starnix_uapi/
auth.rs

1// Copyright 2023 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
5#![allow(dead_code)]
6
7use crate::errors::{Errno, error};
8use crate::selinux::TaskAttrs;
9use crate::{gid_t, uapi, uid_t};
10use bitflags::bitflags;
11use std::sync::{Arc, LazyLock};
12
13bitflags! {
14    /// Linux capability flags for thread permission checks and bounding sets.
15    ///
16    /// Handles only known and valid Linux capabilities (bits `0` through
17    /// [`CAP_LAST_CAP`]). Any undefined capability bits in raw masks from user space
18    /// are truncated during ABI conversion using [`Self::from_bits_truncate`].
19    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
20    pub struct Capabilities: u64 {
21        // keep-sorted start
22        const AUDIT_CONTROL = 1 << uapi::CAP_AUDIT_CONTROL;
23        const AUDIT_READ = 1 << uapi::CAP_AUDIT_READ;
24        const AUDIT_WRITE = 1 << uapi::CAP_AUDIT_WRITE;
25        const BLOCK_SUSPEND = 1 << uapi::CAP_BLOCK_SUSPEND;
26        const BPF = 1 << uapi::CAP_BPF;
27        const CHECKPOINT_RESTORE = 1 << uapi::CAP_CHECKPOINT_RESTORE;
28        const CHOWN = 1 << uapi::CAP_CHOWN;
29        const DAC_OVERRIDE = 1 << uapi::CAP_DAC_OVERRIDE;
30        const DAC_READ_SEARCH = 1 << uapi::CAP_DAC_READ_SEARCH;
31        const FOWNER = 1 << uapi::CAP_FOWNER;
32        const FSETID = 1 << uapi::CAP_FSETID;
33        const IPC_LOCK = 1 << uapi::CAP_IPC_LOCK;
34        const IPC_OWNER = 1 << uapi::CAP_IPC_OWNER;
35        const KILL = 1 << uapi::CAP_KILL;
36        const LEASE = 1 << uapi::CAP_LEASE;
37        const LINUX_IMMUTABLE = 1 << uapi::CAP_LINUX_IMMUTABLE;
38        const MAC_ADMIN = 1 << uapi::CAP_MAC_ADMIN;
39        const MAC_OVERRIDE = 1 << uapi::CAP_MAC_OVERRIDE;
40        const MKNOD = 1 << uapi::CAP_MKNOD;
41        const NET_ADMIN = 1 << uapi::CAP_NET_ADMIN;
42        const NET_BIND_SERVICE = 1 << uapi::CAP_NET_BIND_SERVICE;
43        const NET_BROADCAST = 1 << uapi::CAP_NET_BROADCAST;
44        const NET_RAW = 1 << uapi::CAP_NET_RAW;
45        const PERFMON = 1 << uapi::CAP_PERFMON;
46        const SETFCAP = 1 << uapi::CAP_SETFCAP;
47        const SETGID = 1 << uapi::CAP_SETGID;
48        const SETPCAP = 1 << uapi::CAP_SETPCAP;
49        const SETUID = 1 << uapi::CAP_SETUID;
50        const SYSLOG = 1 << uapi::CAP_SYSLOG;
51        const SYS_ADMIN = 1 << uapi::CAP_SYS_ADMIN;
52        const SYS_BOOT = 1 << uapi::CAP_SYS_BOOT;
53        const SYS_CHROOT = 1 << uapi::CAP_SYS_CHROOT;
54        const SYS_MODULE = 1 << uapi::CAP_SYS_MODULE;
55        const SYS_NICE = 1 << uapi::CAP_SYS_NICE;
56        const SYS_PACCT = 1 << uapi::CAP_SYS_PACCT;
57        const SYS_PTRACE = 1 << uapi::CAP_SYS_PTRACE;
58        const SYS_RAWIO = 1 << uapi::CAP_SYS_RAWIO;
59        const SYS_RESOURCE = 1 << uapi::CAP_SYS_RESOURCE;
60        const SYS_TIME = 1 << uapi::CAP_SYS_TIME;
61        const SYS_TTY_CONFIG = 1 << uapi::CAP_SYS_TTY_CONFIG;
62        const WAKE_ALARM = 1 << uapi::CAP_WAKE_ALARM;
63        // keep-sorted end
64    }
65}
66
67impl Capabilities {
68    pub const fn as_abi_v1(self) -> u32 {
69        self.bits() as u32
70    }
71
72    pub fn from_abi_v1(bits: u32) -> Self {
73        Self::from_bits_truncate(bits as u64)
74    }
75
76    pub const fn as_abi_v3(self) -> (u32, u32) {
77        (self.bits() as u32, (self.bits() >> 32) as u32)
78    }
79
80    pub fn from_abi_v3(u32s: (u32, u32)) -> Self {
81        let mask = u32s.0 as u64 | ((u32s.1 as u64) << 32);
82        Self::from_bits_truncate(mask)
83    }
84}
85
86impl std::convert::TryFrom<u64> for Capabilities {
87    type Error = Errno;
88
89    fn try_from(capability_num: u64) -> Result<Self, Self::Error> {
90        match 1u64.checked_shl(capability_num as u32) {
91            Some(mask) => {
92                let caps = Self::from_bits_truncate(mask);
93                if caps.is_empty() { error!(EINVAL) } else { Ok(caps) }
94            }
95            _ => error!(EINVAL),
96        }
97    }
98}
99
100impl std::str::FromStr for Capabilities {
101    type Err = Errno;
102    fn from_str(s: &str) -> Result<Self, Self::Err> {
103        Ok(match s {
104            // keep-sorted start
105            "AUDIT_CONTROL" => Self::AUDIT_CONTROL,
106            "AUDIT_READ" => Self::AUDIT_READ,
107            "AUDIT_WRITE" => Self::AUDIT_WRITE,
108            "BLOCK_SUSPEND" => Self::BLOCK_SUSPEND,
109            "BPF" => Self::BPF,
110            "CHECKPOINT_RESTORE" => Self::CHECKPOINT_RESTORE,
111            "CHOWN" => Self::CHOWN,
112            "DAC_OVERRIDE" => Self::DAC_OVERRIDE,
113            "DAC_READ_SEARCH" => Self::DAC_READ_SEARCH,
114            "FOWNER" => Self::FOWNER,
115            "FSETID" => Self::FSETID,
116            "IPC_LOCK" => Self::IPC_LOCK,
117            "IPC_OWNER" => Self::IPC_OWNER,
118            "KILL" => Self::KILL,
119            "LEASE" => Self::LEASE,
120            "LINUX_IMMUTABLE" => Self::LINUX_IMMUTABLE,
121            "MAC_ADMIN" => Self::MAC_ADMIN,
122            "MAC_OVERRIDE" => Self::MAC_OVERRIDE,
123            "MKNOD" => Self::MKNOD,
124            "NET_ADMIN" => Self::NET_ADMIN,
125            "NET_BIND_SERVICE" => Self::NET_BIND_SERVICE,
126            "NET_BROADCAST" => Self::NET_BROADCAST,
127            "NET_RAW" => Self::NET_RAW,
128            "PERFMON" => Self::PERFMON,
129            "SETFCAP" => Self::SETFCAP,
130            "SETGID" => Self::SETGID,
131            "SETPCAP" => Self::SETPCAP,
132            "SETUID" => Self::SETUID,
133            "SYSLOG" => Self::SYSLOG,
134            "SYS_ADMIN" => Self::SYS_ADMIN,
135            "SYS_BOOT" => Self::SYS_BOOT,
136            "SYS_CHROOT" => Self::SYS_CHROOT,
137            "SYS_MODULE" => Self::SYS_MODULE,
138            "SYS_NICE" => Self::SYS_NICE,
139            "SYS_PACCT" => Self::SYS_PACCT,
140            "SYS_PTRACE" => Self::SYS_PTRACE,
141            "SYS_RAWIO" => Self::SYS_RAWIO,
142            "SYS_RESOURCE" => Self::SYS_RESOURCE,
143            "SYS_TIME" => Self::SYS_TIME,
144            "SYS_TTY_CONFIG" => Self::SYS_TTY_CONFIG,
145            "WAKE_ALARM" => Self::WAKE_ALARM,
146            // keep-sorted end
147            _ => return error!(EINVAL),
148        })
149    }
150}
151
152// keep-sorted start
153pub const CAP_AUDIT_CONTROL: Capabilities = Capabilities::AUDIT_CONTROL;
154pub const CAP_AUDIT_READ: Capabilities = Capabilities::AUDIT_READ;
155pub const CAP_AUDIT_WRITE: Capabilities = Capabilities::AUDIT_WRITE;
156pub const CAP_BLOCK_SUSPEND: Capabilities = Capabilities::BLOCK_SUSPEND;
157pub const CAP_BPF: Capabilities = Capabilities::BPF;
158pub const CAP_CHECKPOINT_RESTORE: Capabilities = Capabilities::CHECKPOINT_RESTORE;
159pub const CAP_CHOWN: Capabilities = Capabilities::CHOWN;
160pub const CAP_DAC_OVERRIDE: Capabilities = Capabilities::DAC_OVERRIDE;
161pub const CAP_DAC_READ_SEARCH: Capabilities = Capabilities::DAC_READ_SEARCH;
162pub const CAP_FOWNER: Capabilities = Capabilities::FOWNER;
163pub const CAP_FSETID: Capabilities = Capabilities::FSETID;
164pub const CAP_IPC_LOCK: Capabilities = Capabilities::IPC_LOCK;
165pub const CAP_IPC_OWNER: Capabilities = Capabilities::IPC_OWNER;
166pub const CAP_KILL: Capabilities = Capabilities::KILL;
167pub const CAP_LEASE: Capabilities = Capabilities::LEASE;
168pub const CAP_LINUX_IMMUTABLE: Capabilities = Capabilities::LINUX_IMMUTABLE;
169pub const CAP_MAC_ADMIN: Capabilities = Capabilities::MAC_ADMIN;
170pub const CAP_MAC_OVERRIDE: Capabilities = Capabilities::MAC_OVERRIDE;
171pub const CAP_MKNOD: Capabilities = Capabilities::MKNOD;
172pub const CAP_NET_ADMIN: Capabilities = Capabilities::NET_ADMIN;
173pub const CAP_NET_BIND_SERVICE: Capabilities = Capabilities::NET_BIND_SERVICE;
174pub const CAP_NET_BROADCAST: Capabilities = Capabilities::NET_BROADCAST;
175pub const CAP_NET_RAW: Capabilities = Capabilities::NET_RAW;
176pub const CAP_PERFMON: Capabilities = Capabilities::PERFMON;
177pub const CAP_SETFCAP: Capabilities = Capabilities::SETFCAP;
178pub const CAP_SETGID: Capabilities = Capabilities::SETGID;
179pub const CAP_SETPCAP: Capabilities = Capabilities::SETPCAP;
180pub const CAP_SETUID: Capabilities = Capabilities::SETUID;
181pub const CAP_SYSLOG: Capabilities = Capabilities::SYSLOG;
182pub const CAP_SYS_ADMIN: Capabilities = Capabilities::SYS_ADMIN;
183pub const CAP_SYS_BOOT: Capabilities = Capabilities::SYS_BOOT;
184pub const CAP_SYS_CHROOT: Capabilities = Capabilities::SYS_CHROOT;
185pub const CAP_SYS_MODULE: Capabilities = Capabilities::SYS_MODULE;
186pub const CAP_SYS_NICE: Capabilities = Capabilities::SYS_NICE;
187pub const CAP_SYS_PACCT: Capabilities = Capabilities::SYS_PACCT;
188pub const CAP_SYS_PTRACE: Capabilities = Capabilities::SYS_PTRACE;
189pub const CAP_SYS_RAWIO: Capabilities = Capabilities::SYS_RAWIO;
190pub const CAP_SYS_RESOURCE: Capabilities = Capabilities::SYS_RESOURCE;
191pub const CAP_SYS_TIME: Capabilities = Capabilities::SYS_TIME;
192pub const CAP_SYS_TTY_CONFIG: Capabilities = Capabilities::SYS_TTY_CONFIG;
193pub const CAP_WAKE_ALARM: Capabilities = Capabilities::WAKE_ALARM;
194// keep-sorted end
195pub const CAP_LAST_CAP: u32 = uapi::CAP_LAST_CAP;
196
197bitflags! {
198    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
199    pub struct PtraceAccessMode: u32 {
200        const READ      = 1 << 0;
201        const ATTACH    = 1 << 1;
202        const FSCREDS   = 1 << 2;
203        const REALCREDS = 1 << 3;
204        const NOAUDIT   = 1 << 4;
205    }
206}
207
208pub const PTRACE_MODE_READ: PtraceAccessMode = PtraceAccessMode::READ;
209pub const PTRACE_MODE_ATTACH: PtraceAccessMode = PtraceAccessMode::ATTACH;
210pub const PTRACE_MODE_FSCREDS: PtraceAccessMode = PtraceAccessMode::FSCREDS;
211pub const PTRACE_MODE_REALCREDS: PtraceAccessMode = PtraceAccessMode::REALCREDS;
212pub const PTRACE_MODE_READ_FSCREDS: PtraceAccessMode = PtraceAccessMode::from_bits_truncate(
213    PtraceAccessMode::READ.bits() | PtraceAccessMode::FSCREDS.bits(),
214);
215pub const PTRACE_MODE_READ_REALCREDS: PtraceAccessMode = PtraceAccessMode::from_bits_truncate(
216    PtraceAccessMode::READ.bits() | PtraceAccessMode::REALCREDS.bits(),
217);
218pub const PTRACE_MODE_ATTACH_FSCREDS: PtraceAccessMode = PtraceAccessMode::from_bits_truncate(
219    PtraceAccessMode::ATTACH.bits() | PtraceAccessMode::FSCREDS.bits(),
220);
221pub const PTRACE_MODE_ATTACH_REALCREDS: PtraceAccessMode = PtraceAccessMode::from_bits_truncate(
222    PtraceAccessMode::ATTACH.bits() | PtraceAccessMode::REALCREDS.bits(),
223);
224pub const PTRACE_MODE_NOAUDIT: PtraceAccessMode = PtraceAccessMode::NOAUDIT;
225
226#[derive(Debug, Clone)]
227pub struct Credentials {
228    pub uid: uid_t,
229    pub gid: gid_t,
230    pub euid: uid_t,
231    pub egid: gid_t,
232    pub saved_uid: uid_t,
233    pub saved_gid: gid_t,
234    pub groups: Vec<gid_t>,
235
236    /// See https://man7.org/linux/man-pages/man2/setfsuid.2.html
237    pub fsuid: uid_t,
238
239    /// See https://man7.org/linux/man-pages/man2/setfsgid.2.html
240    pub fsgid: gid_t,
241
242    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
243    ///
244    /// > This is a limiting superset for the effective capabilities that the thread may assume. It
245    /// > is also a limiting superset for the capabilities that may be added to the inheritable set
246    /// > by a thread that does not have the CAP_SETPCAP capability in its effective set.
247    ///
248    /// > If a thread drops a capability from its permitted set, it can never reacquire that
249    /// > capability (unless it execve(2)s either a set-user-ID-root program, or a program whose
250    /// > associated file capabilities grant that capability).
251    pub cap_permitted: Capabilities,
252
253    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
254    ///
255    /// > This is the set of capabilities used by the kernel to perform permission checks for the
256    /// > thread.
257    pub cap_effective: Capabilities,
258
259    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
260    ///
261    /// > This is a set of capabilities preserved across an execve(2).  Inheritable capabilities
262    /// > remain inheritable when executing any program, and inheritable capabilities are added to
263    /// > the permitted set when executing a program that has the corresponding bits set in the file
264    /// > inheritable set.
265    ///
266    /// > Because inheritable capabilities are not generally preserved across execve(2) when running
267    /// > as a non-root user, applications that wish to run helper programs with elevated
268    /// > capabilities should consider using ambient capabilities, described below.
269    pub cap_inheritable: Capabilities,
270
271    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
272    ///
273    /// > The capability bounding set is a mechanism that can be used to limit the capabilities that
274    /// > are gained during execve(2).
275    ///
276    /// > Since Linux 2.6.25, this is a per-thread capability set. In older kernels, the capability
277    /// > bounding set was a system wide attribute shared by all threads on the system.
278    pub cap_bounding: Capabilities,
279
280    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
281    ///
282    /// > This is a set of capabilities that are preserved across an execve(2) of a program that is
283    /// > not privileged.  The ambient capability set obeys the invariant that no capability can
284    /// > ever be ambient if it is not both permitted and inheritable.
285    ///
286    /// > Executing a program that changes UID or GID due to the set-user-ID or set-group-ID bits
287    /// > or executing a program that has any file capabilities set will clear the ambient set.
288    pub cap_ambient: Capabilities,
289
290    /// From https://man7.org/linux/man-pages/man7/capabilities.7.html
291    ///
292    /// > Starting with kernel 2.6.26, and with a kernel in which file capabilities are enabled,
293    /// > Linux implements a set of per-thread securebits flags that can be used to disable special
294    /// > handling of capabilities for UID 0 (root).
295    ///
296    /// > The securebits flags can be modified and retrieved using the prctl(2)
297    /// > PR_SET_SECUREBITS and PR_GET_SECUREBITS operations.  The CAP_SETPCAP capability is
298    /// > required to modify the flags.
299    pub securebits: SecureBits,
300
301    /// The SELinux security state of the task.
302    pub security_state: TaskAttrs,
303}
304
305bitflags! {
306    #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
307    pub struct SecureBits: u32 {
308        const KEEP_CAPS = 1 << uapi::SECURE_KEEP_CAPS;
309        const KEEP_CAPS_LOCKED = 1 <<  uapi::SECURE_KEEP_CAPS_LOCKED;
310        const NO_SETUID_FIXUP = 1 << uapi::SECURE_NO_SETUID_FIXUP;
311        const NO_SETUID_FIXUP_LOCKED = 1 << uapi::SECURE_NO_SETUID_FIXUP_LOCKED;
312        const NOROOT = 1 << uapi::SECURE_NOROOT;
313        const NOROOT_LOCKED = 1 << uapi::SECURE_NOROOT_LOCKED;
314        const NO_CAP_AMBIENT_RAISE = 1 << uapi::SECURE_NO_CAP_AMBIENT_RAISE;
315        const NO_CAP_AMBIENT_RAISE_LOCKED = 1 << uapi::SECURE_NO_CAP_AMBIENT_RAISE_LOCKED;
316    }
317}
318
319static ROOT_CREDENTIALS: LazyLock<Arc<Credentials>> =
320    LazyLock::new(|| Arc::new(Credentials::with_ids(0, 0)));
321
322impl Credentials {
323    /// Creates a set of credentials with all possible permissions and capabilities.
324    pub fn root() -> Arc<Self> {
325        ROOT_CREDENTIALS.clone()
326    }
327
328    /// Creates a set of credentials with the given uid and gid. If the uid is 0, the credentials
329    /// will grant superuser access.
330    pub fn with_ids(uid: uid_t, gid: gid_t) -> Credentials {
331        let caps = if uid == 0 { Capabilities::all() } else { Capabilities::empty() };
332        Credentials {
333            uid,
334            gid,
335            euid: uid,
336            egid: gid,
337            saved_uid: uid,
338            saved_gid: gid,
339            groups: vec![],
340            fsuid: uid,
341            fsgid: gid,
342            cap_permitted: caps,
343            cap_effective: caps,
344            cap_inheritable: Capabilities::empty(),
345            cap_bounding: Capabilities::all(),
346            cap_ambient: Capabilities::empty(),
347            securebits: SecureBits::empty(),
348            security_state: TaskAttrs::for_kernel(),
349        }
350    }
351
352    pub fn is_in_group(&self, gid: gid_t) -> bool {
353        self.egid == gid || self.groups.contains(&gid)
354    }
355
356    /// Updates the `securebits` field, taking into account *`_LOCKED` bits.
357    pub fn set_securebits(&mut self, securebits: SecureBits) -> Result<(), Errno> {
358        // If a lock bit is set then neither it nor the corresponding `SECBIT_*` can be changed.
359        let mut locked_bits = SecureBits::empty();
360        if self.securebits.contains(SecureBits::NOROOT_LOCKED) {
361            locked_bits |= SecureBits::NOROOT | SecureBits::NOROOT_LOCKED;
362        }
363        if self.securebits.contains(SecureBits::KEEP_CAPS_LOCKED) {
364            locked_bits |= SecureBits::KEEP_CAPS | SecureBits::KEEP_CAPS_LOCKED;
365        }
366        if self.securebits.contains(SecureBits::NO_SETUID_FIXUP_LOCKED) {
367            locked_bits |= SecureBits::NO_SETUID_FIXUP | SecureBits::NO_SETUID_FIXUP_LOCKED;
368        }
369        if self.securebits.contains(SecureBits::NO_CAP_AMBIENT_RAISE_LOCKED) {
370            locked_bits |=
371                SecureBits::NO_CAP_AMBIENT_RAISE | SecureBits::NO_CAP_AMBIENT_RAISE_LOCKED;
372        }
373
374        if securebits & locked_bits != self.securebits & locked_bits {
375            return error!(EPERM);
376        }
377
378        self.securebits = securebits;
379        Ok(())
380    }
381
382    pub fn as_fscred(&self) -> FsCred {
383        FsCred { uid: self.fsuid, gid: self.fsgid }
384    }
385
386    pub fn euid_as_fscred(&self) -> FsCred {
387        FsCred { uid: self.euid, gid: self.egid }
388    }
389
390    pub fn uid_as_fscred(&self) -> FsCred {
391        FsCred { uid: self.uid, gid: self.gid }
392    }
393
394    /// Adjusts the capability sets (permitted, effective, and ambient) of these credentials
395    /// to reflect changes in user IDs (UID, EUID, Saved UID, or FSUID) from a previous state.
396    ///
397    /// This method compares the current state of these credentials against the `prev`
398    /// credentials to implement the Linux security model rules for UID transitions (as described
399    /// in `capabilities(7)` under "Effect of user ID changes on capabilities"). It is typically
400    /// called when preparing a new set of `Credentials` during `setuid()` family syscalls or
401    /// during `exec` after UID/GID bits have been applied.
402    pub fn update_capabilities(&mut self, prev: &Credentials) {
403        // https://man7.org/linux/man-pages/man7/capabilities.7.html
404        // If one or more of the real, effective, or saved set user IDs
405        // was previously 0, and as a result of the UID changes all of
406        // these IDs have a nonzero value, then all capabilities are
407        // cleared from the permitted, effective, and ambient capability
408        // sets.
409        //
410        // SECBIT_KEEP_CAPS: Setting this flag allows a thread that has one or more 0
411        // UIDs to retain capabilities in its permitted set when it
412        // switches all of its UIDs to nonzero values.
413        // The setting of the SECBIT_KEEP_CAPS flag is ignored if the
414        // SECBIT_NO_SETUID_FIXUP flag is set.  (The latter flag
415        // provides a superset of the effect of the former flag.)
416        // SECBIT_NO_SETUID_FIXUP: Setting  this  flag  stops  the  kernel from adjusting
417        // the process's permitted, effective, and ambient capability sets when the thread's
418        // effective and filesystem UIDs are switched between zero and nonzero values.
419        if self.securebits.contains(SecureBits::NO_SETUID_FIXUP) {
420            return;
421        }
422        let was_any_zero = prev.uid == 0 || prev.euid == 0 || prev.saved_uid == 0;
423        let is_all_nonzero = self.uid != 0 && self.euid != 0 && self.saved_uid != 0;
424
425        if was_any_zero && is_all_nonzero {
426            if !self.securebits.contains(SecureBits::KEEP_CAPS) {
427                self.cap_permitted = Capabilities::empty();
428                self.cap_effective = Capabilities::empty();
429            }
430            self.cap_ambient = Capabilities::empty();
431        }
432        // If the effective user ID is changed from 0 to nonzero, then
433        // all capabilities are cleared from the effective set.
434        if prev.euid == 0 && self.euid != 0 {
435            self.cap_effective = Capabilities::empty();
436        } else if prev.euid != 0 && self.euid == 0 {
437            // If the effective user ID is changed from nonzero to 0, then
438            // the permitted set is copied to the effective set.
439            self.cap_effective = self.cap_permitted;
440        }
441
442        // If the filesystem user ID is changed from 0 to nonzero (see
443        // setfsuid(2)), then the following capabilities are cleared from
444        // the effective set: CAP_CHOWN, CAP_DAC_OVERRIDE,
445        // CAP_DAC_READ_SEARCH, CAP_FOWNER, CAP_FSETID,
446        // CAP_LINUX_IMMUTABLE (since Linux 2.6.30), CAP_MAC_OVERRIDE,
447        // and CAP_MKNOD (since Linux 2.6.30).
448        let fs_capabilities = CAP_CHOWN
449            | CAP_DAC_OVERRIDE
450            | CAP_DAC_READ_SEARCH
451            | CAP_FOWNER
452            | CAP_FSETID
453            | CAP_LINUX_IMMUTABLE
454            | CAP_MAC_OVERRIDE
455            | CAP_MKNOD;
456        if prev.fsuid == 0 && self.fsuid != 0 {
457            self.cap_effective &= !fs_capabilities;
458        } else if prev.fsuid != 0 && self.fsuid == 0 {
459            // If the filesystem UID is changed from nonzero to 0, then any
460            // of these capabilities that are enabled in the permitted set
461            // are enabled in the effective set.
462            self.cap_effective |= self.cap_permitted & fs_capabilities;
463        }
464    }
465}
466
467/// The owner and group of a file. Used as a parameter for functions that create files.
468#[derive(Debug, Clone, Copy)]
469pub struct FsCred {
470    pub uid: uid_t,
471    pub gid: gid_t,
472}
473
474impl FsCred {
475    pub const fn root() -> Self {
476        Self { uid: 0, gid: 0 }
477    }
478}
479
480impl From<Credentials> for FsCred {
481    fn from(c: Credentials) -> Self {
482        c.as_fscred()
483    }
484}
485
486#[derive(Debug, Default, Clone)]
487pub struct UserAndOrGroupId {
488    pub uid: Option<uid_t>,
489    pub gid: Option<gid_t>,
490}
491
492impl UserAndOrGroupId {
493    pub fn is_none(&self) -> bool {
494        self.uid.is_none() && self.gid.is_none()
495    }
496
497    pub fn is_some(&self) -> bool {
498        !self.is_none()
499    }
500
501    pub fn clear(&mut self) {
502        self.uid = None;
503        self.gid = None;
504    }
505}
506
507#[cfg(test)]
508mod tests {
509    use super::*;
510
511    #[::fuchsia::test]
512    fn test_empty() {
513        assert_eq!(Capabilities::empty().bits(), 0);
514    }
515
516    #[::fuchsia::test]
517    fn test_union() {
518        let expected = CAP_BLOCK_SUSPEND | CAP_AUDIT_READ;
519        assert_eq!(CAP_BLOCK_SUSPEND.union(CAP_AUDIT_READ), expected);
520        assert_eq!(CAP_BLOCK_SUSPEND.union(CAP_BLOCK_SUSPEND), CAP_BLOCK_SUSPEND);
521    }
522
523    #[::fuchsia::test]
524    fn test_difference() {
525        let base = CAP_BPF | CAP_AUDIT_WRITE;
526        let expected = CAP_BPF;
527        assert_eq!(base.difference(CAP_AUDIT_WRITE), expected);
528        assert_eq!(base.difference(CAP_AUDIT_WRITE | CAP_BPF), Capabilities::empty());
529    }
530
531    #[::fuchsia::test]
532    fn test_contains() {
533        let base = CAP_BPF | CAP_AUDIT_WRITE;
534        assert!(base.contains(CAP_AUDIT_WRITE));
535        assert!(base.contains(CAP_BPF));
536        assert!(base.contains(CAP_AUDIT_WRITE | CAP_BPF));
537
538        assert!(!base.contains(CAP_AUDIT_CONTROL));
539        assert!(!base.contains(CAP_AUDIT_WRITE | CAP_BPF | CAP_AUDIT_CONTROL));
540    }
541
542    #[::fuchsia::test]
543    fn test_insert() {
544        let mut capabilities = CAP_BLOCK_SUSPEND;
545        capabilities.insert(CAP_BLOCK_SUSPEND);
546        assert_eq!(capabilities, CAP_BLOCK_SUSPEND);
547
548        capabilities.insert(CAP_AUDIT_READ);
549        let expected = CAP_BLOCK_SUSPEND | CAP_AUDIT_READ;
550        assert_eq!(capabilities, expected);
551    }
552
553    #[::fuchsia::test]
554    fn test_remove() {
555        let mut capabilities = CAP_BLOCK_SUSPEND;
556        capabilities.remove(CAP_BLOCK_SUSPEND);
557        assert_eq!(capabilities, Capabilities::empty());
558
559        let mut capabilities = CAP_BLOCK_SUSPEND | CAP_AUDIT_READ;
560        capabilities.remove(CAP_AUDIT_READ);
561        assert_eq!(capabilities, CAP_BLOCK_SUSPEND);
562    }
563
564    #[::fuchsia::test]
565    fn test_try_from() {
566        let capabilities = CAP_BLOCK_SUSPEND;
567        assert_eq!(Capabilities::try_from(uapi::CAP_BLOCK_SUSPEND as u64), Ok(capabilities));
568
569        assert_eq!(Capabilities::try_from(200000), error!(EINVAL));
570    }
571}
starnix_uapi/auth.rs

starnix_uapi/
auth.rs
