Implement pipe(2) and pipe2(2) for VFS2.

Updates #1035

PiperOrigin-RevId: 306968644

6 files changed, 99 insertions, 10 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_pipe.go b/pkg/sentry/syscalls/linux/sys_pipe.go
index 798344042..43c510930 100644
--- a/pkg/sentry/syscalls/linux/sys_pipe.go
+++ b/pkg/sentry/syscalls/linux/sys_pipe.go
@@ -24,6 +24,8 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
+// LINT.IfChange
+
 // pipe2 implements the actual system call with flags.
 func pipe2(t *kernel.Task, addr usermem.Addr, flags uint) (uintptr, error) {
 	if flags&^(linux.O_NONBLOCK|linux.O_CLOEXEC) != 0 {
@@ -45,10 +47,12 @@ func pipe2(t *kernel.Task, addr usermem.Addr, flags uint) (uintptr, error) {
 	}
 
 	if _, err := t.CopyOut(addr, fds); err != nil {
-		// The files are not closed in this case, the exact semantics
-		// of this error case are not well defined, but they could have
-		// already been observed by user space.
-		return 0, syserror.EFAULT
+		for _, fd := range fds {
+			if file, _ := t.FDTable().Remove(fd); file != nil {
+				file.DecRef()
+			}
+		}
+		return 0, err
 	}
 	return 0, nil
 }
@@ -69,3 +73,5 @@ func Pipe2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	n, err := pipe2(t, addr, flags)
 	return n, nil, err
 }
+
+// LINT.ThenChange(vfs2/pipe.go)
diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
index b32abfe59..6ff2d84d2 100644
--- a/pkg/sentry/syscalls/linux/vfs2/BUILD
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -18,6 +18,7 @@ go_library(
         "linux64_override_arm64.go",
         "mmap.go",
         "path.go",
+        "pipe.go",
         "poll.go",
         "read_write.go",
         "setstat.go",
@@ -39,8 +40,10 @@ go_library(
         "//pkg/gohacks",
         "//pkg/sentry/arch",
         "//pkg/sentry/fsbridge",
+        "//pkg/sentry/fsimpl/pipefs",
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",
+        "//pkg/sentry/kernel/pipe",
         "//pkg/sentry/kernel/time",
         "//pkg/sentry/limits",
         "//pkg/sentry/loader",
diff --git a/pkg/sentry/syscalls/linux/vfs2/fd.go b/pkg/sentry/syscalls/linux/vfs2/fd.go
index 3afcea665..8181d80f4 100644
--- a/pkg/sentry/syscalls/linux/vfs2/fd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/fd.go
@@ -18,6 +18,7 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/pipe"
 	slinux "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
@@ -140,6 +141,22 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 		return uintptr(file.StatusFlags()), nil, nil
 	case linux.F_SETFL:
 		return 0, nil, file.SetStatusFlags(t, t.Credentials(), args[2].Uint())
+	case linux.F_SETPIPE_SZ:
+		pipefile, ok := file.Impl().(*pipe.VFSPipeFD)
+		if !ok {
+			return 0, nil, syserror.EBADF
+		}
+		n, err := pipefile.SetPipeSize(int64(args[2].Int()))
+		if err != nil {
+			return 0, nil, err
+		}
+		return uintptr(n), nil, nil
+	case linux.F_GETPIPE_SZ:
+		pipefile, ok := file.Impl().(*pipe.VFSPipeFD)
+		if !ok {
+			return 0, nil, syserror.EBADF
+		}
+		return uintptr(pipefile.PipeSize()), nil, nil
 	default:
 		// TODO(gvisor.dev/issue/1623): Everything else is not yet supported.
 		return 0, nil, syserror.EINVAL
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
index 645e0bcb8..21eb98444 100644
--- a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
@@ -39,7 +39,7 @@ func Override(table map[uintptr]kernel.Syscall) {
 	table[19] = syscalls.Supported("readv", Readv)
 	table[20] = syscalls.Supported("writev", Writev)
 	table[21] = syscalls.Supported("access", Access)
-	delete(table, 22) // pipe
+	table[22] = syscalls.Supported("pipe", Pipe)
 	table[23] = syscalls.Supported("select", Select)
 	table[32] = syscalls.Supported("dup", Dup)
 	table[33] = syscalls.Supported("dup2", Dup2)
@@ -151,7 +151,7 @@ func Override(table map[uintptr]kernel.Syscall) {
 	delete(table, 290) // eventfd2
 	table[291] = syscalls.Supported("epoll_create1", EpollCreate1)
 	table[292] = syscalls.Supported("dup3", Dup3)
-	delete(table, 293) // pipe2
+	table[293] = syscalls.Supported("pipe2", Pipe2)
 	delete(table, 294) // inotify_init1
 	table[295] = syscalls.Supported("preadv", Preadv)
 	table[296] = syscalls.Supported("pwritev", Pwritev)
diff --git a/pkg/sentry/syscalls/linux/vfs2/pipe.go b/pkg/sentry/syscalls/linux/vfs2/pipe.go
new file mode 100644
index 000000000..4a01e4209
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/pipe.go
@@ -0,0 +1,63 @@
+// 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 vfs2
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/pipefs"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+// Pipe implements Linux syscall pipe(2).
+func Pipe(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	return 0, nil, pipe2(t, addr, 0)
+}
+
+// Pipe2 implements Linux syscall pipe2(2).
+func Pipe2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	flags := args[1].Int()
+	return 0, nil, pipe2(t, addr, flags)
+}
+
+func pipe2(t *kernel.Task, addr usermem.Addr, flags int32) error {
+	if flags&^(linux.O_NONBLOCK|linux.O_CLOEXEC) != 0 {
+		return syserror.EINVAL
+	}
+	r, w := pipefs.NewConnectedPipeFDs(t, t.Kernel().PipeMount(), uint32(flags&linux.O_NONBLOCK))
+	defer r.DecRef()
+	defer w.DecRef()
+
+	fds, err := t.NewFDsVFS2(0, []*vfs.FileDescription{r, w}, kernel.FDFlags{
+		CloseOnExec: flags&linux.O_CLOEXEC != 0,
+	})
+	if err != nil {
+		return err
+	}
+	if _, err := t.CopyOut(addr, fds); err != nil {
+		for _, fd := range fds {
+			if _, file := t.FDTable().Remove(fd); file != nil {
+				file.DecRef()
+			}
+		}
+		return err
+	}
+	return nil
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/read_write.go b/pkg/sentry/syscalls/linux/vfs2/read_write.go
index 898b190fd..6c6998f45 100644
--- a/pkg/sentry/syscalls/linux/vfs2/read_write.go
+++ b/pkg/sentry/syscalls/linux/vfs2/read_write.go
@@ -103,7 +103,7 @@ func read(t *kernel.Task, file *vfs.FileDescription, dst usermem.IOSequence, opt
 
 		// Issue the request and break out if it completes with anything other than
 		// "would block".
-		n, err := file.Read(t, dst, opts)
+		n, err = file.Read(t, dst, opts)
 		total += n
 		if err != syserror.ErrWouldBlock {
 			break
@@ -248,7 +248,7 @@ func pread(t *kernel.Task, file *vfs.FileDescription, dst usermem.IOSequence, of
 
 		// Issue the request and break out if it completes with anything other than
 		// "would block".
-		n, err := file.PRead(t, dst, offset+total, opts)
+		n, err = file.PRead(t, dst, offset+total, opts)
 		total += n
 		if err != syserror.ErrWouldBlock {
 			break
@@ -335,7 +335,7 @@ func write(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, op
 
 		// Issue the request and break out if it completes with anything other than
 		// "would block".
-		n, err := file.Write(t, src, opts)
+		n, err = file.Write(t, src, opts)
 		total += n
 		if err != syserror.ErrWouldBlock {
 			break
@@ -480,7 +480,7 @@ func pwrite(t *kernel.Task, file *vfs.FileDescription, src usermem.IOSequence, o
 
 		// Issue the request and break out if it completes with anything other than
 		// "would block".
-		n, err := file.PWrite(t, src, offset+total, opts)
+		n, err = file.PWrite(t, src, offset+total, opts)
 		total += n
 		if err != syserror.ErrWouldBlock {
 			break