github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fsimpl/sys/kcov.go (about)

     1  // Copyright 2020 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 sys
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/abi/linux"
    19  	"github.com/SagerNet/gvisor/pkg/context"
    20  	"github.com/SagerNet/gvisor/pkg/errors/linuxerr"
    21  	"github.com/SagerNet/gvisor/pkg/sentry/arch"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/fsimpl/kernfs"
    23  	"github.com/SagerNet/gvisor/pkg/sentry/kernel"
    24  	"github.com/SagerNet/gvisor/pkg/sentry/kernel/auth"
    25  	"github.com/SagerNet/gvisor/pkg/sentry/memmap"
    26  	"github.com/SagerNet/gvisor/pkg/sentry/vfs"
    27  	"github.com/SagerNet/gvisor/pkg/syserror"
    28  	"github.com/SagerNet/gvisor/pkg/usermem"
    29  )
    30  
    31  func (fs *filesystem) newKcovFile(ctx context.Context, creds *auth.Credentials) kernfs.Inode {
    32  	k := &kcovInode{}
    33  	k.InodeAttrs.Init(ctx, creds, 0, 0, fs.NextIno(), linux.S_IFREG|0600)
    34  	return k
    35  }
    36  
    37  // kcovInode implements kernfs.Inode.
    38  //
    39  // +stateify savable
    40  type kcovInode struct {
    41  	kernfs.InodeAttrs
    42  	kernfs.InodeNoopRefCount
    43  	kernfs.InodeNotDirectory
    44  	kernfs.InodeNotSymlink
    45  	implStatFS
    46  }
    47  
    48  func (i *kcovInode) Open(ctx context.Context, rp *vfs.ResolvingPath, d *kernfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
    49  	k := kernel.KernelFromContext(ctx)
    50  	if k == nil {
    51  		panic("KernelFromContext returned nil")
    52  	}
    53  	fd := &kcovFD{
    54  		inode: i,
    55  		kcov:  k.NewKcov(),
    56  	}
    57  
    58  	if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), d.VFSDentry(), &vfs.FileDescriptionOptions{
    59  		DenyPRead:  true,
    60  		DenyPWrite: true,
    61  	}); err != nil {
    62  		return nil, err
    63  	}
    64  	return &fd.vfsfd, nil
    65  }
    66  
    67  // +stateify savable
    68  type kcovFD struct {
    69  	vfs.FileDescriptionDefaultImpl
    70  	vfs.NoLockFD
    71  
    72  	vfsfd vfs.FileDescription
    73  	inode *kcovInode
    74  	kcov  *kernel.Kcov
    75  }
    76  
    77  // Ioctl implements vfs.FileDescriptionImpl.Ioctl.
    78  func (fd *kcovFD) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) {
    79  	cmd := uint32(args[1].Int())
    80  	arg := args[2].Uint64()
    81  	switch uint32(cmd) {
    82  	case linux.KCOV_INIT_TRACE:
    83  		return 0, fd.kcov.InitTrace(arg)
    84  	case linux.KCOV_ENABLE:
    85  		return 0, fd.kcov.EnableTrace(ctx, uint8(arg))
    86  	case linux.KCOV_DISABLE:
    87  		if arg != 0 {
    88  			// This arg is unused; it should be 0.
    89  			return 0, linuxerr.EINVAL
    90  		}
    91  		return 0, fd.kcov.DisableTrace(ctx)
    92  	default:
    93  		return 0, syserror.ENOTTY
    94  	}
    95  }
    96  
    97  // ConfigureMmap implements vfs.FileDescriptionImpl.ConfigureMmap.
    98  func (fd *kcovFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
    99  	return fd.kcov.ConfigureMMap(ctx, opts)
   100  }
   101  
   102  // Release implements vfs.FileDescriptionImpl.Release.
   103  func (fd *kcovFD) Release(ctx context.Context) {
   104  	// kcov instances have reference counts in Linux, but this seems sufficient
   105  	// for our purposes.
   106  	fd.kcov.Clear(ctx)
   107  }
   108  
   109  // SetStat implements vfs.FileDescriptionImpl.SetStat.
   110  func (fd *kcovFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
   111  	creds := auth.CredentialsFromContext(ctx)
   112  	fs := fd.vfsfd.VirtualDentry().Mount().Filesystem()
   113  	return fd.inode.SetStat(ctx, fs, creds, opts)
   114  }
   115  
   116  // Stat implements vfs.FileDescriptionImpl.Stat.
   117  func (fd *kcovFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
   118  	return fd.inode.Stat(ctx, fd.vfsfd.Mount().Filesystem(), opts)
   119  }