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submodules: submodule paths must not contain symlinks

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When creating a submodule path, we must be careful not to follow
symbolic links. Otherwise we may follow a symbolic link pointing to
a gitdir (which are valid symbolic links!) e.g. while cloning.

On case-insensitive filesystems, however, we blindly replace a directory
that has been created as part of the `clone` operation with a symlink
when the path to the latter differs only in case from the former's path.

Let's simply avoid this situation by expecting not ever having to
overwrite any existing file/directory/symlink upon cloning. That way, we
won't even replace a directory that we just created.

This addresses CVE-2024-32002.

Reported-by: Filip Hejsek <filip.hejsek@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This commit is contained in:
Johannes Schindelin 2024-03-22 11:19:22 +01:00
parent 9cf8547320
commit 9706576133
2 changed files with 83 additions and 0 deletions
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35
builtin/submodule--helper.c
View File

@ -1641,12 +1641,35 @@ static char *clone_submodule_sm_gitdir(const char *name)
return sm_gitdir;
}
static int dir_contains_only_dotgit(const char *path)
{
DIR *dir = opendir(path);
struct dirent *e;
int ret = 1;
if (!dir)
return 0;
e = readdir_skip_dot_and_dotdot(dir);
if (!e)
ret = 0;
else if (strcmp(DEFAULT_GIT_DIR_ENVIRONMENT, e->d_name) ||
(e = readdir_skip_dot_and_dotdot(dir))) {
error("unexpected item '%s' in '%s'", e->d_name, path);
ret = 0;
}
closedir(dir);
return ret;
}
static int clone_submodule(const struct module_clone_data *clone_data,
struct string_list *reference)
{
char *p;
char *sm_gitdir = clone_submodule_sm_gitdir(clone_data->name);
char *sm_alternate = NULL, *error_strategy = NULL;
struct stat st;
struct child_process cp = CHILD_PROCESS_INIT;
const char *clone_data_path = clone_data->path;
char *to_free = NULL;
@ -1660,6 +1683,10 @@ static int clone_submodule(const struct module_clone_data *clone_data,
"git dir"), sm_gitdir);
if (!file_exists(sm_gitdir)) {
if (clone_data->require_init && !stat(clone_data_path, &st) &&
!is_empty_dir(clone_data_path))
die(_("directory not empty: '%s'"), clone_data_path);
if (safe_create_leading_directories_const(sm_gitdir) < 0)
die(_("could not create directory '%s'"), sm_gitdir);
@ -1704,6 +1731,14 @@ static int clone_submodule(const struct module_clone_data *clone_data,
if(run_command(&cp))
die(_("clone of '%s' into submodule path '%s' failed"),
clone_data->url, clone_data_path);
if (clone_data->require_init && !stat(clone_data_path, &st) &&
!dir_contains_only_dotgit(clone_data_path)) {
char *dot_git = xstrfmt("%s/.git", clone_data_path);
unlink(dot_git);
free(dot_git);
die(_("directory not empty: '%s'"), clone_data_path);
}
} else {
char *path;

48
t/t7406-submodule-update.sh
View File

@ -1179,4 +1179,52 @@ test_expect_success 'submodule update --recursive skip submodules with strategy=
test_cmp expect.err actual.err
'
test_expect_success CASE_INSENSITIVE_FS,SYMLINKS \
'submodule paths must not follow symlinks' '
# This is only needed because we want to run this in a self-contained
# test without having to spin up an HTTP server; However, it would not
# be needed in a real-world scenario where the submodule is simply
# hosted on a public site.
test_config_global protocol.file.allow always &&
# Make sure that Git tries to use symlinks on Windows
test_config_global core.symlinks true &&
tell_tale_path="$PWD/tell.tale" &&
git init hook &&
(
cd hook &&
mkdir -p y/hooks &&
write_script y/hooks/post-checkout <<-EOF &&
echo HOOK-RUN >&2
echo hook-run >"$tell_tale_path"
EOF
git add y/hooks/post-checkout &&
test_tick &&
git commit -m post-checkout
) &&
hook_repo_path="$(pwd)/hook" &&
git init captain &&
(
cd captain &&
git submodule add --name x/y "$hook_repo_path" A/modules/x &&
test_tick &&
git commit -m add-submodule &&
printf .git >dotgit.txt &&
git hash-object -w --stdin <dotgit.txt >dot-git.hash &&
printf "120000 %s 0\ta\n" "$(cat dot-git.hash)" >index.info &&
git update-index --index-info <index.info &&
test_tick &&
git commit -m add-symlink
) &&
test_path_is_missing "$tell_tale_path" &&
test_must_fail git clone --recursive captain hooked 2>err &&
grep "directory not empty" err &&
test_path_is_missing "$tell_tale_path"
'
test_done