diff options
Diffstat (limited to 'pkg/sentry/fsimpl/kernfs/kernfs.go')
| -rw-r--r-- | pkg/sentry/fsimpl/kernfs/kernfs.go | 67 |
1 files changed, 64 insertions, 3 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go index 0e2867d49..90c8b75d1 100644 --- a/pkg/sentry/fsimpl/kernfs/kernfs.go +++ b/pkg/sentry/fsimpl/kernfs/kernfs.go @@ -66,6 +66,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" ) // Filesystem mostly implements vfs.FilesystemImpl for a generic in-memory @@ -542,6 +543,63 @@ func (d *Dentry) FSLocalPath() string { return b.String() } +// WalkDentryTree traverses p in the dentry tree for this filesystem. Note that +// this only traverses the dentry tree and is not a general path traversal. No +// symlinks and dynamic children are resolved, and no permission checks are +// performed. The caller is responsible for ensuring the returned Dentry exists +// for an appropriate lifetime. +// +// p is interpreted starting at d, and may be absolute or relative (absolute vs +// relative paths both refer to the same target here, since p is absolute from +// d). p may contain "." and "..", but will not allow traversal above d (similar +// to ".." at the root dentry). +// +// This is useful for filesystem internals, where the filesystem may not be +// mounted yet. For a mounted filesystem, use GetDentryAt. +func (d *Dentry) WalkDentryTree(ctx context.Context, vfsObj *vfs.VirtualFilesystem, p fspath.Path) (*Dentry, error) { + d.fs.mu.RLock() + defer d.fs.processDeferredDecRefs(ctx) + defer d.fs.mu.RUnlock() + + target := d + + for pit := p.Begin; pit.Ok(); pit = pit.Next() { + pc := pit.String() + + switch { + case target == nil: + return nil, syserror.ENOENT + case pc == ".": + // No-op, consume component and continue. + case pc == "..": + if target == d { + // Don't let .. traverse above the start point of the walk. + continue + } + target = target.parent + // Parent doesn't need revalidation since we revalidated it on the + // way to the child, and we're still holding fs.mu. + default: + var err error + + d.dirMu.Lock() + target, err = d.fs.revalidateChildLocked(ctx, vfsObj, target, pc, target.children[pc]) + d.dirMu.Unlock() + + if err != nil { + return nil, err + } + } + } + + if target == nil { + return nil, syserror.ENOENT + } + + target.IncRef() + return target, nil +} + // The Inode interface maps filesystem-level operations that operate on paths to // equivalent operations on specific filesystem nodes. // @@ -667,12 +725,15 @@ type inodeDirectory interface { // RmDir removes an empty child directory from this directory // inode. Implementations must update the parent directory's link count, // if required. Implementations are not responsible for checking that child - // is a directory, checking for an empty directory. + // is a directory, or checking for an empty directory. RmDir(ctx context.Context, name string, child Inode) error // Rename is called on the source directory containing an inode being - // renamed. child should point to the resolved child in the source - // directory. + // renamed. child points to the resolved child in the source directory. + // dstDir is guaranteed to be a directory inode. + // + // On a successful call to Rename, the caller updates the dentry tree to + // reflect the name change. // // Precondition: Caller must serialize concurrent calls to Rename. Rename(ctx context.Context, oldname, newname string, child, dstDir Inode) error |