[PATCH 03/13] LSM: Add lsmblob_to_secctx hook

[Casey Schaufler <casey@schaufler-ca.com>]

Add a new hook security_lsmblob_to_secctx() and its LSM specific
implementations. The LSM specific code will use the lsmblob element
allocated for that module. This allows for the possibility that more
than one module may be called upon to translate a secid to a string,
as can occur in the audit code.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/lsm_hook_defs.h     |  2 ++
 include/linux/security.h          | 11 +++++++++-
 security/apparmor/include/secid.h |  2 ++
 security/apparmor/lsm.c           |  1 +
 security/apparmor/secid.c         | 36 +++++++++++++++++++++++++++++++
 security/security.c               | 30 ++++++++++++++++++++++++++
 security/selinux/hooks.c          | 16 ++++++++++++--
 security/smack/smack_lsm.c        | 31 +++++++++++++++++++++-----
 8 files changed, 121 insertions(+), 8 deletions(-)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 1d3bdf71109e..3e5f6baa7b9f 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -291,6 +291,8 @@ LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size)
 LSM_HOOK(int, 0, ismaclabel, const char *name)
 LSM_HOOK(int, -EOPNOTSUPP, secid_to_secctx, u32 secid, char **secdata,
 	 u32 *seclen)
+LSM_HOOK(int, -EOPNOTSUPP, lsmblob_to_secctx, struct lsmblob *blob,
+	 char **secdata, u32 *seclen)
 LSM_HOOK(int, 0, secctx_to_secid, const char *secdata, u32 seclen, u32 *secid)
 LSM_HOOK(void, LSM_RET_VOID, release_secctx, char *secdata, u32 seclen)
 LSM_HOOK(void, LSM_RET_VOID, inode_invalidate_secctx, struct inode *inode)
diff --git a/include/linux/security.h b/include/linux/security.h
index c0ed2119a622..457fafc32fb0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -520,6 +520,8 @@ int security_setprocattr(int lsmid, 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);
+int security_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+			       u32 *seclen);
 int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void security_release_secctx(char *secdata, u32 seclen);
 void security_inode_invalidate_secctx(struct inode *inode);
@@ -1461,7 +1463,14 @@ static inline int security_ismaclabel(const char *name)
 	return 0;
 }
 
-static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+static inline int security_secid_to_secctx(u32 secid, char **secdata,
+					   u32 *seclen)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int security_lsmblob_to_secctx(struct lsmblob *blob,
+					     char **secdata, u32 *seclen)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/security/apparmor/include/secid.h b/security/apparmor/include/secid.h
index a912a5d5d04f..816a425e2023 100644
--- a/security/apparmor/include/secid.h
+++ b/security/apparmor/include/secid.h
@@ -26,6 +26,8 @@ extern int apparmor_display_secid_mode;
 
 struct aa_label *aa_secid_to_label(u32 secid);
 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
+int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+			       u32 *seclen);
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void apparmor_release_secctx(char *secdata, u32 seclen);
 
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 808060f9effb..050d103f5ca5 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1532,6 +1532,7 @@ static struct security_hook_list apparmor_hooks[] __ro_after_init = {
 #endif
 
 	LSM_HOOK_INIT(secid_to_secctx, apparmor_secid_to_secctx),
+	LSM_HOOK_INIT(lsmblob_to_secctx, apparmor_lsmblob_to_secctx),
 	LSM_HOOK_INIT(secctx_to_secid, apparmor_secctx_to_secid),
 	LSM_HOOK_INIT(release_secctx, apparmor_release_secctx),
 
diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c
index 83d3d1e6d9dc..3c389e5810cd 100644
--- a/security/apparmor/secid.c
+++ b/security/apparmor/secid.c
@@ -90,6 +90,42 @@ int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 	return 0;
 }
 
+int apparmor_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+			       u32 *seclen)
+{
+	/* TODO: cache secctx and ref count so we don't have to recreate */
+	struct aa_label *label;
+	int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
+	int len;
+
+	AA_BUG(!seclen);
+
+	/* scaffolding */
+	if (!blob->apparmor.label && blob->scaffold.secid)
+		label = aa_secid_to_label(blob->scaffold.secid);
+	else
+		label = blob->apparmor.label;
+
+	if (!label)
+		return -EINVAL;
+
+	if (apparmor_display_secid_mode)
+		flags |= FLAG_SHOW_MODE;
+
+	if (secdata)
+		len = aa_label_asxprint(secdata, root_ns, label,
+					flags, GFP_ATOMIC);
+	else
+		len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
+
+	if (len < 0)
+		return -ENOMEM;
+
+	*seclen = len;
+
+	return 0;
+}
+
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 {
 	struct aa_label *label;
diff --git a/security/security.c b/security/security.c
index 64a6d6bbd1f4..bb541a3be410 100644
--- a/security/security.c
+++ b/security/security.c
@@ -4192,6 +4192,36 @@ int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 }
 EXPORT_SYMBOL(security_secid_to_secctx);
 
+/**
+ * security_lsmblob_to_secctx() - Convert a lsmblob to a secctx
+ * @blob: lsm specific information
+ * @secdata: secctx
+ * @seclen: secctx length
+ *
+ * Convert a @blob entry to security context.  If @secdata is NULL the
+ * length of the result will be returned in @seclen, but no @secdata
+ * will be returned.  This does mean that the length could change between
+ * calls to check the length and the next call which actually allocates
+ * and returns the @secdata.
+ *
+ * Return: Return 0 on success, error on failure.
+ */
+int security_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+			       u32 *seclen)
+{
+	struct security_hook_list *hp;
+	int rc;
+
+	hlist_for_each_entry(hp, &security_hook_heads.secid_to_secctx, list) {
+		rc = hp->hook.lsmblob_to_secctx(blob, secdata, seclen);
+		if (rc != LSM_RET_DEFAULT(secid_to_secctx))
+			return rc;
+	}
+
+	return LSM_RET_DEFAULT(secid_to_secctx);
+}
+EXPORT_SYMBOL(security_lsmblob_to_secctx);
+
 /**
  * security_secctx_to_secid() - Convert a secctx to a secid
  * @secdata: secctx
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 55c78c318ccd..102489e6d579 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6610,8 +6610,19 @@ static int selinux_ismaclabel(const char *name)
 
 static int selinux_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 {
-	return security_sid_to_context(secid,
-				       secdata, seclen);
+	return security_sid_to_context(secid, secdata, seclen);
+}
+
+static int selinux_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+				     u32 *seclen)
+{
+	u32 secid = blob->selinux.secid;
+
+	/* scaffolding */
+	if (!secid)
+		secid = blob->scaffold.secid;
+
+	return security_sid_to_context(secid, secdata, seclen);
 }
 
 static int selinux_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
@@ -7388,6 +7399,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
 	LSM_HOOK_INIT(inode_alloc_security, selinux_inode_alloc_security),
 	LSM_HOOK_INIT(sem_alloc_security, selinux_sem_alloc_security),
 	LSM_HOOK_INIT(secid_to_secctx, selinux_secid_to_secctx),
+	LSM_HOOK_INIT(lsmblob_to_secctx, selinux_lsmblob_to_secctx),
 	LSM_HOOK_INIT(inode_getsecctx, selinux_inode_getsecctx),
 	LSM_HOOK_INIT(sk_alloc_security, selinux_sk_alloc_security),
 	LSM_HOOK_INIT(tun_dev_alloc_security, selinux_tun_dev_alloc_security),
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 52d5ef986db8..5d74d8590862 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4787,7 +4787,7 @@ static int smack_audit_rule_known(struct audit_krule *krule)
 static int smack_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
 				  void *vrule)
 {
-	struct smack_known *skp;
+	struct smack_known *skp = blob->smack.skp;
 	char *rule = vrule;
 
 	if (unlikely(!rule)) {
@@ -4799,10 +4799,8 @@ static int smack_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
 		return 0;
 
 	/* scaffolding */
-	if (!blob->smack.skp && blob->scaffold.secid)
+	if (!skp && blob->scaffold.secid)
 		skp = smack_from_secid(blob->scaffold.secid);
-	else
-		skp = blob->smack.skp;
 
 	/*
 	 * No need to do string comparisons. If a match occurs,
@@ -4833,7 +4831,6 @@ static int smack_ismaclabel(const char *name)
 	return (strcmp(name, XATTR_SMACK_SUFFIX) == 0);
 }
 
-
 /**
  * smack_secid_to_secctx - return the smack label for a secid
  * @secid: incoming integer
@@ -4852,6 +4849,29 @@ static int smack_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 	return 0;
 }
 
+/**
+ * smack_lsmblob_to_secctx - return the smack label
+ * @blob: includes incoming Smack data
+ * @secdata: destination
+ * @seclen: how long it is
+ *
+ * Exists for audit code.
+ */
+static int smack_lsmblob_to_secctx(struct lsmblob *blob, char **secdata,
+				   u32 *seclen)
+{
+	struct smack_known *skp = blob->smack.skp;
+
+	/* scaffolding */
+	if (!skp && blob->scaffold.secid)
+		skp = smack_from_secid(blob->scaffold.secid);
+
+	if (secdata)
+		*secdata = skp->smk_known;
+	*seclen = strlen(skp->smk_known);
+	return 0;
+}
+
 /**
  * smack_secctx_to_secid - return the secid for a smack label
  * @secdata: smack label
@@ -5208,6 +5228,7 @@ static struct security_hook_list smack_hooks[] __ro_after_init = {
 
 	LSM_HOOK_INIT(ismaclabel, smack_ismaclabel),
 	LSM_HOOK_INIT(secid_to_secctx, smack_secid_to_secctx),
+	LSM_HOOK_INIT(lsmblob_to_secctx, smack_lsmblob_to_secctx),
 	LSM_HOOK_INIT(secctx_to_secid, smack_secctx_to_secid),
 	LSM_HOOK_INIT(inode_notifysecctx, smack_inode_notifysecctx),
 	LSM_HOOK_INIT(inode_setsecctx, smack_inode_setsecctx),
-- 
2.41.0