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Date: Tue, 6 Jan 2015 17:50:03 -0800 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Andy Lutomirski <luto@...capital.net>, "Eric W. Biederman" <ebiederm@...ssion.com> Subject: [PATCH 3.18 60/84] userns: Dont allow unprivileged creation of gid mappings 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" <ebiederm@...ssion.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@...capital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- kernel/user_namespace.c | 4 ---- 1 file changed, 4 deletions(-) --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -821,10 +821,6 @@ static bool new_idmap_permitted(const st kuid_t uid = make_kuid(ns->parent, id); 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; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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