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-rw-r--r--pkg/sentry/fsimpl/verity/filesystem.go45
-rw-r--r--pkg/sentry/fsimpl/verity/verity.go76
-rw-r--r--pkg/sentry/vfs/file_description.go24
3 files changed, 79 insertions, 66 deletions
diff --git a/pkg/sentry/fsimpl/verity/filesystem.go b/pkg/sentry/fsimpl/verity/filesystem.go
index 7779271a9..34e2c9d7c 100644
--- a/pkg/sentry/fsimpl/verity/filesystem.go
+++ b/pkg/sentry/fsimpl/verity/filesystem.go
@@ -156,11 +156,10 @@ afterSymlink:
return child, nil
}
-// verifyChild verifies the root hash of child against the already verified
-// root hash of the parent to ensure the child is expected. verifyChild
-// triggers a sentry panic if unexpected modifications to the file system are
-// detected. In noCrashOnVerificationFailure mode it returns a syserror
-// instead.
+// verifyChild verifies the hash of child against the already verified hash of
+// the parent to ensure the child is expected. verifyChild triggers a sentry
+// panic if unexpected modifications to the file system are detected. In
+// noCrashOnVerificationFailure mode it returns a syserror instead.
// Preconditions: fs.renameMu must be locked. d.dirMu must be locked.
// TODO(b/166474175): Investigate all possible errors returned in this
// function, and make sure we differentiate all errors that indicate unexpected
@@ -179,8 +178,8 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
defer verityMu.RUnlock()
// Read the offset of the child from the extended attributes of the
// corresponding Merkle tree file.
- // This is the offset of the root hash for child in its parent's Merkle
- // tree file.
+ // This is the offset of the hash for child in its parent's Merkle tree
+ // file.
off, err := vfsObj.GetXattrAt(ctx, fs.creds, &vfs.PathOperation{
Root: child.lowerMerkleVD,
Start: child.lowerMerkleVD,
@@ -205,7 +204,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
return nil, alertIntegrityViolation(err, fmt.Sprintf("Failed to convert xattr %s for %s to int: %v", merkleOffsetInParentXattr, childPath, err))
}
- // Open parent Merkle tree file to read and verify child's root hash.
+ // Open parent Merkle tree file to read and verify child's hash.
parentMerkleFD, err := vfsObj.OpenAt(ctx, fs.creds, &vfs.PathOperation{
Root: parent.lowerMerkleVD,
Start: parent.lowerMerkleVD,
@@ -224,7 +223,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// dataSize is the size of raw data for the Merkle tree. For a file,
// dataSize is the size of the whole file. For a directory, dataSize is
- // the size of all its children's root hashes.
+ // the size of all its children's hashes.
dataSize, err := parentMerkleFD.GetXattr(ctx, &vfs.GetXattrOptions{
Name: merkleSizeXattr,
Size: sizeOfStringInt32,
@@ -264,7 +263,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
}
// Since we are verifying against a directory Merkle tree, buf should
- // contain the root hash of the children in the parent Merkle tree when
+ // contain the hash of the children in the parent Merkle tree when
// Verify returns with success.
var buf bytes.Buffer
if _, err := merkletree.Verify(&merkletree.VerifyParams{
@@ -278,21 +277,21 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
GID: parentStat.GID,
ReadOffset: int64(offset),
ReadSize: int64(merkletree.DigestSize()),
- ExpectedRoot: parent.rootHash,
+ Expected: parent.hash,
DataAndTreeInSameFile: true,
}); err != nil && err != io.EOF {
return nil, alertIntegrityViolation(syserror.EIO, fmt.Sprintf("Verification for %s failed: %v", childPath, err))
}
- // Cache child root hash when it's verified the first time.
- if len(child.rootHash) == 0 {
- child.rootHash = buf.Bytes()
+ // Cache child hash when it's verified the first time.
+ if len(child.hash) == 0 {
+ child.hash = buf.Bytes()
}
return child, nil
}
-// verifyStat verifies the stat against the verified root hash. The mode/uid/gid
-// of the file is cached after verified.
+// verifyStat verifies the stat against the verified hash. The mode/uid/gid of
+// the file is cached after verified.
func (fs *filesystem) verifyStat(ctx context.Context, d *dentry, stat linux.Statx) error {
vfsObj := fs.vfsfs.VirtualFilesystem()
@@ -353,7 +352,7 @@ func (fs *filesystem) verifyStat(ctx context.Context, d *dentry, stat linux.Stat
ReadOffset: 0,
// Set read size to 0 so only the metadata is verified.
ReadSize: 0,
- ExpectedRoot: d.rootHash,
+ Expected: d.hash,
DataAndTreeInSameFile: false,
}
if atomic.LoadUint32(&d.mode)&linux.S_IFMT == linux.S_IFDIR {
@@ -375,8 +374,8 @@ func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name s
// If enabling verification on files/directories is not allowed
// during runtime, all cached children are already verified. If
// runtime enable is allowed and the parent directory is
- // enabled, we should verify the child root hash here because
- // it may be cached before enabled.
+ // enabled, we should verify the child hash here because it may
+ // be cached before enabled.
if fs.allowRuntimeEnable {
if isEnabled(parent) {
if _, err := fs.verifyChild(ctx, parent, child); err != nil {
@@ -481,9 +480,9 @@ func (fs *filesystem) lookupAndVerifyLocked(ctx context.Context, parent *dentry,
// file open and ready to use.
// This may cause empty and unused Merkle tree files in
// allowRuntimeEnable mode, if they are never enabled. This
- // does not affect verification, as we rely on cached root hash
- // to decide whether to perform verification, not the existence
- // of the Merkle tree file. Also, those Merkle tree files are
+ // does not affect verification, as we rely on cached hash to
+ // decide whether to perform verification, not the existence of
+ // the Merkle tree file. Also, those Merkle tree files are
// always hidden and cannot be accessed by verity fs users.
if fs.allowRuntimeEnable {
childMerkleFD, err := vfsObj.OpenAt(ctx, fs.creds, &vfs.PathOperation{
@@ -551,7 +550,7 @@ func (fs *filesystem) lookupAndVerifyLocked(ctx context.Context, parent *dentry,
child.uid = stat.UID
child.gid = stat.GID
- // Verify child root hash. This should always be performed unless in
+ // Verify child hash. This should always be performed unless in
// allowRuntimeEnable mode and the parent directory hasn't been enabled
// yet.
if isEnabled(parent) {
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index 3eb972237..4a6708633 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -49,12 +49,12 @@ const Name = "verity"
const merklePrefix = ".merkle.verity."
// merkleoffsetInParentXattr is the extended attribute name specifying the
-// offset of child root hash in its parent's Merkle tree.
+// offset of child hash in its parent's Merkle tree.
const merkleOffsetInParentXattr = "user.merkle.offset"
// merkleSizeXattr is the extended attribute name specifying the size of data
// hashed by the corresponding Merkle tree. For a file, it's the size of the
-// whole file. For a directory, it's the size of all its children's root hashes.
+// whole file. For a directory, it's the size of all its children's hashes.
const merkleSizeXattr = "user.merkle.size"
// sizeOfStringInt32 is the size for a 32 bit integer stored as string in
@@ -147,7 +147,7 @@ func (FilesystemType) Name() string {
// mode, it returns true if the target has been enabled with
// ioctl(FS_IOC_ENABLE_VERITY).
func isEnabled(d *dentry) bool {
- return !d.fs.allowRuntimeEnable || len(d.rootHash) != 0
+ return !d.fs.allowRuntimeEnable || len(d.hash) != 0
}
// alertIntegrityViolation alerts a violation of integrity, which usually means
@@ -256,7 +256,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
d.mode = uint32(stat.Mode)
d.uid = stat.UID
d.gid = stat.GID
- d.rootHash = make([]byte, len(iopts.RootHash))
+ d.hash = make([]byte, len(iopts.RootHash))
if !fs.allowRuntimeEnable {
if err := fs.verifyStat(ctx, d, stat); err != nil {
@@ -264,7 +264,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
}
}
- copy(d.rootHash, iopts.RootHash)
+ copy(d.hash, iopts.RootHash)
d.vfsd.Init(d)
fs.rootDentry = d
@@ -316,8 +316,8 @@ type dentry struct {
// in the underlying file system.
lowerMerkleVD vfs.VirtualDentry
- // rootHash is the rootHash for the current file or directory.
- rootHash []byte
+ // hash is the calculated hash for the current file or directory.
+ hash []byte
}
// newDentry creates a new dentry representing the given verity file. The
@@ -516,11 +516,11 @@ func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions)
}
// generateMerkle generates a Merkle tree file for fd. If fd points to a file
-// /foo/bar, a Merkle tree file /foo/.merkle.verity.bar is generated. The root
-// hash of the generated Merkle tree and the data size is returned.
-// If fd points to a regular file, the data is the content of the file. If fd
-// points to a directory, the data is all root hahes of its children, written
-// to the Merkle tree file.
+// /foo/bar, a Merkle tree file /foo/.merkle.verity.bar is generated. The hash
+// of the generated Merkle tree and the data size is returned. If fd points to
+// a regular file, the data is the content of the file. If fd points to a
+// directory, the data is all hahes of its children, written to the Merkle tree
+// file.
func (fd *fileDescription) generateMerkle(ctx context.Context) ([]byte, uint64, error) {
fdReader := vfs.FileReadWriteSeeker{
FD: fd.lowerFD,
@@ -557,9 +557,9 @@ func (fd *fileDescription) generateMerkle(ctx context.Context) ([]byte, uint64,
params.GID = stat.GID
params.DataAndTreeInSameFile = false
case linux.S_IFDIR:
- // For a directory, generate a Merkle tree based on the root
- // hashes of its children that has already been written to the
- // Merkle tree file.
+ // For a directory, generate a Merkle tree based on the hashes
+ // of its children that has already been written to the Merkle
+ // tree file.
merkleStat, err := fd.merkleReader.Stat(ctx, vfs.StatOptions{})
if err != nil {
return nil, 0, err
@@ -583,12 +583,12 @@ func (fd *fileDescription) generateMerkle(ctx context.Context) ([]byte, uint64,
// enable other types of file.
return nil, 0, syserror.EINVAL
}
- rootHash, err := merkletree.Generate(params)
- return rootHash, uint64(params.Size), err
+ hash, err := merkletree.Generate(params)
+ return hash, uint64(params.Size), err
}
// enableVerity enables verity features on fd by generating a Merkle tree file
-// and stores its root hash in its parent directory's Merkle tree.
+// and stores its hash in its parent directory's Merkle tree.
func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (uintptr, error) {
if !fd.d.fs.allowRuntimeEnable {
return 0, syserror.EPERM
@@ -607,7 +607,7 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (ui
return 0, alertIntegrityViolation(syserror.EIO, "Unexpected verity fd: missing expected underlying fds")
}
- rootHash, dataSize, err := fd.generateMerkle(ctx)
+ hash, dataSize, err := fd.generateMerkle(ctx)
if err != nil {
return 0, err
}
@@ -618,15 +618,15 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (ui
return 0, err
}
- // Write the root hash of fd to the parent directory's Merkle
- // tree file, as it should be part of the parent Merkle tree
- // data. parentMerkleWriter is open with O_APPEND, so it
- // should write directly to the end of the file.
- if _, err = fd.parentMerkleWriter.Write(ctx, usermem.BytesIOSequence(rootHash), vfs.WriteOptions{}); err != nil {
+ // Write the hash of fd to the parent directory's Merkle tree
+ // file, as it should be part of the parent Merkle tree data.
+ // parentMerkleWriter is open with O_APPEND, so it should write
+ // directly to the end of the file.
+ if _, err = fd.parentMerkleWriter.Write(ctx, usermem.BytesIOSequence(hash), vfs.WriteOptions{}); err != nil {
return 0, err
}
- // Record the offset of the root hash of fd in parent directory's
+ // Record the offset of the hash of fd in parent directory's
// Merkle tree file.
if err := fd.merkleWriter.SetXattr(ctx, &vfs.SetXattrOptions{
Name: merkleOffsetInParentXattr,
@@ -643,37 +643,37 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO) (ui
}); err != nil {
return 0, err
}
- fd.d.rootHash = append(fd.d.rootHash, rootHash...)
+ fd.d.hash = append(fd.d.hash, hash...)
return 0, nil
}
-// measureVerity returns the root hash of fd, saved in args[2].
+// measureVerity returns the hash of fd, saved in verityDigest.
func (fd *fileDescription) measureVerity(ctx context.Context, uio usermem.IO, verityDigest usermem.Addr) (uintptr, error) {
t := kernel.TaskFromContext(ctx)
var metadata linux.DigestMetadata
- // If allowRuntimeEnable is true, an empty fd.d.rootHash indicates that
+ // If allowRuntimeEnable is true, an empty fd.d.hash indicates that
// verity is not enabled for the file. If allowRuntimeEnable is false,
// this is an integrity violation because all files should have verity
- // enabled, in which case fd.d.rootHash should be set.
- if len(fd.d.rootHash) == 0 {
+ // enabled, in which case fd.d.hash should be set.
+ if len(fd.d.hash) == 0 {
if fd.d.fs.allowRuntimeEnable {
return 0, syserror.ENODATA
}
- return 0, alertIntegrityViolation(syserror.ENODATA, "Ioctl measureVerity: no root hash found")
+ return 0, alertIntegrityViolation(syserror.ENODATA, "Ioctl measureVerity: no hash found")
}
// The first part of VerityDigest is the metadata.
if _, err := metadata.CopyIn(t, verityDigest); err != nil {
return 0, err
}
- if metadata.DigestSize < uint16(len(fd.d.rootHash)) {
+ if metadata.DigestSize < uint16(len(fd.d.hash)) {
return 0, syserror.EOVERFLOW
}
// Populate the output digest size, since DigestSize is both input and
// output.
- metadata.DigestSize = uint16(len(fd.d.rootHash))
+ metadata.DigestSize = uint16(len(fd.d.hash))
// First copy the metadata.
if _, err := metadata.CopyOut(t, verityDigest); err != nil {
@@ -681,16 +681,16 @@ func (fd *fileDescription) measureVerity(ctx context.Context, uio usermem.IO, ve
}
// Now copy the root hash bytes to the memory after metadata.
- _, err := t.CopyOutBytes(usermem.Addr(uintptr(verityDigest)+linux.SizeOfDigestMetadata), fd.d.rootHash)
+ _, err := t.CopyOutBytes(usermem.Addr(uintptr(verityDigest)+linux.SizeOfDigestMetadata), fd.d.hash)
return 0, err
}
func (fd *fileDescription) verityFlags(ctx context.Context, uio usermem.IO, flags usermem.Addr) (uintptr, error) {
f := int32(0)
- // All enabled files should store a root hash. This flag is not settable
- // via FS_IOC_SETFLAGS.
- if len(fd.d.rootHash) != 0 {
+ // All enabled files should store a hash. This flag is not settable via
+ // FS_IOC_SETFLAGS.
+ if len(fd.d.hash) != 0 {
f |= linux.FS_VERITY_FL
}
@@ -767,7 +767,7 @@ func (fd *fileDescription) PRead(ctx context.Context, dst usermem.IOSequence, of
GID: fd.d.gid,
ReadOffset: offset,
ReadSize: dst.NumBytes(),
- ExpectedRoot: fd.d.rootHash,
+ Expected: fd.d.hash,
DataAndTreeInSameFile: false,
})
if err != nil {
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 1eba0270f..183957ad8 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -827,7 +827,7 @@ func (fd *FileDescription) SetAsyncHandler(newHandler func() FileAsync) FileAsyn
}
// FileReadWriteSeeker is a helper struct to pass a FileDescription as
-// io.Reader/io.Writer/io.ReadSeeker/etc.
+// io.Reader/io.Writer/io.ReadSeeker/io.ReaderAt/io.WriterAt/etc.
type FileReadWriteSeeker struct {
FD *FileDescription
Ctx context.Context
@@ -835,11 +835,18 @@ type FileReadWriteSeeker struct {
WOpts WriteOptions
}
+// ReadAt implements io.ReaderAt.ReadAt.
+func (f *FileReadWriteSeeker) ReadAt(p []byte, off int64) (int, error) {
+ dst := usermem.BytesIOSequence(p)
+ n, err := f.FD.PRead(f.Ctx, dst, off, f.ROpts)
+ return int(n), err
+}
+
// Read implements io.ReadWriteSeeker.Read.
func (f *FileReadWriteSeeker) Read(p []byte) (int, error) {
dst := usermem.BytesIOSequence(p)
- ret, err := f.FD.Read(f.Ctx, dst, f.ROpts)
- return int(ret), err
+ n, err := f.FD.Read(f.Ctx, dst, f.ROpts)
+ return int(n), err
}
// Seek implements io.ReadWriteSeeker.Seek.
@@ -847,9 +854,16 @@ func (f *FileReadWriteSeeker) Seek(offset int64, whence int) (int64, error) {
return f.FD.Seek(f.Ctx, offset, int32(whence))
}
+// WriteAt implements io.WriterAt.WriteAt.
+func (f *FileReadWriteSeeker) WriteAt(p []byte, off int64) (int, error) {
+ dst := usermem.BytesIOSequence(p)
+ n, err := f.FD.PWrite(f.Ctx, dst, off, f.WOpts)
+ return int(n), err
+}
+
// Write implements io.ReadWriteSeeker.Write.
func (f *FileReadWriteSeeker) Write(p []byte) (int, error) {
buf := usermem.BytesIOSequence(p)
- ret, err := f.FD.Write(f.Ctx, buf, f.WOpts)
- return int(ret), err
+ n, err := f.FD.Write(f.Ctx, buf, f.WOpts)
+ return int(n), err
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 22:29:33 +0000