Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 24/38] userns: Dont allow unprivileged creation of gid mappings | Date | Tue, 6 Jan 2015 17:50:36 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: "Eric W. Biederman" <ebiederm@xmission.com>
commit be7c6dba2332cef0677fbabb606e279ae76652c3 upstream.
As any gid mapping will allow and must allow for backwards compatibility dropping groups don't allow any gid mappings to be established without CAP_SETGID in the parent user namespace.
For a small class of applications this change breaks userspace and removes useful functionality. This small class of applications includes tools/testing/selftests/mount/unprivilged-remount-test.c
Most of the removed functionality will be added back with the addition of a one way knob to disable setgroups. Once setgroups is disabled setting the gid_map becomes as safe as setting the uid_map.
For more common applications that set the uid_map and the gid_map with privilege this change will have no affect.
This is part of a fix for CVE-2014-8989.
Reviewed-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/user_namespace.c | 5 ----- 1 file changed, 5 deletions(-)
--- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -810,11 +810,6 @@ static bool new_idmap_permitted(const st if (uid_eq(uid, file->f_cred->fsuid)) return true; } - else if (cap_setid == CAP_SETGID) { - kgid_t gid = make_kgid(ns->parent, id); - if (gid_eq(gid, file->f_cred->fsgid)) - return true; - } } /* Allow anyone to set a mapping that doesn't require privilege */
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