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// Copyright 2018 Google LLC
//
// 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 linux
import (
"syscall"
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/anon"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
)
const allFlags = int(linux.IN_NONBLOCK | linux.IN_CLOEXEC)
// InotifyInit1 implements the inotify_init1() syscalls.
func InotifyInit1(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
flags := int(args[0].Int())
if flags&^allFlags != 0 {
return 0, nil, syscall.EINVAL
}
dirent := fs.NewDirent(anon.NewInode(t), "inotify")
fileFlags := fs.FileFlags{
Read: true,
Write: true,
NonBlocking: flags&linux.IN_NONBLOCK != 0,
}
n := fs.NewFile(t, dirent, fileFlags, fs.NewInotify(t))
defer n.DecRef()
fd, err := t.FDMap().NewFDFrom(0, n, kernel.FDFlags{
CloseOnExec: flags&linux.IN_CLOEXEC != 0,
}, t.ThreadGroup().Limits())
if err != nil {
return 0, nil, err
}
return uintptr(fd), nil, nil
}
// InotifyInit implements the inotify_init() syscalls.
func InotifyInit(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
args[0].Value = 0
return InotifyInit1(t, args)
}
// fdToInotify resolves an fd to an inotify object. If successful, the file will
// have an extra ref and the caller is responsible for releasing the ref.
func fdToInotify(t *kernel.Task, fd kdefs.FD) (*fs.Inotify, *fs.File, error) {
file := t.FDMap().GetFile(fd)
if file == nil {
// Invalid fd.
return nil, nil, syscall.EBADF
}
ino, ok := file.FileOperations.(*fs.Inotify)
if !ok {
// Not an inotify fd.
file.DecRef()
return nil, nil, syscall.EINVAL
}
return ino, file, nil
}
// InotifyAddWatch implements the inotify_add_watch() syscall.
func InotifyAddWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := kdefs.FD(args[0].Int())
addr := args[1].Pointer()
mask := args[2].Uint()
// "IN_DONT_FOLLOW: Don't dereference pathname if it is a symbolic link."
// -- inotify(7)
resolve := mask&linux.IN_DONT_FOLLOW == 0
// "EINVAL: The given event mask contains no valid events."
// -- inotify_add_watch(2)
if validBits := mask & linux.ALL_INOTIFY_BITS; validBits == 0 {
return 0, nil, syscall.EINVAL
}
ino, file, err := fdToInotify(t, fd)
if err != nil {
return 0, nil, err
}
defer file.DecRef()
path, _, err := copyInPath(t, addr, false /* allowEmpty */)
if err != nil {
return 0, nil, err
}
err = fileOpOn(t, linux.AT_FDCWD, path, resolve, func(root *fs.Dirent, dirent *fs.Dirent) error {
// "IN_ONLYDIR: Only watch pathname if it is a directory." -- inotify(7)
if onlyDir := mask&linux.IN_ONLYDIR != 0; onlyDir && !fs.IsDir(dirent.Inode.StableAttr) {
return syscall.ENOTDIR
}
// Copy out to the return frame.
fd = kdefs.FD(ino.AddWatch(dirent, mask))
return nil
})
return uintptr(fd), nil, err // Return from the existing value.
}
// InotifyRmWatch implements the inotify_rm_watch() syscall.
func InotifyRmWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := kdefs.FD(args[0].Int())
wd := args[1].Int()
ino, file, err := fdToInotify(t, fd)
if err != nil {
return 0, nil, err
}
defer file.DecRef()
return 0, nil, ino.RmWatch(wd)
}
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