[PATCH] remote-curl: Use auth for probe_rpc() requests too

[PATCH] remote-curl: Use auth for probe_rpc() requests too

[Aaron Plattner]

If a large request requires post_rpc() to call probe_rpc(), the latter
does not use the authorization credentials used for other requests. If
this fails with an HTTP 401 error and http_auth.multistage isn't set,
then the whole request just fails.

For example, using git-credential-msal [1], the following attempt to clone a
large repository fails partway through because the initial request to download
the commit history and promisor packs succeeds, but the
subsequent request to download the blobs needed to construct the working
tree fails with a 401 error and the checkout fails.

(lines removed for brevity)

  git clone --filter=blob:none https://secure-server.example/repo
  11:03:26.855369 git.c:502               trace: built-in: git clone --filter=blob:none https://secure-server.example/repo
  Cloning into 'sw'...
  warning: templates not found in /home/aaron/share/git-core/templates
  11:03:26.857169 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
  11:03:27.012104 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
  11:03:27.049243 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
  11:03:27.049270 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
  11:03:27.053786 run-command.c:673       trace: run_command: 'git credential-msal get'
  11:03:27.952830 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
  11:03:27.952849 http.c:849              => Send header: Authorization: Bearer <redacted>
  11:03:27.995419 http.c:849              <= Recv header: HTTP/1.1 200 OK
  11:03:28.230039 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
  11:03:28.230208 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
  11:03:28.230216 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
  11:03:28.230221 http.c:849              => Send header: Authorization: Bearer <redacted>
  11:03:28.269085 http.c:849              <= Recv header: HTTP/1.1 200 OK
  11:03:28.684163 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
  11:03:28.684379 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
  11:03:28.684391 http.c:849              => Send header: Accept: application/x-git-upload-pack-result
  11:03:28.684393 http.c:849              => Send header: Authorization: Bearer <redacted>
  11:03:28.869546 run-command.c:673       trace: run_command: git index-pack --stdin --fix-thin '--keep=fetch-pack 43856 on dgx-spark' --promisor
  11:06:39.861237 run-command.c:673       trace: run_command: git -c fetch.negotiationAlgorithm=noop fetch origin --no-tags --no-write-fetch-head --recurse-submodules=no --filter=blob:none --stdin
  11:06:39.865981 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
  11:06:39.868039 run-command.c:673       trace: run_command: git-remote-https origin https://secure-server.example/repo
  11:07:30.412575 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
  11:07:30.456285 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
  11:07:30.456318 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
  11:07:30.456439 run-command.c:673       trace: run_command: 'git credential-cache get'
  11:07:30.461266 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
  11:07:30.461282 http.c:849              => Send header: Authorization: Bearer <redacted>
  11:07:30.501628 http.c:849              <= Recv header: HTTP/1.1 200 OK
  11:07:34.725262 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
  11:07:34.725279 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
  11:07:34.761407 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
  11:07:34.761443 http.c:890              == Info: Bearer authentication problem, ignoring.
  11:07:34.761453 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
  11:07:34.761509 http.c:890              == Info: The requested URL returned error: 401
  11:07:34.761530 http.c:890              == Info: closing connection #0
  11:07:34.761913 run-command.c:673       trace: run_command: 'git credential-cache erase'
  11:07:34.761927 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-cache erase' 'git credential-cache erase'
  11:07:34.768069 git.c:502               trace: built-in: git credential-cache erase
  11:07:34.768690 run-command.c:673       trace: run_command: 'git credential-msal erase'
  11:07:34.768713 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-msal erase' 'git credential-msal erase'
  11:07:34.772742 git.c:808               trace: exec: git-credential-msal erase
  11:07:34.772783 run-command.c:673       trace: run_command: git-credential-msal erase
  11:07:34.772819 run-command.c:765       trace: start_command: /usr/bin/git-credential-msal erase
  error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
  fatal: unable to write request to remote: Broken pipe
  fatal: could not fetch c4fff0229c9be06ecf576356a4d39a8a755b8d81 from promisor remote
  warning: Clone succeeded, but checkout failed.
  You can inspect what was checked out with 'git status'
  and retry with 'git restore --source=HEAD :/'

Fix the immediate problem by including the authorization headers in the
probe_rpc() request as well.

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Link: [1] https://github.com/Binary-Eater/git-credential-msal
---
If http_auth.multistage were set in this scenario, then probe_rpc() would have
returned HTTP_REAUTH and this would have probably worked by generating a new
Bearer token. And we might need to use HTTP_REAUTH to handle the case where the
token expires between the initial request and this one, but I don't think
tackling that in this patch makes sense since the original Bearer token was
still valid and git just didn't try using it. And setting multistage (the
'continue' parameter in git-credential(1)) doesn't make sense for Bearer tokens
since the token comes from an external agent.

 remote-curl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/remote-curl.c b/remote-curl.c
index 69f919454a..1d0ae72521 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -877,6 +877,8 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
 	headers = curl_slist_append(headers, rpc->hdr_content_type);
 	headers = curl_slist_append(headers, rpc->hdr_accept);
 
+	headers = http_append_auth_header(&http_auth, headers);
+
 	curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0L);
 	curl_easy_setopt(slot->curl, CURLOPT_POST, 1L);
 	curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
-- 
2.51.2

Re: [PATCH] remote-curl: Use auth for probe_rpc() requests too

[Lucas De Marchi]

On Wed, Nov 12, 2025 at 02:37:18PM -0800, Aaron Plattner wrote:
>If a large request requires post_rpc() to call probe_rpc(), the latter
>does not use the authorization credentials used for other requests. If
>this fails with an HTTP 401 error and http_auth.multistage isn't set,
>then the whole request just fails.
>
>For example, using git-credential-msal [1], the following attempt to clone a
>large repository fails partway through because the initial request to download
>the commit history and promisor packs succeeds, but the
>subsequent request to download the blobs needed to construct the working
>tree fails with a 401 error and the checkout fails.
>
>(lines removed for brevity)
>
>  git clone --filter=blob:none https://secure-server.example/repo
>  11:03:26.855369 git.c:502               trace: built-in: git clone --filter=blob:none https://secure-server.example/repo
>  Cloning into 'sw'...
>  warning: templates not found in /home/aaron/share/git-core/templates
>  11:03:26.857169 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>  11:03:27.012104 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>  11:03:27.049243 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>  11:03:27.049270 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>  11:03:27.053786 run-command.c:673       trace: run_command: 'git credential-msal get'
>  11:03:27.952830 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>  11:03:27.952849 http.c:849              => Send header: Authorization: Bearer <redacted>
>  11:03:27.995419 http.c:849              <= Recv header: HTTP/1.1 200 OK
>  11:03:28.230039 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>  11:03:28.230208 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>  11:03:28.230216 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>  11:03:28.230221 http.c:849              => Send header: Authorization: Bearer <redacted>
>  11:03:28.269085 http.c:849              <= Recv header: HTTP/1.1 200 OK
>  11:03:28.684163 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>  11:03:28.684379 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>  11:03:28.684391 http.c:849              => Send header: Accept: application/x-git-upload-pack-result
>  11:03:28.684393 http.c:849              => Send header: Authorization: Bearer <redacted>
>  11:03:28.869546 run-command.c:673       trace: run_command: git index-pack --stdin --fix-thin '--keep=fetch-pack 43856 on dgx-spark' --promisor
>  11:06:39.861237 run-command.c:673       trace: run_command: git -c fetch.negotiationAlgorithm=noop fetch origin --no-tags --no-write-fetch-head --recurse-submodules=no --filter=blob:none --stdin
>  11:06:39.865981 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>  11:06:39.868039 run-command.c:673       trace: run_command: git-remote-https origin https://secure-server.example/repo
>  11:07:30.412575 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>  11:07:30.456285 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>  11:07:30.456318 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>  11:07:30.456439 run-command.c:673       trace: run_command: 'git credential-cache get'
>  11:07:30.461266 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>  11:07:30.461282 http.c:849              => Send header: Authorization: Bearer <redacted>
>  11:07:30.501628 http.c:849              <= Recv header: HTTP/1.1 200 OK
>  11:07:34.725262 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>  11:07:34.725279 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>  11:07:34.761407 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>  11:07:34.761443 http.c:890              == Info: Bearer authentication problem, ignoring.
>  11:07:34.761453 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>  11:07:34.761509 http.c:890              == Info: The requested URL returned error: 401
>  11:07:34.761530 http.c:890              == Info: closing connection #0
>  11:07:34.761913 run-command.c:673       trace: run_command: 'git credential-cache erase'
>  11:07:34.761927 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-cache erase' 'git credential-cache erase'
>  11:07:34.768069 git.c:502               trace: built-in: git credential-cache erase
>  11:07:34.768690 run-command.c:673       trace: run_command: 'git credential-msal erase'
>  11:07:34.768713 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-msal erase' 'git credential-msal erase'
>  11:07:34.772742 git.c:808               trace: exec: git-credential-msal erase
>  11:07:34.772783 run-command.c:673       trace: run_command: git-credential-msal erase
>  11:07:34.772819 run-command.c:765       trace: start_command: /usr/bin/git-credential-msal erase
>  error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
>  fatal: unable to write request to remote: Broken pipe
>  fatal: could not fetch c4fff0229c9be06ecf576356a4d39a8a755b8d81 from promisor remote
>  warning: Clone succeeded, but checkout failed.
>  You can inspect what was checked out with 'git status'
>  and retry with 'git restore --source=HEAD :/'
>
>Fix the immediate problem by including the authorization headers in the
>probe_rpc() request as well.
>
>Signed-off-by: Aaron Plattner <aplattner@nvidia.com>

Tested-by: Lucas De Marchi <demarchi@kernel.org>

thanks,
Lucas De Marchi

Re: [PATCH] remote-curl: Use auth for probe_rpc() requests too

[Patrick Steinhardt]

Hi,

sorry for taking so long to review your patch, but I didn't really dare
to review it as I'm not that familiar with the subsystem in question.
But given that nobody else reviewed it, either, let me try my best to at
least provide _some_ helpful feedback to hopefully move this forward.

On Wed, Nov 12, 2025 at 02:37:18PM -0800, Aaron Plattner wrote:
> If a large request requires post_rpc() to call probe_rpc(), the latter
> does not use the authorization credentials used for other requests. If
> this fails with an HTTP 401 error and http_auth.multistage isn't set,
> then the whole request just fails.
> 
> For example, using git-credential-msal [1], the following attempt to clone a
> large repository fails partway through because the initial request to download
> the commit history and promisor packs succeeds, but the
> subsequent request to download the blobs needed to construct the working
> tree fails with a 401 error and the checkout fails.

Okay.

> (lines removed for brevity)
> 
>   git clone --filter=blob:none https://secure-server.example/repo
>   11:03:26.855369 git.c:502               trace: built-in: git clone --filter=blob:none https://secure-server.example/repo
>   Cloning into 'sw'...
>   warning: templates not found in /home/aaron/share/git-core/templates
>   11:03:26.857169 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>   11:03:27.012104 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>   11:03:27.049243 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>   11:03:27.049270 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>   11:03:27.053786 run-command.c:673       trace: run_command: 'git credential-msal get'
>   11:03:27.952830 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>   11:03:27.952849 http.c:849              => Send header: Authorization: Bearer <redacted>
>   11:03:27.995419 http.c:849              <= Recv header: HTTP/1.1 200 OK
>   11:03:28.230039 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>   11:03:28.230208 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>   11:03:28.230216 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>   11:03:28.230221 http.c:849              => Send header: Authorization: Bearer <redacted>
>   11:03:28.269085 http.c:849              <= Recv header: HTTP/1.1 200 OK
>   11:03:28.684163 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>   11:03:28.684379 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>   11:03:28.684391 http.c:849              => Send header: Accept: application/x-git-upload-pack-result
>   11:03:28.684393 http.c:849              => Send header: Authorization: Bearer <redacted>
>   11:03:28.869546 run-command.c:673       trace: run_command: git index-pack --stdin --fix-thin '--keep=fetch-pack 43856 on dgx-spark' --promisor
>   11:06:39.861237 run-command.c:673       trace: run_command: git -c fetch.negotiationAlgorithm=noop fetch origin --no-tags --no-write-fetch-head --recurse-submodules=no --filter=blob:none --stdin
>   11:06:39.865981 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>   11:06:39.868039 run-command.c:673       trace: run_command: git-remote-https origin https://secure-server.example/repo
>   11:07:30.412575 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>   11:07:30.456285 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>   11:07:30.456318 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>   11:07:30.456439 run-command.c:673       trace: run_command: 'git credential-cache get'
>   11:07:30.461266 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>   11:07:30.461282 http.c:849              => Send header: Authorization: Bearer <redacted>
>   11:07:30.501628 http.c:849              <= Recv header: HTTP/1.1 200 OK
>   11:07:34.725262 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>   11:07:34.725279 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>   11:07:34.761407 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized

Okay, here we see the 401 error code.

>   11:07:34.761443 http.c:890              == Info: Bearer authentication problem, ignoring.
>   11:07:34.761453 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>   11:07:34.761509 http.c:890              == Info: The requested URL returned error: 401
>   11:07:34.761530 http.c:890              == Info: closing connection #0
>   11:07:34.761913 run-command.c:673       trace: run_command: 'git credential-cache erase'
>   11:07:34.761927 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-cache erase' 'git credential-cache erase'
>   11:07:34.768069 git.c:502               trace: built-in: git credential-cache erase
>   11:07:34.768690 run-command.c:673       trace: run_command: 'git credential-msal erase'
>   11:07:34.768713 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-msal erase' 'git credential-msal erase'
>   11:07:34.772742 git.c:808               trace: exec: git-credential-msal erase
>   11:07:34.772783 run-command.c:673       trace: run_command: git-credential-msal erase
>   11:07:34.772819 run-command.c:765       trace: start_command: /usr/bin/git-credential-msal erase

And as we think that we've already set up authentication, this error
code will cause us to think that the credentials that we've got are
invalid. Consequently, we invalidate the credentials that we've stored.
Naturally, this will cause _all_ subsequent requests to fail as we're no
longer authenticated at all.

>   error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
>   fatal: unable to write request to remote: Broken pipe
>   fatal: could not fetch c4fff0229c9be06ecf576356a4d39a8a755b8d81 from promisor remote
>   warning: Clone succeeded, but checkout failed.
>   You can inspect what was checked out with 'git status'
>   and retry with 'git restore --source=HEAD :/'
> 
> Fix the immediate problem by including the authorization headers in the
> probe_rpc() request as well.
> 
> Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
> Link: [1] https://github.com/Binary-Eater/git-credential-msal
> ---
> If http_auth.multistage were set in this scenario, then probe_rpc() would have
> returned HTTP_REAUTH and this would have probably worked by generating a new
> Bearer token. And we might need to use HTTP_REAUTH to handle the case where the
> token expires between the initial request and this one, but I don't think
> tackling that in this patch makes sense since the original Bearer token was
> still valid and git just didn't try using it. And setting multistage (the
> 'continue' parameter in git-credential(1)) doesn't make sense for Bearer tokens
> since the token comes from an external agent.

This is something I was wondering about. Specifically, I saw the loop
that we had around `HTTP_REAUTH`:

		do {
			err = probe_rpc(rpc, &results);
			if (err == HTTP_REAUTH)
				credential_fill(the_repository, &http_auth, 0);
		} while (err == HTTP_REAUTH);

I then double-checked that we indeed get `HTTP_REAUTH` as an error code
on a 401, so I was wondering why this doesn't lead to an infinite loop.
I didn't connect it with the "multistage" thing though.

In any case, I think this information would be useful to have in the
commit message to help guide readers.

>  remote-curl.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/remote-curl.c b/remote-curl.c
> index 69f919454a..1d0ae72521 100644
> --- a/remote-curl.c
> +++ b/remote-curl.c
> @@ -877,6 +877,8 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
>  	headers = curl_slist_append(headers, rpc->hdr_content_type);
>  	headers = curl_slist_append(headers, rpc->hdr_accept);
>  
> +	headers = http_append_auth_header(&http_auth, headers);
> +
>  	curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0L);
>  	curl_easy_setopt(slot->curl, CURLOPT_POST, 1L);
>  	curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);

The change looks simple enough, and matches what we do in `post_rpc()`
itself.

It would be great to have a test case for this. It might be possible to
use t5563-simple-http-auth as an example, where we already know to set
up an HTTP server with authentication.

Thanks!

Patrick

Re: [PATCH] remote-curl: Use auth for probe_rpc() requests too

[Aaron Plattner]

On 1/9/26 6:51 AM, Patrick Steinhardt wrote:
> Hi,
> 
> sorry for taking so long to review your patch, but I didn't really dare
> to review it as I'm not that familiar with the subsystem in question.
> But given that nobody else reviewed it, either, let me try my best to at
> least provide _some_ helpful feedback to hopefully move this forward.

Thanks Patrick!

> On Wed, Nov 12, 2025 at 02:37:18PM -0800, Aaron Plattner wrote:
>> If a large request requires post_rpc() to call probe_rpc(), the latter
>> does not use the authorization credentials used for other requests. If
>> this fails with an HTTP 401 error and http_auth.multistage isn't set,
>> then the whole request just fails.
>>
>> For example, using git-credential-msal [1], the following attempt to clone a
>> large repository fails partway through because the initial request to download
>> the commit history and promisor packs succeeds, but the
>> subsequent request to download the blobs needed to construct the working
>> tree fails with a 401 error and the checkout fails.
> 
> Okay.
> 
>> (lines removed for brevity)
>>
>>    git clone --filter=blob:none https://secure-server.example/repo
>>    11:03:26.855369 git.c:502               trace: built-in: git clone --filter=blob:none https://secure-server.example/repo
>>    Cloning into 'sw'...
>>    warning: templates not found in /home/aaron/share/git-core/templates
>>    11:03:26.857169 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>>    11:03:27.012104 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>>    11:03:27.049243 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>>    11:03:27.049270 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>>    11:03:27.053786 run-command.c:673       trace: run_command: 'git credential-msal get'
>>    11:03:27.952830 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>>    11:03:27.952849 http.c:849              => Send header: Authorization: Bearer <redacted>
>>    11:03:27.995419 http.c:849              <= Recv header: HTTP/1.1 200 OK
>>    11:03:28.230039 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>>    11:03:28.230208 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>>    11:03:28.230216 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>>    11:03:28.230221 http.c:849              => Send header: Authorization: Bearer <redacted>
>>    11:03:28.269085 http.c:849              <= Recv header: HTTP/1.1 200 OK
>>    11:03:28.684163 http.c:890              == Info: Reusing existing https: connection with host secure-server.example
>>    11:03:28.684379 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>>    11:03:28.684391 http.c:849              => Send header: Accept: application/x-git-upload-pack-result
>>    11:03:28.684393 http.c:849              => Send header: Authorization: Bearer <redacted>
>>    11:03:28.869546 run-command.c:673       trace: run_command: git index-pack --stdin --fix-thin '--keep=fetch-pack 43856 on dgx-spark' --promisor
>>    11:06:39.861237 run-command.c:673       trace: run_command: git -c fetch.negotiationAlgorithm=noop fetch origin --no-tags --no-write-fetch-head --recurse-submodules=no --filter=blob:none --stdin
>>    11:06:39.865981 run-command.c:673       trace: run_command: git remote-https origin https://secure-server.example/repo
>>    11:06:39.868039 run-command.c:673       trace: run_command: git-remote-https origin https://secure-server.example/repo
>>    11:07:30.412575 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>>    11:07:30.456285 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
>>    11:07:30.456318 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>>    11:07:30.456439 run-command.c:673       trace: run_command: 'git credential-cache get'
>>    11:07:30.461266 http.c:849              => Send header: GET repo/info/refs?service=git-upload-pack HTTP/1.1
>>    11:07:30.461282 http.c:849              => Send header: Authorization: Bearer <redacted>
>>    11:07:30.501628 http.c:849              <= Recv header: HTTP/1.1 200 OK
>>    11:07:34.725262 http.c:849              => Send header: POST repo/git-upload-pack HTTP/1.1
>>    11:07:34.725279 http.c:849              => Send header: Content-Type: application/x-git-upload-pack-request
>>    11:07:34.761407 http.c:849              <= Recv header: HTTP/1.1 401 Unauthorized
> 
> Okay, here we see the 401 error code.
> 
>>    11:07:34.761443 http.c:890              == Info: Bearer authentication problem, ignoring.
>>    11:07:34.761453 http.c:849              <= Recv header: WWW-Authenticate: Bearer error="invalid_request", error_description="No bearer token found in the request", msal-tenant-id="<tenant>", msal-client-id="<client>"
>>    11:07:34.761509 http.c:890              == Info: The requested URL returned error: 401
>>    11:07:34.761530 http.c:890              == Info: closing connection #0
>>    11:07:34.761913 run-command.c:673       trace: run_command: 'git credential-cache erase'
>>    11:07:34.761927 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-cache erase' 'git credential-cache erase'
>>    11:07:34.768069 git.c:502               trace: built-in: git credential-cache erase
>>    11:07:34.768690 run-command.c:673       trace: run_command: 'git credential-msal erase'
>>    11:07:34.768713 run-command.c:765       trace: start_command: /bin/sh -c 'git credential-msal erase' 'git credential-msal erase'
>>    11:07:34.772742 git.c:808               trace: exec: git-credential-msal erase
>>    11:07:34.772783 run-command.c:673       trace: run_command: git-credential-msal erase
>>    11:07:34.772819 run-command.c:765       trace: start_command: /usr/bin/git-credential-msal erase
> 
> And as we think that we've already set up authentication, this error
> code will cause us to think that the credentials that we've got are
> invalid. Consequently, we invalidate the credentials that we've stored.
> Naturally, this will cause _all_ subsequent requests to fail as we're no
> longer authenticated at all.
> 
>>    error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
>>    fatal: unable to write request to remote: Broken pipe
>>    fatal: could not fetch c4fff0229c9be06ecf576356a4d39a8a755b8d81 from promisor remote
>>    warning: Clone succeeded, but checkout failed.
>>    You can inspect what was checked out with 'git status'
>>    and retry with 'git restore --source=HEAD :/'
>>
>> Fix the immediate problem by including the authorization headers in the
>> probe_rpc() request as well.
>>
>> Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
>> Link: [1] https://github.com/Binary-Eater/git-credential-msal
>> ---
>> If http_auth.multistage were set in this scenario, then probe_rpc() would have
>> returned HTTP_REAUTH and this would have probably worked by generating a new
>> Bearer token. And we might need to use HTTP_REAUTH to handle the case where the
>> token expires between the initial request and this one, but I don't think
>> tackling that in this patch makes sense since the original Bearer token was
>> still valid and git just didn't try using it. And setting multistage (the
>> 'continue' parameter in git-credential(1)) doesn't make sense for Bearer tokens
>> since the token comes from an external agent.
> 
> This is something I was wondering about. Specifically, I saw the loop
> that we had around `HTTP_REAUTH`:
> 
> 		do {
> 			err = probe_rpc(rpc, &results);
> 			if (err == HTTP_REAUTH)
> 				credential_fill(the_repository, &http_auth, 0);
> 		} while (err == HTTP_REAUTH);
> 
> I then double-checked that we indeed get `HTTP_REAUTH` as an error code
> on a 401, so I was wondering why this doesn't lead to an infinite loop.
> I didn't connect it with the "multistage" thing though.

Right. I think we don't actually get HTTP_REAUTH because of this logic 
in handle_curl_result:

	else if (results->http_code == 401) {
		if ((http_auth.username && http_auth.password) ||\
		    (http_auth.authtype && http_auth.credential)) {
			if (http_auth.multistage) {
				credential_clear_secrets(&http_auth);
				return HTTP_REAUTH;
			}
			credential_reject(the_repository, &http_auth);
			if (always_auth_proactively())
				http_proactive_auth = PROACTIVE_AUTH_NONE;
			return HTTP_NOAUTH;
		} else {
			http_auth_methods &= ~CURLAUTH_GSSNEGOTIATE;
			if (results->auth_avail) {
				http_auth_methods &= results->auth_avail;
				http_auth_methods_restricted = 1;
			}
			return HTTP_REAUTH;
		}
	}

In this case, http_auth.authtype and http_auth.credential are set and 
http_auth.multistage is false. So it proceeds to call 
credential_reject() and return with HTTP_NOAUTH which causes the calling 
functions to fail immediately.

> In any case, I think this information would be useful to have in the
> commit message to help guide readers.
> 
>>   remote-curl.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/remote-curl.c b/remote-curl.c
>> index 69f919454a..1d0ae72521 100644
>> --- a/remote-curl.c
>> +++ b/remote-curl.c
>> @@ -877,6 +877,8 @@ static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
>>   	headers = curl_slist_append(headers, rpc->hdr_content_type);
>>   	headers = curl_slist_append(headers, rpc->hdr_accept);
>>   
>> +	headers = http_append_auth_header(&http_auth, headers);
>> +
>>   	curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0L);
>>   	curl_easy_setopt(slot->curl, CURLOPT_POST, 1L);
>>   	curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
> 
> The change looks simple enough, and matches what we do in `post_rpc()`
> itself.
> 
> It would be great to have a test case for this. It might be possible to
> use t5563-simple-http-auth as an example, where we already know to set
> up an HTTP server with authentication.

I'll look into that. It wasn't obvious to me how to make it hit this RPC 
case specifically but I'll see if I can figure out a way.

-- Aaron

> 
> Thanks!
> 
> Patrick

Re: [PATCH] remote-curl: Use auth for probe_rpc() requests too

[Aaron Plattner]

On 1/9/26 9:57 AM, Aaron Plattner wrote:
> On 1/9/26 6:51 AM, Patrick Steinhardt wrote:
[...]
>>> diff --git a/remote-curl.c b/remote-curl.c
>>> index 69f919454a..1d0ae72521 100644
>>> --- a/remote-curl.c
>>> +++ b/remote-curl.c
>>> @@ -877,6 +877,8 @@ static int probe_rpc(struct rpc_state *rpc, 
>>> struct slot_results *results)
>>>       headers = curl_slist_append(headers, rpc->hdr_content_type);
>>>       headers = curl_slist_append(headers, rpc->hdr_accept);
>>> +    headers = http_append_auth_header(&http_auth, headers);
>>> +
>>>       curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0L);
>>>       curl_easy_setopt(slot->curl, CURLOPT_POST, 1L);
>>>       curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
>>
>> The change looks simple enough, and matches what we do in `post_rpc()`
>> itself.
>>
>> It would be great to have a test case for this. It might be possible to
>> use t5563-simple-http-auth as an example, where we already know to set
>> up an HTTP server with authentication.
> 
> I'll look into that. It wasn't obvious to me how to make it hit this RPC 
> case specifically but I'll see if I can figure out a way.

I asked AI to try generating a test case for me and it discovered that 
the problem doesn't reproduce with Basic auth because git sets 
CURLOPT_USERNAME and CURLOPT_PASSWORD and curl implicitly includes those 
in subsequent requests without git having to add them explicitly. If we 
used CURLOPT_XOAUTH2_BEARER like imap-send.c does, then curl would 
presumably do the same thing behind the scenes.

That said, I'm not sure using that makes sense since the credential 
helper just tells git to use Bearer auth and what the token is, but not 
whether it's OAuth2 or some other kind of token. I don't know if that 
matters. Rahul, do you have any opinions there since you're familiar 
with this stuff than I am?

Anyway, the test it came up with creates a repository with 2000 branches 
to get the reply to hit the large_request=1 case and then uses a simple 
credential helper with a dummy Bearer token to trigger the problem. If 
you think the current fix and that test scenario sound reasonable, I'll 
clean it up and send out a v2.

-- Aaron

Re: [PATCH] remote-curl: Use auth for probe_rpc() requests too

[Patrick Steinhardt]

On Fri, Jan 09, 2026 at 10:39:10AM -0800, Aaron Plattner wrote:
> On 1/9/26 9:57 AM, Aaron Plattner wrote:
> > On 1/9/26 6:51 AM, Patrick Steinhardt wrote:
> [...]
> > > > diff --git a/remote-curl.c b/remote-curl.c
> > > > index 69f919454a..1d0ae72521 100644
> > > > --- a/remote-curl.c
> > > > +++ b/remote-curl.c
> > > > @@ -877,6 +877,8 @@ static int probe_rpc(struct rpc_state *rpc,
> > > > struct slot_results *results)
> > > >       headers = curl_slist_append(headers, rpc->hdr_content_type);
> > > >       headers = curl_slist_append(headers, rpc->hdr_accept);
> > > > +    headers = http_append_auth_header(&http_auth, headers);
> > > > +
> > > >       curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0L);
> > > >       curl_easy_setopt(slot->curl, CURLOPT_POST, 1L);
> > > >       curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
> > > 
> > > The change looks simple enough, and matches what we do in `post_rpc()`
> > > itself.
> > > 
> > > It would be great to have a test case for this. It might be possible to
> > > use t5563-simple-http-auth as an example, where we already know to set
> > > up an HTTP server with authentication.
> > 
> > I'll look into that. It wasn't obvious to me how to make it hit this RPC
> > case specifically but I'll see if I can figure out a way.
> 
> I asked AI to try generating a test case for me and it discovered that the
> problem doesn't reproduce with Basic auth because git sets CURLOPT_USERNAME
> and CURLOPT_PASSWORD and curl implicitly includes those in subsequent
> requests without git having to add them explicitly. If we used
> CURLOPT_XOAUTH2_BEARER like imap-send.c does, then curl would presumably do
> the same thing behind the scenes.
> 
> That said, I'm not sure using that makes sense since the credential helper
> just tells git to use Bearer auth and what the token is, but not whether
> it's OAuth2 or some other kind of token. I don't know if that matters.
> Rahul, do you have any opinions there since you're familiar with this stuff
> than I am?
> 
> Anyway, the test it came up with creates a repository with 2000 branches to
> get the reply to hit the large_request=1 case and then uses a simple
> credential helper with a dummy Bearer token to trigger the problem. If you
> think the current fix and that test scenario sound reasonable, I'll clean it
> up and send out a v2.

Creating 2000 branches can be done efficiently via a single
git-update-ref(1) call, so this wouldn't cause the test to become
prohibitively expensive. And if that manages to reproduce the problem it
sounds like a reasonable way forward.

Thanks!

Patrick