github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/syscalls/linux/sys_rseq.go (about)

     1  // Copyright 2019 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 linux
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    19  	"github.com/SagerNet/gvisor/pkg/errors/linuxerr"
    20  	"github.com/SagerNet/gvisor/pkg/sentry/arch"
    21  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    22  	"github.com/SagerNet/gvisor/pkg/syserror"
    23  )
    24  
    25  // RSeq implements syscall rseq(2).
    26  func RSeq(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
    27  	addr := args[0].Pointer()
    28  	length := args[1].Uint()
    29  	flags := args[2].Int()
    30  	signature := args[3].Uint()
    31  
    32  	if !t.RSeqAvailable() {
    33  		// Event for applications that want rseq on a configuration
    34  		// that doesn't support them.
    35  		t.Kernel().EmitUnimplementedEvent(t)
    36  		return 0, nil, syserror.ENOSYS
    37  	}
    38  
    39  	switch flags {
    40  	case 0:
    41  		// Register.
    42  		return 0, nil, t.SetRSeq(addr, length, signature)
    43  	case linux.RSEQ_FLAG_UNREGISTER:
    44  		return 0, nil, t.ClearRSeq(addr, length, signature)
    45  	default:
    46  		// Unknown flag.
    47  		return 0, nil, linuxerr.EINVAL
    48  	}
    49  }