From patchwork Mon Jun 27 18:36:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glen Choo X-Patchwork-Id: 12896997 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 74991CCA473 for ; Mon, 27 Jun 2022 18:38:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240486AbiF0Sik (ORCPT ); Mon, 27 Jun 2022 14:38:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240485AbiF0SiL (ORCPT ); Mon, 27 Jun 2022 14:38:11 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81F53CD7 for ; Mon, 27 Jun 2022 11:36:38 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id e28so9118866wra.0 for ; Mon, 27 Jun 2022 11:36:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=eg9oT2ttxFEF1wkAt+PI0iAiQ436tiumYPH3Aazib7E=; b=D4sW+MuYgf8fBMUS2ECsMpV1HGTAYBjilySFW6tWdR4TpNWMwrNCgJ4iuFKtR3L2ph OM+CACYHmQrv7bLk3yLdVGeUbjqMnMWQevjlsIuffszBb+9BMvqE03ZKPIrHci211dmz 7mC5QIodWdafs60t9SEcnzHd35D8oSxmVT7p5W+uNAlOg7kzM8CBygxwqWtyrUTVwc68 QRVHdh4hJzQnwmGTSBRpVPHICs7U09sxBhMeYwuifghbLl0VNfhI4/I5kzYWCiCtVhNH Tqiwz+3GqzgQJnp2/W8lb3FW7pOgo8Fv0mEq62JUuTeJHeHf+GTbNfiTtqbPQvHNamDP cElw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=eg9oT2ttxFEF1wkAt+PI0iAiQ436tiumYPH3Aazib7E=; b=p1R+b3Z/SYfBWD6aA0mekq+aT33qi8yiKK7OGZ0ndIvacHGoEKl4E0HXVBkDcOaFi2 LAno597xCkDc/Trt9f7BX4YxKtapyp1eb0N15OarOLMkiF/LfAYpJMw2JQqSS6YtngZU seZ0Qyk2BpN1GdUdU+wWo+8UgR0EEH4JxDWBA5KfSKsHKfJhE1HL3L8VIQjgd3y5luvl eCj+rbah3R8d/eDjQf5XnRtrNJWqrBOBN0RRhjm1I7OWVi7AynlhI8uKMUMgwpzsk4ZM 23T1ASeDPpc5c9jMwd/EEc8Wu+G21fIx7ZsIFA4SqTf4BbZCG69XEDlUVbD8yVrmICNw EiFw== X-Gm-Message-State: AJIora/FBH2T6MG8T2irOzXTYcY7qHgXyMrep+36oDklW6FTx7mchmJJ 5k6Y2UNCbMwQVHFaVGaQdw4KN017/ubvxg== X-Google-Smtp-Source: AGRyM1tH3hbzActPj7H5RH1wOAPQo9HlX5/TOHkvxvumU+jnk3U52QVL0qB3WicOnrcilVS1yUpB7Q== X-Received: by 2002:a5d:6d45:0:b0:21a:2f43:cb76 with SMTP id k5-20020a5d6d45000000b0021a2f43cb76mr13842982wri.254.1656354996790; Mon, 27 Jun 2022 11:36:36 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id h4-20020a5d4304000000b0021b829d111csm11530943wrq.112.2022.06.27.11.36.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 11:36:35 -0700 (PDT) Message-Id: In-Reply-To: References: Date: Mon, 27 Jun 2022 18:36:30 +0000 Subject: [PATCH v5 1/5] Documentation/git-config.txt: add SCOPES section Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , "brian m. carlson" , Derrick Stolee , Junio C Hamano , Emily Shaffer , Jonathan Tan , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo In a subsequent commit, we will introduce "protected configuration", which is easiest to describe in terms of configuration scopes (i.e. it's the union of the 'system', 'global', and 'command' scopes). This description is fine for ML discussions, but it's inadequate for end users because we don't provide a good description of "configuration scopes" in the public docs. 145d59f482 (config: add '--show-scope' to print the scope of a config value, 2020-02-10) introduced the word "scope" to our public docs, but that only enumerates the scopes and assumes the user can figure out those values mean. Add a SCOPES section to Documentation/git-config.txt that describes the configuration scopes, their corresponding CLI options, and mentions that some configuration options are only respected in certain scopes. Then, use the word "scope" to simplify the FILES section and change some confusing wording. Signed-off-by: Glen Choo --- Documentation/git-config.txt | 64 ++++++++++++++++++++++++++++-------- 1 file changed, 50 insertions(+), 14 deletions(-) diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt index 9376e39aef2..f93d437b898 100644 --- a/Documentation/git-config.txt +++ b/Documentation/git-config.txt @@ -297,8 +297,8 @@ The default is to use a pager. FILES ----- -If not set explicitly with `--file`, there are four files where -'git config' will search for configuration options: +By default, 'git config' will read configuration options from multiple +files: $(prefix)/etc/gitconfig:: System-wide configuration file. @@ -322,27 +322,63 @@ $GIT_DIR/config.worktree:: This is optional and is only searched when `extensions.worktreeConfig` is present in $GIT_DIR/config. -If no further options are given, all reading options will read all of these -files that are available. If the global or the system-wide configuration -file are not available they will be ignored. If the repository configuration -file is not available or readable, 'git config' will exit with a non-zero -error code. However, in neither case will an error message be issued. +You may also provide additional configuration parameters when running any +git command by using the `-c` option. See linkgit:git[1] for details. + +Options will be read from all of these files that are available. If the +global or the system-wide configuration file are not available they will be +ignored. If the repository configuration file is not available or readable, +'git config' will exit with a non-zero error code. However, in neither case +will an error message be issued. The files are read in the order given above, with last value found taking precedence over values read earlier. When multiple values are taken then all values of a key from all files will be used. -You may override individual configuration parameters when running any git -command by using the `-c` option. See linkgit:git[1] for details. - -All writing options will per default write to the repository specific +By default, options are only written to the repository specific configuration file. Note that this also affects options like `--replace-all` and `--unset`. *'git config' will only ever change one file at a time*. -You can override these rules using the `--global`, `--system`, -`--local`, `--worktree`, and `--file` command-line options; see -<> above. +You can change the way options are read/written by specifying the path to a +file (`--file`), or by specifying a configuration scope (`--system`, +`--global`, `--local`, `--worktree`); see <> above. + +SCOPES +------ + +Each configuration source falls within a configuration scope. The scopes +are: + +system:: + $(prefix)/etc/gitconfig + +global:: + $XDG_CONFIG_HOME/git/config ++ +~/.gitconfig + +local:: + $GIT_DIR/config + +worktree:: + $GIT_DIR/config.worktree + +command:: + environment variables ++ +the `-c` option + +With the exception of 'command', each scope corresponds to a command line +option - `--system`, `--global`, `--local`, `--worktree`. + +When reading options, specifying a scope will only read options from the +files within that scope. When writing options, specifying a scope will write +to the files within that scope (instead of the repository specific +configuration file). See <> above for a complete description. +Most configuration options are respected regardless of the scope it is +defined in, but some options are only respected in certain scopes. See the +option's documentation for the full details. ENVIRONMENT ----------- From patchwork Mon Jun 27 18:36:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glen Choo X-Patchwork-Id: 12896992 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 9E092C43334 for ; Mon, 27 Jun 2022 18:38:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240570AbiF0Sia (ORCPT ); Mon, 27 Jun 2022 14:38:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240490AbiF0SiL (ORCPT ); Mon, 27 Jun 2022 14:38:11 -0400 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1C08CD8 for ; Mon, 27 Jun 2022 11:36:39 -0700 (PDT) Received: by mail-wr1-x42c.google.com with SMTP id s1so14263622wra.9 for ; Mon, 27 Jun 2022 11:36:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=gTcS6gAx+mAwu67s0Vsrg+OViPFhCGZSE7su0s70T3I=; b=TI2tEdfvjmjGZgtGnbX7CZ4kgySUmV75akglW05ipTLlBdDjNgiXhegE6jnxUqa9nC jq1faVjB/HYgljSvZKoVJ6QTPwulZM5VLWBEd+Ar69zZ8vaQuEYvH9rOPvAoancJCHTS q/BsIB7M+nvD1aF7v7caDrGftmjtLfRXFllcE1zE7t4jDBr90O5hbFxbCaUpSFYZqBoU qVpZynWzQuUh3w9rqZhYn3oaoh+qDrdo+AmP69IanSdKfLFW/i36nMDqil9AMmV/QllI uyDGyc55EgFLQHwbHEEeB7cTOkejoxDtw7yCdSH4Z+Ugjne7F+J44q2+vSy33RUKg7uu zvlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=gTcS6gAx+mAwu67s0Vsrg+OViPFhCGZSE7su0s70T3I=; b=ImHhPpkYFld/YjROduu+rPB/AP9e3QT8W8eUuz8OIO5Hs5mQty9nCCxsXMb4zt/mGT kqjglmCMDEl667biEmVSAVN6BmP4SHztKF+d9jeB1uIvwyRBBRR/u5Xczhnm0/B77Y34 BCzRak0DUXltodifl9P7CnUWtxJA8DOVbZWEqSdipg5iowND2yJYrcoVHVS3mfDNyXdP vOiHszY2o41eBofsHUrSEHS/7KQu3gAL2qzNSPv6ibDJHnpezFTLLNItIvQZgqa/Og/7 Qt+LSJ/GfLeK/YQZC/7R7es7tbD/tjTqaJEDCTxMXyLfF7Nv3GFrbFxobEftMa2sm7qW Pf6A== X-Gm-Message-State: AJIora9u3YXu9ojc5Yah1sN4WOyXfj5rlFXbycAW8AU6hVmGZ42fcSTv ewuw0yhS4OGsAKlpc04FcY3964QypQZz2g== X-Google-Smtp-Source: AGRyM1uYxxwE9kiNVdzuhtntdPJFH8ygPvV5uLiwE3zfogwrAQnfsq9JEuUxoWu4V2GbXeVhAn5aFw== X-Received: by 2002:a5d:584e:0:b0:21c:ea0c:3746 with SMTP id i14-20020a5d584e000000b0021cea0c3746mr5474337wrf.199.1656354998016; Mon, 27 Jun 2022 11:36:38 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id n12-20020a5d6b8c000000b0020c5253d8fcsm13335303wrx.72.2022.06.27.11.36.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 11:36:37 -0700 (PDT) Message-Id: <43627c05c0b997ea407c865b04994cba630297d6.1656354994.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Mon, 27 Jun 2022 18:36:31 +0000 Subject: [PATCH v5 2/5] Documentation: define protected configuration Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , "brian m. carlson" , Derrick Stolee , Junio C Hamano , Emily Shaffer , Jonathan Tan , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo For security reasons, there are config variables that are only trusted when they are specified in certain configuration scopes, which are sometimes referred to on-list as 'protected configuration' [1]. A future commit will introduce another such variable, so let's define our terms so that we can have consistent documentation and implementation. In our documentation, define 'protected configuration' as the system, global and command config scopes. As a shorthand, I will refer to variables that are only respected in protected config as 'protected configuration only', but this term is not used in the documentation. This definition of protected config is based on whether or not Git can reasonably protect the user by ignoring the configuration scope: - System, global and command line config are considered protected because an attacker who has control over any of those can do plenty of harm without Git, so we gain very little by ignoring those scopes. - On the other hand, local (and similarly, worktree) config are not considered protected because it is relatively easy for an attacker to control local config, e.g.: - On some shared user environments, a non-admin attacker can create a repository high up the directory hierarchy (e.g. C:\.git on Windows), and a user may accidentally use it when their PS1 automatically invokes "git" commands. `safe.directory` prevents attacks of this form by making sure that the user intended to use the shared repository. It obviously shouldn't be read from the repository, because that would end up trusting the repository that Git was supposed to reject. - "git upload-pack" is expected to run in repositories that may not be controlled by the user. We cannot ignore all config in that repository (because "git upload-pack" would fail), but we can limit the risks by ignoring `uploadpack.packObjectsHook`. Only `uploadpack.packObjectsHook` is 'protected configuration only'. The following variables are intentionally excluded: - `safe.directory` should be 'protected configuration only', but it does not technically fit the definition because it is not respected in the "command" scope. A future commit will fix this. - `trace2.*` happens to read the same scopes as `safe.directory` because they share an implementation. However, this is not for security reasons; it is because we want to start tracing so early that repository-level config and "-c" are not available [2]. This requirement is unique to `trace2.*`, so it does not makes sense for protected configuration to be subject to the same constraints. [1] For example, https://lore.kernel.org/git/6af83767-576b-75c4-c778-0284344a8fe7@github.com/ [2] https://lore.kernel.org/git/a0c89d0d-669e-bf56-25d2-cbb09b012e70@jeffhostetler.com/ Signed-off-by: Glen Choo --- Documentation/config/uploadpack.txt | 6 +++--- Documentation/git-config.txt | 13 +++++++++++++ 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/Documentation/config/uploadpack.txt b/Documentation/config/uploadpack.txt index 32fad5bbe81..029abbefdff 100644 --- a/Documentation/config/uploadpack.txt +++ b/Documentation/config/uploadpack.txt @@ -49,9 +49,9 @@ uploadpack.packObjectsHook:: `pack-objects` to the hook, and expects a completed packfile on stdout. + -Note that this configuration variable is ignored if it is seen in the -repository-level config (this is a safety measure against fetching from -untrusted repositories). +Note that this configuration variable is only respected when it is specified +in protected config (see <>). This is a safety measure against +fetching from untrusted repositories. uploadpack.allowFilter:: If this option is set, `upload-pack` will support partial diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt index f93d437b898..f1810952891 100644 --- a/Documentation/git-config.txt +++ b/Documentation/git-config.txt @@ -343,6 +343,7 @@ You can change the way options are read/written by specifying the path to a file (`--file`), or by specifying a configuration scope (`--system`, `--global`, `--local`, `--worktree`); see <> above. +[[SCOPES]] SCOPES ------ @@ -380,6 +381,18 @@ Most configuration options are respected regardless of the scope it is defined in, but some options are only respected in certain scopes. See the option's documentation for the full details. +Protected configuration +~~~~~~~~~~~~~~~~~~~~~~~ + +Protected configuration refers to the 'system', 'global', and 'command' scopes. +For security reasons, certain options are only respected when they are +specified in protected configuration, and ignored otherwise. + +Git treats these scopes as if they are controlled by the user or a trusted +administrator. This is because an attacker who controls these scopes can do +substantial harm without using Git, so it is assumed that the user's environment +protects these scopes against attackers. + ENVIRONMENT ----------- From patchwork Mon Jun 27 18:36:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glen Choo X-Patchwork-Id: 12896994 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 76EFEC433EF for ; Mon, 27 Jun 2022 18:38:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237017AbiF0Sig (ORCPT ); Mon, 27 Jun 2022 14:38:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240492AbiF0SiL (ORCPT ); Mon, 27 Jun 2022 14:38:11 -0400 Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2888CE1 for ; Mon, 27 Jun 2022 11:36:40 -0700 (PDT) Received: by mail-wm1-x32a.google.com with SMTP id o19-20020a05600c4fd300b003a0489f414cso2630719wmq.4 for ; Mon, 27 Jun 2022 11:36:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=BuAOV0ZU7Afp2grKZb5gtV5C/rUTELHJYczDClikMtA=; b=PHzKUav9KVm/INunQ4MHLN1oM1XXAgbqOkD/XDLNIa2O78NDYohPLAu+KemYM9n0f1 +QGvhu6Dv0YeMwuYy0TpRNG01e2NX2AdfZZM4btzFlDU1FlVXsz8V7BXmiVKqy+UWP9/ WSZEdZ/m7YkTrWBqYCa8SOPjWgiRDGiVJ3ZWjL3GhEAzfnWkPObSX8dtM9htsS1LykXu RZkuFOQ3JjTy6Ei7VgsbBlQ6r19fy9mmUeBgaKHnULwXOLQ2eZ4itUp9cgEIFM+SDqjw RBNphW5ZjWLrbYK4olDsH0i/VS/EeJJ7AT+8WRcW1X8+YI/WQu0pY5jtoU2qkB5o3LHb j9Ng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=BuAOV0ZU7Afp2grKZb5gtV5C/rUTELHJYczDClikMtA=; b=NAHbJwN5Ple22IrjQe9knr7NRW//XdGNJeB/vncSNxt/hqsHyB9F4IoYlmU7SS1zLr xgHu3Fn23beGmR1YyFsxgFaFhGY15iVuM5Avm460OjEDMhWfr1XigiSkTSeVohVWus5A UGBxV4DZ2qrY5sB3E2wICxnx/ftnX7iQa3EOoPh6A46bwb0QpdtfwqB+kZykewR19M9g ZxbT9pp1cJ/E+BDzOVUN98wPfqATqEmRb9qFI8AfOkS/VVoDI5PyuDLbyQV2QVyku6q3 NqwGBVb6IPE/KUXABsJPpLybRWlzJnpOmBWuAMxspvxAdqngTtVT3EgjXT+RNghNrP/M DSVw== X-Gm-Message-State: AJIora/EkQXXi+le7NekcAfST5FawX1MjkOBYJTnMCIZnyIqd2I+qc4/ d7l2N8bTGqGZr2EZx9CkW0mch06sV7YIAQ== X-Google-Smtp-Source: AGRyM1vpWWLRCuxDEaEjGOz30/K35PFoJyGgvNGM8zFss9Mi1fpXrGCZwiiaObpm6FeucLYztv26pQ== X-Received: by 2002:a05:600c:1e14:b0:3a0:2bba:4b2e with SMTP id ay20-20020a05600c1e1400b003a02bba4b2emr17285087wmb.196.1656354999129; Mon, 27 Jun 2022 11:36:39 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id w13-20020a5d680d000000b0021b93a483dbsm11227084wru.32.2022.06.27.11.36.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 11:36:38 -0700 (PDT) Message-Id: <3efe282e6b94c3daed77590c5f601fad34137c9c.1656354994.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Mon, 27 Jun 2022 18:36:32 +0000 Subject: [PATCH v5 3/5] config: learn `git_protected_config()` Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , "brian m. carlson" , Derrick Stolee , Junio C Hamano , Emily Shaffer , Jonathan Tan , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo `uploadpack.packObjectsHook` is the only 'protected configuration only' variable today, but we've noted that `safe.directory` and the upcoming `discovery.bare` should also be 'protected configuration only'. So, for consistency, we'd like to have a single implementation for protected config. The primary constraints are: 1. Reading from protected configuration should be as fast as possible. Nearly all "git" commands inside a bare repository will read both `safe.directory` and `discovery.bare`, so we cannot afford to be slow. 2. Protected config must be readable when the gitdir is not known. `safe.directory` and `discovery.bare` both affect repository discovery and the gitdir is not known at that point [1]. The chosen implementation in this commit is to read protected configuration and cache the values in a global configset. This is similar to the caching behavior we get with the_repository->config. Introduce git_protected_config(), which reads protected configuration and caches them in the global configset protected_config. Then, refactor `uploadpack.packObjectsHook` to use git_protected_config(). The protected configuration functions are named similarly to their non-protected counterparts, e.g. git_protected_config_check_init() vs git_config_check_init(). In light of constraint 1, this implementation can still be improved since git_protected_config() iterates through every variable in protected_config, which may still be too expensive. There exist constant time lookup functions for non-protected configuration (repo_config_get_*()), but for simplicity, this commit does not implement similar functions for protected configuration. An alternative that avoids introducing another configset is to continue to read all config using git_config(), but only accept values that have the correct config scope [2]. This technically fulfills constraint 2, because git_config() simply ignores the local and worktree config when the gitdir is not known. However, this would read incomplete config into the_repository->config, which would need to be reset when the gitdir is known and git_config() needs to read the local and worktree config. Resetting the_repository->config might be reasonable while we only have these 'protected configuration only' variables, but it's not clear whether this extends well to future variables. [1] In this case, we do have a candidate gitdir though, so with a little refactoring, it might be possible to provide a gitdir. [2] This is how `uploadpack.packObjectsHook` was implemented prior to this commit. Signed-off-by: Glen Choo --- config.c | 51 ++++++++++++++++++++++++++++++++++++ config.h | 17 ++++++++++++ t/t5544-pack-objects-hook.sh | 7 ++++- upload-pack.c | 27 ++++++++++++------- 4 files changed, 91 insertions(+), 11 deletions(-) diff --git a/config.c b/config.c index 9b0e9c93285..29e62f5d0ed 100644 --- a/config.c +++ b/config.c @@ -81,6 +81,18 @@ static enum config_scope current_parsing_scope; static int pack_compression_seen; static int zlib_compression_seen; +/* + * Config that comes from trusted sources, namely: + * - system config files (e.g. /etc/gitconfig) + * - global config files (e.g. $HOME/.gitconfig, + * $XDG_CONFIG_HOME/git) + * - the command line. + * + * This is declared here for code cleanliness, but unlike the other + * static variables, this does not hold config parser state. + */ +static struct config_set protected_config; + static int config_file_fgetc(struct config_source *conf) { return getc_unlocked(conf->u.file); @@ -2378,6 +2390,11 @@ int git_configset_add_file(struct config_set *cs, const char *filename) return git_config_from_file(config_set_callback, filename, cs); } +int git_configset_add_parameters(struct config_set *cs) +{ + return git_config_from_parameters(config_set_callback, cs); +} + int git_configset_get_value(struct config_set *cs, const char *key, const char **value) { const struct string_list *values = NULL; @@ -2619,6 +2636,40 @@ int repo_config_get_pathname(struct repository *repo, return ret; } +/* Read values into protected_config. */ +static void read_protected_config(void) +{ + char *xdg_config = NULL, *user_config = NULL, *system_config = NULL; + + git_configset_init(&protected_config); + + system_config = git_system_config(); + git_global_config(&user_config, &xdg_config); + + git_configset_add_file(&protected_config, system_config); + git_configset_add_file(&protected_config, xdg_config); + git_configset_add_file(&protected_config, user_config); + git_configset_add_parameters(&protected_config); + + free(system_config); + free(xdg_config); + free(user_config); +} + +/* Ensure that protected_config has been initialized. */ +static void git_protected_config_check_init(void) +{ + if (protected_config.hash_initialized) + return; + read_protected_config(); +} + +void git_protected_config(config_fn_t fn, void *data) +{ + git_protected_config_check_init(); + configset_iter(&protected_config, fn, data); +} + /* Functions used historically to read configuration from 'the_repository' */ void git_config(config_fn_t fn, void *data) { diff --git a/config.h b/config.h index 7654f61c634..e3ff1fcf683 100644 --- a/config.h +++ b/config.h @@ -446,6 +446,15 @@ void git_configset_init(struct config_set *cs); */ int git_configset_add_file(struct config_set *cs, const char *filename); +/** + * Parses command line options and environment variables, and adds the + * variable-value pairs to the `config_set`. Returns 0 on success, or -1 + * if there is an error in parsing. The caller decides whether to free + * the incomplete configset or continue using it when the function + * returns -1. + */ +int git_configset_add_parameters(struct config_set *cs); + /** * Finds and returns the value list, sorted in order of increasing priority * for the configuration variable `key` and config set `cs`. When the @@ -505,6 +514,14 @@ int repo_config_get_maybe_bool(struct repository *repo, int repo_config_get_pathname(struct repository *repo, const char *key, const char **dest); +/* + * Functions for reading protected config. By definition, protected + * config ignores repository config, so it is unnecessary to read + * protected config from any `struct repository` other than + * the_repository. + */ +void git_protected_config(config_fn_t fn, void *data); + /** * Querying For Specific Variables * ------------------------------- diff --git a/t/t5544-pack-objects-hook.sh b/t/t5544-pack-objects-hook.sh index dd5f44d986f..54f54f8d2eb 100755 --- a/t/t5544-pack-objects-hook.sh +++ b/t/t5544-pack-objects-hook.sh @@ -56,7 +56,12 @@ test_expect_success 'hook does not run from repo config' ' ! grep "hook running" stderr && test_path_is_missing .git/hook.args && test_path_is_missing .git/hook.stdin && - test_path_is_missing .git/hook.stdout + test_path_is_missing .git/hook.stdout && + + # check that global config is used instead + test_config_global uploadpack.packObjectsHook ./hook && + git clone --no-local . dst2.git 2>stderr && + grep "hook running" stderr ' test_expect_success 'hook works with partial clone' ' diff --git a/upload-pack.c b/upload-pack.c index 3a851b36066..09f48317b02 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -1321,18 +1321,27 @@ static int upload_pack_config(const char *var, const char *value, void *cb_data) data->advertise_sid = git_config_bool(var, value); } - if (current_config_scope() != CONFIG_SCOPE_LOCAL && - current_config_scope() != CONFIG_SCOPE_WORKTREE) { - if (!strcmp("uploadpack.packobjectshook", var)) - return git_config_string(&data->pack_objects_hook, var, value); - } - if (parse_object_filter_config(var, value, data) < 0) return -1; return parse_hide_refs_config(var, value, "uploadpack"); } +static int upload_pack_protected_config(const char *var, const char *value, void *cb_data) +{ + struct upload_pack_data *data = cb_data; + + if (!strcmp("uploadpack.packobjectshook", var)) + return git_config_string(&data->pack_objects_hook, var, value); + return 0; +} + +static void get_upload_pack_config(struct upload_pack_data *data) +{ + git_config(upload_pack_config, data); + git_protected_config(upload_pack_protected_config, data); +} + void upload_pack(const int advertise_refs, const int stateless_rpc, const int timeout) { @@ -1340,8 +1349,7 @@ void upload_pack(const int advertise_refs, const int stateless_rpc, struct upload_pack_data data; upload_pack_data_init(&data); - - git_config(upload_pack_config, &data); + get_upload_pack_config(&data); data.stateless_rpc = stateless_rpc; data.timeout = timeout; @@ -1695,8 +1703,7 @@ int upload_pack_v2(struct repository *r, struct packet_reader *request) upload_pack_data_init(&data); data.use_sideband = LARGE_PACKET_MAX; - - git_config(upload_pack_config, &data); + get_upload_pack_config(&data); while (state != FETCH_DONE) { switch (state) { From patchwork Mon Jun 27 18:36:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glen Choo X-Patchwork-Id: 12896993 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 18E2BC43334 for ; Mon, 27 Jun 2022 18:38:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236476AbiF0Sie (ORCPT ); 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Mon, 27 Jun 2022 11:36:39 -0700 (PDT) Message-Id: In-Reply-To: References: Date: Mon, 27 Jun 2022 18:36:33 +0000 Subject: [PATCH v5 4/5] safe.directory: use git_protected_config() Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , "brian m. carlson" , Derrick Stolee , Junio C Hamano , Emily Shaffer , Jonathan Tan , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo Use git_protected_config() to read `safe.directory` instead of read_very_early_config(), making it 'protected configuration only'. As a result, `safe.directory` now respects "-c", so update the tests and docs accordingly. It used to ignore "-c" due to how it was implemented, not because of security or correctness concerns [1]. [1] https://lore.kernel.org/git/xmqqlevabcsu.fsf@gitster.g/ Signed-off-by: Glen Choo --- Documentation/config/safe.txt | 6 +++--- setup.c | 2 +- t/t0033-safe-directory.sh | 24 ++++++++++-------------- 3 files changed, 14 insertions(+), 18 deletions(-) diff --git a/Documentation/config/safe.txt b/Documentation/config/safe.txt index fa02f3ccc54..f72b4408798 100644 --- a/Documentation/config/safe.txt +++ b/Documentation/config/safe.txt @@ -12,9 +12,9 @@ via `git config --add`. To reset the list of safe directories (e.g. to override any such directories specified in the system config), add a `safe.directory` entry with an empty value. + -This config setting is only respected when specified in a system or global -config, not when it is specified in a repository config, via the command -line option `-c safe.directory=`, or in environment variables. +This config setting is only respected in protected configuration (see +<>). This prevents the untrusted repository from tampering with this +value. + The value of this setting is interpolated, i.e. `~/` expands to a path relative to the home directory and `%(prefix)/` expands to a diff --git a/setup.c b/setup.c index faf5095e44d..c8e3c32814d 100644 --- a/setup.c +++ b/setup.c @@ -1137,7 +1137,7 @@ static int ensure_valid_ownership(const char *path) is_path_owned_by_current_user(path)) return 1; - read_very_early_config(safe_directory_cb, &data); + git_protected_config(safe_directory_cb, &data); return data.is_safe; } diff --git a/t/t0033-safe-directory.sh b/t/t0033-safe-directory.sh index 238b25f91a3..5a1cd0d0947 100755 --- a/t/t0033-safe-directory.sh +++ b/t/t0033-safe-directory.sh @@ -16,24 +16,20 @@ test_expect_success 'safe.directory is not set' ' expect_rejected_dir ' -test_expect_success 'ignoring safe.directory on the command line' ' - test_must_fail git -c safe.directory="$(pwd)" status 2>err && - grep "unsafe repository" err +test_expect_success 'safe.directory on the command line' ' + git -c safe.directory="$(pwd)" status ' -test_expect_success 'ignoring safe.directory in the environment' ' - test_must_fail env GIT_CONFIG_COUNT=1 \ - GIT_CONFIG_KEY_0="safe.directory" \ - GIT_CONFIG_VALUE_0="$(pwd)" \ - git status 2>err && - grep "unsafe repository" err +test_expect_success 'safe.directory in the environment' ' + env GIT_CONFIG_COUNT=1 \ + GIT_CONFIG_KEY_0="safe.directory" \ + GIT_CONFIG_VALUE_0="$(pwd)" \ + git status ' -test_expect_success 'ignoring safe.directory in GIT_CONFIG_PARAMETERS' ' - test_must_fail env \ - GIT_CONFIG_PARAMETERS="${SQ}safe.directory${SQ}=${SQ}$(pwd)${SQ}" \ - git status 2>err && - grep "unsafe repository" err +test_expect_success 'safe.directory in GIT_CONFIG_PARAMETERS' ' + env GIT_CONFIG_PARAMETERS="${SQ}safe.directory${SQ}=${SQ}$(pwd)${SQ}" \ + git status ' test_expect_success 'ignoring safe.directory in repo config' ' From patchwork Mon Jun 27 18:36:34 2022 Content-Type: text/plain; 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Mon, 27 Jun 2022 11:36:41 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id ay4-20020a05600c1e0400b003a047dccfffsm6667120wmb.42.2022.06.27.11.36.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 11:36:41 -0700 (PDT) Message-Id: <14411512783fd4e2cdcc8513690377b29262f6b8.1656354994.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Mon, 27 Jun 2022 18:36:34 +0000 Subject: [PATCH v5 5/5] setup.c: create `discovery.bare` Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , "brian m. carlson" , Derrick Stolee , Junio C Hamano , Emily Shaffer , Jonathan Tan , Glen Choo , Glen Choo Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Glen Choo From: Glen Choo There is a known social engineering attack that takes advantage of the fact that a working tree can include an entire bare repository, including a config file. A user could run a Git command inside the bare repository thinking that the config file of the 'outer' repository would be used, but in reality, the bare repository's config file (which is attacker-controlled) is used, which may result in arbitrary code execution. See [1] for a fuller description and deeper discussion. A simple mitigation is to forbid bare repositories unless specified via `--git-dir` or `GIT_DIR`. In environments that don't use bare repositories, this would be minimally disruptive. Create a config variable, `discovery.bare`, that tells Git whether or not to die() when it discovers a bare repository. This only affects repository discovery, thus it has no effect if discovery was not done, e.g. if the user passes `--git-dir=my-dir`, discovery will be skipped and my-dir will be used as the repo regardless of the `discovery.bare` value. This config is an enum of: - "always": always allow bare repositories (this is the default) - "never": never allow bare repositories If we want to protect users from such attacks by default, neither value will suffice - "always" provides no protection, but "never" is impractical for bare repository users. A more usable default would be to allow only non-embedded bare repositories ([2] contains one such proposal), but detecting if a repository is embedded is potentially non-trivial, so this work is not implemented in this series. [1]: https://lore.kernel.org/git/kl6lsfqpygsj.fsf@chooglen-macbookpro.roam.corp.google.com [2]: https://lore.kernel.org/git/5b969c5e-e802-c447-ad25-6acc0b784582@github.com Signed-off-by: Glen Choo --- Documentation/config.txt | 2 + Documentation/config/discovery.txt | 23 ++++++++++ setup.c | 57 ++++++++++++++++++++++++- t/t0035-discovery-bare.sh | 68 ++++++++++++++++++++++++++++++ 4 files changed, 149 insertions(+), 1 deletion(-) create mode 100644 Documentation/config/discovery.txt create mode 100755 t/t0035-discovery-bare.sh diff --git a/Documentation/config.txt b/Documentation/config.txt index e284b042f22..9a5e1329772 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -409,6 +409,8 @@ include::config/diff.txt[] include::config/difftool.txt[] +include::config/discovery.txt[] + include::config/extensions.txt[] include::config/fastimport.txt[] diff --git a/Documentation/config/discovery.txt b/Documentation/config/discovery.txt new file mode 100644 index 00000000000..bbcf89bb0b5 --- /dev/null +++ b/Documentation/config/discovery.txt @@ -0,0 +1,23 @@ +discovery.bare:: + Specifies whether Git will work with a bare repository that it + found during repository discovery. If the repository is + specified directly via the --git-dir command-line option or the + GIT_DIR environment variable (see linkgit:git[1]), Git will + always use the specified repository, regardless of this value. ++ +This config setting is only respected in protected configuration (see +<>). This prevents the untrusted repository from tampering with +this value. ++ +The currently supported values are: ++ +* `always`: Git always works with bare repositories +* `never`: Git never works with bare repositories ++ +This defaults to `always`, but this default may change in the future. ++ +If you do not use bare repositories in your workflow, then it may be +beneficial to set `discovery.bare` to `never` in your global config. +This will protect you from attacks that involve cloning a repository +that contains a bare repository and running a Git command within that +directory. diff --git a/setup.c b/setup.c index c8e3c32814d..16938fd5a24 100644 --- a/setup.c +++ b/setup.c @@ -10,6 +10,10 @@ static int inside_git_dir = -1; static int inside_work_tree = -1; static int work_tree_config_is_bogus; +enum discovery_bare_allowed { + DISCOVERY_BARE_NEVER = 0, + DISCOVERY_BARE_ALWAYS, +}; static struct startup_info the_startup_info; struct startup_info *startup_info = &the_startup_info; @@ -1142,6 +1146,46 @@ static int ensure_valid_ownership(const char *path) return data.is_safe; } +static int discovery_bare_cb(const char *key, const char *value, void *d) +{ + enum discovery_bare_allowed *discovery_bare_allowed = d; + + if (strcmp(key, "discovery.bare")) + return 0; + + if (!strcmp(value, "never")) { + *discovery_bare_allowed = DISCOVERY_BARE_NEVER; + return 0; + } + if (!strcmp(value, "always")) { + *discovery_bare_allowed = DISCOVERY_BARE_ALWAYS; + return 0; + } + return -1; +} + +static enum discovery_bare_allowed get_discovery_bare(void) +{ + enum discovery_bare_allowed result = DISCOVERY_BARE_ALWAYS; + git_protected_config(discovery_bare_cb, &result); + return result; +} + +static const char *discovery_bare_allowed_to_string( + enum discovery_bare_allowed discovery_bare_allowed) +{ + switch (discovery_bare_allowed) { + case DISCOVERY_BARE_NEVER: + return "never"; + case DISCOVERY_BARE_ALWAYS: + return "always"; + default: + BUG("invalid discovery_bare_allowed %d", + discovery_bare_allowed); + } + return NULL; +} + enum discovery_result { GIT_DIR_NONE = 0, GIT_DIR_EXPLICIT, @@ -1151,7 +1195,8 @@ enum discovery_result { GIT_DIR_HIT_CEILING = -1, GIT_DIR_HIT_MOUNT_POINT = -2, GIT_DIR_INVALID_GITFILE = -3, - GIT_DIR_INVALID_OWNERSHIP = -4 + GIT_DIR_INVALID_OWNERSHIP = -4, + GIT_DIR_DISALLOWED_BARE = -5, }; /* @@ -1248,6 +1293,8 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir, } if (is_git_directory(dir->buf)) { + if (!get_discovery_bare()) + return GIT_DIR_DISALLOWED_BARE; if (!ensure_valid_ownership(dir->buf)) return GIT_DIR_INVALID_OWNERSHIP; strbuf_addstr(gitdir, "."); @@ -1394,6 +1441,14 @@ const char *setup_git_directory_gently(int *nongit_ok) } *nongit_ok = 1; break; + case GIT_DIR_DISALLOWED_BARE: + if (!nongit_ok) { + die(_("cannot use bare repository '%s' (discovery.bare is '%s')"), + dir.buf, + discovery_bare_allowed_to_string(get_discovery_bare())); + } + *nongit_ok = 1; + break; case GIT_DIR_NONE: /* * As a safeguard against setup_git_directory_gently_1 returning diff --git a/t/t0035-discovery-bare.sh b/t/t0035-discovery-bare.sh new file mode 100755 index 00000000000..0b345d361e6 --- /dev/null +++ b/t/t0035-discovery-bare.sh @@ -0,0 +1,68 @@ +#!/bin/sh + +test_description='verify discovery.bare checks' + +. ./test-lib.sh + +pwd="$(pwd)" + +expect_accepted () { + git "$@" rev-parse --git-dir +} + +expect_rejected () { + test_must_fail git "$@" rev-parse --git-dir 2>err && + grep "discovery.bare" err +} + +test_expect_success 'setup bare repo in worktree' ' + git init outer-repo && + git init --bare outer-repo/bare-repo +' + +test_expect_success 'discovery.bare unset' ' + ( + cd outer-repo/bare-repo && + expect_accepted + ) +' + +test_expect_success 'discovery.bare=always' ' + git config --global discovery.bare always && + ( + cd outer-repo/bare-repo && + expect_accepted + ) +' + +test_expect_success 'discovery.bare=never' ' + git config --global discovery.bare never && + ( + cd outer-repo/bare-repo && + expect_rejected + ) +' + +test_expect_success 'discovery.bare in the repository' ' + ( + cd outer-repo/bare-repo && + # Temporarily set discovery.bare=always, otherwise git + # config fails with "fatal: not in a git directory" + # (like safe.directory) + git config --global discovery.bare always && + git config discovery.bare always && + git config --global discovery.bare never && + expect_rejected + ) +' + +test_expect_success 'discovery.bare on the command line' ' + git config --global discovery.bare never && + ( + cd outer-repo/bare-repo && + expect_accepted -c discovery.bare=always && + expect_rejected -c discovery.bare= + ) +' + +test_done