https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=ac4648c13eab48d1e7626d272ae47839da579429
commit ac4648c13eab48d1e7626d272ae47839da579429
Author: Corinna Vinschen <cori...@vinschen.de>
Date: Thu Jan 28 22:05:49 2016 +0100
Treat ACLs with extra ACEs for Admins and SYSTEM like a trivial ACL
POSIX.1e requires that chmod changes the MASK rather than the
GROUP_OBJ value if the ACL is non-trivial.
On Windows, especially on home machines, a standard ACL often
consists of entries for the user, maybe the group, and additional
entries for SYSTEM and the Administrators group. A user calling
chmod on a file with bog standard Windows perms usually expects
that chmod changes the GROUP_OBJ perms, but given the rules from
POSIX.1e we can't do that.
However, since we already treat Admins and SYSTEM special in a
ACL (they are not used in MASK computations) we go a step in the
Windows direction to follow user expectations. If an ACL only
consists of the three POSIX permissions, plus entries for Admins
and SYSTEM *only*, then we change the permissions of the GROUP_OBJ
entry *and* the MASK entry.
* fhandler_disk_file.cc (fhandler_disk_file::chmod): Drop unused
code. Add special handling for a "standard" Windows ACL. Add
comment to explain.
* sec_acl.cc (get_posix_access): Allow to return "standard-ness"
of an ACL to the caller. Add preceeding comment to explain a bit.
* security.h (get_posix_access): Align prototype.
Signed-off-by: Corinna Vinschen <cori...@vinschen.de>
Diff:
---
winsup/cygwin/fhandler_disk_file.cc | 30 +++++++++++++++---------------
winsup/cygwin/sec_acl.cc | 18 ++++++++++++++----
winsup/cygwin/security.h | 2 +-
3 files changed, 30 insertions(+), 20 deletions(-)
diff --git a/winsup/cygwin/fhandler_disk_file.cc
b/winsup/cygwin/fhandler_disk_file.cc
index 4ee67e2..7d729e3 100644
--- a/winsup/cygwin/fhandler_disk_file.cc
+++ b/winsup/cygwin/fhandler_disk_file.cc
@@ -787,35 +787,35 @@ fhandler_disk_file::fchmod (mode_t mode)
gid_t gid;
tmp_pathbuf tp;
aclent_t *aclp;
+ bool standard_acl = false;
int nentries, idx;
if (!get_file_sd (get_handle (), pc, sd, false))
{
aclp = (aclent_t *) tp.c_get ();
if ((nentries = get_posix_access (sd, NULL, &uid, &gid,
- aclp, MAX_ACL_ENTRIES)) >= 0)
+ aclp, MAX_ACL_ENTRIES,
+ &standard_acl)) >= 0)
{
/* Overwrite ACL permissions as required by POSIX 1003.1e
draft 17. */
aclp[0].a_perm = (mode >> 6) & S_IRWXO;
-#if 0
- /* Deliberate deviation from POSIX 1003.1e here. We're not
- writing CLASS_OBJ *or* GROUP_OBJ, but both. Otherwise we're
- going to be in constant trouble with user expectations. */
- if ((idx = searchace (aclp, nentries, GROUP_OBJ)) >= 0)
- aclp[idx].a_perm = (mode >> 3) & S_IRWXO;
- if (nentries > MIN_ACL_ENTRIES
- && (idx = searchace (aclp, nentries, CLASS_OBJ)) >= 0)
- aclp[idx].a_perm = (mode >> 3) & S_IRWXO;
-#else
+
/* POSIXly correct: If CLASS_OBJ is present, chmod only modifies
- CLASS_OBJ, not GROUP_OBJ. */
+ CLASS_OBJ, not GROUP_OBJ.
+
+ Deliberate deviation from POSIX 1003.1e: If the ACL is a
+ "standard" ACL, that is, it only contains POSIX permissions
+ as well as entries for the Administrators group and SYSTEM,
+ then it's kind of a POSIX-only ACL in a twisted, Windowsy
+ way. If so, we change GROUP_OBJ and CLASS_OBJ perms. */
+ if (standard_acl
+ && (idx = searchace (aclp, nentries, GROUP_OBJ)) >= 0)
+ aclp[idx].a_perm = (mode >> 3) & S_IRWXO;
if (nentries > MIN_ACL_ENTRIES
&& (idx = searchace (aclp, nentries, CLASS_OBJ)) >= 0)
aclp[idx].a_perm = (mode >> 3) & S_IRWXO;
- else if ((idx = searchace (aclp, nentries, GROUP_OBJ)) >= 0)
- aclp[idx].a_perm = (mode >> 3) & S_IRWXO;
-#endif
+
if ((idx = searchace (aclp, nentries, OTHER_OBJ)) >= 0)
aclp[idx].a_perm = mode & S_IRWXO;
if (pc.isdir ())
diff --git a/winsup/cygwin/sec_acl.cc b/winsup/cygwin/sec_acl.cc
index be54423..96c6fc3 100644
--- a/winsup/cygwin/sec_acl.cc
+++ b/winsup/cygwin/sec_acl.cc
@@ -561,11 +561,17 @@ getace (aclent_t &acl, int type, int id, DWORD
win_ace_mask,
/* From the SECURITY_DESCRIPTOR given in psd, compute user, owner, posix
attributes, as well as the POSIX acl. The function returns the number
- of entries returned in aclbufp, or -1 in case of error. */
+ of entries returned in aclbufp, or -1 in case of error.
+
+ When called from chmod, it also returns the fact if the ACL is a "standard"
+ ACL. A "standard" ACL is an ACL which only consists of ACEs for owner,
+ group, other, as well as (this is Windows) the Administrators group and
+ SYSTEM. See fhandler_disk_file::fchmod for how this is used to fake
+ stock POSIX perms even if Administrators and SYSTEM is in the ACE. */
int
get_posix_access (PSECURITY_DESCRIPTOR psd,
mode_t *attr_ret, uid_t *uid_ret, gid_t *gid_ret,
- aclent_t *aclbufp, int nentries)
+ aclent_t *aclbufp, int nentries, bool *std_acl)
{
tmp_pathbuf tp;
NTSTATUS status;
@@ -852,7 +858,10 @@ get_posix_access (PSECURITY_DESCRIPTOR psd,
GROUP_OBJ entry. */
if (ace_sid != well_known_system_sid
&& ace_sid != well_known_admins_sid)
- class_perm |= lacl[pos].a_perm;
+ {
+ class_perm |= lacl[pos].a_perm;
+ standard_ACEs_only = false;
+ }
}
}
/* For a newly created file, we'd like to know if we're running
@@ -861,7 +870,6 @@ get_posix_access (PSECURITY_DESCRIPTOR psd,
a standard ACL, we apply umask. That's not entirely correct,
but it's probably the best we can do. */
else if (type & (USER | GROUP)
- && just_created
&& standard_ACEs_only
&& ace_sid != well_known_system_sid
&& ace_sid != well_known_admins_sid)
@@ -1104,6 +1112,8 @@ out:
aclbufp[idx].a_perm &= S_IRWXO;
aclsort32 (pos, 0, aclbufp);
}
+ if (std_acl)
+ *std_acl = standard_ACEs_only;
return pos;
}
diff --git a/winsup/cygwin/security.h b/winsup/cygwin/security.h
index b4c7a02..0d744df 100644
--- a/winsup/cygwin/security.h
+++ b/winsup/cygwin/security.h
@@ -467,7 +467,7 @@ int searchace (struct acl *, int, int, uid_t id =
ILLEGAL_UID);
PSECURITY_DESCRIPTOR set_posix_access (mode_t, uid_t, gid_t, struct acl *, int,
security_descriptor &, bool);
int get_posix_access (PSECURITY_DESCRIPTOR, mode_t *, uid_t *, gid_t *,
- struct acl *, int);
+ struct acl *, int, bool * = NULL);
int getacl (HANDLE, path_conv &, int, struct acl *);
int setacl (HANDLE, path_conv &, int, struct acl *, bool &);
