Windows 10 brought security descriptors which contain ACE's related to
new ways of accessing files or directories. These ACE are now accepted
with minimal consistency checks. They are still ignored for translating
permissions and for Windows-type inheritance.
ntfs_valid_sid() required that the subauthority count be between 1 and 8
inclusively. However, Windows permits more than 8 subauthorities as well
as 0 subauthorities:
- The install.wim file for the latest Windows 10 build contains a file
whose DACL contains a SID with 10 subauthorities.
ntfs_set_ntfs_acl() was failing on this file.
- The IsValidSid() function on Windows returns true for subauthority
less than or equal to 15, including 0.
There was actually already a another SID validation function that had the
Windows-compatible behavior, so I merged the two together.
Contributed by Eric Biggers
When the owner and the group of a file have the same SID, and permissions
for the group is the same as permissions for other, no ACE is needed for
the group.
When Posix ACLs are used, the umask is ignored and the initial permissions
of created files are taken for the parent directory. However the umask
should still be used when the Posix ACLs are not enabled in the mount
options.
Since Vista, the standard directory /Users/Public which should be accessed
by any user is actually restricted to a few group of users, among them
the interactive ones. To make this directory accessible without using
the Posix ACLs, all Linux users are considered as interactive.
However, when Posix ACLs are used, users supposed to be interactive have
to be put into a secondary group mapped to the equivalent Windows group.
The Windows-type inheritance of an ACE may imply creating two ACE's : one
for access and one for further inheritance. The conditions for doing so,
and the flags set on created ACE were sometimes wrong.
Note : the rules have been derived from testing multiple situations, but
there still are some gray cases.
Since Vista, Windows defines a /Users/Public directory supposed to be
public, but actually only allowed to a few user categories (interactive,
batch, etc.) This patch makes possible to create equivalent Unix groups
and group users the same way as in Windows. Posix ACLs have to be enabled
for access to /Users/Public to be allowed to several groups.
Windows server 2012 apparently uses files with no ACEs in their DACL,
thus denying any access to any process except system backup.
Such DACLs should however be considered valid.
Accept security descriptors in which the SACL is present though it does not
contain any ACE. Such security descriptors have been found in Windows
installation files.
Under some conditions, Windows defines an ACL inheritance for an
unidentified authenticated user. With this patch, such an unidentified
user is treated as any user (same as "world").
Jean-Pierre André
Erik Larsson
jpandre