selinux/
lib.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5pub mod local_cache;
6pub mod permission_check;
7pub mod policy;
8pub mod security_server;
9
10pub use access_vector_cache::{AccessQueryArgs, DEFAULT_SHARED_SIZE, QueryCacheCapacity};
11pub use concurrent_access_cache::{AccessCacheStorage, ConcurrentAccessCache};
12pub use security_server::SecurityServer;
13
14mod access_vector_cache;
15mod cache_stats;
16mod concurrent_access_cache;
17mod concurrent_cache;
18mod exceptions_config;
19mod kernel_permissions;
20mod sid_table;
21mod sync;
22
23/// Allow callers to use the kernel class & permission definitions.
24pub use kernel_permissions::*;
25
26/// Numeric class Ids are provided to the userspace AVC surfaces (e.g. "create", "access", etc).
27pub use policy::ClassId;
28
29pub use starnix_uapi::selinux::{InitialSid, ReferenceInitialSid, SecurityId, TaskAttrs};
30
31use policy::arrays::FsUseType;
32use strum::VariantArray as _;
33use strum_macros::VariantArray;
34
35/// Identifies a specific class by its policy-defined Id, or as a kernel object class enum Id.
36#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
37pub enum ObjectClass {
38    /// Refers to a well-known SELinux kernel object class (e.g. "process", "file", "capability").
39    Kernel(KernelClass),
40    /// Refers to a policy-defined class by its policy-defined numeric Id. This is most commonly
41    /// used when handling queries from userspace, which refer to classes by-Id.
42    ClassId(ClassId),
43}
44
45impl From<ClassId> for ObjectClass {
46    fn from(id: ClassId) -> Self {
47        Self::ClassId(id)
48    }
49}
50
51impl<T: Into<KernelClass>> From<T> for ObjectClass {
52    fn from(class: T) -> Self {
53        Self::Kernel(class.into())
54    }
55}
56
57/// A borrowed byte slice that contains no `NUL` characters by truncating the input slice at the
58/// first `NUL` (if any) upon construction.
59#[derive(Clone, Copy, Debug, PartialEq)]
60pub struct NullessByteStr<'a>(&'a [u8]);
61
62impl<'a> NullessByteStr<'a> {
63    /// Returns a non-null-terminated representation of the security context string.
64    pub fn as_bytes(&self) -> &[u8] {
65        &self.0
66    }
67}
68
69impl<'a, S: AsRef<[u8]> + ?Sized> From<&'a S> for NullessByteStr<'a> {
70    /// Any `AsRef<[u8]>` can be processed into a [`NullessByteStr`]. The [`NullessByteStr`] will
71    /// retain everything up to (but not including) a null character, or else the complete byte
72    /// string.
73    fn from(s: &'a S) -> Self {
74        let value = s.as_ref();
75        match value.iter().position(|c| *c == 0) {
76            Some(end) => Self(&value[..end]),
77            None => Self(value),
78        }
79    }
80}
81
82#[derive(Clone, Debug, PartialEq)]
83pub struct FileSystemMountSids {
84    pub context: Option<SecurityId>,
85    pub fs_context: Option<SecurityId>,
86    pub def_context: Option<SecurityId>,
87    pub root_context: Option<SecurityId>,
88}
89
90#[derive(Clone, Debug, PartialEq)]
91pub struct FileSystemLabel {
92    pub sid: SecurityId,
93    pub scheme: FileSystemLabelingScheme,
94    // Sids obtained by parsing the mount options of the FileSystem.
95    pub mount_sids: FileSystemMountSids,
96}
97
98#[derive(Clone, Debug, PartialEq)]
99pub enum FileSystemLabelingScheme {
100    /// This filesystem was mounted with "context=".
101    Mountpoint { sid: SecurityId },
102    /// This filesystem has an "fs_use_xattr", "fs_use_task", or "fs_use_trans" entry in the
103    /// policy. If the `fs_use_type` is "fs_use_xattr" then the `default_sid` specifies the SID
104    /// with which to label `FsNode`s of files that do not have the "security.selinux" xattr.
105    FsUse { fs_use_type: FsUseType, default_sid: SecurityId },
106    /// This filesystem has one or more "genfscon" statements associated with it in the policy.
107    /// If `supports_seclabel` is true then nodes in the filesystem may be dynamically relabeled.
108    GenFsCon { supports_seclabel: bool },
109}
110
111/// SELinux security context-related filesystem mount options. These options are documented in the
112/// `context=context, fscontext=context, defcontext=context, and rootcontext=context` section of
113/// the `mount(8)` manpage.
114#[derive(Clone, Debug, Default, PartialEq)]
115pub struct FileSystemMountOptions {
116    /// Specifies the effective security context to use for all nodes in the filesystem, and the
117    /// filesystem itself. If the filesystem already contains security attributes then these are
118    /// ignored. May not be combined with any of the other options.
119    pub context: Option<Vec<u8>>,
120    /// Specifies an effective security context to use for un-labeled nodes in the filesystem,
121    /// rather than falling-back to the policy-defined "file" context.
122    pub def_context: Option<Vec<u8>>,
123    /// The value of the `fscontext=[security-context]` mount option. This option is used to
124    /// label the filesystem (superblock) itself.
125    pub fs_context: Option<Vec<u8>>,
126    /// The value of the `rootcontext=[security-context]` mount option. This option is used to
127    /// (re)label the inode located at the filesystem mountpoint.
128    pub root_context: Option<Vec<u8>>,
129}
130
131/// Status information parameter for the [`SeLinuxStatusPublisher`] interface.
132pub struct SeLinuxStatus {
133    /// SELinux-wide enforcing vs. permissive mode  bit.
134    pub is_enforcing: bool,
135    /// Number of times the policy has been changed since SELinux started.
136    pub change_count: u32,
137    /// Bit indicating whether operations unknown SELinux abstractions will be denied.
138    pub deny_unknown: bool,
139}
140
141/// Interface for security server to interact with selinuxfs status file.
142pub trait SeLinuxStatusPublisher: Send + Sync {
143    /// Sets the value part of the associated selinuxfs status file.
144    fn set_status(&mut self, policy_status: SeLinuxStatus);
145}
146
147/// Reference policy capability Ids.
148#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, VariantArray)]
149pub enum PolicyCap {
150    NetworkPeerControls = 0,
151    OpenPerms = 1,
152    ExtendedSocketClass = 2,
153    AlwaysCheckNetwork = 3,
154    CgroupSeclabel = 4,
155    NnpNosuidTransition = 5,
156    GenfsSeclabelSymlinks = 6,
157    IoctlSkipCloexec = 7,
158    UserspaceInitialContext = 8,
159    NetlinkXperm = 9,
160    NetifWildcard = 10,
161    GenfsSeclabelWildcard = 11,
162    FunctionfsSeclabel = 12,
163    MemfdClass = 13,
164}
165
166impl PolicyCap {
167    pub fn name(&self) -> &str {
168        match self {
169            Self::NetworkPeerControls => "network_peer_controls",
170            Self::OpenPerms => "open_perms",
171            Self::ExtendedSocketClass => "extended_socket_class",
172            Self::AlwaysCheckNetwork => "always_check_network",
173            Self::CgroupSeclabel => "cgroup_seclabel",
174            Self::NnpNosuidTransition => "nnp_nosuid_transition",
175            Self::GenfsSeclabelSymlinks => "genfs_seclabel_symlinks",
176            Self::IoctlSkipCloexec => "ioctl_skip_cloexec",
177            Self::UserspaceInitialContext => "userspace_initial_context",
178            Self::NetlinkXperm => "netlink_xperm",
179            Self::NetifWildcard => "netif_wildcard",
180            Self::GenfsSeclabelWildcard => "genfs_seclabel_wildcard",
181            Self::FunctionfsSeclabel => "functionfs_seclabel",
182            Self::MemfdClass => "memfd_class",
183        }
184    }
185
186    pub fn by_name(name: &str) -> Option<Self> {
187        Self::VARIANTS.iter().find(|x| x.name() == name).copied()
188    }
189}
190
191#[cfg(test)]
192mod tests {
193    use super::*;
194    use std::num::NonZeroU32;
195
196    #[test]
197    fn object_class_permissions() {
198        let test_class_id = ClassId::new(NonZeroU32::new(20).unwrap());
199        assert_eq!(ObjectClass::ClassId(test_class_id), test_class_id.into());
200        for variant in ProcessPermission::PERMISSIONS {
201            assert_eq!(KernelClass::Process, variant.class());
202            assert_eq!("process", variant.class().name());
203            assert_eq!(ObjectClass::Kernel(KernelClass::Process), variant.class().into());
204        }
205    }
206
207    #[test]
208    fn policy_capabilities() {
209        for capability in PolicyCap::VARIANTS {
210            assert_eq!(Some(*capability), PolicyCap::by_name(capability.name()));
211        }
212    }
213
214    #[test]
215    fn nulless_byte_str_equivalence() {
216        let unterminated: NullessByteStr<'_> = b"u:object_r:test_valid_t:s0".into();
217        let nul_terminated: NullessByteStr<'_> = b"u:object_r:test_valid_t:s0\0".into();
218        let nul_containing: NullessByteStr<'_> =
219            b"u:object_r:test_valid_t:s0\0IGNORE THIS\0!\0".into();
220
221        for context in [nul_terminated, nul_containing] {
222            assert_eq!(unterminated, context);
223            assert_eq!(unterminated.as_bytes(), context.as_bytes());
224        }
225    }
226}
selinux/lib.rs

selinux/
lib.rs
