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synced 2024-08-24 18:26:02 +00:00
![Junio C Hamano](/assets/img/avatar_default.png)
In order to prevent a valid push certificate for pushing into an repository from getting replayed in a different push operation, send a nonce string from the receive-pack process and have the signer include it in the push certificate. The receiving end uses an HMAC hash of the path to the repository it serves and the current time stamp, hashed with a secret seed (the secret seed does not have to be per-repository but can be defined in /etc/gitconfig) to generate the nonce, in order to ensure that a random third party cannot forge a nonce that looks like it originated from it. The original nonce is exported as GIT_PUSH_CERT_NONCE for the hooks to examine and match against the value on the "nonce" header in the certificate to notice a replay, but returned "nonce" header in the push certificate is examined by receive-pack and the result is exported as GIT_PUSH_CERT_NONCE_STATUS, whose value would be "OK" if the nonce recorded in the certificate matches what we expect, so that the hooks can more easily check. Signed-off-by: Junio C Hamano <gitster@pobox.com>
476 lines
11 KiB
C
476 lines
11 KiB
C
#include "builtin.h"
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#include "commit.h"
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#include "refs.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 "remote.h"
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#include "connect.h"
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#include "send-pack.h"
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#include "quote.h"
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#include "transport.h"
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#include "version.h"
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#include "sha1-array.h"
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#include "gpg-interface.h"
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static int feed_object(const unsigned char *sha1, int fd, int negative)
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{
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char buf[42];
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if (negative && !has_sha1_file(sha1))
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return 1;
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memcpy(buf + negative, sha1_to_hex(sha1), 40);
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if (negative)
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buf[0] = '^';
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buf[40 + negative] = '\n';
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return write_or_whine(fd, buf, 41 + negative, "send-pack: send refs");
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}
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/*
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* Make a pack stream and spit it out into file descriptor fd
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*/
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static int pack_objects(int fd, struct ref *refs, struct sha1_array *extra, struct send_pack_args *args)
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{
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/*
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* The child becomes pack-objects --revs; we feed
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* the revision parameters to it via its stdin and
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* let its stdout go back to the other end.
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*/
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const char *argv[] = {
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"pack-objects",
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"--all-progress-implied",
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"--revs",
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"--stdout",
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NULL,
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NULL,
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NULL,
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NULL,
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NULL,
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};
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struct child_process po;
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int i;
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i = 4;
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if (args->use_thin_pack)
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argv[i++] = "--thin";
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if (args->use_ofs_delta)
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argv[i++] = "--delta-base-offset";
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if (args->quiet || !args->progress)
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argv[i++] = "-q";
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if (args->progress)
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argv[i++] = "--progress";
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memset(&po, 0, sizeof(po));
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po.argv = argv;
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po.in = -1;
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po.out = args->stateless_rpc ? -1 : fd;
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po.git_cmd = 1;
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if (start_command(&po))
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die_errno("git pack-objects failed");
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/*
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* We feed the pack-objects we just spawned with revision
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* parameters by writing to the pipe.
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*/
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for (i = 0; i < extra->nr; i++)
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if (!feed_object(extra->sha1[i], po.in, 1))
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break;
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while (refs) {
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if (!is_null_sha1(refs->old_sha1) &&
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!feed_object(refs->old_sha1, po.in, 1))
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break;
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if (!is_null_sha1(refs->new_sha1) &&
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!feed_object(refs->new_sha1, po.in, 0))
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break;
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refs = refs->next;
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}
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close(po.in);
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if (args->stateless_rpc) {
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char *buf = xmalloc(LARGE_PACKET_MAX);
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while (1) {
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ssize_t n = xread(po.out, buf, LARGE_PACKET_MAX);
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if (n <= 0)
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break;
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send_sideband(fd, -1, buf, n, LARGE_PACKET_MAX);
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}
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free(buf);
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close(po.out);
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po.out = -1;
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}
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if (finish_command(&po))
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return -1;
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return 0;
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}
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static int receive_status(int in, struct ref *refs)
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{
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struct ref *hint;
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int ret = 0;
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char *line = packet_read_line(in, NULL);
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if (!starts_with(line, "unpack "))
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return error("did not receive remote status");
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if (strcmp(line, "unpack ok")) {
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error("unpack failed: %s", line + 7);
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ret = -1;
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}
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hint = NULL;
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while (1) {
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char *refname;
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char *msg;
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line = packet_read_line(in, NULL);
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if (!line)
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break;
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if (!starts_with(line, "ok ") && !starts_with(line, "ng ")) {
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error("invalid ref status from remote: %s", line);
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ret = -1;
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break;
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}
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refname = line + 3;
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msg = strchr(refname, ' ');
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if (msg)
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*msg++ = '\0';
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/* first try searching at our hint, falling back to all refs */
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if (hint)
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hint = find_ref_by_name(hint, refname);
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if (!hint)
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hint = find_ref_by_name(refs, refname);
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if (!hint) {
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warning("remote reported status on unknown ref: %s",
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refname);
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continue;
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}
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if (hint->status != REF_STATUS_EXPECTING_REPORT) {
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warning("remote reported status on unexpected ref: %s",
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refname);
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continue;
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}
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if (line[0] == 'o' && line[1] == 'k')
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hint->status = REF_STATUS_OK;
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else {
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hint->status = REF_STATUS_REMOTE_REJECT;
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ret = -1;
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}
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if (msg)
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hint->remote_status = xstrdup(msg);
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/* start our next search from the next ref */
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hint = hint->next;
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}
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return ret;
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}
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static int sideband_demux(int in, int out, void *data)
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{
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int *fd = data, ret;
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#ifdef NO_PTHREADS
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close(fd[1]);
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#endif
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ret = recv_sideband("send-pack", fd[0], out);
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close(out);
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return ret;
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}
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static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
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{
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struct strbuf *sb = cb;
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if (graft->nr_parent == -1)
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packet_buf_write(sb, "shallow %s\n", sha1_to_hex(graft->sha1));
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return 0;
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}
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static void advertise_shallow_grafts_buf(struct strbuf *sb)
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{
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if (!is_repository_shallow())
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return;
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for_each_commit_graft(advertise_shallow_grafts_cb, sb);
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}
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static int ref_update_to_be_sent(const struct ref *ref, const struct send_pack_args *args)
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{
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if (!ref->peer_ref && !args->send_mirror)
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return 0;
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/* Check for statuses set by set_ref_status_for_push() */
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switch (ref->status) {
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case REF_STATUS_REJECT_NONFASTFORWARD:
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case REF_STATUS_REJECT_ALREADY_EXISTS:
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case REF_STATUS_REJECT_FETCH_FIRST:
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case REF_STATUS_REJECT_NEEDS_FORCE:
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case REF_STATUS_REJECT_STALE:
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case REF_STATUS_REJECT_NODELETE:
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case REF_STATUS_UPTODATE:
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return 0;
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default:
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return 1;
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}
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}
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/*
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* the beginning of the next line, or the end of buffer.
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*
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* NEEDSWORK: perhaps move this to git-compat-util.h or somewhere and
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* convert many similar uses found by "git grep -A4 memchr".
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*/
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static const char *next_line(const char *line, size_t len)
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{
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const char *nl = memchr(line, '\n', len);
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if (!nl)
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return line + len; /* incomplete line */
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return nl + 1;
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}
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static int generate_push_cert(struct strbuf *req_buf,
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const struct ref *remote_refs,
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struct send_pack_args *args,
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const char *cap_string,
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const char *push_cert_nonce)
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{
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const struct ref *ref;
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char stamp[60];
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char *signing_key = xstrdup(get_signing_key());
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const char *cp, *np;
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struct strbuf cert = STRBUF_INIT;
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int update_seen = 0;
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datestamp(stamp, sizeof(stamp));
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strbuf_addf(&cert, "certificate version 0.1\n");
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strbuf_addf(&cert, "pusher %s %s\n", signing_key, stamp);
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if (args->url && *args->url) {
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char *anon_url = transport_anonymize_url(args->url);
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strbuf_addf(&cert, "pushee %s\n", anon_url);
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free(anon_url);
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}
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if (push_cert_nonce[0])
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strbuf_addf(&cert, "nonce %s\n", push_cert_nonce);
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strbuf_addstr(&cert, "\n");
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for (ref = remote_refs; ref; ref = ref->next) {
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if (!ref_update_to_be_sent(ref, args))
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continue;
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update_seen = 1;
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strbuf_addf(&cert, "%s %s %s\n",
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sha1_to_hex(ref->old_sha1),
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sha1_to_hex(ref->new_sha1),
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ref->name);
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}
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if (!update_seen)
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goto free_return;
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if (sign_buffer(&cert, &cert, signing_key))
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die(_("failed to sign the push certificate"));
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packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string);
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for (cp = cert.buf; cp < cert.buf + cert.len; cp = np) {
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np = next_line(cp, cert.buf + cert.len - cp);
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packet_buf_write(req_buf,
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"%.*s", (int)(np - cp), cp);
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}
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packet_buf_write(req_buf, "push-cert-end\n");
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free_return:
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free(signing_key);
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strbuf_release(&cert);
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return update_seen;
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}
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int send_pack(struct send_pack_args *args,
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int fd[], struct child_process *conn,
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struct ref *remote_refs,
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struct sha1_array *extra_have)
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{
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int in = fd[0];
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int out = fd[1];
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struct strbuf req_buf = STRBUF_INIT;
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struct strbuf cap_buf = STRBUF_INIT;
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struct ref *ref;
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int need_pack_data = 0;
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int allow_deleting_refs = 0;
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int status_report = 0;
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int use_sideband = 0;
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int quiet_supported = 0;
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int agent_supported = 0;
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unsigned cmds_sent = 0;
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int ret;
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struct async demux;
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const char *push_cert_nonce = NULL;
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/* Does the other end support the reporting? */
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if (server_supports("report-status"))
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status_report = 1;
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if (server_supports("delete-refs"))
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allow_deleting_refs = 1;
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if (server_supports("ofs-delta"))
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args->use_ofs_delta = 1;
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if (server_supports("side-band-64k"))
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use_sideband = 1;
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if (server_supports("quiet"))
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quiet_supported = 1;
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if (server_supports("agent"))
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agent_supported = 1;
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if (server_supports("no-thin"))
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args->use_thin_pack = 0;
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if (args->push_cert) {
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int len;
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push_cert_nonce = server_feature_value("push-cert", &len);
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if (!push_cert_nonce)
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die(_("the receiving end does not support --signed push"));
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push_cert_nonce = xmemdupz(push_cert_nonce, len);
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}
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if (!remote_refs) {
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fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
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"Perhaps you should specify a branch such as 'master'.\n");
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return 0;
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}
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if (status_report)
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strbuf_addstr(&cap_buf, " report-status");
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if (use_sideband)
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strbuf_addstr(&cap_buf, " side-band-64k");
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if (quiet_supported && (args->quiet || !args->progress))
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strbuf_addstr(&cap_buf, " quiet");
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if (agent_supported)
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strbuf_addf(&cap_buf, " agent=%s", git_user_agent_sanitized());
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/*
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* NEEDSWORK: why does delete-refs have to be so specific to
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* send-pack machinery that set_ref_status_for_push() cannot
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* set this bit for us???
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*/
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for (ref = remote_refs; ref; ref = ref->next)
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if (ref->deletion && !allow_deleting_refs)
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ref->status = REF_STATUS_REJECT_NODELETE;
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if (!args->dry_run)
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advertise_shallow_grafts_buf(&req_buf);
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if (!args->dry_run && args->push_cert)
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cmds_sent = generate_push_cert(&req_buf, remote_refs, args,
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cap_buf.buf, push_cert_nonce);
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/*
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* Clear the status for each ref and see if we need to send
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* the pack data.
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*/
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for (ref = remote_refs; ref; ref = ref->next) {
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if (!ref_update_to_be_sent(ref, args))
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continue;
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if (!ref->deletion)
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need_pack_data = 1;
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if (args->dry_run || !status_report)
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ref->status = REF_STATUS_OK;
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else
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ref->status = REF_STATUS_EXPECTING_REPORT;
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}
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/*
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* Finally, tell the other end!
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*/
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for (ref = remote_refs; ref; ref = ref->next) {
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char *old_hex, *new_hex;
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if (args->dry_run || args->push_cert)
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continue;
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if (!ref_update_to_be_sent(ref, args))
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continue;
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old_hex = sha1_to_hex(ref->old_sha1);
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new_hex = sha1_to_hex(ref->new_sha1);
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if (!cmds_sent) {
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packet_buf_write(&req_buf,
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"%s %s %s%c%s",
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old_hex, new_hex, ref->name, 0,
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cap_buf.buf);
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cmds_sent = 1;
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} else {
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packet_buf_write(&req_buf, "%s %s %s",
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old_hex, new_hex, ref->name);
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}
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}
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if (args->stateless_rpc) {
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if (!args->dry_run && (cmds_sent || is_repository_shallow())) {
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packet_buf_flush(&req_buf);
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send_sideband(out, -1, req_buf.buf, req_buf.len, LARGE_PACKET_MAX);
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}
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} else {
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write_or_die(out, req_buf.buf, req_buf.len);
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packet_flush(out);
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}
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strbuf_release(&req_buf);
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strbuf_release(&cap_buf);
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if (use_sideband && cmds_sent) {
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memset(&demux, 0, sizeof(demux));
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demux.proc = sideband_demux;
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demux.data = fd;
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demux.out = -1;
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if (start_async(&demux))
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die("send-pack: unable to fork off sideband demultiplexer");
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in = demux.out;
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}
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if (need_pack_data && cmds_sent) {
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if (pack_objects(out, remote_refs, extra_have, args) < 0) {
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for (ref = remote_refs; ref; ref = ref->next)
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ref->status = REF_STATUS_NONE;
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if (args->stateless_rpc)
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close(out);
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if (git_connection_is_socket(conn))
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shutdown(fd[0], SHUT_WR);
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if (use_sideband)
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finish_async(&demux);
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fd[1] = -1;
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return -1;
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}
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if (!args->stateless_rpc)
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/* Closed by pack_objects() via start_command() */
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fd[1] = -1;
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}
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if (args->stateless_rpc && cmds_sent)
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packet_flush(out);
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if (status_report && cmds_sent)
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ret = receive_status(in, remote_refs);
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else
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ret = 0;
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if (args->stateless_rpc)
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packet_flush(out);
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if (use_sideband && cmds_sent) {
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if (finish_async(&demux)) {
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error("error in sideband demultiplexer");
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ret = -1;
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}
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close(demux.out);
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}
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if (ret < 0)
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return ret;
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if (args->porcelain)
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return 0;
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for (ref = remote_refs; ref; ref = ref->next) {
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switch (ref->status) {
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case REF_STATUS_NONE:
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case REF_STATUS_UPTODATE:
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case REF_STATUS_OK:
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break;
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default:
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return -1;
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}
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}
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return 0;
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}
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