diff options
| -rw-r--r-- | pkg/sentry/fsimpl/proc/BUILD | 1 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/proc/tasks_sys.go | 110 |
2 files changed, 106 insertions, 5 deletions
diff --git a/pkg/sentry/fsimpl/proc/BUILD b/pkg/sentry/fsimpl/proc/BUILD index 6014138ff..14ecfd300 100644 --- a/pkg/sentry/fsimpl/proc/BUILD +++ b/pkg/sentry/fsimpl/proc/BUILD @@ -36,6 +36,7 @@ go_library( "//pkg/sentry/socket/unix/transport", "//pkg/sentry/usage", "//pkg/sentry/vfs", + "//pkg/sync", "//pkg/syserror", "//pkg/tcpip/header", "//pkg/usermem", diff --git a/pkg/sentry/fsimpl/proc/tasks_sys.go b/pkg/sentry/fsimpl/proc/tasks_sys.go index b71778128..6435385ef 100644 --- a/pkg/sentry/fsimpl/proc/tasks_sys.go +++ b/pkg/sentry/fsimpl/proc/tasks_sys.go @@ -25,10 +25,18 @@ import ( "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/usermem" ) +type tcpMemDir int + +const ( + tcpRMem tcpMemDir = iota + tcpWMem +) + // newSysDir returns the dentry corresponding to /proc/sys directory. func (fs *filesystem) newSysDir(root *auth.Credentials, k *kernel.Kernel) *kernfs.Dentry { return kernfs.NewStaticDir(root, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), 0555, map[string]*kernfs.Dentry{ @@ -56,7 +64,9 @@ func (fs *filesystem) newSysNetDir(root *auth.Credentials, k *kernel.Kernel) *ke contents = map[string]*kernfs.Dentry{ "ipv4": kernfs.NewStaticDir(root, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), 0555, map[string]*kernfs.Dentry{ "tcp_recovery": fs.newDentry(root, fs.NextIno(), 0644, &tcpRecoveryData{stack: stack}), + "tcp_rmem": fs.newDentry(root, fs.NextIno(), 0644, &tcpMemData{stack: stack, dir: tcpRMem}), "tcp_sack": fs.newDentry(root, fs.NextIno(), 0644, &tcpSackData{stack: stack}), + "tcp_wmem": fs.newDentry(root, fs.NextIno(), 0644, &tcpMemData{stack: stack, dir: tcpWMem}), // The following files are simple stubs until they are implemented in // netstack, most of these files are configuration related. We use the @@ -181,10 +191,11 @@ func (d *tcpSackData) Generate(ctx context.Context, buf *bytes.Buffer) error { // Tough luck. val = "1\n" } - buf.WriteString(val) - return nil + _, err := buf.WriteString(val) + return err } +// Write implements vfs.WritableDynamicBytesSource.Write. func (d *tcpSackData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) { if offset != 0 { // No need to handle partial writes thus far. @@ -200,7 +211,7 @@ func (d *tcpSackData) Write(ctx context.Context, src usermem.IOSequence, offset var v int32 n, err := usermem.CopyInt32StringInVec(ctx, src.IO, src.Addrs, &v, src.Opts) if err != nil { - return n, err + return 0, err } if d.enabled == nil { d.enabled = new(bool) @@ -228,10 +239,11 @@ func (d *tcpRecoveryData) Generate(ctx context.Context, buf *bytes.Buffer) error return err } - buf.WriteString(fmt.Sprintf("%d\n", recovery)) - return nil + _, err = buf.WriteString(fmt.Sprintf("%d\n", recovery)) + return err } +// Write implements vfs.WritableDynamicBytesSource.Write. func (d *tcpRecoveryData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) { if offset != 0 { // No need to handle partial writes thus far. @@ -254,3 +266,91 @@ func (d *tcpRecoveryData) Write(ctx context.Context, src usermem.IOSequence, off } return n, nil } + +// tcpMemData implements vfs.WritableDynamicBytesSource for +// /proc/sys/net/ipv4/tcp_rmem and /proc/sys/net/ipv4/tcp_wmem. +// +// +stateify savable +type tcpMemData struct { + kernfs.DynamicBytesFile + + dir tcpMemDir + stack inet.Stack `state:"wait"` + + // mu protects against concurrent reads/writes to FDs based on the dentry + // backing this byte source. + mu sync.Mutex `state:"nosave"` +} + +var _ vfs.WritableDynamicBytesSource = (*tcpMemData)(nil) + +// Generate implements vfs.DynamicBytesSource. +func (d *tcpMemData) Generate(ctx context.Context, buf *bytes.Buffer) error { + d.mu.Lock() + defer d.mu.Unlock() + + size, err := d.readSizeLocked() + if err != nil { + return err + } + _, err = buf.WriteString(fmt.Sprintf("%d\t%d\t%d\n", size.Min, size.Default, size.Max)) + return err +} + +// Write implements vfs.WritableDynamicBytesSource.Write. +func (d *tcpMemData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) { + if offset != 0 { + // No need to handle partial writes thus far. + return 0, syserror.EINVAL + } + if src.NumBytes() == 0 { + return 0, nil + } + d.mu.Lock() + defer d.mu.Unlock() + + // Limit the amount of memory allocated. + src = src.TakeFirst(usermem.PageSize - 1) + size, err := d.readSizeLocked() + if err != nil { + return 0, err + } + buf := []int32{int32(size.Min), int32(size.Default), int32(size.Max)} + n, err := usermem.CopyInt32StringsInVec(ctx, src.IO, src.Addrs, buf, src.Opts) + if err != nil { + return 0, err + } + newSize := inet.TCPBufferSize{ + Min: int(buf[0]), + Default: int(buf[1]), + Max: int(buf[2]), + } + if err := d.writeSizeLocked(newSize); err != nil { + return 0, err + } + return n, nil +} + +// Precondition: d.mu must be locked. +func (d *tcpMemData) readSizeLocked() (inet.TCPBufferSize, error) { + switch d.dir { + case tcpRMem: + return d.stack.TCPReceiveBufferSize() + case tcpWMem: + return d.stack.TCPSendBufferSize() + default: + panic(fmt.Sprintf("unknown tcpMemFile type: %v", d.dir)) + } +} + +// Precondition: d.mu must be locked. +func (d *tcpMemData) writeSizeLocked(size inet.TCPBufferSize) error { + switch d.dir { + case tcpRMem: + return d.stack.SetTCPReceiveBufferSize(size) + case tcpWMem: + return d.stack.SetTCPSendBufferSize(size) + default: + panic(fmt.Sprintf("unknown tcpMemFile type: %v", d.dir)) + } +} |