Merge release-20200622.1-210-gd9a3f5d0c (automated)

12 files changed, 54 insertions, 21 deletions

diff --git a/pkg/abi/linux/linux_abi_autogen_unsafe.go b/pkg/abi/linux/linux_abi_autogen_unsafe.go
index cc27800d2..ddd4c644b 100644
--- a/pkg/abi/linux/linux_abi_autogen_unsafe.go
+++ b/pkg/abi/linux/linux_abi_autogen_unsafe.go
@@ -159,7 +159,7 @@ func (s *Statx) UnmarshalUnsafe(src []byte) {
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
 func (s *Statx) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, error) {
-    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() {
         // Type Statx doesn't have a packed layout in memory, fall back to MarshalBytes.
         buf := task.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
         s.MarshalBytes(buf) // escapes: fallback.
@@ -189,7 +189,7 @@ func (s *Statx) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) {
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
 func (s *Statx) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) {
-    if !s.Atime.Packed() && s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() {
+    if !s.Btime.Packed() && s.Ctime.Packed() && s.Mtime.Packed() && s.Atime.Packed() {
         // Type Statx doesn't have a packed layout in memory, fall back to UnmarshalBytes.
         buf := task.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
         length, err := task.CopyInBytes(addr, buf) // escapes: okay.
@@ -632,7 +632,7 @@ func (i *IPTEntry) UnmarshalUnsafe(src []byte) {
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
 func (i *IPTEntry) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, 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 := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay.
         i.MarshalBytes(buf) // escapes: fallback.
@@ -799,7 +799,7 @@ func (i *IPTIP) Packed() bool {
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
 func (i *IPTIP) MarshalUnsafe(dst []byte) {
-    if i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.Packed() {
+    if i.Src.Packed() && i.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() {
         safecopy.CopyIn(dst, unsafe.Pointer(i))
     } else {
         i.MarshalBytes(dst)
@@ -808,7 +808,7 @@ 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 {
         i.UnmarshalBytes(src)
@@ -818,7 +818,7 @@ 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.Dst.Packed() && i.SrcMask.Packed() && i.DstMask.Packed() && i.Src.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 := task.CopyScratchBuffer(i.SizeBytes()) // escapes: okay.
         i.MarshalBytes(buf) // escapes: fallback.
@@ -874,7 +874,7 @@ 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.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 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 491495b16..00e3c99cd 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -1334,7 +1334,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
 		fs.renameMuRUnlockAndCheckCaching(&ds)
 		return err
 	}
-	if err := d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()); err != nil {
+	if err := d.setStat(ctx, rp.Credentials(), &opts, rp.Mount()); err != nil {
 		fs.renameMuRUnlockAndCheckCaching(&ds)
 		return err
 	}
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index ba7f650b3..e20de84b5 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -888,7 +888,8 @@ func (d *dentry) statTo(stat *linux.Statx) {
 	stat.DevMinor = d.fs.devMinor
 }
 
-func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mnt *vfs.Mount) error {
+func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions, mnt *vfs.Mount) error {
+	stat := &opts.Stat
 	if stat.Mask == 0 {
 		return nil
 	}
@@ -896,7 +897,7 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
 		return syserror.EPERM
 	}
 	mode := linux.FileMode(atomic.LoadUint32(&d.mode))
-	if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+	if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
 		return err
 	}
 	if err := mnt.CheckBeginWrite(); err != nil {
@@ -937,6 +938,17 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
 	}
 	if !d.isSynthetic() {
 		if stat.Mask != 0 {
+			if stat.Mask&linux.STATX_SIZE != 0 {
+				// Check whether to allow a truncate request to be made.
+				switch d.mode & linux.S_IFMT {
+				case linux.S_IFREG:
+					// Allow.
+				case linux.S_IFDIR:
+					return syserror.EISDIR
+				default:
+					return syserror.EINVAL
+				}
+			}
 			if err := d.file.setAttr(ctx, p9.SetAttrMask{
 				Permissions:        stat.Mask&linux.STATX_MODE != 0,
 				UID:                stat.Mask&linux.STATX_UID != 0,
@@ -1498,7 +1510,7 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
 
 // SetStat implements vfs.FileDescriptionImpl.SetStat.
 func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
-	if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()); err != nil {
+	if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts, fd.vfsfd.Mount()); err != nil {
 		return err
 	}
 	if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go
index 1a88cb657..c894f2ca0 100644
--- a/pkg/sentry/fsimpl/host/host.go
+++ b/pkg/sentry/fsimpl/host/host.go
@@ -373,7 +373,7 @@ func (i *inode) fstat(fs *filesystem) (linux.Statx, error) {
 
 // SetStat implements kernfs.Inode.
 func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
-	s := opts.Stat
+	s := &opts.Stat
 
 	m := s.Mask
 	if m == 0 {
@@ -386,7 +386,7 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
 	if err := syscall.Fstat(i.hostFD, &hostStat); err != nil {
 		return err
 	}
-	if err := vfs.CheckSetStat(ctx, creds, &s, linux.FileMode(hostStat.Mode&linux.PermissionsMask), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil {
+	if err := vfs.CheckSetStat(ctx, creds, &opts, linux.FileMode(hostStat.Mode), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil {
 		return err
 	}
 
@@ -396,6 +396,9 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
 		}
 	}
 	if m&linux.STATX_SIZE != 0 {
+		if hostStat.Mode&linux.S_IFMT != linux.S_IFREG {
+			return syserror.EINVAL
+		}
 		if err := syscall.Ftruncate(i.hostFD, int64(s.Size)); err != nil {
 			return err
 		}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 2ab3f1761..579e627f0 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -267,7 +267,7 @@ func (a *InodeAttrs) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *aut
 	if opts.Stat.Mask&^(linux.STATX_MODE|linux.STATX_UID|linux.STATX_GID) != 0 {
 		return syserror.EPERM
 	}
-	if err := vfs.CheckSetStat(ctx, creds, &opts.Stat, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil {
+	if err := vfs.CheckSetStat(ctx, creds, &opts, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil {
 		return err
 	}
 
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index ff82e1f20..6b705e955 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -1104,7 +1104,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
 	}
 
 	mode := linux.FileMode(atomic.LoadUint32(&d.mode))
-	if err := vfs.CheckSetStat(ctx, rp.Credentials(), &opts.Stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+	if err := vfs.CheckSetStat(ctx, rp.Credentials(), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
 		return err
 	}
 	mnt := rp.Mount()
diff --git a/pkg/sentry/fsimpl/overlay/non_directory.go b/pkg/sentry/fsimpl/overlay/non_directory.go
index 6c8445ea1..c0749e711 100644
--- a/pkg/sentry/fsimpl/overlay/non_directory.go
+++ b/pkg/sentry/fsimpl/overlay/non_directory.go
@@ -151,7 +151,7 @@ func (fd *nonDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux
 func (fd *nonDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
 	d := fd.dentry()
 	mode := linux.FileMode(atomic.LoadUint32(&d.mode))
-	if err := vfs.CheckSetStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+	if err := vfs.CheckSetStat(ctx, auth.CredentialsFromContext(ctx), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
 		return err
 	}
 	mnt := fd.vfsfd.Mount()
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index a0f20c2d4..ef210a69b 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -649,7 +649,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
 		fs.mu.RUnlock()
 		return err
 	}
-	if err := d.inode.setStat(ctx, rp.Credentials(), &opts.Stat); err != nil {
+	if err := d.inode.setStat(ctx, rp.Credentials(), &opts); err != nil {
 		fs.mu.RUnlock()
 		return err
 	}
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index d7f4f0779..2545d88e9 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -452,7 +452,8 @@ func (i *inode) statTo(stat *linux.Statx) {
 	}
 }
 
-func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx) error {
+func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions) error {
+	stat := &opts.Stat
 	if stat.Mask == 0 {
 		return nil
 	}
@@ -460,7 +461,7 @@ func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linu
 		return syserror.EPERM
 	}
 	mode := linux.FileMode(atomic.LoadUint32(&i.mode))
-	if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil {
+	if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil {
 		return err
 	}
 	i.mu.Lock()
@@ -695,7 +696,7 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
 func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
 	creds := auth.CredentialsFromContext(ctx)
 	d := fd.dentry()
-	if err := d.inode.setStat(ctx, creds, &opts.Stat); err != nil {
+	if err := d.inode.setStat(ctx, creds, &opts); err != nil {
 		return err
 	}
 
diff --git a/pkg/sentry/syscalls/linux/vfs2/setstat.go b/pkg/sentry/syscalls/linux/vfs2/setstat.go
index 09ecfed26..6daedd173 100644
--- a/pkg/sentry/syscalls/linux/vfs2/setstat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/setstat.go
@@ -178,6 +178,7 @@ func Truncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 			Mask: linux.STATX_SIZE,
 			Size: uint64(length),
 		},
+		NeedWritePerm: true,
 	})
 	return 0, nil, handleSetSizeError(t, err)
 }
@@ -197,6 +198,10 @@ func Ftruncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	}
 	defer file.DecRef()
 
+	if !file.IsWritable() {
+		return 0, nil, syserror.EINVAL
+	}
+
 	err := file.SetStat(t, vfs.SetStatOptions{
 		Stat: linux.Statx{
 			Mask: linux.STATX_SIZE,
diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go
index d37208a1f..dfc8573fd 100644
--- a/pkg/sentry/vfs/options.go
+++ b/pkg/sentry/vfs/options.go
@@ -164,6 +164,12 @@ type SetStatOptions struct {
 	// == UTIME_OMIT (VFS users must unset the corresponding bit in Stat.Mask
 	// instead).
 	Stat linux.Statx
+
+	// NeedWritePerm indicates that write permission on the file is needed for
+	// this operation. This is needed for truncate(2) (note that ftruncate(2)
+	// does not require the same check--instead, it checks that the fd is
+	// writable).
+	NeedWritePerm bool
 }
 
 // BoundEndpointOptions contains options to VirtualFilesystem.BoundEndpointAt()
diff --git a/pkg/sentry/vfs/permissions.go b/pkg/sentry/vfs/permissions.go
index 9cb050597..33389c1df 100644
--- a/pkg/sentry/vfs/permissions.go
+++ b/pkg/sentry/vfs/permissions.go
@@ -183,7 +183,8 @@ func MayWriteFileWithOpenFlags(flags uint32) bool {
 // CheckSetStat checks that creds has permission to change the metadata of a
 // file with the given permissions, UID, and GID as specified by stat, subject
 // to the rules of Linux's fs/attr.c:setattr_prepare().
-func CheckSetStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mode linux.FileMode, kuid auth.KUID, kgid auth.KGID) error {
+func CheckSetStat(ctx context.Context, creds *auth.Credentials, opts *SetStatOptions, mode linux.FileMode, kuid auth.KUID, kgid auth.KGID) error {
+	stat := &opts.Stat
 	if stat.Mask&linux.STATX_SIZE != 0 {
 		limit, err := CheckLimit(ctx, 0, int64(stat.Size))
 		if err != nil {
@@ -215,6 +216,11 @@ func CheckSetStat(ctx context.Context, creds *auth.Credentials, stat *linux.Stat
 			return syserror.EPERM
 		}
 	}
+	if opts.NeedWritePerm && !creds.HasCapability(linux.CAP_DAC_OVERRIDE) {
+		if err := GenericCheckPermissions(creds, MayWrite, mode, kuid, kgid); err != nil {
+			return err
+		}
+	}
 	if stat.Mask&(linux.STATX_ATIME|linux.STATX_MTIME|linux.STATX_CTIME) != 0 {
 		if !CanActAsOwner(creds, kuid) {
 			if (stat.Mask&linux.STATX_ATIME != 0 && stat.Atime.Nsec != linux.UTIME_NOW) ||