Merge release-20200804.0-35-gf20e63e31 (automated)

3 files changed, 36 insertions, 16 deletions

diff --git a/pkg/abi/linux/linux_abi_autogen_unsafe.go b/pkg/abi/linux/linux_abi_autogen_unsafe.go
index d4736983b..74feacefb 100644
--- a/pkg/abi/linux/linux_abi_autogen_unsafe.go
+++ b/pkg/abi/linux/linux_abi_autogen_unsafe.go
@@ -150,7 +150,7 @@ func (s *Statx) Packed() bool {
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
 func (s *Statx) MarshalUnsafe(dst []byte) {
-    if s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() && s.Btime.Packed() {
+    if s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() {
         safecopy.CopyIn(dst, unsafe.Pointer(s))
     } else {
         // Type Statx doesn't have a packed layout in memory, fallback to MarshalBytes.
@@ -227,7 +227,7 @@ func (s *Statx) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
 
 // WriteTo implements io.WriterTo.WriteTo.
 func (s *Statx) WriteTo(w io.Writer) (int64, error) {
-    if !s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() {
+    if !s.Mtime.Packed() && s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() {
         // Type Statx doesn't have a packed layout in memory, fall back to MarshalBytes.
         buf := make([]byte, s.SizeBytes())
         s.MarshalBytes(buf)
@@ -635,7 +635,7 @@ func (f *FUSEHeaderIn) MarshalUnsafe(dst []byte) {
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
 func (f *FUSEHeaderIn) UnmarshalUnsafe(src []byte) {
-    if f.Unique.Packed() && f.Opcode.Packed() {
+    if f.Opcode.Packed() && f.Unique.Packed() {
         safecopy.CopyOut(unsafe.Pointer(f), src)
     } else {
         // Type FUSEHeaderIn doesn't have a packed layout in memory, fallback to UnmarshalBytes.
@@ -676,7 +676,7 @@ func (f *FUSEHeaderIn) CopyOut(task marshal.Task, addr usermem.Addr) (int, error
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
 func (f *FUSEHeaderIn) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
-    if !f.Opcode.Packed() && f.Unique.Packed() {
+    if !f.Unique.Packed() && f.Opcode.Packed() {
         // Type FUSEHeaderIn doesn't have a packed layout in memory, fall back to UnmarshalBytes.
         buf := task.CopyScratchBuffer(f.SizeBytes()) // escapes: okay.
         length, err := task.CopyInBytes(addr, buf) // escapes: okay.
@@ -1686,7 +1686,7 @@ func (i *IPTEntry) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) {
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
 func (i *IPTEntry) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
-    if !i.Counters.Packed() && i.IP.Packed() {
+    if !i.IP.Packed() && i.Counters.Packed() {
         // Type IPTEntry doesn't have a packed layout in memory, fall back to UnmarshalBytes.
         buf := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay.
         length, err := task.CopyInBytes(addr, buf) // escapes: okay.
@@ -1712,7 +1712,7 @@ func (i *IPTEntry) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
 
 // WriteTo implements io.WriterTo.WriteTo.
 func (i *IPTEntry) WriteTo(w io.Writer) (int64, error) {
-    if !i.IP.Packed() && i.Counters.Packed() {
+    if !i.Counters.Packed() && i.IP.Packed() {
         // Type IPTEntry doesn't have a packed layout in memory, fall back to MarshalBytes.
         buf := make([]byte, i.SizeBytes())
         i.MarshalBytes(buf)
@@ -1818,12 +1818,12 @@ func (i *IPTIP) UnmarshalBytes(src []byte) {
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
 func (i *IPTIP) Packed() bool {
-    return i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed()
+    return i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed()
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
 func (i *IPTIP) MarshalUnsafe(dst []byte) {
-    if i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() {
+    if i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() {
         safecopy.CopyIn(dst, unsafe.Pointer(i))
     } else {
         // Type IPTIP doesn't have a packed layout in memory, fallback to MarshalBytes.
@@ -1833,7 +1833,7 @@ func (i *IPTIP) MarshalUnsafe(dst []byte) {
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
 func (i *IPTIP) UnmarshalUnsafe(src []byte) {
-    if i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() {
+    if i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() {
         safecopy.CopyOut(unsafe.Pointer(i), src)
     } else {
         // Type IPTIP doesn't have a packed layout in memory, fallback to UnmarshalBytes.
@@ -1844,7 +1844,7 @@ func (i *IPTIP) UnmarshalUnsafe(src []byte) {
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
 func (i *IPTIP) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, error) {
-    if !i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() {
+    if !i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() {
         // Type IPTIP doesn't have a packed layout in memory, fall back to MarshalBytes.
         buf := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay.
         i.MarshalBytes(buf) // escapes: fallback.
@@ -1874,7 +1874,7 @@ func (i *IPTIP) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) {
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
 func (i *IPTIP) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
-    if !i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() {
+    if !i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() {
         // Type IPTIP doesn't have a packed layout in memory, fall back to UnmarshalBytes.
         buf := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay.
         length, err := task.CopyInBytes(addr, buf) // escapes: okay.
@@ -1900,7 +1900,7 @@ func (i *IPTIP) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
 
 // WriteTo implements io.WriterTo.WriteTo.
 func (i *IPTIP) WriteTo(w io.Writer) (int64, error) {
-    if !i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() {
+    if !i.DstMask.Packed() && i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() {
         // Type IPTIP doesn't have a packed layout in memory, fall back to MarshalBytes.
         buf := make([]byte, i.SizeBytes())
         i.MarshalBytes(buf)
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index e6af37d0d..582b744bb 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -15,6 +15,7 @@
 package gofer
 
 import (
+	"math"
 	"sync"
 	"sync/atomic"
 
@@ -724,8 +725,29 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
 		if rp.Mount() != vd.Mount() {
 			return syserror.EXDEV
 		}
-		// 9P2000.L supports hard links, but we don't.
-		return syserror.EPERM
+		d := vd.Dentry().Impl().(*dentry)
+		if d.isDir() {
+			return syserror.EPERM
+		}
+		gid := auth.KGID(atomic.LoadUint32(&d.gid))
+		uid := auth.KUID(atomic.LoadUint32(&d.uid))
+		mode := linux.FileMode(atomic.LoadUint32(&d.mode))
+		if err := vfs.MayLink(rp.Credentials(), mode, uid, gid); err != nil {
+			return err
+		}
+		if d.nlink == 0 {
+			return syserror.ENOENT
+		}
+		if d.nlink == math.MaxUint32 {
+			return syserror.EMLINK
+		}
+		if err := parent.file.link(ctx, d.file, childName); err != nil {
+			return err
+		}
+
+		// Success!
+		atomic.AddUint32(&d.nlink, 1)
+		return nil
 	}, nil)
 }
 
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 2e5575d8d..6ae796c6d 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -558,8 +558,6 @@ type dentry struct {
 	// filesystem.renameMu.
 	name string
 
-	// We don't support hard links, so each dentry maps 1:1 to an inode.
-
 	// file is the unopened p9.File that backs this dentry. file is immutable.
 	//
 	// If file.isNil(), this dentry represents a synthetic file, i.e. a file