github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/kernel/auth/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 auth
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/context"
    19  )
    20  
    21  // contextID is the auth package's type for context.Context.Value keys.
    22  type contextID int
    23  
    24  const (
    25  	// CtxCredentials is a Context.Value key for Credentials.
    26  	CtxCredentials contextID = iota
    27  )
    28  
    29  // CredentialsFromContext returns a copy of the Credentials used by ctx, or a
    30  // set of Credentials with no capabilities if ctx does not have Credentials.
    31  func CredentialsFromContext(ctx context.Context) *Credentials {
    32  	if v := ctx.Value(CtxCredentials); v != nil {
    33  		return v.(*Credentials)
    34  	}
    35  	return NewAnonymousCredentials()
    36  }
    37  
    38  // ContextWithCredentials returns a copy of ctx carrying creds.
    39  func ContextWithCredentials(ctx context.Context, creds *Credentials) context.Context {
    40  	return &authContext{ctx, creds}
    41  }
    42  
    43  type authContext struct {
    44  	context.Context
    45  	creds *Credentials
    46  }
    47  
    48  // Value implements context.Context.
    49  func (ac *authContext) Value(key interface{}) interface{} {
    50  	switch key {
    51  	case CtxCredentials:
    52  		return ac.creds
    53  	default:
    54  		return ac.Context.Value(key)
    55  	}
    56  }