Merge tag 'blob-stacking-security-next' of https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into next-general

LSM: Module stacking for SARA and Landlock

The combined series of LSM refactoring and addition of blob-sharing for
SARA and Landlock.

From Casey:

v5: Include Kees Cook's rework of the lsm command
    line interface.
v4: Finer granularity in the patches and other
    cleanups suggested by Kees Cook.
    Removed dead code created by the removal of SELinux
    credential blob poisoning.
v3: Add ipc blob for SARA and task blob for Landlock.
    Removing the SELinux cred blob pointer poisoning
    results selinux_is_enabled() being unused, so it and
    all it's overhead has been removed.
    Broke up the cred infrastructure patch.
v2: Reduce the patchset to what is required to support
    the proposed SARA and LandLock security modules

The SARA security module is intended to be used
in conjunction with other security modules. It requires
state to be maintained for the credential, which
in turn requires a mechanism for sharing the credential
security blob. It also uses the ipc security blob. The
module also requires mechanism for user space manipulation
of the credential information, hence an additional
subdirectory in /proc/.../attr.

The LandLock security module provides user configurable
policy in the secmark mechanism. It requires data in
the credential, file, inode and task security blobs. For
this to be used along side the existing "major" security
modules mechanism for sharing these blobs are provided.

A side effect of providing sharing of the crendential
security blob is that the TOMOYO module can be used at
the same time as the other "major" modules.

The mechanism for configuring which security modules are
enabled has to change when stacking in enabled. Any
module that uses just the security blobs that are shared
can be selected. Additionally, one other "major" module
can be selected.

The security module stacking issues around networking and
IPC are not addressed here as they are beyond what is
required for TOMOYO, SARA and LandLock.

2 files changed, 34 insertions, 7 deletions

diff --git a/security/selinux/include/audit.h b/security/selinux/include/audit.h
index 1bdf973433cc..36e1d44c0209 100644
--- a/security/selinux/include/audit.h
+++ b/security/selinux/include/audit.h
@@ -1,9 +1,6 @@
 /*
  * SELinux support for the Audit LSM hooks
  *
- * Most of below header was moved from include/linux/selinux.h which
- * is released under below copyrights:
- *
  * Author: James Morris <jmorris@redhat.com>
  *
  * Copyright (C) 2005 Red Hat, Inc., James Morris <jmorris@redhat.com>
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index cc5e26b0161b..231262d8eac9 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -25,6 +25,8 @@
 #include <linux/binfmts.h>
 #include <linux/in.h>
 #include <linux/spinlock.h>
+#include <linux/lsm_hooks.h>
+#include <linux/msg.h>
 #include <net/net_namespace.h>
 #include "flask.h"
 #include "avc.h"
@@ -56,10 +58,7 @@ enum label_initialized {
 
 struct inode_security_struct {
 	struct inode *inode;	/* back pointer to inode object */
-	union {
-		struct list_head list;	/* list of inode_security_struct */
-		struct rcu_head rcu;	/* for freeing the inode_security_struct */
-	};
+	struct list_head list;	/* list of inode_security_struct */
 	u32 task_sid;		/* SID of creating task */
 	u32 sid;		/* SID of this object */
 	u16 sclass;		/* security class of this object */
@@ -158,4 +157,35 @@ struct bpf_security_struct {
 	u32 sid;  /*SID of bpf obj creater*/
 };
 
+extern struct lsm_blob_sizes selinux_blob_sizes;
+static inline struct task_security_struct *selinux_cred(const struct cred *cred)
+{
+	return cred->security + selinux_blob_sizes.lbs_cred;
+}
+
+static inline struct file_security_struct *selinux_file(const struct file *file)
+{
+	return file->f_security + selinux_blob_sizes.lbs_file;
+}
+
+static inline struct inode_security_struct *selinux_inode(
+						const struct inode *inode)
+{
+	if (unlikely(!inode->i_security))
+		return NULL;
+	return inode->i_security + selinux_blob_sizes.lbs_inode;
+}
+
+static inline struct msg_security_struct *selinux_msg_msg(
+						const struct msg_msg *msg_msg)
+{
+	return msg_msg->security + selinux_blob_sizes.lbs_msg_msg;
+}
+
+static inline struct ipc_security_struct *selinux_ipc(
+						const struct kern_ipc_perm *ipc)
+{
+	return ipc->security + selinux_blob_sizes.lbs_ipc;
+}
+
 #endif /* _SELINUX_OBJSEC_H_ */