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repo/commit: Dedup metadata writing API implementations

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First, the streaming metadata API is pretty dumb, since metadata
should be small.  Really we should have supported a `GBytes`
version.  Currently, this API *is* used when we do local pulls,
so this commit has test coverage.  However, I plan to change
the object import to avoid using this.  But that's fine, since
I can't think of why someone would use this API.

Next, the only difference between `ostree_repo_write_metadata()` and
`ostree_repo_write_metadata_trusted()` is whether or not we pass
an output checksum; so just dedup the implementations.

Also while I'm here break out the input length validation and do
it early in the streaming case.

Closes: #881
Approved by: jlebon
This commit is contained in:
Colin Walters 2017-05-23 14:49:17 -04:00 committed by Atomic Bot
parent 1eff3e8343
commit 22b1234f52
1 changed files with 41 additions and 24 deletions
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65
src/libostree/ostree-repo-commit.c
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@ -1481,6 +1481,25 @@ ostree_repo_abort_transaction (OstreeRepo *self,
return TRUE;
}
/* These limits were introduced since in some cases we may be processing
* malicious metadata, and we want to make disk space exhaustion attacks harder.
*/
static gboolean
metadata_size_valid (OstreeObjectType objtype,
gsize len,
GError **error)
{
if (G_UNLIKELY (len > OSTREE_MAX_METADATA_SIZE))
{
g_autofree char *input_bytes = g_format_size (len);
g_autofree char *max_bytes = g_format_size (OSTREE_MAX_METADATA_SIZE);
return glnx_throw (error, "Metadata object of type '%s' is %s; maximum metadata size is %s",
ostree_object_type_to_string (objtype), input_bytes, max_bytes);
}
return TRUE;
}
/**
* ostree_repo_write_metadata:
* @self: Repo
@ -1506,20 +1525,11 @@ ostree_repo_write_metadata (OstreeRepo *self,
GCancellable *cancellable,
GError **error)
{
g_autoptr(GVariant) normalized = NULL;
normalized = g_variant_get_normal_form (object);
if (G_UNLIKELY (g_variant_get_size (normalized) > OSTREE_MAX_METADATA_SIZE))
{
g_autofree char *input_bytes = g_format_size (g_variant_get_size (normalized));
g_autofree char *max_bytes = g_format_size (OSTREE_MAX_METADATA_SIZE);
return glnx_throw (error, "Metadata object of type '%s' is %s; maximum metadata size is %s",
ostree_object_type_to_string (objtype), input_bytes, max_bytes);
}
g_autoptr(GVariant) normalized = g_variant_get_normal_form (object);
if (!metadata_size_valid (objtype, g_variant_get_size (normalized), error))
return FALSE;
g_autoptr(GInputStream) input = ot_variant_read (normalized);
if (!write_object (self, objtype, expected_checksum,
input, g_variant_get_size (normalized),
out_csum,
@ -1551,8 +1561,22 @@ ostree_repo_write_metadata_stream_trusted (OstreeRepo *self,
GCancellable *cancellable,
GError **error)
{
return write_object (self, objtype, checksum, object_input, length, NULL,
cancellable, error);
if (length > 0 && !metadata_size_valid (objtype, length, error))
return FALSE;
/* This is all pretty ridiculous, but we're keeping this API for backwards
* compatibility, it doesn't really need to be fast.
*/
g_autoptr(GMemoryOutputStream) tmpbuf = (GMemoryOutputStream*)g_memory_output_stream_new_resizable ();
if (g_output_stream_splice ((GOutputStream*)tmpbuf, object_input,
G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET, cancellable, error) < 0)
return FALSE;
g_autoptr(GBytes) tmpb = g_memory_output_stream_steal_as_bytes (tmpbuf);
g_autoptr(GVariant) tmpv = g_variant_new_from_bytes (ostree_metadata_variant_type (objtype),
tmpb, TRUE);
return ostree_repo_write_metadata_trusted (self, objtype, checksum, tmpv,
cancellable, error);
}
/**
@ -1575,16 +1599,9 @@ ostree_repo_write_metadata_trusted (OstreeRepo *self,
GCancellable *cancellable,
GError **error)
{
g_autoptr(GInputStream) input = NULL;
g_autoptr(GVariant) normalized = NULL;
normalized = g_variant_get_normal_form (variant);
input = ot_variant_read (normalized);
return write_object (self, type, checksum,
input, g_variant_get_size (normalized),
NULL,
cancellable, error);
return ostree_repo_write_metadata (self, type,
checksum, variant, NULL,
cancellable, error);
}
typedef struct {