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
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
ls-remote.c
#include "builtin.h"
#include "cache.h"
#include "transport.h"
#include "ref-filter.h"
#include "remote.h"
#include "refs.h"

static const char * const ls_remote_usage[] = {
	N_("git ls-remote [--heads] [--tags] [--refs] [--upload-pack=<exec>]\n"
	   "              [-q | --quiet] [--exit-code] [--get-url] [--sort=<key>]\n"
	   "              [--symref] [<repository> [<refs>...]]"),
	NULL
};

/*
 * Is there one among the list of patterns that match the tail part
 * of the path?
 */
static int tail_match(const char **pattern, const char *path)
{
	const char *p;
	char *pathbuf;

	if (!pattern)
		return 1; /* no restriction */

	pathbuf = xstrfmt("/%s", path);
	while ((p = *(pattern++)) != NULL) {
		if (!wildmatch(p, pathbuf, 0)) {
			free(pathbuf);
			return 1;
		}
	}
	free(pathbuf);
	return 0;
}

int cmd_ls_remote(int argc, const char **argv, const char *prefix)
{
	const char *dest = NULL;
	unsigned flags = 0;
	int get_url = 0;
	int quiet = 0;
	int status = 0;
	int show_symref_target = 0;
	const char *uploadpack = NULL;
	const char **pattern = NULL;
	struct transport_ls_refs_options transport_options =
		TRANSPORT_LS_REFS_OPTIONS_INIT;
	int i;
	struct string_list server_options = STRING_LIST_INIT_DUP;

	struct remote *remote;
	struct transport *transport;
	const struct ref *ref;
	struct ref_array ref_array;
	struct string_list sorting_options = STRING_LIST_INIT_DUP;

	struct option options[] = {
		OPT__QUIET(&quiet, N_("do not print remote URL")),
		OPT_STRING(0, "upload-pack", &uploadpack, N_("exec"),
			   N_("path of git-upload-pack on the remote host")),
		{ OPTION_STRING, 0, "exec", &uploadpack, N_("exec"),
			   N_("path of git-upload-pack on the remote host"),
			   PARSE_OPT_HIDDEN },
		OPT_BIT('t', "tags", &flags, N_("limit to tags"), REF_TAGS),
		OPT_BIT('h', "heads", &flags, N_("limit to heads"), REF_HEADS),
		OPT_BIT(0, "refs", &flags, N_("do not show peeled tags"), REF_NORMAL),
		OPT_BOOL(0, "get-url", &get_url,
			 N_("take url.<base>.insteadOf into account")),
		OPT_REF_SORT(&sorting_options),
		OPT_SET_INT_F(0, "exit-code", &status,
			      N_("exit with exit code 2 if no matching refs are found"),
			      2, PARSE_OPT_NOCOMPLETE),
		OPT_BOOL(0, "symref", &show_symref_target,
			 N_("show underlying ref in addition to the object pointed by it")),
		OPT_STRING_LIST('o', "server-option", &server_options, N_("server-specific"), N_("option to transmit")),
		OPT_END()
	};

	memset(&ref_array, 0, sizeof(ref_array));

	argc = parse_options(argc, argv, prefix, options, ls_remote_usage,
			     PARSE_OPT_STOP_AT_NON_OPTION);
	dest = argv[0];

	packet_trace_identity("ls-remote");

	if (argc > 1) {
		int i;
		CALLOC_ARRAY(pattern, argc);
		for (i = 1; i < argc; i++) {
			pattern[i - 1] = xstrfmt("*/%s", argv[i]);
		}
	}

	if (flags & REF_TAGS)
		strvec_push(&transport_options.ref_prefixes, "refs/tags/");
	if (flags & REF_HEADS)
		strvec_push(&transport_options.ref_prefixes, "refs/heads/");

	remote = remote_get(dest);
	if (!remote) {
		if (dest)
			die("bad repository '%s'", dest);
		die("No remote configured to list refs from.");
	}
	if (!remote->url_nr)
		die("remote %s has no configured URL", dest);

	if (get_url) {
		printf("%s\n", *remote->url);
		return 0;
	}

	transport = transport_get(remote, NULL);
	if (uploadpack)
		transport_set_option(transport, TRANS_OPT_UPLOADPACK, uploadpack);
	if (server_options.nr)
		transport->server_options = &server_options;

	ref = transport_get_remote_refs(transport, &transport_options);
	if (ref) {
		int hash_algo = hash_algo_by_ptr(transport_get_hash_algo(transport));
		repo_set_hash_algo(the_repository, hash_algo);
	}

	if (!dest && !quiet)
		fprintf(stderr, "From %s\n", *remote->url);
	for ( ; ref; ref = ref->next) {
		struct ref_array_item *item;
		if (!check_ref_type(ref, flags))
			continue;
		if (!tail_match(pattern, ref->name))
			continue;
		item = ref_array_push(&ref_array, ref->name, &ref->old_oid);
		item->symref = xstrdup_or_null(ref->symref);
	}

	if (sorting_options.nr) {
		struct ref_sorting *sorting;

		sorting = ref_sorting_options(&sorting_options);
		ref_array_sort(sorting, &ref_array);
		ref_sorting_release(sorting);
	}

	for (i = 0; i < ref_array.nr; i++) {
		const struct ref_array_item *ref = ref_array.items[i];
		if (show_symref_target && ref->symref)
			printf("ref: %s\t%s\n", ref->symref, ref->refname);
		printf("%s\t%s\n", oid_to_hex(&ref->objectname), ref->refname);
		status = 0; /* we found something */
	}

	ref_array_clear(&ref_array);
	if (transport_disconnect(transport))
		status = 1;
	transport_ls_refs_options_release(&transport_options);
	return status;
}
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