[Libguestfs] [PATCH nbdkit filters-v3 7/7] filters: Add nbdkit-partition-filter.

This can be used to filter a single partition from a disk image. It supports MBR and GPT, but not MBR extended partitions because those are crazy. --- TODO | 2 - configure.ac | 1 + filters/Makefile.am | 3 +- filters/offset/nbdkit-offset-filter.pod | 17 +- filters/partition/Makefile.am | 62 +++++ filters/partition/nbdkit-partition-filter.pod | 99 ++++++++ filters/partition/partition.c | 351 ++++++++++++++++++++++++++ 7 files changed, 531 insertions(+), 4 deletions(-) diff --git a/TODO b/TODO index 3ec45fd..b1f922e 100644 --- a/TODO +++ b/TODO @@ -41,8 +41,6 @@ Suggestions for filters * copy-on-write, a popular feature in other servers -* export a single partition (like qemu-nbd -P) - Composing nbdkit ---------------- diff --git a/configure.ac b/configure.ac index 9376a2e..fd71ca6 100644 --- a/configure.ac +++ b/configure.ac @@ -515,6 +515,7 @@ AC_CONFIG_FILES([Makefile filters/Makefile filters/delay/Makefile filters/offset/Makefile + filters/partition/Makefile src/Makefile src/nbdkit.pc tests/Makefile]) diff --git a/filters/Makefile.am b/filters/Makefile.am index d4aa6c0..d918b81 100644 --- a/filters/Makefile.am +++ b/filters/Makefile.am @@ -32,4 +32,5 @@ SUBDIRS = \ delay \ - offset + offset \ + partition diff --git a/filters/offset/nbdkit-offset-filter.pod b/filters/offset/nbdkit-offset-filter.pod index a94170e..25bdbb9 100644 --- a/filters/offset/nbdkit-offset-filter.pod +++ b/filters/offset/nbdkit-offset-filter.pod @@ -36,7 +36,7 @@ file/device. Note it is an error if the offset and/or range specify data which lies beyond the end of the underlying device. -=head1 EXAMPLE +=head1 EXAMPLES Using L<nbdkit-file-plugin(1)>, serve the file C<disk.img> starting at offset C<1M>. The total length served is C<100M> (the underlying file @@ -44,11 +44,26 @@ must therefore be at least C<101M> in length): nbdkit --filter=offset file file=disk.img offset=1M range=100M +One way to serve a single partition from a disk is to find the start +and length of the partition, eg using: + + $ parted disk.img -- unit b print + ... + Number Start End Size Type File system Flags + 1 65536B 104792575B 104727040B primary ext2 + +You can then serve the partition only using: + + nbdkit --filter=offset file file=disk.img offset=65536 range=104727040 + +An easier way to do this is with L<nbdkit-partition-filter(1)>. + =head1 SEE ALSO L<nbdkit(1)>, L<nbdkit-file-plugin(1)>, L<nbdkit-filter(3)>. +L<nbdkit-partition-filter(1)>. =head1 AUTHORS diff --git a/filters/partition/Makefile.am b/filters/partition/Makefile.am new file mode 100644 index 0000000..0464e7c --- /dev/null +++ b/filters/partition/Makefile.am @@ -0,0 +1,62 @@ +# nbdkit +# Copyright (C) 2018 Red Hat Inc. +# All rights reserved. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * 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. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT 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 RED HAT 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. + +EXTRA_DIST = nbdkit-partition-filter.pod + +CLEANFILES = *~ + +filterdir = $(libdir)/nbdkit/filters + +filter_LTLIBRARIES = nbdkit-partition-filter.la + +nbdkit_partition_filter_la_SOURCES = \ + partition.c \ + $(top_srcdir)/include/nbdkit-filter.h + +nbdkit_partition_filter_la_CPPFLAGS = \ + -I$(top_srcdir)/include +nbdkit_partition_filter_la_CFLAGS = \ + $(WARNINGS_CFLAGS) +nbdkit_partition_filter_la_LDFLAGS = \ + -module -avoid-version -shared + +if HAVE_POD2MAN + +man_MANS = nbdkit-partition-filter.1 +CLEANFILES += $(man_MANS) + +nbdkit-partition-filter.1: nbdkit-partition-filter.pod + $(POD2MAN) $(POD2MAN_ARGS) --section=1 --name=`basename $@ .1` $< $@.t && \ + if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \ + mv $@.t $@ + +endif diff --git a/filters/partition/nbdkit-partition-filter.pod b/filters/partition/nbdkit-partition-filter.pod new file mode 100644 index 0000000..8ba2776 --- /dev/null +++ b/filters/partition/nbdkit-partition-filter.pod @@ -0,0 +1,99 @@ +=encoding utf8 + +=head1 NAME + +nbdkit-partition-filter - nbdkit partition filter + +=head1 SYNOPSIS + + nbdkit --filter=partition plugin partition=PART [plugin-args...] + +=head1 DESCRIPTION + +C<nbdkit-partition-filter> is a filter that limits requests to a +single partition within a disk image that is served by another plugin. + +Partition numbers are specified by the required C<partition> +parameter, and count from 1. + +This works like the C<qemu-nbd -P> option. + +=head1 NOTE + +Only MBR primary partitions and GPT partition tables are supported. +MBR logical partitions are B<not> supported. + +=head1 PARAMETERS + +=over 4 + +=item B<partition=PART> + +The partition number to serve, counting from 1. + +This parameter is required. + +=back + +=head1 EXAMPLE + +F<disk.img> is a partitioned disk image (eg. a virtual machine disk +image). To serve the first partition only use: + + nbdkit --filter=partition file file=disk.img partition=1 + +=head1 SEE ALSO + +L<nbdkit(1)>, +L<nbdkit-file-plugin(1)>, +L<nbdkit-filter(3)>. +L<nbdkit-offset-filter(1)>, +L<parted(8)>. + +=head1 AUTHORS + +Richard W.M. Jones + +=head1 COPYRIGHT + +Copyright (C) 2018 Red Hat Inc. + +=head1 LICENSE + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + +=over 4 + +=item * + +Redistributions of source code must retain the above copyright +notice, this list of conditions and the following disclaimer. + +=item * + +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. + +=item * + +Neither the name of Red Hat nor the names of its contributors may be +used to endorse or promote products derived from this software without +specific prior written permission. + +=back + +THIS SOFTWARE IS PROVIDED BY RED HAT 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 RED HAT 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. diff --git a/filters/partition/partition.c b/filters/partition/partition.c new file mode 100644 index 0000000..ddf6f93 --- /dev/null +++ b/filters/partition/partition.c @@ -0,0 +1,351 @@ +/* nbdkit + * Copyright (C) 2018 Red Hat Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * 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. + * + * * Neither the name of Red Hat nor the names of its contributors may be + * used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY RED HAT 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 RED HAT 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 <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <inttypes.h> +#include <endian.h> + +#include <nbdkit-filter.h> + +static int partnum = -1; + +/* Called for each key=value passed on the command line. */ +static int +partition_config (nbdkit_next_config *next, void *nxdata, + const char *key, const char *value) +{ + if (strcmp (key, "partition") == 0) { + if (sscanf (value, "%d", &partnum) != 1 || partnum <= 0) { + nbdkit_error ("invalid partition number"); + return -1; + } + return 0; + } + else + return next (nxdata, key, value); +} + +/* Check the user did pass partition number. */ +static int +partition_config_complete (nbdkit_next_config_complete *next, void *nxdata) +{ + if (partnum == -1) { + nbdkit_error ("you must supply the partition parameter on the command line"); + return -1; + } + + return next (nxdata); +} + +#define partition_config_help \ + "partition=<PART> (required) The partition number (counting from 1)." + +struct handle { + int64_t offset; + int64_t range; +}; + +/* Open a connection. */ +static void * +partition_open (nbdkit_next_open *next, void *nxdata, int readonly) +{ + struct handle *h; + + if (next (nxdata, readonly) == -1) + return NULL; + + h = malloc (sizeof *h); + if (h == NULL) { + nbdkit_error ("malloc: %m"); + return NULL; + } + + /* These are set in the prepare method. */ + h->offset = h->range = -1; + return h; +} + +static void +partition_close (void *handle) +{ + struct handle *h = handle; + + free (h); +} + +/* Inspect the underlying partition table. partition_prepare is + * called before data processing. + */ +struct mbr_partition { + uint8_t part_type_byte; + uint32_t start_sector; + uint32_t nr_sectors; +}; + +static void +get_mbr_partition (uint8_t *sector, int i, struct mbr_partition *part) +{ + int offset = 0x1BE + i*0x10; + + part->part_type_byte = sector[offset+4]; + memcpy (&part->start_sector, &sector[offset+8], 4); + part->start_sector = le32toh (part->start_sector); + memcpy (&part->nr_sectors, &sector[offset+0xC], 4); + part->nr_sectors = le32toh (part->nr_sectors); +} + +static int +find_mbr_partition (struct nbdkit_next_ops *next_ops, void *nxdata, + struct handle *h, int64_t size, uint8_t *mbr) +{ + int i; + struct mbr_partition partition; + + if (partnum > 4) { + nbdkit_error ("MBR logical partitions are not supported"); + return -1; + } + + for (i = 0; i < 4; ++i) { + get_mbr_partition (mbr, i, &partition); + if (partition.nr_sectors > 0 && + partition.part_type_byte != 0 && + partnum == i+1) { + h->offset = partition.start_sector * 512; + h->range = partition.nr_sectors * 512; + return 0; + } + } + + nbdkit_error ("MBR partition %d not found", partnum); + return -1; +} + +struct gpt_header { + uint32_t nr_partitions; + uint32_t partition_entry_size; +}; + +static void +get_gpt_header (uint8_t *sector, struct gpt_header *header) +{ + memcpy (&header->nr_partitions, &sector[0x50], 4); + header->nr_partitions = le32toh (header->nr_partitions); + memcpy (&header->partition_entry_size, &sector[0x54], 4); + header->partition_entry_size = le32toh (header->partition_entry_size); +} + +struct gpt_partition { + uint8_t partition_type_guid[16]; + uint64_t first_lba; + uint64_t last_lba; +}; + +static void +get_gpt_partition (uint8_t *bytes, struct gpt_partition *part) +{ + memcpy (&part->partition_type_guid, &bytes[0], 16); + memcpy (&part->first_lba, &bytes[0x20], 8); + part->first_lba = le64toh (part->first_lba); + memcpy (&part->last_lba, &bytes[0x28], 8); + part->last_lba = le64toh (part->last_lba); +} + +static int +find_gpt_partition (struct nbdkit_next_ops *next_ops, void *nxdata, + struct handle *h, int64_t size, uint8_t *header_bytes) +{ + uint8_t partition_bytes[128]; + struct gpt_header header; + struct gpt_partition partition; + int i; + + if (partnum > 128) { + out_of_range: + nbdkit_error ("GPT partition number out of range"); + return -1; + } + get_gpt_header (header_bytes, &header); + if (partnum > header.nr_partitions) + goto out_of_range; + + if (header.partition_entry_size != 128) { + nbdkit_error ("GPT partition entry is not 128 bytes"); + return -1; + } + + for (i = 0; i < 128; ++i) { + /* We already checked these are within bounds in the + * partition_prepare call above. + */ + if (next_ops->pread (nxdata, partition_bytes, sizeof partition_bytes, + 2*512 + i*128) == -1) + return -1; + get_gpt_partition (partition_bytes, &partition); + if (memcmp (partition.partition_type_guid, + "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) != 0 && + partnum == i+1) { + h->offset = partition.first_lba * 512; + h->range = (1 + partition.last_lba - partition.first_lba) * 512; + return 0; + } + } + + nbdkit_error ("GPT partition %d not found", partnum); + return -1; +} + +static int +partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle) +{ + struct handle *h = handle; + int64_t size; + uint8_t lba01[1024]; /* LBA 0 and 1 */ + int r; + + size = next_ops->get_size (nxdata); + if (size == -1) + return -1; + if (size < 1024) { + nbdkit_error ("disk is too small to be a partitioned disk"); + return -1; + } + + nbdkit_debug ("disk size=%" PRIi64, size); + + if (next_ops->pread (nxdata, lba01, sizeof lba01, 0) != 0) + return -1; + + /* Is it GPT? */ + if (size >= 2 * 34 * 512 && memcmp (&lba01[512], "EFI PART", 8) == 0) + r = find_gpt_partition (next_ops, nxdata, h, size, &lba01[512]); + /* Is it MBR? */ + else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA) + r = find_mbr_partition (next_ops, nxdata, h, size, lba01); + else { + nbdkit_error ("disk does not contain MBR or GPT partition table signature"); + r = -1; + } + if (r == -1) + return -1; + + /* The find_*_partition functions set h->offset & h->range in the + * handle to point to the partition boundaries. However we + * additionally check that they are inside the underlying disk. + */ + if (h->offset < 0 || h->range < 0 || h->offset + h->range > size) { + nbdkit_error ("partition is outside the disk"); + return -1; + } + + nbdkit_debug ("partition offset=%" PRIi64 " range=%" PRIi64, + h->offset, h->range); + + return 0; +} + +/* Get the file size. */ +static int64_t +partition_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle) +{ + struct handle *h = handle; + + return h->range; +} + +/* Read data. */ +static int +partition_pread (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle, void *buf, uint32_t count, uint64_t offs) +{ + struct handle *h = handle; + + return next_ops->pread (nxdata, buf, count, offs + h->offset); +} + +/* Write data. */ +static int +partition_pwrite (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle, + const void *buf, uint32_t count, uint64_t offs) +{ + struct handle *h = handle; + + return next_ops->pwrite (nxdata, buf, count, offs + h->offset); +} + +/* Trim data. */ +static int +partition_trim (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle, uint32_t count, uint64_t offs) +{ + struct handle *h = handle; + + return next_ops->trim (nxdata, count, offs + h->offset); +} + +/* Zero data. */ +static int +partition_zero (struct nbdkit_next_ops *next_ops, void *nxdata, + void *handle, uint32_t count, uint64_t offs, int may_trim) +{ + struct handle *h = handle; + + return next_ops->zero (nxdata, count, offs + h->offset, may_trim); +} + +static struct nbdkit_filter filter = { + .name = "partition", + .longname = "nbdkit partition filter", + .version = PACKAGE_VERSION, + .config = partition_config, + .config_complete = partition_config_complete, + .config_help = partition_config_help, + .open = partition_open, + .prepare = partition_prepare, + .close = partition_close, + .get_size = partition_get_size, + .pread = partition_pread, + .pwrite = partition_pwrite, + .trim = partition_trim, + .zero = partition_zero, +}; + +NBDKIT_REGISTER_FILTER(filter) -- 2.15.1