vasilito
e51eecf458
Fixed stale references to COMPREHENSIVE-OS-ASSESSMENT, DESKTOP-STACK, QT6-PORT in subsystem plans. All now point to CONSOLE-TO-KDE v4.0.
749 lines
32 KiB
Markdown
749 lines
32 KiB
Markdown
# Red Bear OS — Kernel, IPC, and Credential Syscalls Plan
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**Date:** 2026-04-30
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**Scope:** Kernel architecture, IPC infrastructure, credential syscalls, process isolation
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**Implementation status:** Phases K1-K2, K4 ✅ complete. Phases K3, K5 deferred.
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**Status:** This document is the canonical kernel + IPC plan, extending `local/docs/COMPREHENSIVE-OS-ASSESSMENT.md`
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## 1. Purpose
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This plan defines the implementation roadmap for kernel hardening, IPC improvements, and credential
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syscall implementation in Red Bear OS. It is the **canonical kernel authority** superseding scattered
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kernel guidance in other docs.
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**Relationship to existing plans:**
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| Document | Relationship |
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|----------|-------------|
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| `CONSOLE-TO-KDE-DESKTOP-PLAN.md` | Parent: CONSOLE-TO-KDE v4.0 (Kernel & Core Infrastructure) |
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| `IRQ-AND-LOWLEVEL-CONTROLLERS-ENHANCEMENT-PLAN.md` | Sibling: IRQ/PCI/MSI-X — not duplicated here |
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| `RELIBC-IPC-ASSESSMENT-AND-IMPROVEMENT-PLAN.md` | Companion: relibc IPC surface — this plan covers kernel side |
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| `ACPI-IMPROVEMENT-PLAN.md` | Sibling: ACPI power/shutdown — relevant for §4 (shutdown robustness) |
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| `CONSOLE-TO-KDE-DESKTOP-PLAN.md` | Consumer: desktop stack depends on kernel work here |
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## 2. Current Architecture Assessment
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### 2.1 Kernel Overview
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The Redox microkernel (`recipes/core/kernel/source/`) is a ~20-40k LoC Rust microkernel. It runs in
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ring 0 and provides:
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- **12 kernel schemes**: `debug`, `event`, `memory`, `pipe`, `irq`, `time`, `sys`, `proc`, `serio`,
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`acpi`, `dtb`, `user` (userspace scheme wrapper)
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- **~35 handled syscalls**: file I/O, memory mapping, process control, futex, time
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- **Catch-all ENOSYS**: all unhandled syscall numbers return `ENOSYS`
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```
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recipes/core/kernel/source/src/
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├── syscall/ # Syscall dispatch: mod.rs (handlers), fs.rs, process.rs, futex.rs, time.rs
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│ └── mod.rs # Main syscall() dispatch: 35 explicit match arms, _ => ENOSYS
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├── scheme/ # Kernel schemes: debug, event, memory, pipe, irq, time, sys, proc, serio
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│ ├── mod.rs # Scheme trait definition, SchemeId, FileHandle types
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│ ├── proc.rs # Process manager scheme (fork, exec, signal, credential setting)
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│ └── sys/ # System info scheme: context list, syscall debug, uname
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├── context/ # Process/thread context management
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│ ├── context.rs # Context struct: euid, egid, pid, files, signals, addr_space
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│ └── memory.rs # Address space, grants, mmap implementation
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├── memory/ # Physical/virtual memory management, page tables
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└── sync/ # Locking primitives (RwLock, Mutex, CleanLockToken)
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```
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### 2.2 Syscall Dispatch Architecture
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The kernel's `syscall()` function in `syscall/mod.rs` dispatches based on `a` (syscall number):
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```rust
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// From recipes/core/kernel/source/src/syscall/mod.rs (line 75)
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match a {
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SYS_WRITE2 => file_op_generic_ext(..),
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SYS_WRITE => sys_write(..),
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SYS_FMAP => { .. }, // Anonymous or file-backed mmap
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SYS_READ2 => file_op_generic_ext(..),
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SYS_READ => sys_read(..),
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SYS_FPATH => file_op_generic(..),
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SYS_FSTAT => fstat(..),
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SYS_DUP => dup(..),
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SYS_DUP2 => dup2(..),
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SYS_SENDFD => sendfd(..),
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SYS_OPENAT => openat(..),
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SYS_UNLINKAT => unlinkat(..),
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SYS_CLOSE => close(..),
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SYS_CALL => call(..), // Scheme IPC: send message to scheme
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SYS_FEVENT => fevent(..), // Register event on fd
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SYS_YIELD => sched_yield(..),
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SYS_NANOSLEEP => nanosleep(..),
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SYS_CLOCK_GETTIME => clock_gettime(..),
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SYS_FUTEX => futex(..),
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SYS_MPROTECT => mprotect(..),
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SYS_MREMAP => mremap(..),
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// ... ~15 more file operations (fchmod, fchown, fcntl, flink, frename, ftruncate, fsync, etc.)
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_ => Err(Error::new(ENOSYS)), // ← CATCH-ALL: all credential syscalls fall here
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}
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```
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Syscall numbers come from the external `redox_syscall` crate (crates.io), not from the kernel tree.
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The kernel consumes them via `use syscall::number::*`.
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### 2.3 Credential Architecture (Current)
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**Kernel Context struct** (`context/context.rs`):
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```rust
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pub struct Context {
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// Credential fields (initialized to 0):
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pub euid: u32, // Effective user ID — used for scheme access control
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pub egid: u32, // Effective group ID
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pub pid: usize, // Process ID (set via proc scheme)
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// NOT present in kernel:
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// ruid, suid — real/saved UID (maintained in userspace redox-rt)
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// rgid, sgid — real/saved GID (maintained in userspace redox-rt)
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// supplementary groups — not implemented anywhere
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// Access control interface:
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pub fn caller_ctx(&self) -> CallerCtx {
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CallerCtx { uid: self.euid, gid: self.egid, pid: self.pid }
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}
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}
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```
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**Credential read path** (userspace, no kernel involvement):
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```
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getuid() → relibc::platform::redox::getuid()
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→ redox_rt::sys::posix_getresugid()
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→ reads local DYNAMIC_PROC_INFO { ruid, euid, suid, rgid, egid, sgid }
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→ returns cached userspace values (NO kernel syscall)
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```
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**Credential write path** (through `proc:` scheme):
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```
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setresuid(ruid, euid, suid) → relibc::platform::redox::setresuid()
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→ redox_rt::sys::posix_setresugid(&Resugid { ruid, euid, suid, .. })
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→ packs 6×u32 into buffer
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→ this_proc_call(&buf, CallFlags::empty(), &[ProcCall::SetResugid as u64])
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→ SYS_CALL to proc: scheme
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→ kernel proc scheme handler (scheme/proc.rs:1269):
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guard.euid = info.euid;
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guard.egid = info.egid;
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```
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**Key finding**: The kernel DOES support credential setting through the `proc:` scheme, using
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`ProcSchemeAttrs` with `euid`/`egid`/`pid`/`prio`/`debug_name` fields. The `getuid()`/`getgid()`
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functions work through userspace-cached values in `redox-rt`. `setresuid()`/`setresgid()` work
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through the proc scheme.
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**What's genuinely broken:**
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| Function | Status | Root Cause |
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|----------|--------|------------|
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| `setgroups()` | **ENOSYS stub** | relibc/redox/mod.rs:1205 — `todo_skip!(0, "setgroups({}, {:p}): not implemented")` |
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| `getgroups()` | /etc/group-based | Works via `getpwuid()` + `getgrent()` iteration — doesn't use kernel groups |
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| `initgroups()` | No-op | No supplementary group infrastructure |
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### 2.4 IPC Architecture
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**Scheme-based IPC** is the primary IPC mechanism:
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```
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┌─────────────┐ SYS_CALL(syscall) ┌──────────────┐
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│ Userspace │ ──────────────────────────→│ Kernel │
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│ Process A │ open/read/write/fevent │ Scheme │
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│ │ ←──────────────────────────│ Dispatch │
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└─────────────┘ result (usize/-errno) └──────┬───────┘
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│
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┌─────────────────────┤
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│ │
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┌────▼──────┐ ┌──────▼──────┐
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│ Kernel │ │ Userspace │
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│ Schemes │ │ Scheme │
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│ (12) │ │ Daemons │
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│ │ │ (via user:) │
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│ debug: │ │ │
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│ event: │ │ ptyd │
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│ memory: │ │ pcid │
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│ pipe: │ │ ext4d │
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│ irq: │ │ fatd │
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│ time: │ │ redox-drm │
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│ sys: │ │ ... │
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│ proc: │ │ │
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│ serio: │ │ │
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└───────────┘ └──────────────┘
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```
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**IPC primitives available:**
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| Primitive | Mechanism | Kernel/Userspace |
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|-----------|-----------|-----------------|
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| `pipe:` scheme | Kernel pipe scheme — bidirectional byte streams | Kernel |
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| `shm_open()` / `mmap(MAP_SHARED)` | Shared memory via memory scheme grants | Kernel |
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| `SYS_CALL` + scheme messages | Send/receive typed messages to scheme daemons | Kernel dispatch, userspace handler |
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| `fevent()` | Register kernel-level events on file descriptors | Kernel |
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| `sendfd()` | Pass file descriptors between processes | Kernel |
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| `event:` scheme | Kernel event notification (used by eventfd/signalfd/timerfd) | Kernel |
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| Signals | `sigprocmask` + `sigaction` via proc: scheme | Kernel delivery, userspace handling |
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| Futex | Fast userspace mutex via `SYS_FUTEX` | Kernel |
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**Current IPC limitations:**
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| Limitation | Impact |
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|-----------|--------|
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| No `SYS_PTRACE` | ptrace not available (handled via proc: scheme paths) |
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| No `SYS_KILL` | Signal sending via proc: scheme only |
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| eventfd/signalfd/timerfd recipe-applied | Bounded compatibility layers, not plain-source |
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| `ifaddrs` synthetic | Only `loopback` + `eth0`, not live enumeration |
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| POSIX message queues not implemented | `mqueue.h` missing entirely |
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| SysV message queues not implemented | `sys/msg.h` missing entirely |
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| No UNIX domain sockets (`AF_UNIX`) path | Socket-based IPC limited |
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### 2.5 Process Model
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Redox uses a **userspace process manager** (`procmgr` via `proc:` scheme):
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- **fork**: Implemented through proc: scheme → kernel creates new Context with cloned address space
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- **exec**: Replaces address space with new executable image
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- **spawn**: Combined fork+exec via proc: scheme
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- **wait/waitpid/waitid**: Recipe-applied patch via proc: scheme (signals child exit)
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- **Credentials on fork**: Address space cloned (userspace `DYNAMIC_PROC_INFO` inherited)
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- **Credentials on exec**: `setresuid()` behavior (suid-bit not implemented in kernel)
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The kernel's Context struct tracks:
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- `owner_proc_id: Option<NonZeroUsize>` — parent process for exit notification
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- `files: Arc<LockedFdTbl>` — file descriptor table (can be shared)
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- `addr_space: Option<Arc<AddrSpaceWrapper>>` — address space (can be shared = threads)
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- `sig: Option<SignalState>` — signal handler configuration
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## 3. Critical Gaps and Blockers
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### 3.1 Credential Syscall Blocker (Priority: P0-CRITICAL)
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The `setgroups()` function is **ENOSYS**. This blocks:
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- `polkit` — uses `setgroups()` for privilege management
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- `dbus-daemon` — uses credentials for service activation
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- `logind` / `redbear-sessiond` — needs credential awareness
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- `sudo` / `su` — uses `initgroups()` → `setgroups()`
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- Any program that changes user identity
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**Root cause chain:**
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1. `redox_syscall` crate (crates.io, upstream) has no `SYS_SETGROUPS`/`SYS_GETGROUPS` numbers
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2. Kernel has no supplementary group table in Context struct
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3. No group inheritance on fork/exec
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4. relibc `setgroups()` is a `todo_skip!()` stub
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5. `getgroups()` bypasses kernel entirely (reads /etc/group)
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### 3.2 Kernel-Level Access Control Gap (Priority: P1)
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The kernel's `caller_ctx()` provides `{euid, egid, pid}` to scheme handlers, but:
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1. **No consistent enforcement**: Kernel schemes may or may not check caller credentials
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2. **No ruid/suid tracking**: Cannot distinguish real vs effective identity in kernel
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3. **All processes start as root** (euid=0, egid=0): No privilege separation at boot
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4. **No supplementary groups in kernel**: Only egid checked
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### 3.3 IPC Completeness Gaps (Priority: P2)
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| Gap | Priority | Blocked By |
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|-----|----------|------------|
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| POSIX message queues (`mqueue.h`) | P2 | Scheme design needed |
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| SysV message queues (`sys/msg.h`) | P2 | Scheme design needed |
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| UNIX domain sockets (`AF_UNIX`) | P2 | Kernel or scheme implementation |
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| Non-synthetic `ifaddrs` | P3 | Network stack enumeration |
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| eventfd/signalfd/timerfd → plain-source | P3 | Upstream relibc convergence |
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### 3.4 Resource Limits (Priority: P2)
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`SYS_GETRLIMIT` / `SYS_SETRLIMIT` return ENOSYS. This is a microkernel design choice:
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- Resource limits are typically library-level policy in capability systems
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- Current approach: limits enforced in userspace daemons
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- Desktop impact: systemd/logind expect rlimit support for service management
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### 3.5 Shutdown Robustness (Priority: P2)
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ACPI shutdown via `kstop` eventing exists but has gaps:
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- `acpid` startup has panic-grade `expect` paths
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- `_S5` derivation gated on PCI timing
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- DMAR orphaned in `acpid` source
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- See `local/docs/ACPI-IMPROVEMENT-PLAN.md` for full detail
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## 4. Implementation Plan
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### Phase K1: Kernel Credential Foundation (Week 1-2)
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**Goal**: Add supplementary group support to the kernel and wire `setgroups()`/`getgroups()`.
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#### K1.1 — Add supplementary groups to kernel Context
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```rust
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// Context struct additions (context/context.rs):
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pub struct Context {
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// Existing:
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pub euid: u32,
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pub egid: u32,
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pub pid: usize,
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// NEW: Real/saved IDs (moved from userspace redox-rt to kernel):
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pub ruid: u32,
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pub rgid: u32,
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pub suid: u32,
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pub sgid: u32,
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// NEW: Supplementary groups
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pub groups: Vec<u32>, // Or Arc<[u32]> for sharing
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}
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```
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**Files modified:**
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- `recipes/core/kernel/source/src/context/context.rs` — add fields, initialize, clone on fork
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- `recipes/core/kernel/source/src/scheme/proc.rs` — extend `ProcSchemeAttrs` to include ruid/suid/rgid/sgid/groups
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- `local/patches/kernel/` — new patch: `P4-credential-fields.patch`
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#### K1.2 — Add `SYS_SETGROUPS` and `SYS_GETGROUPS` to redox_syscall
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The `redox_syscall` crate is upstream (crates.io). Red Bear must either:
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- **Option A (preferred)**: Contribute upstream PR to add syscall numbers
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- **Option B**: Vendor fork of `redox_syscall` in `local/` overlay
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- **Option C**: Define Red Bear-local syscall numbers in kernel directly
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**Recommended: Option A + B fallback**:
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1. Submit upstream PR to `redox_syscall` adding:
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- `SYS_SETGROUPS`, `SYS_GETGROUPS`
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- `SYS_SETUID`, `SYS_SETGID`, `SYS_GETUID`, `SYS_GETGID`
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- `SYS_GETEUID`, `SYS_GETEGID`
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- `SYS_SETREUID`, `SYS_SETREGID`
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- `SYS_GETRESUID`, `SYS_GETRESGID`
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2. While upstream PR is pending, use a local `redox_syscall` patch:
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- Copy `redox_syscall` crate into `local/vendor/redox_syscall/`
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- Add syscall number constants
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- Point kernel Cargo.toml to local path
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- Patch tracked in `local/patches/kernel/P4-redox-syscall-numbers.patch`
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#### K1.3 — Add kernel syscall handlers
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**New file:** `recipes/core/kernel/source/src/syscall/cred.rs`
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```rust
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// Credential syscall handlers
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pub fn setresuid(ruid: u32, euid: u32, suid: u32, token: &mut CleanLockToken) -> Result<usize> {
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let context_lock = context::current();
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let mut context = context_lock.write(token.token());
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// Permission check: must be root or match current values
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if context.euid != 0 {
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if let Some(ruid) = ruid_opt { /* check ruid == current ruid/euid/suid */ }
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// ... POSIX permission model
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}
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// Set values
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if ruid != u32::MAX { context.ruid = ruid; }
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if euid != u32::MAX { context.euid = euid; }
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if suid != u32::MAX { context.suid = suid; }
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Ok(0)
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}
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pub fn setgroups(groups: &[u32], token: &mut CleanLockToken) -> Result<usize> {
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// Requires: euid == 0
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let context_lock = context::current();
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let mut context = context_lock.write(token.token());
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if context.euid != 0 { return Err(Error::new(EPERM)); }
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context.groups = groups.to_vec();
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Ok(0)
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}
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pub fn getgroups(token: &mut CleanLockToken) -> Result<Vec<u32>> {
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let context_lock = context::current();
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let context = context_lock.read(token.token());
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Ok(context.groups.clone())
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}
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```
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**Modified file:** `recipes/core/kernel/source/src/syscall/mod.rs`
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```rust
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match a {
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// ... existing arms ...
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SYS_SETRESUID => setresuid(b as u32, c as u32, d as u32, token),
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SYS_SETRESGID => setresgid(b as u32, c as u32, d as u32, token),
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SYS_GETRESUID => getresuid(UserSlice::wo(b, c)?, token),
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SYS_GETRESGID => getresgid(UserSlice::wo(b, c)?, token),
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SYS_SETUID => setuid(b as u32, token),
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SYS_SETGID => setgid(b as u32, token),
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SYS_GETUID => Ok(getuid(token)),
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SYS_GETGID => Ok(getgid(token)),
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SYS_GETEUID => Ok(geteuid(token)),
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SYS_GETEGID => Ok(getegid(token)),
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SYS_SETGROUPS => setgroups(UserSlice::ro(b, c)?, token).map(|()| 0),
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SYS_GETGROUPS => getgroups(UserSlice::wo(b, c)?, token),
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// ... existing arms ...
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}
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```
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#### K1.4 — Wire relibc setgroups()/getgroups() through real syscalls
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**Modified:** `recipes/core/relibc/source/src/platform/redox/mod.rs`
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```rust
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// Replace todo_skip!() stub:
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unsafe fn setgroups(size: size_t, list: *const gid_t) -> Result<()> {
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if size < 0 || size > NGROUPS_MAX { return Err(Errno(EINVAL)); }
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let groups = core::slice::from_raw_parts(list, size as usize);
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syscall::setgroups(groups)?;
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Ok(())
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}
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// Replace /etc/group-based getgroups:
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fn getgroups(mut list: Out<[gid_t]>) -> Result<c_int> {
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let mut buf = [0u32; NGROUPS_MAX as usize];
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let count = syscall::getgroups(&mut buf)?;
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for (i, gid) in buf[..count].iter().enumerate() {
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list[i] = *gid as gid_t;
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}
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Ok(count as c_int)
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}
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```
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#### K1.5 — Add credential syscall stubs in redox-rt
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**Modified:** `recipes/core/relibc/source/redox-rt/src/sys.rs`
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```rust
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pub fn setgroups(groups: &[u32]) -> Result<()> {
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unsafe {
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redox_syscall::syscall5(
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redox_syscall::SYS_SETGROUPS,
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groups.as_ptr() as usize,
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groups.len(),
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0, 0, 0,
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)
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.map(|_| ())
|
||
.map_err(|e| Error::new(e.errno as i32))
|
||
}
|
||
}
|
||
|
||
pub fn getgroups(buf: &mut [u32]) -> Result<usize> {
|
||
unsafe {
|
||
redox_syscall::syscall3(
|
||
redox_syscall::SYS_GETGROUPS,
|
||
buf.as_mut_ptr() as usize,
|
||
buf.len(),
|
||
0,
|
||
)
|
||
.map_err(|e| Error::new(e.errno as i32))
|
||
}
|
||
}
|
||
```
|
||
|
||
#### K1.6 — Patch management
|
||
|
||
All kernel and relibc source changes must be mirrored into `local/patches/`:
|
||
|
||
```bash
|
||
local/patches/
|
||
├── kernel/
|
||
│ ├── redox.patch # Updated symlink target
|
||
│ ├── P4-credential-fields.patch # Context struct additions
|
||
│ ├── P4-credential-syscalls.patch # Syscall handlers + dispatch
|
||
│ └── P4-redox-syscall-numbers.patch # Local redox_syscall additions
|
||
├── relibc/
|
||
│ ├── P4-setgroups-kernel.patch # Setgroups through real syscall
|
||
│ ├── P4-getgroups-kernel.patch # Getgroups through real syscall
|
||
│ └── P4-redox-rt-cred-syscalls.patch # redox-rt syscall wrappers
|
||
```
|
||
|
||
### Phase K2: Kernel Access Control Hardening (Week 2-3)
|
||
|
||
**Goal**: Enforce credential checks in kernel schemes, add proper privilege separation.
|
||
|
||
#### K2.1 — Enforce scheme-level credential checks
|
||
|
||
Each kernel scheme handler currently receives `CallerCtx { uid, gid, pid }`. Ensure consistent
|
||
credential enforcement:
|
||
|
||
| Scheme | Current Check | Required Check |
|
||
|--------|--------------|----------------|
|
||
| `memory:` | Physical memory access → root only | ✅ Already enforced (euid==0 for phys) |
|
||
| `irq:` | IRQ registration → root only | ✅ Already enforced |
|
||
| `proc:` | Process inspection → caller == target OR root | 🔄 Review: ensure consistent |
|
||
| `sys:` | System info → read-only for all | ✅ Appropriate |
|
||
| `debug:` | Debug output → should be root-only | 🔄 Review: add check |
|
||
| `serio:` | PS/2 device → root only | 🔄 Review: add check |
|
||
| `event:` | Event registration → process-own only | 🔄 Review: ensure isolation |
|
||
|
||
#### K2.2 — Bootstrap with non-root init process
|
||
|
||
Currently all processes start as euid=0/egid=0. The boot sequence should:
|
||
1. Kernel bootstrap context starts as root (euid=0, egid=0) — required for init
|
||
2. Init (`/sbin/init`) runs as root
|
||
3. Init drops privileges before spawning user services:
|
||
```rust
|
||
// In init or service manager:
|
||
setresuid(1000, 1000, 1000); // Drop to regular user
|
||
setgroups(&[1000, 27, 100]); // Set supplementary groups
|
||
// Then spawn child services with restricted permissions
|
||
```
|
||
|
||
#### K2.3 — Add `initgroups()` support
|
||
|
||
```rust
|
||
// In relibc/src/platform/redox/mod.rs:
|
||
fn initgroups(user: CStr, group: gid_t) -> Result<()> {
|
||
// 1. Set primary group
|
||
setgid(group)?;
|
||
// 2. Parse /etc/group for supplementary groups containing this user
|
||
let mut groups = vec![group];
|
||
// ... iterate getgrent() to find user memberships ...
|
||
// 3. Set supplementary groups via kernel syscall
|
||
setgroups(&groups)?;
|
||
Ok(())
|
||
}
|
||
```
|
||
|
||
### Phase K3: IPC Infrastructure Improvements (Week 3-5)
|
||
|
||
**Goal**: Complete IPC primitives needed for desktop infrastructure.
|
||
|
||
#### K3.1 — POSIX Message Queues (`mqueue.h`)
|
||
|
||
**Design decision**: Implement as a userspace scheme daemon (not kernel syscalls).
|
||
|
||
```
|
||
mqd:
|
||
├── Registers as scheme:mqueue
|
||
├── Stores queues in memory backed by shm_open() + mmap()
|
||
├── mq_open() → open scheme:mqueue/{name}
|
||
├── mq_send() → write to fd
|
||
├── mq_receive() → read from fd
|
||
├── mq_notify() → fevent() on fd for async notification
|
||
├── mq_close() → close fd
|
||
└── mq_unlink() → unlink scheme:mqueue/{name}
|
||
```
|
||
|
||
**Implementation:**
|
||
- New Red Bear package: `local/recipes/system/mqueued/`
|
||
- Relibc header: `recipes/core/relibc/source/src/header/mqueue/`
|
||
- Recipe in `local/recipes/system/mqueued/recipe.toml`
|
||
- Init service: `/usr/lib/init.d/50_mqueued.service`
|
||
|
||
#### K3.2 — SysV Message Queues (`sys/msg.h`)
|
||
|
||
**Design decision**: Implement as scheme daemon or on top of POSIX message queues.
|
||
- Recommended: implement directly alongside `mqueued` using shared infrastructure.
|
||
- Low priority — Qt/KDE do not depend on SysV msg queues.
|
||
|
||
#### K3.3 — UNIX Domain Sockets (`AF_UNIX` / `SOCK_STREAM`)
|
||
|
||
**Current state**: D-Bus uses abstract sockets on Linux. Redox uses scheme-based communication.
|
||
- For D-Bus compatibility: `redbear-sessiond` already uses `zbus` with custom transport
|
||
- For general `AF_UNIX`: implement as `scheme:unix` daemon backed by kernel pipe scheme
|
||
- Priority: P3 — D-Bus is already working through scheme transport
|
||
|
||
#### K3.4 — Non-synthetic Interface Enumeration
|
||
|
||
Replace the hardcoded `loopback` + `eth0` model with live network interface enumeration:
|
||
- Query `smolnetd` or equivalent for active interfaces
|
||
- Expose through `getifaddrs()` properly
|
||
- Priority: P3 — needed for NetworkManager-like functionality
|
||
|
||
#### K3.5 — eventfd/signalfd/timerfd → plain-source convergence
|
||
|
||
Current state: all three are recipe-applied patches. Goal: upstream into relibc mainline.
|
||
- Monitor upstream relibc for equivalent implementations
|
||
- When upstream absorbs: shrink/drop Red Bear patch chain
|
||
- When upstream does NOT absorb after 3+ months: promote to durable Red Bear-maintained
|
||
- See `local/docs/RELIBC-IPC-ASSESSMENT-AND-IMPROVEMENT-PLAN.md` Phase I5
|
||
|
||
### Phase K4: Resource Limits and Process Management (Week 4-6)
|
||
|
||
#### K4.1 — RLIMIT Support
|
||
|
||
**Decision**: Enforce resource limits in userspace, not kernel.
|
||
- The kernel is a microkernel — resource limits are policy
|
||
- `getrlimit()` / `setrlimit()` → libc stubs with reasonable defaults
|
||
- Process enforcement → `procmgr` (userspace process manager) via proc: scheme
|
||
- File descriptor limits → already enforced via `CONTEXT_MAX_FILES` in kernel
|
||
- Memory limits → userspace `procmgr` can kill processes exceeding limits
|
||
|
||
```rust
|
||
// relibc implementation (userspace, no kernel changes needed):
|
||
fn getrlimit(resource: c_int, rlim: *mut rlimit) -> Result<()> {
|
||
match resource {
|
||
RLIMIT_NOFILE => { rlim.rlim_cur = 1024; rlim.rlim_max = 4096; }
|
||
RLIMIT_NPROC => { rlim.rlim_cur = 256; rlim.rlim_max = 1024; }
|
||
RLIMIT_AS => { rlim.rlim_cur = RLIM_INFINITY; rlim.rlim_max = RLIM_INFINITY; }
|
||
RLIMIT_CORE => { rlim.rlim_cur = 0; rlim.rlim_max = RLIM_INFINITY; }
|
||
// ... other resource types with reasonable defaults
|
||
_ => return Err(Errno(EINVAL)),
|
||
}
|
||
Ok(())
|
||
}
|
||
```
|
||
|
||
#### K4.2 — PTRACE via proc: scheme
|
||
|
||
`SYS_PTRACE` is not implemented as a direct syscall. The Redox model uses the `proc:` scheme
|
||
for process inspection and manipulation:
|
||
- Already partially implemented in `scheme/proc.rs`
|
||
- Memory read/write through proc: scheme file operations
|
||
- Register read/write through proc: scheme
|
||
- Signal injection through proc: scheme
|
||
|
||
Improvements needed:
|
||
- Document the proc: scheme ptrace API surface
|
||
- Ensure all ptrace operations have proc: scheme equivalents
|
||
- Add `PTRACE_*` constants to redox_syscall for compatibility
|
||
|
||
#### K4.3 — clock_settime
|
||
|
||
`SYS_CLOCK_SETTIME` returns ENOSYS. Implementation:
|
||
- Add scheme write path to `/scheme/sys/update_time_offset`
|
||
- Or implement as direct syscall for precision
|
||
- Priority: P3 — needed for NTP synchronization
|
||
|
||
### Phase K5: Shutdown and Power Management (Week 5-7)
|
||
|
||
See `local/docs/ACPI-IMPROVEMENT-PLAN.md` for full ACPI plan. This section covers kernel-specific
|
||
work only.
|
||
|
||
#### K5.1 — Hardened acpid Startup
|
||
|
||
- Remove panic-grade `expect` paths in kernel ACPI/AML handling
|
||
- Add graceful fallback when ACPI tables are missing or malformed
|
||
- See ACPI-IMPROVEMENT-PLAN.md Wave 1
|
||
|
||
#### K5.2 — kstop Shutdown Robustness
|
||
|
||
- Current: `_S5` shutdown via `kstop` event exists but gated on PCI timing
|
||
- Required: deterministic shutdown ordering:
|
||
1. Notify userspace services of impending shutdown
|
||
2. Sync filesystems
|
||
3. Power off via ACPI/FADT
|
||
- See ACPI-IMPROVEMENT-PLAN.md Wave 2
|
||
|
||
#### K5.3 — Sleep State Support
|
||
|
||
- S3 (suspend-to-RAM) and S4 (hibernate) are not yet supported
|
||
- Requires: kernel state serialization, device reinitialization
|
||
- Priority: P4 — long-term, not blocking desktop
|
||
|
||
## 5. Dependency Chain
|
||
|
||
```
|
||
Phase K1 (credential syscalls) ─────────────────────┐
|
||
│ │
|
||
├──► polkit compatibility │
|
||
├──► dbus-daemon credential checks │
|
||
├──► sudo/su user switching │
|
||
├──► redbear-sessiond login1 handoff │
|
||
└──► greeter/session-launch credential drop │
|
||
│
|
||
Phase K2 (access control) ────────────────────────────┤
|
||
│ │
|
||
├──► Privilege-separated boot sequence │
|
||
├──► Scheme-level credential enforcement │
|
||
└──► initgroups() for service launching │
|
||
│
|
||
Phase K3 (IPC) ───────────────────────────────────────┤
|
||
│ │
|
||
├──► POSIX message queues → needed by some apps │
|
||
├──► AF_UNIX → broader D-Bus transport options │
|
||
└──► eventfd/signalfd/timerfd → KDE/Qt runtime │
|
||
│
|
||
Phase K4 (limits/ptrace) ─────────────────────────────┤
|
||
│ │
|
||
├──► RLIMIT → systemd/logind compatibility │
|
||
├──► PTRACE → debugging support │
|
||
└──► clock_settime → NTP synchronization │
|
||
▼
|
||
Desktop infrastructure
|
||
ready for KDE Plasma
|
||
```
|
||
|
||
## 6. Integration with Existing Work
|
||
|
||
### 6.1 Already in Progress (do not duplicate)
|
||
|
||
| Area | Canonical Plan | Status |
|
||
|------|---------------|--------|
|
||
| IRQ / MSI-X / IOMMU | `IRQ-AND-LOWLEVEL-CONTROLLERS-ENHANCEMENT-PLAN.md` | Waves 1-6 complete, hardware validation open |
|
||
| ACPI shutdown / power | `ACPI-IMPROVEMENT-PLAN.md` | Waves 1-2 complete, sleep states deferred |
|
||
| relibc IPC surface | `RELIBC-IPC-ASSESSMENT-AND-IMPROVEMENT-PLAN.md` | Phases I1-I5, message queues deferred |
|
||
| D-Bus / sessiond | `DBUS-INTEGRATION-PLAN.md` | Phase 1 complete, Phase 2 in progress |
|
||
| Greeter / login | `GREETER-LOGIN-IMPLEMENTATION-PLAN.md` | Active, bounded proof passing |
|
||
| Desktop path | `CONSOLE-TO-KDE-DESKTOP-PLAN.md` | Phase 1-5 model, KWin building |
|
||
|
||
### 6.2 This Plan Covers (uniquely)
|
||
|
||
| Area | This Plan | Not Covered By |
|
||
|------|-----------|---------------|
|
||
| Kernel credential architecture | §3, Phase K1 | Any existing plan |
|
||
| Kernel access control hardening | §3.2, Phase K2 | Any existing plan |
|
||
| `setgroups()` / `getgroups()` kernel implementation | Phase K1.2-K1.4 | Only stub noted elsewhere |
|
||
| Supplementary group infrastructure | Phase K1.1 | Not covered anywhere |
|
||
| POSIX/SysV message queues | Phase K3.1-K3.2 | Deferred in relibc-IPC plan |
|
||
| UNIX domain sockets | Phase K3.3 | Not covered |
|
||
| RLIMIT design decision | Phase K4.1 | Noted as gap only |
|
||
| PTRACE via proc: scheme | Phase K4.2 | Not covered |
|
||
| clock_settime implementation | Phase K4.3 | Noted as gap only |
|
||
|
||
## 7. Patch Governance
|
||
|
||
All kernel and relibc source changes must follow the durability policy (see `local/AGENTS.md`):
|
||
|
||
1. **Make changes** in `recipes/core/kernel/source/` or `recipes/core/relibc/source/`
|
||
2. **Generate patches**: `git diff` in the source tree → `local/patches/<component>/P4-*.patch`
|
||
3. **Wire patches** into `recipes/core/<component>/recipe.toml` patches list
|
||
4. **Commit** patches + recipe changes before session end
|
||
5. **Assume** source trees may be thrown away by `make distclean` or upstream refresh
|
||
|
||
### Patch naming convention:
|
||
```
|
||
local/patches/kernel/P4-credential-fields.patch
|
||
local/patches/kernel/P4-credential-syscalls.patch
|
||
local/patches/kernel/P4-redox-syscall-numbers.patch
|
||
local/patches/relibc/P4-setgroups-kernel.patch
|
||
local/patches/relibc/P4-getgroups-kernel.patch
|
||
local/patches/relibc/P4-redox-rt-cred-syscalls.patch
|
||
local/patches/relibc/P4-initgroups.patch
|
||
```
|
||
|
||
## 8. Validation and Evidence
|
||
|
||
### 8.1 Build Evidence
|
||
|
||
| Check | Command |
|
||
|-------|---------|
|
||
| Kernel compiles | `make r.kernel` |
|
||
| relibc compiles | `make r.relibc` |
|
||
| Full OS builds | `make all CONFIG_NAME=redbear-full` |
|
||
|
||
### 8.2 Runtime Evidence
|
||
|
||
| Test | Verification |
|
||
|------|-------------|
|
||
| `getuid()` returns non-zero after login | `id` command in guest |
|
||
| `setgroups()` succeeds for root | `sudo -u user id` in guest |
|
||
| `setresuid()` properly changes euid | `su user -c 'id'` |
|
||
| `initgroups()` populates groups | `groups` command in guest |
|
||
| Credentials survive fork | `bash -c 'id'` |
|
||
| Credentials dropped on exec (if SUID implemented) | TBD |
|
||
| polkit can query credentials | `pkexec echo ok` |
|
||
| dbus-daemon starts without errors | `dbus-monitor` |
|
||
|
||
### 8.3 Verification Scripts
|
||
|
||
Create bounded proof scripts:
|
||
```bash
|
||
local/scripts/test-credential-syscalls-qemu.sh # QEMU launcher
|
||
local/scripts/test-credential-syscalls-guest.sh # In-guest checker
|
||
```
|
||
|
||
## 9. References
|
||
|
||
- `local/docs/COMPREHENSIVE-OS-ASSESSMENT.md` — Canonical comprehensive plan
|
||
- `docs/01-REDOX-ARCHITECTURE.md` — Architecture reference
|
||
- `local/docs/IRQ-AND-LOWLEVEL-CONTROLLERS-ENHANCEMENT-PLAN.md` — IRQ/PCI plan (sibling)
|
||
- `local/docs/RELIBC-IPC-ASSESSMENT-AND-IMPROVEMENT-PLAN.md` — IPC surface plan (companion)
|
||
- `local/docs/ACPI-IMPROVEMENT-PLAN.md` — ACPI/shutdown plan (sibling)
|
||
- `local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md` — Desktop path plan (consumer)
|
||
- `recipes/core/kernel/source/src/syscall/mod.rs` — Syscall dispatch (primary implementation target)
|
||
- `recipes/core/kernel/source/src/context/context.rs` — Context struct (credential fields)
|
||
- `recipes/core/kernel/source/src/scheme/proc.rs` — Proc scheme (credential setting)
|
||
- `recipes/core/relibc/source/src/platform/redox/mod.rs` — relibc Redox platform (credential stubs)
|
||
- `recipes/core/relibc/source/redox-rt/src/sys.rs` — redox-rt credential primitives
|