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|
/* $OpenBSD: vioqcow2.c,v 1.14 2020/10/19 19:06:49 naddy Exp $ */
/*
* Copyright (c) 2018 Ori Bernstein <ori@eigenstate.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <machine/vmmvar.h>
#include <dev/pci/pcireg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <libgen.h>
#include <err.h>
#include <errno.h>
#include "vmd.h"
#include "vmm.h"
#include "virtio.h"
#define QCOW2_COMPRESSED 0x4000000000000000ull
#define QCOW2_INPLACE 0x8000000000000000ull
#define QCOW2_DIRTY (1 << 0)
#define QCOW2_CORRUPT (1 << 1)
enum {
ICFEATURE_DIRTY = 1 << 0,
ICFEATURE_CORRUPT = 1 << 1,
};
enum {
ACFEATURE_BITEXT = 1 << 0,
};
struct qcheader {
char magic[4];
uint32_t version;
uint64_t backingoff;
uint32_t backingsz;
uint32_t clustershift;
uint64_t disksz;
uint32_t cryptmethod;
uint32_t l1sz;
uint64_t l1off;
uint64_t refoff;
uint32_t refsz;
uint32_t snapcount;
uint64_t snapsz;
/* v3 additions */
uint64_t incompatfeatures;
uint64_t compatfeatures;
uint64_t autoclearfeatures;
uint32_t reforder; /* Bits = 1 << reforder */
uint32_t headersz;
} __packed;
struct qcdisk {
pthread_rwlock_t lock;
struct qcdisk *base;
struct qcheader header;
int fd;
uint64_t *l1;
off_t end;
off_t clustersz;
off_t disksz; /* In bytes */
uint32_t cryptmethod;
uint32_t l1sz;
off_t l1off;
off_t refoff;
off_t refsz;
uint32_t nsnap;
off_t snapoff;
/* v3 features */
uint64_t incompatfeatures;
uint64_t autoclearfeatures;
uint32_t refssz;
uint32_t headersz;
};
extern char *__progname;
static off_t xlate(struct qcdisk *, off_t, int *);
static void copy_cluster(struct qcdisk *, struct qcdisk *, off_t, off_t);
static void inc_refs(struct qcdisk *, off_t, int);
static off_t mkcluster(struct qcdisk *, struct qcdisk *, off_t, off_t);
static int qc2_open(struct qcdisk *, int *, size_t);
static ssize_t qc2_pread(void *, char *, size_t, off_t);
static ssize_t qc2_pwrite(void *, char *, size_t, off_t);
static void qc2_close(void *, int);
/*
* Initializes a raw disk image backing file from an fd.
* Stores the number of 512 byte sectors in *szp,
* returning -1 for error, 0 for success.
*
* May open snapshot base images.
*/
int
virtio_qcow2_init(struct virtio_backing *file, off_t *szp, int *fd, size_t nfd)
{
struct qcdisk *diskp;
diskp = malloc(sizeof(struct qcdisk));
if (diskp == NULL)
return -1;
if (qc2_open(diskp, fd, nfd) == -1) {
log_warnx("could not open qcow2 disk");
return -1;
}
file->p = diskp;
file->pread = qc2_pread;
file->pwrite = qc2_pwrite;
file->close = qc2_close;
*szp = diskp->disksz;
return 0;
}
/*
* Return the path to the base image given a disk image.
* Called from vmctl.
*/
ssize_t
virtio_qcow2_get_base(int fd, char *path, size_t npath, const char *dpath)
{
char dpathbuf[PATH_MAX];
char expanded[PATH_MAX];
struct qcheader header;
uint64_t backingoff;
uint32_t backingsz;
char *s = NULL;
if (pread(fd, &header, sizeof(header), 0) != sizeof(header)) {
log_warnx("short read on header");
return -1;
}
if (strncmp(header.magic, VM_MAGIC_QCOW, strlen(VM_MAGIC_QCOW)) != 0) {
log_warnx("invalid magic numbers");
return -1;
}
backingoff = be64toh(header.backingoff);
backingsz = be32toh(header.backingsz);
if (backingsz == 0)
return 0;
if (backingsz >= npath - 1) {
log_warnx("snapshot path too long");
return -1;
}
if (pread(fd, path, backingsz, backingoff) != backingsz) {
log_warnx("could not read snapshot base name");
return -1;
}
path[backingsz] = '\0';
/*
* Relative paths should be interpreted relative to the disk image,
* rather than relative to the directory vmd happens to be running in,
* since this is the only userful interpretation.
*/
if (path[0] == '/') {
if (realpath(path, expanded) == NULL ||
strlcpy(path, expanded, npath) >= npath) {
log_warnx("unable to resolve %s", path);
return -1;
}
} else {
if (strlcpy(dpathbuf, dpath, sizeof(dpathbuf)) >=
sizeof(dpathbuf)) {
log_warnx("path too long: %s", dpath);
return -1;
}
s = dirname(dpathbuf);
if (snprintf(expanded, sizeof(expanded),
"%s/%s", s, path) >= (int)sizeof(expanded)) {
log_warnx("path too long: %s/%s", s, path);
return -1;
}
if (npath < PATH_MAX ||
realpath(expanded, path) == NULL) {
log_warnx("unable to resolve %s", path);
return -1;
}
}
return strlen(path);
}
static int
qc2_open(struct qcdisk *disk, int *fds, size_t nfd)
{
char basepath[PATH_MAX];
struct stat st;
struct qcheader header;
uint64_t backingoff;
uint32_t backingsz;
off_t i;
int version, fd;
pthread_rwlock_init(&disk->lock, NULL);
fd = fds[0];
disk->fd = fd;
disk->base = NULL;
disk->l1 = NULL;
if (pread(fd, &header, sizeof(header), 0) != sizeof(header))
fatalx("short read on header");
if (strncmp(header.magic, VM_MAGIC_QCOW, strlen(VM_MAGIC_QCOW)) != 0)
fatalx("invalid magic numbers");
disk->clustersz = (1ull << be32toh(header.clustershift));
disk->disksz = be64toh(header.disksz);
disk->cryptmethod = be32toh(header.cryptmethod);
disk->l1sz = be32toh(header.l1sz);
disk->l1off = be64toh(header.l1off);
disk->refsz = be32toh(header.refsz);
disk->refoff = be64toh(header.refoff);
disk->nsnap = be32toh(header.snapcount);
disk->snapoff = be64toh(header.snapsz);
/*
* The additional features here are defined as 0 in the v2 format,
* so as long as we clear the buffer before parsing, we don't need
* to check versions here.
*/
disk->incompatfeatures = be64toh(header.incompatfeatures);
disk->autoclearfeatures = be64toh(header.autoclearfeatures);
disk->refssz = be32toh(header.refsz);
disk->headersz = be32toh(header.headersz);
/*
* We only know about the dirty or corrupt bits here.
*/
if (disk->incompatfeatures & ~(QCOW2_DIRTY|QCOW2_CORRUPT))
fatalx("unsupported features %llx",
disk->incompatfeatures & ~(QCOW2_DIRTY|QCOW2_CORRUPT));
if (be32toh(header.reforder) != 4)
fatalx("unsupported refcount size\n");
disk->l1 = calloc(disk->l1sz, sizeof(*disk->l1));
if (!disk->l1)
fatal("%s: could not allocate l1 table", __func__);
if (pread(disk->fd, disk->l1, 8 * disk->l1sz, disk->l1off)
!= 8 * disk->l1sz)
fatalx("%s: unable to read qcow2 L1 table", __func__);
for (i = 0; i < disk->l1sz; i++)
disk->l1[i] = be64toh(disk->l1[i]);
version = be32toh(header.version);
if (version != 2 && version != 3)
fatalx("%s: unknown qcow2 version %d", __func__, version);
backingoff = be64toh(header.backingoff);
backingsz = be32toh(header.backingsz);
if (backingsz != 0) {
if (backingsz >= sizeof(basepath) - 1) {
fatalx("%s: snapshot path too long", __func__);
}
if (pread(fd, basepath, backingsz, backingoff) != backingsz) {
fatalx("%s: could not read snapshot base name",
__func__);
}
basepath[backingsz] = 0;
if (nfd <= 1) {
fatalx("%s: missing base image %s", __func__,
basepath);
}
disk->base = calloc(1, sizeof(struct qcdisk));
if (!disk->base)
fatal("%s: could not open %s", __func__, basepath);
if (qc2_open(disk->base, fds + 1, nfd - 1) == -1)
fatalx("%s: could not open %s", __func__, basepath);
if (disk->base->clustersz != disk->clustersz)
fatalx("%s: all disk parts must share clustersize",
__func__);
}
if (fstat(fd, &st) == -1)
fatal("%s: unable to stat disk", __func__);
disk->end = st.st_size;
log_debug("%s: qcow2 disk version %d size %lld end %lld snap %d",
__func__, version, disk->disksz, disk->end, disk->nsnap);
return 0;
}
static ssize_t
qc2_pread(void *p, char *buf, size_t len, off_t off)
{
struct qcdisk *disk, *d;
off_t phys_off, end, cluster_off;
ssize_t sz, rem;
disk = p;
end = off + len;
if (off < 0 || end > disk->disksz)
return -1;
/* handle head chunk separately */
rem = len;
while (off != end) {
for (d = disk; d; d = d->base)
if ((phys_off = xlate(d, off, NULL)) > 0)
break;
/* Break out into chunks. This handles
* three cases:
*
* |----+====|========|====+-----|
*
* Either we are at the start of the read,
* and the cluster has some leading bytes.
* This means that we are reading the tail
* of the cluster, and our size is:
*
* clustersz - (off % clustersz).
*
* Otherwise, we're reading the middle section.
* We're already aligned here, so we can just
* read the whole cluster size. Or we're at the
* tail, at which point we just want to read the
* remaining bytes.
*/
cluster_off = off % disk->clustersz;
sz = disk->clustersz - cluster_off;
if (sz > rem)
sz = rem;
/*
* If we're within the disk, but don't have backing bytes,
* just read back zeros.
*/
if (!d)
bzero(buf, sz);
else if (pread(d->fd, buf, sz, phys_off) != sz)
return -1;
off += sz;
buf += sz;
rem -= sz;
}
return len;
}
ssize_t
qc2_pwrite(void *p, char *buf, size_t len, off_t off)
{
struct qcdisk *disk, *d;
off_t phys_off, cluster_off, end;
ssize_t sz, rem;
int inplace;
d = p;
disk = p;
inplace = 1;
end = off + len;
if (off < 0 || end > disk->disksz)
return -1;
rem = len;
while (off != end) {
/* See the read code for a summary of the computation */
cluster_off = off % disk->clustersz;
sz = disk->clustersz - cluster_off;
if (sz > rem)
sz = rem;
phys_off = xlate(disk, off, &inplace);
if (phys_off == -1)
return -1;
/*
* If we couldn't find the cluster in the writable disk,
* see if it exists in the base image. If it does, we
* need to copy it before the write. The copy happens
* in the '!inplace' if clause below te search.
*/
if (phys_off == 0)
for (d = disk->base; d; d = d->base)
if ((phys_off = xlate(d, off, NULL)) > 0)
break;
if (!inplace || phys_off == 0)
phys_off = mkcluster(disk, d, off, phys_off);
if (phys_off == -1)
return -1;
if (phys_off < disk->clustersz)
fatalx("%s: writing reserved cluster", __func__);
if (pwrite(disk->fd, buf, sz, phys_off) != sz)
return -1;
off += sz;
buf += sz;
rem -= sz;
}
return len;
}
static void
qc2_close(void *p, int stayopen)
{
struct qcdisk *disk;
disk = p;
if (disk->base)
qc2_close(disk->base, stayopen);
if (!stayopen)
close(disk->fd);
free(disk->l1);
free(disk);
}
/*
* Translates a virtual offset into an on-disk offset.
* Returns:
* -1 on error
* 0 on 'not found'
* >0 on found
*/
static off_t
xlate(struct qcdisk *disk, off_t off, int *inplace)
{
off_t l2sz, l1off, l2tab, l2off, cluster, clusteroff;
uint64_t buf;
/*
* Clear out inplace flag -- xlate misses should not
* be flagged as updatable in place. We will still
* return 0 from them, but this leaves less surprises
* in the API.
*/
if (inplace)
*inplace = 0;
pthread_rwlock_rdlock(&disk->lock);
if (off < 0)
goto err;
l2sz = disk->clustersz / 8;
l1off = (off / disk->clustersz) / l2sz;
if (l1off >= disk->l1sz)
goto err;
l2tab = disk->l1[l1off];
l2tab &= ~QCOW2_INPLACE;
if (l2tab == 0) {
pthread_rwlock_unlock(&disk->lock);
return 0;
}
l2off = (off / disk->clustersz) % l2sz;
pread(disk->fd, &buf, sizeof(buf), l2tab + l2off * 8);
cluster = be64toh(buf);
/*
* cluster may be 0, but all future operations don't affect
* the return value.
*/
if (inplace)
*inplace = !!(cluster & QCOW2_INPLACE);
if (cluster & QCOW2_COMPRESSED)
fatalx("%s: compressed clusters unsupported", __func__);
pthread_rwlock_unlock(&disk->lock);
clusteroff = 0;
cluster &= ~QCOW2_INPLACE;
if (cluster)
clusteroff = off % disk->clustersz;
return cluster + clusteroff;
err:
pthread_rwlock_unlock(&disk->lock);
return -1;
}
/*
* Allocates a new cluster on disk, creating a new L2 table
* if needed. The cluster starts off with a refs of one,
* and the writable bit set.
*
* Returns -1 on error, and the physical address within the
* cluster of the write offset if it exists.
*/
static off_t
mkcluster(struct qcdisk *disk, struct qcdisk *base, off_t off, off_t src_phys)
{
off_t l2sz, l1off, l2tab, l2off, cluster, clusteroff, orig;
uint64_t buf;
int fd;
pthread_rwlock_wrlock(&disk->lock);
cluster = -1;
fd = disk->fd;
/* L1 entries always exist */
l2sz = disk->clustersz / 8;
l1off = off / (disk->clustersz * l2sz);
if (l1off >= disk->l1sz)
fatalx("l1 offset outside disk");
disk->end = (disk->end + disk->clustersz - 1) & ~(disk->clustersz - 1);
l2tab = disk->l1[l1off];
l2off = (off / disk->clustersz) % l2sz;
/* We may need to create or clone an L2 entry to map the block */
if (l2tab == 0 || (l2tab & QCOW2_INPLACE) == 0) {
orig = l2tab & ~QCOW2_INPLACE;
l2tab = disk->end;
disk->end += disk->clustersz;
if (ftruncate(disk->fd, disk->end) == -1)
fatal("%s: ftruncate failed", __func__);
/*
* If we translated, found a L2 entry, but it needed to
* be copied, copy it.
*/
if (orig != 0)
copy_cluster(disk, disk, l2tab, orig);
/* Update l1 -- we flush it later */
disk->l1[l1off] = l2tab | QCOW2_INPLACE;
inc_refs(disk, l2tab, 1);
}
l2tab &= ~QCOW2_INPLACE;
/* Grow the disk */
if (ftruncate(disk->fd, disk->end + disk->clustersz) < 0)
fatalx("%s: could not grow disk", __func__);
if (src_phys > 0)
copy_cluster(disk, base, disk->end, src_phys);
cluster = disk->end;
disk->end += disk->clustersz;
buf = htobe64(cluster | QCOW2_INPLACE);
if (pwrite(disk->fd, &buf, sizeof(buf), l2tab + l2off * 8) != 8)
fatalx("%s: could not write cluster", __func__);
/* TODO: lazily sync: currently VMD doesn't close things */
buf = htobe64(disk->l1[l1off]);
if (pwrite(disk->fd, &buf, sizeof(buf), disk->l1off + 8 * l1off) != 8)
fatalx("%s: could not write l1", __func__);
inc_refs(disk, cluster, 1);
pthread_rwlock_unlock(&disk->lock);
clusteroff = off % disk->clustersz;
if (cluster + clusteroff < disk->clustersz)
fatalx("write would clobber header");
return cluster + clusteroff;
}
/* Copies a cluster containing src to dst. Src and dst need not be aligned. */
static void
copy_cluster(struct qcdisk *disk, struct qcdisk *base, off_t dst, off_t src)
{
char *scratch;
scratch = malloc(disk->clustersz);
if (!scratch)
fatal("out of memory");
src &= ~(disk->clustersz - 1);
dst &= ~(disk->clustersz - 1);
if (pread(base->fd, scratch, disk->clustersz, src) == -1)
fatal("%s: could not read cluster", __func__);
if (pwrite(disk->fd, scratch, disk->clustersz, dst) == -1)
fatal("%s: could not write cluster", __func__);
free(scratch);
}
static void
inc_refs(struct qcdisk *disk, off_t off, int newcluster)
{
off_t l1off, l1idx, l2idx, l2cluster;
size_t nper;
uint16_t refs;
uint64_t buf;
off &= ~QCOW2_INPLACE;
nper = disk->clustersz / 2;
l1idx = (off / disk->clustersz) / nper;
l2idx = (off / disk->clustersz) % nper;
l1off = disk->refoff + 8 * l1idx;
if (pread(disk->fd, &buf, sizeof(buf), l1off) != 8)
fatal("could not read refs");
l2cluster = be64toh(buf);
if (l2cluster == 0) {
l2cluster = disk->end;
disk->end += disk->clustersz;
if (ftruncate(disk->fd, disk->end) < 0)
fatal("%s: failed to allocate ref block", __func__);
buf = htobe64(l2cluster);
if (pwrite(disk->fd, &buf, sizeof(buf), l1off) != 8)
fatal("%s: failed to write ref block", __func__);
}
refs = 1;
if (!newcluster) {
if (pread(disk->fd, &refs, sizeof(refs),
l2cluster + 2 * l2idx) != 2)
fatal("could not read ref cluster");
refs = be16toh(refs) + 1;
}
refs = htobe16(refs);
if (pwrite(disk->fd, &refs, sizeof(refs), l2cluster + 2 * l2idx) != 2)
fatal("%s: could not write ref block", __func__);
}
/*
* virtio_qcow2_create
*
* Create an empty qcow2 imagefile with the specified path and size.
*
* Parameters:
* imgfile_path: path to the image file to create
* imgsize : size of the image file to create (in MB)
*
* Return:
* EEXIST: The requested image file already exists
* 0 : Image file successfully created
* Exxxx : Various other Exxxx errno codes due to other I/O errors
*/
int
virtio_qcow2_create(const char *imgfile_path,
const char *base_path, long imgsize)
{
struct qcheader {
char magic[4];
uint32_t version;
uint64_t backingoff;
uint32_t backingsz;
uint32_t clustershift;
uint64_t disksz;
uint32_t cryptmethod;
uint32_t l1sz;
uint64_t l1off;
uint64_t refoff;
uint32_t refsz;
uint32_t snapcount;
uint64_t snapsz;
/* v3 additions */
uint64_t incompatfeatures;
uint64_t compatfeatures;
uint64_t autoclearfeatures;
uint32_t reforder;
uint32_t headersz;
} __packed hdr, basehdr;
int fd, ret;
ssize_t base_len;
uint64_t l1sz, refsz, disksz, initsz, clustersz;
uint64_t l1off, refoff, v, i, l1entrysz, refentrysz;
uint16_t refs;
disksz = 1024 * 1024 * imgsize;
if (base_path) {
fd = open(base_path, O_RDONLY);
if (read(fd, &basehdr, sizeof(basehdr)) != sizeof(basehdr))
err(1, "failure to read base image header");
close(fd);
if (strncmp(basehdr.magic,
VM_MAGIC_QCOW, strlen(VM_MAGIC_QCOW)) != 0)
errx(1, "base image is not a qcow2 file");
if (!disksz)
disksz = betoh64(basehdr.disksz);
else if (disksz != betoh64(basehdr.disksz))
errx(1, "base size does not match requested size");
}
if (!base_path && !disksz)
errx(1, "missing disk size");
clustersz = (1<<16);
l1off = ALIGNSZ(sizeof(hdr), clustersz);
l1entrysz = clustersz * clustersz / 8;
l1sz = (disksz + l1entrysz - 1) / l1entrysz;
refoff = ALIGNSZ(l1off + 8*l1sz, clustersz);
refentrysz = clustersz * clustersz * clustersz / 2;
refsz = (disksz + refentrysz - 1) / refentrysz;
initsz = ALIGNSZ(refoff + refsz*clustersz, clustersz);
base_len = base_path ? strlen(base_path) : 0;
memcpy(hdr.magic, VM_MAGIC_QCOW, strlen(VM_MAGIC_QCOW));
hdr.version = htobe32(3);
hdr.backingoff = htobe64(base_path ? sizeof(hdr) : 0);
hdr.backingsz = htobe32(base_len);
hdr.clustershift = htobe32(16);
hdr.disksz = htobe64(disksz);
hdr.cryptmethod = htobe32(0);
hdr.l1sz = htobe32(l1sz);
hdr.l1off = htobe64(l1off);
hdr.refoff = htobe64(refoff);
hdr.refsz = htobe32(refsz);
hdr.snapcount = htobe32(0);
hdr.snapsz = htobe64(0);
hdr.incompatfeatures = htobe64(0);
hdr.compatfeatures = htobe64(0);
hdr.autoclearfeatures = htobe64(0);
hdr.reforder = htobe32(4);
hdr.headersz = htobe32(sizeof(hdr));
/* Refuse to overwrite an existing image */
fd = open(imgfile_path, O_RDWR | O_CREAT | O_TRUNC | O_EXCL,
S_IRUSR | S_IWUSR);
if (fd == -1)
return (errno);
/* Write out the header */
if (write(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
goto error;
/* Add the base image */
if (base_path && write(fd, base_path, base_len) != base_len)
goto error;
/* Extend to desired size, and add one refcount cluster */
if (ftruncate(fd, (off_t)initsz + clustersz) == -1)
goto error;
/*
* Paranoia: if our disk image takes more than one cluster
* to refcount the initial image, fail.
*/
if (initsz/clustersz > clustersz/2) {
errno = ERANGE;
goto error;
}
/* Add a refcount block, and refcount ourselves. */
v = htobe64(initsz);
if (pwrite(fd, &v, 8, refoff) != 8)
goto error;
for (i = 0; i < initsz/clustersz + 1; i++) {
refs = htobe16(1);
if (pwrite(fd, &refs, 2, initsz + 2*i) != 2)
goto error;
}
ret = close(fd);
return (ret);
error:
ret = errno;
close(fd);
unlink(imgfile_path);
return (errno);
}
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