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vfs_acl_xattr: objects without NT ACL xattr

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Even with "ignore system acls" set to "yes", for objects without NT ACL
xattr we use the underlying filesystem permissions to construct an NT
ACL. This can result in *very* unexpected permissions, eg:

- a directory with the following ACL:

$ ./bin/smbcacls -Uslow%pass //localhost/normal ""
REVISION:1
CONTROL:SR|DP
OWNER:SLOW\slow
GROUP:Unix Group\root
ACL:SLOW\slow:ALLOWED/0x0/FULL

So only one non-inheritable(!) ACE.

- creating a subdirectory:

$ ./bin/smbclient -Uslow%pass //localhost/normal -c "mkdir dir1"

- checking whether there's an ACL xattr:

$ getfattr -m "" /Volumes/normal/dir1
getfattr: Removing leading '/' from absolute path names
system.posix_acl_access
system.posix_acl_default
user.DOSATTRIB

So there isn't an ACL xattr, because there where no inheritable ACEs on
the parent folder.

- reading the new subdirectories ACL:

$ ./bin/smbcacls -Uslow%pass //localhost/normal "dir1"
REVISION:1
CONTROL:SR|DP
OWNER:SLOW\slow
GROUP:Unix Group\slow
ACL:SLOW\slow:ALLOWED/0x0/FULL
ACL:Unix Group\slow:ALLOWED/0x0/READ
ACL:Everyone:ALLOWED/0x0/READ
ACL:NT Authority\SYSTEM:ALLOWED/0x0/FULL

The ACES for "SLOW\slow", "Unix Group\slow" and "Everyone" are coming
from the underlying filesystem. This is the problem.

- Windows assigns the following ACL in this situation:

$ ./bin/smbcacls -UAdministrator%Passw0rd //10.10.10.14/data "dir"
REVISION:1
CONTROL:SR|PD|DI|DP
OWNER:VORDEFINIERT\Administratoren
GROUP:WIN2008R2\Domänen-Benutzer
ACL:WIN2008R2\Administrator:ALLOWED/0x0/FULL

$ ./bin/smbclient -UAdministrator%Passw0rd //10.10.10.14/data -c "mkdir dir\dir1"

$ ./bin/smbcacls -UAdministrator%Passw0rd //10.10.10.14/data "dir\dir1"
REVISION:1
CONTROL:SR|DI|DP
OWNER:VORDEFINIERT\Administratoren
GROUP:WIN2008R2\Domänen-Benutzer
ACL:VORDEFINIERT\Administratoren:ALLOWED/0x0/FULL
ACL:NT-AUTORITÄT\SYSTEM:ALLOWED/0x0/FULL

By changing make_default_filesystem_acl() to only adds user and system
ACE to the ACL of objects that lack an ACL xattr, we match Windows
behaviour:

$ ./bin/smbclient -Uslow%pass //localhost/normal -c "mkdir dir2"

$ ./bin/smbcacls -Uslow%pass //localhost/normal "dir2"
REVISION:1
CONTROL:SR|DP
OWNER:SLOW\slow
GROUP:Unix Group\slow
ACL:SLOW\slow:ALLOWED/0x0/FULL
ACL:NT Authority\SYSTEM:ALLOWED/0x0/FULL

Bug: https://bugzilla.samba.org/show_bug.cgi?id=12028

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Tue Jul 19 10:22:05 CEST 2016 on sn-devel-144
This commit is contained in:
Ralph Boehme 2016-07-15 17:48:19 +02:00
parent afc2417b10
commit 961c4b591b
1 changed files with 5 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
source3/modules/vfs_acl_common.c
View File

@ -24,6 +24,7 @@
#include "../libcli/security/security.h"
#include "../librpc/gen_ndr/ndr_security.h"
#include "../lib/util/bitmap.h"
#include "passdb/lookup_sid.h"
static NTSTATUS create_acl_blob(const struct security_descriptor *psd,
DATA_BLOB *pblob,
@ -378,12 +379,10 @@ static NTSTATUS make_default_filesystem_acl(TALLOC_CTX *ctx,
gid_to_sid(&group_sid, psbuf->st_ex_gid);
/*
We provide up to 4 ACEs
- Owner
- Group
- Everyone
- NT System
*/
* We provide 2 ACEs:
* - Owner
* - NT System
*/
if (mode & S_IRUSR) {
if (mode & S_IWUSR) {
@ -403,39 +402,6 @@ static NTSTATUS make_default_filesystem_acl(TALLOC_CTX *ctx,
0);
idx++;
access_mask = 0;
if (mode & S_IRGRP) {
access_mask |= SEC_RIGHTS_FILE_READ | SEC_FILE_EXECUTE;
}
if (mode & S_IWGRP) {
/* note that delete is not granted - this matches posix behaviour */
access_mask |= SEC_RIGHTS_FILE_WRITE;
}
if (access_mask) {
init_sec_ace(&aces[idx],
&group_sid,
SEC_ACE_TYPE_ACCESS_ALLOWED,
access_mask,
0);
idx++;
}
access_mask = 0;
if (mode & S_IROTH) {
access_mask |= SEC_RIGHTS_FILE_READ | SEC_FILE_EXECUTE;
}
if (mode & S_IWOTH) {
access_mask |= SEC_RIGHTS_FILE_WRITE;
}
if (access_mask) {
init_sec_ace(&aces[idx],
&global_sid_World,
SEC_ACE_TYPE_ACCESS_ALLOWED,
access_mask,
0);
idx++;
}
init_sec_ace(&aces[idx],
&global_sid_System,
SEC_ACE_TYPE_ACCESS_ALLOWED,