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// Copyright 2021 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 proc
import (
"bytes"
"fmt"
"sync/atomic"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/usermem"
)
func (fs *filesystem) newYAMAPtraceScopeFile(ctx context.Context, k *kernel.Kernel, creds *auth.Credentials) kernfs.Inode {
s := &yamaPtraceScope{level: &k.YAMAPtraceScope}
s.Init(ctx, creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), s, 0644)
return s
}
// yamaPtraceScope implements vfs.WritableDynamicBytesSource for
// /sys/kernel/yama/ptrace_scope.
//
// +stateify savable
type yamaPtraceScope struct {
kernfs.DynamicBytesFile
// level is the ptrace_scope level.
level *int32
}
// Generate implements vfs.DynamicBytesSource.Generate.
func (s *yamaPtraceScope) Generate(ctx context.Context, buf *bytes.Buffer) error {
_, err := fmt.Fprintf(buf, "%d\n", atomic.LoadInt32(s.level))
return err
}
// Write implements vfs.WritableDynamicBytesSource.Write.
func (s *yamaPtraceScope) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
if offset != 0 {
// Ignore partial writes.
return 0, linuxerr.EINVAL
}
if src.NumBytes() == 0 {
return 0, nil
}
// Limit the amount of memory allocated.
src = src.TakeFirst(hostarch.PageSize - 1)
var v int32
n, err := usermem.CopyInt32StringInVec(ctx, src.IO, src.Addrs, &v, src.Opts)
if err != nil {
return 0, err
}
// We do not support YAMA levels > YAMA_SCOPE_RELATIONAL.
if v < linux.YAMA_SCOPE_DISABLED || v > linux.YAMA_SCOPE_RELATIONAL {
return 0, linuxerr.EINVAL
}
atomic.StoreInt32(s.level, v)
return n, nil
}
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