On Fri, Feb 8, 2019 at 2:52 AM Tetsuo Handa
<penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On 2019/02/08 1:24, Casey Schaufler wrote:
> >>>> Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
> >>>> when lsm= parameter is specified.
> >>> That reduces flexibility somewhat. If I am debugging security modules
> >>> I may want to use lsm= to specify the order while using security= to
> >>> identify a specific exclusive module. I could do that using lsm= by
> >>> itself, but habits die hard.
> >> "lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
> >> have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
> >> to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).
> >>
> >> Since "security=" can't be used for selectively enable/disable more than one of
> >> SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
> >> better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.
> >
> > I added Kees to the CC list. Kees, what to you think about
> > ignoring security= if lsm= is specified? I'm ambivalent.
> >
> >
>
> To help administrators easily understand what LSM modules are possibly enabled by default (which
> have to be fetched from e.g. /boot/config-`uname -r`) and specify lsm= parameter when they need,
> I propose changes shown below.
>
> diff --git a/security/security.c b/security/security.c
> index 3147785e..051d708 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -51,8 +51,6 @@
> static __initdata const char *chosen_lsm_order;
> static __initdata const char *chosen_major_lsm;
>
> -static __initconst const char * const builtin_lsm_order = CONFIG_LSM;
> -
> /* Ordered list of LSMs to initialize. */
> static __initdata struct lsm_info **ordered_lsms;
> static __initdata struct lsm_info *exclusive;
> @@ -284,14 +282,22 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
> static void __init ordered_lsm_init(void)
> {
> struct lsm_info **lsm;
> + const char *order = CONFIG_LSM;
> + const char *origin = "builtin";
>
> ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
> GFP_KERNEL);
>
> - if (chosen_lsm_order)
> - ordered_lsm_parse(chosen_lsm_order, "cmdline");
> - else
> - ordered_lsm_parse(builtin_lsm_order, "builtin");
> + if (chosen_lsm_order) {
> + if (chosen_major_lsm) {
> + pr_info("security= is ignored because of lsm=\n");
This is intended to be the new default way to change the LSM
("lsm=..."), so I'd rather not have this appear every time. Also, it
must continue to interact with the builtin ordering, so if you wanted
this, I think better would be to do:
diff --git a/security/security.c b/security/security.c
index 3147785e20d7..e6153ed54361 100644
--- a/security/security.c
+++ b/security/security.c
@@ -288,9 +288,13 @@ static void __init ordered_lsm_init(void)
ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
GFP_KERNEL);
- if (chosen_lsm_order)
+ if (chosen_lsm_order) {
+ if (chosen_major_lsm) {
+ pr_info("security= is ignored because of lsm=\n");
+ chosen_major_lsm = NULL;
+ }
ordered_lsm_parse(chosen_lsm_order, "cmdline");
- else
+ } else
ordered_lsm_parse(builtin_lsm_order, "builtin");
for (lsm = ordered_lsms; *lsm; lsm++)
> + pr_info("Security Framework initializing: %s\n", order);
> + ordered_lsm_parse(order, origin);
>
> for (lsm = ordered_lsms; *lsm; lsm++)
> prepare_lsm(*lsm);
> @@ -333,8 +339,6 @@ int __init security_init(void)
> int i;
> struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
>
> - pr_info("Security Framework initializing\n");
> -
> for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
> i++)
> INIT_HLIST_HEAD(&list[i]);
--
Kees Cook
