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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 host
import (
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/socket/control"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
type scmRights struct {
fds []int
}
func newSCMRights(fds []int) control.SCMRightsVFS2 {
return &scmRights{fds}
}
// Files implements control.SCMRights.Files.
func (c *scmRights) Files(ctx context.Context, max int) (control.RightsFilesVFS2, bool) {
n := max
var trunc bool
if l := len(c.fds); n > l {
n = l
} else if n < l {
trunc = true
}
rf := control.RightsFilesVFS2(fdsToFiles(ctx, c.fds[:n]))
// Only consume converted FDs (fdsToFiles may convert fewer than n FDs).
c.fds = c.fds[len(rf):]
return rf, trunc
}
// Clone implements transport.RightsControlMessage.Clone.
func (c *scmRights) Clone() transport.RightsControlMessage {
// Host rights never need to be cloned.
return nil
}
// Release implements transport.RightsControlMessage.Release.
func (c *scmRights) Release(ctx context.Context) {
for _, fd := range c.fds {
syscall.Close(fd)
}
c.fds = nil
}
// If an error is encountered, only files created before the error will be
// returned. This is what Linux does.
func fdsToFiles(ctx context.Context, fds []int) []*vfs.FileDescription {
files := make([]*vfs.FileDescription, 0, len(fds))
for _, fd := range fds {
// Get flags. We do it here because they may be modified
// by subsequent functions.
fileFlags, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_GETFL, 0)
if errno != 0 {
ctx.Warningf("Error retrieving host FD flags: %v", error(errno))
break
}
// Create the file backed by hostFD.
file, err := NewFD(ctx, kernel.KernelFromContext(ctx).HostMount(), fd, &NewFDOptions{})
if err != nil {
ctx.Warningf("Error creating file from host FD: %v", err)
break
}
if err := file.SetStatusFlags(ctx, auth.CredentialsFromContext(ctx), uint32(fileFlags&linux.O_NONBLOCK)); err != nil {
ctx.Warningf("Error setting flags on host FD file: %v", err)
break
}
files = append(files, file)
}
return files
}
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