1 files changed, 242 insertions, 98 deletions

diff --git a/security/inode.c b/security/inode.c
index 43ce6e19015f..81fb5d6dd33e 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -1,58 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *  inode.c - securityfs
  *
  *  Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
  *
- *	This program is free software; you can redistribute it and/or
- *	modify it under the terms of the GNU General Public License version
- *	2 as published by the Free Software Foundation.
- *
  *  Based on fs/debugfs/inode.c which had the following copyright notice:
  *    Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
  *    Copyright (C) 2004 IBM Inc.
  */
 
 /* #define DEBUG */
-#include <linux/module.h>
+#include <linux/sysfs.h>
+#include <linux/kobject.h>
 #include <linux/fs.h>
+#include <linux/fs_context.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>
 #include <linux/init.h>
 #include <linux/namei.h>
 #include <linux/security.h>
+#include <linux/lsm_hooks.h>
 #include <linux/magic.h>
 
+#include "lsm.h"
+
 static struct vfsmount *mount;
 static int mount_count;
 
-static inline int positive(struct dentry *dentry)
+static void securityfs_free_inode(struct inode *inode)
 {
-	return dentry->d_inode && !d_unhashed(dentry);
+	if (S_ISLNK(inode->i_mode))
+		kfree(inode->i_link);
+	free_inode_nonrcu(inode);
 }
 
-static int fill_super(struct super_block *sb, void *data, int silent)
+static const struct super_operations securityfs_super_operations = {
+	.statfs		= simple_statfs,
+	.free_inode	= securityfs_free_inode,
+};
+
+static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
-	static struct tree_descr files[] = {{""}};
+	static const struct tree_descr files[] = {{""}};
+	int error;
+
+	error = simple_fill_super(sb, SECURITYFS_MAGIC, files);
+	if (error)
+		return error;
 
-	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
+	sb->s_op = &securityfs_super_operations;
+
+	return 0;
 }
 
-static struct dentry *get_sb(struct file_system_type *fs_type,
-		  int flags, const char *dev_name,
-		  void *data)
+static int securityfs_get_tree(struct fs_context *fc)
 {
-	return mount_single(fs_type, flags, data, fill_super);
+	return get_tree_single(fc, securityfs_fill_super);
+}
+
+static const struct fs_context_operations securityfs_context_ops = {
+	.get_tree	= securityfs_get_tree,
+};
+
+static int securityfs_init_fs_context(struct fs_context *fc)
+{
+	fc->ops = &securityfs_context_ops;
+	return 0;
 }
 
 static struct file_system_type fs_type = {
 	.owner =	THIS_MODULE,
 	.name =		"securityfs",
-	.mount =	get_sb,
-	.kill_sb =	kill_litter_super,
+	.init_fs_context = securityfs_init_fs_context,
+	.kill_sb =	kill_anon_super,
 };
 
 /**
- * securityfs_create_file - create a file in the securityfs filesystem
+ * securityfs_create_dentry - create a dentry in the securityfs filesystem
  *
  * @name: a pointer to a string containing the name of the file to create.
  * @mode: the permission that the file should have
@@ -64,87 +88,116 @@ static struct file_system_type fs_type = {
  *        the open() call.
  * @fops: a pointer to a struct file_operations that should be used for
  *        this file.
+ * @iops: a point to a struct of inode_operations that should be used for
+ *        this file/dir
  *
- * This is the basic "create a file" function for securityfs.  It allows for a
- * wide range of flexibility in creating a file, or a directory (if you
- * want to create a directory, the securityfs_create_dir() function is
- * recommended to be used instead).
+ * This is the basic "create a file/dir/symlink" function for
+ * securityfs.  It allows for a wide range of flexibility in creating
+ * a file, or a directory (if you want to create a directory, the
+ * securityfs_create_dir() function is recommended to be used
+ * instead).
  *
  * This function returns a pointer to a dentry if it succeeds.  This
- * pointer must be passed to the securityfs_remove() function when the file is
- * to be removed (no automatic cleanup happens if your module is unloaded,
- * you are responsible here).  If an error occurs, the function will return
- * the erorr value (via ERR_PTR).
+ * pointer must be passed to the securityfs_remove() function when the
+ * file is to be removed (no automatic cleanup happens if your module
+ * is unloaded, you are responsible here).  If an error occurs, the
+ * function will return the error value (via ERR_PTR).
  *
  * If securityfs is not enabled in the kernel, the value %-ENODEV is
  * returned.
  */
-struct dentry *securityfs_create_file(const char *name, umode_t mode,
-				   struct dentry *parent, void *data,
-				   const struct file_operations *fops)
+static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
+					struct dentry *parent, void *data,
+					const struct file_operations *fops,
+					const struct inode_operations *iops)
 {
 	struct dentry *dentry;
-	int is_dir = S_ISDIR(mode);
 	struct inode *dir, *inode;
 	int error;
+	bool pinned = false;
 
-	if (!is_dir) {
-		BUG_ON(!fops);
+	if (!(mode & S_IFMT))
 		mode = (mode & S_IALLUGO) | S_IFREG;
-	}
 
 	pr_debug("securityfs: creating file '%s'\n",name);
 
-	error = simple_pin_fs(&fs_type, &mount, &mount_count);
-	if (error)
-		return ERR_PTR(error);
-
-	if (!parent)
+	if (!parent) {
+		error = simple_pin_fs(&fs_type, &mount, &mount_count);
+		if (error)
+			return ERR_PTR(error);
+		pinned = true;
 		parent = mount->mnt_root;
+	}
 
-	dir = parent->d_inode;
-
-	mutex_lock(&dir->i_mutex);
-	dentry = lookup_one_len(name, parent, strlen(name));
-	if (IS_ERR(dentry))
+	inode = new_inode(parent->d_sb);
+	if (unlikely(!inode)) {
+		dentry = ERR_PTR(-ENOMEM);
 		goto out;
-
-	if (dentry->d_inode) {
-		error = -EEXIST;
-		goto out1;
 	}
 
-	inode = new_inode(dir->i_sb);
-	if (!inode) {
-		error = -ENOMEM;
-		goto out1;
-	}
+	dir = d_inode(parent);
 
+	dentry = simple_start_creating(parent, name);
+	if (IS_ERR(dentry)) {
+		iput(inode);
+		goto out;
+	}
 	inode->i_ino = get_next_ino();
 	inode->i_mode = mode;
-	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+	simple_inode_init_ts(inode);
 	inode->i_private = data;
-	if (is_dir) {
+	if (S_ISDIR(mode)) {
 		inode->i_op = &simple_dir_inode_operations;
 		inode->i_fop = &simple_dir_operations;
 		inc_nlink(inode);
 		inc_nlink(dir);
+	} else if (S_ISLNK(mode)) {
+		inode->i_op = iops ? iops : &simple_symlink_inode_operations;
+		inode->i_link = data;
 	} else {
 		inode->i_fop = fops;
 	}
-	d_instantiate(dentry, inode);
-	dget(dentry);
-	mutex_unlock(&dir->i_mutex);
-	return dentry;
+	d_make_persistent(dentry, inode);
+	simple_done_creating(dentry);
+	return dentry; // borrowed
 
-out1:
-	dput(dentry);
-	dentry = ERR_PTR(error);
 out:
-	mutex_unlock(&dir->i_mutex);
-	simple_release_fs(&mount, &mount_count);
+	if (pinned)
+		simple_release_fs(&mount, &mount_count);
 	return dentry;
 }
+
+/**
+ * securityfs_create_file - create a file in the securityfs filesystem
+ *
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have
+ * @parent: a pointer to the parent dentry for this file.  This should be a
+ *          directory dentry if set.  If this parameter is %NULL, then the
+ *          file will be created in the root of the securityfs filesystem.
+ * @data: a pointer to something that the caller will want to get to later
+ *        on.  The inode.i_private pointer will point to this value on
+ *        the open() call.
+ * @fops: a pointer to a struct file_operations that should be used for
+ *        this file.
+ *
+ * This function creates a file in securityfs with the given @name.
+ *
+ * This function returns a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the securityfs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here).  If an error occurs, the function will return
+ * the error value (via ERR_PTR).
+ *
+ * If securityfs is not enabled in the kernel, the value %-ENODEV is
+ * returned.
+ */
+struct dentry *securityfs_create_file(const char *name, umode_t mode,
+				      struct dentry *parent, void *data,
+				      const struct file_operations *fops)
+{
+	return securityfs_create_dentry(name, mode, parent, data, fops, NULL);
+}
 EXPORT_SYMBOL_GPL(securityfs_create_file);
 
 /**
@@ -161,22 +214,73 @@ EXPORT_SYMBOL_GPL(securityfs_create_file);
  * This function returns a pointer to a dentry if it succeeds.  This
  * pointer must be passed to the securityfs_remove() function when the file is
  * to be removed (no automatic cleanup happens if your module is unloaded,
- * you are responsible here).  If an error occurs, %NULL will be returned.
+ * you are responsible here).  If an error occurs, the function will return
+ * the error value (via ERR_PTR).
  *
  * If securityfs is not enabled in the kernel, the value %-ENODEV is
- * returned.  It is not wise to check for this value, but rather, check for
- * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
- * code.
+ * returned.
  */
 struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
 {
-	return securityfs_create_file(name,
-				      S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
-				      parent, NULL, NULL);
+	return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(securityfs_create_dir);
 
 /**
+ * securityfs_create_symlink - create a symlink in the securityfs filesystem
+ *
+ * @name: a pointer to a string containing the name of the symlink to
+ *        create.
+ * @parent: a pointer to the parent dentry for the symlink.  This should be a
+ *          directory dentry if set.  If this parameter is %NULL, then the
+ *          directory will be created in the root of the securityfs filesystem.
+ * @target: a pointer to a string containing the name of the symlink's target.
+ *          If this parameter is %NULL, then the @iops parameter needs to be
+ *          setup to handle .readlink and .get_link inode_operations.
+ * @iops: a pointer to the struct inode_operations to use for the symlink. If
+ *        this parameter is %NULL, then the default simple_symlink_inode
+ *        operations will be used.
+ *
+ * This function creates a symlink in securityfs with the given @name.
+ *
+ * This function returns a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the securityfs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here).  If an error occurs, the function will return
+ * the error value (via ERR_PTR).
+ *
+ * If securityfs is not enabled in the kernel, the value %-ENODEV is
+ * returned.
+ */
+struct dentry *securityfs_create_symlink(const char *name,
+					 struct dentry *parent,
+					 const char *target,
+					 const struct inode_operations *iops)
+{
+	struct dentry *dent;
+	char *link = NULL;
+
+	if (target) {
+		link = kstrdup(target, GFP_KERNEL);
+		if (!link)
+			return ERR_PTR(-ENOMEM);
+	}
+	dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent,
+					link, NULL, iops);
+	if (IS_ERR(dent))
+		kfree(link);
+
+	return dent;
+}
+EXPORT_SYMBOL_GPL(securityfs_create_symlink);
+
+static void remove_one(struct dentry *victim)
+{
+	if (victim->d_parent == victim->d_sb->s_root)
+		simple_release_fs(&mount, &mount_count);
+}
+
+/**
  * securityfs_remove - removes a file or directory from the securityfs filesystem
  *
  * @dentry: a pointer to a the dentry of the file or directory to be removed.
@@ -188,49 +292,89 @@ EXPORT_SYMBOL_GPL(securityfs_create_dir);
  * This function is required to be called in order for the file to be
  * removed. No automatic cleanup of files will happen when a module is
  * removed; you are responsible here.
+ *
+ * AV: when applied to directory it will take all children out; no need to call
+ * it for descendents if ancestor is getting killed.
  */
 void securityfs_remove(struct dentry *dentry)
 {
-	struct dentry *parent;
-
-	if (!dentry || IS_ERR(dentry))
+	if (IS_ERR_OR_NULL(dentry))
 		return;
 
-	parent = dentry->d_parent;
-	if (!parent || !parent->d_inode)
-		return;
+	simple_pin_fs(&fs_type, &mount, &mount_count);
+	simple_recursive_removal(dentry, remove_one);
+	simple_release_fs(&mount, &mount_count);
+}
+EXPORT_SYMBOL_GPL(securityfs_remove);
+
+#ifdef CONFIG_SECURITY
+#include <linux/spinlock.h>
+
+static struct dentry *lsm_dentry;
+
+static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
+			loff_t *ppos)
+{
+	int i;
+	static char *str;
+	static size_t len;
+	static DEFINE_SPINLOCK(lock);
+
+	/* NOTE: we never free or modify the string once it is set */
 
-	mutex_lock(&parent->d_inode->i_mutex);
-	if (positive(dentry)) {
-		if (dentry->d_inode) {
-			if (S_ISDIR(dentry->d_inode->i_mode))
-				simple_rmdir(parent->d_inode, dentry);
-			else
-				simple_unlink(parent->d_inode, dentry);
-			dput(dentry);
+	if (unlikely(!str || !len)) {
+		char *str_tmp;
+		size_t len_tmp = 0;
+
+		for (i = 0; i < lsm_active_cnt; i++)
+			/* the '+ 1' accounts for either a comma or a NUL */
+			len_tmp += strlen(lsm_idlist[i]->name) + 1;
+
+		str_tmp = kmalloc(len_tmp, GFP_KERNEL);
+		if (!str_tmp)
+			return -ENOMEM;
+		str_tmp[0] = '\0';
+
+		for (i = 0; i < lsm_active_cnt; i++) {
+			if (i > 0)
+				strcat(str_tmp, ",");
+			strcat(str_tmp, lsm_idlist[i]->name);
 		}
+
+		spin_lock(&lock);
+		if (!str) {
+			str = str_tmp;
+			len = len_tmp - 1;
+		} else
+			kfree(str_tmp);
+		spin_unlock(&lock);
 	}
-	mutex_unlock(&parent->d_inode->i_mutex);
-	simple_release_fs(&mount, &mount_count);
+
+	return simple_read_from_buffer(buf, count, ppos, str, len);
 }
-EXPORT_SYMBOL_GPL(securityfs_remove);
 
-static struct kobject *security_kobj;
+static const struct file_operations lsm_ops = {
+	.read = lsm_read,
+	.llseek = generic_file_llseek,
+};
+#endif
 
-static int __init securityfs_init(void)
+int __init securityfs_init(void)
 {
 	int retval;
 
-	security_kobj = kobject_create_and_add("security", kernel_kobj);
-	if (!security_kobj)
-		return -EINVAL;
+	retval = sysfs_create_mount_point(kernel_kobj, "security");
+	if (retval)
+		return retval;
 
 	retval = register_filesystem(&fs_type);
-	if (retval)
-		kobject_put(security_kobj);
-	return retval;
+	if (retval) {
+		sysfs_remove_mount_point(kernel_kobj, "security");
+		return retval;
+	}
+#ifdef CONFIG_SECURITY
+	lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL,
+						&lsm_ops);
+#endif
+	return 0;
 }
-
-core_initcall(securityfs_init);
-MODULE_LICENSE("GPL");
-