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2022-06-23Git 2.30.5v2.30.5Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-06-23setup: tighten ownership checks post CVE-2022-24765Carlo Marcelo Arenas Belón
8959555cee7 (setup_git_directory(): add an owner check for the top-level directory, 2022-03-02), adds a function to check for ownership of repositories using a directory that is representative of it, and ways to add exempt a specific repository from said check if needed, but that check didn't account for owership of the gitdir, or (when used) the gitfile that points to that gitdir. An attacker could create a git repository in a directory that they can write into but that is owned by the victim to work around the fix that was introduced with CVE-2022-24765 to potentially run code as the victim. An example that could result in privilege escalation to root in *NIX would be to set a repository in a shared tmp directory by doing (for example): $ git -C /tmp init To avoid that, extend the ensure_valid_ownership function to be able to check for all three paths. This will have the side effect of tripling the number of stat() calls when a repository is detected, but the effect is expected to be likely minimal, as it is done only once during the directory walk in which Git looks for a repository. Additionally make sure to resolve the gitfile (if one was used) to find the relevant gitdir for checking. While at it change the message printed on failure so it is clear we are referring to the repository by its worktree (or gitdir if it is bare) and not to a specific directory. Helped-by: Junio C Hamano <junio@pobox.com> Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
2022-06-23Merge branch 'cb/path-owner-check-with-sudo'Junio C Hamano
With a recent update to refuse access to repositories of other people by default, "sudo make install" and "sudo git describe" stopped working. This series intends to loosen it while keeping the safety. * cb/path-owner-check-with-sudo: t0034: add negative tests and allow git init to mostly work under sudo git-compat-util: avoid failing dir ownership checks if running privileged t: regression git needs safe.directory when using sudo Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-06-17git-compat-util: allow root to access both SUDO_UID and root ownedCarlo Marcelo Arenas Belón
Previous changes introduced a regression which will prevent root for accessing repositories owned by thyself if using sudo because SUDO_UID takes precedence. Loosen that restriction by allowing root to access repositories owned by both uid by default and without having to add a safe.directory exception. A previous workaround that was documented in the tests is no longer needed so it has been removed together with its specially crafted prerequisite. Helped-by: Johanness Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-05-12t0034: add negative tests and allow git init to mostly work under sudoCarlo Marcelo Arenas Belón
Add a support library that provides one function that can be used to run a "scriplet" of commands through sudo and that helps invoking sudo in the slightly awkward way that is required to ensure it doesn't block the call (if shell was allowed as tested in the prerequisite) and it doesn't run the command through a different shell than the one we intended. Add additional negative tests as suggested by Junio and that use a new workspace that is owned by root. Document a regression that was introduced by previous commits where root won't be able anymore to access directories they own unless SUDO_UID is removed from their environment. The tests document additional ways that this new restriction could be worked around and the documentation explains why it might be instead considered a feature, but a "fix" is planned for a future change. Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Phillip Wood <phillip.wood123@gmail.com> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-05-12git-compat-util: avoid failing dir ownership checks if running privilegedCarlo Marcelo Arenas Belón
bdc77d1d685 (Add a function to determine whether a path is owned by the current user, 2022-03-02) checks for the effective uid of the running process using geteuid() but didn't account for cases where that user was root (because git was invoked through sudo or a compatible tool) and the original uid that repository trusted for its config was no longer known, therefore failing the following otherwise safe call: guy@renard ~/Software/uncrustify $ sudo git describe --always --dirty [sudo] password for guy: fatal: unsafe repository ('/home/guy/Software/uncrustify' is owned by someone else) Attempt to detect those cases by using the environment variables that those tools create to keep track of the original user id, and do the ownership check using that instead. This assumes the environment the user is running on after going privileged can't be tampered with, and also adds code to restrict that the new behavior only applies if running as root, therefore keeping the most common case, which runs unprivileged, from changing, but because of that, it will miss cases where sudo (or an equivalent) was used to change to another unprivileged user or where the equivalent tool used to raise privileges didn't track the original id in a sudo compatible way. Because of compatibility with sudo, the code assumes that uid_t is an unsigned integer type (which is not required by the standard) but is used that way in their codebase to generate SUDO_UID. In systems where uid_t is signed, sudo might be also patched to NOT be unsigned and that might be able to trigger an edge case and a bug (as described in the code), but it is considered unlikely to happen and even if it does, the code would just mostly fail safely, so there was no attempt either to detect it or prevent it by the code, which is something that might change in the future, based on expected user feedback. Reported-by: Guy Maurel <guy.j@maurel.de> Helped-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Randall Becker <rsbecker@nexbridge.com> Helped-by: Phillip Wood <phillip.wood123@gmail.com> Suggested-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-05-12t: regression git needs safe.directory when using sudoCarlo Marcelo Arenas Belón
Originally reported after release of v2.35.2 (and other maint branches) for CVE-2022-24765 and blocking otherwise harmless commands that were done using sudo in a repository that was owned by the user. Add a new test script with very basic support to allow running git commands through sudo, so a reproduction could be implemented and that uses only `git status` as a proxy of the issue reported. Note that because of the way sudo interacts with the system, a much more complete integration with the test framework will require a lot more work and that was therefore intentionally punted for now. The current implementation requires the execution of a special cleanup function which should always be kept as the last "test" or otherwise the standard cleanup functions will fail because they can't remove the root owned directories that are used. This also means that if failures are found while running, the specifics of the failure might not be kept for further debugging and if the test was interrupted, it will be necessary to clean the working directory manually before restarting by running: $ sudo rm -rf trash\ directory.t0034-root-safe-directory/ The test file also uses at least one initial "setup" test that creates a parallel execution directory under the "root" sub directory, which should be used as top level directory for all repositories that are used in this test file. Unlike all other tests the repository provided by the test framework should go unused. Special care should be taken when invoking commands through sudo, since the environment is otherwise independent from what the test framework setup and might have changed the values for HOME, SHELL and dropped several relevant environment variables for your test. Indeed `git status` was used as a proxy because it doesn't even require commits in the repository to work and usually doesn't require much from the environment to run, but a future patch will add calls to `git init` and that will fail to honor the default branch name, unless that setting is NOT provided through an environment variable (which means even a CI run could fail that test if enabled incorrectly). A new SUDO prerequisite is provided that does some sanity checking to make sure the sudo command that will be used allows for passwordless execution as root without restrictions and doesn't mess with git's execution path. This matches what is provided by the macOS agents that are used as part of GitHub actions and probably nowhere else. Most of those characteristics make this test mostly only suitable for CI, but it might be executed locally if special care is taken to provide for all of them in the local configuration and maybe making use of the sudo credential cache by first invoking sudo, entering your password if needed, and then invoking the test with: $ GIT_TEST_ALLOW_SUDO=YES ./t0034-root-safe-directory.sh If it fails to run, then it means your local setup wouldn't work for the test because of the configuration sudo has or other system settings, and things that might help are to comment out sudo's secure_path config, and make sure that the account you are using has no restrictions on the commands it can run through sudo, just like is provided for the user in the CI. For example (assuming a username of marta for you) something probably similar to the following entry in your /etc/sudoers (or equivalent) file: marta ALL=(ALL:ALL) NOPASSWD: ALL Reported-by: SZEDER Gábor <szeder.dev@gmail.com> Helped-by: Phillip Wood <phillip.wood123@gmail.com> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-04-13Git 2.30.4v2.30.4Junio C Hamano
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-04-13setup: opt-out of check with safe.directory=*Derrick Stolee
With the addition of the safe.directory in 8959555ce (setup_git_directory(): add an owner check for the top-level directory, 2022-03-02) released in v2.35.2, we are receiving feedback from a variety of users about the feature. Some users have a very large list of shared repositories and find it cumbersome to add this config for every one of them. In a more difficult case, certain workflows involve running Git commands within containers. The container boundary prevents any global or system config from communicating `safe.directory` values from the host into the container. Further, the container almost always runs as a different user than the owner of the directory in the host. To simplify the reactions necessary for these users, extend the definition of the safe.directory config value to include a possible '*' value. This value implies that all directories are safe, providing a single setting to opt-out of this protection. Note that an empty assignment of safe.directory clears all previous values, and this is already the case with the "if (!value || !*value)" condition. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-04-13setup: fix safe.directory key not being checkedMatheus Valadares
It seems that nothing is ever checking to make sure the safe directories in the configs actually have the key safe.directory, so some unrelated config that has a value with a certain directory would also make it a safe directory. Signed-off-by: Matheus Valadares <me@m28.io> Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-04-13t0033: add tests for safe.directoryDerrick Stolee
It is difficult to change the ownership on a directory in our test suite, so insert a new GIT_TEST_ASSUME_DIFFERENT_OWNER environment variable to trick Git into thinking we are in a differently-owned directory. This allows us to test that the config is parsed correctly. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-24Git 2.30.3v2.30.3Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-24Fix `GIT_CEILING_DIRECTORIES` with `C:\` and the likesJohannes Schindelin
When determining the length of the longest ancestor of a given path with respect to to e.g. `GIT_CEILING_DIRECTORIES`, we special-case the root directory by returning 0 (i.e. we pretend that the path `/` does not end in a slash by virtually stripping it). That is the correct behavior because when normalizing paths, the root directory is special: all other directory paths have their trailing slash stripped, but not the root directory's path (because it would become the empty string, which is not a legal path). However, this special-casing of the root directory in `longest_ancestor_length()` completely forgets about Windows-style root directories, e.g. `C:\`. These _also_ get normalized with a trailing slash (because `C:` would actually refer to the current directory on that drive, not necessarily to its root directory). In fc56c7b34b (mingw: accomodate t0060-path-utils for MSYS2, 2016-01-27), we almost got it right. We noticed that `longest_ancestor_length()` expects a slash _after_ the matched prefix, and if the prefix already ends in a slash, the normalized path won't ever match and -1 is returned. But then that commit went astray: The correct fix is not to adjust the _tests_ to expect an incorrect -1 when that function is fed a prefix that ends in a slash, but instead to treat such a prefix as if the trailing slash had been removed. Likewise, that function needs to handle the case where it is fed a path that ends in a slash (not only a prefix that ends in a slash): if it matches the prefix (plus trailing slash), we still need to verify that the path does not end there, otherwise the prefix is not actually an ancestor of the path but identical to it (and we need to return -1 in that case). With these two adjustments, we no longer need to play games in t0060 where we only add `$rootoff` if the passed prefix is different from the MSYS2 pseudo root, instead we also add it for the MSYS2 pseudo root itself. We do have to be careful to skip that logic entirely for Windows paths, though, because they do are not subject to that MSYS2 pseudo root treatment. This patch fixes the scenario where a user has set `GIT_CEILING_DIRECTORIES=C:\`, which would be ignored otherwise. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-21setup_git_directory(): add an owner check for the top-level directoryJohannes Schindelin
It poses a security risk to search for a git directory outside of the directories owned by the current user. For example, it is common e.g. in computer pools of educational institutes to have a "scratch" space: a mounted disk with plenty of space that is regularly swiped where any authenticated user can create a directory to do their work. Merely navigating to such a space with a Git-enabled `PS1` when there is a maliciously-crafted `/scratch/.git/` can lead to a compromised account. The same holds true in multi-user setups running Windows, as `C:\` is writable to every authenticated user by default. To plug this vulnerability, we stop Git from accepting top-level directories owned by someone other than the current user. We avoid looking at the ownership of each and every directories between the current and the top-level one (if there are any between) to avoid introducing a performance bottleneck. This new default behavior is obviously incompatible with the concept of shared repositories, where we expect the top-level directory to be owned by only one of its legitimate users. To re-enable that use case, we add support for adding exceptions from the new default behavior via the config setting `safe.directory`. The `safe.directory` config setting is only respected in the system and global configs, not from repository configs or via the command-line, and can have multiple values to allow for multiple shared repositories. We are particularly careful to provide a helpful message to any user trying to use a shared repository. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-21Add a function to determine whether a path is owned by the current userJohannes Schindelin
This function will be used in the next commit to prevent `setup_git_directory()` from discovering a repository in a directory that is owned by someone other than the current user. Note: We cannot simply use `st.st_uid` on Windows just like we do on Linux and other Unix-like platforms: according to https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/stat-functions this field is always zero on Windows (because Windows' idea of a user ID does not fit into a single numerical value). Therefore, we have to do something a little involved to replicate the same functionality there. Also note: On Windows, a user's home directory is not actually owned by said user, but by the administrator. For all practical purposes, it is under the user's control, though, therefore we pretend that it is owned by the user. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-17Merge branch 'cb/mingw-gmtime-r'Johannes Schindelin
Build fix on Windows. * cb/mingw-gmtime-r: mingw: avoid fallback for {local,gm}time_r() Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-17mingw: avoid fallback for {local,gm}time_r()Carlo Marcelo Arenas Belón
mingw-w64's pthread_unistd.h had a bug that mistakenly (because there is no support for the *lockfile() functions required[1]) defined _POSIX_THREAD_SAFE_FUNCTIONS and that was being worked around since 3ecd153a3b (compat/mingw: support MSys2-based MinGW build, 2016-01-14). The bug was fixed in winphtreads, but as a side effect, leaves the reentrant functions from time.h no longer visible and therefore breaks the build. Since the intention all along was to avoid using the fallback functions, formalize the use of POSIX by setting the corresponding feature flag and compile out the implementation for the fallback functions. [1] https://unix.org/whitepapers/reentrant.html Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-12Git 2.30.2v2.30.2Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.29.3Johannes Schindelin
* maint-2.29: Git 2.29.3 Git 2.28.1 Git 2.27.1 Git 2.26.3 Git 2.25.5 Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.29.3v2.29.3Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.28.1Johannes Schindelin
* maint-2.28: Git 2.28.1 Git 2.27.1 Git 2.26.3 Git 2.25.5 Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.28.1v2.28.1Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.27.1Johannes Schindelin
* maint-2.27: Git 2.27.1 Git 2.26.3 Git 2.25.5 Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.27.1v2.27.1Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.26.3Johannes Schindelin
* maint-2.26: Git 2.26.3 Git 2.25.5 Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.26.3v2.26.3Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.25.5Johannes Schindelin
* maint-2.25: Git 2.25.5 Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.25.5v2.25.5Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.24.4Johannes Schindelin
* maint-2.24: Git 2.24.4 Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.24.4v2.24.4Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.23.4Johannes Schindelin
* maint-2.23: Git 2.23.4 Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.23.4v2.23.4Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.22.5Johannes Schindelin
* maint-2.22: Git 2.22.5 Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.22.5v2.22.5Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.21.4Johannes Schindelin
* maint-2.21: Git 2.21.4 Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.21.4v2.21.4Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.20.5Johannes Schindelin
* maint-2.20: Git 2.20.5 Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.20.5v2.20.5Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.19.6Johannes Schindelin
* maint-2.19: Git 2.19.6 Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.19.6v2.19.6Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.18.5Johannes Schindelin
* maint-2.18: Git 2.18.5 Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.18.5v2.18.5Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12Sync with 2.17.6Johannes Schindelin
* maint-2.17: Git 2.17.6 unpack_trees(): start with a fresh lstat cache run-command: invalidate lstat cache after a command finished checkout: fix bug that makes checkout follow symlinks in leading path
2021-02-12Git 2.17.6v2.17.6Johannes Schindelin
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12unpack_trees(): start with a fresh lstat cacheMatheus Tavares
We really want to avoid relying on stale information. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12run-command: invalidate lstat cache after a command finishedJohannes Schindelin
In the previous commit, we intercepted calls to `rmdir()` to invalidate the lstat cache in the successful case, so that the lstat cache could not have the idea that a directory exists where there is none. The same situation can arise, of course, when a separate process is spawned (most notably, this is the case in `submodule_move_head()`). Obviously, we cannot know whether a directory was removed in that process, therefore we must invalidate the lstat cache afterwards. Note: in contrast to `lstat_cache_aware_rmdir()`, we invalidate the lstat cache even in case of an error: the process might have removed a directory and still have failed afterwards. Co-authored-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2021-02-12checkout: fix bug that makes checkout follow symlinks in leading pathMatheus Tavares
Before checking out a file, we have to confirm that all of its leading components are real existing directories. And to reduce the number of lstat() calls in this process, we cache the last leading path known to contain only directories. However, when a path collision occurs (e.g. when checking out case-sensitive files in case-insensitive file systems), a cached path might have its file type changed on disk, leaving the cache on an invalid state. Normally, this doesn't bring any bad consequences as we usually check out files in index order, and therefore, by the time the cached path becomes outdated, we no longer need it anyway (because all files in that directory would have already been written). But, there are some users of the checkout machinery that do not always follow the index order. In particular: checkout-index writes the paths in the same order that they appear on the CLI (or stdin); and the delayed checkout feature -- used when a long-running filter process replies with "status=delayed" -- postpones the checkout of some entries, thus modifying the checkout order. When we have to check out an out-of-order entry and the lstat() cache is invalid (due to a previous path collision), checkout_entry() may end up using the invalid data and thrusting that the leading components are real directories when, in reality, they are not. In the best case scenario, where the directory was replaced by a regular file, the user will get an error: "fatal: unable to create file 'foo/bar': Not a directory". But if the directory was replaced by a symlink, checkout could actually end up following the symlink and writing the file at a wrong place, even outside the repository. Since delayed checkout is affected by this bug, it could be used by an attacker to write arbitrary files during the clone of a maliciously crafted repository. Some candidate solutions considered were to disable the lstat() cache during unordered checkouts or sort the entries before passing them to the checkout machinery. But both ideas include some performance penalty and they don't future-proof the code against new unordered use cases. Instead, we now manually reset the lstat cache whenever we successfully remove a directory. Note: We are not even checking whether the directory was the same as the lstat cache points to because we might face a scenario where the paths refer to the same location but differ due to case folding, precomposed UTF-8 issues, or the presence of `..` components in the path. Two regression tests, with case-collisions and utf8-collisions, are also added for both checkout-index and delayed checkout. Note: to make the previously mentioned clone attack unfeasible, it would be sufficient to reset the lstat cache only after the remove_subtree() call inside checkout_entry(). This is the place where we would remove a directory whose path collides with the path of another entry that we are currently trying to check out (possibly a symlink). However, in the interest of a thorough fix that does not leave Git open to similar-but-not-identical attack vectors, we decided to intercept all `rmdir()` calls in one fell swoop. This addresses CVE-2021-21300. Co-authored-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
2021-02-11Merge branch 'tb/ci-run-cocci-with-18.04' into maintJunio C Hamano
* tb/ci-run-cocci-with-18.04: .github/workflows/main.yml: run static-analysis on bionic
2021-02-08.github/workflows/main.yml: run static-analysis on bionicTaylor Blau
GitHub Actions is transitioning workflow steps that run on 'ubuntu-latest' from 18.04 to 20.04 [1]. This works fine in all steps except the static-analysis one, since Coccinelle isn't available on Ubuntu focal (it is only available in the universe suite). Until Coccinelle can be installed from 20.04's main suite, pin the static-analysis build to run on 18.04, where it can be installed by default. [1]: https://github.com/actions/virtual-environments/issues/1816 Reported-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-08Git 2.30.1v2.30.1Junio C Hamano
Signed-off-by: Junio C Hamano <gitster@pobox.com>