Define a new LSM hook security_lsm_manage_policy and wire it into the
lsm_manage_policy() syscall so that LSMs can register a unified interface
for policy management. This initial, minimal implementation only supports
the LSM_POLICY_LOAD operation to limit changes.
Signed-off-by: Maxime Bélair <maxime.belair@xxxxxxxxxxxxx>
---
include/linux/lsm_hook_defs.h | 2 ++
include/linux/security.h | 7 +++++++
include/uapi/linux/lsm.h | 8 ++++++++
security/lsm_syscalls.c | 7 ++++++-
security/security.c | 21 +++++++++++++++++++++
5 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index bf3bbac4e02a..04b6e34d5111 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -464,3 +464,5 @@ LSM_HOOK(int, 0, bdev_alloc_security, struct block_device *bdev)
LSM_HOOK(void, LSM_RET_VOID, bdev_free_security, struct block_device *bdev)
LSM_HOOK(int, 0, bdev_setintegrity, struct block_device *bdev,
enum lsm_integrity_type type, const void *value, size_t size)
+LSM_HOOK(int, 0, lsm_manage_policy, u32 lsm_id, u32 op, void __user *buf,
+ size_t size, u32 flags)
diff --git a/include/linux/security.h b/include/linux/security.h
index cc9b54d95d22..dab547ee691c 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -581,6 +581,8 @@ void security_bdev_free(struct block_device *bdev);
int security_bdev_setintegrity(struct block_device *bdev,
enum lsm_integrity_type type, const void *value,
size_t size);
+int security_lsm_manage_policy(u32 lsm_id, u32 op, void __user *buf,
+ size_t size, u32 flags);
#else /* CONFIG_SECURITY */
/**
@@ -1602,6 +1604,11 @@ static inline int security_bdev_setintegrity(struct block_device *bdev,
{
return 0;
}
+static int security_lsm_manage_policy(u32 lsm_id, u32 op, void __user *buf,
+ size_t size, u32 flags)
+
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_SECURITY */
diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
index 938593dfd5da..7335f9723114 100644
--- a/include/uapi/linux/lsm.h
+++ b/include/uapi/linux/lsm.h
@@ -90,4 +90,12 @@ struct lsm_ctx {
*/
#define LSM_FLAG_SINGLE 0x0001
+/*
+ * LSM_POLICY_XXX definition identifies operation to manage lsm
+ * policies
+ */
+
+#define LSM_POLICY_UNDEF 0
+#define LSM_POLICY_LOAD 100
+
#endif /* _UAPI_LINUX_LSM_H */
diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
index dcaad8818679..b39e6635a7d5 100644
--- a/security/lsm_syscalls.c
+++ b/security/lsm_syscalls.c
@@ -122,5 +122,10 @@ SYSCALL_DEFINE3(lsm_list_modules, u64 __user *, ids, u32 __user *, size,
SYSCALL_DEFINE5(lsm_manage_policy, u32, lsm_id, u32, op, void __user *, buf, u32
__user *, size, u32, flags)
{
- return 0;
+ size_t usize;
+
+ if (get_user(usize, size))
+ return -EFAULT;
+
+ return security_lsm_manage_policy(lsm_id, op, buf, usize, flags);
}
diff --git a/security/security.c b/security/security.c
index fb57e8fddd91..256104e338b1 100644
--- a/security/security.c
+++ b/security/security.c
@@ -5883,6 +5883,27 @@ int security_bdev_setintegrity(struct block_device *bdev,
}
EXPORT_SYMBOL(security_bdev_setintegrity);
+/**
+ * security_lsm_manage_policy() - Manage the policies of LSMs
+ * @lsm_id: id of the lsm to target
+ * @op: Operation to perform (one of the LSM_POLICY_XXX values)
+ * @buf: userspace pointer to policy data
+ * @size: size of @buf
+ * @flags: lsm policy management flags
+ *
+ * Manage the policies of a LSM. This notably allows to update them even when
+ * the lsmfs is unavailable is restricted. Currently, only LSM_POLICY_LOAD is
+ * supported.
+ *
+ * Return: Returns 0 on success, error on failure.
+ */
+int security_lsm_manage_policy(u32 lsm_id, u32 op, void __user *buf,
+ size_t size, u32 flags)
+{
+ return call_int_hook(lsm_manage_policy, lsm_id, op, buf, size, flags);
+}
+EXPORT_SYMBOL(security_lsm_manage_policy);
+
#ifdef CONFIG_PERF_EVENTS
/**
* security_perf_event_open() - Check if a perf event open is allowed
--
2.48.1
