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sandbox: expose seccomp interface

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There's no point in artificially limiting and abstracting away these options. The higher level hakurei package is responsible for providing a secure baseline and sane defaults. The sandbox package should present everything to the caller.

Signed-off-by: Ophestra <cat@gensokyo.uk>
This commit is contained in:
Ophestra
2025-07-02 04:38:28 +09:00
parent a6887f7253
commit 31aef905fa
12 changed files with 117 additions and 77 deletions
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55
sandbox/container.go
View File

@@ -17,32 +17,6 @@ import (
"git.gensokyo.uk/security/hakurei/sandbox/seccomp"
)
type HardeningFlags uintptr
const (
FSyscallCompat HardeningFlags = 1 << iota
FAllowDevel
FAllowUserns
FAllowTTY
FAllowNet
)
func (flags HardeningFlags) seccomp(presets seccomp.FilterPreset) seccomp.FilterPreset {
if flags&FSyscallCompat == 0 {
presets |= seccomp.PresetExt
}
if flags&FAllowDevel == 0 {
presets |= seccomp.PresetDenyDevel
}
if flags&FAllowUserns == 0 {
presets |= seccomp.PresetDenyNS
}
if flags&FAllowTTY == 0 {
presets |= seccomp.PresetDenyTTY
}
return presets
}
type (
// Container represents a container environment being prepared or run.
// None of [Container] methods are safe for concurrent use.
@@ -94,17 +68,23 @@ type (
Hostname string
// Sequential container setup ops.
*Ops
// Seccomp system call filter rules.
SeccompRules []seccomp.NativeRule
// Extra seccomp flags.
SeccompFlags seccomp.ExportFlag
// Extra seccomp presets.
// Seccomp presets. Has no effect unless SeccompRules is zero-length.
SeccompPresets seccomp.FilterPreset
// Do not load seccomp program.
SeccompDisable bool
// Permission bits of newly created parent directories.
// The zero value is interpreted as 0755.
ParentPerm os.FileMode
// Do not syscall.Setsid.
RetainSession bool
// Do not [syscall.CLONE_NEWNET].
HostNet bool
// Retain CAP_SYS_ADMIN.
Privileged bool
Flags HardeningFlags
}
)
@@ -120,7 +100,7 @@ func (p *Container) Start() error {
p.cancel = cancel
var cloneFlags uintptr = CLONE_NEWIPC | CLONE_NEWUTS | CLONE_NEWCGROUP
if p.Flags&FAllowNet == 0 {
if !p.HostNet {
cloneFlags |= CLONE_NEWNET
}
@@ -132,6 +112,10 @@ func (p *Container) Start() error {
p.Gid = OverflowGid()
}
if !p.RetainSession {
p.SeccompPresets |= seccomp.PresetDenyTTY
}
if p.CommandContext != nil {
p.cmd = p.CommandContext(ctx)
} else {
@@ -148,7 +132,7 @@ func (p *Container) Start() error {
}
p.cmd.Dir = "/"
p.cmd.SysProcAttr = &SysProcAttr{
Setsid: p.Flags&FAllowTTY == 0,
Setsid: !p.RetainSession,
Pdeathsig: SIGKILL,
Cloneflags: cloneFlags | CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNS,
@@ -211,6 +195,11 @@ func (p *Container) Serve() error {
}
}
if p.SeccompRules == nil {
// do not transmit nil
p.SeccompRules = make([]seccomp.NativeRule, 0)
}
err := setup.Encode(
&initParams{
p.Params,
@@ -229,8 +218,8 @@ func (p *Container) Serve() error {
func (p *Container) Wait() error { defer p.cancel(); return p.cmd.Wait() }
func (p *Container) String() string {
return fmt.Sprintf("argv: %q, flags: %#x, seccomp: %#x, presets: %#x",
p.Args, p.Flags, int(p.SeccompFlags), int(p.Flags.seccomp(p.SeccompPresets)))
return fmt.Sprintf("argv: %q, filter: %v, rules: %d, flags: %#x, presets: %#x",
p.Args, !p.SeccompDisable, len(p.SeccompRules), int(p.SeccompFlags), int(p.SeccompPresets))
}
func New(ctx context.Context, name string, args ...string) *Container {