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Revision 9cf85473209ea8ae2b56c13145c4704d12ee1374 authored by Filip Hejsek on 28 January 2024, 04:09:17 UTC, committed by Johannes Schindelin on 17 April 2024, 20:30:01 UTC 
clone: prevent clashing git dirs when cloning submodule in parallel
 
While it is expected to have several git dirs within the `.git/modules/`
tree, it is important that they do not interfere with each other. For
example, if one submodule was called "captain" and another submodule
"captain/hooks", their respective git dirs would clash, as they would be
located in `.git/modules/captain/` and `.git/modules/captain/hooks/`,
respectively, i.e. the latter's files could clash with the actual Git
hooks of the former.

To prevent these clashes, and in particular to prevent hooks from being
written and then executed as part of a recursive clone, we introduced
checks as part of the fix for CVE-2019-1387 in a8dee3ca61 (Disallow
dubiously-nested submodule git directories, 2019-10-01).

It is currently possible to bypass the check for clashing submodule
git dirs in two ways:

1. parallel cloning
2. checkout --recurse-submodules

Let's check not only before, but also after parallel cloning (and before
checking out the submodule), that the git dir is not clashing with
another one, otherwise fail. This addresses the parallel cloning issue.

As to the parallel checkout issue: It requires quite a few manual steps
to create clashing git dirs because Git itself would refuse to
initialize the inner one, as demonstrated by the test case.

Nevertheless, let's teach the recursive checkout (namely, the
`submodule_move_head()` function that is used by the recursive checkout)
to be careful to verify that it does not use a clashing git dir, and if
it does, disable it (by deleting the `HEAD` file so that subsequent Git
calls won't recognize it as a git dir anymore).

Note: The parallel cloning test case contains a `cat err` that proved to
be highly useful when analyzing the racy nature of the operation (the
operation can fail with three different error messages, depending on
timing), and was left on purpose to ease future debugging should the
need arise.

Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
1 parent b20c10f
Raw File
patch-ids.h 
#ifndef PATCH_IDS_H
#define PATCH_IDS_H

#include "diff.h"
#include "hashmap.h"

struct commit;
struct object_id;
struct repository;

struct patch_id {
	struct hashmap_entry ent;
	struct object_id patch_id;
	struct commit *commit;
};

struct patch_ids {
	struct hashmap patches;
	struct diff_options diffopts;
};

int commit_patch_id(struct commit *commit, struct diff_options *options,
		    struct object_id *oid, int);
int init_patch_ids(struct repository *, struct patch_ids *);
int free_patch_ids(struct patch_ids *);

/* Add a patch_id for a single commit to the set. */
struct patch_id *add_commit_patch_id(struct commit *, struct patch_ids *);

/* Returns true if the patch-id of "commit" is present in the set. */
int has_commit_patch_id(struct commit *commit, struct patch_ids *);

/*
 * Iterate over all commits in the set whose patch id matches that of
 * "commit", like:
 *
 *   struct patch_id *cur;
 *   for (cur = patch_id_iter_first(commit, ids);
 *        cur;
 *        cur = patch_id_iter_next(cur, ids) {
 *           ... look at cur->commit
 *   }
 */
struct patch_id *patch_id_iter_first(struct commit *commit, struct patch_ids *);
struct patch_id *patch_id_iter_next(struct patch_id *cur, struct patch_ids *);

#endif /* PATCH_IDS_H */
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