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/*-
* Copyright (c) 2005-2011 Pawel Jakub Dawidek <pawel@dawidek.net>
* 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: release/9.1.0/sys/geom/eli/g_eli_integrity.c 235498 2012-05-16 00:37:37Z eadler $");
#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 g_eli_softc *sc;
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;
}
sc = bp->bio_to->geom->softc;
g_eli_key_drop(sc, crp->crp_desc->crd_next->crd_key);
/*
* Do we have all sectors already?
*/
if (bp->bio_inbed < bp->bio_children)
return (0);
if (bp->bio_error == 0) {
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.
*/
/* 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: Failed to authenticate %jd "
"bytes of data 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: Failed to authenticate %jd "
"bytes of data 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);
atomic_subtract_int(&sc->sc_inflight, 1);
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;
}
sc = bp->bio_to->geom->softc;
g_eli_key_drop(sc, crp->crp_desc->crd_key);
/*
* 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);
atomic_subtract_int(&sc->sc_inflight, 1);
return (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_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).
*
* 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
*/
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;
auth = NULL; /* Silence compiler warning. */
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 = uio->uio_resid;
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 ((sc->sc_flags & G_ELI_FLAG_FIRST_KEY) == 0)
crde->crd_flags |= CRD_F_KEY_EXPLICIT;
if (bp->bio_cmd == BIO_WRITE)
crde->crd_flags |= CRD_F_ENCRYPT;
crde->crd_alg = sc->sc_ealgo;
crde->crd_key = g_eli_key_hold(sc, dstoff, encr_secsize);
crde->crd_klen = sc->sc_ekeylen;
if (sc->sc_ealgo == CRYPTO_AES_XTS)
crde->crd_klen <<= 1;
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;
}