mirror of
https://github.com/git-for-windows/git.git
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090fd4fe24
The current parsing scheme for upload-archive is to pack arguments into a fixed-size buffer, separated by NULs, and put a pointer to each argument in the buffer into a fixed-size argv array. This works fine, and the limits are high enough that nobody reasonable is going to hit them, but it makes the code hard to follow. Instead, let's just stuff the arguments into an argv_array, which is much simpler. That lifts the "all arguments must fit inside 4K together" limit. We could also trivially lift the MAX_ARGS limitation (in fact, we have to keep extra code to enforce it). But that would mean a client could force us to allocate an arbitrary amount of memory simply by sending us "argument" lines. By limiting the MAX_ARGS, we limit an attacker to about 4 megabytes (64 times a maximum 64K packet buffer). That may sound like a lot compared to the 4K limit, but it's not a big deal compared to what git-archive will actually allocate while working (e.g., to load blobs into memory). The important thing is that it is bounded. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/*
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* Copyright (c) 2006 Franck Bui-Huu
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*/
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#include "cache.h"
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#include "builtin.h"
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#include "archive.h"
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#include "pkt-line.h"
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#include "sideband.h"
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#include "run-command.h"
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#include "argv-array.h"
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static const char upload_archive_usage[] =
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"git upload-archive <repo>";
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static const char deadchild[] =
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"git upload-archive: archiver died with error";
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#define MAX_ARGS (64)
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int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix)
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{
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struct argv_array sent_argv = ARGV_ARRAY_INIT;
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const char *arg_cmd = "argument ";
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char buf[4096];
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int len;
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if (argc != 2)
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usage(upload_archive_usage);
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if (!enter_repo(argv[1], 0))
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die("'%s' does not appear to be a git repository", argv[1]);
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/* put received options in sent_argv[] */
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argv_array_push(&sent_argv, "git-upload-archive");
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for (;;) {
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/* This will die if not enough free space in buf */
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len = packet_read_line(0, buf, sizeof(buf));
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if (len == 0)
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break; /* got a flush */
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if (sent_argv.argc > MAX_ARGS)
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die("Too many options (>%d)", MAX_ARGS - 1);
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if (buf[len-1] == '\n') {
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buf[--len] = 0;
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}
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if (prefixcmp(buf, arg_cmd))
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die("'argument' token or flush expected");
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argv_array_push(&sent_argv, buf + strlen(arg_cmd));
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}
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/* parse all options sent by the client */
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return write_archive(sent_argv.argc, sent_argv.argv, prefix, 0, NULL, 1);
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}
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__attribute__((format (printf, 1, 2)))
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static void error_clnt(const char *fmt, ...)
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{
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char buf[1024];
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va_list params;
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int len;
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va_start(params, fmt);
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len = vsprintf(buf, fmt, params);
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va_end(params);
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send_sideband(1, 3, buf, len, LARGE_PACKET_MAX);
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die("sent error to the client: %s", buf);
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}
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static ssize_t process_input(int child_fd, int band)
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{
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char buf[16384];
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ssize_t sz = read(child_fd, buf, sizeof(buf));
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if (sz < 0) {
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if (errno != EAGAIN && errno != EINTR)
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error_clnt("read error: %s\n", strerror(errno));
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return sz;
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}
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send_sideband(1, band, buf, sz, LARGE_PACKET_MAX);
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return sz;
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}
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int cmd_upload_archive(int argc, const char **argv, const char *prefix)
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{
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struct child_process writer = { argv };
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/*
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* Set up sideband subprocess.
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*
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* We (parent) monitor and read from child, sending its fd#1 and fd#2
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* multiplexed out to our fd#1. If the child dies, we tell the other
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* end over channel #3.
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*/
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argv[0] = "upload-archive--writer";
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writer.out = writer.err = -1;
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writer.git_cmd = 1;
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if (start_command(&writer)) {
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int err = errno;
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packet_write(1, "NACK unable to spawn subprocess\n");
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die("upload-archive: %s", strerror(err));
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}
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packet_write(1, "ACK\n");
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packet_flush(1);
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while (1) {
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struct pollfd pfd[2];
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pfd[0].fd = writer.out;
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pfd[0].events = POLLIN;
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pfd[1].fd = writer.err;
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pfd[1].events = POLLIN;
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if (poll(pfd, 2, -1) < 0) {
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if (errno != EINTR) {
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error("poll failed resuming: %s",
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strerror(errno));
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sleep(1);
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}
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continue;
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}
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if (pfd[1].revents & POLLIN)
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/* Status stream ready */
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if (process_input(pfd[1].fd, 2))
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continue;
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if (pfd[0].revents & POLLIN)
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/* Data stream ready */
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if (process_input(pfd[0].fd, 1))
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continue;
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if (finish_command(&writer))
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error_clnt("%s", deadchild);
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packet_flush(1);
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break;
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}
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return 0;
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}
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