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Cygwin: uinfo: don't special case current user 

fetch_account_from_windows shortcuts the current user in that
it takes the user's domain SID and just adds the matching RID
from the token's primary group to create a group SID.

How wrong this is can be very simply reproduced:

Assuming you run a native process, like cmd, with primary group
set to the Administrators builtin group.  Run Cygwin's id(1) as
child process.  id(1) will print a non-existent group as primary
group and also add it to the group list.

This can only be avoided by not special casing the current user
and thus not creating a group SID from partial information.

Fixes: 6cc7c925ce ("(pwdgrp::fetch_account_from_windows): Default primary group for the
current user to primary group from user token.")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2022-12-02 16:49:47 +01:00
parent dc7b67316d
commit a5bcfe616c
1 changed files with 6 additions and 18 deletions
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24
winsup/cygwin/uinfo.cc
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@ -1855,7 +1855,6 @@ pwdgrp::fetch_account_from_windows (fetch_user_arg_t &arg, cyg_ldap *pldap)
gid_t gid = ILLEGAL_GID; gid_t gid = ILLEGAL_GID;
bool is_domain_account = true; bool is_domain_account = true;
PCWSTR domain = NULL; PCWSTR domain = NULL;
bool is_current_user = false;
char *shell = NULL; char *shell = NULL;
char *home = NULL; char *home = NULL;
char *gecos = NULL; char *gecos = NULL;
@ -2314,18 +2313,9 @@ pwdgrp::fetch_account_from_windows (fetch_user_arg_t &arg, cyg_ldap *pldap)
uid = posix_offset + sid_sub_auth_rid (sid); uid = posix_offset + sid_sub_auth_rid (sid);
if (!is_group () && acc_type == SidTypeUser) if (!is_group () && acc_type == SidTypeUser)
{ {
/* Default primary group. If the sid is the current user, fetch /* Default primary group. Make the educated guess that the user
the default group from the current user token, otherwise make is in group "Domain Users" or "None". */
the educated guess that the user is in group "Domain Users" gid = posix_offset + DOMAIN_GROUP_RID_USERS;
or "None". */
if (sid == cygheap->user.sid ())
{
is_current_user = true;
gid = posix_offset
+ sid_sub_auth_rid (cygheap->user.groups.pgsid);
}
else
gid = posix_offset + DOMAIN_GROUP_RID_USERS;
} }
if (is_domain_account) if (is_domain_account)
@ -2336,11 +2326,9 @@ pwdgrp::fetch_account_from_windows (fetch_user_arg_t &arg, cyg_ldap *pldap)
/* On AD machines, use LDAP to fetch domain account infos. */ /* On AD machines, use LDAP to fetch domain account infos. */
if (cygheap->dom.primary_dns_name ()) if (cygheap->dom.primary_dns_name ())
{ {
/* For the current user we got correctly cased username and /* Fetch primary group from AD and overwrite the one we
the primary group via process token. For any other user just guessed above. */
we fetch it from AD and overwrite it. */ if (cldap->fetch_ad_account (sid, false, domain))
if (!is_current_user
&& cldap->fetch_ad_account (sid, false, domain))
{ {
if ((val = cldap->get_account_name ())) if ((val = cldap->get_account_name ()))
wcscpy (name, val); wcscpy (name, val);