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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>
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archive.h 
#ifndef ARCHIVE_H
#define ARCHIVE_H

#include "cache.h"
#include "pathspec.h"

struct repository;
struct pretty_print_context;

struct archiver_args {
	struct repository *repo;
	char *refname;
	const char *prefix;
	const char *base;
	size_t baselen;
	struct tree *tree;
	const struct object_id *commit_oid;
	const struct commit *commit;
	timestamp_t time;
	struct pathspec pathspec;
	unsigned int verbose : 1;
	unsigned int worktree_attributes : 1;
	unsigned int convert : 1;
	int compression_level;
	struct string_list extra_files;
	struct pretty_print_context *pretty_ctx;
};

/* main api */

int write_archive(int argc, const char **argv, const char *prefix,
		  struct repository *repo,
		  const char *name_hint, int remote);

const char *archive_format_from_filename(const char *filename);

/* archive backend stuff */

#define ARCHIVER_WANT_COMPRESSION_LEVELS 1
#define ARCHIVER_REMOTE 2
#define ARCHIVER_HIGH_COMPRESSION_LEVELS 4
struct archiver {
	const char *name;
	int (*write_archive)(const struct archiver *, struct archiver_args *);
	unsigned flags;
	char *filter_command;
};
void register_archiver(struct archiver *);

void init_tar_archiver(void);
void init_zip_archiver(void);
void init_archivers(void);

typedef int (*write_archive_entry_fn_t)(struct archiver_args *args,
					const struct object_id *oid,
					const char *path, size_t pathlen,
					unsigned int mode,
					void *buffer, unsigned long size);

int write_archive_entries(struct archiver_args *args, write_archive_entry_fn_t write_entry);

#endif	/* ARCHIVE_H */
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