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>
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fetch-negotiator.h
#ifndef FETCH_NEGOTIATOR_H
#define FETCH_NEGOTIATOR_H
struct commit;
struct repository;
/*
* An object that supplies the information needed to negotiate the contents of
* the to-be-sent packfile during a fetch.
*
* To set up the negotiator, call fetch_negotiator_init(), then known_common()
* (0 or more times), then add_tip() (0 or more times).
*
* Then, when "have" lines are required, call next(). Call ack() to report what
* the server tells us.
*
* Once negotiation is done, call release(). The negotiator then cannot be used
* (unless reinitialized with fetch_negotiator_init()).
*/
struct fetch_negotiator {
/*
* Before negotiation starts, indicate that the server is known to have
* this commit.
*/
void (*known_common)(struct fetch_negotiator *, struct commit *);
/*
* Once this function is invoked, known_common() cannot be invoked any
* more.
*
* Indicate that this commit and all its ancestors are to be checked
* for commonality with the server.
*/
void (*add_tip)(struct fetch_negotiator *, struct commit *);
/*
* Once this function is invoked, known_common() and add_tip() cannot
* be invoked any more.
*
* Return the next commit that the client should send as a "have" line.
*/
const struct object_id *(*next)(struct fetch_negotiator *);
/*
* Inform the negotiator that the server has the given commit. This
* method must only be called on commits returned by next().
*/
int (*ack)(struct fetch_negotiator *, struct commit *);
void (*release)(struct fetch_negotiator *);
/* internal use */
void *data;
};
/*
* Initialize a negotiator based on the repository settings.
*/
void fetch_negotiator_init(struct repository *r,
struct fetch_negotiator *negotiator);
/*
* Initialize a noop negotiator.
*/
void fetch_negotiator_init_noop(struct fetch_negotiator *negotiator);
#endif
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