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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sys
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/memmap"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
func (fs *filesystem) newKcovFile(ctx context.Context, creds *auth.Credentials) *kernfs.Dentry {
k := &kcovInode{}
k.InodeAttrs.Init(creds, 0, 0, fs.NextIno(), linux.S_IFREG|0600)
d := &kernfs.Dentry{}
d.Init(k)
return d
}
// kcovInode implements kernfs.Inode.
type kcovInode struct {
kernfs.InodeAttrs
kernfs.InodeNoopRefCount
kernfs.InodeNotDirectory
kernfs.InodeNotSymlink
implStatFS
}
func (i *kcovInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
k := kernel.KernelFromContext(ctx)
if k == nil {
panic("KernelFromContext returned nil")
}
fd := &kcovFD{
inode: i,
kcov: k.NewKcov(),
}
if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{
DenyPRead: true,
DenyPWrite: true,
}); err != nil {
return nil, err
}
return &fd.vfsfd, nil
}
type kcovFD struct {
vfs.FileDescriptionDefaultImpl
vfs.NoLockFD
vfsfd vfs.FileDescription
inode *kcovInode
kcov *kernel.Kcov
}
// Ioctl implements vfs.FileDescriptionImpl.Ioctl.
func (fd *kcovFD) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) {
cmd := uint32(args[1].Int())
arg := args[2].Uint64()
switch uint32(cmd) {
case linux.KCOV_INIT_TRACE:
return 0, fd.kcov.InitTrace(arg)
case linux.KCOV_ENABLE:
return 0, fd.kcov.EnableTrace(ctx, uint8(arg))
case linux.KCOV_DISABLE:
if arg != 0 {
// This arg is unused; it should be 0.
return 0, syserror.EINVAL
}
return 0, fd.kcov.DisableTrace(ctx)
default:
return 0, syserror.ENOTTY
}
}
// ConfigureMmap implements vfs.FileDescriptionImpl.ConfigureMmap.
func (fd *kcovFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return fd.kcov.ConfigureMMap(ctx, opts)
}
// Release implements vfs.FileDescriptionImpl.Release.
func (fd *kcovFD) Release(ctx context.Context) {
// kcov instances have reference counts in Linux, but this seems sufficient
// for our purposes.
fd.kcov.Reset()
}
// SetStat implements vfs.FileDescriptionImpl.SetStat.
func (fd *kcovFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
creds := auth.CredentialsFromContext(ctx)
fs := fd.vfsfd.VirtualDentry().Mount().Filesystem()
return fd.inode.SetStat(ctx, fs, creds, opts)
}
// Stat implements vfs.FileDescriptionImpl.Stat.
func (fd *kcovFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
return fd.inode.Stat(ctx, fd.vfsfd.Mount().Filesystem(), opts)
}
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