feat(core): add CDI policy resolver

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

Cargo.lock

@@ -83,6 +83,7 @@ rustix = { version = "1.1", features = ["process"] }
 socket2 = "0.6"
 
 # Serialization
+container-device-interface = { git = "https://github.com/cncf-tags/container-device-interface-rs", rev = "b8a056e92dbd159423c129cd306c93e410651b18" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 serde_yml = { package = "noyalib", version = "0.0.28", default-features = false, features = ["std", "compat-serde-yaml"] }

Cargo.toml

@@ -45,6 +45,9 @@ tempfile = { version = "3", optional = true }
 nix = { workspace = true }
 rustix = { workspace = true }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+container-device-interface = { workspace = true }
+
 [features]
 default = ["telemetry"]
 ## Compile in anonymous telemetry emission support. On by default; disable with

crates/openshell-core/Cargo.toml

@@ -0,0 +1,131 @@
+// SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+//! Shared CDI context schema and resolver helpers.
+
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+pub const CDI_CONTEXT_VERSION: u32 = 1;
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct CdiContext {
+    pub version: u32,
+    pub selected_devices: Vec<String>,
+    pub spec_dirs: Vec<CdiSpecDirectory>,
+}
+
+impl CdiContext {
+    #[must_use]
+    pub fn new(selected_devices: Vec<String>, spec_dirs: Vec<CdiSpecDirectory>) -> Self {
+        Self {
+            version: CDI_CONTEXT_VERSION,
+            selected_devices,
+            spec_dirs,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct CdiSpecDirectory {
+    pub path: String,
+    pub source: String,
+}
+
+impl CdiSpecDirectory {
+    #[must_use]
+    pub fn new(path: impl Into<String>, source: impl Into<String>) -> Self {
+        Self {
+            path: path.into(),
+            source: source.into(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct CdiDerivedRequirements {
+    pub device_node_paths: Vec<String>,
+    pub read_only_mount_paths: Vec<String>,
+    pub read_write_mount_paths: Vec<String>,
+    pub additional_gids: Vec<u32>,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum CdiError {
+    #[error("CDI policy resolution is unavailable on this platform")]
+    UnsupportedPlatform,
+    #[error("failed to read CDI context '{}': {source}", path.display())]
+    ContextRead {
+        path: PathBuf,
+        source: std::io::Error,
+    },
+    #[error("failed to parse CDI context '{}': {source}", path.display())]
+    ContextParse {
+        path: PathBuf,
+        source: serde_json::Error,
+    },
+    #[error("unsupported CDI context version {0}")]
+    UnsupportedContextVersion(u32),
+    #[error("CDI spec dir '{path}' from source '{diagnostic_source}' is unsafe: {reason}")]
+    UnsafeSpecDir {
+        path: String,
+        diagnostic_source: String,
+        reason: &'static str,
+    },
+    #[error("selected CDI device '{0}' was not found in mounted CDI specs")]
+    MissingDevice(String),
+    #[error(
+        "selected CDI device '{device}' was not found in mounted CDI specs after CDI spec refresh reported: {refresh_error}"
+    )]
+    MissingDeviceAfterRefresh {
+        device: String,
+        refresh_error: String,
+    },
+    #[error("failed to merge CDI edits for '{device}': {error}")]
+    EditMerge { device: String, error: String },
+    #[error("failed to encode resolved CDI edits: {source}")]
+    EditEncode { source: serde_json::Error },
+    #[error("failed to decode resolved CDI edits: {source}")]
+    EditDecode { source: serde_json::Error },
+    #[error("CDI-derived path '{path}' is unsafe: {reason}")]
+    UnsafePolicyPath { path: String, reason: &'static str },
+    #[error("CDI path '{path}' requested conflicting access modes")]
+    ConflictingAccess { path: String },
+    #[error(
+        "CDI writable mount '{path}' is not explicitly listed in the sandbox policy read_write paths"
+    )]
+    WritableMountNotAllowed { path: String },
+    #[error("CDI writable mount '{path}' must target a single file, found {kind}")]
+    WritableMountNotFile { path: String, kind: String },
+    #[error("CDI device node '{path}' must target a character or block device, found {kind}")]
+    DeviceNodeNotDevice { path: String, kind: String },
+    #[error("CDI additionalGids must not contain root GID 0")]
+    RootAdditionalGid,
+    #[error("CDI mount '{path}' has conflicting ro/rw options")]
+    ConflictingMountOptions { path: String },
+}
+
+pub fn read_context(path: impl AsRef<Path>) -> Result<CdiContext, CdiError> {
+    let path = path.as_ref();
+    let json = std::fs::read_to_string(path).map_err(|source| CdiError::ContextRead {
+        path: path.to_path_buf(),
+        source,
+    })?;
+    serde_json::from_str(&json).map_err(|source| CdiError::ContextParse {
+        path: path.to_path_buf(),
+        source,
+    })
+}
+
+#[cfg(target_os = "linux")]
+#[path = "cdi_linux.rs"]
+mod cdi_linux;
+#[cfg(target_os = "linux")]
+pub use cdi_linux::resolve_cdi_context;
+
+#[cfg(not(target_os = "linux"))]
+#[path = "cdi_stub.rs"]
+mod cdi_stub;
+#[cfg(not(target_os = "linux"))]
+pub use cdi_stub::resolve_cdi_context;