SELinux: Abstract use of inode security blob

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>
Signed-off-by: Kees Cook <keescook@chromium.org>

3 files changed, 21 insertions, 15 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 632813821da6..2d691e8dfbbf 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -273,7 +273,7 @@ static int __inode_security_revalidate(struct inode *inode,
                                        struct dentry *dentry,
                                        bool may_sleep)
 {
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
 
         might_sleep_if(may_sleep);
 
@@ -294,7 +294,7 @@ static int __inode_security_revalidate(struct inode *inode,
 
 static struct inode_security_struct *inode_security_novalidate(struct inode *inode)
 {
-        return inode->i_security;
+        return selinux_inode(inode);
 }
 
 static struct inode_security_struct *inode_security_rcu(struct inode *inode, bool rcu)
@@ -304,7 +304,7 @@ static struct inode_security_struct *inode_security_rcu(struct inode *inode, boo
         error = __inode_security_revalidate(inode, NULL, !rcu);
         if (error)
                 return ERR_PTR(error);
-        return inode->i_security;
+        return selinux_inode(inode);
 }
 
 /*
@@ -313,14 +313,14 @@ static struct inode_security_struct *inode_security_rcu(struct inode *inode, boo
 static struct inode_security_struct *inode_security(struct inode *inode)
 {
         __inode_security_revalidate(inode, NULL, true);
-        return inode->i_security;
+        return selinux_inode(inode);
 }
 
 static struct inode_security_struct *backing_inode_security_novalidate(struct dentry *dentry)
 {
         struct inode *inode = d_backing_inode(dentry);
 
-        return inode->i_security;
+        return selinux_inode(inode);
 }
 
 /*
@@ -331,7 +331,7 @@ static struct inode_security_struct *backing_inode_security(struct dentry *dentr
         struct inode *inode = d_backing_inode(dentry);
 
         __inode_security_revalidate(inode, dentry, true);
-        return inode->i_security;
+        return selinux_inode(inode);
 }
 
 static void inode_free_rcu(struct rcu_head *head)
@@ -344,7 +344,7 @@ static void inode_free_rcu(struct rcu_head *head)
 
 static void inode_free_security(struct inode *inode)
 {
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
         struct superblock_security_struct *sbsec = inode->i_sb->s_security;
 
         /*
@@ -1354,7 +1354,7 @@ static int selinux_genfs_get_sid(struct dentry *dentry,
 static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dentry)
 {
         struct superblock_security_struct *sbsec = NULL;
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
         u32 task_sid, sid = 0;
         u16 sclass;
         struct dentry *dentry;
@@ -1654,7 +1654,7 @@ static int inode_has_perm(const struct cred *cred,
                 return 0;
 
         sid = cred_sid(cred);
-        isec = inode->i_security;
+        isec = selinux_inode(inode);
 
         return avc_has_perm(&selinux_state,
                             sid, isec->sid, isec->sclass, perms, adp);
@@ -2816,7 +2816,7 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 
         /* Possibly defer initialization to selinux_complete_init. */
         if (sbsec->flags & SE_SBINITIALIZED) {
-                struct inode_security_struct *isec = inode->i_security;
+                struct inode_security_struct *isec = selinux_inode(inode);
                 isec->sclass = inode_mode_to_security_class(inode->i_mode);
                 isec->sid = newsid;
                 isec->initialized = LABEL_INITIALIZED;
@@ -2916,7 +2916,7 @@ static noinline int audit_inode_permission(struct inode *inode,
                                            unsigned flags)
 {
         struct common_audit_data ad;
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
         int rc;
 
         ad.type = LSM_AUDIT_DATA_INODE;
@@ -3936,7 +3936,7 @@ static int selinux_task_kill(struct task_struct *p, struct kernel_siginfo *info,
 static void selinux_task_to_inode(struct task_struct *p,
                                   struct inode *inode)
 {
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
         u32 sid = task_sid(p);
 
         spin_lock(&isec->lock);
@@ -6318,7 +6318,7 @@ static void selinux_release_secctx(char *secdata, u32 seclen)
 
 static void selinux_inode_invalidate_secctx(struct inode *inode)
 {
-        struct inode_security_struct *isec = inode->i_security;
+        struct inode_security_struct *isec = selinux_inode(inode);
 
         spin_lock(&isec->lock);
         isec->initialized = LABEL_INVALID;
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 96374dbf4ace..26b4ff6b4d81 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -170,4 +170,10 @@ static inline struct file_security_struct *selinux_file(const struct file *file)
         return file->f_security + selinux_blob_sizes.lbs_file;
 }
 
+static inline struct inode_security_struct *selinux_inode(
+                                                const struct inode *inode)
+{
+        return inode->i_security;
+}
+
 #endif /* _SELINUX_OBJSEC_H_ */
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index f3a5a138a096..145ee62f205a 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1378,7 +1378,7 @@ static int sel_make_bools(struct selinux_fs_info *fsi)
                         goto out;
                 }
 
-                isec = (struct inode_security_struct *)inode->i_security;
+                isec = selinux_inode(inode);
                 ret = security_genfs_sid(fsi->state, "selinuxfs", page,
                                          SECCLASS_FILE, &sid);
                 if (ret) {
@@ -1953,7 +1953,7 @@ static int sel_fill_super(struct super_block *sb, void *data, int silent)
         }
 
         inode->i_ino = ++fsi->last_ino;
-        isec = (struct inode_security_struct *)inode->i_security;
+        isec = selinux_inode(inode);
         isec->sid = SECINITSID_DEVNULL;
         isec->sclass = SECCLASS_CHR_FILE;
         isec->initialized = LABEL_INITIALIZED;