summaryrefslogtreecommitdiffhomepage
path: root/pkg/sentry/fsimpl/verity/verity.go
diff options
context:
space:
mode:
Diffstat (limited to 'pkg/sentry/fsimpl/verity/verity.go')
-rw-r--r--pkg/sentry/fsimpl/verity/verity.go155
1 files changed, 139 insertions, 16 deletions
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index faa862c55..87dabe038 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -22,6 +22,7 @@
package verity
import (
+ "encoding/json"
"fmt"
"math"
"strconv"
@@ -60,6 +61,15 @@ const (
// file size. For a directory, this is the size of all its children's hashes.
merkleSizeXattr = "user.merkle.size"
+ // childrenOffsetXattr is the extended attribute name specifying the
+ // names of the offset of the serialized children names in the Merkle
+ // tree file.
+ childrenOffsetXattr = "user.merkle.childrenOffset"
+
+ // childrenSizeXattr is the extended attribute name specifying the size
+ // of the serialized children names.
+ childrenSizeXattr = "user.merkle.childrenSize"
+
// sizeOfStringInt32 is the size for a 32 bit integer stored as string in
// extended attributes. The maximum value of a 32 bit integer has 10 digits.
sizeOfStringInt32 = 10
@@ -299,9 +309,70 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
d.uid = stat.UID
d.gid = stat.GID
d.hash = make([]byte, len(iopts.RootHash))
+ d.childrenNames = make(map[string]struct{})
if !fs.allowRuntimeEnable {
- if err := fs.verifyStat(ctx, d, stat); err != nil {
+ // Get children names from the underlying file system.
+ offString, err := vfsObj.GetXattrAt(ctx, creds, &vfs.PathOperation{
+ Root: lowerMerkleVD,
+ Start: lowerMerkleVD,
+ }, &vfs.GetXattrOptions{
+ Name: childrenOffsetXattr,
+ Size: sizeOfStringInt32,
+ })
+ if err == syserror.ENOENT || err == syserror.ENODATA {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to get xattr %s: %v", childrenOffsetXattr, err))
+ }
+ if err != nil {
+ return nil, nil, err
+ }
+
+ off, err := strconv.Atoi(offString)
+ if err != nil {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to convert xattr %s to int: %v", childrenOffsetXattr, err))
+ }
+
+ sizeString, err := vfsObj.GetXattrAt(ctx, creds, &vfs.PathOperation{
+ Root: lowerMerkleVD,
+ Start: lowerMerkleVD,
+ }, &vfs.GetXattrOptions{
+ Name: childrenSizeXattr,
+ Size: sizeOfStringInt32,
+ })
+ if err == syserror.ENOENT || err == syserror.ENODATA {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to get xattr %s: %v", childrenSizeXattr, err))
+ }
+ if err != nil {
+ return nil, nil, err
+ }
+ size, err := strconv.Atoi(sizeString)
+ if err != nil {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to convert xattr %s to int: %v", childrenSizeXattr, err))
+ }
+
+ lowerMerkleFD, err := vfsObj.OpenAt(ctx, fs.creds, &vfs.PathOperation{
+ Root: lowerMerkleVD,
+ Start: lowerMerkleVD,
+ }, &vfs.OpenOptions{
+ Flags: linux.O_RDONLY,
+ })
+ if err == syserror.ENOENT {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to open root Merkle file: %v", err))
+ }
+ if err != nil {
+ return nil, nil, err
+ }
+
+ childrenNames := make([]byte, size)
+ if _, err := lowerMerkleFD.PRead(ctx, usermem.BytesIOSequence(childrenNames), int64(off), vfs.ReadOptions{}); err != nil {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to read root children map: %v", err))
+ }
+
+ if err := json.Unmarshal(childrenNames, &d.childrenNames); err != nil {
+ return nil, nil, alertIntegrityViolation(fmt.Sprintf("Failed to deserialize childrenNames: %v", err))
+ }
+
+ if err := fs.verifyStatAndChildren(ctx, d, stat); err != nil {
return nil, nil, err
}
}
@@ -352,6 +423,11 @@ type dentry struct {
dirMu sync.Mutex `state:"nosave"`
children map[string]*dentry
+ // childrenNames stores the name of all children of the dentry. This is
+ // used by verity to check whether a child is expected. This is only
+ // populated by enableVerity.
+ childrenNames map[string]struct{}
+
// lowerVD is the VirtualDentry in the underlying file system.
lowerVD vfs.VirtualDentry
@@ -603,7 +679,7 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
return linux.Statx{}, err
}
if fd.d.verityEnabled() {
- if err := fd.d.fs.verifyStat(ctx, fd.d, stat); err != nil {
+ if err := fd.d.fs.verifyStatAndChildren(ctx, fd.d, stat); err != nil {
return linux.Statx{}, err
}
}
@@ -664,6 +740,7 @@ func (fd *fileDescription) generateMerkle(ctx context.Context) ([]byte, uint64,
params := &merkletree.GenerateParams{
TreeReader: &merkleReader,
TreeWriter: &merkleWriter,
+ Children: fd.d.childrenNames,
//TODO(b/156980949): Support passing other hash algorithms.
HashAlgorithms: fd.d.fs.alg.toLinuxHashAlg(),
}
@@ -716,9 +793,45 @@ func (fd *fileDescription) generateMerkle(ctx context.Context) ([]byte, uint64,
return hash, uint64(params.Size), err
}
+// recordChildren writes the names of fd's children into the corresponding
+// Merkle tree file, and saves the offset/size of the map into xattrs.
+//
+// Preconditions: fd.d.isDir() == true
+func (fd *fileDescription) recordChildren(ctx context.Context) error {
+ // Record the children names in the Merkle tree file.
+ childrenNames, err := json.Marshal(fd.d.childrenNames)
+ if err != nil {
+ return err
+ }
+
+ stat, err := fd.merkleWriter.Stat(ctx, vfs.StatOptions{})
+ if err != nil {
+ return err
+ }
+
+ if err := fd.merkleWriter.SetXattr(ctx, &vfs.SetXattrOptions{
+ Name: childrenOffsetXattr,
+ Value: strconv.Itoa(int(stat.Size)),
+ }); err != nil {
+ return err
+ }
+ if err := fd.merkleWriter.SetXattr(ctx, &vfs.SetXattrOptions{
+ Name: childrenSizeXattr,
+ Value: strconv.Itoa(len(childrenNames)),
+ }); err != nil {
+ return err
+ }
+
+ if _, err = fd.merkleWriter.Write(ctx, usermem.BytesIOSequence(childrenNames), vfs.WriteOptions{}); err != nil {
+ return err
+ }
+
+ return nil
+}
+
// enableVerity enables verity features on fd by generating a Merkle tree file
// and stores its hash in its parent directory's Merkle tree.
-func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (uintptr, error) {
+func (fd *fileDescription) enableVerity(ctx context.Context) (uintptr, error) {
if !fd.d.fs.allowRuntimeEnable {
return 0, syserror.EPERM
}
@@ -761,6 +874,9 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (ui
}); err != nil {
return 0, err
}
+
+ // Add the current child's name to parent's childrenNames.
+ fd.d.parent.childrenNames[fd.d.name] = struct{}{}
}
// Record the size of the data being hashed for fd.
@@ -770,12 +886,18 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (ui
}); err != nil {
return 0, err
}
+
+ if fd.d.isDir() {
+ if err := fd.recordChildren(ctx); err != nil {
+ return 0, err
+ }
+ }
fd.d.hash = append(fd.d.hash, hash...)
return 0, nil
}
// measureVerity returns the hash of fd, saved in verityDigest.
-func (fd *fileDescription) measureVerity(ctx context.Context, uio usermem.IO, verityDigest usermem.Addr) (uintptr, error) {
+func (fd *fileDescription) measureVerity(ctx context.Context, verityDigest usermem.Addr) (uintptr, error) {
t := kernel.TaskFromContext(ctx)
if t == nil {
return 0, syserror.EINVAL
@@ -815,7 +937,7 @@ func (fd *fileDescription) measureVerity(ctx context.Context, uio usermem.IO, ve
return 0, err
}
-func (fd *fileDescription) verityFlags(ctx context.Context, uio usermem.IO, flags usermem.Addr) (uintptr, error) {
+func (fd *fileDescription) verityFlags(ctx context.Context, flags usermem.Addr) (uintptr, error) {
f := int32(0)
// All enabled files should store a hash. This flag is not settable via
@@ -836,11 +958,11 @@ func (fd *fileDescription) verityFlags(ctx context.Context, uio usermem.IO, flag
func (fd *fileDescription) Ioctl(ctx context.Context, uio usermem.IO, args arch.SyscallArguments) (uintptr, error) {
switch cmd := args[1].Uint(); cmd {
case linux.FS_IOC_ENABLE_VERITY:
- return fd.enableVerity(ctx, uio)
+ return fd.enableVerity(ctx)
case linux.FS_IOC_MEASURE_VERITY:
- return fd.measureVerity(ctx, uio, args[2].Pointer())
+ return fd.measureVerity(ctx, args[2].Pointer())
case linux.FS_IOC_GETFLAGS:
- return fd.verityFlags(ctx, uio, args[2].Pointer())
+ return fd.verityFlags(ctx, args[2].Pointer())
default:
// TODO(b/169682228): Investigate which ioctl commands should
// be allowed.
@@ -902,14 +1024,15 @@ func (fd *fileDescription) PRead(ctx context.Context, dst usermem.IOSequence, of
}
n, err := merkletree.Verify(&merkletree.VerifyParams{
- Out: dst.Writer(ctx),
- File: &dataReader,
- Tree: &merkleReader,
- Size: int64(size),
- Name: fd.d.name,
- Mode: fd.d.mode,
- UID: fd.d.uid,
- GID: fd.d.gid,
+ Out: dst.Writer(ctx),
+ File: &dataReader,
+ Tree: &merkleReader,
+ Size: int64(size),
+ Name: fd.d.name,
+ Mode: fd.d.mode,
+ UID: fd.d.uid,
+ GID: fd.d.gid,
+ Children: fd.d.childrenNames,
//TODO(b/156980949): Support passing other hash algorithms.
HashAlgorithms: fd.d.fs.alg.toLinuxHashAlg(),
ReadOffset: offset,
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 13:52:19 +0000