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

selinux/
lib.rs
