From 516e2b76bdcf53e757309481fa0e663217ee8039 Mon Sep 17 00:00:00 2001 From: Brandon Williams Date: Wed, 27 Jun 2018 15:30:17 -0700 Subject: upload-pack: implement ref-in-want Currently, while performing packfile negotiation, clients are only allowed to specify their desired objects using object ids. This causes a vulnerability to failure when an object turns non-existent during negotiation, which may happen if, for example, the desired repository is provided by multiple Git servers in a load-balancing arrangement and there exists replication delay. In order to eliminate this vulnerability, implement the ref-in-want feature for the 'fetch' command in protocol version 2. This feature enables the 'fetch' command to support requests in the form of ref names through a new "want-ref " parameter. At the conclusion of negotiation, the server will send a list of all of the wanted references (as provided by "want-ref" lines) in addition to the generated packfile. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano --- upload-pack.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) (limited to 'upload-pack.c') diff --git a/upload-pack.c b/upload-pack.c index 87c6722ea5..6dd82e5607 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -64,6 +64,7 @@ static const char *pack_objects_hook; static int filter_capability_requested; static int allow_filter; +static int allow_ref_in_want; static struct list_objects_filter_options filter_options; static void reset_timeout(void) @@ -1075,6 +1076,8 @@ static int upload_pack_config(const char *var, const char *value, void *unused) return git_config_string(&pack_objects_hook, var, value); } else if (!strcmp("uploadpack.allowfilter", var)) { allow_filter = git_config_bool(var, value); + } else if (!strcmp("uploadpack.allowrefinwant", var)) { + allow_ref_in_want = git_config_bool(var, value); } return parse_hide_refs_config(var, value, "uploadpack"); } @@ -1114,6 +1117,7 @@ void upload_pack(struct upload_pack_options *options) struct upload_pack_data { struct object_array wants; + struct string_list wanted_refs; struct oid_array haves; struct object_array shallows; @@ -1135,12 +1139,14 @@ struct upload_pack_data { static void upload_pack_data_init(struct upload_pack_data *data) { struct object_array wants = OBJECT_ARRAY_INIT; + struct string_list wanted_refs = STRING_LIST_INIT_DUP; struct oid_array haves = OID_ARRAY_INIT; struct object_array shallows = OBJECT_ARRAY_INIT; struct string_list deepen_not = STRING_LIST_INIT_DUP; memset(data, 0, sizeof(*data)); data->wants = wants; + data->wanted_refs = wanted_refs; data->haves = haves; data->shallows = shallows; data->deepen_not = deepen_not; @@ -1149,6 +1155,7 @@ static void upload_pack_data_init(struct upload_pack_data *data) static void upload_pack_data_clear(struct upload_pack_data *data) { object_array_clear(&data->wants); + string_list_clear(&data->wanted_refs, 1); oid_array_clear(&data->haves); object_array_clear(&data->shallows); string_list_clear(&data->deepen_not, 0); @@ -1185,6 +1192,34 @@ static int parse_want(const char *line) return 0; } +static int parse_want_ref(const char *line, struct string_list *wanted_refs) +{ + const char *arg; + if (skip_prefix(line, "want-ref ", &arg)) { + struct object_id oid; + struct string_list_item *item; + struct object *o; + + if (read_ref(arg, &oid)) { + packet_write_fmt(1, "ERR unknown ref %s", arg); + die("unknown ref %s", arg); + } + + item = string_list_append(wanted_refs, arg); + item->util = oiddup(&oid); + + o = parse_object_or_die(&oid, arg); + if (!(o->flags & WANTED)) { + o->flags |= WANTED; + add_object_array(o, NULL, &want_obj); + } + + return 1; + } + + return 0; +} + static int parse_have(const char *line, struct oid_array *haves) { const char *arg; @@ -1210,6 +1245,8 @@ static void process_args(struct packet_reader *request, /* process want */ if (parse_want(arg)) continue; + if (allow_ref_in_want && parse_want_ref(arg, &data->wanted_refs)) + continue; /* process have line */ if (parse_have(arg, &data->haves)) continue; @@ -1352,6 +1389,24 @@ static int process_haves_and_send_acks(struct upload_pack_data *data) return ret; } +static void send_wanted_ref_info(struct upload_pack_data *data) +{ + const struct string_list_item *item; + + if (!data->wanted_refs.nr) + return; + + packet_write_fmt(1, "wanted-refs\n"); + + for_each_string_list_item(item, &data->wanted_refs) { + packet_write_fmt(1, "%s %s\n", + oid_to_hex(item->util), + item->string); + } + + packet_delim(1); +} + static void send_shallow_info(struct upload_pack_data *data) { /* No shallow info needs to be sent */ @@ -1418,6 +1473,7 @@ int upload_pack_v2(struct repository *r, struct argv_array *keys, state = FETCH_DONE; break; case FETCH_SEND_PACK: + send_wanted_ref_info(&data); send_shallow_info(&data); packet_write_fmt(1, "packfile\n"); @@ -1438,12 +1494,22 @@ int upload_pack_advertise(struct repository *r, { if (value) { int allow_filter_value; + int allow_ref_in_want; + strbuf_addstr(value, "shallow"); + if (!repo_config_get_bool(the_repository, "uploadpack.allowfilter", &allow_filter_value) && allow_filter_value) strbuf_addstr(value, " filter"); + + if (!repo_config_get_bool(the_repository, + "uploadpack.allowrefinwant", + &allow_ref_in_want) && + allow_ref_in_want) + strbuf_addstr(value, " ref-in-want"); } + return 1; } -- cgit v1.2.3