Implement sysv shm.

PiperOrigin-RevId: 197058289
Change-Id: I3946c25028b7e032be4894d61acb48ac0c24d574

3 files changed, 161 insertions, 4 deletions

diff --git a/pkg/sentry/syscalls/linux/BUILD b/pkg/sentry/syscalls/linux/BUILD
index bc67ebf30..f9e0a4be3 100644
--- a/pkg/sentry/syscalls/linux/BUILD
+++ b/pkg/sentry/syscalls/linux/BUILD
@@ -44,6 +44,7 @@ go_library(
         "sys_rusage.go",
         "sys_sched.go",
         "sys_sem.go",
+        "sys_shm.go",
         "sys_signal.go",
         "sys_socket.go",
         "sys_stat.go",
@@ -84,6 +85,7 @@ go_library(
         "//pkg/sentry/kernel/pipe",
         "//pkg/sentry/kernel/sched",
         "//pkg/sentry/kernel/semaphore",
+        "//pkg/sentry/kernel/shm",
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/limits",
         "//pkg/sentry/memmap",
diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go
index 44db2d582..237c61007 100644
--- a/pkg/sentry/syscalls/linux/linux64.go
+++ b/pkg/sentry/syscalls/linux/linux64.go
@@ -75,9 +75,9 @@ var AMD64 = &kernel.SyscallTable{
 		26: Msync,
 		27: Mincore,
 		28: Madvise,
-		//     29: Shmget, TODO
-		//     30: Shmat, TODO
-		//     31: Shmctl, TODO
+		29: Shmget,
+		30: Shmat,
+		31: Shmctl,
 		32: Dup,
 		33: Dup2,
 		34: Pause,
@@ -113,7 +113,7 @@ var AMD64 = &kernel.SyscallTable{
 		64: Semget,
 		65: Semop,
 		66: Semctl,
-		//     67: Shmdt, TODO
+		67: Shmdt,
 		//     68: Msgget, TODO
 		//     69: Msgsnd, TODO
 		//     70: Msgrcv, TODO
diff --git a/pkg/sentry/syscalls/linux/sys_shm.go b/pkg/sentry/syscalls/linux/sys_shm.go
new file mode 100644
index 000000000..48ff1d5f0
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/sys_shm.go
@@ -0,0 +1,155 @@
+// 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 (
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/shm"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+)
+
+// Shmget implements shmget(2).
+func Shmget(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	key := args[0].Int()
+	size := uint64(args[1].SizeT())
+	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)
+
+	pid := int32(t.ThreadGroup().ID())
+	r := t.IPCNamespace().ShmRegistry()
+	segment, err := r.FindOrCreate(t, pid, key, size, mode, private, create, exclusive)
+	if err != nil {
+		return 0, nil, err
+	}
+	return uintptr(segment.ID), nil, nil
+}
+
+// findSegment retrives a shm segment by the given id.
+func findSegment(t *kernel.Task, id int32) (*shm.Shm, error) {
+	r := t.IPCNamespace().ShmRegistry()
+	segment := r.FindByID(id)
+	if segment == nil {
+		// No segment with provided id.
+		return nil, syserror.EINVAL
+	}
+	return segment, nil
+}
+
+// Shmat implements shmat(2).
+func Shmat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	id := args[0].Int()
+	addr := args[1].Pointer()
+	flag := args[2].Int()
+
+	segment, err := findSegment(t, id)
+	if err != nil {
+		return 0, nil, syserror.EINVAL
+	}
+
+	opts, err := segment.ConfigureAttach(t, addr, shm.AttachOpts{
+		Execute:  flag&linux.SHM_EXEC == linux.SHM_EXEC,
+		Readonly: flag&linux.SHM_RDONLY == linux.SHM_RDONLY,
+		Remap:    flag&linux.SHM_REMAP == linux.SHM_REMAP,
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+	defer segment.DecRef()
+	addr, err = t.MemoryManager().MMap(t, opts)
+	return uintptr(addr), nil, err
+}
+
+// Shmdt implements shmdt(2).
+func Shmdt(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	err := t.MemoryManager().DetachShm(t, addr)
+	return 0, nil, err
+}
+
+// Shmctl implements shmctl(2).
+func Shmctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	id := args[0].Int()
+	cmd := args[1].Int()
+	buf := args[2].Pointer()
+
+	r := t.IPCNamespace().ShmRegistry()
+
+	switch cmd {
+	case linux.SHM_STAT:
+		// Technically, we should be treating id as "an index into the kernel's
+		// internal array that maintains information about all shared memory
+		// segments on the system". Since we don't track segments in an array,
+		// we'll just pretend the shmid is the index and do the same thing as
+		// IPC_STAT. Linux also uses the index as the shmid.
+		fallthrough
+	case linux.IPC_STAT:
+		segment, err := findSegment(t, id)
+		if err != nil {
+			return 0, nil, syserror.EINVAL
+		}
+
+		stat, err := segment.IPCStat(t)
+		if err == nil {
+			_, err = t.CopyOut(buf, stat)
+		}
+		return 0, nil, err
+
+	case linux.IPC_INFO:
+		params := r.IPCInfo()
+		_, err := t.CopyOut(buf, params)
+		return 0, nil, err
+
+	case linux.SHM_INFO:
+		info := r.ShmInfo()
+		_, err := t.CopyOut(buf, info)
+		return 0, nil, err
+	}
+
+	// Remaining commands refer to a specific segment.
+	segment, err := findSegment(t, id)
+	if err != nil {
+		return 0, nil, syserror.EINVAL
+	}
+
+	switch cmd {
+	case linux.IPC_SET:
+		var ds linux.ShmidDS
+		_, err = t.CopyIn(buf, &ds)
+		if err != nil {
+			return 0, nil, err
+		}
+		err = segment.Set(t, &ds)
+		return 0, nil, err
+
+	case linux.IPC_RMID:
+		segment.MarkDestroyed()
+		return 0, nil, nil
+
+	case linux.SHM_LOCK, linux.SHM_UNLOCK:
+		// We currently do not support memmory locking anywhere.
+		// mlock(2)/munlock(2) are currently stubbed out as no-ops so do the
+		// same here.
+		return 0, nil, nil
+
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+}