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ifcurl-preview.service: correct misleading execve comment

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execve is actually permitted — it arrives via @default which is included in
@system-service.  The main service needs it for GitPython's git CLI calls.
Blocking execve only in render subprocesses would require per-process seccomp,
which is not worth the complexity for this threat model.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Bruno Postle 2026-04-25 08:30:41 +01:00
parent 4b32726f87
commit fef6c16946
2 changed files with 4 additions and 4 deletions
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2
.beads/issues.jsonl
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@ -3,7 +3,7 @@
{"id":"ifcurl-4l7","title":"viewer.html: scale= URLs don't load in orthographic mode","description":"applyCameraParam() reads the camera= and fov= parameters from the URL and applies them, but never reads scale= or switches the camera to orthographic (parallel) projection. URLs like ?camera=...\u0026scale=50 will load in perspective mode instead of orthographic. The OBC OrthoPerspectiveCamera can switch modes, but the code path to set parallel projection and apply the scale value is missing from applyCameraParam.","status":"closed","priority":1,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T09:04:51Z","created_by":"Bruno Postle","updated_at":"2026-04-24T10:56:29Z","started_at":"2026-04-24T10:50:19Z","closed_at":"2026-04-24T10:56:29Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-4l7","title":"viewer.html: scale= URLs don't load in orthographic mode","description":"applyCameraParam() reads the camera= and fov= parameters from the URL and applies them, but never reads scale= or switches the camera to orthographic (parallel) projection. URLs like ?camera=...\u0026scale=50 will load in perspective mode instead of orthographic. The OBC OrthoPerspectiveCamera can switch modes, but the code path to set parallel projection and apply the scale value is missing from applyCameraParam.","status":"closed","priority":1,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T09:04:51Z","created_by":"Bruno Postle","updated_at":"2026-04-24T10:56:29Z","started_at":"2026-04-24T10:50:19Z","closed_at":"2026-04-24T10:56:29Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-362","title":"Add missing server-config files: gitconfig-ifcmerge and gitattributes","description":"forgejo/README.md documents deploying two files that don't exist in the repo: forgejo/server-config/gitconfig-ifcmerge and forgejo/server-config/gitattributes. Both are required for the ifcmerge git merge driver to work in bare Forgejo repos. The README even includes 'sudo cp forgejo/server-config/gitattributes /etc/gitattributes' and 'sudo git config --system include.path .../gitconfig-ifcmerge', but the files themselves are absent. Anyone following the deployment instructions will hit a 'file not found' error. Need to create both files with the content described in the README.","status":"closed","priority":1,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T09:04:31Z","created_by":"Bruno Postle","updated_at":"2026-04-24T10:51:47Z","started_at":"2026-04-24T10:50:15Z","closed_at":"2026-04-24T10:51:47Z","close_reason":"Files already exist: forgejo/server-config/gitconfig-ifcmerge and gitattributes are both present and correct. Missed in initial review.","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-362","title":"Add missing server-config files: gitconfig-ifcmerge and gitattributes","description":"forgejo/README.md documents deploying two files that don't exist in the repo: forgejo/server-config/gitconfig-ifcmerge and forgejo/server-config/gitattributes. Both are required for the ifcmerge git merge driver to work in bare Forgejo repos. The README even includes 'sudo cp forgejo/server-config/gitattributes /etc/gitattributes' and 'sudo git config --system include.path .../gitconfig-ifcmerge', but the files themselves are absent. Anyone following the deployment instructions will hit a 'file not found' error. Need to create both files with the content described in the README.","status":"closed","priority":1,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T09:04:31Z","created_by":"Bruno Postle","updated_at":"2026-04-24T10:51:47Z","started_at":"2026-04-24T10:50:15Z","closed_at":"2026-04-24T10:51:47Z","close_reason":"Files already exist: forgejo/server-config/gitconfig-ifcmerge and gitattributes are both present and correct. Missed in initial review.","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-ndf","title":"gitconfig-ifcmerge: update to use ifcmerge --prioritise-local instead of swapping LOCAL/REMOTE","description":"The current gitconfig-ifcmerge uses the old technique of swapping the order of %A and %B arguments to preserve the base branch's STEP ID space:\n\n driver = ifcmerge %O %A %B %L (standard)\n driver = ifcmerge %O %B %A %L (ours variant)\n\nBonsai's current ifcgit code (tool/ifcgit.py, config_ifcmerge) uses the newer --prioritise-local flag instead:\n\n ifcmerge --prioritise-local $BASE $LOCAL $REMOTE $MERGED\n\nThe --prioritise-local flag tells ifcmerge to preserve LOCAL's STEP ID space without needing to swap argument order. This is cleaner, more readable, and follows the canonical ifcmerge interface.\n\nThe gitconfig-ifcmerge needs updating to:\n driver = ifcmerge --prioritise-local %O %A %B %A\n\n(where %A is both LOCAL and the output file — git merge drivers write their result to %A)\n\nThe ifcmerge_ours variant (for rebase direction where base branch arrives as %B) would become:\n driver = ifcmerge --prioritise-local %O %B %A %B\n\nVerify that the --prioritise-local flag exists in the version of ifcmerge being used before merging.","status":"closed","priority":2,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-25T06:06:59Z","created_by":"Bruno Postle","updated_at":"2026-04-25T06:41:59Z","closed_at":"2026-04-25T06:41:59Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-ndf","title":"gitconfig-ifcmerge: update to use ifcmerge --prioritise-local instead of swapping LOCAL/REMOTE","description":"The current gitconfig-ifcmerge uses the old technique of swapping the order of %A and %B arguments to preserve the base branch's STEP ID space:\n\n driver = ifcmerge %O %A %B %L (standard)\n driver = ifcmerge %O %B %A %L (ours variant)\n\nBonsai's current ifcgit code (tool/ifcgit.py, config_ifcmerge) uses the newer --prioritise-local flag instead:\n\n ifcmerge --prioritise-local $BASE $LOCAL $REMOTE $MERGED\n\nThe --prioritise-local flag tells ifcmerge to preserve LOCAL's STEP ID space without needing to swap argument order. This is cleaner, more readable, and follows the canonical ifcmerge interface.\n\nThe gitconfig-ifcmerge needs updating to:\n driver = ifcmerge --prioritise-local %O %A %B %A\n\n(where %A is both LOCAL and the output file — git merge drivers write their result to %A)\n\nThe ifcmerge_ours variant (for rebase direction where base branch arrives as %B) would become:\n driver = ifcmerge --prioritise-local %O %B %A %B\n\nVerify that the --prioritise-local flag exists in the version of ifcmerge being used before merging.","status":"closed","priority":2,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-25T06:06:59Z","created_by":"Bruno Postle","updated_at":"2026-04-25T06:41:59Z","closed_at":"2026-04-25T06:41:59Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-qjd","title":"render_diff: auto-fit camera to changed elements, not whole model","description":"When rendering a diff of a large building model, the auto-fit camera fits to the entire head model. A wall added to one corner of a multi-storey building would appear as a tiny green speck. The camera should instead zoom to the bounding box of just the added + modified + removed elements so the changed area fills the viewport.\n\nImplementation sketch:\n- In render_diff(), after adding all shapes to plotter1, call plotter1.reset_camera() as now, but also compute the bounds of only the diff-coloured meshes (added + modified) and re-fit to those bounds.\n- For pass 2 (removed elements), the elements are already isolated in the iterator, so reset_camera() naturally fits to them. The pass 1 camera capture then needs to consider that pass 2 might be out of that frustum.\n- A combined approach: compute the bounding box union of added + modified + removed element meshes, then set the camera to fit that box with a small margin. This is the camera used for both passes.\n- pyvista Plotter has plotter.reset_camera(bounds=(xmin,xmax,ymin,ymax,zmin,zmax)) which can fit to an explicit box.\n- The bounds can be accumulated during the _add_shape loop for diff-coloured elements.\n\nAcceptance: a single modified wall in a large building renders with the wall clearly visible and filling most of the image.","status":"open","priority":2,"issue_type":"bug","owner":"bruno@postle.net","created_at":"2026-04-25T06:06:39Z","created_by":"Bruno Postle","updated_at":"2026-04-25T06:06:39Z","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-qjd","title":"render_diff: auto-fit camera to changed elements, not whole model","description":"When rendering a diff of a large building model, the auto-fit camera fits to the entire head model. A wall added to one corner of a multi-storey building would appear as a tiny green speck. The camera should instead zoom to the bounding box of just the added + modified + removed elements so the changed area fills the viewport.\n\nImplementation sketch:\n- In render_diff(), after adding all shapes to plotter1, call plotter1.reset_camera() as now, but also compute the bounds of only the diff-coloured meshes (added + modified) and re-fit to those bounds.\n- For pass 2 (removed elements), the elements are already isolated in the iterator, so reset_camera() naturally fits to them. The pass 1 camera capture then needs to consider that pass 2 might be out of that frustum.\n- A combined approach: compute the bounding box union of added + modified + removed element meshes, then set the camera to fit that box with a small margin. This is the camera used for both passes.\n- pyvista Plotter has plotter.reset_camera(bounds=(xmin,xmax,ymin,ymax,zmin,zmax)) which can fit to an explicit box.\n- The bounds can be accumulated during the _add_shape loop for diff-coloured elements.\n\nAcceptance: a single modified wall in a large building renders with the wall clearly visible and filling most of the image.","status":"closed","priority":2,"issue_type":"bug","owner":"bruno@postle.net","created_at":"2026-04-25T06:06:39Z","created_by":"Bruno Postle","updated_at":"2026-04-25T06:57:06Z","closed_at":"2026-04-25T06:57:06Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-zxs","title":"sandbox.py: add seccomp filter to block execve and socket in render subprocess","description":"The subprocess isolation in sandbox.py (ifcurl-vm5) prevents DoS but not RCE: if a crafted IFC file achieves code execution inside the render child, that child still has full access to execve and the network. A seccomp BPF filter applied at the start of _worker() would block the two most useful post-exploitation steps even under active code execution.\n\nThe filter should:\n- Block execve/execveat (cannot exec a shell or any binary)\n- Block socket() for AF_INET/AF_INET6/AF_UNIX (cannot open a reverse shell or connect to the Forgejo Unix socket)\n- Allow clone/fork (ifcopenshell's geom.iterator spawns its own worker processes)\n- Allow everything else needed by Python + ifcopenshell + pyvista\n\nThe python-seccomp library (pip install seccomp, wraps libseccomp) is the cleanest way to do this. The filter would be installed via resource.setrlimit companion code already present in sandbox._worker().\n\nThe main risk is over-filtering: if the seccomp policy blocks a syscall that ifcopenshell or pyvista needs, renders fail with EPERM. The policy needs to be validated against the full render path (including the geometry iterator subprocesses, which inherit the filter across fork).\n\nAcceptance criteria:\n- A render subprocess cannot exec /bin/sh even with arbitrary code execution (verified by replacing fn with a ctypes execve call — should get EPERM/killed, not a shell)\n- Normal renders continue to produce correct PNG output\n- The seccomp library is optional (graceful fallback if libseccomp is absent, e.g. on macOS or minimal containers)","status":"open","priority":2,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-24T20:47:00Z","created_by":"Bruno Postle","updated_at":"2026-04-24T20:47:00Z","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-zxs","title":"sandbox.py: add seccomp filter to block execve and socket in render subprocess","description":"The subprocess isolation in sandbox.py (ifcurl-vm5) prevents DoS but not RCE: if a crafted IFC file achieves code execution inside the render child, that child still has full access to execve and the network. A seccomp BPF filter applied at the start of _worker() would block the two most useful post-exploitation steps even under active code execution.\n\nThe filter should:\n- Block execve/execveat (cannot exec a shell or any binary)\n- Block socket() for AF_INET/AF_INET6/AF_UNIX (cannot open a reverse shell or connect to the Forgejo Unix socket)\n- Allow clone/fork (ifcopenshell's geom.iterator spawns its own worker processes)\n- Allow everything else needed by Python + ifcopenshell + pyvista\n\nThe python-seccomp library (pip install seccomp, wraps libseccomp) is the cleanest way to do this. The filter would be installed via resource.setrlimit companion code already present in sandbox._worker().\n\nThe main risk is over-filtering: if the seccomp policy blocks a syscall that ifcopenshell or pyvista needs, renders fail with EPERM. The policy needs to be validated against the full render path (including the geometry iterator subprocesses, which inherit the filter across fork).\n\nAcceptance criteria:\n- A render subprocess cannot exec /bin/sh even with arbitrary code execution (verified by replacing fn with a ctypes execve call — should get EPERM/killed, not a shell)\n- Normal renders continue to produce correct PNG output\n- The seccomp library is optional (graceful fallback if libseccomp is absent, e.g. on macOS or minimal containers)","status":"open","priority":2,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-24T20:47:00Z","created_by":"Bruno Postle","updated_at":"2026-04-24T20:47:00Z","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-9cr","title":"ifc:// URLs in Forgejo issues and PR comments not documented as a collaboration tool","description":"Forgejo's markdown extension renders ifc:// URLs as clickable 3D preview images in file README views, but it works equally in issue bodies, PR descriptions, and comment threads — which is where the actual collaboration happens. This is potentially the most useful feature: a reviewer can paste an ifc:// URL in a PR comment and everyone in the thread sees the 3D view inline. This is not mentioned anywhere in README.md, forgejo/README.md, or SPECIFICATION.md. Add a 'Collaboration workflow' section to the README showing: (1) navigate to view in viewer, (2) copy URL from address bar, (3) paste as [label](ifc://...) in a Forgejo comment/issue, (4) collaborators click the preview image to open the view.","status":"closed","priority":2,"issue_type":"task","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T11:03:44Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:47:24Z","started_at":"2026-04-24T11:14:59Z","closed_at":"2026-04-24T11:47:24Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-9cr","title":"ifc:// URLs in Forgejo issues and PR comments not documented as a collaboration tool","description":"Forgejo's markdown extension renders ifc:// URLs as clickable 3D preview images in file README views, but it works equally in issue bodies, PR descriptions, and comment threads — which is where the actual collaboration happens. This is potentially the most useful feature: a reviewer can paste an ifc:// URL in a PR comment and everyone in the thread sees the 3D view inline. This is not mentioned anywhere in README.md, forgejo/README.md, or SPECIFICATION.md. Add a 'Collaboration workflow' section to the README showing: (1) navigate to view in viewer, (2) copy URL from address bar, (3) paste as [label](ifc://...) in a Forgejo comment/issue, (4) collaborators click the preview image to open the view.","status":"closed","priority":2,"issue_type":"task","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T11:03:44Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:47:24Z","started_at":"2026-04-24T11:14:59Z","closed_at":"2026-04-24T11:47:24Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}
{"id":"ifcurl-n00","title":"Forgejo markdown previews fail silently for private repos — no auth path from preview service","description":"The Forgejo markdown extension generates \u003cimg src='http://localhost:8000/preview?url=ifc://...'\u003e tags. The preview service fetches the IFC file server-side using GET /preview with no authentication. For private repos, this returns HTTP 404 or 403 and the preview image shows as broken. There is no mechanism for the Forgejo markdown renderer to pass the user's session token to the preview service. Options to investigate: (1) the Forgejo integration could pass a signed request token; (2) the preview service could run as the Forgejo git user (which has read access to all repos); (3) SSH-based fetch from the service using the Forgejo server's own key. The current state is a silent failure that will confuse users.","status":"closed","priority":2,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T11:03:39Z","created_by":"Bruno Postle","updated_at":"2026-04-24T12:39:46Z","started_at":"2026-04-24T11:56:30Z","closed_at":"2026-04-24T12:39:46Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0} {"id":"ifcurl-n00","title":"Forgejo markdown previews fail silently for private repos — no auth path from preview service","description":"The Forgejo markdown extension generates \u003cimg src='http://localhost:8000/preview?url=ifc://...'\u003e tags. The preview service fetches the IFC file server-side using GET /preview with no authentication. For private repos, this returns HTTP 404 or 403 and the preview image shows as broken. There is no mechanism for the Forgejo markdown renderer to pass the user's session token to the preview service. Options to investigate: (1) the Forgejo integration could pass a signed request token; (2) the preview service could run as the Forgejo git user (which has read access to all repos); (3) SSH-based fetch from the service using the Forgejo server's own key. The current state is a silent failure that will confuse users.","status":"closed","priority":2,"issue_type":"bug","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-24T11:03:39Z","created_by":"Bruno Postle","updated_at":"2026-04-24T12:39:46Z","started_at":"2026-04-24T11:56:30Z","closed_at":"2026-04-24T12:39:46Z","close_reason":"Closed","dependency_count":0,"dependent_count":0,"comment_count":0}

6
forgejo/server-config/ifcurl-preview.service
View file

@ -38,9 +38,9 @@ RestartSec=5
# setuid binaries or capabilities. # setuid binaries or capabilities.
# #
# SystemCallFilter: allow the syscalls a Python/C-extension process needs # SystemCallFilter: allow the syscalls a Python/C-extension process needs
# (@system-service covers the common POSIX set; @process covers fork/clone # (@system-service covers the common POSIX set including execve via @default;
# which ifcopenshell's geometry iterator requires). execve/execveat are NOT # @process adds fork/clone for ifcopenshell's geometry iterator). execve is
# in either set, so an attacker with code execution cannot exec a shell. # permitted because the main process needs it for git CLI calls (GitPython).
# The filter applies to child processes too (inherited across fork). # The filter applies to child processes too (inherited across fork).
# #
# RestrictAddressFamilies: the service only needs TCP/UDP to reach git hosts. # RestrictAddressFamilies: the service only needs TCP/UDP to reach git hosts.