LXR linux/include/linux/fs

   1/* Filesystem superblock creation and reconfiguration context.
   2 *
   3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11
  12#ifndef _LINUX_FS_CONTEXT_H
  13#define _LINUX_FS_CONTEXT_H
  14
  15#include <linux/kernel.h>
  16#include <linux/refcount.h>
  17#include <linux/errno.h>
  18#include <linux/security.h>
  19#include <linux/mutex.h>
  20
  21struct cred;
  22struct dentry;
  23struct file_operations;
  24struct file_system_type;
  25struct mnt_namespace;
  26struct net;
  27struct pid_namespace;
  28struct super_block;
  29struct user_namespace;
  30struct vfsmount;
  31struct path;
  32
  33enum fs_context_purpose {
  34        FS_CONTEXT_FOR_MOUNT,           /* New superblock for explicit mount */
  35        FS_CONTEXT_FOR_SUBMOUNT,        /* New superblock for automatic submount */
  36        FS_CONTEXT_FOR_RECONFIGURE,     /* Superblock reconfiguration (remount) */
  37};
  38
  39/*
  40 * Userspace usage phase for fsopen/fspick.
  41 */
  42enum fs_context_phase {
  43        FS_CONTEXT_CREATE_PARAMS,       /* Loading params for sb creation */
  44        FS_CONTEXT_CREATING,            /* A superblock is being created */
  45        FS_CONTEXT_AWAITING_MOUNT,      /* Superblock created, awaiting fsmount() */
  46        FS_CONTEXT_AWAITING_RECONF,     /* Awaiting initialisation for reconfiguration */
  47        FS_CONTEXT_RECONF_PARAMS,       /* Loading params for reconfiguration */
  48        FS_CONTEXT_RECONFIGURING,       /* Reconfiguring the superblock */
  49        FS_CONTEXT_FAILED,              /* Failed to correctly transition a context */
  50};
  51
  52/*
  53 * Type of parameter value.
  54 */
  55enum fs_value_type {
  56        fs_value_is_undefined,
  57        fs_value_is_flag,               /* Value not given a value */
  58        fs_value_is_string,             /* Value is a string */
  59        fs_value_is_blob,               /* Value is a binary blob */
  60        fs_value_is_filename,           /* Value is a filename* + dirfd */
  61        fs_value_is_file,               /* Value is a file* */
  62};
  63
  64/*
  65 * Configuration parameter.
  66 */
  67struct fs_parameter {
  68        const char              *key;           /* Parameter name */
  69        enum fs_value_type      type:8;         /* The type of value here */
  70        union {
  71                char            *string;
  72                void            *blob;
  73                struct filename *name;
  74                struct file     *file;
  75        };
  76        size_t  size;
  77        int     dirfd;
  78};
  79
  80struct p_log {
  81        const char *prefix;
  82        struct fc_log *log;
  83};
  84
  85/*
  86 * Filesystem context for holding the parameters used in the creation or
  87 * reconfiguration of a superblock.
  88 *
  89 * Superblock creation fills in ->root whereas reconfiguration begins with this
  90 * already set.
  91 *
  92 * See Documentation/filesystems/mounting.txt
  93 */
  94struct fs_context {
  95        const struct fs_context_operations *ops;
  96        struct mutex            uapi_mutex;     /* Userspace access mutex */
  97        struct file_system_type *fs_type;
  98        void                    *fs_private;    /* The filesystem's context */
  99        void                    *sget_key;
 100        struct dentry           *root;          /* The root and superblock */
 101        struct user_namespace   *user_ns;       /* The user namespace for this mount */
 102        struct net              *net_ns;        /* The network namespace for this mount */
 103        const struct cred       *cred;          /* The mounter's credentials */
 104        struct p_log            log;            /* Logging buffer */
 105        const char              *source;        /* The source name (eg. dev path) */
 106        void                    *security;      /* Linux S&M options */
 107        void                    *s_fs_info;     /* Proposed s_fs_info */
 108        unsigned int            sb_flags;       /* Proposed superblock flags (SB_*) */
 109        unsigned int            sb_flags_mask;  /* Superblock flags that were changed */
 110        unsigned int            s_iflags;       /* OR'd with sb->s_iflags */
 111        unsigned int            lsm_flags;      /* Information flags from the fs to the LSM */
 112        enum fs_context_purpose purpose:8;
 113        enum fs_context_phase   phase:8;        /* The phase the context is in */
 114        bool                    need_free:1;    /* Need to call ops->free() */
 115        bool                    global:1;       /* Goes into &init_user_ns */
 116        bool                    oldapi:1;       /* Coming from mount(2) */
 117};
 118
 119struct fs_context_operations {
 120        void (*free)(struct fs_context *fc);
 121        int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
 122        int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
 123        int (*parse_monolithic)(struct fs_context *fc, void *data);
 124        int (*get_tree)(struct fs_context *fc);
 125        int (*reconfigure)(struct fs_context *fc);
 126};
 127
 128/*
 129 * fs_context manipulation functions.
 130 */
 131extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
 132                                                unsigned int sb_flags);
 133extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
 134                                                unsigned int sb_flags,
 135                                                unsigned int sb_flags_mask);
 136extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
 137                                                struct dentry *reference);
 138
 139extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
 140extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
 141extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
 142                               const char *value, size_t v_size);
 143extern int generic_parse_monolithic(struct fs_context *fc, void *data);
 144extern int vfs_get_tree(struct fs_context *fc);
 145extern void put_fs_context(struct fs_context *fc);
 146extern int vfs_parse_fs_param_source(struct fs_context *fc,
 147                                     struct fs_parameter *param);
 148
 149/*
 150 * sget() wrappers to be called from the ->get_tree() op.
 151 */
 152enum vfs_get_super_keying {
 153        vfs_get_single_super,   /* Only one such superblock may exist */
 154        vfs_get_single_reconf_super, /* As above, but reconfigure if it exists */
 155        vfs_get_keyed_super,    /* Superblocks with different s_fs_info keys may exist */
 156        vfs_get_independent_super, /* Multiple independent superblocks may exist */
 157};
 158extern int vfs_get_super(struct fs_context *fc,
 159                         enum vfs_get_super_keying keying,
 160                         int (*fill_super)(struct super_block *sb,
 161                                           struct fs_context *fc));
 162
 163extern int get_tree_nodev(struct fs_context *fc,
 164                         int (*fill_super)(struct super_block *sb,
 165                                           struct fs_context *fc));
 166extern int get_tree_single(struct fs_context *fc,
 167                         int (*fill_super)(struct super_block *sb,
 168                                           struct fs_context *fc));
 169extern int get_tree_single_reconf(struct fs_context *fc,
 170                         int (*fill_super)(struct super_block *sb,
 171                                           struct fs_context *fc));
 172extern int get_tree_keyed(struct fs_context *fc,
 173                         int (*fill_super)(struct super_block *sb,
 174                                           struct fs_context *fc),
 175                         void *key);
 176
 177extern int get_tree_bdev(struct fs_context *fc,
 178                               int (*fill_super)(struct super_block *sb,
 179                                                 struct fs_context *fc));
 180
 181extern const struct file_operations fscontext_fops;
 182
 183/*
 184 * Mount error, warning and informational message logging.  This structure is
 185 * shareable between a mount and a subordinate mount.
 186 */
 187struct fc_log {
 188        refcount_t      usage;
 189        u8              head;           /* Insertion index in buffer[] */
 190        u8              tail;           /* Removal index in buffer[] */
 191        u8              need_free;      /* Mask of kfree'able items in buffer[] */
 192        struct module   *owner;         /* Owner module for strings that don't then need freeing */
 193        char            *buffer[8];
 194};
 195
 196extern __attribute__((format(printf, 4, 5)))
 197void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
 198
 199#define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \
 200                                        l, fmt, ## __VA_ARGS__)
 201#define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \
 202                                        l, fmt, ## __VA_ARGS__)
 203/**
 204 * infof - Store supplementary informational message
 205 * @fc: The context in which to log the informational message
 206 * @fmt: The format string
 207 *
 208 * Store the supplementary informational message for the process if the process
 209 * has enabled the facility.
 210 */
 211#define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
 212#define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__)
 213#define infofc(p, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__)
 214
 215/**
 216 * warnf - Store supplementary warning message
 217 * @fc: The context in which to log the error message
 218 * @fmt: The format string
 219 *
 220 * Store the supplementary warning message for the process if the process has
 221 * enabled the facility.
 222 */
 223#define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
 224#define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__)
 225#define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__)
 226
 227/**
 228 * errorf - Store supplementary error message
 229 * @fc: The context in which to log the error message
 230 * @fmt: The format string
 231 *
 232 * Store the supplementary error message for the process if the process has
 233 * enabled the facility.
 234 */
 235#define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
 236#define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__)
 237#define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__)
 238
 239/**
 240 * invalf - Store supplementary invalid argument error message
 241 * @fc: The context in which to log the error message
 242 * @fmt: The format string
 243 *
 244 * Store the supplementary error message for the process if the process has
 245 * enabled the facility and return -EINVAL.
 246 */
 247#define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
 248#define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL)
 249#define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL)
 250
 251#endif /* _LINUX_FS_CONTEXT_H */
 252