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.

4 files changed, 39 insertions, 52 deletions

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 4907c9df86b3..ddd45bb74887 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -15,7 +15,6 @@
 #include <linux/capability.h>
 #include <linux/init.h>
 #include <linux/key.h>
-#include <linux/selinux.h>
 #include <linux/atomic.h>
 #include <linux/uidgid.h>
 #include <linux/sched.h>
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 9a0bdf91e646..40511a8a5ae6 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2028,6 +2028,18 @@ struct security_hook_list {
 } __randomize_layout;
 
 /*
+ * Security blob size or offset data.
+ */
+struct lsm_blob_sizes {
+	int	lbs_cred;
+	int	lbs_file;
+	int	lbs_inode;
+	int	lbs_ipc;
+	int	lbs_msg_msg;
+	int	lbs_task;
+};
+
+/*
  * Initializing a security_hook_list structure takes
  * up a lot of space in a source file. This macro takes
  * care of the common case and reduces the amount of
@@ -2042,9 +2054,21 @@ extern char *lsm_names;
 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. */
+	LSM_ORDER_MUTABLE = 0,
+};
+
 struct lsm_info {
 	const char *name;	/* Required. */
+	enum lsm_order order;	/* Optional: default is LSM_ORDER_MUTABLE */
+	unsigned long flags;	/* Optional: flags describing LSM */
+	int *enabled;		/* Optional: controlled by CONFIG_LSM */
 	int (*init)(void);	/* Required. */
+	struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */
 };
 
 extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
@@ -2084,17 +2108,11 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
 #define __lsm_ro_after_init	__ro_after_init
 #endif /* CONFIG_SECURITY_WRITABLE_HOOKS */
 
-extern int __init security_module_enable(const char *module);
-extern void __init capability_add_hooks(void);
-#ifdef CONFIG_SECURITY_YAMA
-extern void __init yama_add_hooks(void);
-#else
-static inline void __init yama_add_hooks(void) { }
-#endif
-#ifdef CONFIG_SECURITY_LOADPIN
-void __init loadpin_add_hooks(void);
-#else
-static inline void loadpin_add_hooks(void) { };
+extern int lsm_inode_alloc(struct inode *inode);
+
+#ifdef CONFIG_SECURITY
+void __init lsm_early_cred(struct cred *cred);
+void __init lsm_early_task(struct task_struct *task);
 #endif
 
 #endif /* ! __LINUX_LSM_HOOKS_H */
diff --git a/include/linux/security.h b/include/linux/security.h
index dbfb5a66babb..b2c5333ed4b5 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -366,8 +366,10 @@ int security_sem_semctl(struct kern_ipc_perm *sma, int cmd);
 int security_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
 			unsigned nsops, int alter);
 void security_d_instantiate(struct dentry *dentry, struct inode *inode);
-int security_getprocattr(struct task_struct *p, char *name, char **value);
-int security_setprocattr(const char *name, void *value, size_t size);
+int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
+			 char **value);
+int security_setprocattr(const char *lsm, const char *name, void *value,
+			 size_t size);
 int security_netlink_send(struct sock *sk, struct sk_buff *skb);
 int security_ismaclabel(const char *name);
 int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
@@ -1112,15 +1114,18 @@ static inline int security_sem_semop(struct kern_ipc_perm *sma,
 	return 0;
 }
 
-static inline void security_d_instantiate(struct dentry *dentry, struct inode *inode)
+static inline void security_d_instantiate(struct dentry *dentry,
+					  struct inode *inode)
 { }
 
-static inline int security_getprocattr(struct task_struct *p, char *name, char **value)
+static inline int security_getprocattr(struct task_struct *p, const char *lsm,
+				       char *name, char **value)
 {
 	return -EINVAL;
 }
 
-static inline int security_setprocattr(char *name, void *value, size_t size)
+static inline int security_setprocattr(const char *lsm, char *name,
+				       void *value, size_t size)
 {
 	return -EINVAL;
 }
diff --git a/include/linux/selinux.h b/include/linux/selinux.h
deleted file mode 100644
index 44f459612690..000000000000
--- a/include/linux/selinux.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
- * SELinux services exported to the rest of the kernel.
- *
- * Author: James Morris <jmorris@redhat.com>
- *
- * Copyright (C) 2005 Red Hat, Inc., James Morris <jmorris@redhat.com>
- * Copyright (C) 2006 Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
- * Copyright (C) 2006 IBM Corporation, Timothy R. Chavez <tinytim@us.ibm.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2,
- * as published by the Free Software Foundation.
- */
-#ifndef _LINUX_SELINUX_H
-#define _LINUX_SELINUX_H
-
-struct selinux_audit_rule;
-struct audit_context;
-struct kern_ipc_perm;
-
-#ifdef CONFIG_SECURITY_SELINUX
-
-/**
- * selinux_is_enabled - is SELinux enabled?
- */
-bool selinux_is_enabled(void);
-#else
-
-static inline bool selinux_is_enabled(void)
-{
-	return false;
-}
-#endif	/* CONFIG_SECURITY_SELINUX */
-
-#endif /* _LINUX_SELINUX_H */