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Subject[PATCH 24/23] LSM: Functions for dealing with struct secids
From
Date
From: Casey Schaufler <casey@schaufler-ca.com>
Date: Fri, 11 May 2018 13:18:11 -0700
Subject: [PATCH 24/23] LSM: Functions for deling with struct secids

These are the functions that mainipulate the collection
of secids.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
security/stacking.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 119 insertions(+)
create mode 100644 security/stacking.c

diff --git a/security/stacking.c b/security/stacking.c
new file mode 100644
index 000000000000..7c9643323a1e
--- /dev/null
+++ b/security/stacking.c
@@ -0,0 +1,119 @@
+/*
+ * Security secid functions
+ *
+ * Copyright (C) 2018 Casey Schaufler <casey@schaufler-ca.com>
+ * Copyright (C) 2018 Intel
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/security.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/netlabel.h>
+
+/*
+ * A secids structure contains all of the modules specific
+ * secids and the secmark used to represent the combination
+ * of module specific secids. Code that uses secmarks won't
+ * know or care about module specific secids, and won't have
+ * set them in the secids nor will it look at the module specific
+ * values. Modules won't care about the secmark. If there's only
+ * one module that uses secids the mapping is one-to-one. The
+ * general case is not so simple.
+ */
+
+void secid_from_skb(struct secids *secid, const struct sk_buff *skb)
+{
+ struct secids *se;
+
+ se = skb->sk->sk_security;
+ if (se)
+ *secid = *se;
+}
+EXPORT_SYMBOL(secid_from_skb);
+
+void secid_to_skb(struct secids *secid, struct sk_buff *skb)
+{
+ struct secids *se;
+
+ se = skb->sk->sk_security;
+ if (se)
+ *se = *secid;
+}
+EXPORT_SYMBOL(secid_to_skb);
+
+bool secid_valid(const struct secids *secid)
+{
+#ifdef CONFIG_SECURITY_SELINUX
+ if (secid->selinux)
+ return true;
+#endif
+#ifdef CONFIG_SECURITY_SMACK
+ if (secid->smack)
+ return true;
+#endif
+ return false;
+}
+
+#ifdef CONFIG_NETLABEL
+/**
+ * lsm_sock_vet_attr - does the netlabel agree with what other LSMs want
+ * @sk: the socket in question
+ * @secattr: the desired netlabel security attributes
+ * @flags: which LSM is making the request
+ *
+ * Determine whether the calling LSM can set the security attributes
+ * on the socket without interferring with what has already been set
+ * by other LSMs. The first LSM calling will always be allowed. An
+ * LSM that resets itself will also be allowed. It will require careful
+ * configuration for any other case to succeed.
+ *
+ * If @secattr is NULL the check is for deleting the attribute.
+ *
+ * Returns 0 if there is agreement, -EACCES if there is conflict,
+ * and any error from the netlabel system.
+ */
+int lsm_sock_vet_attr(struct sock *sk, struct netlbl_lsm_secattr *secattr,
+ u32 flags)
+{
+ struct secids *se = sk->sk_security;
+ struct netlbl_lsm_secattr asis;
+ int rc;
+
+ /*
+ * First in always shows as allowed.
+ * Changing what this module has set is OK, too.
+ */
+ if (se->flags == 0 || se->flags == flags) {
+ se->flags = flags;
+ return 0;
+ }
+
+ netlbl_secattr_init(&asis);
+ rc = netlbl_sock_getattr(sk, &asis);
+
+ switch (rc) {
+ case 0:
+ /*
+ * Can't delete another modules's attributes or
+ * change them if they don't match well enough.
+ */
+ if (secattr == NULL || !netlbl_secattr_equal(secattr, &asis))
+ rc = -EACCES;
+ else
+ se->flags = flags;
+ break;
+ case -ENOMSG:
+ se->flags = flags;
+ rc = 0;
+ break;
+ default:
+ break;
+ }
+ netlbl_secattr_destroy(&asis);
+ return rc;
+}
+#endif /* CONFIG_NETLABEL */
--
2.14.3

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