summaryrefslogtreecommitdiffhomepage
path: root/pkg/sentry/fsimpl
diff options
context:
space:
mode:
Diffstat (limited to 'pkg/sentry/fsimpl')
-rw-r--r--pkg/sentry/fsimpl/verity/filesystem.go222
-rw-r--r--pkg/sentry/fsimpl/verity/verity.go77
2 files changed, 252 insertions, 47 deletions
diff --git a/pkg/sentry/fsimpl/verity/filesystem.go b/pkg/sentry/fsimpl/verity/filesystem.go
index 2cf0a38c9..f86a6a0b2 100644
--- a/pkg/sentry/fsimpl/verity/filesystem.go
+++ b/pkg/sentry/fsimpl/verity/filesystem.go
@@ -19,6 +19,7 @@ import (
"fmt"
"io"
"strconv"
+ "strings"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
@@ -192,10 +193,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// contains the expected xattrs. If the file or the xattr does not
// exist, it indicates unexpected modifications to the file system.
if err == syserror.ENOENT || err == syserror.ENODATA {
- if noCrashOnVerificationFailure {
- return nil, err
- }
- panic(fmt.Sprintf("Failed to get xattr %s for %s: %v", merkleOffsetInParentXattr, childPath, err))
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Failed to get xattr %s for %s: %v", merkleOffsetInParentXattr, childPath, err))
}
if err != nil {
return nil, err
@@ -204,10 +202,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// unexpected modifications to the file system.
offset, err := strconv.Atoi(off)
if err != nil {
- if noCrashOnVerificationFailure {
- return nil, syserror.EINVAL
- }
- panic(fmt.Sprintf("Failed to convert xattr %s for %s to int: %v", merkleOffsetInParentXattr, childPath, err))
+ 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.
@@ -221,10 +216,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// The parent Merkle tree file should have been created. If it's
// missing, it indicates an unexpected modification to the file system.
if err == syserror.ENOENT {
- if noCrashOnVerificationFailure {
- return nil, err
- }
- panic(fmt.Sprintf("Failed to open parent Merkle file for %s: %v", childPath, err))
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Failed to open parent Merkle file for %s: %v", childPath, err))
}
if err != nil {
return nil, err
@@ -242,10 +234,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// contains the expected xattrs. If the file or the xattr does not
// exist, it indicates unexpected modifications to the file system.
if err == syserror.ENOENT || err == syserror.ENODATA {
- if noCrashOnVerificationFailure {
- return nil, err
- }
- panic(fmt.Sprintf("Failed to get xattr %s for %s: %v", merkleSizeXattr, childPath, err))
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Failed to get xattr %s for %s: %v", merkleSizeXattr, childPath, err))
}
if err != nil {
return nil, err
@@ -255,10 +244,7 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// unexpected modifications to the file system.
parentSize, err := strconv.Atoi(dataSize)
if err != nil {
- if noCrashOnVerificationFailure {
- return nil, syserror.EINVAL
- }
- panic(fmt.Sprintf("Failed to convert xattr %s for %s to int: %v", merkleSizeXattr, childPath, err))
+ return nil, alertIntegrityViolation(syserror.EINVAL, fmt.Sprintf("Failed to convert xattr %s for %s to int: %v", merkleSizeXattr, childPath, err))
}
fdReader := vfs.FileReadWriteSeeker{
@@ -270,11 +256,8 @@ func (fs *filesystem) verifyChild(ctx context.Context, parent *dentry, child *de
// contain the root hash of the children in the parent Merkle tree when
// Verify returns with success.
var buf bytes.Buffer
- if err := merkletree.Verify(&buf, &fdReader, &fdReader, int64(parentSize), int64(offset), int64(merkletree.DigestSize()), parent.rootHash, true /* dataAndTreeInSameFile */); err != nil && err != io.EOF {
- if noCrashOnVerificationFailure {
- return nil, syserror.EIO
- }
- panic(fmt.Sprintf("Verification for %s failed: %v", childPath, err))
+ if _, err := merkletree.Verify(&buf, &fdReader, &fdReader, int64(parentSize), int64(offset), int64(merkletree.DigestSize()), parent.rootHash, true /* dataAndTreeInSameFile */); 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.
@@ -370,10 +353,7 @@ func (fs *filesystem) lookupAndVerifyLocked(ctx context.Context, parent *dentry,
// corresponding Merkle tree is found. This indicates an
// unexpected modification to the file system that
// removed/renamed the child.
- if noCrashOnVerificationFailure {
- return nil, childErr
- }
- panic(fmt.Sprintf("Target file %s is expected but missing", parentPath+"/"+name))
+ return nil, alertIntegrityViolation(childErr, fmt.Sprintf("Target file %s is expected but missing", parentPath+"/"+name))
} else if childErr == nil && childMerkleErr == syserror.ENOENT {
// If in allowRuntimeEnable mode, and the Merkle tree file is
// not created yet, we create an empty Merkle tree file, so that
@@ -409,10 +389,7 @@ func (fs *filesystem) lookupAndVerifyLocked(ctx context.Context, parent *dentry,
// If runtime enable is not allowed. This indicates an
// unexpected modification to the file system that
// removed/renamed the Merkle tree file.
- if noCrashOnVerificationFailure {
- return nil, childMerkleErr
- }
- panic(fmt.Sprintf("Expected Merkle file for target %s but none found", parentPath+"/"+name))
+ return nil, alertIntegrityViolation(childMerkleErr, fmt.Sprintf("Expected Merkle file for target %s but none found", parentPath+"/"+name))
}
} else if childErr == syserror.ENOENT && childMerkleErr == syserror.ENOENT {
// Both the child and the corresponding Merkle tree are missing.
@@ -421,7 +398,7 @@ func (fs *filesystem) lookupAndVerifyLocked(ctx context.Context, parent *dentry,
// TODO(b/167752508): Investigate possible ways to differentiate
// cases that both files are deleted from cases that they never
// exist in the file system.
- panic(fmt.Sprintf("Failed to find file %s", parentPath+"/"+name))
+ return nil, alertIntegrityViolation(childErr, fmt.Sprintf("Failed to find file %s", parentPath+"/"+name))
}
mask := uint32(linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID)
@@ -580,8 +557,181 @@ func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
// OpenAt implements vfs.FilesystemImpl.OpenAt.
func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
- //TODO(b/159261227): Implement OpenAt.
- return nil, nil
+ // Verity fs is read-only.
+ if opts.Flags&(linux.O_WRONLY|linux.O_CREAT) != 0 {
+ return nil, syserror.EROFS
+ }
+
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+
+ start := rp.Start().Impl().(*dentry)
+ if rp.Done() {
+ return start.openLocked(ctx, rp, &opts)
+ }
+
+afterTrailingSymlink:
+ parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
+ if err != nil {
+ return nil, err
+ }
+
+ // Check for search permission in the parent directory.
+ if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
+ return nil, err
+ }
+
+ // Open existing child or follow symlink.
+ parent.dirMu.Lock()
+ child, err := fs.stepLocked(ctx, rp, parent, false /*mayFollowSymlinks*/, &ds)
+ parent.dirMu.Unlock()
+ if err != nil {
+ return nil, err
+ }
+ if child.isSymlink() && rp.ShouldFollowSymlink() {
+ target, err := child.readlink(ctx)
+ if err != nil {
+ return nil, err
+ }
+ if err := rp.HandleSymlink(target); err != nil {
+ return nil, err
+ }
+ start = parent
+ goto afterTrailingSymlink
+ }
+ return child.openLocked(ctx, rp, &opts)
+}
+
+// Preconditions: fs.renameMu must be locked.
+func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions) (*vfs.FileDescription, error) {
+ // Users should not open the Merkle tree files. Those are for verity fs
+ // use only.
+ if strings.Contains(d.name, merklePrefix) {
+ return nil, syserror.EPERM
+ }
+ ats := vfs.AccessTypesForOpenFlags(opts)
+ if err := d.checkPermissions(rp.Credentials(), ats); err != nil {
+ return nil, err
+ }
+
+ // Verity fs is read-only.
+ if ats&vfs.MayWrite != 0 {
+ return nil, syserror.EROFS
+ }
+
+ // Get the path to the target file. This is only used to provide path
+ // information in failure case.
+ path, err := d.fs.vfsfs.VirtualFilesystem().PathnameWithDeleted(ctx, d.fs.rootDentry.lowerVD, d.lowerVD)
+ if err != nil {
+ return nil, err
+ }
+
+ // Open the file in the underlying file system.
+ lowerFD, err := rp.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.lowerVD,
+ Start: d.lowerVD,
+ }, opts)
+
+ // The file should exist, as we succeeded in finding its dentry. If it's
+ // missing, it indicates an unexpected modification to the file system.
+ if err != nil {
+ if err == syserror.ENOENT {
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("File %s expected but not found", path))
+ }
+ return nil, err
+ }
+
+ // lowerFD needs to be cleaned up if any error occurs. IncRef will be
+ // called if a verity FD is successfully created.
+ defer lowerFD.DecRef(ctx)
+
+ // Open the Merkle tree file corresponding to the current file/directory
+ // to be used later for verifying Read/Walk.
+ merkleReader, err := rp.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.lowerMerkleVD,
+ Start: d.lowerMerkleVD,
+ }, &vfs.OpenOptions{
+ Flags: linux.O_RDONLY,
+ })
+
+ // The Merkle tree file should exist, as we succeeded in finding its
+ // dentry. If it's missing, it indicates an unexpected modification to
+ // the file system.
+ if err != nil {
+ if err == syserror.ENOENT {
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Merkle file for %s expected but not found", path))
+ }
+ return nil, err
+ }
+
+ // merkleReader needs to be cleaned up if any error occurs. IncRef will
+ // be called if a verity FD is successfully created.
+ defer merkleReader.DecRef(ctx)
+
+ lowerFlags := lowerFD.StatusFlags()
+ lowerFDOpts := lowerFD.Options()
+ var merkleWriter *vfs.FileDescription
+ var parentMerkleWriter *vfs.FileDescription
+
+ // Only open the Merkle tree files for write if in allowRuntimeEnable
+ // mode.
+ if d.fs.allowRuntimeEnable {
+ merkleWriter, err = rp.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.lowerMerkleVD,
+ Start: d.lowerMerkleVD,
+ }, &vfs.OpenOptions{
+ Flags: linux.O_WRONLY | linux.O_APPEND,
+ })
+ if err != nil {
+ if err == syserror.ENOENT {
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Merkle file for %s expected but not found", path))
+ }
+ return nil, err
+ }
+ // merkleWriter is cleaned up if any error occurs. IncRef will
+ // be called if a verity FD is created successfully.
+ defer merkleWriter.DecRef(ctx)
+
+ parentMerkleWriter, err = rp.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.parent.lowerMerkleVD,
+ Start: d.parent.lowerMerkleVD,
+ }, &vfs.OpenOptions{
+ Flags: linux.O_WRONLY | linux.O_APPEND,
+ })
+ if err != nil {
+ if err == syserror.ENOENT {
+ parentPath, _ := d.fs.vfsfs.VirtualFilesystem().PathnameWithDeleted(ctx, d.fs.rootDentry.lowerVD, d.parent.lowerVD)
+ return nil, alertIntegrityViolation(err, fmt.Sprintf("Merkle file for %s expected but not found", parentPath))
+ }
+ return nil, err
+ }
+ // parentMerkleWriter is cleaned up if any error occurs. IncRef
+ // will be called if a verity FD is created successfully.
+ defer parentMerkleWriter.DecRef(ctx)
+ }
+
+ fd := &fileDescription{
+ d: d,
+ lowerFD: lowerFD,
+ merkleReader: merkleReader,
+ merkleWriter: merkleWriter,
+ parentMerkleWriter: parentMerkleWriter,
+ isDir: d.isDir(),
+ }
+
+ if err := fd.vfsfd.Init(fd, lowerFlags, rp.Mount(), &d.vfsd, &lowerFDOpts); err != nil {
+ return nil, err
+ }
+ lowerFD.IncRef()
+ merkleReader.IncRef()
+ if merkleWriter != nil {
+ merkleWriter.IncRef()
+ }
+ if parentMerkleWriter != nil {
+ parentMerkleWriter.IncRef()
+ }
+ return &fd.vfsfd, err
}
// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt.
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index 249cc1341..3e0bcd02b 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -22,6 +22,7 @@
package verity
import (
+ "fmt"
"strconv"
"sync/atomic"
@@ -29,7 +30,6 @@ import (
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/marshal/primitive"
-
"gvisor.dev/gvisor/pkg/merkletree"
"gvisor.dev/gvisor/pkg/sentry/arch"
fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
@@ -135,6 +135,16 @@ func (FilesystemType) Name() string {
return Name
}
+// alertIntegrityViolation alerts a violation of integrity, which usually means
+// unexpected modification to the file system is detected. In
+// noCrashOnVerificationFailure mode, it returns an error, otherwise it panic.
+func alertIntegrityViolation(err error, msg string) error {
+ if noCrashOnVerificationFailure {
+ return err
+ }
+ panic(msg)
+}
+
// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
iopts, ok := opts.InternalData.(InternalFilesystemOptions)
@@ -204,15 +214,12 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
return nil, nil, err
}
} else if err != nil {
- // Failed to get dentry for the root Merkle file. This indicates
- // an attack that removed/renamed the root Merkle file, or it's
- // never generated.
- if noCrashOnVerificationFailure {
- fs.vfsfs.DecRef(ctx)
- d.DecRef(ctx)
- return nil, nil, err
- }
- panic("Failed to find root Merkle file")
+ // Failed to get dentry for the root Merkle file. This
+ // indicates an unexpected modification that removed/renamed
+ // the root Merkle file, or it's never generated.
+ fs.vfsfs.DecRef(ctx)
+ d.DecRef(ctx)
+ return nil, nil, alertIntegrityViolation(err, "Failed to find root Merkle file")
}
d.lowerMerkleVD = lowerMerkleVD
@@ -550,7 +557,7 @@ func (fd *fileDescription) enableVerity(ctx context.Context, uio usermem.IO, arg
defer verityMu.Unlock()
if fd.lowerFD == nil || fd.merkleReader == nil || fd.merkleWriter == nil || fd.parentMerkleWriter == nil {
- panic("Unexpected verity fd: missing expected underlying fds")
+ return 0, alertIntegrityViolation(syserror.EIO, "Unexpected verity fd: missing expected underlying fds")
}
rootHash, dataSize, err := fd.generateMerkle(ctx)
@@ -618,6 +625,54 @@ func (fd *fileDescription) Ioctl(ctx context.Context, uio usermem.IO, args arch.
}
}
+// PRead implements vfs.FileDescriptionImpl.PRead.
+func (fd *fileDescription) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
+ // No need to verify if the file is not enabled yet in
+ // allowRuntimeEnable mode.
+ if fd.d.fs.allowRuntimeEnable && len(fd.d.rootHash) == 0 {
+ return fd.lowerFD.PRead(ctx, dst, offset, opts)
+ }
+
+ // dataSize is the size of the whole file.
+ dataSize, err := fd.merkleReader.GetXattr(ctx, &vfs.GetXattrOptions{
+ Name: merkleSizeXattr,
+ Size: sizeOfInt32,
+ })
+
+ // The Merkle tree file for the child should have been created and
+ // contains the expected xattrs. If the xattr does not exist, it
+ // indicates unexpected modifications to the file system.
+ if err == syserror.ENODATA {
+ return 0, alertIntegrityViolation(err, fmt.Sprintf("Failed to get xattr %s: %v", merkleSizeXattr, err))
+ }
+ if err != nil {
+ return 0, err
+ }
+
+ // The dataSize xattr should be an integer. If it's not, it indicates
+ // unexpected modifications to the file system.
+ size, err := strconv.Atoi(dataSize)
+ if err != nil {
+ return 0, alertIntegrityViolation(err, fmt.Sprintf("Failed to convert xattr %s to int: %v", merkleSizeXattr, err))
+ }
+
+ dataReader := vfs.FileReadWriteSeeker{
+ FD: fd.lowerFD,
+ Ctx: ctx,
+ }
+
+ merkleReader := vfs.FileReadWriteSeeker{
+ FD: fd.merkleReader,
+ Ctx: ctx,
+ }
+
+ n, err := merkletree.Verify(dst.Writer(ctx), &dataReader, &merkleReader, int64(size), offset, dst.NumBytes(), fd.d.rootHash, false /* dataAndTreeInSameFile */)
+ if err != nil {
+ return 0, alertIntegrityViolation(syserror.EINVAL, fmt.Sprintf("Verification failed: %v", err))
+ }
+ return n, err
+}
+
// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
func (fd *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block)
generated by cgit v1.2.3 (git 2.39.1) at 2025-02-27 19:33:35 +0000