[PATCH security-next v3 29/29] LSM: Add all exclusive LSMs to ordered initialization

From: Kees Cook
Date: Mon Sep 24 2018 - 20:19:29 EST


This removes CONFIG_DEFAULT_SECURITY in favor of the explicit build-time
ordering offered by CONFIG_LSM_ORDER, and adds all the exclusive LSMs to
the ordered LSM initialization. The old meaning of CONFIG_DEFAULT_SECURITY
is now captured by which exclusive LSM is listed first in the LSM order.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
security/Kconfig | 43 ++++---------------------------------------
security/security.c | 23 +----------------------
2 files changed, 5 insertions(+), 61 deletions(-)

diff --git a/security/Kconfig b/security/Kconfig
index e37de9a44747..efa4826c3d99 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -239,43 +239,6 @@ source security/yama/Kconfig

source security/integrity/Kconfig

-choice
- prompt "Default security module"
- default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
- default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
- default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
- default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
- default DEFAULT_SECURITY_DAC
-
- help
- Select the security module that will be used by default if the
- kernel parameter security= is not specified.
-
- config DEFAULT_SECURITY_SELINUX
- bool "SELinux" if SECURITY_SELINUX=y
-
- config DEFAULT_SECURITY_SMACK
- bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
-
- config DEFAULT_SECURITY_TOMOYO
- bool "TOMOYO" if SECURITY_TOMOYO=y
-
- config DEFAULT_SECURITY_APPARMOR
- bool "AppArmor" if SECURITY_APPARMOR=y
-
- config DEFAULT_SECURITY_DAC
- bool "Unix Discretionary Access Controls"
-
-endchoice
-
-config DEFAULT_SECURITY
- string
- default "selinux" if DEFAULT_SECURITY_SELINUX
- default "smack" if DEFAULT_SECURITY_SMACK
- default "tomoyo" if DEFAULT_SECURITY_TOMOYO
- default "apparmor" if DEFAULT_SECURITY_APPARMOR
- default "" if DEFAULT_SECURITY_DAC
-
config LSM_ENABLE
string "LSMs to enable at boot time"
default "all"
@@ -293,12 +256,14 @@ config LSM_ENABLE

config LSM_ORDER
string "Default initialization order of builtin LSMs"
- default "yama,loadpin,integrity"
+ default "yama,loadpin,integrity,selinux,smack,tomoyo,apparmor"
help
A comma-separated list of LSMs, in initialization order.
Any LSMs left off this list will be link-order initialized
after any listed LSMs. Any LSMs listed here but not built in
- the kernel will be ignored.
+ the kernel will be ignored. If the boot parameter
+ "lsm.order=" is used, it will override this order, with any
+ unlisted LSMs falling back to the order of this config, etc.

If unsure, leave this as the default.

diff --git a/security/security.c b/security/security.c
index 5a3e19f1fe48..fedc26fb8554 100644
--- a/security/security.c
+++ b/security/security.c
@@ -154,7 +154,6 @@ static void __init parse_lsm_order(const char *order, const char *origin)

for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
if (lsm->order == LSM_ORDER_MUTABLE &&
- (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 &&
strcmp(lsm->name, name) == 0) {
append_ordered_lsm(lsm, origin);
found = true;
@@ -186,8 +185,7 @@ static void __init prepare_lsm_order(void)

/* Add any missing LSMs, in link order. */
for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
- if (lsm->order == LSM_ORDER_MUTABLE &&
- (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
+ if (lsm->order == LSM_ORDER_MUTABLE)
append_ordered_lsm(lsm, "link-time");
}

@@ -245,18 +243,6 @@ static void __init ordered_lsm_init(void)
maybe_initialize_lsm(*lsm);
}

-static void __init major_lsm_init(void)
-{
- struct lsm_info *lsm;
-
- for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
- if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
- continue;
-
- maybe_initialize_lsm(lsm);
- }
-}
-
static void __init parse_lsm_enable(const char *str,
void (*set)(struct lsm_info *, bool),
bool enabled)
@@ -290,8 +276,6 @@ static void __init prepare_lsm_enable(void)
parse_lsm_enable(chosen_lsm_disable, set_enabled, false);

/* Process "security=", if given. */
- if (!chosen_major_lsm)
- chosen_major_lsm = CONFIG_DEFAULT_SECURITY;
if (chosen_major_lsm) {
struct lsm_info *lsm;

@@ -334,11 +318,6 @@ int __init security_init(void)
prepare_lsm_order();
ordered_lsm_init();

- /*
- * Load all the remaining security modules.
- */
- major_lsm_init();
-
kfree(ordered_lsms);
return 0;
}
--
2.17.1