1 files changed, 215 insertions, 0 deletions
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
new file mode 100644
index 000000000000..bb584db982ff
--- /dev/null
+++ b/include/linux/fs_context.h
@@ -0,0 +1,215 @@
+/* Filesystem superblock creation and reconfiguration context.
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_FS_CONTEXT_H
+#define _LINUX_FS_CONTEXT_H
+
+#include <linux/kernel.h>
+#include <linux/refcount.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+
+struct cred;
+struct dentry;
+struct file_operations;
+struct file_system_type;
+struct mnt_namespace;
+struct net;
+struct pid_namespace;
+struct super_block;
+struct user_namespace;
+struct vfsmount;
+struct path;
+
+enum fs_context_purpose {
+	FS_CONTEXT_FOR_USER_MOUNT,	/* New superblock for user-specified mount */
+	FS_CONTEXT_FOR_KERNEL_MOUNT,	/* New superblock for kernel-internal mount */
+	FS_CONTEXT_FOR_SUBMOUNT,	/* New superblock for automatic submount */
+	FS_CONTEXT_FOR_ROOT_MOUNT,	/* New superblock for internal root mount */
+	FS_CONTEXT_FOR_RECONFIGURE,	/* Superblock reconfiguration (remount) */
+	FS_CONTEXT_FOR_UMOUNT,		/* Reconfiguration to R/O for unmount */
+	FS_CONTEXT_FOR_EMERGENCY_RO,	/* Emergency reconfiguration to R/O */
+};
+
+/*
+ * Userspace usage phase for fsopen/fspick.
+ */
+enum fs_context_phase {
+	FS_CONTEXT_CREATE_PARAMS,	/* Loading params for sb creation */
+	FS_CONTEXT_CREATING,		/* A superblock is being created */
+	FS_CONTEXT_AWAITING_MOUNT,	/* Superblock created, awaiting fsmount() */
+	FS_CONTEXT_AWAITING_RECONF,	/* Awaiting initialisation for reconfiguration */
+	FS_CONTEXT_RECONF_PARAMS,	/* Loading params for reconfiguration */
+	FS_CONTEXT_RECONFIGURING,	/* Reconfiguring the superblock */
+	FS_CONTEXT_FAILED,		/* Failed to correctly transition a context */
+};
+
+/*
+ * Type of parameter value.
+ */
+enum fs_value_type {
+	fs_value_is_undefined,
+	fs_value_is_flag,		/* Value not given a value */
+	fs_value_is_string,		/* Value is a string */
+	fs_value_is_blob,		/* Value is a binary blob */
+	fs_value_is_filename,		/* Value is a filename* + dirfd */
+	fs_value_is_filename_empty,	/* Value is a filename* + dirfd + AT_EMPTY_PATH */
+	fs_value_is_file,		/* Value is a file* */
+};
+
+/*
+ * Configuration parameter.
+ */
+struct fs_parameter {
+	const char		*key;		/* Parameter name */
+	enum fs_value_type	type:8;		/* The type of value here */
+	union {
+		char		*string;
+		void		*blob;
+		struct filename	*name;
+		struct file	*file;
+	};
+	size_t	size;
+	int	dirfd;
+};
+
+/*
+ * Filesystem context for holding the parameters used in the creation or
+ * reconfiguration of a superblock.
+ *
+ * Superblock creation fills in ->root whereas reconfiguration begins with this
+ * already set.
+ *
+ * See Documentation/filesystems/mounting.txt
+ */
+struct fs_context {
+	const struct fs_context_operations *ops;
+	struct mutex		uapi_mutex;	/* Userspace access mutex */
+	struct file_system_type	*fs_type;
+	void			*fs_private;	/* The filesystem's context */
+	struct dentry		*root;		/* The root and superblock */
+	struct user_namespace	*user_ns;	/* The user namespace for this mount */
+	struct net		*net_ns;	/* The network namespace for this mount */
+	const struct cred	*cred;		/* The mounter's credentials */
+	struct fc_log		*log;		/* Logging buffer */
+	char			*source;	/* The source name (eg. dev path) */
+	char			*subtype;	/* The subtype to set on the superblock */
+	void			*security;	/* The LSM context */
+	void			*s_fs_info;	/* Proposed s_fs_info */
+	unsigned int		sb_flags;	/* Proposed superblock flags (SB_*) */
+	unsigned int		sb_flags_mask;	/* Superblock flags that were changed */
+	unsigned int		lsm_flags;	/* Information flags from the fs to the LSM */
+	enum fs_context_purpose	purpose:8;
+	enum fs_context_phase	phase:8;	/* The phase the context is in */
+	bool			sloppy:1;	/* T if unrecognised options are okay */
+	bool			silent:1;	/* T if "o silent" specified */
+	bool			need_free:1;	/* Need to call ops->free() */
+};
+
+struct fs_context_operations {
+	void (*free)(struct fs_context *fc);
+	int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
+	int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
+	int (*parse_monolithic)(struct fs_context *fc, void *data, size_t data_size);
+	int (*validate)(struct fs_context *fc);
+	int (*get_tree)(struct fs_context *fc);
+	int (*reconfigure)(struct fs_context *fc);
+};
+
+/*
+ * fs_context manipulation functions.
+ */
+extern struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type,
+					     struct dentry *reference,
+					     unsigned int sb_flags,
+					     unsigned int sb_flags_mask,
+					     enum fs_context_purpose purpose);
+extern struct fs_context *vfs_dup_fs_context(struct fs_context *src,
+					     enum fs_context_purpose purpose);
+extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
+extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
+			       const char *value, size_t v_size);
+extern int generic_parse_monolithic(struct fs_context *fc, void *data, size_t data_size);
+extern int vfs_get_tree(struct fs_context *fc);
+extern void put_fs_context(struct fs_context *fc);
+
+/*
+ * sget() wrapper to be called from the ->get_tree() op.
+ */
+enum vfs_get_super_keying {
+	vfs_get_single_super,	/* Only one such superblock may exist */
+	vfs_get_keyed_super,	/* Superblocks with different s_fs_info keys may exist */
+	vfs_get_independent_super, /* Multiple independent superblocks may exist */
+};
+extern int vfs_get_super(struct fs_context *fc,
+			 enum vfs_get_super_keying keying,
+			 int (*fill_super)(struct super_block *sb,
+					   struct fs_context *fc));
+
+extern const struct file_operations fscontext_fops;
+
+/*
+ * Mount error, warning and informational message logging.  This structure is
+ * shareable between a mount and a subordinate mount.
+ */
+struct fc_log {
+	refcount_t	usage;
+	u8		head;		/* Insertion index in buffer[] */
+	u8		tail;		/* Removal index in buffer[] */
+	u8		need_free;	/* Mask of kfree'able items in buffer[] */
+	struct module	*owner;		/* Owner module for strings that don't then need freeing */
+	char		*buffer[8];
+};
+
+extern __attribute__((format(printf, 2, 3)))
+void logfc(struct fs_context *fc, const char *fmt, ...);
+
+/**
+ * infof - Store supplementary informational message
+ * @fc: The context in which to log the informational message
+ * @fmt: The format string
+ *
+ * Store the supplementary informational message for the process if the process
+ * has enabled the facility.
+ */
+#define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); })
+
+/**
+ * warnf - Store supplementary warning message
+ * @fc: The context in which to log the error message
+ * @fmt: The format string
+ *
+ * Store the supplementary warning message for the process if the process has
+ * enabled the facility.
+ */
+#define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); })
+
+/**
+ * errorf - Store supplementary error message
+ * @fc: The context in which to log the error message
+ * @fmt: The format string
+ *
+ * Store the supplementary error message for the process if the process has
+ * enabled the facility.
+ */
+#define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); })
+
+/**
+ * invalf - Store supplementary invalid argument error message
+ * @fc: The context in which to log the error message
+ * @fmt: The format string
+ *
+ * Store the supplementary error message for the process if the process has
+ * enabled the facility and return -EINVAL.
+ */
+#define invalf(fc, fmt, ...) ({	errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; })
+
+#endif /* _LINUX_FS_CONTEXT_H */