fix: pin workspace agent API client to intended agent (#26600) - #26622
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Backport of #26600 to release/2.29. The workspace agent API client followed HTTP redirects and trusted the redirected host, letting a malicious agent bounce a coderd request onto a different agent's unauthenticated port-4 API (cross-tenant file read/write and RCE). apiClient now refuses redirects and pins every dial to the intended agent address, and the task app / scaletest clients share AppHTTPClient, which blocks redirects too. The upstream change was built on a separate request-context refactor of apiClient that is not present on this release branch, so the redirect block and agent-address pinning are applied to the existing apiClient() here and the request-context-bounded dial test is omitted. The generated agent-conn mock also needed its net/http import for the new AppHTTPClient method. (cherry picked from commit eeb2624)
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Backport of #26600 to
release/2.29.Original PR: #26600 - fix: pin workspace agent API client to intended agent
Merge commit: eeb2624
Requested by: @ethanndickson
What this fixes
The workspace agent API client followed HTTP redirects and trusted the redirected host, letting a malicious agent bounce a coderd request onto a different agent's unauthenticated port-4 API (cross-tenant file read/write and RCE, Cure53 CODAGT-668).
apiClientnow refuses redirects and pins every dial to the intended agent address, and the task-app / scaletest clients shareAppHTTPClient, which blocks redirects too.Conflict resolution
This 2.29 ESR backport was resolved using the existing
release/2.32backport (#26612) as a reference; that resolution applies cleanly here. #26600 was built on a separate request-context refactor ofapiClientthat is not present on this release branch, so the redirect block and agent-address pinning are applied to the existingapiClient(), and the request-context-bounded dial test (which depends on that refactor) is omitted. This branch had noagentconn_test.go, so the redirect regression tests are added as a newagentconn_test.go. The generated agent-conn mock additionally required itsnet/httpimport for the newAppHTTPClientmethod.