In order to both support old "security=" Legacy Major LSM selection, and
handling real exclusivity, this creates LSM_FLAG_EXCLUSIVE and updates
the selection logic to handle them.
Signed-off-by: Kees Cook <keesc...@chromium.org>
Reviewed-by: Casey Schaufler <ca...@schaufler-ca.com>
---
include/linux/lsm_hooks.h | 1 +
security/apparmor/lsm.c | 2 +-
security/security.c | 12 ++++++++++++
security/selinux/hooks.c | 2 +-
security/smack/smack_lsm.c | 2 +-
security/tomoyo/tomoyo.c | 2 +-
6 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 36e7a716fdfe..2c9cf89a20ad 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2040,6 +2040,7 @@ extern void security_add_hooks(struct security_hook_list
*hooks, int count,
char *lsm);
#define LSM_FLAG_LEGACY_MAJOR BIT(0)
+#define LSM_FLAG_EXCLUSIVE BIT(1)
enum lsm_order {
LSM_ORDER_FIRST = -1, /* This is only for capabilities. */
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 4cd96a66ed6f..4eb74a6f2020 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1599,7 +1599,7 @@ static int __init apparmor_init(void)
DEFINE_LSM(apparmor) = {
.name = "apparmor",
- .flags = LSM_FLAG_LEGACY_MAJOR,
+ .flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
.enabled = &apparmor_enabled,
.init = apparmor_init,
};
diff --git a/security/security.c b/security/security.c
index 813dab3b5b97..7d542e78b7e8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -52,6 +52,7 @@ static __initconst const char * const builtin_lsm_order =
CONFIG_LSM_ORDER;
/* Ordered list of LSMs to initialize. */
static __initdata struct lsm_info **ordered_lsms;
+static __initdata struct lsm_info *exclusive;
static __initdata bool debug;
#define init_debug(...) \
@@ -196,6 +197,12 @@ static bool __init lsm_allowed(struct lsm_info *lsm)
if (!is_enabled(lsm))
return false;
+ /* Not allowed if another exclusive LSM already initialized. */
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && exclusive) {
+ init_debug("exclusive disabled: %s\n", lsm->name);
+ return false;
+ }
+
return true;
}
@@ -211,6 +218,11 @@ static void __init maybe_initialize_lsm(struct lsm_info
*lsm)
if (enabled) {
int ret;
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
+ exclusive = lsm;
+ init_debug("exclusive: %s\n", lsm->name);
+ }
+
init_debug("initializing %s\n", lsm->name);
ret = lsm->init();
WARN(ret, "%s failed to initialize: %d\n", lsm->name, ret);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 8f5eea097612..c070d3761ddc 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7181,7 +7181,7 @@ void selinux_complete_init(void)
all processes and objects when they are created. */
DEFINE_LSM(selinux) = {
.name = "selinux",
- .flags = LSM_FLAG_LEGACY_MAJOR,
+ .flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
.enabled = &selinux_enabled,
.init = selinux_init,
};
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index f243044d5a55..92e4baa342f8 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4881,6 +4881,6 @@ static __init int smack_init(void)
*/
DEFINE_LSM(smack) = {
.name = "smack",
- .flags = LSM_FLAG_LEGACY_MAJOR,
+ .flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
.init = smack_init,
};
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index a46f6bc1e97c..daff7d7897ad 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -550,6 +550,6 @@ static int __init tomoyo_init(void)
DEFINE_LSM(tomoyo) = {
.name = "tomoyo",
- .flags = LSM_FLAG_LEGACY_MAJOR,
+ .flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
.init = tomoyo_init,
};
--
2.17.1
