Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 166 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_sem.go b/pkg/sentry/syscalls/linux/sys_sem.go
new file mode 100644
index 000000000..a8983705b
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/sys_sem.go
@@ -0,0 +1,166 @@
+// Copyright 2018 Google Inc.
+//
+// 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 (
+	"math"
+
+	"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/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+)
+
+const opsMax = 500 // SEMOPM
+
+// Semget handles: semget(key_t key, int nsems, int semflg)
+func Semget(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	key := args[0].Int()
+	nsems := args[1].Int()
+	flag := args[2].Int()
+
+	private := key == linux.IPC_PRIVATE
+	create := flag&linux.IPC_CREAT == linux.IPC_CREAT
+	exclusive := flag&linux.IPC_EXCL == linux.IPC_EXCL
+	mode := linux.FileMode(flag & 0777)
+
+	r := t.IPCNamespace().SemaphoreRegistry()
+	set, err := r.FindOrCreate(t, key, nsems, mode, private, create, exclusive)
+	if err != nil {
+		return 0, nil, err
+	}
+	return uintptr(set.ID), nil, nil
+}
+
+// Semop handles: semop(int semid, struct sembuf *sops, size_t nsops)
+func Semop(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	id := args[0].Int()
+	sembufAddr := args[1].Pointer()
+	nsops := args[2].SizeT()
+
+	r := t.IPCNamespace().SemaphoreRegistry()
+	set := r.FindByID(id)
+	if set == nil {
+		return 0, nil, syserror.EINVAL
+	}
+	if nsops <= 0 {
+		return 0, nil, syserror.EINVAL
+	}
+	if nsops > opsMax {
+		return 0, nil, syserror.E2BIG
+	}
+
+	ops := make([]linux.Sembuf, nsops)
+	if _, err := t.CopyIn(sembufAddr, ops); err != nil {
+		return 0, nil, err
+	}
+
+	creds := auth.CredentialsFromContext(t)
+	for {
+		ch, num, err := set.ExecuteOps(t, ops, creds)
+		if ch == nil || err != nil {
+			// We're done (either on success or a failure).
+			return 0, nil, err
+		}
+		if err = t.Block(ch); err != nil {
+			set.AbortWait(num, ch)
+			return 0, nil, err
+		}
+	}
+}
+
+// Semctl handles: semctl(int semid, int semnum, int cmd, ...)
+func Semctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	id := args[0].Int()
+	num := args[1].Int()
+	cmd := args[2].Int()
+
+	switch cmd {
+	case linux.SETVAL:
+		val := args[3].Int()
+		if val > math.MaxInt16 {
+			return 0, nil, syserror.ERANGE
+		}
+		return 0, nil, setVal(t, id, num, int16(val))
+
+	case linux.GETVAL:
+		v, err := getVal(t, id, num)
+		return uintptr(v), nil, err
+
+	case linux.IPC_RMID:
+		return 0, nil, remove(t, id)
+
+	case linux.IPC_SET:
+		arg := args[3].Pointer()
+		s := linux.SemidDS{}
+		if _, err := t.CopyIn(arg, &s); err != nil {
+			return 0, nil, err
+		}
+
+		perms := fs.FilePermsFromMode(linux.FileMode(s.SemPerm.Mode & 0777))
+		return 0, nil, ipcSet(t, id, auth.UID(s.SemPerm.UID), auth.GID(s.SemPerm.GID), perms)
+
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+}
+
+func remove(t *kernel.Task, id int32) error {
+	r := t.IPCNamespace().SemaphoreRegistry()
+	creds := auth.CredentialsFromContext(t)
+	return r.RemoveID(id, creds)
+}
+
+func ipcSet(t *kernel.Task, id int32, uid auth.UID, gid auth.GID, perms fs.FilePermissions) error {
+	r := t.IPCNamespace().SemaphoreRegistry()
+	set := r.FindByID(id)
+	if set == nil {
+		return syserror.EINVAL
+	}
+
+	creds := auth.CredentialsFromContext(t)
+	kuid := creds.UserNamespace.MapToKUID(uid)
+	if !kuid.Ok() {
+		return syserror.EINVAL
+	}
+	kgid := creds.UserNamespace.MapToKGID(gid)
+	if !kgid.Ok() {
+		return syserror.EINVAL
+	}
+	owner := fs.FileOwner{UID: kuid, GID: kgid}
+	return set.Change(t, creds, owner, perms)
+}
+
+func setVal(t *kernel.Task, id int32, num int32, val int16) error {
+	r := t.IPCNamespace().SemaphoreRegistry()
+	set := r.FindByID(id)
+	if set == nil {
+		return syserror.EINVAL
+	}
+	creds := auth.CredentialsFromContext(t)
+	return set.SetVal(t, num, val, creds)
+}
+
+func getVal(t *kernel.Task, id int32, num int32) (int16, error) {
+	r := t.IPCNamespace().SemaphoreRegistry()
+	set := r.FindByID(id)
+	if set == nil {
+		return 0, syserror.EINVAL
+	}
+	creds := auth.CredentialsFromContext(t)
+	return set.GetVal(num, creds)
+}