From: Matthew Garrett <matthewgarrett@google.com>
Date: Mon, 19 Aug 2019 17:17:37 -0700
Subject: security: Support early LSMs
Patch-mainline: v5.4-rc1
Git-commit: e6b1db98cf4d54d9ea59cfcc195f70dc946fdd38
References: jsc#SLE-9870
The lockdown module is intended to allow for kernels to be locked down
early in boot - sufficiently early that we don't have the ability to
kmalloc() yet. Add support for early initialisation of some LSMs, and
then add them to the list of names when we do full initialisation later.
Early LSMs are initialised in link order and cannot be overridden via
boot parameters, and cannot make use of kmalloc() (since the allocator
isn't initialised yet).
(Fixed by Stephen Rothwell to include a stub to fix builds when
!CONFIG_SECURITY)
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
include/asm-generic/vmlinux.lds.h | 8 +++++-
include/linux/lsm_hooks.h | 6 ++++
include/linux/security.h | 6 ++++
init/main.c | 1
security/security.c | 50 +++++++++++++++++++++++++++++++-------
5 files changed, 62 insertions(+), 9 deletions(-)
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -215,8 +215,13 @@
__start_lsm_info = .; \
KEEP(*(.lsm_info.init)) \
__end_lsm_info = .;
+#define EARLY_LSM_TABLE() . = ALIGN(8); \
+ __start_early_lsm_info = .; \
+ KEEP(*(.early_lsm_info.init)) \
+ __end_early_lsm_info = .;
#else
#define LSM_TABLE()
+#define EARLY_LSM_TABLE()
#endif
#define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name)
@@ -627,7 +632,8 @@
ACPI_PROBE_TABLE(timer) \
THERMAL_TABLE(governor) \
EARLYCON_TABLE() \
- LSM_TABLE()
+ LSM_TABLE() \
+ EARLY_LSM_TABLE()
#define INIT_TEXT \
*(.init.text .init.text.*) \
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2104,12 +2104,18 @@ struct lsm_info {
};
extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
+extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
#define DEFINE_LSM(lsm) \
static struct lsm_info __lsm_##lsm \
__used __section(.lsm_info.init) \
__aligned(sizeof(unsigned long))
+#define DEFINE_EARLY_LSM(lsm) \
+ static struct lsm_info __early_lsm_##lsm \
+ __used __section(.early_lsm_info.init) \
+ __aligned(sizeof(unsigned long))
+
#ifdef CONFIG_SECURITY_SELINUX_DISABLE
/*
* Assuring the safety of deleting a security module is up to
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -195,6 +195,7 @@ int unregister_blocking_lsm_notifier(str
/* prototypes */
extern int security_init(void);
+extern int early_security_init(void);
/* Security operations */
int security_binder_set_context_mgr(struct task_struct *mgr);
@@ -422,6 +423,11 @@ static inline int security_init(void)
{
return 0;
}
+
+static inline int early_security_init(void)
+{
+ return 0;
+}
static inline int security_binder_set_context_mgr(struct task_struct *mgr)
{
--- a/init/main.c
+++ b/init/main.c
@@ -593,6 +593,7 @@ asmlinkage __visible void __init start_k
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
+ early_security_init();
setup_arch(&command_line);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
--- a/security/security.c
+++ b/security/security.c
@@ -33,6 +33,7 @@
/* How many LSMs were built into the kernel? */
#define LSM_COUNT (__end_lsm_info - __start_lsm_info)
+#define EARLY_LSM_COUNT (__end_early_lsm_info - __start_early_lsm_info)
struct security_hook_heads security_hook_heads __lsm_ro_after_init;
static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);
@@ -277,6 +278,8 @@ static void __init ordered_lsm_parse(con
static void __init lsm_early_cred(struct cred *cred);
static void __init lsm_early_task(struct task_struct *task);
+static int lsm_append(const char *new, char **result);
+
static void __init ordered_lsm_init(void)
{
struct lsm_info **lsm;
@@ -323,6 +326,26 @@ static void __init ordered_lsm_init(void
kfree(ordered_lsms);
}
+int __init early_security_init(void)
+{
+ int i;
+ struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
+ struct lsm_info *lsm;
+
+ for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
+ i++)
+ INIT_HLIST_HEAD(&list[i]);
+
+ for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+ if (!lsm->enabled)
+ lsm->enabled = &lsm_enabled_true;
+ prepare_lsm(lsm);
+ initialize_lsm(lsm);
+ }
+
+ return 0;
+}
+
/**
* security_init - initializes the security framework
*
@@ -330,14 +353,18 @@ static void __init ordered_lsm_init(void
*/
int __init security_init(void)
{
- int i;
- struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
+ struct lsm_info *lsm;
pr_info("Security Framework initializing\n");
- for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
- i++)
- INIT_HLIST_HEAD(&list[i]);
+ /*
+ * Append the names of the early LSM modules now that kmalloc() is
+ * available
+ */
+ for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+ if (lsm->enabled)
+ lsm_append(lsm->name, &lsm_names);
+ }
/* Load LSMs in specified order. */
ordered_lsm_init();
@@ -384,7 +411,7 @@ static bool match_last_lsm(const char *l
return !strcmp(last, lsm);
}
-static int lsm_append(char *new, char **result)
+static int lsm_append(const char *new, char **result)
{
char *cp;
@@ -422,8 +449,15 @@ void __init security_add_hooks(struct se
hooks[i].lsm = lsm;
hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
}
- if (lsm_append(lsm, &lsm_names) < 0)
- panic("%s - Cannot get early memory.\n", __func__);
+
+ /*
+ * Don't try to append during early_security_init(), we'll come back
+ * and fix this up afterwards.
+ */
+ if (slab_is_available()) {
+ if (lsm_append(lsm, &lsm_names) < 0)
+ panic("%s - Cannot get early memory.\n", __func__);
+ }
}
int call_blocking_lsm_notifier(enum lsm_event event, void *data)