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>
Now that we have full support in Git for the authtype capability, let's
add support to the cache credential helper.
When parsing data, we always set the initial capabilities because we're
the helper, and we need both the initial and helper capabilities to be
set in order to have the helper capabilities take effect.
When emitting data, always emit the supported capability and make sure
we emit items only if we have them and they're supported by the caller.
Since we may no longer have a username or password, be sure to emit
those conditionally as well so we don't segfault on a NULL pointer.
Similarly, when comparing credentials, consider both the password and
credential fields when we're matching passwords.
Adjust the partial credential detection code so that we can store
credentials missing a username or password as long as they have an
authtype and credential.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
Now that we've implemented the state capability, let's send it along by
default when filling credentials so we can make use of it.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
Now that we have support for a wide variety of types of authentication,
it's important to indicate to other credential helpers whether they
should store credentials, since not every credential helper may
intuitively understand all possible values of the authtype field. Do so
with a boolean field called "ephemeral", to indicate whether the
credential is expected to be temporary.
For example, in HTTP Digest authentication, the Authorization header
value is based off a nonce. It isn't useful to store this value
for later use because reusing the credential long term will not result
in successful authentication due to the nonce necessarily differing.
An additional case is potentially short-lived credentials, which may
last only a few hours. It similarly wouldn't be helper for other
credential helpers to attempt to provide these much later.
We do still pass the value to "git credential store" or "git credential
erase", since it may be helpful to the original helper to know whether
the operation was successful.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We support the new credential and authtype fields, but we lack a way to
indicate to a credential helper that we'd like them to be used. Without
some sort of indication, the credential helper doesn't know if it should
try to provide us a username and password, or a pre-encoded credential.
For example, the helper might prefer a more restricted Bearer token if
pre-encoded credentials are possible, but might have to fall back to
more general username and password if not.
Let's provide a simple way to indicate whether Git (or, for that matter,
the helper) is capable of understanding the authtype and credential
fields. We send this capability when we generate a request, and the
other side may reply to indicate to us that it does, too.
For now, don't enable sending capabilities for the HTTP code. In a
future commit, we'll introduce appropriate handling for that code,
which requires more in-depth work.
The logic for determining whether a capability is supported may seem
complex, but it is not. At each stage, we emit the capability to the
following stage if all preceding stages have declared it. Thus, if the
caller to git credential fill didn't declare it, then we won't send it
to the helper, and if fill's caller did send but the helper doesn't
understand it, then we won't send it on in the response. If we're an
internal user, then we know about all capabilities and will request
them.
For "git credential approve" and "git credential reject", we set the
helper capability before calling the helper, since we assume that the
input we're getting from the external program comes from a previous call
to "git credential fill", and thus we'll invoke send a capability to the
helper if and only if we got one from the standard input, which is the
correct behavior.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
At the moment, our credential code wants to find a username and password
for access, which, for HTTP, it will pass to libcurl to encode and
process. However, many users want to use authentication schemes that
libcurl doesn't support, such as Bearer authentication. In these
schemes, the secret is not a username and password pair, but some sort
of token that meets the production for authentication data in the RFC.
In fact, in general, it's useful to allow our credential helper to have
knowledge about what specifically to put in the protocol header. Thus,
add a field, credential, which contains data that's preencoded to be
suitable for the protocol in question. If we have such data, we need
neither a username nor a password, so make that adjustment as well.
It is in theory possible to reuse the password field for this. However,
if we do so, we must know whether the credential helper supports our new
scheme before sending it data, which necessitates some sort of
capability inquiry, because otherwise an uninformed credential helper
would store our preencoded data as a password, which would fail the next
time we attempted to connect to the remote server. This design is
substantially simpler, and we can hint to the credential helper that we
support this approach with a simple new field instead of needing to
query it first.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When Git makes an HTTP request, it can negotiate the type of
authentication to use with the server provided the authentication scheme
is one of a few well-known types (Basic, Digest, NTLM, or Negotiate).
However, some servers wish to use other types of authentication, such as
the Bearer type from OAuth2. Since libcurl doesn't natively support
this type, it isn't possible to use it, and the user is forced to
specify the Authorization header using the http.extraheader setting.
However, storing a plaintext token in the repository configuration is
not very secure, especially if a repository can be shared by multiple
parties. We already have support for many types of secure credential
storage by using credential helpers, so let's teach credential helpers
how to produce credentials for an arbitrary scheme.
If the credential helper specifies an authtype field, then it specifies
an authentication scheme (e.g., Bearer) and the password field specifies
the raw authentication token, with any encoding already specified. We
reuse the password field for this because some credential helpers store
the metadata without encryption even though the password is encrypted,
and we'd like to avoid insecure storage if an older version of the
credential helper gets ahold of the data.
The username is not used in this case, but it is still preserved for the
purpose of finding the right credential if the user has multiple
accounts.
If the authtype field is not specified, then the password behaves as
normal and it is passed along with the username to libcurl.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our select_all() callback does not need to actually look at its
parameters, since the point is to match everything. But we need to mark
its parameters to satisfy -Wunused-parameter.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a new "const struct config_context *ctx" arg to config_fn_t to hold
additional information about the config iteration operation.
config_context has a "struct key_value_info kvi" member that holds
metadata about the config source being read (e.g. what kind of config
source it is, the filename, etc). In this series, we're only interested
in .kvi, so we could have just used "struct key_value_info" as an arg,
but config_context makes it possible to add/adjust members in the future
without changing the config_fn_t signature. We could also consider other
ways of organizing the args (e.g. moving the config name and value into
config_context or key_value_info), but in my experiments, the
incremental benefit doesn't justify the added complexity (e.g. a
config_fn_t will sometimes invoke another config_fn_t but with a
different config value).
In subsequent commits, the .kvi member will replace the global "struct
config_reader" in config.c, making config iteration a global-free
operation. It requires much more work for the machinery to provide
meaningful values of .kvi, so for now, merely change the signature and
call sites, pass NULL as a placeholder value, and don't rely on the arg
in any meaningful way.
Most of the changes are performed by
contrib/coccinelle/config_fn_ctx.pending.cocci, which, for every
config_fn_t:
- Modifies the signature to accept "const struct config_context *ctx"
- Passes "ctx" to any inner config_fn_t, if needed
- Adds UNUSED attributes to "ctx", if needed
Most config_fn_t instances are easily identified by seeing if they are
called by the various config functions. Most of the remaining ones are
manually named in the .cocci patch. Manual cleanups are still needed,
but the majority of it is trivial; it's either adjusting config_fn_t
that the .cocci patch didn't catch, or adding forward declarations of
"struct config_context ctx" to make the signatures make sense.
The non-trivial changes are in cases where we are invoking a config_fn_t
outside of config machinery, and we now need to decide what value of
"ctx" to pass. These cases are:
- trace2/tr2_cfg.c:tr2_cfg_set_fl()
This is indirectly called by git_config_set() so that the trace2
machinery can notice the new config values and update its settings
using the tr2 config parsing function, i.e. tr2_cfg_cb().
- builtin/checkout.c:checkout_main()
This calls git_xmerge_config() as a shorthand for parsing a CLI arg.
This might be worth refactoring away in the future, since
git_xmerge_config() can call git_default_config(), which can do much
more than just parsing.
Handle them by creating a KVI_INIT macro that initializes "struct
key_value_info" to a reasonable default, and use that to construct the
"ctx" arg.
Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Test that credential helpers do not erase a password distinct from the
input. Such calls can happen when multiple credential helpers are
configured.
Fixes for credential-cache and credential-store.
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The implementation of credential helpers used fgets() over fixed
size buffers to read protocol messages, causing the remainder of
the folded long line to trigger unexpected behaviour, which has
been corrected.
* tb/credential-long-lines:
contrib/credential: embiggen fixed-size buffer in wincred
contrib/credential: avoid fixed-size buffer in libsecret
contrib/credential: .gitignore libsecret build artifacts
contrib/credential: remove 'gnome-keyring' credential helper
contrib/credential: avoid fixed-size buffer in osxkeychain
t/lib-credential.sh: ensure credential helpers handle long headers
credential.c: store "wwwauth[]" values in `credential_read()`
Teach git-credential to read "wwwauth[]" value(s) when parsing the
output of a credential helper.
These extra headers are not needed for Git's own HTTP support to use the
feature internally, but the feature would not be available for a
scripted caller (say, git-remote-mediawiki providing the header in the
same way).
As a bonus, this also makes it easier to use wwwauth[] in synthetic
credential inputs in our test suite.
Co-authored-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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] 66b94e489a/src/shared/GitLab/GitLabHostProvider.cs (L207)
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is another step towards letting us remove the include of cache.h in
strbuf.c. It does mean that we also need to add includes of abspath.h
in a number of C files.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Dozens of files made use of gettext functions, without explicitly
including gettext.h. This made it more difficult to find which files
could remove a dependence on cache.h. Make C files explicitly include
gettext.h if they are using it.
However, while compat/fsmonitor/fsm-ipc-darwin.c should also gain an
include of gettext.h, it was left out to avoid conflicting with an
in-flight topic.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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
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>
Read and store the HTTP WWW-Authenticate response headers made for
a particular request.
This will allow us to pass important authentication challenge
information to credential helpers or others that would otherwise have
been lost.
libcurl only provides us with the ability to read all headers recieved
for a particular request, including any intermediate redirect requests
or proxies. The lines returned by libcurl include HTTP status lines
delinating any intermediate requests such as "HTTP/1.1 200". We use
these lines to reset the strvec of WWW-Authenticate header values as
we encounter them in order to only capture the final response headers.
The collection of all header values matching the WWW-Authenticate
header is complicated by the fact that it is legal for header fields to
be continued over multiple lines, but libcurl only gives us each
physical line a time, not each logical header. This line folding feature
is deprecated in RFC 7230 [1] but older servers may still emit them, so
we need to handle them.
In the future [2] we may be able to leverage functions to read headers
from libcurl itself, but as of today we must do this ourselves.
[1] https://www.rfc-editor.org/rfc/rfc7230#section-3.2
[2] https://daniel.haxx.se/blog/2022/03/22/a-headers-api-for-libcurl/
Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
Plug a memory leak in credential_apply_config() by adding and using a
new urlmatch_config_release() function. This just does a
string_list_clear() on the "vars" member.
This finished up work on normalizing the init/free pattern in this
API, started in 73ee449bbf (urlmatch.[ch]: add and use
URLMATCH_CONFIG_INIT, 2021-10-01).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the initialization pattern of "struct urlmatch_config" to use
an *_INIT macro and designated initializers. Right now there's no
other "struct" member of "struct urlmatch_config" which would require
its own *_INIT, but it's good practice not to assume that. Let's also
change this to a designated initializer while we're at it.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the common patter in the codebase of duplicating the
initialization logic between an *_INIT macro and a
corresponding *_init() function to use the macro as the canonical
source of truth.
Now we no longer need to keep the function up-to-date with the macro
version. This implements a suggestion by Jeff King who found that
under -O2 [1] modern compilers will init new version in place without
the extra copy[1]. The performance of a single *_init() won't matter
in most cases, but even if it does we're going to be producing
efficient machine code to perform these operations.
1. https://lore.kernel.org/git/YNyrDxUO1PlGJvCn@coredump.intra.peff.net/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This fix makes using Git credentials more friendly to Windows users: it
allows a credential helper to communicate using CR/LF line endings ("DOS
line endings" commonly found on Windows) instead of LF-only line endings
("Unix line endings").
Note that this changes the behavior a bit: if a credential helper
produces, say, a password with a trailing Carriage Return character,
that will now be culled even when the rest of the lines end only in Line
Feed characters, indicating that the Carriage Return was not meant to be
part of the line ending.
In practice, it seems _very_ unlikely that something like this happens.
Passwords usually need to consist of non-control characters, URLs need
to have special characters URL-encoded, and user names, well, are names.
However, it _does_ help on Windows, where CR/LF line endings are common:
as unrecognized commands are simply ignored by the credential machinery,
even a command like `quit\r` (which is clearly intended to abort) would
simply be ignored (silently) by Git.
So let's change the credential machinery to accept both CR/LF and LF
line endings.
While we do this for the credential helper protocol, we do _not_ adjust
`git credential-cache--daemon` (which won't work on Windows, anyway,
because it requires Unix sockets) nor `git credential-store` (which
writes the file `~/.git-credentials` which we consider an implementation
detail that should be opaque to the user, read: we do expect users _not_
to edit this file manually).
Signed-off-by: Nikita Leonov <nykyta.leonov@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The child_process structure has an embedded strvec for formulating
the command line argument list these days, but code that predates
the wide use of it prepared a separate char *argv[] array and
manually set the child_process.argv pointer point at it.
Teach these old-style code to lose the separate argv[] array.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The same as js/partial-urlmatch-2.17, built on more recent codebase
to avoid unnecessary merge conflicts.
* js/partial-urlmatch:
credential: handle `credential.<partial-URL>.<key>` again
credential: optionally allow partial URLs in credential_from_url_gently()
Recent updates broke parsing of "credential.<url>.<key>" where
<url> is not a full URL (e.g. [credential "https://"] helper = ...)
stopped working, which has been corrected.
* js/partial-urlmatch-2.17:
credential: handle `credential.<partial-URL>.<key>` again
credential: optionally allow partial URLs in credential_from_url_gently()
credential: fix grammar
Update the parser used for credential.<URL>.<variable>
configuration, to handle <URL>s with '/' in them correctly.
* bc/wildcard-credential:
credential: fix matching URLs with multiple levels in path
In the patches for CVE-2020-11008, the ability to specify credential
settings in the config for partial URLs got lost. For example, it used
to be possible to specify a credential helper for a specific protocol:
[credential "https://"]
helper = my-https-helper
Likewise, it used to be possible to configure settings for a specific
host, e.g.:
[credential "dev.azure.com"]
useHTTPPath = true
Let's reinstate this behavior.
While at it, increase the test coverage to document and verify the
behavior with a couple other categories of partial URLs.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
46fd7b3900 ("credential: allow wildcard patterns when matching config",
2020-02-20) introduced support for matching credential helpers using
urlmatch. In doing so, it introduced code to percent-encode the paths
we get from the credential helper so that they could be effectively
matched by the urlmatch code.
Unfortunately, that code had a bug: it percent-encoded the slashes in
the path, resulting in any URL path that contained multiple levels
(i.e., a directory component) not matching.
We are currently the only caller of the percent-encoding code and could
simply change it not to encode slashes. However, we still want to
encode slashes in the username component, so we need to have both
behaviors available.
So instead, let's add a flag to control encoding slashes, which is the
behavior we want here, and use it when calling the code in this case.
Add a test for credential helper URLs using multiple slashes in the
path, which our test suite previously lacked, as well as one ensuring
that we handle usernames with slashes gracefully. Since we're testing
other percent-encoding handling, let's add one for non-ASCII UTF-8
characters as well.
Reported-by: Ilya Tretyakov <it@it3xl.ru>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the patches for CVE-2020-11008, the ability to specify credential
settings in the config for partial URLs got lost. For example, it used
to be possible to specify a credential helper for a specific protocol:
[credential "https://"]
helper = my-https-helper
Likewise, it used to be possible to configure settings for a specific
host, e.g.:
[credential "dev.azure.com"]
useHTTPPath = true
Let's reinstate this behavior.
While at it, increase the test coverage to document and verify the
behavior with a couple other categories of partial URLs.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Prior to the fixes for CVE-2020-11008, we were _very_ lenient in what we
required from a URL in order to parse it into a `struct credential`.
That led to serious vulnerabilities.
There was one call site, though, that really needed that leniency: when
parsing config settings a la `credential.dev.azure.com.useHTTPPath`.
Settings like this might be desired when users want to use, say, a given
user name on a given host, regardless of the protocol to be used.
In preparation for fixing that bug, let's refactor the code to
optionally allow for partial URLs. For the moment, this functionality is
only exposed via the now-renamed function `credential_from_url_1()`, but
it is not used. The intention is to make it easier to verify that this
commit does not change the existing behavior unless explicitly allowing
for partial URLs.
Please note that this patch does more than just reinstating a way to
imitate the behavior before those CVE-2020-11008 fixes: Before that, we
would simply ignore URLs without a protocol. In other words,
misleadingly, the following setting would be applied to _all_ URLs:
[credential "example.com"]
username = that-me
The obvious intention is to match the host name only. With this patch,
we allow precisely that: when parsing the URL with non-zero
`allow_partial_url`, we do not simply return success if there was no
protocol, but we simply leave the protocol unset and continue parsing
the URL.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Prior to the fixes for CVE-2020-11008, we were _very_ lenient in what we
required from a URL in order to parse it into a `struct credential`.
That led to serious vulnerabilities.
There was one call site, though, that really needed that leniency: when
parsing config settings a la `credential.dev.azure.com.useHTTPPath`.
Settings like this might be desired when users want to use, say, a given
user name on a given host, regardless of the protocol to be used.
In preparation for fixing that bug, let's refactor the code to
optionally allow for partial URLs. For the moment, this functionality is
only exposed via the now-renamed function `credential_from_url_1()`, but
it is not used. The intention is to make it easier to verify that this
commit does not change the existing behavior unless explicitly allowing
for partial URLs.
Please note that this patch does more than just reinstating a way to
imitate the behavior before those CVE-2020-11008 fixes: Before that, we
would simply ignore URLs without a protocol. In other words,
misleadingly, the following setting would be applied to _all_ URLs:
[credential "example.com"]
username = that-me
The obvious intention is to match the host name only. With this patch,
we allow precisely that: when parsing the URL with non-zero
`allow_partial_url`, we do not simply return success if there was no
protocol, but we simply leave the protocol unset and continue parsing
the URL.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Parsing of URL for the credential helper has been corrected.
* jk/credential-parsing-end-of-host-in-URL:
credential: treat "?" and "#" in URLs as end of host
Until "credential: refuse to operate when missing host or protocol",
Git's credential handling code interpreted URLs with empty scheme to
mean "give me credentials matching this host for any protocol".
Luckily libcurl does not recognize such URLs (it tries to look for a
protocol named "" and fails). Just in case that changes, let's reject
them within Git as well. This way, credential_from_url is guaranteed to
always produce a "struct credential" with protocol and host set.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
libcurl permits making requests without a URL scheme specified. In
this case, it guesses the URL from the hostname, so I can run
git ls-remote http::ftp.example.com/path/to/repo
and it would make an FTP request.
Any user intentionally using such a URL is likely to have made a typo.
Unfortunately, credential_from_url is not able to determine the host and
protocol in order to determine appropriate credentials to send, and
until "credential: refuse to operate when missing host or protocol",
this resulted in another host's credentials being leaked to the named
host.
Teach credential_from_url_gently to consider such a URL to be invalid
so that fsck can detect and block gitmodules files with such URLs,
allowing server operators to avoid serving them to downstream users
running older versions of Git.
This also means that when such URLs are passed on the command line, Git
will print a clearer error so affected users can switch to the simpler
URL that explicitly specifies the host and protocol they intend.
One subtlety: .gitmodules files can contain relative URLs, representing
a URL relative to the URL they were cloned from. The relative URL
resolver used for .gitmodules can follow ".." components out of the path
part and past the host part of a URL, meaning that such a relative URL
can be used to traverse from a https://foo.example.com/innocent
superproject to a https::attacker.example.com/exploit submodule.
Fortunately a leading ':' in the first path component after a series of
leading './' and '../' components is unlikely to show up in other
contexts, so we can catch this by detecting that pattern.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
When we try to initialize credential loading by URL and find that the
URL is invalid, we set all fields to NULL in order to avoid acting on
malicious input. Later when we request credentials, we diagonse the
erroneous input:
fatal: refusing to work with credential missing host field
This is problematic in two ways:
- The message doesn't tell the user *why* we are missing the host
field, so they can't tell from this message alone how to recover.
There can be intervening messages after the original warning of
bad input, so the user may not have the context to put two and two
together.
- The error only occurs when we actually need to get a credential. If
the URL permits anonymous access, the only encouragement the user gets
to correct their bogus URL is a quiet warning.
This is inconsistent with the check we perform in fsck, where any use
of such a URL as a submodule is an error.
When we see such a bogus URL, let's not try to be nice and continue
without helpers. Instead, die() immediately. This is simpler and
obviously safe. And there's very little chance of disrupting a normal
workflow.
It's _possible_ that somebody has a legitimate URL with a raw newline in
it. It already wouldn't work with credential helpers, so this patch
steps that up from an inconvenience to "we will refuse to work with it
at all". If such a case does exist, we should figure out a way to work
with it (especially if the newline is only in the path component, which
we normally don't even pass to helpers). But until we see a real report,
we're better off being defensive.
Reported-by: Carlo Arenas <carenas@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
The credential helper protocol was designed to be very flexible: the
fields it takes as input are treated as a pattern, and any missing
fields are taken as wildcards. This allows unusual things like:
echo protocol=https | git credential reject
to delete all stored https credentials (assuming the helpers themselves
treat the input that way). But when helpers are invoked automatically by
Git, this flexibility works against us. If for whatever reason we don't
have a "host" field, then we'd match _any_ host. When you're filling a
credential to send to a remote server, this is almost certainly not what
you want.
Prevent this at the layer that writes to the credential helper. Add a
check to the credential API that the host and protocol are always passed
in, and add an assertion to the credential_write function that speaks
credential helper protocol to be doubly sure.
There are a few ways this can be triggered in practice:
- the "git credential" command passes along arbitrary credential
parameters it reads from stdin.
- until the previous patch, when the host field of a URL is empty, we
would leave it unset (rather than setting it to the empty string)
- a URL like "example.com/foo.git" is treated by curl as if "http://"
was present, but our parser sees it as a non-URL and leaves all
fields unset
- the recent fix for URLs with embedded newlines blanks the URL but
otherwise continues. Rather than having the desired effect of
looking up no credential at all, many helpers will return _any_
credential
Our earlier test for an embedded newline didn't catch this because it
only checked that the credential was cleared, but didn't configure an
actual helper. Configuring the "verbatim" helper in the test would show
that it is invoked (it's obviously a silly helper which doesn't look at
its input, but the point is that it shouldn't be run at all). Since
we're switching this case to die(), we don't need to bother with a
helper. We can see the new behavior just by checking that the operation
fails.
We'll add new tests covering partial input as well (these can be
triggered through various means with url-parsing, but it's simpler to
just check them directly, as we know we are covered even if the url
parser changes behavior in the future).
[jn: changed to die() instead of logging and showing a manual
username/password prompt]
Reported-by: Carlo Arenas <carenas@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
We may feed a URL like "cert:///path/to/cert.pem" into the credential
machinery to get the key for a client-side certificate. That
credential has no hostname field, which is about to be disallowed (to
avoid confusion with protocols where a helper _would_ expect a
hostname).
This means as of the next patch, credential helpers won't work for
unlocking certs. Let's fix that by doing two things:
- when we parse a url with an empty host, set the host field to the
empty string (asking only to match stored entries with an empty
host) rather than NULL (asking to match _any_ host).
- when we build a cert:// credential by hand, similarly assign an
empty string
It's the latter that is more likely to impact real users in practice,
since it's what's used for http connections. But we don't have good
infrastructure to test it.
The url-parsing version will help anybody using git-credential in a
script, and is easy to test.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
It's unusual to see:
https://example.com?query-parameters
without an intervening slash, like:
https://example.com/some-path?query-parameters
or even:
https://example.com/?query-parameters
but it is a valid end to the hostname (actually "authority component")
according to RFC 3986. Likewise for "#".
And curl will parse the URL according to the standard, meaning it will
contact example.com, but our credential code would ask about a bogus
hostname with a "?" in it. Let's make sure we follow the standard, and
more importantly ask about the same hosts that curl will be talking to.
It would be nice if we could just ask curl to parse the URL for us. But
it didn't grow a URL-parsing API until 7.62, so we'd be stuck with
fallback code either way. Plus we'd need this code in the main Git
binary, where we've tried to avoid having a link dependency on libcurl.
But let's at least fix our parser. Moving to curl's parser would prevent
other potential discrepancies, but this gives us immediate relief for
the known problem, and would help our fallback code if we eventually use
curl.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The credential protocol can't represent newlines in values, but URLs can
embed percent-encoded newlines in various components. A previous commit
taught the low-level writing routines to die() when encountering this,
but we can be a little friendlier to the user by detecting them earlier
and handling them gracefully.
This patch teaches credential_from_url() to notice such components,
issue a warning, and blank the credential (which will generally result
in prompting the user for a username and password). We blank the whole
credential in this case. Another option would be to blank only the
invalid component. However, we're probably better off not feeding a
partially-parsed URL result to a credential helper. We don't know how a
given helper would handle it, so we're better off to err on the side of
matching nothing rather than something unexpected.
The die() call in credential_write() is _probably_ impossible to reach
after this patch. Values should end up in credential structs only by URL
parsing (which is covered here), or by reading credential protocol input
(which by definition cannot read a newline into a value). But we should
definitely keep the low-level check, as it's our final and most accurate
line of defense against protocol injection attacks. Arguably it could
become a BUG(), but it probably doesn't matter much either way.
Note that the public interface of credential_from_url() grows a little
more than we need here. We'll use the extra flexibility in a future
patch to help fsck catch these cases.
