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-rw-r--r--pkg/sentry/fs/proc/BUILD1
-rw-r--r--pkg/sentry/fs/proc/sys_net.go120
-rw-r--r--pkg/sentry/fs/proc/sys_net_state.go15
-rw-r--r--pkg/sentry/fs/proc/sys_net_test.go73
4 files changed, 207 insertions, 2 deletions
diff --git a/pkg/sentry/fs/proc/BUILD b/pkg/sentry/fs/proc/BUILD
index 77c2c5c0e..b8b2281a8 100644
--- a/pkg/sentry/fs/proc/BUILD
+++ b/pkg/sentry/fs/proc/BUILD
@@ -50,6 +50,7 @@ go_library(
"//pkg/sync",
"//pkg/syserror",
"//pkg/tcpip/header",
+ "//pkg/tcpip/network/ipv4",
"//pkg/usermem",
"//pkg/waiter",
],
diff --git a/pkg/sentry/fs/proc/sys_net.go b/pkg/sentry/fs/proc/sys_net.go
index 8615b60f0..e555672ad 100644
--- a/pkg/sentry/fs/proc/sys_net.go
+++ b/pkg/sentry/fs/proc/sys_net.go
@@ -26,6 +26,7 @@ import (
"gvisor.dev/gvisor/pkg/sentry/fs/ramfs"
"gvisor.dev/gvisor/pkg/sentry/inet"
"gvisor.dev/gvisor/pkg/sync"
+ "gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
"gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
@@ -54,7 +55,7 @@ type tcpMemInode struct {
// size stores the tcp buffer size during save, and sets the buffer
// size in netstack in restore. We must save/restore this here, since
- // netstack itself is stateless.
+ // a netstack instance is created on restore.
size inet.TCPBufferSize
// mu protects against concurrent reads/writes to files based on this
@@ -258,6 +259,9 @@ func (f *tcpSackFile) Write(ctx context.Context, _ *fs.File, src usermem.IOSeque
if src.NumBytes() == 0 {
return 0, nil
}
+
+ // Only consider size of one memory page for input for performance reasons.
+ // We are only reading if it's zero or not anyway.
src = src.TakeFirst(usermem.PageSize - 1)
var v int32
@@ -383,11 +387,125 @@ func (p *proc) newSysNetCore(ctx context.Context, msrc *fs.MountSource, s inet.S
return newProcInode(ctx, d, msrc, fs.SpecialDirectory, nil)
}
+// ipForwarding implements fs.InodeOperations.
+//
+// ipForwarding is used to enable/disable packet forwarding of netstack.
+//
+// +stateify savable
+type ipForwarding struct {
+ fsutil.SimpleFileInode
+
+ stack inet.Stack `state:"wait"`
+
+ // enabled stores the IPv4 forwarding state on save.
+ // We must save/restore this here, since a netstack instance
+ // is created on restore.
+ enabled *bool
+}
+
+func newIPForwardingInode(ctx context.Context, msrc *fs.MountSource, s inet.Stack) *fs.Inode {
+ ipf := &ipForwarding{
+ SimpleFileInode: *fsutil.NewSimpleFileInode(ctx, fs.RootOwner, fs.FilePermsFromMode(0444), linux.PROC_SUPER_MAGIC),
+ stack: s,
+ }
+ sattr := fs.StableAttr{
+ DeviceID: device.ProcDevice.DeviceID(),
+ InodeID: device.ProcDevice.NextIno(),
+ BlockSize: usermem.PageSize,
+ Type: fs.SpecialFile,
+ }
+ return fs.NewInode(ctx, ipf, msrc, sattr)
+}
+
+// Truncate implements fs.InodeOperations.Truncate. Truncate is called when
+// O_TRUNC is specified for any kind of existing Dirent but is not called via
+// (f)truncate for proc files.
+func (*ipForwarding) Truncate(context.Context, *fs.Inode, int64) error {
+ return nil
+}
+
+// +stateify savable
+type ipForwardingFile struct {
+ fsutil.FileGenericSeek `state:"nosave"`
+ fsutil.FileNoIoctl `state:"nosave"`
+ fsutil.FileNoMMap `state:"nosave"`
+ fsutil.FileNoSplice `state:"nosave"`
+ fsutil.FileNoopFlush `state:"nosave"`
+ fsutil.FileNoopFsync `state:"nosave"`
+ fsutil.FileNoopRelease `state:"nosave"`
+ fsutil.FileNotDirReaddir `state:"nosave"`
+ fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+ waiter.AlwaysReady `state:"nosave"`
+
+ ipf *ipForwarding
+
+ stack inet.Stack `state:"wait"`
+}
+
+// GetFile implements fs.InodeOperations.GetFile.
+func (ipf *ipForwarding) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+ flags.Pread = true
+ flags.Pwrite = true
+ return fs.NewFile(ctx, dirent, flags, &ipForwardingFile{
+ stack: ipf.stack,
+ ipf: ipf,
+ }), nil
+}
+
+// Read implements fs.FileOperations.Read.
+func (f *ipForwardingFile) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, offset int64) (int64, error) {
+ if offset != 0 {
+ return 0, io.EOF
+ }
+
+ if f.ipf.enabled == nil {
+ enabled := f.stack.Forwarding(ipv4.ProtocolNumber)
+ f.ipf.enabled = &enabled
+ }
+
+ val := "0\n"
+ if *f.ipf.enabled {
+ // Technically, this is not quite compatible with Linux. Linux
+ // stores these as an integer, so if you write "2" into
+ // ip_forward, you should get 2 back.
+ val = "1\n"
+ }
+ n, err := dst.CopyOut(ctx, []byte(val))
+ return int64(n), err
+}
+
+// Write implements fs.FileOperations.Write.
+//
+// Offset is ignored, multiple writes are not supported.
+func (f *ipForwardingFile) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, offset int64) (int64, error) {
+ if src.NumBytes() == 0 {
+ return 0, nil
+ }
+
+ // Only consider size of one memory page for input for performance reasons.
+ // We are only reading if it's zero or not anyway.
+ src = src.TakeFirst(usermem.PageSize - 1)
+
+ var v int32
+ n, err := usermem.CopyInt32StringInVec(ctx, src.IO, src.Addrs, &v, src.Opts)
+ if err != nil {
+ return n, err
+ }
+ if f.ipf.enabled == nil {
+ f.ipf.enabled = new(bool)
+ }
+ *f.ipf.enabled = v != 0
+ return n, f.stack.SetForwarding(ipv4.ProtocolNumber, *f.ipf.enabled)
+}
+
func (p *proc) newSysNetIPv4Dir(ctx context.Context, msrc *fs.MountSource, s inet.Stack) *fs.Inode {
contents := map[string]*fs.Inode{
// Add tcp_sack.
"tcp_sack": newTCPSackInode(ctx, msrc, s),
+ // Add ip_forward.
+ "ip_forward": newIPForwardingInode(ctx, msrc, s),
+
// The following files are simple stubs until they are
// implemented in netstack, most of these files are
// configuration related. We use the value closest to the
diff --git a/pkg/sentry/fs/proc/sys_net_state.go b/pkg/sentry/fs/proc/sys_net_state.go
index 6eba709c6..4cb4741af 100644
--- a/pkg/sentry/fs/proc/sys_net_state.go
+++ b/pkg/sentry/fs/proc/sys_net_state.go
@@ -14,7 +14,11 @@
package proc
-import "fmt"
+import (
+ "fmt"
+
+ "gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
+)
// beforeSave is invoked by stateify.
func (t *tcpMemInode) beforeSave() {
@@ -40,3 +44,12 @@ func (s *tcpSack) afterLoad() {
}
}
}
+
+// afterLoad is invoked by stateify.
+func (ipf *ipForwarding) afterLoad() {
+ if ipf.enabled != nil {
+ if err := ipf.stack.SetForwarding(ipv4.ProtocolNumber, *ipf.enabled); err != nil {
+ panic(fmt.Sprintf("failed to set IPv4 forwarding [%v]: %v", *ipf.enabled, err))
+ }
+ }
+}
diff --git a/pkg/sentry/fs/proc/sys_net_test.go b/pkg/sentry/fs/proc/sys_net_test.go
index 355e83d47..6ef5738e7 100644
--- a/pkg/sentry/fs/proc/sys_net_test.go
+++ b/pkg/sentry/fs/proc/sys_net_test.go
@@ -123,3 +123,76 @@ func TestConfigureRecvBufferSize(t *testing.T) {
}
}
}
+
+// TestIPForwarding tests the implementation of
+// /proc/sys/net/ipv4/ip_forwarding
+func TestIPForwarding(t *testing.T) {
+ ctx := context.Background()
+ s := inet.NewTestStack()
+
+ var cases = []struct {
+ comment string
+ initial bool
+ str string
+ final bool
+ }{
+ {
+ comment: `Forwarding is disabled; write 1 and enable forwarding`,
+ initial: false,
+ str: "1",
+ final: true,
+ },
+ {
+ comment: `Forwarding is disabled; write 0 and disable forwarding`,
+ initial: false,
+ str: "0",
+ final: false,
+ },
+ {
+ comment: `Forwarding is enabled; write 1 and enable forwarding`,
+ initial: true,
+ str: "1",
+ final: true,
+ },
+ {
+ comment: `Forwarding is enabled; write 0 and disable forwarding`,
+ initial: true,
+ str: "0",
+ final: false,
+ },
+ {
+ comment: `Forwarding is disabled; write 2404 and enable forwarding`,
+ initial: false,
+ str: "2404",
+ final: true,
+ },
+ {
+ comment: `Forwarding is enabled; write 2404 and enable forwarding`,
+ initial: true,
+ str: "2404",
+ final: true,
+ },
+ }
+ for _, c := range cases {
+ t.Run(c.comment, func(t *testing.T) {
+ s.IPForwarding = c.initial
+ ipf := &ipForwarding{stack: s}
+ file := &ipForwardingFile{
+ stack: s,
+ ipf: ipf,
+ }
+
+ // Write the values.
+ src := usermem.BytesIOSequence([]byte(c.str))
+ if n, err := file.Write(ctx, nil, src, 0); n != int64(len(c.str)) || err != nil {
+ t.Errorf("file.Write(ctx, nil, %q, 0) = (%d, %v); want (%d, nil)", c.str, n, err, len(c.str))
+ }
+
+ // Read the values from the stack and check them.
+ if got, want := s.IPForwarding, c.final; got != want {
+ t.Errorf("s.IPForwarding incorrect; got: %v, want: %v", got, want)
+ }
+
+ })
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-17 17:23:23 +0000