From 40852275a94afb3e836be9248399e036982d1a79 Mon Sep 17 00:00:00 2001 From: Micah Morton Date: Tue, 22 Jan 2019 14:42:09 -0800 Subject: LSM: add SafeSetID module that gates setid calls This change ensures that the set*uid family of syscalls in kernel/sys.c (setreuid, setuid, setresuid, setfsuid) all call ns_capable_common with the CAP_OPT_INSETID flag, so capability checks in the security_capable hook can know whether they are being called from within a set*uid syscall. This change is a no-op by itself, but is needed for the proposed SafeSetID LSM. Signed-off-by: Micah Morton Acked-by: Kees Cook Signed-off-by: James Morris --- kernel/capability.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'kernel/capability.c') diff --git a/kernel/capability.c b/kernel/capability.c index cfbbcb68e11e..1444f3954d75 100644 --- a/kernel/capability.c +++ b/kernel/capability.c @@ -415,6 +415,25 @@ bool ns_capable_noaudit(struct user_namespace *ns, int cap) } EXPORT_SYMBOL(ns_capable_noaudit); +/** + * ns_capable_setid - Determine if the current task has a superior capability + * in effect, while signalling that this check is being done from within a + * setid syscall. + * @ns: The usernamespace we want the capability in + * @cap: The capability to be tested for + * + * Return true if the current task has the given superior capability currently + * available for use, false if not. + * + * This sets PF_SUPERPRIV on the task if the capability is available on the + * assumption that it's about to be used. + */ +bool ns_capable_setid(struct user_namespace *ns, int cap) +{ + return ns_capable_common(ns, cap, CAP_OPT_INSETID); +} +EXPORT_SYMBOL(ns_capable_setid); + /** * capable - Determine if the current task has a superior capability in effect * @cap: The capability to be tested for -- cgit v1.2.3