https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=dc7b67316d01c77d81ad6561869b9b89527c2ac8
commit dc7b67316d01c77d81ad6561869b9b89527c2ac8 Author: Corinna Vinschen <[email protected]> AuthorDate: Fri Dec 2 16:37:33 2022 +0100 Commit: Corinna Vinschen <[email protected]> CommitDate: Fri Dec 2 16:37:33 2022 +0100 Cygwin: uinfo: prefer token primary group internal_getlogin overwrites the process token primary group if it differs from the primary group as stored in the passwd DB. However, this also overwrites the primary group of the process if it has been deliberately changed by a former process (e. g., newgrp), and the current process has a non-Cygwin process as parent. Our docs claim we restrict overwriting the primary group to local, non-domain user accounts anyway, and it was actually meant this way. So check for exactly that before overwriting the primary group in the token: It's only allowed if the user is a local account and the primary group in the token is still the default group "None". Fixes: 6cc7c925ce861 ("(internal_getlogin): Give primary group from user token more weight.") Signed-off-by: Corinna Vinschen <[email protected]> Diff: --- winsup/cygwin/uinfo.cc | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/winsup/cygwin/uinfo.cc b/winsup/cygwin/uinfo.cc index a96c5e7fc6a0..db475d710eb2 100644 --- a/winsup/cygwin/uinfo.cc +++ b/winsup/cygwin/uinfo.cc @@ -163,11 +163,20 @@ internal_getlogin (cygheap_user &user) user.set_name (pwd->pw_name); myself->uid = pwd->pw_uid; - myself->gid = pwd->pw_gid; + myself->gid = pgrp ? pgrp->gr_gid : pwd->pw_gid; + /* If the primary group in the passwd DB is different from the primary - group in the user token, we have to find the SID of that group and - try to override the token primary group. */ - if (!pgrp || myself->gid != pgrp->gr_gid) + group in the user token, and if the primary group is the default + group of a local user ("None", localized), we have to find the SID + of that group and try to override the token primary group. Also + makes sure we're not on a domain controller, where account_sid () + == primary_sid (). */ + gsid = cygheap->dom.account_sid (); + gsid.append (DOMAIN_GROUP_RID_USERS); + if (!pgrp + || (myself->gid != pgrp->gr_gid + && cygheap->dom.account_sid () != cygheap->dom.primary_sid () + && RtlEqualSid (gsid, user.groups.pgsid))) { if (gsid.getfromgr (grp = internal_getgrgid (pwd->pw_gid, &cldap))) {
