From f20e63e31b56784c596897e86f03441f9d05f567 Mon Sep 17 00:00:00 2001 From: Fabricio Voznika Date: Thu, 6 Aug 2020 18:13:55 -0700 Subject: Add LinkAt support to gofer Updates #1198 PiperOrigin-RevId: 325350818 --- pkg/sentry/fsimpl/gofer/filesystem.go | 26 ++++++++++++++++++++++++-- pkg/sentry/fsimpl/gofer/gofer.go | 2 -- 2 files changed, 24 insertions(+), 4 deletions(-) (limited to 'pkg/sentry/fsimpl/gofer') diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index e6af37d0d..582b744bb 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -15,6 +15,7 @@ package gofer import ( + "math" "sync" "sync/atomic" @@ -724,8 +725,29 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs. if rp.Mount() != vd.Mount() { return syserror.EXDEV } - // 9P2000.L supports hard links, but we don't. - return syserror.EPERM + d := vd.Dentry().Impl().(*dentry) + if d.isDir() { + return syserror.EPERM + } + gid := auth.KGID(atomic.LoadUint32(&d.gid)) + uid := auth.KUID(atomic.LoadUint32(&d.uid)) + mode := linux.FileMode(atomic.LoadUint32(&d.mode)) + if err := vfs.MayLink(rp.Credentials(), mode, uid, gid); err != nil { + return err + } + if d.nlink == 0 { + return syserror.ENOENT + } + if d.nlink == math.MaxUint32 { + return syserror.EMLINK + } + if err := parent.file.link(ctx, d.file, childName); err != nil { + return err + } + + // Success! + atomic.AddUint32(&d.nlink, 1) + return nil }, nil) } diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index 2e5575d8d..6ae796c6d 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -558,8 +558,6 @@ type dentry struct { // filesystem.renameMu. name string - // We don't support hard links, so each dentry maps 1:1 to an inode. - // file is the unopened p9.File that backs this dentry. file is immutable. // // If file.isNil(), this dentry represents a synthetic file, i.e. a file -- cgit v1.2.3