[PATCH] Smack: fix domain transfer issues

[Jarkko Sakkinen <jarkko.sakkinen@intel.com>]

When domain changes, Smack should check for ptracing
and shared state. Additionally, it should clear unsafe
personality bits and turn on the secureexec bit. This
patch addresses these issues.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
---
 security/smack/smack.h     |    5 ++++
 security/smack/smack_lsm.c |   46 ++++++++++++++++++++++++++++++++++---------
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 174d3be..7b37615 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -187,6 +187,11 @@ struct smack_known {
 #define SMK_NUM_ACCESS_TYPE 4
 
 /*
+ * Passed in the bprm->unsafe field
+ */
+#define SMK_SECUREEXEC_NEEDED 0x8000
+
+/*
  * Smack audit data; is empty if CONFIG_AUDIT not set
  * to save some stack
  */
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 2e71c3f..b3766ac 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -5,12 +5,13 @@
  *
  *  Authors:
  *	Casey Schaufler <casey@schaufler-ca.com>
- *	Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com>
+ *	Jarkko Sakkinen <jarkko.sakkinen@intel.com>
  *
  *  Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
  *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
  *                Paul Moore <paul@paul-moore.com>
  *  Copyright (C) 2010 Nokia Corporation
+ *  Copyright (C) 2011 Intel Corporation.
  *
  *	This program is free software; you can redistribute it and/or modify
  *	it under the terms of the GNU General Public License version 2,
@@ -441,11 +442,17 @@ static int smack_sb_umount(struct vfsmount *mnt, int flags)
  * BPRM hooks
  */
 
+/**
+ * smack_bprm_set_creds - Smack exec that handles the domain transfer.
+ * @bprm: binprm for exec
+ *
+ * Returns 0 on success.
+ */
 static int smack_bprm_set_creds(struct linux_binprm *bprm)
 {
+	struct inode *inode = bprm->file->f_path.dentry->d_inode;
 	struct task_smack *tsp = bprm->cred->security;
 	struct inode_smack *isp;
-	struct dentry *dp;
 	int rc;
 
 	rc = cap_bprm_set_creds(bprm);
@@ -455,22 +462,40 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	if (bprm->cred_prepared)
 		return 0;
 
-	if (bprm->file == NULL || bprm->file->f_dentry == NULL)
-		return 0;
-
-	dp = bprm->file->f_dentry;
+	isp = inode->i_security;
 
-	if (dp->d_inode == NULL)
+	if (isp->smk_task == NULL || isp->smk_task == tsp->smk_task)
 		return 0;
 
-	isp = dp->d_inode->i_security;
+	if (bprm->unsafe & LSM_UNSAFE_SHARE)
+		return -EPERM;
 
-	if (isp->smk_task != NULL)
-		tsp->smk_task = isp->smk_task;
+	if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP))
+		return -EPERM;
+
+	tsp->smk_task = isp->smk_task;
+	bprm->per_clear |= PER_CLEAR_ON_SETID;
+	bprm->unsafe |= SMK_SECUREEXEC_NEEDED;
 
 	return 0;
 }
 
+/**
+ * smack_bprm_secureexec - Return the decision to use secureexec.
+ * @bprm: binprm for exec
+ *
+ * Returns 0 on success.
+ */
+static int smack_bprm_secureexec(struct linux_binprm *bprm)
+{
+	int ret = cap_bprm_secureexec(bprm);
+
+	if (!ret && (bprm->unsafe & SMK_SECUREEXEC_NEEDED))
+		ret = 1;
+
+	return ret;
+}
+
 /*
  * Inode hooks
  */
@@ -3452,6 +3477,7 @@ struct security_operations smack_ops = {
 	.sb_umount = 			smack_sb_umount,
 
 	.bprm_set_creds =		smack_bprm_set_creds,
+	.bprm_secureexec =		smack_bprm_secureexec,
 
 	.inode_alloc_security = 	smack_inode_alloc_security,
 	.inode_free_security = 		smack_inode_free_security,
-- 
1.7.4.1