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Do not hold transport.Endpoint.mu during mknod in unix bind implementations.

Browse Source 
This is consistent with Linux, which calls mknod(), then takes
unix_sock::bindlock and then marks the socket as bound. On error, the mknod is
reverted. See net/unix/af_unix.c:unix_bind_bsd().

This helps break the following lock chain: kernfs.filesystemRWMutex ->
kernel.taskSetRWMutex -> mm.activeRWMutex -> transport.endpointMutex.

PiperOrigin-RevId: 442104624
This commit is contained in:
Ayush Ranjan
2022-04-15 15:07:53 -07:00
committed by gVisor bot
parent 577cf52383
commit fed9f8ee8e
7 changed files with 133 additions and 123 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pkg/sentry/socket/netlink/socket.go
+1 -1
View File
@@ -138,7 +138,7 @@ func NewSocket(t *kernel.Task, skType linux.SockType, protocol Protocol) (*Socke
// Bind the endpoint for good measure so we can connect to it. The
// bound address will never be exposed.
if err := ep.Bind(tcpip.FullAddress{Addr: "dummy"}, nil); err != nil {
if err := ep.Bind(tcpip.FullAddress{Addr: "dummy"}); err != nil {
ep.Close(t)
return nil, err
}
pkg/sentry/socket/netlink/socket_vfs2.go
+1 -1
View File
@@ -57,7 +57,7 @@ func NewVFS2(t *kernel.Task, skType linux.SockType, protocol Protocol) (*SocketV
// Bind the endpoint for good measure so we can connect to it. The
// bound address will never be exposed.
if err := ep.Bind(tcpip.FullAddress{Addr: "dummy"}, nil); err != nil {
if err := ep.Bind(tcpip.FullAddress{Addr: "dummy"}); err != nil {
ep.Close(t)
return nil, err
}
pkg/sentry/socket/unix/transport/connectioned.go
+1 -6
View File
@@ -449,7 +449,7 @@ func (e *connectionedEndpoint) Accept(ctx context.Context, peerAddr *tcpip.FullA
//
// Bind will fail only if the socket is connected, bound or the passed address
// is invalid (the empty string).
func (e *connectionedEndpoint) Bind(addr tcpip.FullAddress, commit func() *syserr.Error) *syserr.Error {
func (e *connectionedEndpoint) Bind(addr tcpip.FullAddress) *syserr.Error {
e.Lock()
defer e.Unlock()
if e.isBound() || e.ListeningLocked() {
@@ -459,11 +459,6 @@ func (e *connectionedEndpoint) Bind(addr tcpip.FullAddress, commit func() *syser
// The empty string is not permitted.
return syserr.ErrBadLocalAddress
}
if commit != nil {
if err := commit(); err != nil {
return err
}
}
// Save the bound address.
e.path = string(addr.Addr)
pkg/sentry/socket/unix/transport/connectionless.go
+1 -6
View File
@@ -164,7 +164,7 @@ func (*connectionlessEndpoint) Accept(context.Context, *tcpip.FullAddress) (Endp
//
// Bind will fail only if the socket is connected, bound or the passed address
// is invalid (the empty string).
func (e *connectionlessEndpoint) Bind(addr tcpip.FullAddress, commit func() *syserr.Error) *syserr.Error {
func (e *connectionlessEndpoint) Bind(addr tcpip.FullAddress) *syserr.Error {
e.Lock()
defer e.Unlock()
if e.isBound() {
@@ -174,11 +174,6 @@ func (e *connectionlessEndpoint) Bind(addr tcpip.FullAddress, commit func() *sys
// The empty string is not permitted.
return syserr.ErrBadLocalAddress
}
if commit != nil {
if err := commit(); err != nil {
return err
}
}
// Save the bound address.
e.path = string(addr.Addr)
pkg/sentry/socket/unix/transport/unix.go
+1 -5
View File
@@ -166,11 +166,7 @@ type Endpoint interface {
// Bind binds the endpoint to a specific local address and port.
// Specifying a NIC is optional.
//
// An optional commit function will be executed atomically with respect
// to binding the endpoint. If this returns an error, the bind will not
// occur and the error will be propagated back to the caller.
Bind(address tcpip.FullAddress, commit func() *syserr.Error) *syserr.Error
Bind(address tcpip.FullAddress) *syserr.Error
// Type return the socket type, typically either SockStream, SockDgram
// or SockSeqpacket.
pkg/sentry/socket/unix/unix.go
+73 -61
View File
@@ -26,6 +26,7 @@ import (
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/marshal"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
@@ -284,69 +285,80 @@ func (s *SocketOperations) Bind(t *kernel.Task, sockaddr []byte) *syserr.Error {
return syserr.ErrInvalidArgument
}
return s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}, func() *syserr.Error {
// Is it abstract?
if p[0] == 0 {
if t.IsNetworkNamespaced() {
return syserr.ErrInvalidEndpointState
}
asn := t.AbstractSockets()
name := p[1:]
if err := asn.Bind(t, name, bep, s); err != nil {
// syserr.ErrPortInUse corresponds to EADDRINUSE.
return syserr.ErrPortInUse
}
s.abstractName = name
s.abstractNamespace = asn
} else {
// The parent and name.
var d *fs.Dirent
var name string
cwd := t.FSContext().WorkingDirectory()
defer cwd.DecRef(t)
// Is there no slash at all?
if !strings.Contains(p, "/") {
d = cwd
name = p
} else {
root := t.FSContext().RootDirectory()
defer root.DecRef(t)
// Find the last path component, we know that something follows
// that final slash, otherwise extractPath() would have failed.
lastSlash := strings.LastIndex(p, "/")
subPath := p[:lastSlash]
if subPath == "" {
// Fix up subpath in case file is in root.
subPath = "/"
}
var err error
remainingTraversals := uint(fs.DefaultTraversalLimit)
d, err = t.MountNamespace().FindInode(t, root, cwd, subPath, &remainingTraversals)
if err != nil {
// No path available.
return syserr.ErrNoSuchFile
}
defer d.DecRef(t)
name = p[lastSlash+1:]
}
// Create the socket.
//
// Note that the file permissions here are not set correctly (see
// gvisor.dev/issue/2324). There is no convenient way to get permissions
// on the socket referred to by s, so we will leave this discrepancy
// unresolved until VFS2 replaces this code.
childDir, err := d.Bind(t, t.FSContext().RootDirectory(), name, bep, fs.FilePermissions{User: fs.PermMask{Read: true}})
if err != nil {
return syserr.ErrPortInUse
}
childDir.DecRef(t)
if p[0] == 0 {
// Abstract socket. See net/unix/af_unix.c:unix_bind_abstract().
if t.IsNetworkNamespaced() {
return syserr.ErrInvalidEndpointState
}
asn := t.AbstractSockets()
name := p[1:]
if err := asn.Bind(t, name, bep, s); err != nil {
// syserr.ErrPortInUse corresponds to EADDRINUSE.
return syserr.ErrPortInUse
}
if err := s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}); err != nil {
asn.Remove(name, s)
return err
}
// The socket has been successfully bound. We can update the following.
s.abstractName = name
s.abstractNamespace = asn
return nil
})
}
// See net/unix/af_unix.c:unix_bind_bsd().
// The parent and name.
var d *fs.Dirent
var name string
cwd := t.FSContext().WorkingDirectory()
defer cwd.DecRef(t)
// Is there no slash at all?
if !strings.Contains(p, "/") {
d = cwd
name = p
} else {
root := t.FSContext().RootDirectory()
defer root.DecRef(t)
// Find the last path component, we know that something follows
// that final slash, otherwise extractPath() would have failed.
lastSlash := strings.LastIndex(p, "/")
subPath := p[:lastSlash]
if subPath == "" {
// Fix up subpath in case file is in root.
subPath = "/"
}
var err error
remainingTraversals := uint(fs.DefaultTraversalLimit)
d, err = t.MountNamespace().FindInode(t, root, cwd, subPath, &remainingTraversals)
if err != nil {
// No path available.
return syserr.ErrNoSuchFile
}
defer d.DecRef(t)
name = p[lastSlash+1:]
}
// Create the socket.
//
// Note that the file permissions here are not set correctly (see
// gvisor.dev/issue/2324). There is no convenient way to get permissions
// on the socket referred to by s, so we will leave this discrepancy
// unresolved until VFS2 replaces this code.
childDir, err := d.Bind(t, t.FSContext().RootDirectory(), name, bep, fs.FilePermissions{User: fs.PermMask{Read: true}})
if err != nil {
return syserr.ErrPortInUse
}
childDir.DecRef(t)
if err := s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}); err != nil {
if removeErr := d.Remove(t, t.FSContext().RootDirectory(), name, false /* dirPath */); removeErr != nil {
log.Warningf("failed to remove socket file created for bind(%q): %v", p, removeErr)
}
return err
}
return nil
}
// extractEndpoint retrieves the transport.BoundEndpoint associated with a Unix
pkg/sentry/socket/unix/unix_vfs2.go
+55 -43
View File
@@ -20,6 +20,7 @@ import (
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/marshal"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/sockfs"
@@ -198,52 +199,63 @@ func (s *SocketVFS2) Bind(t *kernel.Task, sockaddr []byte) *syserr.Error {
return syserr.ErrInvalidArgument
}
return s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}, func() *syserr.Error {
// Is it abstract?
if p[0] == 0 {
if t.IsNetworkNamespaced() {
return syserr.ErrInvalidEndpointState
}
asn := t.AbstractSockets()
name := p[1:]
if err := asn.Bind(t, name, bep, s); err != nil {
// syserr.ErrPortInUse corresponds to EADDRINUSE.
return syserr.ErrPortInUse
}
s.abstractName = name
s.abstractNamespace = asn
} else {
path := fspath.Parse(p)
root := t.FSContext().RootDirectoryVFS2()
defer root.DecRef(t)
start := root
relPath := !path.Absolute
if relPath {
start = t.FSContext().WorkingDirectoryVFS2()
defer start.DecRef(t)
}
pop := vfs.PathOperation{
Root: root,
Start: start,
Path: path,
}
stat, err := s.vfsfd.Stat(t, vfs.StatOptions{Mask: linux.STATX_MODE})
if err != nil {
return syserr.FromError(err)
}
err = t.Kernel().VFS().MknodAt(t, t.Credentials(), &pop, &vfs.MknodOptions{
// File permissions correspond to net/unix/af_unix.c:unix_bind.
Mode: linux.FileMode(linux.S_IFSOCK | uint(stat.Mode)&^t.FSContext().Umask()),
Endpoint: bep,
})
if linuxerr.Equals(linuxerr.EEXIST, err) {
return syserr.ErrAddressInUse
}
return syserr.FromError(err)
if p[0] == 0 {
// Abstract socket. See net/unix/af_unix.c:unix_bind_abstract().
if t.IsNetworkNamespaced() {
return syserr.ErrInvalidEndpointState
}
asn := t.AbstractSockets()
name := p[1:]
if err := asn.Bind(t, name, bep, s); err != nil {
// syserr.ErrPortInUse corresponds to EADDRINUSE.
return syserr.ErrPortInUse
}
if err := s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}); err != nil {
asn.Remove(name, s)
return err
}
// The socket has been successfully bound. We can update the following.
s.abstractName = name
s.abstractNamespace = asn
return nil
}
// See net/unix/af_unix.c:unix_bind_bsd().
path := fspath.Parse(p)
root := t.FSContext().RootDirectoryVFS2()
defer root.DecRef(t)
start := root
relPath := !path.Absolute
if relPath {
start = t.FSContext().WorkingDirectoryVFS2()
defer start.DecRef(t)
}
pop := vfs.PathOperation{
Root: root,
Start: start,
Path: path,
}
stat, err := s.vfsfd.Stat(t, vfs.StatOptions{Mask: linux.STATX_MODE})
if err != nil {
return syserr.FromError(err)
}
err = t.Kernel().VFS().MknodAt(t, t.Credentials(), &pop, &vfs.MknodOptions{
Mode: linux.FileMode(linux.S_IFSOCK | uint(stat.Mode)&^t.FSContext().Umask()),
Endpoint: bep,
})
if linuxerr.Equals(linuxerr.EEXIST, err) {
return syserr.ErrAddressInUse
}
if err != nil {
return syserr.FromError(err)
}
if err := s.ep.Bind(tcpip.FullAddress{Addr: tcpip.Address(p)}); err != nil {
if unlinkErr := t.Kernel().VFS().UnlinkAt(t, t.Credentials(), &pop); unlinkErr != nil {
log.Warningf("failed to unlink socket file created for bind(%q): %v", p, unlinkErr)
}
return err
}
return nil
}
// Ioctl implements vfs.FileDescriptionImpl.