Merge pull request libgit2#6349 from libgit2/ethomson/cve-2022-29187

Fixes for CVE 2022-29187

Author: ethomson

src/libgit2/repository.c

@@ -488,60 +488,110 @@ static int read_gitfile(git_str *path_out, const char *file_path)
 typedef struct {
 	const char *repo_path;
 	git_str tmp;
-	bool is_safe;
+	bool *is_safe;
 } validate_ownership_data;
 
 static int validate_ownership_cb(const git_config_entry *entry, void *payload)
 {
 	validate_ownership_data *data = payload;
 
 	if (strcmp(entry->value, "") == 0)
-		data->is_safe = false;
+		*data->is_safe = false;
 
 	if (git_fs_path_prettify_dir(&data->tmp, entry->value, NULL) == 0 &&
 	    strcmp(data->tmp.ptr, data->repo_path) == 0)
-		data->is_safe = true;
+		*data->is_safe = true;
 
 	return 0;
 }
 
-static int validate_ownership(const char *repo_path)
+static int validate_ownership_config(bool *is_safe, const char *path)
 {
-	git_config *config = NULL;
-	validate_ownership_data data = { repo_path, GIT_STR_INIT, false };
-	git_fs_path_owner_t owner_level =
-		GIT_FS_PATH_OWNER_CURRENT_USER |
-		GIT_FS_PATH_USER_IS_ADMINISTRATOR;
-	bool is_safe;
+	validate_ownership_data ownership_data = {
+		path, GIT_STR_INIT, is_safe
+	};
+	git_config *config;
 	int error;
 
-	if ((error = git_fs_path_owner_is(&is_safe, repo_path, owner_level)) < 0) {
-		if (error == GIT_ENOTFOUND)
-			error = 0;
+	if (load_global_config(&config) != 0)
+		return 0;
 
-		goto done;
-	}
+	error = git_config_get_multivar_foreach(config,
+		"safe.directory", NULL,
+		validate_ownership_cb,
+		&ownership_data);
+
+	git_config_free(config);
+	git_str_dispose(&ownership_data.tmp);
 
-	if (is_safe) {
+	return error;
+}
+
+static int validate_ownership_path(bool *is_safe, const char *path)
+{
+	git_fs_path_owner_t owner_level =
+		GIT_FS_PATH_OWNER_CURRENT_USER |
+		GIT_FS_PATH_USER_IS_ADMINISTRATOR |
+		GIT_FS_PATH_OWNER_RUNNING_SUDO;
+	int error = 0;
+
+	if (path)
+		error = git_fs_path_owner_is(is_safe, path, owner_level);
+
+	if (error == GIT_ENOTFOUND) {
+		*is_safe = true;
 		error = 0;
-		goto done;
 	}
 
-	if (load_global_config(&config) == 0) {
-		error = git_config_get_multivar_foreach(config, "safe.directory", NULL, validate_ownership_cb, &data);
+	return error;
+}
+
+static int validate_ownership(git_repository *repo)
+{
+	const char *validation_paths[3] = { NULL }, *path;
+	size_t validation_len = 0, i;
+	bool is_safe = false;
+	int error = 0;
+
+	/*
+	 * If there's a worktree, validate the permissions to it *and*
+	 * the git directory, and use the worktree as the configuration
+	 * key for allowlisting the directory. In a bare setup, only
+	 * look at the gitdir and use that as the allowlist. So we
+	 * examine all `validation_paths` but use only the first as
+	 * the configuration lookup.
+	 */
+
+	if (repo->workdir)
+		validation_paths[validation_len++] = repo->workdir;
 
-		if (!error && data.is_safe)
+	if (repo->gitlink)
+		validation_paths[validation_len++] = repo->gitlink;
+
+	validation_paths[validation_len++] = repo->gitdir;
+
+	for (i = 0; i < validation_len; i++) {
+		path = validation_paths[i];
+
+		if ((error = validate_ownership_path(&is_safe, path)) < 0)
 			goto done;
+
+		if (!is_safe)
+			break;
 	}
 
-	git_error_set(GIT_ERROR_CONFIG,
-		"repository path '%s' is not owned by current user",
-		repo_path);
-	error = GIT_EOWNER;
+	if (is_safe ||
+	    (error = validate_ownership_config(&is_safe, validation_paths[0])) < 0)
+		goto done;
+
+	if (!is_safe) {
+		git_error_set(GIT_ERROR_CONFIG,
+			"repository path '%s' is not owned by current user",
+			path);
+		error = GIT_EOWNER;
+	}
 
 done:
-	git_config_free(config);
-	git_str_dispose(&data.tmp);
 	return error;
 }
 
@@ -918,7 +968,6 @@ int git_repository_open_ext(
 		gitlink = GIT_STR_INIT, commondir = GIT_STR_INIT;
 	git_repository *repo = NULL;
 	git_config *config = NULL;
-	const char *validation_path;
 	int version = 0;
 
 	if (flags & GIT_REPOSITORY_OPEN_FROM_ENV)
@@ -977,12 +1026,11 @@ int git_repository_open_ext(
 	}
 
 	/*
-	 * Ensure that the git directory is owned by the current user.
+	 * Ensure that the git directory and worktree are
+	 * owned by the current user.
 	 */
-	validation_path = repo->is_bare ? repo->gitdir : repo->workdir;
-
 	if (git_repository__validate_ownership &&
-	    (error = validate_ownership(validation_path)) < 0)
+	    (error = validate_ownership(repo)) < 0)
 		goto cleanup;
 
 cleanup:

src/util/fs_path.c

@@ -1934,27 +1934,36 @@ int git_fs_path_owner_is(
 
 #else
 
+static int sudo_uid_lookup(uid_t *out)
+{
+	git_str uid_str = GIT_STR_INIT;
+	int64_t uid;
+	int error;
+
+	if ((error = git__getenv(&uid_str, "SUDO_UID")) == 0 &&
+	    (error = git__strntol64(&uid, uid_str.ptr, uid_str.size, NULL, 10)) == 0 &&
+	    uid == (int64_t)((uid_t)uid)) {
+		*out = (uid_t)uid;
+	}
+
+	git_str_dispose(&uid_str);
+	return error;
+}
+
 int git_fs_path_owner_is(
 	bool *out,
 	const char *path,
 	git_fs_path_owner_t owner_type)
 {
-	uid_t uids[2] = { 0 };
-	size_t uid_count = 0, i;
 	struct stat st;
+	uid_t euid, sudo_uid;
 
 	if (mock_owner) {
 		*out = ((mock_owner & owner_type) != 0);
 		return 0;
 	}
 
-	if (owner_type & GIT_FS_PATH_OWNER_CURRENT_USER)
-		uids[uid_count++] = geteuid();
-
-	if (owner_type & GIT_FS_PATH_OWNER_ADMINISTRATOR)
-		uids[uid_count++] = 0;
-
-	*out = false;
+	euid = geteuid();
 
 	if (p_lstat(path, &st) != 0) {
 		if (errno == ENOENT)
@@ -1964,13 +1973,27 @@ int git_fs_path_owner_is(
 		return -1;
 	}
 
-	for (i = 0; i < uid_count; i++) {
-		if (uids[i] == st.st_uid) {
-			*out = true;
-			break;
-		}
+	if ((owner_type & GIT_FS_PATH_OWNER_CURRENT_USER) != 0 &&
+	    st.st_uid == euid) {
+		*out = true;
+		return 0;
+	}
+
+	if ((owner_type & GIT_FS_PATH_OWNER_ADMINISTRATOR) != 0 &&
+	    st.st_uid == 0) {
+		*out = true;
+		return 0;
+	}
+
+	if ((owner_type & GIT_FS_PATH_OWNER_RUNNING_SUDO) != 0 &&
+	    euid == 0 &&
+	    sudo_uid_lookup(&sudo_uid) == 0 &&
+	    st.st_uid == sudo_uid) {
+		*out = true;
+		return 0;
 	}
 
+	*out = false;
 	return 0;
 }
 

src/util/fs_path.h

@@ -747,8 +747,13 @@ typedef enum {
 	 */
 	GIT_FS_PATH_USER_IS_ADMINISTRATOR = (1 << 2),
 
+	/**
+	 * The file is owned by the current user, who is running `sudo`.
+	 */
+	GIT_FS_PATH_OWNER_RUNNING_SUDO = (1 << 3),
+
 	/** The file may be owned by another user. */
-	GIT_FS_PATH_OWNER_OTHER = (1 << 3)
+	GIT_FS_PATH_OWNER_OTHER = (1 << 4)
 } git_fs_path_owner_t;
 
 /**