github.com/MerlinKodo/gvisor@v0.0.0-20231110090155-957f62ecf90e/pkg/sentry/kernel/context.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package kernel
    16  
    17  import (
    18  	"github.com/MerlinKodo/gvisor/pkg/context"
    19  	"github.com/MerlinKodo/gvisor/pkg/sentry/kernel/ipc"
    20  )
    21  
    22  // contextID is the kernel package's type for context.Context.Value keys.
    23  type contextID int
    24  
    25  const (
    26  	// CtxCanTrace is a Context.Value key for a function with the same
    27  	// signature and semantics as kernel.Task.CanTrace.
    28  	CtxCanTrace contextID = iota
    29  
    30  	// CtxKernel is a Context.Value key for a Kernel.
    31  	CtxKernel
    32  
    33  	// CtxPIDNamespace is a Context.Value key for a PIDNamespace.
    34  	CtxPIDNamespace
    35  
    36  	// CtxTask is a Context.Value key for a Task.
    37  	CtxTask
    38  
    39  	// CtxUTSNamespace is a Context.Value key for a UTSNamespace.
    40  	CtxUTSNamespace
    41  )
    42  
    43  // ContextCanTrace returns true if ctx is permitted to trace t, in the same sense
    44  // as kernel.Task.CanTrace.
    45  func ContextCanTrace(ctx context.Context, t *Task, attach bool) bool {
    46  	if v := ctx.Value(CtxCanTrace); v != nil {
    47  		return v.(func(*Task, bool) bool)(t, attach)
    48  	}
    49  	return false
    50  }
    51  
    52  // KernelFromContext returns the Kernel in which ctx is executing, or nil if
    53  // there is no such Kernel.
    54  func KernelFromContext(ctx context.Context) *Kernel {
    55  	if v := ctx.Value(CtxKernel); v != nil {
    56  		return v.(*Kernel)
    57  	}
    58  	return nil
    59  }
    60  
    61  // PIDNamespaceFromContext returns the PID namespace in which ctx is executing,
    62  // or nil if there is no such PID namespace.
    63  func PIDNamespaceFromContext(ctx context.Context) *PIDNamespace {
    64  	if v := ctx.Value(CtxPIDNamespace); v != nil {
    65  		return v.(*PIDNamespace)
    66  	}
    67  	return nil
    68  }
    69  
    70  // UTSNamespaceFromContext returns the UTS namespace in which ctx is executing,
    71  // or nil if there is no such UTS namespace.
    72  func UTSNamespaceFromContext(ctx context.Context) *UTSNamespace {
    73  	if v := ctx.Value(CtxUTSNamespace); v != nil {
    74  		return v.(*UTSNamespace)
    75  	}
    76  	return nil
    77  }
    78  
    79  // IPCNamespaceFromContext returns the IPC namespace in which ctx is executing,
    80  // or nil if there is no such IPC namespace. It takes a reference on the
    81  // namespace.
    82  func IPCNamespaceFromContext(ctx context.Context) *IPCNamespace {
    83  	if v := ctx.Value(ipc.CtxIPCNamespace); v != nil {
    84  		return v.(*IPCNamespace)
    85  	}
    86  	return nil
    87  }
    88  
    89  // TaskFromContext returns the Task associated with ctx, or nil if there is no
    90  // such Task.
    91  func TaskFromContext(ctx context.Context) *Task {
    92  	if v := ctx.Value(CtxTask); v != nil {
    93  		return v.(*Task)
    94  	}
    95  	return nil
    96  }