Before the inode_xattr_getsecurity call was removed the caller would
concatenate the security namespace prefix and the suffix provided by the lsm to
obtain the security xattr. This hook provides the functionality to obtain the full
LSM xattr name. The patch also provides implementations for the dummy security
module and SELinux. This method is used instead of restoring the old method
since it only requires an offset into the returned pointer to obtain the
suffix. This approach is more efficient than concatenating the security xattr
namespace string with the suffix to get a usable string.

Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
---
 include/linux/security.h |    8 ++++++++
 security/dummy.c         |    6 ++++++
 security/security.c      |    6 ++++++
 security/selinux/hooks.c |   10 ++++++++--
 4 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index fe52cde..c80bee4 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1394,6 +1394,7 @@ struct security_operations {
 	int (*secid_to_secctx)(u32 secid, char **secdata, u32 *seclen);
 	int (*secctx_to_secid)(char *secdata, u32 seclen, u32 *secid);
 	void (*release_secctx)(char *secdata, u32 seclen);
+	const char *(*maclabel_getname) (void);
 
 #ifdef CONFIG_SECURITY_NETWORK
 	int (*unix_stream_connect) (struct socket * sock,
@@ -1633,6 +1634,7 @@ int security_netlink_recv(struct sk_buff *skb, int cap);
 int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
 int security_secctx_to_secid(char *secdata, u32 seclen, u32 *secid);
 void security_release_secctx(char *secdata, u32 seclen);
+const char *security_maclabel_getname(void);
 
 #else /* CONFIG_SECURITY */
 
@@ -2316,6 +2318,12 @@ static inline int security_secctx_to_secid(char *secdata,
 static inline void security_release_secctx(char *secdata, u32 seclen)
 {
 }
+
+static inline const char *security_maclabel_getname(void)
+{
+	return NULL;
+}
+
 #endif	/* CONFIG_SECURITY */
 
 #ifdef CONFIG_SECURITY_NETWORK
diff --git a/security/dummy.c b/security/dummy.c
index 649326b..928ef41 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -960,6 +960,11 @@ static void dummy_release_secctx(char *secdata, u32 seclen)
 {
 }
 
+static const char *dummy_maclabel_getname(void)
+{
+	return NULL;
+}
+
 #ifdef CONFIG_KEYS
 static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx,
 				  unsigned long flags)
@@ -1118,6 +1123,7 @@ void security_fixup_ops (struct security_operations *ops)
  	set_to_dummy_if_null(ops, secid_to_secctx);
 	set_to_dummy_if_null(ops, secctx_to_secid);
  	set_to_dummy_if_null(ops, release_secctx);
+	set_to_dummy_if_null(ops, maclabel_getname);
 #ifdef CONFIG_SECURITY_NETWORK
 	set_to_dummy_if_null(ops, unix_stream_connect);
 	set_to_dummy_if_null(ops, unix_may_send);
diff --git a/security/security.c b/security/security.c
index d15e56c..1a84eb1 100644
--- a/security/security.c
+++ b/security/security.c
@@ -845,6 +845,12 @@ void security_release_secctx(char *secdata, u32 seclen)
 }
 EXPORT_SYMBOL(security_release_secctx);
 
+const char *security_maclabel_getname(void)
+{
+	return security_ops->maclabel_getname();
+}
+EXPORT_SYMBOL(security_maclabel_getname);
+
 #ifdef CONFIG_SECURITY_NETWORK
 
 int security_unix_stream_connect(struct socket *sock, struct socket *other,
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 75c2e99..e7fc9c9 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5163,6 +5163,11 @@ static void selinux_release_secctx(char *secdata, u32 seclen)
 	kfree(secdata);
 }
 
+static const char *selinux_maclabel_getname(void)
+{
+      return XATTR_NAME_SELINUX;
+}
+
 #ifdef CONFIG_KEYS
 
 static int selinux_key_alloc(struct key *k, struct task_struct *tsk,
@@ -5351,8 +5356,9 @@ static struct security_operations selinux_ops = {
 	.secid_to_secctx =		selinux_secid_to_secctx,
 	.secctx_to_secid =		selinux_secctx_to_secid,
 	.release_secctx =		selinux_release_secctx,
-
-        .unix_stream_connect =		selinux_socket_unix_stream_connect,
+	.maclabel_getname =  		selinux_maclabel_getname,
+        
+	.unix_stream_connect =		selinux_socket_unix_stream_connect,
 	.unix_may_send =		selinux_socket_unix_may_send,
 
 	.socket_create =		selinux_socket_create,
-- 
1.5.3.8

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