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b0df0c16ea
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 before the transaction is complete, remote-curl will blindly forward the packets before waiting on more input from fetch-pack. Meanwhile, fetch-pack will read the transaction and continue reading, expecting more input to continue the transaction. This results in a deadlock between the two processes. This can be seen in the following command which does not terminate: $ git -c protocol.version=2 clone https://github.com/git/git.git --shallow-since=20151012 Cloning into 'git'... whereas the v1 version does terminate as expected: $ git -c protocol.version=1 clone https://github.com/git/git.git --shallow-since=20151012 Cloning into 'git'... fatal: the remote end hung up unexpectedly Instead of blindly forwarding packets, make remote-curl insert a response end packet after proxying the responses from the remote server when using stateless_connect(). On the RPC client side, ensure that each response ends as described. A separate control packet is chosen because we need to be able to differentiate between what the remote server sends and remote-curl's control packets. By ensuring in the remote-curl code that a server cannot send response end packets, we prevent a malicious server from being able to perform a denial of service attack in which they spoof a response end packet and cause the described deadlock to happen. Reported-by: Force Charlie <charlieio@outlook.com> Helped-by: Jeff King <peff@peff.net> Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
30 lines
1012 B
C
30 lines
1012 B
C
#ifndef CONNECT_H
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#define CONNECT_H
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#include "protocol.h"
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#define CONNECT_VERBOSE (1u << 0)
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#define CONNECT_DIAG_URL (1u << 1)
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#define CONNECT_IPV4 (1u << 2)
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#define CONNECT_IPV6 (1u << 3)
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struct child_process *git_connect(int fd[2], const char *url, const char *prog, int flags);
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int finish_connect(struct child_process *conn);
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int git_connection_is_socket(struct child_process *conn);
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int server_supports(const char *feature);
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int parse_feature_request(const char *features, const char *feature);
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const char *server_feature_value(const char *feature, int *len_ret);
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int url_is_local_not_ssh(const char *url);
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struct packet_reader;
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enum protocol_version discover_version(struct packet_reader *reader);
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int server_supports_v2(const char *c, int die_on_error);
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int server_supports_feature(const char *c, const char *feature,
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int die_on_error);
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void check_stateless_delimiter(int stateless_rpc,
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struct packet_reader *reader,
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const char *error);
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#endif
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