From 1f4e554168a25151e0c21375921376fd2b6c53de Mon Sep 17 00:00:00 2001 From: Jakob Unterwurzacher Date: Sat, 4 Jul 2020 21:42:04 +0200 Subject: v2api: merge openBackingDir into root_node.go --- internal/fusefrontend/root_node.go | 60 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) (limited to 'internal/fusefrontend/root_node.go') diff --git a/internal/fusefrontend/root_node.go b/internal/fusefrontend/root_node.go index 2689e05..cf23169 100644 --- a/internal/fusefrontend/root_node.go +++ b/internal/fusefrontend/root_node.go @@ -2,6 +2,8 @@ package fusefrontend import ( "os" + "path/filepath" + "strings" "sync" "sync/atomic" "syscall" @@ -185,3 +187,61 @@ func (rn *RootNode) openWriteOnlyFile(dirfd int, cName string, newFlags int) (rw }() return syscallcompat.Openat(dirfd, cName, newFlags, 0) } + +// openBackingDir opens the parent ciphertext directory of plaintext path +// "relPath". It returns the dirfd (opened with O_PATH) and the encrypted +// basename. +// +// The caller should then use Openat(dirfd, cName, ...) and friends. +// For convenience, if relPath is "", cName is going to be ".". +// +// openBackingDir is secure against symlink races by using Openat and +// ReadDirIVAt. +func (rn *RootNode) openBackingDir(relPath string) (dirfd int, cName string, err error) { + dirRelPath := nametransform.Dir(relPath) + // With PlaintextNames, we don't need to read DirIVs. Easy. + if rn.args.PlaintextNames { + dirfd, err = syscallcompat.OpenDirNofollow(rn.args.Cipherdir, dirRelPath) + if err != nil { + return -1, "", err + } + // If relPath is empty, cName is ".". + cName = filepath.Base(relPath) + return dirfd, cName, nil + } + // Open cipherdir (following symlinks) + dirfd, err = syscall.Open(rn.args.Cipherdir, syscall.O_DIRECTORY|syscallcompat.O_PATH, 0) + if err != nil { + return -1, "", err + } + // If relPath is empty, cName is ".". + if relPath == "" { + return dirfd, ".", nil + } + // Walk the directory tree + parts := strings.Split(relPath, "/") + for i, name := range parts { + iv, err := nametransform.ReadDirIVAt(dirfd) + if err != nil { + syscall.Close(dirfd) + return -1, "", err + } + cName, err = rn.nameTransform.EncryptAndHashName(name, iv) + if err != nil { + syscall.Close(dirfd) + return -1, "", err + } + // Last part? We are done. + if i == len(parts)-1 { + break + } + // Not the last part? Descend into next directory. + dirfd2, err := syscallcompat.Openat(dirfd, cName, syscall.O_NOFOLLOW|syscall.O_DIRECTORY|syscallcompat.O_PATH, 0) + syscall.Close(dirfd) + if err != nil { + return -1, "", err + } + dirfd = dirfd2 + } + return dirfd, cName, nil +} -- cgit v1.2.3