1 /* Filesystem superblock creation and reconfiguration context. 2 * 3 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells ([email protected]) 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/errno.h> 17 #include <linux/security.h> 18 19 struct cred; 20 struct dentry; 21 struct file_operations; 22 struct file_system_type; 23 struct mnt_namespace; 24 struct net; 25 struct pid_namespace; 26 struct super_block; 27 struct user_namespace; 28 struct vfsmount; 29 struct path; 30 31 enum fs_context_purpose { 32 FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */ 33 FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */ 34 FS_CONTEXT_FOR_RECONFIGURE, /* Superblock reconfiguration (remount) */ 35 }; 36 37 /* 38 * Type of parameter value. 39 */ 40 enum fs_value_type { 41 fs_value_is_undefined, 42 fs_value_is_flag, /* Value not given a value */ 43 fs_value_is_string, /* Value is a string */ 44 fs_value_is_blob, /* Value is a binary blob */ 45 fs_value_is_filename, /* Value is a filename* + dirfd */ 46 fs_value_is_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */ 47 fs_value_is_file, /* Value is a file* */ 48 }; 49 50 /* 51 * Configuration parameter. 52 */ 53 struct fs_parameter { 54 const char *key; /* Parameter name */ 55 enum fs_value_type type:8; /* The type of value here */ 56 union { 57 char *string; 58 void *blob; 59 struct filename *name; 60 struct file *file; 61 }; 62 size_t size; 63 int dirfd; 64 }; 65 66 /* 67 * Filesystem context for holding the parameters used in the creation or 68 * reconfiguration of a superblock. 69 * 70 * Superblock creation fills in ->root whereas reconfiguration begins with this 71 * already set. 72 * 73 * See Documentation/filesystems/mounting.txt 74 */ 75 struct fs_context { 76 const struct fs_context_operations *ops; 77 struct file_system_type *fs_type; 78 void *fs_private; /* The filesystem's context */ 79 struct dentry *root; /* The root and superblock */ 80 struct user_namespace *user_ns; /* The user namespace for this mount */ 81 struct net *net_ns; /* The network namespace for this mount */ 82 const struct cred *cred; /* The mounter's credentials */ 83 const char *source; /* The source name (eg. dev path) */ 84 const char *subtype; /* The subtype to set on the superblock */ 85 void *security; /* Linux S&M options */ 86 void *s_fs_info; /* Proposed s_fs_info */ 87 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */ 88 unsigned int sb_flags_mask; /* Superblock flags that were changed */ 89 unsigned int lsm_flags; /* Information flags from the fs to the LSM */ 90 enum fs_context_purpose purpose:8; 91 bool need_free:1; /* Need to call ops->free() */ 92 bool global:1; /* Goes into &init_user_ns */ 93 }; 94 95 struct fs_context_operations { 96 void (*free)(struct fs_context *fc); 97 int (*dup)(struct fs_context *fc, struct fs_context *src_fc); 98 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param); 99 int (*parse_monolithic)(struct fs_context *fc, void *data); 100 int (*get_tree)(struct fs_context *fc); 101 int (*reconfigure)(struct fs_context *fc); 102 }; 103 104 /* 105 * fs_context manipulation functions. 106 */ 107 extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, 108 unsigned int sb_flags); 109 extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, 110 unsigned int sb_flags, 111 unsigned int sb_flags_mask); 112 extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type, 113 struct dentry *reference); 114 115 extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc); 116 extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param); 117 extern int vfs_parse_fs_string(struct fs_context *fc, const char *key, 118 const char *value, size_t v_size); 119 extern int generic_parse_monolithic(struct fs_context *fc, void *data); 120 extern int vfs_get_tree(struct fs_context *fc); 121 extern void put_fs_context(struct fs_context *fc); 122 123 /* 124 * sget() wrapper to be called from the ->get_tree() op. 125 */ 126 enum vfs_get_super_keying { 127 vfs_get_single_super, /* Only one such superblock may exist */ 128 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */ 129 vfs_get_independent_super, /* Multiple independent superblocks may exist */ 130 }; 131 extern int vfs_get_super(struct fs_context *fc, 132 enum vfs_get_super_keying keying, 133 int (*fill_super)(struct super_block *sb, 134 struct fs_context *fc)); 135 136 extern const struct file_operations fscontext_fops; 137 138 #ifdef CONFIG_PRINTK 139 extern __attribute__((format(printf, 2, 3))) 140 void logfc(struct fs_context *fc, const char *fmt, ...); 141 #else 142 static inline __attribute__((format(printf, 2, 3))) 143 void logfc(struct fs_context *fc, const char *fmt, ...) 144 { 145 } 146 #endif 147 148 /** 149 * infof - Store supplementary informational message 150 * @fc: The context in which to log the informational message 151 * @fmt: The format string 152 * 153 * Store the supplementary informational message for the process if the process 154 * has enabled the facility. 155 */ 156 #define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); }) 157 158 /** 159 * warnf - Store supplementary warning message 160 * @fc: The context in which to log the error message 161 * @fmt: The format string 162 * 163 * Store the supplementary warning message for the process if the process has 164 * enabled the facility. 165 */ 166 #define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); }) 167 168 /** 169 * errorf - Store supplementary error message 170 * @fc: The context in which to log the error message 171 * @fmt: The format string 172 * 173 * Store the supplementary error message for the process if the process has 174 * enabled the facility. 175 */ 176 #define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); }) 177 178 /** 179 * invalf - Store supplementary invalid argument error message 180 * @fc: The context in which to log the error message 181 * @fmt: The format string 182 * 183 * Store the supplementary error message for the process if the process has 184 * enabled the facility and return -EINVAL. 185 */ 186 #define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; }) 187 188 #endif /* _LINUX_FS_CONTEXT_H */ 189