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

selinux/
lib.rs
