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release 0.5.10: a setuid, setgid or file-capability binary ignores the environment and loads no GL - #67
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…e environment and loads no GL open_drm_auto() read DRM_DEVICE whenever the process was not root. A binary that gained privilege when it started (setuid, setgid, or CAP_SYS_ADMIN through file capabilities) runs with an environment the invoking user sets. Read DRM_DEVICE and the DRMTAP_* variables with secure_getenv(), which returns nothing for such a binary, and do not load the GL libraries there: they read their own environment. A scanout that needs a GPU detile fails closed in such a process with an error that says why. README, SECURITY.md, CONTRIBUTING.md, the header and a helper comment now say what the code does.
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Navigate logical layers of code changes, visualize relationships, and explore their blast radius. 🧰 Additional context used📚 Code guidelines (1)📝 SummarySummary by CodeRabbit
WalkthroughVersion 0.5.10 uses secure environment access for selected settings and prevents GL library loading in secure-execution processes. When CPU deswizzling cannot handle a framebuffer modifier in that context, capture returns an error. Documentation and release metadata describe these changes. ChangesSecure-execution handling
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant drm_grab
participant load_gl_libraries
participant getauxval
drm_grab->>load_gl_libraries: request EGL/GLES loading
load_gl_libraries->>getauxval: check AT_SECURE
getauxval-->>load_gl_libraries: secure-execution status
load_gl_libraries-->>drm_grab: return -3 when secure
drm_grab->>drm_grab: CPU deswizzle or return ENOTSUP
Merge Risk: 🟡 Moderate · up to Secure-execution capture can return corrupted frames for CPU-mappable tiled scanouts without declared modifiers. Reject unknown layouts in both implementations before merging; unprivileged helper-based capture remains an alternative. Security Architecture ReviewSecurity architecture risk: 🟡 Moderate · up to The new restrictions strengthen privileged execution. However, disabling EGL also makes unknown-layout scanouts take a successful linear fallback, potentially returning undecoded pixels instead of triggering downstream recovery. Explicit device authorization remains the caller’s responsibility. Retained concerns
Security review detailsSecurity Blast Radius
Security Findings and Attack Paths
Trust Boundaries and Controls
Resilience and Maintainability Implications
Hardening Proposals
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 44.44% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 18 functions across 10 files. (9 skipped: 9 unsupported.)
✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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Actionable comments posted: 1
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @src/gpu_egl.c:
- Around line 147-148: Update the CPU-mapped scanout handling in both C
implementations so DRM_FORMAT_MOD_INVALID is not treated as linear when EGL is
unavailable. Restrict the linear classification to explicitly linear modifiers,
and return -ENOTSUP with an error when the modifier is invalid instead of
reducing or returning the raw mapped frame.
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Configuration used: Organization UI
Review profile: ASSERTIVE
Plan: Advanced
Run ID: 241e8a8d-254d-4483-98e2-4e11a059890b
📒 Files selected for processing (19)
CHANGELOG.mdREADME.mdSECURITY.mdbindings/rust/libdrmtap-sys/Cargo.tomlbindings/rust/libdrmtap-sys/README.mdbindings/rust/libdrmtap-sys/csrc/drm_grab.cbindings/rust/libdrmtap-sys/csrc/drmtap-helper.cbindings/rust/libdrmtap-sys/csrc/drmtap.cbindings/rust/libdrmtap-sys/csrc/drmtap.hbindings/rust/libdrmtap-sys/csrc/gpu_egl.cbindings/rust/libdrmtap/Cargo.tomlbindings/rust/libdrmtap/README.mdcontrib/integrations/rustdesk/README.mdhelper/drmtap-helper.cinclude/drmtap.hmeson.buildsrc/drm_grab.csrc/drmtap.csrc/gpu_egl.c
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📜 Review details
⏰ Context from checks skipped due to timeout. (8)
- GitHub Check: Build & Test (Ubuntu 22.04)
- GitHub Check: Rust crate (libdrmtap-sys + libdrmtap)
- GitHub Check: Static Analysis
- GitHub Check: Build & Test (Ubuntu 24.04)
- GitHub Check: Version & crate-source coherence
- GitHub Check: Analyze (rust)
- GitHub Check: Analyze (actions)
- GitHub Check: Analyze (c-cpp)
🧰 Additional context used
📓 Path-based instructions (2)
Source excerpt: | Rule | Convention | |---|---| | Indent | 4 spaces, never tabs | | Naming: functions | `snake_case`, prefixed `drmtap_` for public API | | Naming: variables | `snake_case` | | Naming: macros/constants | `UPPER_SNAKE_CASE`,...
📄 CodeRabbit inference engine (AGENTS.md)
Files:
helper/drmtap-helper.cbindings/rust/libdrmtap-sys/csrc/gpu_egl.csrc/drmtap.cinclude/drmtap.hbindings/rust/libdrmtap-sys/csrc/drmtap-helper.cbindings/rust/libdrmtap-sys/csrc/drm_grab.cbindings/rust/libdrmtap-sys/csrc/drmtap.hbindings/rust/libdrmtap-sys/csrc/drmtap.csrc/drm_grab.csrc/gpu_egl.c
Source excerpt: Source excerpt: Public API changes → update `include/drmtap.h` comments
📄 CodeRabbit inference engine (AGENTS.md)
Files:
include/drmtap.h
🪛 Clang (14.0.6)
src/drmtap.c
[note] 111-111: +1, including nesting penalty of 0, nesting level increased to 1
(clang)
[note] 111-111: +1
(clang)
bindings/rust/libdrmtap-sys/csrc/drm_grab.c
[warning] 109-109: variable name 'e' is too short, expected at least 3 characters
(readability-identifier-length)
bindings/rust/libdrmtap-sys/csrc/drmtap.c
[note] 111-111: +1, including nesting penalty of 0, nesting level increased to 1
(clang)
[note] 111-111: +1
(clang)
src/drm_grab.c
[warning] 109-109: variable name 'e' is too short, expected at least 3 characters
(readability-identifier-length)
🪛 LanguageTool
contrib/integrations/rustdesk/README.md
[grammar] ~65-~65: Ensure spelling is correct
Context: ...he consumer binary itself gets no GPU detile since 0.5.10
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
bindings/rust/libdrmtap/README.md
[grammar] ~114-~114: Ensure spelling is correct
Context: ...-capability process, so there the EGL detile is unavailable too: grab through the he...
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
CHANGELOG.md
[grammar] ~22-~22: Ensure spelling is correct
Context: ...nger loads the GL libraries for the EGL detile: they are third-party code that reads it...
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
[grammar] ~26-~26: Ensure spelling is correct
Context: ...es no modifier is read as linear. 0.5.9 detiled in that process. A consumer that needs ...
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
[style] ~27-~27: Consider using “who” when you are referring to a person instead of an object.
Context: ...5.9 detiled in that process. A consumer that needs the detile runs unprivileged and ...
(THAT_WHO)
[grammar] ~27-~27: Ensure spelling is correct
Context: ...that process. A consumer that needs the detile runs unprivileged and grabs through the...
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
bindings/rust/libdrmtap-sys/README.md
[grammar] ~51-~51: Ensure spelling is correct
Context: ...-capability process, so there the EGL detile is unavailable too: grab through the he...
(QB_NEW_EN_ORTHOGRAPHY_ERROR_IDS_1)
🔇 Additional comments (4)
bindings/rust/libdrmtap-sys/Cargo.toml (1)
3-3: LGTM!bindings/rust/libdrmtap/Cargo.toml (1)
3-3: LGTM!Also applies to: 19-19
CHANGELOG.md (1)
9-35: LGTM!Also applies to: 1026-1026
meson.build (1)
4-4: 🎯 Functional CorrectnessThe public header defines version
0.5.10, matchingmeson.build. The Meson version assertion does not fail.
1 participant
secure_getenv for
DRM_DEVICEand theDRMTAP_*variables, and no GL in a setuid, setgid or file-capability process.measured on an i915 box with a probe that has
cap_sys_admin+ep:DRM_DEVICEandDRMTAP_DEBUGand loads libEGL duringdrmtap_grab_mappedthe helper loads no GL and is not affected. details in the CHANGELOG
[0.5.10]section.