From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: [CFT][PATCH 8/8] userns: Allow setting gid_maps without privilege when setgroups is disabled Date: Tue, 09 Dec 2014 14:43:17 -0600 Message-ID: <87a92wk10a.fsf_-_@x220.int.ebiederm.org> References: <52e0643bd47b1e5c65921d6e00aea1f724bb510a.1417281801.git.luto@amacapital.net> <87h9xez20g.fsf@x220.int.ebiederm.org> <87mw75ygwp.fsf@x220.int.ebiederm.org> <87fvcxyf28.fsf_-_@x220.int.ebiederm.org> <874mtdyexp.fsf_-_@x220.int.ebiederm.org> <87a935u3nj.fsf@x220.int.ebiederm.org> <87388xodlj.fsf@x220.int.ebiederm.org> <87h9x5re41.fsf_-_@x220.int.ebiederm.org> <87mw6xpzb0.fsf_-_@x220.int.ebiederm.org> <87ppbtn4mv.fsf@x220.int.ebiederm.org> <87a92xn2io.fsf@x220.int.ebiederm.org> <87r3w8liw4.fsf@x220.int.ebiederm.org> <87iohklfvj.fsf_-_@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87iohklfvj.fsf_-_-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org> (Eric W. Biederman's message of "Tue, 09 Dec 2014 14:36:48 -0600") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Andy Lutomirski Cc: linux-man , Kees Cook , Linux API , Linux Containers , Josh Triplett , stable , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Kenton Varda , LSM , Michael Kerrisk-manpages , Richard Weinberger , Casey Schaufler , Andrew Morton List-Id: linux-api@vger.kernel.org Now that setgroups can be disabled and not reenabled, setting gid_map without privielge can now be enabled when setgroups is disabled. This restores most of the functionality that was lost when unprivileged setting of gid_map was removed. Applications that use this functionality will need to check to see if they use setgroups or init_groups, and if they don't they can be fixed by simply disabling setgroups before writing to gid_map. Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Reviewed-by: Andy Lutomirski Signed-off-by: "Eric W. Biederman" --- kernel/user_namespace.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index b507f9af7ff2..3b29b9a52332 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -826,6 +826,11 @@ static bool new_idmap_permitted(const struct file *file, kuid_t uid = make_kuid(ns->parent, id); if (uid_eq(uid, cred->euid)) return true; + } else if (cap_setid == CAP_SETGID) { + kgid_t gid = make_kgid(ns->parent, id); + if (!(ns->flags & USERNS_SETGROUPS_ALLOWED) && + gid_eq(gid, cred->egid)) + return true; } } -- 1.9.1