kernel/git - git - PowerEL Git System

Author	SHA1	Message	Date
Michael J Gruber	b9459019bb	push: heed user.signingkey for signed pushes push --signed promises to take user.signingkey as the signing key but fails to read the config. Make it do so. Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	10 years ago
Junio C Hamano	b89363e4a5	signed push: fortify against replay attacks 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>	11 years ago
Junio C Hamano	20a7558f31	send-pack: send feature request on push-cert packet We would want to update the interim protocol so that we do not send the usual update commands when the push certificate feature is in use, as the same information is in the certificate. Once that happens, the push-cert packet may become the only protocol command, but then there is no packet to put the feature request behind, like we always did. As we have prepared the receiving end that understands the push-cert feature to accept the feature request on the first protocol packet (other than "shallow ", which was an unfortunate historical mistake that has to come before everything else), we can give the feature request on the push-cert packet instead of the first update protocol packet, in preparation for the next step to actually update to the final protocol. Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Junio C Hamano	d05b9618ce	receive-pack: GPG-validate push certificates Reusing the GPG signature check helpers we already have, verify the signature in receive-pack and give the results to the hooks via GIT_PUSH_CERT_{SIGNER,KEY,STATUS} environment variables. Policy decisions, such as accepting or rejecting a good signature by a key that is not fully trusted, is left to the hook and kept outside of the core. Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Junio C Hamano	a85b377d04	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>	11 years ago