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authorJames Morris <jmorris@namei.org>2017-02-15 00:17:24 +1100
committerJames Morris <james.l.morris@oracle.com>2017-03-06 11:00:12 +1100
commitdd0859dccbe291cf8179a96390f5c0e45cb9af1d (patch)
treee7a2b67dfdb2beaa07d42a314eb142289599d381
parent84e6885e9e6a818d1ca1eabb9b720b357ab07a8b (diff)
security: introduce CONFIG_SECURITY_WRITABLE_HOOKS
Subsequent patches will add RO hardening to LSM hooks, however, SELinux still needs to be able to perform runtime disablement after init to handle architectures where init-time disablement via boot parameters is not feasible. Introduce a new kernel configuration parameter CONFIG_SECURITY_WRITABLE_HOOKS, and a helper macro __lsm_ro_after_init, to handle this case. Signed-off-by: James Morris <james.l.morris@oracle.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Kees Cook <keescook@chromium.org>
-rw-r--r--include/linux/lsm_hooks.h7
-rw-r--r--security/Kconfig5
-rw-r--r--security/selinux/Kconfig6
3 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index ba3049f..1aa6333 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1920,6 +1920,13 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
}
#endif /* CONFIG_SECURITY_SELINUX_DISABLE */
+/* Currently required to handle SELinux runtime hook disable. */
+#ifdef CONFIG_SECURITY_WRITABLE_HOOKS
+#define __lsm_ro_after_init
+#else
+#define __lsm_ro_after_init __ro_after_init
+#endif /* CONFIG_SECURITY_WRITABLE_HOOKS */
+
extern int __init security_module_enable(const char *module);
extern void __init capability_add_hooks(void);
#ifdef CONFIG_SECURITY_YAMA
diff --git a/security/Kconfig b/security/Kconfig
index d900f47..3ff1bf9 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -31,6 +31,11 @@ config SECURITY
If you are unsure how to answer this question, answer N.
+config SECURITY_WRITABLE_HOOKS
+ depends on SECURITY
+ bool
+ default n
+
config SECURITYFS
bool "Enable the securityfs filesystem"
help
diff --git a/security/selinux/Kconfig b/security/selinux/Kconfig
index ea7e3ef..8af7a69 100644
--- a/security/selinux/Kconfig
+++ b/security/selinux/Kconfig
@@ -40,6 +40,7 @@ config SECURITY_SELINUX_BOOTPARAM_VALUE
config SECURITY_SELINUX_DISABLE
bool "NSA SELinux runtime disable"
depends on SECURITY_SELINUX
+ select SECURITY_WRITABLE_HOOKS
default n
help
This option enables writing to a selinuxfs node 'disable', which
@@ -50,6 +51,11 @@ config SECURITY_SELINUX_DISABLE
portability across platforms where boot parameters are difficult
to employ.
+ NOTE: selecting this option will disable the '__ro_after_init'
+ kernel hardening feature for security hooks. Please consider
+ using the selinux=0 boot parameter instead of enabling this
+ option.
+
If you are unsure how to answer this question, answer N.
config SECURITY_SELINUX_DEVELOP