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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
column.c 
#include "builtin.h"
#include "cache.h"
#include "config.h"
#include "strbuf.h"
#include "parse-options.h"
#include "string-list.h"
#include "column.h"

static const char * const builtin_column_usage[] = {
	N_("git column [<options>]"),
	NULL
};
static unsigned int colopts;

static int column_config(const char *var, const char *value, void *cb)
{
	return git_column_config(var, value, cb, &colopts);
}

int cmd_column(int argc, const char **argv, const char *prefix)
{
	struct string_list list = STRING_LIST_INIT_DUP;
	struct strbuf sb = STRBUF_INIT;
	struct column_options copts;
	const char *command = NULL, *real_command = NULL;
	struct option options[] = {
		OPT_STRING(0, "command", &real_command, N_("name"), N_("lookup config vars")),
		OPT_COLUMN(0, "mode", &colopts, N_("layout to use")),
		OPT_INTEGER(0, "raw-mode", &colopts, N_("layout to use")),
		OPT_INTEGER(0, "width", &copts.width, N_("maximum width")),
		OPT_STRING(0, "indent", &copts.indent, N_("string"), N_("padding space on left border")),
		OPT_STRING(0, "nl", &copts.nl, N_("string"), N_("padding space on right border")),
		OPT_INTEGER(0, "padding", &copts.padding, N_("padding space between columns")),
		OPT_END()
	};

	/* This one is special and must be the first one */
	if (argc > 1 && starts_with(argv[1], "--command=")) {
		command = argv[1] + 10;
		git_config(column_config, (void *)command);
	} else
		git_config(column_config, NULL);

	memset(&copts, 0, sizeof(copts));
	copts.padding = 1;
	argc = parse_options(argc, argv, prefix, options, builtin_column_usage, 0);
	if (argc)
		usage_with_options(builtin_column_usage, options);
	if (real_command || command) {
		if (!real_command || !command || strcmp(real_command, command))
			die(_("--command must be the first argument"));
	}
	finalize_colopts(&colopts, -1);
	while (!strbuf_getline(&sb, stdin))
		string_list_append(&list, sb.buf);

	print_columns(&list, colopts, &copts);
	return 0;
}
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