security/inode.c

Source file repositories/reference/linux-study-clean/security/inode.c

File Facts

System
Linux kernel
Corpus path
security/inode.c
Extension
.c
Size
11594 bytes
Lines
381
Domain
Core OS
Bucket
Security And Isolation
Inferred role
Core OS: operation-table or driver-model contract
Status
pattern implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

* @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/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 error value (via ERR_PTR).
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.
 */
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;
	struct inode *dir, *inode;
	int error;
	bool pinned = false;

	if (!(mode & S_IFMT))
		mode = (mode & S_IALLUGO) | S_IFREG;

	pr_debug("securityfs: creating file '%s'\n",name);

	if (!parent) {
		error = simple_pin_fs(&fs_type, &mount, &mount_count);
		if (error)
			return ERR_PTR(error);
		pinned = true;
		parent = mount->mnt_root;
	}

	inode = new_inode(parent->d_sb);
	if (unlikely(!inode)) {
		dentry = ERR_PTR(-ENOMEM);
		goto out;
	}

	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;
	simple_inode_init_ts(inode);
	inode->i_private = data;
	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_make_persistent(dentry, inode);
	simple_done_creating(dentry);
	return dentry; // borrowed

out:
	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

Annotation

Implementation Notes