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-rwxr-xr-xpkg/sentry/vfs/resolving_path.go40
1 files changed, 30 insertions, 10 deletions
diff --git a/pkg/sentry/vfs/resolving_path.go b/pkg/sentry/vfs/resolving_path.go
index 621f5a6f8..d580fd39e 100755
--- a/pkg/sentry/vfs/resolving_path.go
+++ b/pkg/sentry/vfs/resolving_path.go
@@ -85,11 +85,11 @@ func init() {
// so error "constants" are really mutable vars, necessitating somewhat
// expensive interface object comparisons.
-type resolveMountRootError struct{}
+type resolveMountRootOrJumpError struct{}
// Error implements error.Error.
-func (resolveMountRootError) Error() string {
- return "resolving mount root"
+func (resolveMountRootOrJumpError) Error() string {
+ return "resolving mount root or jump"
}
type resolveMountPointError struct{}
@@ -274,7 +274,7 @@ func (rp *ResolvingPath) ResolveParent(d *Dentry) (*Dentry, error) {
// ... of non-root mount.
rp.nextMount = vd.mount
rp.nextStart = vd.dentry
- return nil, resolveMountRootError{}
+ return nil, resolveMountRootOrJumpError{}
}
// ... of root mount.
parent = d
@@ -385,11 +385,32 @@ func (rp *ResolvingPath) relpathPrepend(path fspath.Path) {
}
}
+// HandleJump is called when the current path component is a "magic" link to
+// the given VirtualDentry, like /proc/[pid]/fd/[fd]. If the calling Filesystem
+// method should continue path traversal, HandleMagicSymlink updates the path
+// component stream to reflect the magic link target and returns nil. Otherwise
+// it returns a non-nil error.
+//
+// Preconditions: !rp.Done().
+func (rp *ResolvingPath) HandleJump(target VirtualDentry) error {
+ if rp.symlinks >= linux.MaxSymlinkTraversals {
+ return syserror.ELOOP
+ }
+ rp.symlinks++
+ // Consume the path component that represented the magic link.
+ rp.Advance()
+ // Unconditionally return a resolveMountRootOrJumpError, even if the Mount
+ // isn't changing, to force restarting at the new Dentry.
+ target.IncRef()
+ rp.nextMount = target.mount
+ rp.nextStart = target.dentry
+ return resolveMountRootOrJumpError{}
+}
+
func (rp *ResolvingPath) handleError(err error) bool {
switch err.(type) {
- case resolveMountRootError:
- // Switch to the new Mount. We hold references on the Mount and Dentry
- // (from VFS.getMountpointAt()).
+ case resolveMountRootOrJumpError:
+ // Switch to the new Mount. We hold references on the Mount and Dentry.
rp.decRefStartAndMount()
rp.mount = rp.nextMount
rp.start = rp.nextStart
@@ -407,9 +428,8 @@ func (rp *ResolvingPath) handleError(err error) bool {
return true
case resolveMountPointError:
- // Switch to the new Mount. We hold a reference on the Mount (from
- // VFS.getMountAt()), but borrow the reference on the mount root from
- // the Mount.
+ // Switch to the new Mount. We hold a reference on the Mount, but
+ // borrow the reference on the mount root from the Mount.
rp.decRefStartAndMount()
rp.mount = rp.nextMount
rp.start = rp.nextMount.root