From patchwork Tue Apr 4 23:48:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glen Choo X-Patchwork-Id: 13201044 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F34EC76188 for ; Tue, 4 Apr 2023 23:48:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236656AbjDDXsr (ORCPT ); Tue, 4 Apr 2023 19:48:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236625AbjDDXsq (ORCPT ); Tue, 4 Apr 2023 19:48:46 -0400 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 346283C1D for ; Tue, 4 Apr 2023 16:48:45 -0700 (PDT) Received: by mail-wm1-x32c.google.com with SMTP id n19-20020a05600c501300b003f064936c3eso195124wmr.0 for ; Tue, 04 Apr 2023 16:48:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680652123; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :message-id:from:to:cc:subject:date:message-id:reply-to; bh=mSx7z/4fjJNqKjf3NEmaHak5bBBiC8nBj4iFJZ+QAO8=; b=aImoLTyjQQFzmkeZVkh+sRSs1MWgrZmCCXMhPfcwonXkVDbGK7dPVph5uPKaikx3dk Gm0DstbBaBmPCPqARzwSOOyMQHJ0lWTU8HCKEmJsYQnrsEdnBi91WD++uBKQsMtgk32Z jSpduQKI6T8+/+jrGeqWvwe7xLIjQc+z33zFQYVoy5acq/sFyKvdpKUrgoruE+F1SzuQ DL7pdMe9TjUVmW0Lbe/lClYH5IP97XUS313TbgXFszJcrZbiH+ik9EC7fQIU+2u+f1Na F7tt2LcVj95fEpB49A5i2WtWWhFKdzKBeq2qFGEkR1jKUL3L2HqeRWLnsWbRlZYsnd+L 0SDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680652123; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=mSx7z/4fjJNqKjf3NEmaHak5bBBiC8nBj4iFJZ+QAO8=; b=uw76WKmxVH0eEGPQGNUF+iDeY8HXggSdlzVnlzasCPc5IPV6E7WGa5OAf4uNnzjEhs otN3SrA36FeZIRPRHQdDzNMJE+/rkZX4hJvYmGfZOigOsqqqco7uIOhwWzFcD4FHJ3ng YLHgwmoh47UeCdbi/iFYLwayomHnGWFAeGBWYjHZoXnsV6XqUKS5xHAAJzgrM5eW4+xe dYXqYSn9zy0Q6OZHVfzHgIC0VtIWCWJzQ2q9LkH9PCNqj4t2jNtJ8DIUJYdyV2Q2tz3S 1HjUMupVJ0gd99ga2oCxkmDHDsWH3ocS5ZqTFp+js1+j3FH2M7AqbRz8kT4EEo/W23+H IDyQ== X-Gm-Message-State: AAQBX9diYK1OqaTxpJTfb9F0OXqVmIikCAh/PnRV1xfkhf2LHSzk8xuo HjgVThq+OfGaK8umGoqsfGoqY92/SRM= X-Google-Smtp-Source: AKy350ZGOOanRLrUaAR79kwEBkD1U9j6hhGxRIoRIiR0yfHL70p3ZR9/6N3HX8OyiKp5Xm5KdxMS+A== X-Received: by 2002:a7b:c850:0:b0:3ef:6ea4:a675 with SMTP id c16-20020a7bc850000000b003ef6ea4a675mr3209257wml.36.1680652123206; Tue, 04 Apr 2023 16:48:43 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id q25-20020a7bce99000000b003edc11c2ecbsm379946wmj.4.2023.04.04.16.48.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Apr 2023 16:48:42 -0700 (PDT) Message-Id: Date: Tue, 04 Apr 2023 23:48:42 +0000 Subject: [PATCH] clone: error specifically with --local and symlinked objects Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo 6f054f9fb3 (builtin/clone.c: disallow --local clones with symlinks, 2022-07-28) gives a good error message when "git clone --local" fails when the repo to clone has symlinks in "$GIT_DIR/objects". In bffc762f87 (dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS, 2023-01-24), we later extended this restriction to the case where "$GIT_DIR/objects" is itself a symlink, but we didn't update the error message then - bffc762f87's tests show that we print a generic "failed to start iterator over" message. This is exacerbated by the fact that Documentation/git-clone.txt mentions neither restriction, so users are left wondering if this is intentional behavior or not. Fix this by adding a check to builtin/clone.c: when doing a local clone, perform an extra check to see if "$GIT_DIR/objects" is a symlink, and if so, assume that that was the reason for the failure and report the relevant information. Ideally, dir_iterator_begin() would tell us that the real failure reason is the presence of the symlink, but (as far as I can tell) there isn't an appropriate errno value for that. Also, update Documentation/git-clone.txt to reflect that this restriction exists. Signed-off-by: Glen Choo --- clone: error specifically with --local and symlinked objects We noticed this because repo [1] creates Git repos where "$GIT_DIR/objects" is a symlink, and users have gotten confused as to whether this was intended behavior or not. I'm no good with lstat() and errno, so if there's a better to do this, I'd appreciate the input :) [1] https://gerrit.googlesource.com/git-repo Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1488%2Fchooglen%2Fpush-nymnqqnttzxz-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1488/chooglen/push-nymnqqnttzxz-v1 Pull-Request: https://github.com/git/git/pull/1488 Documentation/git-clone.txt | 5 +++++ builtin/clone.c | 7 ++++++- t/t5604-clone-reference.sh | 2 +- 3 files changed, 12 insertions(+), 2 deletions(-) base-commit: 27d43aaaf50ef0ae014b88bba294f93658016a2e diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt index d6434d262d6..c37c4a37f74 100644 --- a/Documentation/git-clone.txt +++ b/Documentation/git-clone.txt @@ -58,6 +58,11 @@ never use the local optimizations). Specifying `--no-local` will override the default when `/path/to/repo` is given, using the regular Git transport instead. + +If the repository's `$GIT_DIR/objects` has symbolic links or is a +symbolic link, the clone will fail. This is a security measure to +prevent the unintentional copying of files by dereferencing the symbolic +links. ++ *NOTE*: this operation can race with concurrent modification to the source repository, similar to running `cp -r src dst` while modifying `src`. diff --git a/builtin/clone.c b/builtin/clone.c index 462c286274c..74ec5b8b02a 100644 --- a/builtin/clone.c +++ b/builtin/clone.c @@ -327,8 +327,13 @@ static void copy_or_link_directory(struct strbuf *src, struct strbuf *dest, iter = dir_iterator_begin(src->buf, DIR_ITERATOR_PEDANTIC); - if (!iter) + if (!iter) { + struct stat st; + if (lstat(src->buf, &st) >= 0 && S_ISLNK(st.st_mode)) + die(_("'%s' is a symlink, refusing to clone with --local"), + src->buf); die_errno(_("failed to start iterator over '%s'"), src->buf); + } strbuf_addch(src, '/'); src_len = src->len; diff --git a/t/t5604-clone-reference.sh b/t/t5604-clone-reference.sh index 83e3c97861d..9845fc04d59 100755 --- a/t/t5604-clone-reference.sh +++ b/t/t5604-clone-reference.sh @@ -358,7 +358,7 @@ test_expect_success SYMLINKS 'clone repo with symlinked objects directory' ' test_must_fail git clone --local malicious clone 2>err && test_path_is_missing clone && - grep "failed to start iterator over" err + grep "is a symlink, refusing to clone with --local" err ' test_done