Switch system distro build to FreeRDP 3.x (3.26.0) (Phase 3 / 3)

[benhillis]

Switch the WSLg system distro build from the FreeRDP 2.4.0-era microsoft/FreeRDP-mirror fork to upstream FreeRDP 3.x (tag 3.26.0).

This is PR 1 of 3 in a coordinated migration. PR 2 (microsoft/weston-mirror#163) ports the weston rdp-backend to the FreeRDP 3.x server API. PR 3 (to be opened) will switch the ADO pipeline's FreeRDP repo resource from microsoft/FreeRDP-mirror to FreeRDP/FreeRDP@3.26.0. This PR alone is a no-op against the current pipeline.

Why

The WSLg-pinned microsoft/FreeRDP-mirror's working branch is built from a fork of FreeRDP 2.4.0 (Aug 2023), and the upstream 2.x line was declared EOL by the FreeRDP project. Only 3.x is supported. Tracking advisories from 2023-08 onward: 11 HIGH-severity CVEs in 2026 alone (e.g. CVE-2026-26955 OOB write, CVE-2026-31806 nsc heap overflow, CVE-2026-44420 cliprdr server heap overflow, CVE-2026-45700 planar bitmap decoder overflow). All are patched only in 3.x. Since WSLg runs the server side of RDP, the cliprdr / rdpgfx / cache PDU handlers in particular are reachable from a malicious or compromised mstsc client over TCP loopback or vsock.

Diff

Dockerfile      | 10 +++++++---
WSLGd/main.cpp  |  6 +++++-
WSLGd/precomp.h |  1 +
3 files changed, 13 insertions(+), 4 deletions(-)

Dockerfile

• ARG FREERDP_VERSION=2 -> =3 (also flips the debuginfo strip target from FreeRDP2.list to FreeRDP3.list).
• New cmake flags (each became REQUIRED-by-default in 3.x and is not desired for WSLg):
  • -DWITH_FFMPEG=OFF
  • -DWITH_DSP_FFMPEG=OFF
  • -DWITH_VIDEO_FFMPEG=OFF
  • -DWITH_SWSCALE=OFF
  • -DWITH_KRB5=OFF
• Removed -DWITH_CHANNEL_GFXREDIR=ON and -DWITH_CHANNEL_RDPAPPLIST=ON. WITH_CHANNEL_GFXREDIR is vestigial in upstream FreeRDP 3.x (the cmakedefine exists in config.h.in but no cmake logic ever sets it); rdpapplist is not a FreeRDP channel at all (the rdpapplist plugin is built standalone from wslg/rdpapplist/). Replaced with -DCHANNEL_GFXREDIR=ON, the correct upstream knob for enabling the gfxredir dynamic channel (default OFF).

WSLGd/main.cpp + WSLGd/precomp.h

IniFile_GetSectionKeyNames(..., size_t* count) signature change in WinPR 3.x (was int*). Guarded with #if WINPR_VERSION_MAJOR >= 3 so the file still compiles against WinPR 2.x. Added explicit #include <winpr/version.h> in precomp.h.

Validation

End-to-end Docker build of the system distro succeeds against FreeRDP/FreeRDP@3.26.0. Verified in the built image:

• /usr/lib/libfreerdp3.so.3.26.0
• /usr/lib/libwinpr3.so.3.26.0
• /usr/lib/libfreerdp-server3.so.3.26.0, exports gfxredir_server_context_{new,free}, audin_server_context_new, rdpsnd_server_context_new, etc.
• /usr/lib/rdpapplist/librdpapplist-server.so, exports rdpapplist_server_context_{new,free}.
• /usr/lib/libweston-9/rdp-backend.so links against libfreerdp3.so.3 / libwinpr3.so.3 / libfreerdp-server3.so.3.

Runtime smoke test (xfreerdp loopback + Windows mstsc) is pending and will be performed before any of the three PRs is marked "Ready for review".

Known limitations (tracked as follow-up)

• RDP audio is disabled on FreeRDP 3.x. The audin_server_context / rdpsnd_server_context APIs were rewritten in 3.x to a PDU-callback model; the wslg port is in flight in rdp-backend: port to FreeRDP 3.x server API (Phase 3 / 3) weston-mirror#163 as a stub commit and a proper port will land before that PR is marked Ready.
• The file-cert TLS path (rdp.ini cert-file/key-file) currently errors out on FreeRDP 3.x. WSLg in production uses the session-generated TLS path via Hyper-V vsock, which is fully functional.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Migrates WSLg system distro build scaffolding toward upstream FreeRDP 3.x (3.26.0), including Docker build configuration updates and a small WinPR API compatibility change in WSLGd.

Changes:

• Update Dockerfile to default to FreeRDP v3 and adjust FreeRDP CMake feature knobs for 3.x.
• Make WSLGd compile against WinPR 2.x and 3.x by handling the IniFile_GetSectionKeyNames count type change.
• Add WinPR version header include to support version-based compilation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
Dockerfile	Defaults build to FreeRDP 3 and updates FreeRDP CMake options to match 3.x expectations.
WSLGd/main.cpp	Adapts to WinPR 3.x signature change for INI key enumeration count type.
WSLGd/precomp.h	Includes WinPR version header needed for WINPR_VERSION_MAJOR checks.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[benhillis]

Addressed code-review finding: cgmanifest.json still listed FreeRDP commit 39f56443 (2.x). Bumped to 3f6d7cb1 (3.26.0) to match what we actually build. See 0dfa0ac.

This was non-functional (wouldn't have broken the build) but would have made Component Governance scanning report the wrong upstream version and potentially raise stale CVE alerts against retired FreeRDP 2.x.