[PATCH 08/58] LSM: Use lsm_export in the kernel_ask_as hooks

[Casey Schaufler]

Convert the kernel_ask_as hooks to use the lsm_export
structure instead of a u32 secid. There is some scaffolding
involved that will be removed when security_kernel_ask_as()
is updated.

Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
---
 include/linux/lsm_hooks.h  |  4 ++--
 security/security.c        | 15 ++++++++++++++-
 security/selinux/hooks.c   | 17 ++++++++++++++---
 security/smack/smack_lsm.c | 12 +++++++++++-
 4 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 62783a923136..800040050032 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -578,7 +578,7 @@
  * @kernel_act_as:
  *	Set the credentials for a kernel service to act as (subjective context).
  *	@new points to the credentials to be modified.
- *	@secid specifies the security ID to be set
+ *	@l specifies the security data to be set
  *	The current task must be the one that nominated @secid.
  *	Return 0 if successful.
  * @kernel_create_files_as:
@@ -1598,7 +1598,7 @@ union security_list_options {
 				gfp_t gfp);
 	void (*cred_transfer)(struct cred *new, const struct cred *old);
 	void (*cred_getsecid)(const struct cred *c, struct lsm_export *l);
-	int (*kernel_act_as)(struct cred *new, u32 secid);
+	int (*kernel_act_as)(struct cred *new, struct lsm_export *l);
 	int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
 	int (*kernel_module_request)(char *kmod_name);
 	int (*kernel_load_data)(enum kernel_load_data_id id);
diff --git a/security/security.c b/security/security.c
index 802557ff6f60..3a766755b722 100644
--- a/security/security.c
+++ b/security/security.c
@@ -742,6 +742,15 @@ static inline void lsm_export_secid(struct lsm_export *data, u32 *secid)
 	}
 }
 
+static inline void lsm_export_to_all(struct lsm_export *data, u32 secid)
+{
+	data->selinux = secid;
+	data->smack = secid;
+	data->apparmor = secid;
+	data->flags = LSM_EXPORT_SELINUX | LSM_EXPORT_SMACK |
+		      LSM_EXPORT_APPARMOR;
+}
+
 /* Security operations */
 
 int security_binder_set_context_mgr(struct task_struct *mgr)
@@ -1647,7 +1656,11 @@ EXPORT_SYMBOL(security_cred_getsecid);
 
 int security_kernel_act_as(struct cred *new, u32 secid)
 {
-	return call_int_hook(kernel_act_as, 0, new, secid);
+	struct lsm_export data = { .flags = LSM_EXPORT_NONE };
+
+	lsm_export_to_all(&data, secid);
+
+	return call_int_hook(kernel_act_as, 0, new, &data);
 }
 
 int security_kernel_create_files_as(struct cred *new, struct inode *inode)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c82108793fb5..b88a51b6ca41 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -222,6 +222,14 @@ static inline void selinux_export_secid(struct lsm_export *l, u32 secid)
 	l->flags |= LSM_EXPORT_SELINUX;
 }
 
+static inline void selinux_import_secid(struct lsm_export *l, u32 *secid)
+{
+	if (l->flags & LSM_EXPORT_SELINUX)
+		*secid = l->selinux;
+	else
+		*secid = SECSID_NULL;
+}
+
 /*
  * get the security ID of a set of credentials
  */
@@ -3773,19 +3781,22 @@ static void selinux_cred_getsecid(const struct cred *c, struct lsm_export *l)
  * set the security data for a kernel service
  * - all the creation contexts are set to unlabelled
  */
-static int selinux_kernel_act_as(struct cred *new, u32 secid)
+static int selinux_kernel_act_as(struct cred *new, struct lsm_export *l)
 {
 	struct task_security_struct *tsec = selinux_cred(new);
+	u32 nsid;
 	u32 sid = current_sid();
 	int ret;
 
+	selinux_import_secid(l, &nsid);
+
 	ret = avc_has_perm(&selinux_state,
-			   sid, secid,
+			   sid, nsid,
 			   SECCLASS_KERNEL_SERVICE,
 			   KERNEL_SERVICE__USE_AS_OVERRIDE,
 			   NULL);
 	if (ret == 0) {
-		tsec->sid = secid;
+		tsec->sid = nsid;
 		tsec->create_sid = 0;
 		tsec->keycreate_sid = 0;
 		tsec->sockcreate_sid = 0;
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 13ac3045a388..3b77a0324c3d 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -475,6 +475,14 @@ static inline void smack_export_secid(struct lsm_export *l, u32 secid)
 	l->flags |= LSM_EXPORT_SMACK;
 }
 
+static inline void smack_import_secid(struct lsm_export *l, u32 *secid)
+{
+	if (l->flags & LSM_EXPORT_SMACK)
+		*secid = l->smack;
+	else
+		*secid = 0;
+}
+
 /*
  * LSM hooks.
  * We he, that is fun!
@@ -1997,10 +2005,12 @@ static void smack_cred_getsecid(const struct cred *cred, struct lsm_export *l)
  *
  * Set the security data for a kernel service.
  */
-static int smack_kernel_act_as(struct cred *new, u32 secid)
+static int smack_kernel_act_as(struct cred *new, struct lsm_export *l)
 {
+	u32 secid;
 	struct task_smack *new_tsp = smack_cred(new);
 
+	smack_import_secid(l, &secid);
 	new_tsp->smk_task = smack_from_secid(secid);
 	return 0;
 }
-- 
2.19.1