Only root is allowed to change the high 16 bits. The TODO entry says
otherwise, but that must be a mistake. For reference, see the glibc
sources, sysdeps/mach/hurd/bits/stat.h.
* libdiskfs/file-chflags.c (diskfs_S_file_chflags): Add permission
check.
* TODO (libdiskfs): Remove entry.
---
TODO | 2 --
libdiskfs/file-chflags.c | 6 ++++++
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/TODO b/TODO
index d2500dc..0387e9f 100644
--- a/TODO
+++ b/TODO
@@ -108,8 +108,6 @@ See `tasks', the exported task list.
Rename the rest to libhurdutil or somesuch.
** libdiskfs
-*** file_chflags does not do proper permission checking (non-root isn't
- supposed to be able to change the low bits)
*** Add the short-circuited-but-not-builtin translator startup code from
dir-lookup to fsys_getroot. Compare and match carefully these two
routines and then share common code.
diff --git a/libdiskfs/file-chflags.c b/libdiskfs/file-chflags.c
index 01dc495..9642c3c 100644
--- a/libdiskfs/file-chflags.c
+++ b/libdiskfs/file-chflags.c
@@ -25,6 +25,12 @@ diskfs_S_file_chflags (struct protid *cred,
{
CHANGE_NODE_FIELD (cred,
({
+ if (flags & 0xffff0000
+ && ! idvec_contains (cred->user->uids, 0))
+ /* Only root is allowed to change the high 16
+ bits. */
+ return EPERM;
+
err = fshelp_isowner (&np->dn_stat, cred->user);
if (!err)
err = diskfs_validate_flags_change (np, flags);
--
2.0.0
