From: Casey Schaufler <casey@schaufler-ca.com>
Date: Sat, 22 Sep 2018 00:17:25 +0000 (-0700)
Subject: SELinux: Remove cred security blob poisoning
X-Git-Tag: v5.1-rc1~69^2~20^2~15
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=98c88651365767c72ec6dc672072423bc19a39aa;p=linux.git

SELinux: Remove cred security blob poisoning

The SELinux specific credential poisioning only makes sense
if SELinux is managing the credentials. As the intent of this
patch set is to move the blob management out of the modules
and into the infrastructure, the SELinux specific code has
to go. The poisioning could be introduced into the infrastructure
at some later date.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---

diff --git a/kernel/cred.c b/kernel/cred.c
index 21f4a97085b4..45d77284aed0 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -760,19 +760,6 @@ bool creds_are_invalid(const struct cred *cred)
 {
 	if (cred->magic != CRED_MAGIC)
 		return true;
-#ifdef CONFIG_SECURITY_SELINUX
-	/*
-	 * cred->security == NULL if security_cred_alloc_blank() or
-	 * security_prepare_creds() returned an error.
-	 */
-	if (selinux_is_enabled() && cred->security) {
-		if ((unsigned long) cred->security < PAGE_SIZE)
-			return true;
-		if ((*(u32 *)cred->security & 0xffffff00) ==
-		    (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
-			return true;
-	}
-#endif
 	return false;
 }
 EXPORT_SYMBOL(creds_are_invalid);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index beec1de5c2da..ad227177550b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3708,12 +3708,6 @@ static void selinux_cred_free(struct cred *cred)
 {
 	struct task_security_struct *tsec = selinux_cred(cred);
 
-	/*
-	 * cred->security == NULL if security_cred_alloc_blank() or
-	 * security_prepare_creds() returned an error.
-	 */
-	BUG_ON(cred->security && (unsigned long) cred->security < PAGE_SIZE);
-	cred->security = (void *) 0x7UL;
 	kfree(tsec);
 }