIO_WRITE)
+			crde->crd_flags |= CRD_F_ENCRYPT;
+		crde->crd_alg = sc->sc_ealgo;
+		crde->crd_key = sc->sc_ekey;
+		crde->crd_klen = sc->sc_ekeylen;
+		g_eli_crypto_ivgen(sc, dstoff, crde->crd_iv,
+		    sizeof(crde->crd_iv));
+
+		crda->crd_skip = sc->sc_alen;
+		crda->crd_len = data_secsize;
+		crda->crd_inject = 0;
+		crda->crd_flags = CRD_F_KEY_EXPLICIT;
+		crda->crd_alg = sc->sc_aalgo;
+		g_eli_auth_keygen(sc, dstoff, authkey);
+		crda->crd_key = authkey;
+		crda->crd_klen = G_ELI_AUTH_SECKEYLEN * 8;
+
+		crp->crp_etype = 0;
+		err = crypto_dispatch(crp);
+		if (err != 0 && error == 0)
+			error = err;
+	}
+	if (bp->bio_error == 0)
+		bp->bio_error = error;
+}