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dissect: optionally, only look for GPT partition tables, nothing else 

This is useful for reusing the dissector logic in the gpt-auto-discovery logic:
there we really don't want to use MBR or naked file systems as root device.
This commit is contained in:
Lennart Poettering 2016-12-09 18:39:15 +01:00
parent 6f4e2f97d7
commit 9b6deb03fc
6 changed files with 58 additions and 50 deletions
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2
src/dissect/dissect.c
View File

@ -191,7 +191,7 @@ int main(int argc, char *argv[]) {
goto finish;
}
r = dissect_image(d->fd, arg_root_hash, arg_root_hash_size, &m);
r = dissect_image(d->fd, arg_root_hash, arg_root_hash_size, 0, &m);
if (r == -ENOPKG) {
log_error_errno(r, "Couldn't identify a suitable partition table or file system in %s.", arg_image);
goto finish;

2
src/machine/image-dbus.c
View File

@ -336,7 +336,7 @@ static int raw_image_get_os_release(Image *image, char ***ret, sd_bus_error *err
if (r < 0)
return sd_bus_error_set_errnof(error, r, "Failed to set up loop block device for %s: %m", image->path);
r = dissect_image(d->fd, NULL, 0, &m);
r = dissect_image(d->fd, NULL, 0, 0, &m);
if (r == -ENOPKG)
return sd_bus_error_set_errnof(error, r, "Disk image %s not understood: %m", image->path);
if (r < 0)

2
src/nspawn/nspawn.c
View File

@ -3743,7 +3743,7 @@ int main(int argc, char *argv[]) {
goto finish;
}
r = dissect_image(loop->fd, arg_root_hash, arg_root_hash_size, &dissected_image);
r = dissect_image(loop->fd, arg_root_hash, arg_root_hash_size, 0, &dissected_image);
if (r == -ENOPKG) {
log_error_errno(r, "Could not find a suitable file system or partition table in image: %s", arg_image);

97
src/shared/dissect-image.c
View File

@ -84,7 +84,7 @@ not_found:
#endif
}
int dissect_image(int fd, const void *root_hash, size_t root_hash_size, DissectedImage **ret) {
int dissect_image(int fd, const void *root_hash, size_t root_hash_size, DissectImageFlags flags, DissectedImage **ret) {
#ifdef HAVE_BLKID
sd_id128_t root_uuid = SD_ID128_NULL, verity_uuid = SD_ID128_NULL;
@ -95,7 +95,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
_cleanup_blkid_free_probe_ blkid_probe b = NULL;
_cleanup_udev_unref_ struct udev *udev = NULL;
_cleanup_free_ char *generic_node = NULL;
const char *pttype = NULL, *usage = NULL;
const char *pttype = NULL;
struct udev_list_entry *first, *item;
blkid_partlist pl;
int r, generic_nr;
@ -147,8 +147,12 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
return -errno;
}
blkid_probe_enable_superblocks(b, 1);
blkid_probe_set_superblocks_flags(b, BLKID_SUBLKS_TYPE|BLKID_SUBLKS_USAGE);
if ((flags & DISSECT_IMAGE_GPT_ONLY) == 0) {
/* Look for file system superblocks, unless we only shall look for GPT partition tables */
blkid_probe_enable_superblocks(b, 1);
blkid_probe_set_superblocks_flags(b, BLKID_SUBLKS_TYPE|BLKID_SUBLKS_USAGE);
}
blkid_probe_enable_partitions(b, 1);
blkid_probe_set_partitions_flags(b, BLKID_PARTS_ENTRY_DETAILS);
@ -169,40 +173,44 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
if (!m)
return -ENOMEM;
(void) blkid_probe_lookup_value(b, "USAGE", &usage, NULL);
if (STRPTR_IN_SET(usage, "filesystem", "crypto")) {
_cleanup_free_ char *t = NULL, *n = NULL;
const char *fstype = NULL;
if ((flags & DISSECT_IMAGE_GPT_ONLY) == 0) {
const char *usage = NULL;
/* OK, we have found a file system, that's our root partition then. */
(void) blkid_probe_lookup_value(b, "TYPE", &fstype, NULL);
(void) blkid_probe_lookup_value(b, "USAGE", &usage, NULL);
if (STRPTR_IN_SET(usage, "filesystem", "crypto")) {
_cleanup_free_ char *t = NULL, *n = NULL;
const char *fstype = NULL;
if (fstype) {
t = strdup(fstype);
if (!t)
/* OK, we have found a file system, that's our root partition then. */
(void) blkid_probe_lookup_value(b, "TYPE", &fstype, NULL);
if (fstype) {
t = strdup(fstype);
if (!t)
return -ENOMEM;
}
if (asprintf(&n, "/dev/block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
return -ENOMEM;
m->partitions[PARTITION_ROOT] = (DissectedPartition) {
.found = true,
.rw = true,
.partno = -1,
.architecture = _ARCHITECTURE_INVALID,
.fstype = t,
.node = n,
};
t = n = NULL;
m->encrypted = streq(fstype, "crypto_LUKS");
*ret = m;
m = NULL;
return 0;
}
if (asprintf(&n, "/dev/block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
return -ENOMEM;
m->partitions[PARTITION_ROOT] = (DissectedPartition) {
.found = true,
.rw = true,
.partno = -1,
.architecture = _ARCHITECTURE_INVALID,
.fstype = t,
.node = n,
};
t = n = NULL;
m->encrypted = streq(fstype, "crypto_LUKS");
*ret = m;
m = NULL;
return 0;
}
(void) blkid_probe_lookup_value(b, "PTTYPE", &pttype, NULL);
@ -212,7 +220,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
is_gpt = streq_ptr(pttype, "gpt");
is_mbr = streq_ptr(pttype, "dos");
if (!is_gpt && !is_mbr)
if (!is_gpt && ((flags & DISSECT_IMAGE_GPT_ONLY) || !is_mbr))
return -ENOPKG;
errno = 0;
@ -300,7 +308,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
_cleanup_udev_device_unref_ struct udev_device *q;
unsigned long long flags;
unsigned long long pflags;
blkid_partition pp;
const char *node;
dev_t qn;
@ -325,7 +333,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
if (!pp)
continue;
flags = blkid_partition_get_flags(pp);
pflags = blkid_partition_get_flags(pp);
nr = blkid_partition_get_partno(pp);
if (nr < 0)
@ -337,7 +345,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
sd_id128_t type_id, id;
bool rw = true;
if (flags & GPT_FLAG_NO_AUTO)
if (pflags & GPT_FLAG_NO_AUTO)
continue;
sid = blkid_partition_get_uuid(pp);
@ -354,10 +362,10 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
if (sd_id128_equal(type_id, GPT_HOME)) {
designator = PARTITION_HOME;
rw = !(flags & GPT_FLAG_READ_ONLY);
rw = !(pflags & GPT_FLAG_READ_ONLY);
} else if (sd_id128_equal(type_id, GPT_SRV)) {
designator = PARTITION_SRV;
rw = !(flags & GPT_FLAG_READ_ONLY);
rw = !(pflags & GPT_FLAG_READ_ONLY);
} else if (sd_id128_equal(type_id, GPT_ESP)) {
designator = PARTITION_ESP;
fstype = "vfat";
@ -371,7 +379,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
designator = PARTITION_ROOT;
architecture = native_architecture();
rw = !(flags & GPT_FLAG_READ_ONLY);
rw = !(pflags & GPT_FLAG_READ_ONLY);
} else if (sd_id128_equal(type_id, GPT_ROOT_NATIVE_VERITY)) {
m->can_verity = true;
@ -395,9 +403,8 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
designator = PARTITION_ROOT_SECONDARY;
architecture = SECONDARY_ARCHITECTURE;
rw = !(flags & GPT_FLAG_READ_ONLY);
rw = !(pflags & GPT_FLAG_READ_ONLY);
} else if (sd_id128_equal(type_id, GPT_ROOT_SECONDARY_VERITY)) {
m->can_verity = true;
/* Ignore verity unless root has is specified */
@ -419,7 +426,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
multiple_generic = true;
else {
generic_nr = nr;
generic_rw = !(flags & GPT_FLAG_READ_ONLY);
generic_rw = !(pflags & GPT_FLAG_READ_ONLY);
generic_node = strdup(node);
if (!generic_node)
return -ENOMEM;
@ -457,7 +464,7 @@ int dissect_image(int fd, const void *root_hash, size_t root_hash_size, Dissecte
} else if (is_mbr) {
if (flags != 0x80) /* Bootable flag */
if (pflags != 0x80) /* Bootable flag */
continue;
if (blkid_partition_get_type(pp) != 0x83) /* Linux partition */

3
src/shared/dissect-image.h
View File

@ -67,6 +67,7 @@ typedef enum DissectImageFlags {
DISSECT_IMAGE_DISCARD_ANY = DISSECT_IMAGE_DISCARD_ON_LOOP |
DISSECT_IMAGE_DISCARD |
DISSECT_IMAGE_DISCARD_ON_CRYPTO,
DISSECT_IMAGE_GPT_ONLY = 16, /* Only recognize images with GPT partition tables */
} DissectImageFlags;
struct DissectedImage {
@ -76,7 +77,7 @@ struct DissectedImage {
DissectedPartition partitions[_PARTITION_DESIGNATOR_MAX];
};
int dissect_image(int fd, const void *root_hash, size_t root_hash_size, DissectedImage **ret);
int dissect_image(int fd, const void *root_hash, size_t root_hash_size, DissectImageFlags flags, DissectedImage **ret);
DissectedImage* dissected_image_unref(DissectedImage *m);
DEFINE_TRIVIAL_CLEANUP_FUNC(DissectedImage*, dissected_image_unref);

2
src/test/test-dissect-image.c
View File

@ -43,7 +43,7 @@ int main(int argc, char *argv[]) {
return EXIT_FAILURE;
}
r = dissect_image(d->fd, NULL, 0, &m);
r = dissect_image(d->fd, NULL, 0, 0, &m);
if (r < 0) {
log_error_errno(r, "Failed to dissect image: %m");
return EXIT_FAILURE;