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fusefrontend: make ListXAttr symlink-safe on Linux

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Uses /proc/self/fd.
This commit is contained in:
Jakob Unterwurzacher 2018-11-11 18:27:37 +01:00
parent d3ae87fa2b
commit c3adf9729d
3 changed files with 47 additions and 12 deletions
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21
internal/fusefrontend/xattr.go
View File

@ -82,21 +82,18 @@ func (fs *FS) RemoveXAttr(relPath string, attr string, context *fuse.Context) fu
return fs.removeXAttr(relPath, cAttr, context)
}
// ListXAttr - FUSE call. Lists extended attributes on the file at "path".
// ListXAttr - FUSE call. Lists extended attributes on the file at "relPath".
//
// TODO: Make symlink-safe. Blocker: package xattr does not provide
// flistxattr(2).
func (fs *FS) ListXAttr(path string, context *fuse.Context) ([]string, fuse.Status) {
if fs.isFiltered(path) {
// This function is symlink-safe on Linux.
// Darwin does not have flistxattr(2) nor /proc/self/fd. How to implement this
// on Darwin in a symlink-safe way?
func (fs *FS) ListXAttr(relPath string, context *fuse.Context) ([]string, fuse.Status) {
if fs.isFiltered(relPath) {
return nil, fuse.EPERM
}
cPath, err := fs.getBackingPath(path)
if err != nil {
return nil, fuse.ToStatus(err)
}
cNames, err := xattr.LList(cPath)
if err != nil {
return nil, unpackXattrErr(err)
cNames, status := fs.listXAttr(relPath, context)
if !status.Ok() {
return nil, status
}
names := make([]string, 0, len(cNames))
for _, curName := range cNames {

14
internal/fusefrontend/xattr_darwin.go
View File

@ -53,3 +53,17 @@ func (fs *FS) removeXAttr(relPath string, cAttr string, context *fuse.Context) f
err = xattr.LRemove(cPath, cAttr)
return unpackXattrErr(err)
}
// This function is NOT symlink-safe because Darwin lacks
// both flistxattr() and /proc/self/fd.
func (fs *FS) listXAttr(relPath string, context *fuse.Context) ([]string, fuse.Status) {
cPath, err := fs.getBackingPath(relPath)
if err != nil {
return nil, fuse.ToStatus(err)
}
cNames, err := xattr.LList(cPath)
if err != nil {
return nil, unpackXattrErr(err)
}
return cNames, fuse.OK
}

24
internal/fusefrontend/xattr_linux.go
View File

@ -99,3 +99,27 @@ func (fs *FS) removeXAttr(relPath string, cAttr string, context *fuse.Context) f
err := xattr.Remove(procFd(fd), cAttr)
return unpackXattrErr(err)
}
// listXAttr - list encrypted xattr names on plaintext path "relPath".
//
// This function is symlink-safe on Linux by using /proc/self/fd.
func (fs *FS) listXAttr(relPath string, context *fuse.Context) ([]string, fuse.Status) {
file, fd, status := fs.getFileFd(relPath, context)
if !status.Ok() {
// If relPath is a symlink, getFileFd fails with ELOOP. As setXattr()
// also fails with ELOOP, there is no way to set xattrs on symlinks,
// and we can assume that the file does not have any.
if status == fuse.Status(syscall.ELOOP) {
return nil, fuse.OK
}
return nil, status
}
defer file.Release()
cNames, err := xattr.List(procFd(fd))
if err != nil {
status := unpackXattrErr(err)
return nil, status
}
return cNames, fuse.OK
}