lsm: replace context+len with lsm_context

Replace the (secctx,seclen) pointer pair with a single
lsm_context pointer to allow return of the LSM identifier
along with the context and context length. This allows
security_release_secctx() to know how to release the
context. Callers have been modified to use or save the
returned data from the new structure.

security_secid_to_secctx() and security_lsmproc_to_secctx()
will now return the length value on success instead of 0.

Cc: netdev@vger.kernel.org
Cc: audit@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org
Cc: Todd Kjos <tkjos@google.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject tweak, kdoc fix, signedness fix from Dan Carpenter]
Signed-off-by: Paul Moore <paul@paul-moore.com>

5 files changed, 74 insertions, 59 deletions

diff --git a/security/apparmor/include/secid.h b/security/apparmor/include/secid.h
index 1bcde2f45f24..6025d3849cf8 100644
--- a/security/apparmor/include/secid.h
+++ b/security/apparmor/include/secid.h
@@ -25,9 +25,8 @@ struct aa_label;
 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_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
-			       u32 *seclen);
+int apparmor_secid_to_secctx(u32 secid, struct lsm_context *cp);
+int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp);
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
 void apparmor_release_secctx(struct lsm_context *cp);
 
diff --git a/security/apparmor/secid.c b/security/apparmor/secid.c
index 43e4dab7f6e6..b08969ec34b7 100644
--- a/security/apparmor/secid.c
+++ b/security/apparmor/secid.c
@@ -47,23 +47,21 @@ struct aa_label *aa_secid_to_label(u32 secid)
 	return xa_load(&aa_secids, secid);
 }
 
-static int apparmor_label_to_secctx(struct aa_label *label, char **secdata,
-				    u32 *seclen)
+static int apparmor_label_to_secctx(struct aa_label *label,
+				    struct lsm_context *cp)
 {
 	/* TODO: cache secctx and ref count so we don't have to recreate */
 	int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
 	int len;
 
-	AA_BUG(!seclen);
-
 	if (!label)
 		return -EINVAL;
 
 	if (apparmor_display_secid_mode)
 		flags |= FLAG_SHOW_MODE;
 
-	if (secdata)
-		len = aa_label_asxprint(secdata, root_ns, label,
+	if (cp)
+		len = aa_label_asxprint(&cp->context, root_ns, label,
 					flags, GFP_ATOMIC);
 	else
 		len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
@@ -71,26 +69,28 @@ static int apparmor_label_to_secctx(struct aa_label *label, char **secdata,
 	if (len < 0)
 		return -ENOMEM;
 
-	*seclen = len;
+	if (cp) {
+		cp->len = len;
+		cp->id = LSM_ID_APPARMOR;
+	}
 
-	return 0;
+	return len;
 }
 
-int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+int apparmor_secid_to_secctx(u32 secid, struct lsm_context *cp)
 {
 	struct aa_label *label = aa_secid_to_label(secid);
 
-	return apparmor_label_to_secctx(label, secdata, seclen);
+	return apparmor_label_to_secctx(label, cp);
 }
 
-int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
-			       u32 *seclen)
+int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp)
 {
 	struct aa_label *label;
 
 	label = prop->apparmor.label;
 
-	return apparmor_label_to_secctx(label, secdata, seclen);
+	return apparmor_label_to_secctx(label, cp);
 }
 
 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
diff --git a/security/security.c b/security/security.c
index b7f8ec93f6f0..1edf8fb2046c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -4304,40 +4304,36 @@ EXPORT_SYMBOL(security_ismaclabel);
 /**
  * security_secid_to_secctx() - Convert a secid to a secctx
  * @secid: secid
- * @secdata: secctx
- * @seclen: secctx length
+ * @cp: the LSM context
  *
- * Convert secid to security context.  If @secdata is NULL the length of the
- * result will be returned in @seclen, but no @secdata will be returned.  This
+ * Convert secid to security context.  If @cp is NULL the length of the
+ * result will be returned, but no data 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.
+ * the next call which actually allocates and returns the data.
  *
- * Return: Return 0 on success, error on failure.
+ * Return: Return length of data on success, error on failure.
  */
-int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+int security_secid_to_secctx(u32 secid, struct lsm_context *cp)
 {
-	return call_int_hook(secid_to_secctx, secid, secdata, seclen);
+	return call_int_hook(secid_to_secctx, secid, cp);
 }
 EXPORT_SYMBOL(security_secid_to_secctx);
 
 /**
  * security_lsmprop_to_secctx() - Convert a lsm_prop to a secctx
  * @prop: lsm specific information
- * @secdata: secctx
- * @seclen: secctx length
+ * @cp: the LSM context
  *
- * Convert a @prop 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.
+ * Convert a @prop entry to security context.  If @cp is NULL the
+ * length of the result 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 @cp.
  *
- * Return: Return 0 on success, error on failure.
+ * Return: Return length of data on success, error on failure.
  */
-int security_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
-			       u32 *seclen)
+int security_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp)
 {
-	return call_int_hook(lsmprop_to_secctx, prop, secdata, seclen);
+	return call_int_hook(lsmprop_to_secctx, prop, cp);
 }
 EXPORT_SYMBOL(security_lsmprop_to_secctx);
 
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index aabc724f4d44..ddc24db7c0b2 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6640,15 +6640,28 @@ static int selinux_ismaclabel(const char *name)
 	return (strcmp(name, XATTR_SELINUX_SUFFIX) == 0);
 }
 
-static int selinux_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+static int selinux_secid_to_secctx(u32 secid, struct lsm_context *cp)
 {
-	return security_sid_to_context(secid, secdata, seclen);
+	u32 seclen;
+	int ret;
+
+	if (cp) {
+		cp->id = LSM_ID_SELINUX;
+		ret = security_sid_to_context(secid, &cp->context, &cp->len);
+		if (ret < 0)
+			return ret;
+		return cp->len;
+	}
+	ret = security_sid_to_context(secid, NULL, &seclen);
+	if (ret < 0)
+		return ret;
+	return seclen;
 }
 
-static int selinux_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
-				     u32 *seclen)
+static int selinux_lsmprop_to_secctx(struct lsm_prop *prop,
+				     struct lsm_context *cp)
 {
-	return selinux_secid_to_secctx(prop->selinux.secid, secdata, seclen);
+	return selinux_secid_to_secctx(prop->selinux.secid, cp);
 }
 
 static int selinux_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0c476282e279..4084f99c493c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4818,40 +4818,47 @@ static int smack_ismaclabel(const char *name)
 }
 
 /**
+ * smack_to_secctx - fill a lsm_context
+ * @skp: Smack label
+ * @cp: destination
+ *
+ * Fill the passed @cp and return the length of the string
+ */
+static int smack_to_secctx(struct smack_known *skp, struct lsm_context *cp)
+{
+	int len = strlen(skp->smk_known);
+
+	if (cp) {
+		cp->context = skp->smk_known;
+		cp->len = len;
+		cp->id = LSM_ID_SMACK;
+	}
+	return len;
+}
+
+/**
  * smack_secid_to_secctx - return the smack label for a secid
  * @secid: incoming integer
- * @secdata: destination
- * @seclen: how long it is
+ * @cp: destination
  *
  * Exists for networking code.
  */
-static int smack_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
+static int smack_secid_to_secctx(u32 secid, struct lsm_context *cp)
 {
-	struct smack_known *skp = smack_from_secid(secid);
-
-	if (secdata)
-		*secdata = skp->smk_known;
-	*seclen = strlen(skp->smk_known);
-	return 0;
+	return smack_to_secctx(smack_from_secid(secid), cp);
 }
 
 /**
  * smack_lsmprop_to_secctx - return the smack label
  * @prop: includes incoming Smack data
- * @secdata: destination
- * @seclen: how long it is
+ * @cp: destination
  *
  * Exists for audit code.
  */
-static int smack_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
-				   u32 *seclen)
+static int smack_lsmprop_to_secctx(struct lsm_prop *prop,
+				   struct lsm_context *cp)
 {
-	struct smack_known *skp = prop->smack.skp;
-
-	if (secdata)
-		*secdata = skp->smk_known;
-	*seclen = strlen(skp->smk_known);
-	return 0;
+	return smack_to_secctx(prop->smack.skp, cp);
 }
 
 /**