SELinux: check open perms in dentry_open not inode_permission

Some operations, like searching a directory path or connecting a unix domain
socket, make explicit calls into inode_permission.  Our choices are to
either try to come up with a signature for all of the explicit calls to
inode_permission and do not check open on those, or to move the open checks to
dentry_open where we know this is always an open operation.  This patch moves
the checks to dentry_open.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/hooks.c

@@ -1686,15 +1686,39 @@ static inline u32 file_mask_to_av(int mode, int mask)
 	return av;
 }
 
+/* Convert a Linux file to an access vector. */
+static inline u32 file_to_av(struct file *file)
+{
+	u32 av = 0;
+
+	if (file->f_mode & FMODE_READ)
+		av |= FILE__READ;
+	if (file->f_mode & FMODE_WRITE) {
+		if (file->f_flags & O_APPEND)
+			av |= FILE__APPEND;
+		else
+			av |= FILE__WRITE;
+	}
+	if (!av) {
+		/*
+		 * Special file opened with flags 3 for ioctl-only use.
+		 */
+		av = FILE__IOCTL;
+	}
+
+	return av;
+}
+
 /*
- * Convert a file mask to an access vector and include the correct open
+ * Convert a file to an access vector and include the correct open
  * open permission.
  */
-static inline u32 open_file_mask_to_av(int mode, int mask)
+static inline u32 open_file_to_av(struct file *file)
 {
-	u32 av = file_mask_to_av(mode, mask);
+	u32 av = file_to_av(file);
 
 	if (selinux_policycap_openperm) {
+		mode_t mode = file->f_path.dentry->d_inode->i_mode;
 		/*
 		 * lnk files and socks do not really have an 'open'
 		 */
@@ -1710,34 +1734,11 @@ static inline u32 open_file_mask_to_av(int mode, int mask)
 			av |= DIR__OPEN;
 		else
 			printk(KERN_ERR "SELinux: WARNING: inside %s with "
-				"unknown mode:%x\n", __func__, mode);
+				"unknown mode:%o\n", __func__, mode);
 	}
 	return av;
 }
 
-/* Convert a Linux file to an access vector. */
-static inline u32 file_to_av(struct file *file)
-{
-	u32 av = 0;
-
-	if (file->f_mode & FMODE_READ)
-		av |= FILE__READ;
-	if (file->f_mode & FMODE_WRITE) {
-		if (file->f_flags & O_APPEND)
-			av |= FILE__APPEND;
-		else
-			av |= FILE__WRITE;
-	}
-	if (!av) {
-		/*
-		 * Special file opened with flags 3 for ioctl-only use.
-		 */
-		av = FILE__IOCTL;
-	}
-
-	return av;
-}
-
 /* Hook functions begin here. */
 
 static int selinux_ptrace_may_access(struct task_struct *child,
@@ -2654,7 +2655,7 @@ static int selinux_inode_permission(struct inode *inode, int mask)
 	}
 
 	return inode_has_perm(current, inode,
-			       open_file_mask_to_av(inode->i_mode, mask), NULL);
+			      file_mask_to_av(inode->i_mode, mask), NULL);
 }
 
 static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr)
@@ -3170,7 +3171,7 @@ static int selinux_dentry_open(struct file *file)
 	 * new inode label or new policy.
 	 * This check is not redundant - do not remove.
 	 */
-	return inode_has_perm(current, inode, file_to_av(file), NULL);
+	return inode_has_perm(current, inode, open_file_to_av(file), NULL);
 }
 
 /* task security operations */