5:03 p.m.
Applies on top of my pending series for the exportname filter,
addressing one of the todo's in that cover letter.
Eric Blake (2):
filters: Add .export_description wrappers
ext2: Supply .list_exports and .default_export
filters/ext2/nbdkit-ext2-filter.pod | 3 +-
tests/Makefile.am | 16 +++-
filters/ext2/ext2.c | 125 +++++++++++++++++++---------
filters/gzip/gzip.c | 40 ++++++---
filters/partition/partition.c | 58 +++++++++----
filters/tar/tar.c | 48 +++++++----
filters/xz/xz.c | 43 +++++++---
tests/test-ext2-exportname.sh | 73 ++++++++++++++++
8 files changed, 305 insertions(+), 101 deletions(-)
create mode 100755 tests/test-ext2-exportname.sh
--
2.28.0
5:03 p.m.
New subject: [nbdkit PATCH 1/2] filters: Add .export_description wrappers
When extracting an obvious subset of a larger container (ext2, gzip,
partition, tar, xz), it's fairly easy to add a nice updated
description for what the client is seeing. Not all clients request
the description, but if you are worried about this leaking too much
information, it can be silenced with nbdkit-exportname-filter.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
And maybe this is an excuse for adding nbdkit_[v]printf_intern()...
---
filters/ext2/ext2.c | 54 ++++++++++++++++++++++----------
filters/gzip/gzip.c | 40 ++++++++++++++++--------
filters/partition/partition.c | 58 +++++++++++++++++++++++++----------
filters/tar/tar.c | 48 +++++++++++++++++++----------
filters/xz/xz.c | 43 ++++++++++++++++++--------
5 files changed, 168 insertions(+), 75 deletions(-)
diff --git a/filters/ext2/ext2.c b/filters/ext2/ext2.c
index 75ac2c4c..7ad4a005 100644
--- a/filters/ext2/ext2.c
+++ b/filters/ext2/ext2.c
@@ -294,6 +294,25 @@ static int ext2_thread_model (void)
return NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS;
}
+/* Description. */
+static const char *
+ext2_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *fname = file ?: h->exportname;
+ const char *slash = fname[0] == '/' ? "" : "/";
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base)
+ asprintf (&desc, "embedded '%s%s' from within ext2 image: %s",
+ slash, fname, base);
+ else
+ asprintf (&desc, "embedded '%s%s' from within ext2 image",
slash, fname);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the disk size. */
static int64_t
ext2_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -412,23 +431,24 @@ ext2_flush (struct nbdkit_next_ops *next_ops, void *nxdata,
*/
static struct nbdkit_filter filter = {
- .name = "ext2",
- .longname = "nbdkit ext2 filter",
- .load = ext2_load,
- .unload = ext2_unload,
- .config = ext2_config,
- .config_complete = ext2_config_complete,
- .config_help = ext2_config_help,
- .thread_model = ext2_thread_model,
- .open = ext2_open,
- .prepare = ext2_prepare,
- .close = ext2_close,
- .can_fua = ext2_can_fua,
- .can_cache = ext2_can_cache,
- .get_size = ext2_get_size,
- .pread = ext2_pread,
- .pwrite = ext2_pwrite,
- .flush = ext2_flush,
+ .name = "ext2",
+ .longname = "nbdkit ext2 filter",
+ .load = ext2_load,
+ .unload = ext2_unload,
+ .config = ext2_config,
+ .config_complete = ext2_config_complete,
+ .config_help = ext2_config_help,
+ .thread_model = ext2_thread_model,
+ .open = ext2_open,
+ .prepare = ext2_prepare,
+ .close = ext2_close,
+ .can_fua = ext2_can_fua,
+ .can_cache = ext2_can_cache,
+ .export_description = ext2_export_description,
+ .get_size = ext2_get_size,
+ .pread = ext2_pread,
+ .pwrite = ext2_pwrite,
+ .flush = ext2_flush,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/gzip/gzip.c b/filters/gzip/gzip.c
index 929260bf..833ea937 100644
--- a/filters/gzip/gzip.c
+++ b/filters/gzip/gzip.c
@@ -287,6 +287,21 @@ gzip_can_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
return NBDKIT_CACHE_EMULATE;
}
+/* Description. */
+static const char *
+gzip_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base) {
+ asprintf (&desc, "expansion of gzip-compressed image: %s", base);
+ return nbdkit_strdup_intern (desc);
+ }
+ return "expansion of gzip-compressed image";
+}
+
/* Get the file size. */
static int64_t
gzip_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -339,18 +354,19 @@ gzip_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "gzip",
- .longname = "nbdkit gzip filter",
- .unload = gzip_unload,
- .thread_model = gzip_thread_model,
- .open = gzip_open,
- .prepare = gzip_prepare,
- .can_write = gzip_can_write,
- .can_extents = gzip_can_extents,
- .can_cache = gzip_can_cache,
- .prepare = gzip_prepare,
- .get_size = gzip_get_size,
- .pread = gzip_pread,
+ .name = "gzip",
+ .longname = "nbdkit gzip filter",
+ .unload = gzip_unload,
+ .thread_model = gzip_thread_model,
+ .open = gzip_open,
+ .prepare = gzip_prepare,
+ .can_write = gzip_can_write,
+ .can_extents = gzip_can_extents,
+ .can_cache = gzip_can_cache,
+ .prepare = gzip_prepare,
+ .export_description = gzip_export_description,
+ .get_size = gzip_get_size,
+ .pread = gzip_pread,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/partition/partition.c b/filters/partition/partition.c
index 849f0cc7..bb83da7b 100644
--- a/filters/partition/partition.c
+++ b/filters/partition/partition.c
@@ -37,6 +37,7 @@
#include <stdint.h>
#include <string.h>
#include <inttypes.h>
+#include <assert.h>
#include <nbdkit-filter.h>
@@ -83,6 +84,7 @@ partition_config_complete (nbdkit_next_config_complete *next, void
*nxdata)
struct handle {
int64_t offset;
int64_t range;
+ const char *type;
};
/* Open a connection. */
@@ -139,13 +141,17 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
/* Is it GPT? */
if (size >= 2 * 34 * SECTOR_SIZE &&
- memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0)
+ memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0) {
r = find_gpt_partition (next_ops, nxdata, size, &lba01[SECTOR_SIZE],
&h->offset, &h->range);
+ h->type = "GPT";
+ }
/* Is it MBR? */
- else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA)
+ else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA) {
r = find_mbr_partition (next_ops, nxdata, size, lba01,
&h->offset, &h->range);
+ h->type = "MBR";
+ }
else {
nbdkit_error ("disk does not contain MBR or GPT partition table
signature");
r = -1;
@@ -168,6 +174,23 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+partition_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ assert (h->type);
+ if (base)
+ asprintf (&desc, "partition %d of %s disk: %s", partnum, h->type,
base);
+ else
+ asprintf (&desc, "partition %d of %s disk", partnum, h->type);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the file size. */
static int64_t
partition_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -266,21 +289,22 @@ partition_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "partition",
- .longname = "nbdkit partition filter",
- .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,
- .extents = partition_extents,
- .cache = partition_cache,
+ .name = "partition",
+ .longname = "nbdkit partition filter",
+ .config = partition_config,
+ .config_complete = partition_config_complete,
+ .config_help = partition_config_help,
+ .open = partition_open,
+ .prepare = partition_prepare,
+ .close = partition_close,
+ .export_description = partition_export_description,
+ .get_size = partition_get_size,
+ .pread = partition_pread,
+ .pwrite = partition_pwrite,
+ .trim = partition_trim,
+ .zero = partition_zero,
+ .extents = partition_extents,
+ .cache = partition_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/tar/tar.c b/filters/tar/tar.c
index cb42b918..090a2144 100644
--- a/filters/tar/tar.c
+++ b/filters/tar/tar.c
@@ -295,6 +295,21 @@ tar_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+tar_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base)
+ asprintf (&desc, "embedded %s from within tar file: %s", entry, base);
+ else
+ asprintf (&desc, "embedded %s from within tar file", entry);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the file size. */
static int64_t
tar_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -395,22 +410,23 @@ tar_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "tar",
- .longname = "nbdkit tar filter",
- .config = tar_config,
- .config_complete = tar_config_complete,
- .config_help = tar_config_help,
- .thread_model = tar_thread_model,
- .open = tar_open,
- .close = tar_close,
- .prepare = tar_prepare,
- .get_size = tar_get_size,
- .pread = tar_pread,
- .pwrite = tar_pwrite,
- .trim = tar_trim,
- .zero = tar_zero,
- .extents = tar_extents,
- .cache = tar_cache,
+ .name = "tar",
+ .longname = "nbdkit tar filter",
+ .config = tar_config,
+ .config_complete = tar_config_complete,
+ .config_help = tar_config_help,
+ .thread_model = tar_thread_model,
+ .open = tar_open,
+ .close = tar_close,
+ .prepare = tar_prepare,
+ .export_description = tar_export_description,
+ .get_size = tar_get_size,
+ .pread = tar_pread,
+ .pwrite = tar_pwrite,
+ .trim = tar_trim,
+ .zero = tar_zero,
+ .extents = tar_extents,
+ .cache = tar_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/xz/xz.c b/filters/xz/xz.c
index 26cfa959..2aa8c893 100644
--- a/filters/xz/xz.c
+++ b/filters/xz/xz.c
@@ -47,6 +47,7 @@
#include "xzfile.h"
#include "blkcache.h"
+#include "cleanup.h"
static uint64_t maxblock = 512 * 1024 * 1024;
static uint32_t maxdepth = 8;
@@ -156,6 +157,21 @@ xz_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, void
*handle,
return 0;
}
+/* Description. */
+static const char *
+xz_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base) {
+ asprintf (&desc, "expansion of xz-compressed image: %s", base);
+ return nbdkit_strdup_intern (desc);
+ }
+ return "expansion of xz-compressed image";
+}
+
/* Get the file size. */
static int64_t
xz_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -245,19 +261,20 @@ static int xz_thread_model (void)
}
static struct nbdkit_filter filter = {
- .name = "xz",
- .longname = "nbdkit XZ filter",
- .config = xz_config,
- .config_help = xz_config_help,
- .thread_model = xz_thread_model,
- .open = xz_open,
- .close = xz_close,
- .prepare = xz_prepare,
- .get_size = xz_get_size,
- .can_write = xz_can_write,
- .can_extents = xz_can_extents,
- .can_cache = xz_can_cache,
- .pread = xz_pread,
+ .name = "xz",
+ .longname = "nbdkit XZ filter",
+ .config = xz_config,
+ .config_help = xz_config_help,
+ .thread_model = xz_thread_model,
+ .open = xz_open,
+ .close = xz_close,
+ .prepare = xz_prepare,
+ .export_description = xz_export_description,
+ .get_size = xz_get_size,
+ .can_write = xz_can_write,
+ .can_extents = xz_can_extents,
+ .can_cache = xz_can_cache,
+ .pread = xz_pread,
};
NBDKIT_REGISTER_FILTER(filter)
--
2.28.0
9:30 a.m.
New subject: [nbdkit PATCH 1/2] filters: Add .export_description wrappers
On Thu, Aug 27, 2020 at 05:03:45PM -0500, Eric Blake wrote:
When extracting an obvious subset of a larger container (ext2, gzip,
partition, tar, xz), it's fairly easy to add a nice updated
description for what the client is seeing. Not all clients request
the description, but if you are worried about this leaking too much
information, it can be silenced with nbdkit-exportname-filter.
No?
The trouble with this is it leaks configuration information of the
server which most users of nbdkit would not really be aware of. NBD
protocol export descriptions are a pretty obscure thing - even I would
have to look at the qemu-nbd manual to work out how to read them from
an NBD server.
Also I don't really see the benefit of this to anyone. The server
admin already knows this, and the client doesn't care unless they're
looking for a way to attack the server.
And maybe this is an excuse for adding nbdkit_[v]printf_intern()...
This could well be useful.
Rich.
filters/ext2/ext2.c | 54 ++++++++++++++++++++++----------
filters/gzip/gzip.c | 40 ++++++++++++++++--------
filters/partition/partition.c | 58 +++++++++++++++++++++++++----------
filters/tar/tar.c | 48 +++++++++++++++++++----------
filters/xz/xz.c | 43 ++++++++++++++++++--------
5 files changed, 168 insertions(+), 75 deletions(-)
diff --git a/filters/ext2/ext2.c b/filters/ext2/ext2.c
index 75ac2c4c..7ad4a005 100644
--- a/filters/ext2/ext2.c
+++ b/filters/ext2/ext2.c
@@ -294,6 +294,25 @@ static int ext2_thread_model (void)
return NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS;
}
+/* Description. */
+static const char *
+ext2_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *fname = file ?: h->exportname;
+ const char *slash = fname[0] == '/' ? "" : "/";
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base)
+ asprintf (&desc, "embedded '%s%s' from within ext2 image:
%s",
+ slash, fname, base);
+ else
+ asprintf (&desc, "embedded '%s%s' from within ext2 image",
slash, fname);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the disk size. */
static int64_t
ext2_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -412,23 +431,24 @@ ext2_flush (struct nbdkit_next_ops *next_ops, void *nxdata,
*/
static struct nbdkit_filter filter = {
- .name = "ext2",
- .longname = "nbdkit ext2 filter",
- .load = ext2_load,
- .unload = ext2_unload,
- .config = ext2_config,
- .config_complete = ext2_config_complete,
- .config_help = ext2_config_help,
- .thread_model = ext2_thread_model,
- .open = ext2_open,
- .prepare = ext2_prepare,
- .close = ext2_close,
- .can_fua = ext2_can_fua,
- .can_cache = ext2_can_cache,
- .get_size = ext2_get_size,
- .pread = ext2_pread,
- .pwrite = ext2_pwrite,
- .flush = ext2_flush,
+ .name = "ext2",
+ .longname = "nbdkit ext2 filter",
+ .load = ext2_load,
+ .unload = ext2_unload,
+ .config = ext2_config,
+ .config_complete = ext2_config_complete,
+ .config_help = ext2_config_help,
+ .thread_model = ext2_thread_model,
+ .open = ext2_open,
+ .prepare = ext2_prepare,
+ .close = ext2_close,
+ .can_fua = ext2_can_fua,
+ .can_cache = ext2_can_cache,
+ .export_description = ext2_export_description,
+ .get_size = ext2_get_size,
+ .pread = ext2_pread,
+ .pwrite = ext2_pwrite,
+ .flush = ext2_flush,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/gzip/gzip.c b/filters/gzip/gzip.c
index 929260bf..833ea937 100644
--- a/filters/gzip/gzip.c
+++ b/filters/gzip/gzip.c
@@ -287,6 +287,21 @@ gzip_can_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
return NBDKIT_CACHE_EMULATE;
}
+/* Description. */
+static const char *
+gzip_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base) {
+ asprintf (&desc, "expansion of gzip-compressed image: %s", base);
+ return nbdkit_strdup_intern (desc);
+ }
+ return "expansion of gzip-compressed image";
+}
+
/* Get the file size. */
static int64_t
gzip_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -339,18 +354,19 @@ gzip_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "gzip",
- .longname = "nbdkit gzip filter",
- .unload = gzip_unload,
- .thread_model = gzip_thread_model,
- .open = gzip_open,
- .prepare = gzip_prepare,
- .can_write = gzip_can_write,
- .can_extents = gzip_can_extents,
- .can_cache = gzip_can_cache,
- .prepare = gzip_prepare,
- .get_size = gzip_get_size,
- .pread = gzip_pread,
+ .name = "gzip",
+ .longname = "nbdkit gzip filter",
+ .unload = gzip_unload,
+ .thread_model = gzip_thread_model,
+ .open = gzip_open,
+ .prepare = gzip_prepare,
+ .can_write = gzip_can_write,
+ .can_extents = gzip_can_extents,
+ .can_cache = gzip_can_cache,
+ .prepare = gzip_prepare,
+ .export_description = gzip_export_description,
+ .get_size = gzip_get_size,
+ .pread = gzip_pread,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/partition/partition.c b/filters/partition/partition.c
index 849f0cc7..bb83da7b 100644
--- a/filters/partition/partition.c
+++ b/filters/partition/partition.c
@@ -37,6 +37,7 @@
#include <stdint.h>
#include <string.h>
#include <inttypes.h>
+#include <assert.h>
#include <nbdkit-filter.h>
@@ -83,6 +84,7 @@ partition_config_complete (nbdkit_next_config_complete *next, void
*nxdata)
struct handle {
int64_t offset;
int64_t range;
+ const char *type;
};
/* Open a connection. */
@@ -139,13 +141,17 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
/* Is it GPT? */
if (size >= 2 * 34 * SECTOR_SIZE &&
- memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0)
+ memcmp (&lba01[SECTOR_SIZE], "EFI PART", 8) == 0) {
r = find_gpt_partition (next_ops, nxdata, size, &lba01[SECTOR_SIZE],
&h->offset, &h->range);
+ h->type = "GPT";
+ }
/* Is it MBR? */
- else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA)
+ else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA) {
r = find_mbr_partition (next_ops, nxdata, size, lba01,
&h->offset, &h->range);
+ h->type = "MBR";
+ }
else {
nbdkit_error ("disk does not contain MBR or GPT partition table
signature");
r = -1;
@@ -168,6 +174,23 @@ partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+partition_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ assert (h->type);
+ if (base)
+ asprintf (&desc, "partition %d of %s disk: %s", partnum, h->type,
base);
+ else
+ asprintf (&desc, "partition %d of %s disk", partnum, h->type);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the file size. */
static int64_t
partition_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -266,21 +289,22 @@ partition_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "partition",
- .longname = "nbdkit partition filter",
- .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,
- .extents = partition_extents,
- .cache = partition_cache,
+ .name = "partition",
+ .longname = "nbdkit partition filter",
+ .config = partition_config,
+ .config_complete = partition_config_complete,
+ .config_help = partition_config_help,
+ .open = partition_open,
+ .prepare = partition_prepare,
+ .close = partition_close,
+ .export_description = partition_export_description,
+ .get_size = partition_get_size,
+ .pread = partition_pread,
+ .pwrite = partition_pwrite,
+ .trim = partition_trim,
+ .zero = partition_zero,
+ .extents = partition_extents,
+ .cache = partition_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/tar/tar.c b/filters/tar/tar.c
index cb42b918..090a2144 100644
--- a/filters/tar/tar.c
+++ b/filters/tar/tar.c
@@ -295,6 +295,21 @@ tar_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
return 0;
}
+/* Description. */
+static const char *
+tar_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base)
+ asprintf (&desc, "embedded %s from within tar file: %s", entry,
base);
+ else
+ asprintf (&desc, "embedded %s from within tar file", entry);
+ return nbdkit_strdup_intern (desc);
+}
+
/* Get the file size. */
static int64_t
tar_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
@@ -395,22 +410,23 @@ tar_cache (struct nbdkit_next_ops *next_ops, void *nxdata,
}
static struct nbdkit_filter filter = {
- .name = "tar",
- .longname = "nbdkit tar filter",
- .config = tar_config,
- .config_complete = tar_config_complete,
- .config_help = tar_config_help,
- .thread_model = tar_thread_model,
- .open = tar_open,
- .close = tar_close,
- .prepare = tar_prepare,
- .get_size = tar_get_size,
- .pread = tar_pread,
- .pwrite = tar_pwrite,
- .trim = tar_trim,
- .zero = tar_zero,
- .extents = tar_extents,
- .cache = tar_cache,
+ .name = "tar",
+ .longname = "nbdkit tar filter",
+ .config = tar_config,
+ .config_complete = tar_config_complete,
+ .config_help = tar_config_help,
+ .thread_model = tar_thread_model,
+ .open = tar_open,
+ .close = tar_close,
+ .prepare = tar_prepare,
+ .export_description = tar_export_description,
+ .get_size = tar_get_size,
+ .pread = tar_pread,
+ .pwrite = tar_pwrite,
+ .trim = tar_trim,
+ .zero = tar_zero,
+ .extents = tar_extents,
+ .cache = tar_cache,
};
NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/xz/xz.c b/filters/xz/xz.c
index 26cfa959..2aa8c893 100644
--- a/filters/xz/xz.c
+++ b/filters/xz/xz.c
@@ -47,6 +47,7 @@
#include "xzfile.h"
#include "blkcache.h"
+#include "cleanup.h"
static uint64_t maxblock = 512 * 1024 * 1024;
static uint32_t maxdepth = 8;
@@ -156,6 +157,21 @@ xz_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, void
*handle,
return 0;
}
+/* Description. */
+static const char *
+xz_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ const char *base = next_ops->export_description (nxdata);
+ CLEANUP_FREE char *desc = NULL;
+
+ if (base) {
+ asprintf (&desc, "expansion of xz-compressed image: %s", base);
+ return nbdkit_strdup_intern (desc);
+ }
+ return "expansion of xz-compressed image";
+}
+
/* Get the file size. */
static int64_t
xz_get_size (struct nbdkit_next_ops *next_ops, void *nxdata, void *handle)
@@ -245,19 +261,20 @@ static int xz_thread_model (void)
}
static struct nbdkit_filter filter = {
- .name = "xz",
- .longname = "nbdkit XZ filter",
- .config = xz_config,
- .config_help = xz_config_help,
- .thread_model = xz_thread_model,
- .open = xz_open,
- .close = xz_close,
- .prepare = xz_prepare,
- .get_size = xz_get_size,
- .can_write = xz_can_write,
- .can_extents = xz_can_extents,
- .can_cache = xz_can_cache,
- .pread = xz_pread,
+ .name = "xz",
+ .longname = "nbdkit XZ filter",
+ .config = xz_config,
+ .config_help = xz_config_help,
+ .thread_model = xz_thread_model,
+ .open = xz_open,
+ .close = xz_close,
+ .prepare = xz_prepare,
+ .export_description = xz_export_description,
+ .get_size = xz_get_size,
+ .can_write = xz_can_write,
+ .can_extents = xz_can_extents,
+ .can_cache = xz_can_cache,
+ .pread = xz_pread,
};
NBDKIT_REGISTER_FILTER(filter)
--
2.28.0
_______________________________________________
Libguestfs mailing list
Libguestfs(a)redhat.com
https://www.redhat.com/mailman/listinfo/libguestfs
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
Fedora Windows cross-compiler. Compile Windows programs, test, and
build Windows installers. Over 100 libraries supported.
http://fedoraproject.org/wiki/MinGW
1:43 p.m.
New subject: [nbdkit PATCH 1/2] filters: Add .export_description wrappers
On 9/1/20 9:30 AM, Richard W.M. Jones wrote:
On Thu, Aug 27, 2020 at 05:03:45PM -0500, Eric Blake wrote:
> When extracting an obvious subset of a larger container (ext2, gzip,
> partition, tar, xz), it's fairly easy to add a nice updated
> description for what the client is seeing. Not all clients request
> the description, but if you are worried about this leaking too much
> information, it can be silenced with nbdkit-exportname-filter.
No?
The trouble with this is it leaks configuration information of the
server which most users of nbdkit would not really be aware of. NBD
protocol export descriptions are a pretty obscure thing - even I would
have to look at the qemu-nbd manual to work out how to read them from
an NBD server.
Also I don't really see the benefit of this to anyone. The server
admin already knows this, and the client doesn't care unless they're
looking for a way to attack the server.
Okay, that's worth thinking about. A server is unlikely to need to
provide descriptions when it serves the same content to everyone; it is
more a useful tactic to servers that offer multiple exports, and wants
to aid the client in making that choice. For example, when using 'file
dir=/path/to/nbdkit', we could advertise:
"aclocal.m4", "-rw-rw-r--. 1 eblake eblake 54764 Sep 1 11:03
aclocal.m4"
"BENCHMARKING", "-rw-rw-r--. 1 eblake eblake 5324 Aug 19 08:46
BENCHMARKING"
...
Now, if we wrap the ext2 filter in front of that, either:
ext2 is hardcoded to extracting a specific filename from the underlying
image, but the client is choosing which image to extract it from (seeing
the original description is now a bit off, because we are now exposing
only a subset of the file),
or ext2 is honoring export names directly, and calling next_open(""), in
which case the description of the default export in the file plugin
makes even less sense.
The simplest course of action is to just have the ext2 filter always
advertise NULL as the description (any description from the plugin is
lost, because by the time we extract a file from an ext2 image, the
original image's description is no longer fully applicable to the subset
we are exposing). Or maybe we could do:
if plugin reports NULL, we also report NULL
if plugin reports string, we prefix a hint that we are extracting an
ext2 file out of the plugin's description string
> And maybe this is an excuse for adding nbdkit_[v]printf_intern()...
This could well be useful.
That part is now done.
> +/* Description. */
> +static const char *
> +ext2_export_description (struct nbdkit_next_ops *next_ops, void *nxdata,
> + void *handle)
> +{
> + struct handle *h = handle;
> + const char *fname = file ?: h->exportname;
> + const char *slash = fname[0] == '/' ? "" : "/";
> + const char *base = next_ops->export_description (nxdata);
> + CLEANUP_FREE char *desc = NULL;
> +
> + if (base)
> + asprintf (&desc, "embedded '%s%s' from within ext2 image:
%s",
> + slash, fname, base);
This is the case where a prefix might be nice...
> + else
> + asprintf (&desc, "embedded '%s%s' from within ext2 image",
slash, fname);
...where this is a case where since the original plugin had no
description, we are better off not providing one ourselves, either.
But you are also right that providing a prefix is somewhat redundant -
the person that invoked nbdkit to set up the server already knows what
is being served, and the client is less likely to care about the
description of what is being served, compared to the actual content.
So like you, I'm now wavering on whether we actually want this patch, or
one that just provides an .export_description that always returns NULL,
or something else.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
5:03 p.m.
New subject: [nbdkit PATCH 2/2] ext2: Supply .list_exports and .default_export
When using ext2file=exportname to pick the file to server from the
client's export name, we do not want to leak the underlying plugin's
export list. While touching this, take advantage of string lifetimes
via nbdkit_strdup_intern and similar for less cleanup bookkeeping.
Note that we don't actually implement a full .list_exports; doing that
with NBD_OPT_LIST is likely prohibitive (it's likely the disk contains
LOTS of files), and would require that we can do next_ops->pread prior
to the client reaching our .open. For the former issue, it would be
better if the NBD protocol adds a new option NBD_OPT_LIST_HIER that
has replies that differentiate between containers and leaves, and only
lists elements within a container supplied as an argument. For the
latter, we already know we want to tweak filters to be able to open a
plugin independently of a client's connection. And for now we punt,
and leave the advertised list empty.
It's also high time we had some testsuite coverage of
ext2file=exportname. Although ext2.img doesn't technically depend on
the new test, including the dependency ensures the file gets rebuilt
in an incremental build.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
filters/ext2/nbdkit-ext2-filter.pod | 3 +-
tests/Makefile.am | 16 +++++--
filters/ext2/ext2.c | 73 ++++++++++++++++++++---------
tests/test-ext2-exportname.sh | 73 +++++++++++++++++++++++++++++
4 files changed, 138 insertions(+), 27 deletions(-)
create mode 100755 tests/test-ext2-exportname.sh
diff --git a/filters/ext2/nbdkit-ext2-filter.pod b/filters/ext2/nbdkit-ext2-filter.pod
index 1aef9c2e..c15a2fcb 100644
--- a/filters/ext2/nbdkit-ext2-filter.pod
+++ b/filters/ext2/nbdkit-ext2-filter.pod
@@ -67,7 +67,8 @@ a security risk in some situations.
At present, when using this mode, the server does not advertise any
particular exports; however, you may use
-L<nbdkit-exportname-filter(1)> to perform that task.
+L<nbdkit-exportname-filter(1)> to perform that task. Similarly, the
+underlying plugin must support the default export name, C<"">.
=back
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8a799ccf..911fa2b3 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1373,23 +1373,31 @@ EXTRA_DIST += test-exportname.sh
# ext2 filter test.
if HAVE_MKE2FS_WITH_D
if HAVE_EXT2
-if HAVE_GUESTFISH
-LIBGUESTFS_TESTS += test-ext2
+TESTS += test-ext2-exportname.sh
+EXTRA_DIST += test-ext2-exportname.sh
+
check_DATA += ext2.img
CLEANFILES += ext2.img
-ext2.img: disk
+ext2.img: disk test-ext2-exportname.sh
rm -f $@ $@-t
+ echo /disks/disk.img > manifest
guestfish \
sparse $@-t 2G : \
run : \
mkfs ext4 /dev/sda : \
mount /dev/sda / : \
mkdir /disks : \
- upload $< /disks/disk.img
+ upload $< /disks/disk.img : \
+ upload manifest /manifest
+ rm manifest
mv $@-t $@
+if HAVE_GUESTFISH
+
+LIBGUESTFS_TESTS += test-ext2
+
test_ext2_SOURCES = test-ext2.c test.h
test_ext2_CFLAGS = $(WARNINGS_CFLAGS) $(LIBGUESTFS_CFLAGS)
test_ext2_LDADD = libtest.la $(LIBGUESTFS_LIBS)
diff --git a/filters/ext2/ext2.c b/filters/ext2/ext2.c
index 7ad4a005..cfc03a3c 100644
--- a/filters/ext2/ext2.c
+++ b/filters/ext2/ext2.c
@@ -50,8 +50,10 @@
#include "cleanup.h"
#include "io.h"
-/* Filename parameter, or NULL to honor export name. */
-static char *file;
+/* Filename parameter, or NULL to honor export name. Using the export
+ * name is opt-in (see ext2_config_complete).
+ */
+static const char *file;
static void
ext2_load (void)
@@ -59,12 +61,6 @@ ext2_load (void)
initialize_ext2_error_table ();
}
-static void
-ext2_unload (void)
-{
- free (file);
-}
-
static int
ext2_config (nbdkit_next_config *next, void *nxdata,
const char *key, const char *value)
@@ -74,11 +70,7 @@ ext2_config (nbdkit_next_config *next, void *nxdata,
nbdkit_error ("ext2file parameter specified more than once");
return -1;
}
- file = strdup (value);
- if (file == NULL) {
- nbdkit_error ("strdup: %m");
- return -1;
- }
+ file = value;
return 0;
}
else
@@ -94,10 +86,8 @@ ext2_config_complete (nbdkit_next_config_complete *next, void *nxdata)
return -1;
}
- if (strcmp (file, "exportname") == 0) {
- free (file);
+ if (strcmp (file, "exportname") == 0)
file = NULL;
- }
else if (file[0] != '/') {
nbdkit_error ("the file parameter must refer to an absolute path");
return -1;
@@ -112,13 +102,54 @@ ext2_config_complete (nbdkit_next_config_complete *next, void
*nxdata)
/* The per-connection handle. */
struct handle {
- char *exportname; /* Client export name. */
+ const char *exportname; /* Client export name. */
ext2_filsys fs; /* Filesystem handle. */
ext2_ino_t ino; /* Inode of open file. */
ext2_file_t file; /* File handle. */
struct nbdkit_next next; /* "name" parameter to ext2fs_open. */
};
+/* Export list. */
+static int
+ext2_list_exports (nbdkit_next_list_exports *next, void *nxdata,
+ int readonly, int is_tls, struct nbdkit_exports *exports)
+{
+ /* If we are honoring export names, the default export "" won't
+ * work, and we must not leak export names from the underlying
+ * plugin. Advertising all filenames within the ext2 image could be
+ * huge, and even if we wanted to, it would require that we could
+ * open the plugin prior to the client reaching our .open. So leave
+ * the list empty instead.
+ */
+ if (!file)
+ return 0;
+
+ /* If we are serving a specific ext2file, we don't care what export
+ * name the user passes, but the underlying plugin might; there's no
+ * harm in advertising that list.
+ */
+ return next (nxdata, readonly, exports);
+}
+
+/* Default export. */
+static const char *
+ext2_default_export (nbdkit_next_default_export *next, void *nxdata,
+ int readonly, int is_tls)
+{
+ /* If we are honoring exports, "" will fail (even if we resolve to
+ * the inode of embedded "/", we can't serve directories), and we
+ * don't really have a sane default. XXX picking the largest
+ * embedded file might be in interesting knob to add.
+ */
+ if (file)
+ return NULL;
+
+ /* Otherwise, we don't care about export name, so keeping things at
+ * "" is fine, regardless of the underlying plugin's default.
+ */
+ return "";
+}
+
/* Create the per-connection handle. */
static void *
ext2_open (nbdkit_next_open *next, void *nxdata,
@@ -133,9 +164,8 @@ ext2_open (nbdkit_next_open *next, void *nxdata,
}
/* Save the client exportname in the handle. */
- h->exportname = strdup (exportname);
+ h->exportname = nbdkit_strdup_intern (exportname);
if (h->exportname == NULL) {
- nbdkit_error ("strdup: %m");
free (h);
return NULL;
}
@@ -147,7 +177,6 @@ ext2_open (nbdkit_next_open *next, void *nxdata,
/* Request write access to the underlying plugin, for journal replay. */
if (next (nxdata, 0, exportname) == -1) {
- free (h->exportname);
free (h);
return NULL;
}
@@ -260,7 +289,6 @@ ext2_close (void *handle)
ext2fs_file_close (h->file);
ext2fs_close (h->fs);
}
- free (h->exportname);
free (h);
}
@@ -434,11 +462,12 @@ static struct nbdkit_filter filter = {
.name = "ext2",
.longname = "nbdkit ext2 filter",
.load = ext2_load,
- .unload = ext2_unload,
.config = ext2_config,
.config_complete = ext2_config_complete,
.config_help = ext2_config_help,
.thread_model = ext2_thread_model,
+ .list_exports = ext2_list_exports,
+ .default_export = ext2_default_export,
.open = ext2_open,
.prepare = ext2_prepare,
.close = ext2_close,
diff --git a/tests/test-ext2-exportname.sh b/tests/test-ext2-exportname.sh
new file mode 100755
index 00000000..b30aa870
--- /dev/null
+++ b/tests/test-ext2-exportname.sh
@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+# nbdkit
+# Copyright (C) 2019-2020 Red Hat Inc.
+#
+# 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.
+
+source ./functions.sh
+set -e
+set -x
+
+requires_plugin file
+requires nbdinfo --version
+requires nbdsh -c 'print (h.set_full_info)'
+
+sock=`mktemp -u`
+files="$sock ext2-exportname.pid ext2-exportname.out"
+rm -f $files
+cleanup_fn rm -f $files
+
+# Set up a long-running server responsive to the client's export name
+start_nbdkit -P ext2-exportname.pid -U $sock --filter=ext2 \
+ --filter=exportname file ext2.img ext2file=exportname \
+ exportname-list=explicit exportname=hidden
+
+# Test that when serving by exportname, our description varies according
+# to the client's request.
+nbdinfo nbd+unix:///manifest\?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep manifest ext2-exportname.out
+grep 'content.*ASCII' ext2-exportname.out
+
+nbdinfo nbd+unix:///disks/disk.img\?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep disk.img ext2-exportname.out
+grep 'content.*MBR' ext2-exportname.out
+
+if nbdinfo nbd+unix://?socket=$sock > ext2-exportname.out; then
+ echo "unexpected success"
+ exit 1
+fi
+
+# Test that there is no export list advertised
+nbdinfo --list --json nbd+unix://?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep '"exports": \[]' ext2-exportname.out
+
+:
--
2.28.0
9:32 a.m.
New subject: [nbdkit PATCH 2/2] ext2: Supply .list_exports and .default_export
On Thu, Aug 27, 2020 at 05:03:46PM -0500, Eric Blake wrote:
When using ext2file=exportname to pick the file to server from the
client's export name, we do not want to leak the underlying plugin's
export list. While touching this, take advantage of string lifetimes
via nbdkit_strdup_intern and similar for less cleanup bookkeeping.
Note that we don't actually implement a full .list_exports; doing that
with NBD_OPT_LIST is likely prohibitive (it's likely the disk contains
LOTS of files), and would require that we can do next_ops->pread prior
to the client reaching our .open. For the former issue, it would be
better if the NBD protocol adds a new option NBD_OPT_LIST_HIER that
has replies that differentiate between containers and leaves, and only
lists elements within a container supplied as an argument. For the
latter, we already know we want to tweak filters to be able to open a
plugin independently of a client's connection. And for now we punt,
and leave the advertised list empty.
It's also high time we had some testsuite coverage of
ext2file=exportname. Although ext2.img doesn't technically depend on
the new test, including the dependency ensures the file gets rebuilt
in an incremental build.
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
filters/ext2/nbdkit-ext2-filter.pod | 3 +-
tests/Makefile.am | 16 +++++--
filters/ext2/ext2.c | 73 ++++++++++++++++++++---------
tests/test-ext2-exportname.sh | 73 +++++++++++++++++++++++++++++
4 files changed, 138 insertions(+), 27 deletions(-)
create mode 100755 tests/test-ext2-exportname.sh
diff --git a/filters/ext2/nbdkit-ext2-filter.pod b/filters/ext2/nbdkit-ext2-filter.pod
index 1aef9c2e..c15a2fcb 100644
--- a/filters/ext2/nbdkit-ext2-filter.pod
+++ b/filters/ext2/nbdkit-ext2-filter.pod
@@ -67,7 +67,8 @@ a security risk in some situations.
At present, when using this mode, the server does not advertise any
particular exports; however, you may use
-L<nbdkit-exportname-filter(1)> to perform that task.
+L<nbdkit-exportname-filter(1)> to perform that task. Similarly, the
+underlying plugin must support the default export name, C<"">.
=back
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8a799ccf..911fa2b3 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1373,23 +1373,31 @@ EXTRA_DIST += test-exportname.sh
# ext2 filter test.
if HAVE_MKE2FS_WITH_D
if HAVE_EXT2
-if HAVE_GUESTFISH
-LIBGUESTFS_TESTS += test-ext2
+TESTS += test-ext2-exportname.sh
+EXTRA_DIST += test-ext2-exportname.sh
+
check_DATA += ext2.img
CLEANFILES += ext2.img
-ext2.img: disk
+ext2.img: disk test-ext2-exportname.sh
rm -f $@ $@-t
+ echo /disks/disk.img > manifest
guestfish \
sparse $@-t 2G : \
run : \
mkfs ext4 /dev/sda : \
mount /dev/sda / : \
mkdir /disks : \
- upload $< /disks/disk.img
+ upload $< /disks/disk.img : \
+ upload manifest /manifest
+ rm manifest
mv $@-t $@
+if HAVE_GUESTFISH
+
+LIBGUESTFS_TESTS += test-ext2
+
test_ext2_SOURCES = test-ext2.c test.h
test_ext2_CFLAGS = $(WARNINGS_CFLAGS) $(LIBGUESTFS_CFLAGS)
test_ext2_LDADD = libtest.la $(LIBGUESTFS_LIBS)
diff --git a/filters/ext2/ext2.c b/filters/ext2/ext2.c
index 7ad4a005..cfc03a3c 100644
--- a/filters/ext2/ext2.c
+++ b/filters/ext2/ext2.c
@@ -50,8 +50,10 @@
#include "cleanup.h"
#include "io.h"
-/* Filename parameter, or NULL to honor export name. */
-static char *file;
+/* Filename parameter, or NULL to honor export name. Using the export
+ * name is opt-in (see ext2_config_complete).
+ */
+static const char *file;
static void
ext2_load (void)
@@ -59,12 +61,6 @@ ext2_load (void)
initialize_ext2_error_table ();
}
-static void
-ext2_unload (void)
-{
- free (file);
-}
-
static int
ext2_config (nbdkit_next_config *next, void *nxdata,
const char *key, const char *value)
@@ -74,11 +70,7 @@ ext2_config (nbdkit_next_config *next, void *nxdata,
nbdkit_error ("ext2file parameter specified more than once");
return -1;
}
- file = strdup (value);
- if (file == NULL) {
- nbdkit_error ("strdup: %m");
- return -1;
- }
+ file = value;
return 0;
}
else
@@ -94,10 +86,8 @@ ext2_config_complete (nbdkit_next_config_complete *next, void
*nxdata)
return -1;
}
- if (strcmp (file, "exportname") == 0) {
- free (file);
+ if (strcmp (file, "exportname") == 0)
file = NULL;
- }
else if (file[0] != '/') {
nbdkit_error ("the file parameter must refer to an absolute path");
return -1;
@@ -112,13 +102,54 @@ ext2_config_complete (nbdkit_next_config_complete *next, void
*nxdata)
/* The per-connection handle. */
struct handle {
- char *exportname; /* Client export name. */
+ const char *exportname; /* Client export name. */
ext2_filsys fs; /* Filesystem handle. */
ext2_ino_t ino; /* Inode of open file. */
ext2_file_t file; /* File handle. */
struct nbdkit_next next; /* "name" parameter to ext2fs_open. */
};
+/* Export list. */
+static int
+ext2_list_exports (nbdkit_next_list_exports *next, void *nxdata,
+ int readonly, int is_tls, struct nbdkit_exports *exports)
+{
+ /* If we are honoring export names, the default export "" won't
+ * work, and we must not leak export names from the underlying
+ * plugin. Advertising all filenames within the ext2 image could be
+ * huge, and even if we wanted to, it would require that we could
+ * open the plugin prior to the client reaching our .open. So leave
+ * the list empty instead.
+ */
+ if (!file)
+ return 0;
+
+ /* If we are serving a specific ext2file, we don't care what export
+ * name the user passes, but the underlying plugin might; there's no
+ * harm in advertising that list.
+ */
+ return next (nxdata, readonly, exports);
+}
+
+/* Default export. */
+static const char *
+ext2_default_export (nbdkit_next_default_export *next, void *nxdata,
+ int readonly, int is_tls)
+{
+ /* If we are honoring exports, "" will fail (even if we resolve to
+ * the inode of embedded "/", we can't serve directories), and we
+ * don't really have a sane default. XXX picking the largest
+ * embedded file might be in interesting knob to add.
+ */
+ if (file)
+ return NULL;
+
+ /* Otherwise, we don't care about export name, so keeping things at
+ * "" is fine, regardless of the underlying plugin's default.
+ */
+ return "";
+}
+
/* Create the per-connection handle. */
static void *
ext2_open (nbdkit_next_open *next, void *nxdata,
@@ -133,9 +164,8 @@ ext2_open (nbdkit_next_open *next, void *nxdata,
}
/* Save the client exportname in the handle. */
- h->exportname = strdup (exportname);
+ h->exportname = nbdkit_strdup_intern (exportname);
if (h->exportname == NULL) {
- nbdkit_error ("strdup: %m");
free (h);
return NULL;
}
@@ -147,7 +177,6 @@ ext2_open (nbdkit_next_open *next, void *nxdata,
/* Request write access to the underlying plugin, for journal replay. */
if (next (nxdata, 0, exportname) == -1) {
- free (h->exportname);
free (h);
return NULL;
}
@@ -260,7 +289,6 @@ ext2_close (void *handle)
ext2fs_file_close (h->file);
ext2fs_close (h->fs);
}
- free (h->exportname);
free (h);
}
@@ -434,11 +462,12 @@ static struct nbdkit_filter filter = {
.name = "ext2",
.longname = "nbdkit ext2 filter",
.load = ext2_load,
- .unload = ext2_unload,
.config = ext2_config,
.config_complete = ext2_config_complete,
.config_help = ext2_config_help,
.thread_model = ext2_thread_model,
+ .list_exports = ext2_list_exports,
+ .default_export = ext2_default_export,
.open = ext2_open,
.prepare = ext2_prepare,
.close = ext2_close,
diff --git a/tests/test-ext2-exportname.sh b/tests/test-ext2-exportname.sh
new file mode 100755
index 00000000..b30aa870
--- /dev/null
+++ b/tests/test-ext2-exportname.sh
@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+# nbdkit
+# Copyright (C) 2019-2020 Red Hat Inc.
+#
+# 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.
+
+source ./functions.sh
+set -e
+set -x
+
+requires_plugin file
+requires nbdinfo --version
+requires nbdsh -c 'print (h.set_full_info)'
+
+sock=`mktemp -u`
+files="$sock ext2-exportname.pid ext2-exportname.out"
+rm -f $files
+cleanup_fn rm -f $files
+
+# Set up a long-running server responsive to the client's export name
+start_nbdkit -P ext2-exportname.pid -U $sock --filter=ext2 \
+ --filter=exportname file ext2.img ext2file=exportname \
+ exportname-list=explicit exportname=hidden
+
+# Test that when serving by exportname, our description varies according
+# to the client's request.
+nbdinfo nbd+unix:///manifest\?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep manifest ext2-exportname.out
+grep 'content.*ASCII' ext2-exportname.out
+
+nbdinfo nbd+unix:///disks/disk.img\?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep disk.img ext2-exportname.out
+grep 'content.*MBR' ext2-exportname.out
+
+if nbdinfo nbd+unix://?socket=$sock > ext2-exportname.out; then
+ echo "unexpected success"
+ exit 1
+fi
+
+# Test that there is no export list advertised
+nbdinfo --list --json nbd+unix://?socket=$sock > ext2-exportname.out
+cat ext2-exportname.out
+grep '"exports": \[]' ext2-exportname.out
+
+:
--
ACK
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/
1542
days inactive
1547
days old
5 comments
2 participants
participants (2)
-
Eric Blake -
Richard W.M. Jones