From f659612c9d78666a317a614a68a2b93dec94db70 Mon Sep 17 00:00:00 2001 From: Justin Tobler Date: Thu, 3 Apr 2025 11:09:55 -0500 Subject: [PATCH 1/2] t5410: test receive-pack connectivity check As part of git-recieve-pack(1), the connectivity of objects is checked. Add a test validating that git-receive-pack(1) fails due to an incoming packfile that would leave the repository with missing objects. Instead of creating a new test file, "t5410" is generalized for receive-pack testing. Signed-off-by: Justin Tobler --- t/meson.build | 2 +- ...ck-alternates.sh => t5410-receive-pack.sh} | 23 ++++++++++++++++++- 2 files changed, 23 insertions(+), 2 deletions(-) rename t/{t5410-receive-pack-alternates.sh => t5410-receive-pack.sh} (57%) diff --git a/t/meson.build b/t/meson.build index 43c9750b88e..6b7c0b167bf 100644 --- a/t/meson.build +++ b/t/meson.build @@ -628,7 +628,7 @@ integration_tests = [ 't5407-post-rewrite-hook.sh', 't5408-send-pack-stdin.sh', 't5409-colorize-remote-messages.sh', - 't5410-receive-pack-alternates.sh', + 't5410-receive-pack.sh', 't5411-proc-receive-hook.sh', 't5500-fetch-pack.sh', 't5501-fetch-push-alternates.sh', diff --git a/t/t5410-receive-pack-alternates.sh b/t/t5410-receive-pack.sh similarity index 57% rename from t/t5410-receive-pack-alternates.sh rename to t/t5410-receive-pack.sh index 4e82fd102e3..9afea54a267 100755 --- a/t/t5410-receive-pack-alternates.sh +++ b/t/t5410-receive-pack.sh @@ -1,6 +1,6 @@ #!/bin/sh -test_description='git receive-pack with alternate ref filtering' +test_description='git receive-pack' GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME @@ -41,4 +41,25 @@ test_expect_success 'with core.alternateRefsPrefixes' ' test_cmp expect actual.haves ' +test_expect_success 'receive-pack missing objects fails connectivity check' ' + test_when_finished rm -rf repo remote.git setup.git && + + git init repo && + git -C repo commit --allow-empty -m 1 && + git clone --bare repo setup.git && + git -C repo commit --allow-empty -m 2 && + + # Capture git-send-pack(1) output sent to git-receive-pack(1). + git -C repo send-pack ../setup.git --all \ + --receive-pack="tee ${SQ}$(pwd)/out${SQ} | git-receive-pack" && + + # Replay captured git-send-pack(1) output on new empty repository. + git init --bare remote.git && + git receive-pack remote.git actual 2>err && + + test_grep "missing necessary objects" actual && + test_grep "fatal: Failed to traverse parents" err && + test_must_fail git -C remote.git cat-file -e $(git -C repo rev-parse HEAD) +' + test_done -- GitLab From f6dbb0277877bb077f6d6cde2f55f18c6567c3be Mon Sep 17 00:00:00 2001 From: Justin Tobler Date: Wed, 23 Apr 2025 17:11:09 -0500 Subject: [PATCH 2/2] builtin/receive-pack: add option to skip connectivity check During git-receive-pack(1), connectivity of the object graph is validated to ensure that the received packfile does not leave the repository in a broken state. This is done via git-rev-list(1) and walking the objects, which can be expensive for large repositories. Generally, this check is critical to avoid an incomplete received packfile from corrupting a repository. Server operators may have additional knowledge though around exactly how Git is being used on the server-side which can be used to facilitate more efficient connectivity computation of incoming objects. For example, if it can be ensured that all objects in a repository are connected and do not depend on any missing objects, the connectivity of newly written objects can be checked by walking the object graph containing only the new objects from the updated tips and identifying the missing objects which represent the boundary between the new objects and the repository. These boundary objects can be checked in the canonical repository to ensure the new objects connect as expected and thus avoid walking the rest of the object graph. Git itself cannot make the guarantees required for such an optimization as it is possible for a repository to contain an unreachable object that references a missing object without the repository being considered corrupt. Introduce the --skip-connectivity-check option for git-receive-pack(1) which bypasses this connectivity check to give more control to the server-side. Note that without proper server-side validation of newly received objects handled outside of Git, usage of this option risks corrupting a repository. Signed-off-by: Justin Tobler --- Documentation/git-receive-pack.adoc | 12 +++++++++ builtin/receive-pack.c | 40 ++++++++++++++++------------- t/t5410-receive-pack.sh | 22 ++++++++++++++++ 3 files changed, 56 insertions(+), 18 deletions(-) diff --git a/Documentation/git-receive-pack.adoc b/Documentation/git-receive-pack.adoc index 20aca92073d..0956086d611 100644 --- a/Documentation/git-receive-pack.adoc +++ b/Documentation/git-receive-pack.adoc @@ -46,6 +46,18 @@ OPTIONS `$GIT_URL/info/refs?service=git-receive-pack` requests. See `--http-backend-info-refs` in linkgit:git-upload-pack[1]. +--skip-connectivity-check:: + Bypasses the connectivity checks that validate the existence of all + objects in the transitive closure of reachable objects. This option is + intended for server operators that want to implement their own object + connectivity validation outside of Git. This is useful in such cases + where the server-side knows additional information about how Git is + being used and thus can rely on certain guarantees to more efficiently + compute object connectivity that Git itself cannot make. Usage of this + option without a reliable external mechanism to ensure full reachable + object connectivity risks corrupting the repository and should not be + used in the general case. + PRE-RECEIVE HOOK ---------------- Before any ref is updated, if $GIT_DIR/hooks/pre-receive file exists diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c index be314879e82..66674bc408f 100644 --- a/builtin/receive-pack.c +++ b/builtin/receive-pack.c @@ -81,6 +81,7 @@ static int prefer_ofs_delta = 1; static int auto_update_server_info; static int auto_gc = 1; static int reject_thin; +static int skip_connectivity_check; static int stateless_rpc; static const char *service_dir; static const char *head_name; @@ -1936,27 +1937,29 @@ static void execute_commands(struct command *commands, return; } - if (use_sideband) { - memset(&muxer, 0, sizeof(muxer)); - muxer.proc = copy_to_sideband; - muxer.in = -1; - if (!start_async(&muxer)) - err_fd = muxer.in; - /* ...else, continue without relaying sideband */ - } + if (!skip_connectivity_check) { + if (use_sideband) { + memset(&muxer, 0, sizeof(muxer)); + muxer.proc = copy_to_sideband; + muxer.in = -1; + if (!start_async(&muxer)) + err_fd = muxer.in; + /* ...else, continue without relaying sideband */ + } - data.cmds = commands; - data.si = si; - opt.err_fd = err_fd; - opt.progress = err_fd && !quiet; - opt.env = tmp_objdir_env(tmp_objdir); - opt.exclude_hidden_refs_section = "receive"; + data.cmds = commands; + data.si = si; + opt.err_fd = err_fd; + opt.progress = err_fd && !quiet; + opt.env = tmp_objdir_env(tmp_objdir); + opt.exclude_hidden_refs_section = "receive"; - if (check_connected(iterate_receive_command_list, &data, &opt)) - set_connectivity_errors(commands, si); + if (check_connected(iterate_receive_command_list, &data, &opt)) + set_connectivity_errors(commands, si); - if (use_sideband) - finish_async(&muxer); + if (use_sideband) + finish_async(&muxer); + } reject_updates_to_hidden(commands); @@ -2517,6 +2520,7 @@ int cmd_receive_pack(int argc, struct option options[] = { OPT__QUIET(&quiet, N_("quiet")), + OPT_HIDDEN_BOOL(0, "skip-connectivity-check", &skip_connectivity_check, NULL), OPT_HIDDEN_BOOL(0, "stateless-rpc", &stateless_rpc, NULL), OPT_HIDDEN_BOOL(0, "http-backend-info-refs", &advertise_refs, NULL), OPT_ALIAS(0, "advertise-refs", "http-backend-info-refs"), diff --git a/t/t5410-receive-pack.sh b/t/t5410-receive-pack.sh index 9afea54a267..f76a22943ef 100755 --- a/t/t5410-receive-pack.sh +++ b/t/t5410-receive-pack.sh @@ -62,4 +62,26 @@ test_expect_success 'receive-pack missing objects fails connectivity check' ' test_must_fail git -C remote.git cat-file -e $(git -C repo rev-parse HEAD) ' +test_expect_success 'receive-pack missing objects bypasses connectivity check' ' + test_when_finished rm -rf repo remote.git setup.git && + + git init repo && + git -C repo commit --allow-empty -m 1 && + git clone --bare repo setup.git && + git -C repo commit --allow-empty -m 2 && + + # Capture git-send-pack(1) output sent to git-receive-pack(1). + git -C repo send-pack ../setup.git --all \ + --receive-pack="tee ${SQ}$(pwd)/out${SQ} | git-receive-pack" && + + # Replay captured git-send-pack(1) output on new empty repository. + git init --bare remote.git && + git receive-pack --skip-connectivity-check remote.git actual 2>err && + + test_grep ! "missing necessary objects" actual && + test_must_be_empty err && + git -C remote.git cat-file -e $(git -C repo rev-parse HEAD) && + test_must_fail git -C remote.git rev-list $(git -C repo rev-parse HEAD) +' + test_done -- GitLab