2012-10-26 23:53:53 +08:00
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#include "builtin.h"
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2017-06-15 02:07:36 +08:00
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#include "config.h"
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2012-10-26 23:53:53 +08:00
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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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2013-07-09 04:56:53 +08:00
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#include "connect.h"
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2012-10-26 23:53:53 +08:00
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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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2013-12-05 21:02:29 +08:00
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#include "sha1-array.h"
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push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
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#include "gpg-interface.h"
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2015-08-19 23:26:46 +08:00
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#include "cache.h"
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int option_parse_push_signed(const struct option *opt,
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const char *arg, int unset)
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{
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if (unset) {
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*(int *)(opt->value) = SEND_PACK_PUSH_CERT_NEVER;
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return 0;
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}
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switch (git_parse_maybe_bool(arg)) {
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case 1:
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*(int *)(opt->value) = SEND_PACK_PUSH_CERT_ALWAYS;
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return 0;
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case 0:
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*(int *)(opt->value) = SEND_PACK_PUSH_CERT_NEVER;
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return 0;
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}
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if (!strcasecmp("if-asked", arg)) {
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*(int *)(opt->value) = SEND_PACK_PUSH_CERT_IF_ASKED;
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return 0;
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}
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die("bad %s argument: %s", opt->long_name, arg);
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}
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2012-10-26 23:53:53 +08:00
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2016-06-09 03:42:16 +08:00
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static void feed_object(const unsigned char *sha1, FILE *fh, int negative)
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2012-10-26 23:53:53 +08:00
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{
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if (negative && !has_sha1_file(sha1))
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2016-06-09 03:42:16 +08:00
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return;
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2012-10-26 23:53:53 +08:00
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if (negative)
|
2016-06-09 03:42:16 +08:00
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putc('^', fh);
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fputs(sha1_to_hex(sha1), fh);
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putc('\n', fh);
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2012-10-26 23:53:53 +08:00
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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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2017-03-31 09:40:00 +08:00
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static int pack_objects(int fd, struct ref *refs, struct oid_array *extra, struct send_pack_args *args)
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2012-10-26 23:53:53 +08:00
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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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2014-12-25 07:05:40 +08:00
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NULL,
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2012-10-26 23:53:53 +08:00
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};
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2014-08-20 03:09:35 +08:00
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struct child_process po = CHILD_PROCESS_INIT;
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2016-06-09 03:42:16 +08:00
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FILE *po_in;
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2012-10-26 23:53:53 +08:00
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int i;
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2017-03-07 21:39:48 +08:00
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int rc;
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2012-10-26 23:53:53 +08:00
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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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2014-12-25 07:05:40 +08:00
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if (is_repository_shallow())
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argv[i++] = "--shallow";
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2012-10-26 23:53:53 +08:00
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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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2016-06-09 03:42:16 +08:00
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po_in = xfdopen(po.in, "w");
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2012-10-26 23:53:53 +08:00
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for (i = 0; i < extra->nr; i++)
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2017-03-27 00:01:37 +08:00
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feed_object(extra->oid[i].hash, po_in, 1);
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2012-10-26 23:53:53 +08:00
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while (refs) {
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2016-06-09 03:42:16 +08:00
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if (!is_null_oid(&refs->old_oid))
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feed_object(refs->old_oid.hash, po_in, 1);
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if (!is_null_oid(&refs->new_oid))
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feed_object(refs->new_oid.hash, po_in, 0);
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2012-10-26 23:53:53 +08:00
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refs = refs->next;
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}
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2016-06-09 03:42:16 +08:00
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fflush(po_in);
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if (ferror(po_in))
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die_errno("error writing to pack-objects");
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fclose(po_in);
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2012-10-26 23:53:53 +08:00
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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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2017-03-07 21:39:48 +08:00
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rc = finish_command(&po);
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if (rc) {
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/*
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* For a normal non-zero exit, we assume pack-objects wrote
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* something useful to stderr. For death by signal, though,
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* we should mention it to the user. The exception is SIGPIPE
|
2017-06-25 18:20:41 +08:00
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* (141), because that's a normal occurrence if the remote end
|
2017-03-07 21:39:48 +08:00
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* hangs up (and we'll report that by trying to read the unpack
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* status).
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*/
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if (rc > 128 && rc != 141)
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error("pack-objects died of signal %d", rc - 128);
|
2012-10-26 23:53:53 +08:00
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return -1;
|
2017-03-07 21:39:48 +08:00
|
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}
|
2012-10-26 23:53:53 +08:00
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return 0;
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}
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|
2017-03-07 21:35:57 +08:00
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static int receive_unpack_status(int in)
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2012-10-26 23:53:53 +08:00
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{
|
2017-03-07 21:35:57 +08:00
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const char *line = packet_read_line(in, NULL);
|
2017-03-07 21:36:19 +08:00
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if (!skip_prefix(line, "unpack ", &line))
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2017-03-07 21:37:36 +08:00
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return error(_("unable to parse remote unpack status: %s"), line);
|
2017-03-07 21:36:19 +08:00
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if (strcmp(line, "ok"))
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2017-03-07 21:37:36 +08:00
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return error(_("remote unpack failed: %s"), line);
|
2017-03-07 21:35:57 +08:00
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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;
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|
2012-10-26 23:53:53 +08:00
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hint = NULL;
|
2017-03-07 21:35:57 +08:00
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ret = receive_unpack_status(in);
|
2012-10-26 23:53:53 +08:00
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while (1) {
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char *refname;
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char *msg;
|
2017-03-07 21:35:57 +08:00
|
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char *line = packet_read_line(in, NULL);
|
pkt-line: provide a LARGE_PACKET_MAX static buffer
Most of the callers of packet_read_line just read into a
static 1000-byte buffer (callers which handle arbitrary
binary data already use LARGE_PACKET_MAX). This works fine
in practice, because:
1. The only variable-sized data in these lines is a ref
name, and refs tend to be a lot shorter than 1000
characters.
2. When sending ref lines, git-core always limits itself
to 1000 byte packets.
However, the only limit given in the protocol specification
in Documentation/technical/protocol-common.txt is
LARGE_PACKET_MAX; the 1000 byte limit is mentioned only in
pack-protocol.txt, and then only describing what we write,
not as a specific limit for readers.
This patch lets us bump the 1000-byte limit to
LARGE_PACKET_MAX. Even though git-core will never write a
packet where this makes a difference, there are two good
reasons to do this:
1. Other git implementations may have followed
protocol-common.txt and used a larger maximum size. We
don't bump into it in practice because it would involve
very long ref names.
2. We may want to increase the 1000-byte limit one day.
Since packets are transferred before any capabilities,
it's difficult to do this in a backwards-compatible
way. But if we bump the size of buffer the readers can
handle, eventually older versions of git will be
obsolete enough that we can justify bumping the
writers, as well. We don't have plans to do this
anytime soon, but there is no reason not to start the
clock ticking now.
Just bumping all of the reading bufs to LARGE_PACKET_MAX
would waste memory. Instead, since most readers just read
into a temporary buffer anyway, let's provide a single
static buffer that all callers can use. We can further wrap
this detail away by having the packet_read_line wrapper just
use the buffer transparently and return a pointer to the
static storage. That covers most of the cases, and the
remaining ones already read into their own LARGE_PACKET_MAX
buffers.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-02-21 04:02:57 +08:00
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if (!line)
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2012-10-26 23:53:53 +08:00
|
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break;
|
2013-12-01 04:55:40 +08:00
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if (!starts_with(line, "ok ") && !starts_with(line, "ng ")) {
|
2013-02-21 04:00:43 +08:00
|
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|
error("invalid ref status from remote: %s", line);
|
2012-10-26 23:53:53 +08:00
|
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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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|
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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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|
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if (hint)
|
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|
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hint = find_ref_by_name(hint, refname);
|
|
|
|
|
if (!hint)
|
|
|
|
|
hint = find_ref_by_name(refs, refname);
|
|
|
|
|
if (!hint) {
|
|
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|
|
warning("remote reported status on unknown ref: %s",
|
|
|
|
|
refname);
|
|
|
|
|
continue;
|
|
|
|
|
}
|
|
|
|
|
if (hint->status != REF_STATUS_EXPECTING_REPORT) {
|
|
|
|
|
warning("remote reported status on unexpected ref: %s",
|
|
|
|
|
refname);
|
|
|
|
|
continue;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (line[0] == 'o' && line[1] == 'k')
|
|
|
|
|
hint->status = REF_STATUS_OK;
|
|
|
|
|
else {
|
|
|
|
|
hint->status = REF_STATUS_REMOTE_REJECT;
|
|
|
|
|
ret = -1;
|
|
|
|
|
}
|
2016-10-13 02:20:23 +08:00
|
|
|
hint->remote_status = xstrdup_or_null(msg);
|
2012-10-26 23:53:53 +08:00
|
|
|
/* start our next search from the next ref */
|
|
|
|
|
hint = hint->next;
|
|
|
|
|
}
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static int sideband_demux(int in, int out, void *data)
|
|
|
|
|
{
|
|
|
|
|
int *fd = data, ret;
|
|
|
|
|
#ifdef NO_PTHREADS
|
|
|
|
|
close(fd[1]);
|
|
|
|
|
#endif
|
|
|
|
|
ret = recv_sideband("send-pack", fd[0], out);
|
|
|
|
|
close(out);
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
2013-12-05 21:02:52 +08:00
|
|
|
static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
|
|
|
|
|
{
|
|
|
|
|
struct strbuf *sb = cb;
|
|
|
|
|
if (graft->nr_parent == -1)
|
2015-03-14 07:39:34 +08:00
|
|
|
packet_buf_write(sb, "shallow %s\n", oid_to_hex(&graft->oid));
|
2013-12-05 21:02:52 +08:00
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2014-01-06 07:55:01 +08:00
|
|
|
static void advertise_shallow_grafts_buf(struct strbuf *sb)
|
2013-12-05 21:02:52 +08:00
|
|
|
{
|
|
|
|
|
if (!is_repository_shallow())
|
|
|
|
|
return;
|
|
|
|
|
for_each_commit_graft(advertise_shallow_grafts_cb, sb);
|
|
|
|
|
}
|
|
|
|
|
|
2015-01-08 11:23:21 +08:00
|
|
|
#define CHECK_REF_NO_PUSH -1
|
|
|
|
|
#define CHECK_REF_STATUS_REJECTED -2
|
|
|
|
|
#define CHECK_REF_UPTODATE -3
|
|
|
|
|
static int check_to_send_update(const struct ref *ref, const struct send_pack_args *args)
|
2014-08-13 06:40:00 +08:00
|
|
|
{
|
|
|
|
|
if (!ref->peer_ref && !args->send_mirror)
|
2015-01-08 11:23:21 +08:00
|
|
|
return CHECK_REF_NO_PUSH;
|
2014-08-13 06:40:00 +08:00
|
|
|
|
|
|
|
|
/* Check for statuses set by set_ref_status_for_push() */
|
|
|
|
|
switch (ref->status) {
|
|
|
|
|
case REF_STATUS_REJECT_NONFASTFORWARD:
|
|
|
|
|
case REF_STATUS_REJECT_ALREADY_EXISTS:
|
|
|
|
|
case REF_STATUS_REJECT_FETCH_FIRST:
|
|
|
|
|
case REF_STATUS_REJECT_NEEDS_FORCE:
|
|
|
|
|
case REF_STATUS_REJECT_STALE:
|
|
|
|
|
case REF_STATUS_REJECT_NODELETE:
|
2015-01-08 11:23:21 +08:00
|
|
|
return CHECK_REF_STATUS_REJECTED;
|
2014-08-13 06:40:00 +08:00
|
|
|
case REF_STATUS_UPTODATE:
|
2015-01-08 11:23:21 +08:00
|
|
|
return CHECK_REF_UPTODATE;
|
2014-08-13 06:40:00 +08:00
|
|
|
default:
|
2015-01-08 11:23:21 +08:00
|
|
|
return 0;
|
2014-08-13 06:40:00 +08:00
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
/*
|
|
|
|
|
* the beginning of the next line, or the end of buffer.
|
|
|
|
|
*
|
|
|
|
|
* NEEDSWORK: perhaps move this to git-compat-util.h or somewhere and
|
|
|
|
|
* convert many similar uses found by "git grep -A4 memchr".
|
|
|
|
|
*/
|
|
|
|
|
static const char *next_line(const char *line, size_t len)
|
|
|
|
|
{
|
|
|
|
|
const char *nl = memchr(line, '\n', len);
|
|
|
|
|
if (!nl)
|
|
|
|
|
return line + len; /* incomplete line */
|
|
|
|
|
return nl + 1;
|
|
|
|
|
}
|
|
|
|
|
|
2014-08-19 04:46:58 +08:00
|
|
|
static int generate_push_cert(struct strbuf *req_buf,
|
|
|
|
|
const struct ref *remote_refs,
|
|
|
|
|
struct send_pack_args *args,
|
2014-08-22 07:45:30 +08:00
|
|
|
const char *cap_string,
|
|
|
|
|
const char *push_cert_nonce)
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
{
|
|
|
|
|
const struct ref *ref;
|
2016-07-15 05:49:47 +08:00
|
|
|
struct string_list_item *item;
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
char *signing_key = xstrdup(get_signing_key());
|
|
|
|
|
const char *cp, *np;
|
|
|
|
|
struct strbuf cert = STRBUF_INIT;
|
|
|
|
|
int update_seen = 0;
|
|
|
|
|
|
2016-07-31 01:36:23 +08:00
|
|
|
strbuf_addstr(&cert, "certificate version 0.1\n");
|
2014-10-09 04:05:15 +08:00
|
|
|
strbuf_addf(&cert, "pusher %s ", signing_key);
|
|
|
|
|
datestamp(&cert);
|
|
|
|
|
strbuf_addch(&cert, '\n');
|
2014-08-23 09:15:24 +08:00
|
|
|
if (args->url && *args->url) {
|
|
|
|
|
char *anon_url = transport_anonymize_url(args->url);
|
|
|
|
|
strbuf_addf(&cert, "pushee %s\n", anon_url);
|
|
|
|
|
free(anon_url);
|
|
|
|
|
}
|
2014-08-22 07:45:30 +08:00
|
|
|
if (push_cert_nonce[0])
|
|
|
|
|
strbuf_addf(&cert, "nonce %s\n", push_cert_nonce);
|
2016-07-15 05:49:47 +08:00
|
|
|
if (args->push_options)
|
|
|
|
|
for_each_string_list_item(item, args->push_options)
|
|
|
|
|
strbuf_addf(&cert, "push-option %s\n", item->string);
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
strbuf_addstr(&cert, "\n");
|
|
|
|
|
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next) {
|
2015-01-08 11:23:21 +08:00
|
|
|
if (check_to_send_update(ref, args) < 0)
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
continue;
|
|
|
|
|
update_seen = 1;
|
|
|
|
|
strbuf_addf(&cert, "%s %s %s\n",
|
2015-11-10 10:22:20 +08:00
|
|
|
oid_to_hex(&ref->old_oid),
|
|
|
|
|
oid_to_hex(&ref->new_oid),
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
ref->name);
|
|
|
|
|
}
|
|
|
|
|
if (!update_seen)
|
|
|
|
|
goto free_return;
|
|
|
|
|
|
|
|
|
|
if (sign_buffer(&cert, &cert, signing_key))
|
|
|
|
|
die(_("failed to sign the push certificate"));
|
|
|
|
|
|
2014-08-19 04:46:58 +08:00
|
|
|
packet_buf_write(req_buf, "push-cert%c%s", 0, cap_string);
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
for (cp = cert.buf; cp < cert.buf + cert.len; cp = np) {
|
|
|
|
|
np = next_line(cp, cert.buf + cert.len - cp);
|
|
|
|
|
packet_buf_write(req_buf,
|
|
|
|
|
"%.*s", (int)(np - cp), cp);
|
|
|
|
|
}
|
|
|
|
|
packet_buf_write(req_buf, "push-cert-end\n");
|
|
|
|
|
|
|
|
|
|
free_return:
|
|
|
|
|
free(signing_key);
|
|
|
|
|
strbuf_release(&cert);
|
2014-08-19 04:46:58 +08:00
|
|
|
return update_seen;
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
}
|
|
|
|
|
|
2015-01-08 11:23:22 +08:00
|
|
|
|
|
|
|
|
static int atomic_push_failure(struct send_pack_args *args,
|
|
|
|
|
struct ref *remote_refs,
|
|
|
|
|
struct ref *failing_ref)
|
|
|
|
|
{
|
|
|
|
|
struct ref *ref;
|
|
|
|
|
/* Mark other refs as failed */
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next) {
|
|
|
|
|
if (!ref->peer_ref && !args->send_mirror)
|
|
|
|
|
continue;
|
|
|
|
|
|
|
|
|
|
switch (ref->status) {
|
|
|
|
|
case REF_STATUS_EXPECTING_REPORT:
|
|
|
|
|
ref->status = REF_STATUS_ATOMIC_PUSH_FAILED;
|
|
|
|
|
continue;
|
|
|
|
|
default:
|
|
|
|
|
break; /* do nothing */
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
return error("atomic push failed for ref %s. status: %d\n",
|
|
|
|
|
failing_ref->name, failing_ref->status);
|
|
|
|
|
}
|
|
|
|
|
|
2015-04-02 09:00:36 +08:00
|
|
|
#define NONCE_LEN_LIMIT 256
|
|
|
|
|
|
|
|
|
|
static void reject_invalid_nonce(const char *nonce, int len)
|
|
|
|
|
{
|
|
|
|
|
int i = 0;
|
|
|
|
|
|
|
|
|
|
if (NONCE_LEN_LIMIT <= len)
|
|
|
|
|
die("the receiving end asked to sign an invalid nonce <%.*s>",
|
|
|
|
|
len, nonce);
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < len; i++) {
|
|
|
|
|
int ch = nonce[i] & 0xFF;
|
|
|
|
|
if (isalnum(ch) ||
|
|
|
|
|
ch == '-' || ch == '.' ||
|
|
|
|
|
ch == '/' || ch == '+' ||
|
|
|
|
|
ch == '=' || ch == '_')
|
|
|
|
|
continue;
|
|
|
|
|
die("the receiving end asked to sign an invalid nonce <%.*s>",
|
|
|
|
|
len, nonce);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
2012-10-26 23:53:53 +08:00
|
|
|
int send_pack(struct send_pack_args *args,
|
|
|
|
|
int fd[], struct child_process *conn,
|
|
|
|
|
struct ref *remote_refs,
|
2017-03-31 09:40:00 +08:00
|
|
|
struct oid_array *extra_have)
|
2012-10-26 23:53:53 +08:00
|
|
|
{
|
|
|
|
|
int in = fd[0];
|
|
|
|
|
int out = fd[1];
|
|
|
|
|
struct strbuf req_buf = STRBUF_INIT;
|
2014-08-16 02:37:01 +08:00
|
|
|
struct strbuf cap_buf = STRBUF_INIT;
|
2012-10-26 23:53:53 +08:00
|
|
|
struct ref *ref;
|
2014-08-16 03:23:51 +08:00
|
|
|
int need_pack_data = 0;
|
2012-10-26 23:53:53 +08:00
|
|
|
int allow_deleting_refs = 0;
|
|
|
|
|
int status_report = 0;
|
|
|
|
|
int use_sideband = 0;
|
|
|
|
|
int quiet_supported = 0;
|
|
|
|
|
int agent_supported = 0;
|
2015-01-08 11:23:22 +08:00
|
|
|
int use_atomic = 0;
|
|
|
|
|
int atomic_supported = 0;
|
2016-07-15 05:49:47 +08:00
|
|
|
int use_push_options = 0;
|
|
|
|
|
int push_options_supported = 0;
|
2012-10-26 23:53:53 +08:00
|
|
|
unsigned cmds_sent = 0;
|
|
|
|
|
int ret;
|
|
|
|
|
struct async demux;
|
2014-08-22 07:45:30 +08:00
|
|
|
const char *push_cert_nonce = NULL;
|
2012-10-26 23:53:53 +08:00
|
|
|
|
|
|
|
|
/* Does the other end support the reporting? */
|
|
|
|
|
if (server_supports("report-status"))
|
|
|
|
|
status_report = 1;
|
|
|
|
|
if (server_supports("delete-refs"))
|
|
|
|
|
allow_deleting_refs = 1;
|
|
|
|
|
if (server_supports("ofs-delta"))
|
|
|
|
|
args->use_ofs_delta = 1;
|
|
|
|
|
if (server_supports("side-band-64k"))
|
|
|
|
|
use_sideband = 1;
|
|
|
|
|
if (server_supports("quiet"))
|
|
|
|
|
quiet_supported = 1;
|
|
|
|
|
if (server_supports("agent"))
|
|
|
|
|
agent_supported = 1;
|
2013-11-24 00:07:55 +08:00
|
|
|
if (server_supports("no-thin"))
|
|
|
|
|
args->use_thin_pack = 0;
|
2015-01-08 11:23:22 +08:00
|
|
|
if (server_supports("atomic"))
|
|
|
|
|
atomic_supported = 1;
|
2016-07-15 05:49:47 +08:00
|
|
|
if (server_supports("push-options"))
|
|
|
|
|
push_options_supported = 1;
|
2014-08-22 07:45:30 +08:00
|
|
|
|
2015-08-19 23:26:46 +08:00
|
|
|
if (args->push_cert != SEND_PACK_PUSH_CERT_NEVER) {
|
|
|
|
|
int len;
|
2014-08-22 07:45:30 +08:00
|
|
|
push_cert_nonce = server_feature_value("push-cert", &len);
|
2015-08-19 23:26:46 +08:00
|
|
|
if (push_cert_nonce) {
|
|
|
|
|
reject_invalid_nonce(push_cert_nonce, len);
|
|
|
|
|
push_cert_nonce = xmemdupz(push_cert_nonce, len);
|
|
|
|
|
} else if (args->push_cert == SEND_PACK_PUSH_CERT_ALWAYS) {
|
2014-08-22 07:45:30 +08:00
|
|
|
die(_("the receiving end does not support --signed push"));
|
2015-08-19 23:26:46 +08:00
|
|
|
} else if (args->push_cert == SEND_PACK_PUSH_CERT_IF_ASKED) {
|
|
|
|
|
warning(_("not sending a push certificate since the"
|
|
|
|
|
" receiving end does not support --signed"
|
|
|
|
|
" push"));
|
|
|
|
|
}
|
2014-08-22 07:45:30 +08:00
|
|
|
}
|
2012-10-26 23:53:53 +08:00
|
|
|
|
|
|
|
|
if (!remote_refs) {
|
|
|
|
|
fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
|
|
|
|
|
"Perhaps you should specify a branch such as 'master'.\n");
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
2015-01-08 11:23:22 +08:00
|
|
|
if (args->atomic && !atomic_supported)
|
2015-04-03 01:28:48 +08:00
|
|
|
die(_("the receiving end does not support --atomic push"));
|
2015-01-08 11:23:22 +08:00
|
|
|
|
|
|
|
|
use_atomic = atomic_supported && args->atomic;
|
2012-10-26 23:53:53 +08:00
|
|
|
|
2016-07-15 05:49:47 +08:00
|
|
|
if (args->push_options && !push_options_supported)
|
|
|
|
|
die(_("the receiving end does not support push options"));
|
|
|
|
|
|
|
|
|
|
use_push_options = push_options_supported && args->push_options;
|
|
|
|
|
|
2014-08-16 02:37:01 +08:00
|
|
|
if (status_report)
|
|
|
|
|
strbuf_addstr(&cap_buf, " report-status");
|
|
|
|
|
if (use_sideband)
|
|
|
|
|
strbuf_addstr(&cap_buf, " side-band-64k");
|
|
|
|
|
if (quiet_supported && (args->quiet || !args->progress))
|
|
|
|
|
strbuf_addstr(&cap_buf, " quiet");
|
2015-01-08 11:23:22 +08:00
|
|
|
if (use_atomic)
|
|
|
|
|
strbuf_addstr(&cap_buf, " atomic");
|
2016-07-15 05:49:47 +08:00
|
|
|
if (use_push_options)
|
|
|
|
|
strbuf_addstr(&cap_buf, " push-options");
|
2014-08-16 02:37:01 +08:00
|
|
|
if (agent_supported)
|
|
|
|
|
strbuf_addf(&cap_buf, " agent=%s", git_user_agent_sanitized());
|
|
|
|
|
|
2014-08-13 06:04:17 +08:00
|
|
|
/*
|
|
|
|
|
* NEEDSWORK: why does delete-refs have to be so specific to
|
|
|
|
|
* send-pack machinery that set_ref_status_for_push() cannot
|
|
|
|
|
* set this bit for us???
|
|
|
|
|
*/
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next)
|
|
|
|
|
if (ref->deletion && !allow_deleting_refs)
|
|
|
|
|
ref->status = REF_STATUS_REJECT_NODELETE;
|
|
|
|
|
|
2013-12-05 21:02:44 +08:00
|
|
|
if (!args->dry_run)
|
2013-12-05 21:02:52 +08:00
|
|
|
advertise_shallow_grafts_buf(&req_buf);
|
2013-12-05 21:02:44 +08:00
|
|
|
|
2015-08-19 23:26:46 +08:00
|
|
|
if (!args->dry_run && push_cert_nonce)
|
2014-08-19 04:46:58 +08:00
|
|
|
cmds_sent = generate_push_cert(&req_buf, remote_refs, args,
|
2014-08-22 07:45:30 +08:00
|
|
|
cap_buf.buf, push_cert_nonce);
|
push: the beginning of "git push --signed"
While signed tags and commits assert that the objects thusly signed
came from you, who signed these objects, there is not a good way to
assert that you wanted to have a particular object at the tip of a
particular branch. My signing v2.0.1 tag only means I want to call
the version v2.0.1, and it does not mean I want to push it out to my
'master' branch---it is likely that I only want it in 'maint', so
the signature on the object alone is insufficient.
The only assurance to you that 'maint' points at what I wanted to
place there comes from your trust on the hosting site and my
authentication with it, which cannot easily audited later.
Introduce a mechanism that allows you to sign a "push certificate"
(for the lack of better name) every time you push, asserting that
what object you are pushing to update which ref that used to point
at what other object. Think of it as a cryptographic protection for
ref updates, similar to signed tags/commits but working on an
orthogonal axis.
The basic flow based on this mechanism goes like this:
1. You push out your work with "git push --signed".
2. The sending side learns where the remote refs are as usual,
together with what protocol extension the receiving end
supports. If the receiving end does not advertise the protocol
extension "push-cert", an attempt to "git push --signed" fails.
Otherwise, a text file, that looks like the following, is
prepared in core:
certificate version 0.1
pusher Junio C Hamano <gitster@pobox.com> 1315427886 -0700
7339ca65... 21580ecb... refs/heads/master
3793ac56... 12850bec... refs/heads/next
The file begins with a few header lines, which may grow as we
gain more experience. The 'pusher' header records the name of
the signer (the value of user.signingkey configuration variable,
falling back to GIT_COMMITTER_{NAME|EMAIL}) and the time of the
certificate generation. After the header, a blank line follows,
followed by a copy of the protocol message lines.
Each line shows the old and the new object name at the tip of
the ref this push tries to update, in the way identical to how
the underlying "git push" protocol exchange tells the ref
updates to the receiving end (by recording the "old" object
name, the push certificate also protects against replaying). It
is expected that new command packet types other than the
old-new-refname kind will be included in push certificate in the
same way as would appear in the plain vanilla command packets in
unsigned pushes.
The user then is asked to sign this push certificate using GPG,
formatted in a way similar to how signed tag objects are signed,
and the result is sent to the other side (i.e. receive-pack).
In the protocol exchange, this step comes immediately before the
sender tells what the result of the push should be, which in
turn comes before it sends the pack data.
3. When the receiving end sees a push certificate, the certificate
is written out as a blob. The pre-receive hook can learn about
the certificate by checking GIT_PUSH_CERT environment variable,
which, if present, tells the object name of this blob, and make
the decision to allow or reject this push. Additionally, the
post-receive hook can also look at the certificate, which may be
a good place to log all the received certificates for later
audits.
Because a push certificate carry the same information as the usual
command packets in the protocol exchange, we can omit the latter
when a push certificate is in use and reduce the protocol overhead.
This however is not included in this patch to make it easier to
review (in other words, the series at this step should never be
released without the remainder of the series, as it implements an
interim protocol that will be incompatible with the final one).
As such, the documentation update for the protocol is left out of
this step.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-09-13 02:17:07 +08:00
|
|
|
|
2012-10-26 23:53:53 +08:00
|
|
|
/*
|
2014-08-16 03:29:42 +08:00
|
|
|
* Clear the status for each ref and see if we need to send
|
|
|
|
|
* the pack data.
|
2012-10-26 23:53:53 +08:00
|
|
|
*/
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next) {
|
2015-01-08 11:23:22 +08:00
|
|
|
switch (check_to_send_update(ref, args)) {
|
|
|
|
|
case 0: /* no error */
|
|
|
|
|
break;
|
|
|
|
|
case CHECK_REF_STATUS_REJECTED:
|
|
|
|
|
/*
|
|
|
|
|
* When we know the server would reject a ref update if
|
|
|
|
|
* we were to send it and we're trying to send the refs
|
|
|
|
|
* atomically, abort the whole operation.
|
|
|
|
|
*/
|
|
|
|
|
if (use_atomic)
|
|
|
|
|
return atomic_push_failure(args, remote_refs, ref);
|
|
|
|
|
/* Fallthrough for non atomic case. */
|
|
|
|
|
default:
|
2012-10-26 23:53:53 +08:00
|
|
|
continue;
|
2015-01-08 11:23:22 +08:00
|
|
|
}
|
2012-10-26 23:53:53 +08:00
|
|
|
if (!ref->deletion)
|
2014-08-16 03:23:51 +08:00
|
|
|
need_pack_data = 1;
|
2012-10-26 23:53:53 +08:00
|
|
|
|
2014-08-16 03:29:42 +08:00
|
|
|
if (args->dry_run || !status_report)
|
2012-10-26 23:53:53 +08:00
|
|
|
ref->status = REF_STATUS_OK;
|
2014-08-16 03:29:42 +08:00
|
|
|
else
|
|
|
|
|
ref->status = REF_STATUS_EXPECTING_REPORT;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Finally, tell the other end!
|
|
|
|
|
*/
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next) {
|
|
|
|
|
char *old_hex, *new_hex;
|
|
|
|
|
|
2015-08-19 23:26:46 +08:00
|
|
|
if (args->dry_run || push_cert_nonce)
|
2012-10-26 23:53:53 +08:00
|
|
|
continue;
|
|
|
|
|
|
2015-01-08 11:23:21 +08:00
|
|
|
if (check_to_send_update(ref, args) < 0)
|
2014-08-16 03:29:42 +08:00
|
|
|
continue;
|
2012-10-26 23:53:53 +08:00
|
|
|
|
2015-11-10 10:22:20 +08:00
|
|
|
old_hex = oid_to_hex(&ref->old_oid);
|
|
|
|
|
new_hex = oid_to_hex(&ref->new_oid);
|
2014-08-20 04:02:19 +08:00
|
|
|
if (!cmds_sent) {
|
2014-08-16 03:29:42 +08:00
|
|
|
packet_buf_write(&req_buf,
|
|
|
|
|
"%s %s %s%c%s",
|
|
|
|
|
old_hex, new_hex, ref->name, 0,
|
|
|
|
|
cap_buf.buf);
|
2014-08-20 04:02:19 +08:00
|
|
|
cmds_sent = 1;
|
2012-10-26 23:53:53 +08:00
|
|
|
} else {
|
2014-08-16 03:29:42 +08:00
|
|
|
packet_buf_write(&req_buf, "%s %s %s",
|
|
|
|
|
old_hex, new_hex, ref->name);
|
2012-10-26 23:53:53 +08:00
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
2017-03-23 06:21:59 +08:00
|
|
|
if (use_push_options) {
|
|
|
|
|
struct string_list_item *item;
|
|
|
|
|
|
|
|
|
|
packet_buf_flush(&req_buf);
|
|
|
|
|
for_each_string_list_item(item, args->push_options)
|
|
|
|
|
packet_buf_write(&req_buf, "%s", item->string);
|
|
|
|
|
}
|
|
|
|
|
|
2012-10-26 23:53:53 +08:00
|
|
|
if (args->stateless_rpc) {
|
2013-12-05 21:02:52 +08:00
|
|
|
if (!args->dry_run && (cmds_sent || is_repository_shallow())) {
|
2012-10-26 23:53:53 +08:00
|
|
|
packet_buf_flush(&req_buf);
|
|
|
|
|
send_sideband(out, -1, req_buf.buf, req_buf.len, LARGE_PACKET_MAX);
|
|
|
|
|
}
|
|
|
|
|
} else {
|
2013-02-21 04:01:56 +08:00
|
|
|
write_or_die(out, req_buf.buf, req_buf.len);
|
2012-10-26 23:53:53 +08:00
|
|
|
packet_flush(out);
|
|
|
|
|
}
|
|
|
|
|
strbuf_release(&req_buf);
|
2014-08-16 02:37:01 +08:00
|
|
|
strbuf_release(&cap_buf);
|
2012-10-26 23:53:53 +08:00
|
|
|
|
|
|
|
|
if (use_sideband && cmds_sent) {
|
|
|
|
|
memset(&demux, 0, sizeof(demux));
|
|
|
|
|
demux.proc = sideband_demux;
|
|
|
|
|
demux.data = fd;
|
|
|
|
|
demux.out = -1;
|
send-pack: isolate sigpipe in demuxer thread
If we get an error from pack-objects, we may exit
send_pack() early, before reading the server's status
response. In such a case, we may racily see SIGPIPE from our
async demuxer (which is trying to write that status back to
us), and we'd prefer to continue pushing the error up the
call stack, rather than taking down the whole process with
signal death.
This is safe to do because our demuxer just calls
recv_sideband, whose data writes are all done with
write_or_die(), which will notice SIGPIPE.
We do also write sideband 2 to stderr, and we would no
longer die on SIGPIPE there (if it were piped in the first
place, and if the piped program went away). But that's
probably a good thing, as it likewise should not abort the
push process at all (neither immediately by signal, nor
eventually by reporting failure back to the main thread).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-20 06:50:17 +08:00
|
|
|
demux.isolate_sigpipe = 1;
|
2012-10-26 23:53:53 +08:00
|
|
|
if (start_async(&demux))
|
|
|
|
|
die("send-pack: unable to fork off sideband demultiplexer");
|
|
|
|
|
in = demux.out;
|
|
|
|
|
}
|
|
|
|
|
|
2014-08-16 03:23:51 +08:00
|
|
|
if (need_pack_data && cmds_sent) {
|
2012-10-26 23:53:53 +08:00
|
|
|
if (pack_objects(out, remote_refs, extra_have, args) < 0) {
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next)
|
|
|
|
|
ref->status = REF_STATUS_NONE;
|
|
|
|
|
if (args->stateless_rpc)
|
|
|
|
|
close(out);
|
|
|
|
|
if (git_connection_is_socket(conn))
|
|
|
|
|
shutdown(fd[0], SHUT_WR);
|
2017-03-07 21:38:51 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Do not even bother with the return value; we know we
|
|
|
|
|
* are failing, and just want the error() side effects.
|
|
|
|
|
*/
|
|
|
|
|
if (status_report)
|
|
|
|
|
receive_unpack_status(in);
|
|
|
|
|
|
send-pack: close demux pipe before finishing async process
This fixes a deadlock on the client side when pushing a
large number of refs from a corrupted repo. There's a
reproduction script below, but let's start with a
human-readable explanation.
The client side of a push goes something like this:
1. Start an async process to demux sideband coming from
the server.
2. Run pack-objects to send the actual pack, and wait for
its status via finish_command().
3. If pack-objects failed, abort immediately.
4. If pack-objects succeeded, read the per-ref status from
the server, which is actually coming over a pipe from
the demux process started in step 1.
We run finish_async() to wait for and clean up the demux
process in two places. In step 3, if we see an error, we
want it to end early. And after step 4, it should be done
writing any data and we are just cleaning it up.
Let's focus on the error case first. We hand the output
descriptor to the server over to pack-objects. So by the
time it has returned an error to us, it has closed the
descriptor and the server has gotten EOF. The server will
mark all refs as failed with "unpacker error" and send us
back the status for each (followed by EOF).
This status goes to the demuxer thread, which relays it over
a pipe to the main thread. But the main thread never even
tries reading the status. It's trying to bail because of the
pack-objects error, and is waiting for the demuxer thread to
finish. If there are a small number of refs, that's OK; the
demuxer thread writes into the pipe buffer, sees EOF from
the server, and quits. But if there are a large number of
refs, it may block on write() back to the main thread,
leading to a deadlock (the main thread is waiting for the
demuxer to finish, the demuxer is waiting for the main
thread to read).
We can break this deadlock by closing the pipe between the
demuxer and the main thread before calling finish_async().
Then the demuxer gets a write() error and exits.
The non-error case usually just works, because we will have
read all of the data from the other side. We do close
demux.out already, but we only do so _after_ calling
finish_async(). This is OK because there shouldn't be any
more data coming from the server. But technically we've only
read to a flush packet, and a broken or malicious server
could be sending more cruft. In such a case, we would hit
the same deadlock. Closing the pipe first doesn't affect the
normal case, and means that for a cruft-sending server,
we'll notice a write() error rather than deadlocking.
Note that when write() sees this error, we'll actually
deliver SIGPIPE to the thread, which will take down the
whole process (unless we're compiled with NO_PTHREADS). This
isn't ideal, but it's an improvement over the status quo,
which is deadlocking. And SIGPIPE handling in async threads
is a bigger problem that we can deal with separately.
A simple reproduction for the error case is below. It's
technically racy (we could exit the main process and take
down the async thread with us before it even reads the
status), though in practice it seems to fail pretty
consistently.
git init repo &&
cd repo &&
# make some commits; we need two so we can simulate corruption
# in the history later.
git commit --allow-empty -m one &&
one=$(git rev-parse HEAD) &&
git commit --allow-empty -m two &&
two=$(git rev-parse HEAD) &&
# now make a ton of refs; our goal here is to overflow the pipe buffer
# when reporting the ref status, which will cause the demuxer to block
# on write()
for i in $(seq 20000); do
echo "create refs/heads/this-is-a-really-long-branch-name-$i $two"
done |
git update-ref --stdin &&
# now make a corruption in the history such that pack-objects will fail
rm -vf .git/objects/$(echo $one | sed 's}..}&/}') &&
# and then push the result
git init --bare dst.git &&
git push --mirror dst.git
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-20 06:45:17 +08:00
|
|
|
if (use_sideband) {
|
|
|
|
|
close(demux.out);
|
2012-10-26 23:53:53 +08:00
|
|
|
finish_async(&demux);
|
send-pack: close demux pipe before finishing async process
This fixes a deadlock on the client side when pushing a
large number of refs from a corrupted repo. There's a
reproduction script below, but let's start with a
human-readable explanation.
The client side of a push goes something like this:
1. Start an async process to demux sideband coming from
the server.
2. Run pack-objects to send the actual pack, and wait for
its status via finish_command().
3. If pack-objects failed, abort immediately.
4. If pack-objects succeeded, read the per-ref status from
the server, which is actually coming over a pipe from
the demux process started in step 1.
We run finish_async() to wait for and clean up the demux
process in two places. In step 3, if we see an error, we
want it to end early. And after step 4, it should be done
writing any data and we are just cleaning it up.
Let's focus on the error case first. We hand the output
descriptor to the server over to pack-objects. So by the
time it has returned an error to us, it has closed the
descriptor and the server has gotten EOF. The server will
mark all refs as failed with "unpacker error" and send us
back the status for each (followed by EOF).
This status goes to the demuxer thread, which relays it over
a pipe to the main thread. But the main thread never even
tries reading the status. It's trying to bail because of the
pack-objects error, and is waiting for the demuxer thread to
finish. If there are a small number of refs, that's OK; the
demuxer thread writes into the pipe buffer, sees EOF from
the server, and quits. But if there are a large number of
refs, it may block on write() back to the main thread,
leading to a deadlock (the main thread is waiting for the
demuxer to finish, the demuxer is waiting for the main
thread to read).
We can break this deadlock by closing the pipe between the
demuxer and the main thread before calling finish_async().
Then the demuxer gets a write() error and exits.
The non-error case usually just works, because we will have
read all of the data from the other side. We do close
demux.out already, but we only do so _after_ calling
finish_async(). This is OK because there shouldn't be any
more data coming from the server. But technically we've only
read to a flush packet, and a broken or malicious server
could be sending more cruft. In such a case, we would hit
the same deadlock. Closing the pipe first doesn't affect the
normal case, and means that for a cruft-sending server,
we'll notice a write() error rather than deadlocking.
Note that when write() sees this error, we'll actually
deliver SIGPIPE to the thread, which will take down the
whole process (unless we're compiled with NO_PTHREADS). This
isn't ideal, but it's an improvement over the status quo,
which is deadlocking. And SIGPIPE handling in async threads
is a bigger problem that we can deal with separately.
A simple reproduction for the error case is below. It's
technically racy (we could exit the main process and take
down the async thread with us before it even reads the
status), though in practice it seems to fail pretty
consistently.
git init repo &&
cd repo &&
# make some commits; we need two so we can simulate corruption
# in the history later.
git commit --allow-empty -m one &&
one=$(git rev-parse HEAD) &&
git commit --allow-empty -m two &&
two=$(git rev-parse HEAD) &&
# now make a ton of refs; our goal here is to overflow the pipe buffer
# when reporting the ref status, which will cause the demuxer to block
# on write()
for i in $(seq 20000); do
echo "create refs/heads/this-is-a-really-long-branch-name-$i $two"
done |
git update-ref --stdin &&
# now make a corruption in the history such that pack-objects will fail
rm -vf .git/objects/$(echo $one | sed 's}..}&/}') &&
# and then push the result
git init --bare dst.git &&
git push --mirror dst.git
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-20 06:45:17 +08:00
|
|
|
}
|
2013-10-22 21:36:02 +08:00
|
|
|
fd[1] = -1;
|
2012-10-26 23:53:53 +08:00
|
|
|
return -1;
|
|
|
|
|
}
|
2013-10-22 21:36:02 +08:00
|
|
|
if (!args->stateless_rpc)
|
|
|
|
|
/* Closed by pack_objects() via start_command() */
|
|
|
|
|
fd[1] = -1;
|
2012-10-26 23:53:53 +08:00
|
|
|
}
|
|
|
|
|
if (args->stateless_rpc && cmds_sent)
|
|
|
|
|
packet_flush(out);
|
|
|
|
|
|
|
|
|
|
if (status_report && cmds_sent)
|
|
|
|
|
ret = receive_status(in, remote_refs);
|
|
|
|
|
else
|
|
|
|
|
ret = 0;
|
|
|
|
|
if (args->stateless_rpc)
|
|
|
|
|
packet_flush(out);
|
|
|
|
|
|
|
|
|
|
if (use_sideband && cmds_sent) {
|
send-pack: close demux pipe before finishing async process
This fixes a deadlock on the client side when pushing a
large number of refs from a corrupted repo. There's a
reproduction script below, but let's start with a
human-readable explanation.
The client side of a push goes something like this:
1. Start an async process to demux sideband coming from
the server.
2. Run pack-objects to send the actual pack, and wait for
its status via finish_command().
3. If pack-objects failed, abort immediately.
4. If pack-objects succeeded, read the per-ref status from
the server, which is actually coming over a pipe from
the demux process started in step 1.
We run finish_async() to wait for and clean up the demux
process in two places. In step 3, if we see an error, we
want it to end early. And after step 4, it should be done
writing any data and we are just cleaning it up.
Let's focus on the error case first. We hand the output
descriptor to the server over to pack-objects. So by the
time it has returned an error to us, it has closed the
descriptor and the server has gotten EOF. The server will
mark all refs as failed with "unpacker error" and send us
back the status for each (followed by EOF).
This status goes to the demuxer thread, which relays it over
a pipe to the main thread. But the main thread never even
tries reading the status. It's trying to bail because of the
pack-objects error, and is waiting for the demuxer thread to
finish. If there are a small number of refs, that's OK; the
demuxer thread writes into the pipe buffer, sees EOF from
the server, and quits. But if there are a large number of
refs, it may block on write() back to the main thread,
leading to a deadlock (the main thread is waiting for the
demuxer to finish, the demuxer is waiting for the main
thread to read).
We can break this deadlock by closing the pipe between the
demuxer and the main thread before calling finish_async().
Then the demuxer gets a write() error and exits.
The non-error case usually just works, because we will have
read all of the data from the other side. We do close
demux.out already, but we only do so _after_ calling
finish_async(). This is OK because there shouldn't be any
more data coming from the server. But technically we've only
read to a flush packet, and a broken or malicious server
could be sending more cruft. In such a case, we would hit
the same deadlock. Closing the pipe first doesn't affect the
normal case, and means that for a cruft-sending server,
we'll notice a write() error rather than deadlocking.
Note that when write() sees this error, we'll actually
deliver SIGPIPE to the thread, which will take down the
whole process (unless we're compiled with NO_PTHREADS). This
isn't ideal, but it's an improvement over the status quo,
which is deadlocking. And SIGPIPE handling in async threads
is a bigger problem that we can deal with separately.
A simple reproduction for the error case is below. It's
technically racy (we could exit the main process and take
down the async thread with us before it even reads the
status), though in practice it seems to fail pretty
consistently.
git init repo &&
cd repo &&
# make some commits; we need two so we can simulate corruption
# in the history later.
git commit --allow-empty -m one &&
one=$(git rev-parse HEAD) &&
git commit --allow-empty -m two &&
two=$(git rev-parse HEAD) &&
# now make a ton of refs; our goal here is to overflow the pipe buffer
# when reporting the ref status, which will cause the demuxer to block
# on write()
for i in $(seq 20000); do
echo "create refs/heads/this-is-a-really-long-branch-name-$i $two"
done |
git update-ref --stdin &&
# now make a corruption in the history such that pack-objects will fail
rm -vf .git/objects/$(echo $one | sed 's}..}&/}') &&
# and then push the result
git init --bare dst.git &&
git push --mirror dst.git
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-04-20 06:45:17 +08:00
|
|
|
close(demux.out);
|
2012-10-26 23:53:53 +08:00
|
|
|
if (finish_async(&demux)) {
|
|
|
|
|
error("error in sideband demultiplexer");
|
|
|
|
|
ret = -1;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (ret < 0)
|
|
|
|
|
return ret;
|
|
|
|
|
|
|
|
|
|
if (args->porcelain)
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
|
|
for (ref = remote_refs; ref; ref = ref->next) {
|
|
|
|
|
switch (ref->status) {
|
|
|
|
|
case REF_STATUS_NONE:
|
|
|
|
|
case REF_STATUS_UPTODATE:
|
|
|
|
|
case REF_STATUS_OK:
|
|
|
|
|
break;
|
|
|
|
|
default:
|
|
|
|
|
return -1;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
