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* sec_acl.cc (setacl): Fix bug which leads to ACE duplication in

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case owner SID == group SID.
	(getacl): Reverse order of SID test against group or owner sid to
	prefer owner attributes over group attributes.  Disable setting group
	permissions equivalent to owner permissions if owner == group.  Add
	comment to explain why.  Fix indentation.
	* security.cc (get_attribute_from_acl): Change type of local variables
	containing permission to mode_t.  Apply deny mask to group if group SID
	== owner SID to avoid Everyone permissions to spill over into group
	permissions.  Disable setting group permissions equivalent to owner
	permissions if owner == group.  Add comment to explain why.
	* uinfo.cc (pwdgrp::fetch_account_from_windows): Allow user SID as
	group account if user is a "Microsoft Account".  Explain why.  Drop
	workaround enforcing primary group "Users" for "Microsoft Accounts".
This commit is contained in:
Corinna Vinschen
2015-02-27 12:59:09 +00:00
parent d2f9dbb3ee
commit 06371539bd
4 changed files with 93 additions and 52 deletions
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23
winsup/cygwin/security.cc
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@ -239,9 +239,9 @@ get_attribute_from_acl (mode_t *attribute, PACL acl, PSID owner_sid,
PSID group_sid, bool grp_member)
{
ACCESS_ALLOWED_ACE *ace;
int allow = 0;
int deny = 0;
int *flags, *anti;
mode_t allow = 0;
mode_t deny = 0;
mode_t *flags, *anti;
for (DWORD i = 0; i < acl->AceCount; ++i)
{
@ -301,6 +301,17 @@ get_attribute_from_acl (mode_t *attribute, PACL acl, PSID owner_sid,
*flags |= ((!(*anti & S_IWUSR)) ? S_IWUSR : 0);
if (ace->Mask & FILE_EXEC_BITS)
*flags |= ((!(*anti & S_IXUSR)) ? S_IXUSR : 0);
/* Apply deny mask to group if group SID == owner SID. */
if (group_sid && RtlEqualSid (owner_sid, group_sid)
&& ace->Header.AceType == ACCESS_DENIED_ACE_TYPE)
{
if (ace->Mask & FILE_READ_BITS)
*flags |= ((!(*anti & S_IRUSR)) ? S_IRGRP : 0);
if (ace->Mask & FILE_WRITE_BITS)
*flags |= ((!(*anti & S_IWUSR)) ? S_IWGRP : 0);
if (ace->Mask & FILE_EXEC_BITS)
*flags |= ((!(*anti & S_IXUSR)) ? S_IXGRP : 0);
}
}
else if (ace_sid == group_sid)
{
@ -331,6 +342,11 @@ get_attribute_from_acl (mode_t *attribute, PACL acl, PSID owner_sid,
}
}
*attribute &= ~(S_IRWXU | S_IRWXG | S_IRWXO | S_ISVTX | S_ISGID | S_ISUID);
#if 0
/* Disable owner/group permissions equivalence if owner SID == group SID.
It's technically not quite correct, but it helps in case a security
conscious application checks if a file has too open permissions. In
fact, since owner == group, there's no security issue here. */
if (owner_sid && group_sid && RtlEqualSid (owner_sid, group_sid)
/* FIXME: temporary exception for /var/empty */
&& well_known_system_sid != group_sid)
@ -340,6 +356,7 @@ get_attribute_from_acl (mode_t *attribute, PACL acl, PSID owner_sid,
| ((allow & S_IWUSR) ? S_IWGRP : 0)
| ((allow & S_IXUSR) ? S_IXGRP : 0));
}
#endif
*attribute |= allow;
}