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fusefrontend: make RemoveXAttr() symlink-safe

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Uses /proc/self/fd on Linux.
This commit is contained in:
Jakob Unterwurzacher 2018-11-11 18:04:44 +01:00
parent 810d2a8b47
commit d3ae87fa2b
3 changed files with 36 additions and 10 deletions
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15
internal/fusefrontend/xattr.go
View File

@ -68,21 +68,18 @@ func (fs *FS) SetXAttr(relPath string, attr string, data []byte, flags int, cont
// RemoveXAttr - FUSE call.
//
// TODO: Make symlink-safe. Blocker: package xattr does not provide
// fremovexattr(2).
func (fs *FS) RemoveXAttr(path string, attr string, context *fuse.Context) fuse.Status {
if fs.isFiltered(path) {
// This function is symlink-safe on Linux.
// Darwin does not have fremovexattr(2) nor /proc/self/fd. How to implement this
// on Darwin in a symlink-safe way?
func (fs *FS) RemoveXAttr(relPath string, attr string, context *fuse.Context) fuse.Status {
if fs.isFiltered(relPath) {
return fuse.EPERM
}
if disallowedXAttrName(attr) {
return _EOPNOTSUPP
}
cPath, err := fs.getBackingPath(path)
if err != nil {
return fuse.ToStatus(err)
}
cAttr := fs.encryptXattrName(attr)
return unpackXattrErr(xattr.LRemove(cPath, cAttr))
return fs.removeXAttr(relPath, cAttr, context)
}
// ListXAttr - FUSE call. Lists extended attributes on the file at "path".

16
internal/fusefrontend/xattr_darwin.go
View File

@ -18,7 +18,8 @@ func filterXattrSetFlags(flags int) int {
return flags &^ xattr.XATTR_NOSECURITY
}
// This function is NOT symlink-safe because Darwin lacks fgetxattr().
// This function is NOT symlink-safe because Darwin lacks
// both fgetxattr() and /proc/self/fd.
func (fs *FS) getXattr(relPath string, cAttr string, context *fuse.Context) ([]byte, fuse.Status) {
cPath, err := fs.getBackingPath(relPath)
if err != nil {
@ -31,6 +32,8 @@ func (fs *FS) getXattr(relPath string, cAttr string, context *fuse.Context) ([]b
return cData, fuse.OK
}
// This function is NOT symlink-safe because Darwin lacks
// both fsetxattr() and /proc/self/fd.
func (fs *FS) setXattr(relPath string, cAttr string, cData []byte, flags int, context *fuse.Context) fuse.Status {
cPath, err := fs.getBackingPath(relPath)
if err != nil {
@ -39,3 +42,14 @@ func (fs *FS) setXattr(relPath string, cAttr string, cData []byte, flags int, co
err = xattr.LSetWithFlags(cPath, cAttr, cData, flags)
return unpackXattrErr(err)
}
// This function is NOT symlink-safe because Darwin lacks
// both fremovexattr() and /proc/self/fd.
func (fs *FS) removeXAttr(relPath string, cAttr string, context *fuse.Context) fuse.Status {
cPath, err := fs.getBackingPath(relPath)
if err != nil {
return fuse.ToStatus(err)
}
err = xattr.LRemove(cPath, cAttr)
return unpackXattrErr(err)
}

15
internal/fusefrontend/xattr_linux.go
View File

@ -84,3 +84,18 @@ func (fs *FS) setXattr(relPath string, cAttr string, cData []byte, flags int, co
err := xattr.SetWithFlags(procFd(fd), cAttr, cData, flags)
return unpackXattrErr(err)
}
// removeXAttr - remove encrypted xattr name "cAttr" from
// plaintext path "relPath".
//
// This function is symlink-safe on Linux by using /proc/self/fd.
func (fs *FS) removeXAttr(relPath string, cAttr string, context *fuse.Context) fuse.Status {
file, fd, status := fs.getFileFd(relPath, context)
if !status.Ok() {
return status
}
defer file.Release()
err := xattr.Remove(procFd(fd), cAttr)
return unpackXattrErr(err)
}