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* credential: add method for querying capabilitiesbrian m. carlson2024-04-171-1/+27
| | | | | | | | | | | | | | | | | | | | | Right now, there's no specific way to determine whether a credential helper or git credential itself supports a given set of capabilities. It would be helpful to have such a way, so let's let credential helpers and git credential take an argument, "capability", which has it list the capabilities and a version number on standard output. Specifically choose a format that is slightly different from regular credential output and assume that no capabilities are supported if a non-zero exit status occurs or the data deviates from the format. It is common for users to write small shell scripts as the argument to credential.helper, which will almost never be designed to emit capabilities. We want callers to gracefully handle this case by assuming that they are not capable of extended support because that is almost certainly the case, and specifying the error behavior up front does this and preserves backwards compatibility in a graceful way. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: add support for multistage credential roundsbrian m. carlson2024-04-171-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Over HTTP, NTLM and Kerberos require two rounds of authentication on the client side. It's possible that there are custom authentication schemes that also implement this same approach. Since these are tricky schemes to implement and the HTTP library in use may not always handle them gracefully on all systems, it would be helpful to allow the credential helper to implement them instead for increased portability and robustness. To allow this to happen, add a boolean flag, continue, that indicates that instead of failing when we get a 401, we should retry another round of authentication. However, this necessitates some changes in our current credential code so that we can make this work. Keep the state[] headers between iterations, but only use them to send to the helper and only consider the new ones we read from the credential helper to be valid on subsequent iterations. That avoids us passing stale data when we finally approve or reject the credential. Similarly, clear the multistage and wwwauth[] values appropriately so that we don't pass stale data or think we're trying a multiround response when we're not. Remove the credential values so that we can actually fill a second time with new responses. Limit the number of iterations of reauthentication we do to 3. This means that if there's a problem, we'll terminate with an error message instead of retrying indefinitely and not informing the user (and possibly conducting a DoS on the server). In our tests, handle creating multiple response output files from our helper so we can verify that each of the messages sent is correct. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* docs: set a limit on credential line lengthbrian m. carlson2024-04-171-1/+3
| | | | | | | | | | | | | | | | | We recently introduced a way for credential helpers to add arbitrary state as part of the protocol. Set some limits on line length to avoid helpers passing extremely large amounts of data. While Git doesn't have a fixed parsing length, there are other tools which support this protocol and it's kind to allow them to use a reasonable fixed-size buffer for parsing. In addition, we would like to be moderate in our memory usage and imposing reasonable limits is helpful for that purpose. In the event a credential helper is incapable of storing its serialized state in 64 KiB, it can feel free to serialize it on disk and store a reference instead. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: add an argument to keep statebrian m. carlson2024-04-171-9/+19
| | | | | | | | | | | | | | | | | | | | | | | | Until now, our credential code has mostly deal with usernames and passwords and we've let libcurl deal with the variant of authentication to be used. However, now that we have the credential value, the credential helper can take control of the authentication, so the value provided might be something that's generated, such as a Digest hash value. In such a case, it would be helpful for a credential helper that gets an erase or store command to be able to keep track of an identifier for the original secret that went into the computation. Furthermore, some types of authentication, such as NTLM and Kerberos, actually need two round trips to authenticate, which will require that the credential helper keep some state. In order to allow for these use cases and others, allow storing state in a field called "state[]". This value is passed back to the credential helper that created it, which avoids confusion caused by parsing values from different helpers. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* docs: indicate new credential protocol fieldsbrian m. carlson2024-04-171-1/+48
| | | | | | | | | | | | | | | | Now that we have new fields (authtype and credential), let's document them for users and credential helper implementers. Indicate specifically what common values of authtype are and what values are allowed. Note that, while common, digest and NTLM authentication are insecure because they require unsalted, uniterated password hashes to be stored. Tell users that they can continue to use a username and password even if the new capability is supported. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* documentation: wording improvementsElijah Newren2023-10-091-1/+1
| | | | | | | Diff best viewed with --color-diff. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: erase all matching credentialsM Hickford2023-06-151-1/+1
| | | | | | | | | | | | | | | | | | | `credential reject` sends the erase action to each helper, but the exact behaviour of erase isn't specified in documentation or tests. Some helpers (such as credential-store and credential-libsecret) delete all matching credentials, others (such as credential-cache) delete at most one matching credential. Test that helpers erase all matching credentials. This behaviour is easiest to reason about. Users expect that `echo "url=https://example.com" | git credential reject` or `echo "url=https://example.com\nusername=tim" | git credential reject` erase all matching credentials. Fix credential-cache. Signed-off-by: M Hickford <mirth.hickford@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Merge branch 'mh/credential-oauth-refresh-token'Junio C Hamano2023-05-101-0/+6
|\ | | | | | | | | | | | | The credential subsystem learns to help OAuth framework. * mh/credential-oauth-refresh-token: credential: new attribute oauth_refresh_token
| * credential: new attribute oauth_refresh_tokenM Hickford2023-04-211-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Git authentication with OAuth access token is supported by every popular Git host including GitHub, GitLab and BitBucket [1][2][3]. Credential helpers Git Credential Manager (GCM) and git-credential-oauth generate OAuth credentials [4][5]. Following RFC 6749, the application prints a link for the user to authorize access in browser. A loopback redirect communicates the response including access token to the application. For security, RFC 6749 recommends that OAuth response also includes expiry date and refresh token [6]. After expiry, applications can use the refresh token to generate a new access token without user reauthorization in browser. GitLab and BitBucket set the expiry at two hours [2][3]. (GitHub doesn't populate expiry or refresh token.) However the Git credential protocol has no attribute to store the OAuth refresh token (unrecognised attributes are silently discarded). This means that the user has to regularly reauthorize the helper in browser. On a browserless system, this is particularly intrusive, requiring a second device. Introduce a new attribute oauth_refresh_token. This is especially useful when a storage helper and a read-only OAuth helper are configured together. Recall that `credential fill` calls each helper until it has a non-expired password. ``` [credential] helper = storage # eg. cache or osxkeychain helper = oauth ``` The OAuth helper can use the stored refresh token forwarded by `credential fill` to generate a fresh access token without opening the browser. See https://github.com/hickford/git-credential-oauth/pull/3/files for an implementation tested with this patch. Add support for the new attribute to credential-cache. Eventually, I hope to see support in other popular storage helpers. Alternatives considered: ask helpers to store all unrecognised attributes. This seems excessively complex for no obvious gain. Helpers would also need extra information to distinguish between confidential and non-confidential attributes. Workarounds: GCM abuses the helper get/store/erase contract to store the refresh token during credential *get* as the password for a fictitious host [7] (I wrote this hack). This workaround is only feasible for a monolithic helper with its own storage. [1] https://github.blog/2012-09-21-easier-builds-and-deployments-using-git-over-https-and-oauth/ [2] https://docs.gitlab.com/ee/api/oauth2.html#access-git-over-https-with-access-token [3] https://support.atlassian.com/bitbucket-cloud/docs/use-oauth-on-bitbucket-cloud/#Cloning-a-repository-with-an-access-token [4] https://github.com/GitCredentialManager/git-credential-manager [5] https://github.com/hickford/git-credential-oauth [6] https://datatracker.ietf.org/doc/html/rfc6749#section-5.1 [7] https://github.com/GitCredentialManager/git-credential-manager/blob/66b94e489ad8cc1982836355493e369770b30211/src/shared/GitLab/GitLabHostProvider.cs#L207 Signed-off-by: M Hickford <mirth.hickford@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'mc/credential-helper-www-authenticate'Junio C Hamano2023-03-171-1/+18
|\ \ | |/ |/| | | | | | | | | | | | | | | Allow information carried on the WWW-AUthenticate header to be passed to the credential helpers. * mc/credential-helper-www-authenticate: credential: add WWW-Authenticate header to cred requests http: read HTTP WWW-Authenticate response headers t5563: add tests for basic and anoymous HTTP access
| * credential: add WWW-Authenticate header to cred requestsMatthew John Cheetham2023-02-271-1/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the value of the WWW-Authenticate response header to credential requests. Credential helpers that understand and support HTTP authentication and authorization can use this standard header (RFC 2616 Section 14.47 [1]) to generate valid credentials. WWW-Authenticate headers can contain information pertaining to the authority, authentication mechanism, or extra parameters/scopes that are required. The current I/O format for credential helpers only allows for unique names for properties/attributes, so in order to transmit multiple header values (with a specific order) we introduce a new convention whereby a C-style array syntax is used in the property name to denote multiple ordered values for the same property. In this case we send multiple `wwwauth[]` properties where the order that the repeated attributes appear in the conversation reflects the order that the WWW-Authenticate headers appeared in the HTTP response. Add a set of tests to exercise the HTTP authentication header parsing and the interop with credential helpers. Credential helpers will receive WWW-Authenticate information in credential requests. [1] https://datatracker.ietf.org/doc/html/rfc2616#section-14.47 Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | credential: new attribute password_expiry_utcM Hickford2023-02-231-0/+6
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some passwords have an expiry date known at generation. This may be years away for a personal access token or hours for an OAuth access token. When multiple credential helpers are configured, `credential fill` tries each helper in turn until it has a username and password, returning early. If Git authentication succeeds, `credential approve` stores the successful credential in all helpers. If authentication fails, `credential reject` erases matching credentials in all helpers. Helpers implement corresponding operations: get, store, erase. The credential protocol has no expiry attribute, so helpers cannot store expiry information. Even if a helper returned an improvised expiry attribute, git credential discards unrecognised attributes between operations and between helpers. This is a particular issue when a storage helper and a credential-generating helper are configured together: [credential] helper = storage # eg. cache or osxkeychain helper = generate # eg. oauth `credential approve` stores the generated credential in both helpers without expiry information. Later `credential fill` may return an expired credential from storage. There is no workaround, no matter how clever the second helper. The user sees authentication fail (a retry will succeed). Introduce a password expiry attribute. In `credential fill`, ignore expired passwords and continue to query subsequent helpers. In the example above, `credential fill` ignores the expired password and a fresh credential is generated. If authentication succeeds, `credential approve` replaces the expired password in storage. If authentication fails, the expired credential is erased by `credential reject`. It is unnecessary but harmless for storage helpers to self prune expired credentials. Add support for the new attribute to credential-cache. Eventually, I hope to see support in other popular storage helpers. Example usage in a credential-generating helper https://github.com/hickford/git-credential-oauth/pull/16 Signed-off-by: M Hickford <mirth.hickford@gmail.com> Reviewed-by: Calvin Wan <calvinwan@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* docs: clarify that credential discards unrecognised attributesM Hickford2022-11-131-0/+2
| | | | | | | It was previously unclear how unrecognised attributes are handled. Signed-off-by: M Hickford <mirth.hickford@gmail.com> Signed-off-by: Taylor Blau <me@ttaylorr.com>
* doc: fix git credential synopsisJean-Noël Avila2021-10-281-1/+1
| | | | | | | The subcommand of git credential is not optional. Signed-off-by: Jean-Noël Avila <jn.avila@free.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* doc lint: lint and fix missing "GIT" end sectionsÆvar Arnfjörð Bjarmason2021-04-111-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Lint for and fix the three manual pages that were missing the standard "Part of the linkgit:git[1] suite" end section. We only do this for the man[157] section documents (we don't have anything outside those sections), not files to be included, howto *.txt files etc. We could also add this to the existing (and then renamed) lint-gitlink.perl, but I'm not doing that here. Obviously all of that fits in one script, but I think for something like this that's a one-off script with global variables it's much harder to follow when a large part of your script is some if/else or keeping/resetting of state simply to work around the script doing two things instead of one. Especially because in this case this script wants to process the file as one big string, but lint-gitlink.perl wants to look at it one line at a time. We could also consolidate this whole thing and t/check-non-portable-shell.pl, but that one likes to join lines as part of its shell parsing. So let's just add another script, whole scaffolding is basically: use strict; use warnings; sub report { ... } my $code = 0; while (<>) { ... } exit $code; We'd spend more lines effort trying to consolidate them than just copying that around. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* git-credential.txt: use list continuationMartin Ågren2020-05-181-8/+8
| | | | | | | | | Use list continuation to avoid the second and third paragraphs rendering with a different indentation from the first one where we describe the "url" attribute. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: document protocol updatesCarlo Marcelo Arenas Belón2020-05-071-13/+21
| | | | | | | | | | | Document protocol changes after CVE-2020-11008, including the removal of references to the override of attributes which is no longer recommended after CVE-2020-5260 and that might be removed in the future. While at it do some improvements for clarity and consistency. Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: move doc to credential.hHeba Waly2019-11-181-2/+1
| | | | | | | | | | | | | | | | | Move the documentation from Documentation/technical/api-credentials.txt to credential.h as it's easier for the developers to find the usage information beside the code instead of looking for it in another doc file. Documentation/technical/api-credentials.txt is removed because the information it has is now redundant and it'll be hard to keep it up to date and synchronized with the documentation in the header file. Documentation/git-credential.txt and Documentation/gitcredentials.txt now link to credential.h instead of Documentation/technical/api-credentials.txt for details about the credetials API. Signed-off-by: Heba Waly <heba.waly@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Documentation: make AsciiDoc links always point to HTML filesSebastian Schuberth2013-09-061-1/+1
| | | | | | | | | | | | | AsciiDoc's "link" is supposed to create hyperlinks for HTML output, so prefer a "link" to point to an HTML file instead of a text file if an HTML version of the file is being generated. For RelNotes, keep pointing to text files as no equivalent HTML files are generated. If appropriate, also update the link description to not contain the linked file's extension. Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* doc: various spelling fixesStefano Lattarini2013-04-121-1/+1
| | | | | | | | Most of these were found using Lucas De Marchi's codespell tool. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Documentation: the name of the system is 'Git', not 'git'Thomas Ackermann2013-02-011-3/+3
| | | | | Signed-off-by: Thomas Ackermann <th.acker@arcor.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Documentation: list git-credential in plumbing commandsMatthieu Moy2012-08-081-1/+1
| | | | | | | | | | | | | Commit e30b2feb1b (Jun 24 2012, add 'git credential' plumbing command) forgot to add git-credential to command-list.txt, hence the command was not appearing in the documentation, making it hard for users to discover it. While we're there, capitalize the description line for git-crendential for consistency with other commands. Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* credential: convert "url" attribute into its parsed subpartsJeff King2012-07-181-0/+12
| | | | | | | | | | | | The git-credential command requires that you feed it a broken-down credential, which means that the client needs to parse a URL itself. Since we have our own URL-parsing routines, we can easily allow the caller to just give us the URL as-is, saving them some code. Signed-off-by: Jeff King <peff@peff.net> Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* docs/credential: minor clarity fixupsJeff King2012-07-181-6/+4
| | | | | | | | | | | | | The text in git-credential(1) was copied from technical/api-credentials, so it still talks about the input/output format as coming from git to the helper. Since the surrounding text already indicates that this format is used for reading and writing with git credential, we can just remove the extraneous confusing bits. Signed-off-by: Jeff King <peff@peff.net> Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* git credential fill: output the whole 'struct credential'Matthieu Moy2012-06-251-4/+12
| | | | | | | | | | | Instead of outputing only the username and password, print all the attributes, even those that already appeared in the input. This is closer to what the C API does, and allows one to take the exact output of "git credential fill" as input to "git credential approve" or "git credential reject". Signed-off-by: Junio C Hamano <gitster@pobox.com>
* add 'git credential' plumbing commandJavier Roucher Iglesias2012-06-251-0/+136
The credential API is in C, and not available to scripting languages. Expose the functionalities of the API by wrapping them into a new plumbing command "git credentials". In other words, replace the internal "test-credential" by an official Git command. Most documentation writen by: Jeff King <peff@peff.net> Signed-off-by: Pavel Volek <Pavel.Volek@ensimag.imag.fr> Signed-off-by: Kim Thuat Nguyen <Kim-Thuat.Nguyen@ensimag.imag.fr> Signed-off-by: Javier Roucher Iglesias <Javier.Roucher-Iglesias@ensimag.imag.fr> Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>