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Re: [RFC v4 06/31] richacl: In-memory representation and helper functions

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Hi Andreas,

>> I'm wondering if the size of an ace should be dynamic,
>> which might make it possible to support other ace types
>> in future. E.g. supporting other identities like 128-bit values
>> to make it easier to map Windows SIDS.
> 
> I'm working on additionally supporting unmapped user@domain and
> group@domain identifier strings; we have to deal with that case in the
> nfs client; that may be useful for Samba as well.

Can this be any string? So would
"S-1-5-21-4052121579-2079768045-1474639452-1001" also work?

How would the current thread/process get a "token" that would match such
an ace?

>> Even without 128-bit ids, it would be very useful to mark an
>> ace so that it applies to a uid or gid at the same time.
>> This would reduce the size of the ace list when Samba uses
>> IDMAP_TYPE_BOTH, which means a SID is mapped to a unix id, which
>> is user (uid) and group (gid) at the same time. This feature is required
>> in order to support SID-Histories on accounts.
>> Currently Samba needs to add two aces (one uid and one gid)
>> in order to represent one Windows ace.
> 
> It's not clear to me if supporting this would be a good idea right now.
> The kernel would have to treat each such entry like two separate entries
> internally. How would we map a combined user-space "uid + gid"
> number to a kernel uid and gid since it could map to two distinct
> numbers there?

No, the numeric value is the same.

I think richacl_permission() is the only place that requires any action.

	richacl_for_each_entry(ace, acl) {
		unsigned int ace_mask = ace->e_mask;

		if (richace_is_inherit_only(ace))
			continue;
		if (richace_is_owner(ace)) {
			if (!uid_eq(current_fsuid(), inode->i_uid))
				continue;
		} else if (richace_is_group(ace)) {
			if (!in_owning_group)
				continue;
+		} else if (richace_is_unix_both(ace)) {
+			kuid_t uid = current_fsuid();
+
+			if (!uid_eq(uid, ace->e_id.xid) && !in_group_p(ace->e_id.xid))
+				continue;
		} else if (richace_is_unix_user(ace)) {
			kuid_t uid = current_fsuid();

			if (!uid_eq(uid, ace->e_id.uid))
				continue;
		} else if (richace_is_unix_group(ace)) {
			if (!in_group_p(ace->e_id.gid))
				continue;
		} else
			goto entry_matches_everyone;

In general shouldn't kuid_t uid = current_fsuid(); be at the top of the
function just once?

>> I haven't looked at the claims based acls on Windows, but it would be
>> good if the new infrastructure is dynamic enough to support something
>> like that in a future version.
> 
> I don't know, I have yet to see a use case that isn't totally crazy.

Ok, I found the a_version in struct richacl_xattr.

metze

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[RFC v4 00/31] Richacls Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 20/31] richacl: acl editing helper functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 22/31] richacl: Propagate everyone@ permissions to other aces Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 23/31] richacl: Set the owner permissions to the owner mask Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 04/31] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 26/31] richacl: Apply the file masks to a richacl Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:00 +0200
  [RFC v4 19/31] ext4: Add richacl feature flag Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 18/31] ext4: Add richacl support Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 14/31] richacl: Create-time inheritance Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 08/31] richacl: Compute maximum file masks from an acl Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 25/31] richacl: Isolate the owner and group classes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 06/31] richacl: In-memory representation and helper functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
    Re: [RFC v4 06/31] richacl: In-memory representation and helper functions "Stefan (metze) Metzmacher" <metze@samba.org> - 2015-06-25 23:50 +0200
  [RFC v4 03/31] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 16/31] richacl: xattr mapping functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 05/31] vfs: Add permission flags for setting file attributes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 31/31] nfsd: Add support for the v4.1 dacl attribute Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 09/31] richacl: Update the file masks in chmod() Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 12/31] vfs: Cache richacl in struct inode Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 30/31] nfsd: Add richacl support Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 11/31] vfs: Cache base_acl objects in inodes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 07/31] richacl: Permission mapping functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 13/31] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 01/31] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 17/31] vfs: Add richacl permission checking Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200
  [RFC v4 15/31] richacl: Automatic Inheritance Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-06-25 00:10 +0200

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