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Subject: [PATCH v4 13/19] Smack: Abstract use of inode security blob
To:     LSM <linux-security-module@vger.kernel.org>,
        James Morris <jmorris@namei.org>,
        SE Linux <selinux@tycho.nsa.gov>,
        LKLM <linux-kernel@vger.kernel.org>,
        John Johansen <john.johansen@canonical.com>,
        Kees Cook <keescook@chromium.org>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Paul Moore <paul@paul-moore.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mic@digikod.net>,
        Salvatore Mesoraca <s.mesoraca16@gmail.com>
References: <e9bfb2d5-d987-55ce-4011-9b32ff745d36@schaufler-ca.com>
From:   Casey Schaufler <casey@schaufler-ca.com>
Message-ID: <f1642e87-e73b-e012-cfbb-127294ac5d6d@schaufler-ca.com>
Date:   Fri, 21 Sep 2018 17:19:20 -0700
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Sender: linux-kernel-owner@vger.kernel.org
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Don't use the inode->i_security pointer directly.
Provide a helper function that provides the security blob pointer.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 security/smack/smack.h     |  9 +++++++--
 security/smack/smack_lsm.c | 32 ++++++++++++++++----------------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 62a22ad8ce92..add19b7efc96 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -366,12 +366,17 @@ static inline struct smack_known **smack_file(const struct file *file)
 	return file->f_security;
 }
 
+static inline struct inode_smack *smack_inode(const struct inode *inode)
+{
+	return inode->i_security;
+}
+
 /*
  * Is the directory transmuting?
  */
 static inline int smk_inode_transmutable(const struct inode *isp)
 {
-	struct inode_smack *sip = isp->i_security;
+	struct inode_smack *sip = smack_inode(isp);
 	return (sip->smk_flags & SMK_INODE_TRANSMUTE) != 0;
 }
 
@@ -380,7 +385,7 @@ static inline int smk_inode_transmutable(const struct inode *isp)
  */
 static inline struct smack_known *smk_of_inode(const struct inode *isp)
 {
-	struct inode_smack *sip = isp->i_security;
+	struct inode_smack *sip = smack_inode(isp);
 	return sip->smk_inode;
 }
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d1430341798f..364699ad55b9 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -166,7 +166,7 @@ static int smk_bu_task(struct task_struct *otp, int mode, int rc)
 static int smk_bu_inode(struct inode *inode, int mode, int rc)
 {
 	struct task_smack *tsp = smack_cred(current_cred());
-	struct inode_smack *isp = inode->i_security;
+	struct inode_smack *isp = smack_inode(inode);
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
 	if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -198,7 +198,7 @@ static int smk_bu_file(struct file *file, int mode, int rc)
 	struct task_smack *tsp = smack_cred(current_cred());
 	struct smack_known *sskp = tsp->smk_task;
 	struct inode *inode = file_inode(file);
-	struct inode_smack *isp = inode->i_security;
+	struct inode_smack *isp = smack_inode(inode);
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
 	if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -228,7 +228,7 @@ static int smk_bu_credfile(const struct cred *cred, struct file *file,
 	struct task_smack *tsp = smack_cred(cred);
 	struct smack_known *sskp = tsp->smk_task;
 	struct inode *inode = file_inode(file);
-	struct inode_smack *isp = inode->i_security;
+	struct inode_smack *isp = smack_inode(inode);
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
 	if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -824,7 +824,7 @@ static int smack_set_mnt_opts(struct super_block *sb,
 	/*
 	 * Initialize the root inode.
 	 */
-	isp = inode->i_security;
+	isp = smack_inode(inode);
 	if (isp == NULL) {
 		isp = new_inode_smack(sp->smk_root);
 		if (isp == NULL)
@@ -912,7 +912,7 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	if (bprm->called_set_creds)
 		return 0;
 
-	isp = inode->i_security;
+	isp = smack_inode(inode);
 	if (isp->smk_task == NULL || isp->smk_task == bsp->smk_task)
 		return 0;
 
@@ -992,7 +992,7 @@ static void smack_inode_free_rcu(struct rcu_head *head)
  */
 static void smack_inode_free_security(struct inode *inode)
 {
-	struct inode_smack *issp = inode->i_security;
+	struct inode_smack *issp = smack_inode(inode);
 
 	/*
 	 * The inode may still be referenced in a path walk and
@@ -1020,7 +1020,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
 				     const struct qstr *qstr, const char **name,
 				     void **value, size_t *len)
 {
-	struct inode_smack *issp = inode->i_security;
+	struct inode_smack *issp = smack_inode(inode);
 	struct smack_known *skp = smk_of_current();
 	struct smack_known *isp = smk_of_inode(inode);
 	struct smack_known *dsp = smk_of_inode(dir);
@@ -1358,7 +1358,7 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
 				      const void *value, size_t size, int flags)
 {
 	struct smack_known *skp;
-	struct inode_smack *isp = d_backing_inode(dentry)->i_security;
+	struct inode_smack *isp = smack_inode(d_backing_inode(dentry));
 
 	if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
 		isp->smk_flags |= SMK_INODE_TRANSMUTE;
@@ -1439,7 +1439,7 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
 	if (rc != 0)
 		return rc;
 
-	isp = d_backing_inode(dentry)->i_security;
+	isp = smack_inode(d_backing_inode(dentry));
 	/*
 	 * Don't do anything special for these.
 	 *	XATTR_NAME_SMACKIPIN
@@ -1714,7 +1714,7 @@ static int smack_mmap_file(struct file *file,
 	if (unlikely(IS_PRIVATE(file_inode(file))))
 		return 0;
 
-	isp = file_inode(file)->i_security;
+	isp = smack_inode(file_inode(file));
 	if (isp->smk_mmap == NULL)
 		return 0;
 	sbsp = file_inode(file)->i_sb->s_security;
@@ -2056,7 +2056,7 @@ static int smack_kernel_act_as(struct cred *new, u32 secid)
 static int smack_kernel_create_files_as(struct cred *new,
 					struct inode *inode)
 {
-	struct inode_smack *isp = inode->i_security;
+	struct inode_smack *isp = smack_inode(inode);
 	struct task_smack *tsp = smack_cred(new);
 
 	tsp->smk_forked = isp->smk_inode;
@@ -2256,7 +2256,7 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
  */
 static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
 {
-	struct inode_smack *isp = inode->i_security;
+	struct inode_smack *isp = smack_inode(inode);
 	struct smack_known *skp = smk_of_task_struct(p);
 
 	isp->smk_inode = skp;
@@ -2719,7 +2719,7 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
 				   const void *value, size_t size, int flags)
 {
 	struct smack_known *skp;
-	struct inode_smack *nsp = inode->i_security;
+	struct inode_smack *nsp = smack_inode(inode);
 	struct socket_smack *ssp;
 	struct socket *sock;
 	int rc = 0;
@@ -3327,7 +3327,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 	if (inode == NULL)
 		return;
 
-	isp = inode->i_security;
+	isp = smack_inode(inode);
 
 	mutex_lock(&isp->smk_lock);
 	/*
@@ -4559,7 +4559,7 @@ static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
 	/*
 	 * Get label from overlay inode and set it in create_sid
 	 */
-	isp = d_inode(dentry->d_parent)->i_security;
+	isp = smack_inode(d_inode(dentry->d_parent));
 	skp = isp->smk_inode;
 	tsp->smk_task = skp;
 	*new = new_creds;
@@ -4596,7 +4596,7 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
 	/*
 	 * the attribute of the containing directory
 	 */
-	isp = d_inode(dentry->d_parent)->i_security;
+	isp = smack_inode(d_inode(dentry->d_parent));
 
 	if (isp->smk_flags & SMK_INODE_TRANSMUTE) {
 		rcu_read_lock();
-- 
2.17.1