From 74b082ad34fe2c727c676dac5c33d5e1e5f5ca56 Mon Sep 17 00:00:00 2001 From: Denton Liu Date: Tue, 19 May 2020 06:53:58 -0400 Subject: [PATCH] remote-curl: error on incomplete packet Currently, remote-curl acts as a proxy and blindly forwards packets between an HTTP server and fetch-pack. In the case of a stateless RPC connection where the connection is terminated with a partially written packet, remote-curl will blindly send the partially written packet before waiting on more input from fetch-pack. Meanwhile, fetch-pack will read the partial packet and continue reading, expecting more input. This results in a deadlock between the two processes. For a stateless connection, inspect packets before sending them and error out if a packet line packet is incomplete. Helped-by: Jeff King Signed-off-by: Denton Liu Signed-off-by: Junio C Hamano --- remote-curl.c | 59 ++++++++++++++++++- t/lib-httpd.sh | 2 + t/lib-httpd/apache.conf | 8 +++ .../incomplete-body-upload-pack-v2-http.sh | 3 + .../incomplete-length-upload-pack-v2-http.sh | 3 + t/t5702-protocol-v2.sh | 34 +++++++++++ 6 files changed, 106 insertions(+), 3 deletions(-) create mode 100644 t/lib-httpd/incomplete-body-upload-pack-v2-http.sh create mode 100644 t/lib-httpd/incomplete-length-upload-pack-v2-http.sh diff --git a/remote-curl.c b/remote-curl.c index da3e07184aed3c..e020140092dc56 100644 --- a/remote-curl.c +++ b/remote-curl.c @@ -679,9 +679,53 @@ static curlioerr rpc_ioctl(CURL *handle, int cmd, void *clientp) } #endif +struct check_pktline_state { + char len_buf[4]; + int len_filled; + int remaining; +}; + +static void check_pktline(struct check_pktline_state *state, const char *ptr, size_t size) +{ + while (size) { + if (!state->remaining) { + int digits_remaining = 4 - state->len_filled; + if (digits_remaining > size) + digits_remaining = size; + memcpy(&state->len_buf[state->len_filled], ptr, digits_remaining); + state->len_filled += digits_remaining; + ptr += digits_remaining; + size -= digits_remaining; + + if (state->len_filled == 4) { + state->remaining = packet_length(state->len_buf); + if (state->remaining < 0) { + die(_("remote-curl: bad line length character: %.4s"), state->len_buf); + } else if (state->remaining < 4) { + state->remaining = 0; + } else { + state->remaining -= 4; + } + state->len_filled = 0; + } + } + + if (state->remaining) { + int remaining = state->remaining; + if (remaining > size) + remaining = size; + ptr += remaining; + size -= remaining; + state->remaining -= remaining; + } + } +} + struct rpc_in_data { struct rpc_state *rpc; struct active_request_slot *slot; + int check_pktline; + struct check_pktline_state pktline_state; }; /* @@ -702,6 +746,8 @@ static size_t rpc_in(char *ptr, size_t eltsize, return size; if (size) data->rpc->any_written = 1; + if (data->check_pktline) + check_pktline(&data->pktline_state, ptr, size); write_or_die(data->rpc->in, ptr, size); return size; } @@ -778,7 +824,7 @@ static curl_off_t xcurl_off_t(size_t len) * If flush_received is true, do not attempt to read any more; just use what's * in rpc->buf. */ -static int post_rpc(struct rpc_state *rpc, int flush_received) +static int post_rpc(struct rpc_state *rpc, int stateless_connect, int flush_received) { struct active_request_slot *slot; struct curl_slist *headers = http_copy_default_headers(); @@ -920,6 +966,8 @@ static int post_rpc(struct rpc_state *rpc, int flush_received) curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, rpc_in); rpc_in_data.rpc = rpc; rpc_in_data.slot = slot; + rpc_in_data.check_pktline = stateless_connect; + memset(&rpc_in_data.pktline_state, 0, sizeof(rpc_in_data.pktline_state)); curl_easy_setopt(slot->curl, CURLOPT_FILE, &rpc_in_data); curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 0); @@ -936,6 +984,11 @@ static int post_rpc(struct rpc_state *rpc, int flush_received) if (!rpc->any_written) err = -1; + if (rpc_in_data.pktline_state.len_filled) + err = error(_("%d bytes of length header were received"), rpc_in_data.pktline_state.len_filled); + if (rpc_in_data.pktline_state.remaining) + err = error(_("%d bytes of body are still expected"), rpc_in_data.pktline_state.remaining); + curl_slist_free_all(headers); free(gzip_body); return err; @@ -985,7 +1038,7 @@ static int rpc_service(struct rpc_state *rpc, struct discovery *heads, break; rpc->pos = 0; rpc->len = n; - err |= post_rpc(rpc, 0); + err |= post_rpc(rpc, 0, 0); } close(client.in); @@ -1342,7 +1395,7 @@ static int stateless_connect(const char *service_name) BUG("The entire rpc->buf should be larger than LARGE_PACKET_MAX"); if (status == PACKET_READ_EOF) break; - if (post_rpc(&rpc, status == PACKET_READ_FLUSH)) + if (post_rpc(&rpc, 1, status == PACKET_READ_FLUSH)) /* We would have an err here */ break; /* Reset the buffer for next request */ diff --git a/t/lib-httpd.sh b/t/lib-httpd.sh index 1449ee95e9eaa0..d2edfa4c503af0 100644 --- a/t/lib-httpd.sh +++ b/t/lib-httpd.sh @@ -129,6 +129,8 @@ install_script () { prepare_httpd() { mkdir -p "$HTTPD_DOCUMENT_ROOT_PATH" cp "$TEST_PATH"/passwd "$HTTPD_ROOT_PATH" + install_script incomplete-length-upload-pack-v2-http.sh + install_script incomplete-body-upload-pack-v2-http.sh install_script broken-smart-http.sh install_script error-smart-http.sh install_script error.sh diff --git a/t/lib-httpd/apache.conf b/t/lib-httpd/apache.conf index 994e5290d63b0f..afa91e38b0e213 100644 --- a/t/lib-httpd/apache.conf +++ b/t/lib-httpd/apache.conf @@ -117,6 +117,8 @@ Alias /auth/dumb/ www/auth/dumb/ SetEnv GIT_EXEC_PATH ${GIT_EXEC_PATH} SetEnv GIT_HTTP_EXPORT_ALL +ScriptAlias /smart/incomplete_length/git-upload-pack incomplete-length-upload-pack-v2-http.sh/ +ScriptAlias /smart/incomplete_body/git-upload-pack incomplete-body-upload-pack-v2-http.sh/ ScriptAliasMatch /error_git_upload_pack/(.*)/git-upload-pack error.sh/ ScriptAliasMatch /smart_*[^/]*/(.*) ${GIT_EXEC_PATH}/git-http-backend/$1 ScriptAlias /broken_smart/ broken-smart-http.sh/ @@ -126,6 +128,12 @@ ScriptAliasMatch /one_time_perl/(.*) apply-one-time-perl.sh/$1 Options FollowSymlinks + + Options ExecCGI + + + Options ExecCGI + Options ExecCGI diff --git a/t/lib-httpd/incomplete-body-upload-pack-v2-http.sh b/t/lib-httpd/incomplete-body-upload-pack-v2-http.sh new file mode 100644 index 00000000000000..90e73ef8d559a5 --- /dev/null +++ b/t/lib-httpd/incomplete-body-upload-pack-v2-http.sh @@ -0,0 +1,3 @@ +printf "Content-Type: text/%s\n" "application/x-git-upload-pack-result" +echo +printf "%s%s" "0079" "45" diff --git a/t/lib-httpd/incomplete-length-upload-pack-v2-http.sh b/t/lib-httpd/incomplete-length-upload-pack-v2-http.sh new file mode 100644 index 00000000000000..dce552e3482398 --- /dev/null +++ b/t/lib-httpd/incomplete-length-upload-pack-v2-http.sh @@ -0,0 +1,3 @@ +printf "Content-Type: text/%s\n" "application/x-git-upload-pack-result" +echo +printf "%s" "00" diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh index 5039e66dc47c0e..4eb81ba2d49abe 100755 --- a/t/t5702-protocol-v2.sh +++ b/t/t5702-protocol-v2.sh @@ -586,6 +586,40 @@ test_expect_success 'clone with http:// using protocol v2' ' ! grep "Send header: Transfer-Encoding: chunked" log ' +test_expect_success 'clone repository with http:// using protocol v2 with incomplete pktline length' ' + test_when_finished "rm -f log" && + + git init "$HTTPD_DOCUMENT_ROOT_PATH/incomplete_length" && + test_commit -C "$HTTPD_DOCUMENT_ROOT_PATH/incomplete_length" file && + + test_must_fail env GIT_TRACE_PACKET="$(pwd)/log" GIT_TRACE_CURL="$(pwd)/log" git -c protocol.version=2 \ + clone "$HTTPD_URL/smart/incomplete_length" incomplete_length_child 2>err && + + # Client requested to use protocol v2 + grep "Git-Protocol: version=2" log && + # Server responded using protocol v2 + grep "git< version 2" log && + # Client reported appropriate failure + test_i18ngrep "bytes of length header were received" err +' + +test_expect_success 'clone repository with http:// using protocol v2 with incomplete pktline body' ' + test_when_finished "rm -f log" && + + git init "$HTTPD_DOCUMENT_ROOT_PATH/incomplete_body" && + test_commit -C "$HTTPD_DOCUMENT_ROOT_PATH/incomplete_body" file && + + test_must_fail env GIT_TRACE_PACKET="$(pwd)/log" GIT_TRACE_CURL="$(pwd)/log" git -c protocol.version=2 \ + clone "$HTTPD_URL/smart/incomplete_body" incomplete_body_child 2>err && + + # Client requested to use protocol v2 + grep "Git-Protocol: version=2" log && + # Server responded using protocol v2 + grep "git< version 2" log && + # Client reported appropriate failure + test_i18ngrep "bytes of body are still expected" err +' + test_expect_success 'clone big repository with http:// using protocol v2' ' test_when_finished "rm -f log" &&