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/refcount.h> 17 #include <linux/errno.h> 18 #include <linux/security.h> 19 #include <linux/mutex.h> 20 21 struct cred; 22 struct dentry; 23 struct file_operations; 24 struct file_system_type; 25 struct mnt_namespace; 26 struct net; 27 struct pid_namespace; 28 struct super_block; 29 struct user_namespace; 30 struct vfsmount; 31 struct path; 32 33 enum 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 */ 42 enum 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 */ 55 enum 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_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */ 62 fs_value_is_file, /* Value is a file* */ 63 }; 64 65 /* 66 * Configuration parameter. 67 */ 68 struct fs_parameter { 69 const char *key; /* Parameter name */ 70 enum fs_value_type type:8; /* The type of value here */ 71 union { 72 char *string; 73 void *blob; 74 struct filename *name; 75 struct file *file; 76 }; 77 size_t size; 78 int dirfd; 79 }; 80 81 /* 82 * Filesystem context for holding the parameters used in the creation or 83 * reconfiguration of a superblock. 84 * 85 * Superblock creation fills in ->root whereas reconfiguration begins with this 86 * already set. 87 * 88 * See Documentation/filesystems/mounting.txt 89 */ 90 struct fs_context { 91 const struct fs_context_operations *ops; 92 struct mutex uapi_mutex; /* Userspace access mutex */ 93 struct file_system_type *fs_type; 94 void *fs_private; /* The filesystem's context */ 95 struct dentry *root; /* The root and superblock */ 96 struct user_namespace *user_ns; /* The user namespace for this mount */ 97 struct net *net_ns; /* The network namespace for this mount */ 98 const struct cred *cred; /* The mounter's credentials */ 99 struct fc_log *log; /* Logging buffer */ 100 const char *source; /* The source name (eg. dev path) */ 101 const char *subtype; /* The subtype to set on the superblock */ 102 void *security; /* Linux S&M options */ 103 void *s_fs_info; /* Proposed s_fs_info */ 104 unsigned int sb_flags; /* Proposed superblock flags (SB_*) */ 105 unsigned int sb_flags_mask; /* Superblock flags that were changed */ 106 unsigned int s_iflags; /* OR'd with sb->s_iflags */ 107 unsigned int lsm_flags; /* Information flags from the fs to the LSM */ 108 enum fs_context_purpose purpose:8; 109 enum fs_context_phase phase:8; /* The phase the context is in */ 110 bool need_free:1; /* Need to call ops->free() */ 111 bool global:1; /* Goes into &init_user_ns */ 112 }; 113 114 struct fs_context_operations { 115 void (*free)(struct fs_context *fc); 116 int (*dup)(struct fs_context *fc, struct fs_context *src_fc); 117 int (*parse_param)(struct fs_context *fc, struct fs_parameter *param); 118 int (*parse_monolithic)(struct fs_context *fc, void *data); 119 int (*get_tree)(struct fs_context *fc); 120 int (*reconfigure)(struct fs_context *fc); 121 }; 122 123 /* 124 * fs_context manipulation functions. 125 */ 126 extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, 127 unsigned int sb_flags); 128 extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, 129 unsigned int sb_flags, 130 unsigned int sb_flags_mask); 131 extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type, 132 struct dentry *reference); 133 134 extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc); 135 extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param); 136 extern int vfs_parse_fs_string(struct fs_context *fc, const char *key, 137 const char *value, size_t v_size); 138 extern int generic_parse_monolithic(struct fs_context *fc, void *data); 139 extern int vfs_get_tree(struct fs_context *fc); 140 extern void put_fs_context(struct fs_context *fc); 141 142 /* 143 * sget() wrapper to be called from the ->get_tree() op. 144 */ 145 enum vfs_get_super_keying { 146 vfs_get_single_super, /* Only one such superblock may exist */ 147 vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */ 148 vfs_get_independent_super, /* Multiple independent superblocks may exist */ 149 }; 150 extern int vfs_get_super(struct fs_context *fc, 151 enum vfs_get_super_keying keying, 152 int (*fill_super)(struct super_block *sb, 153 struct fs_context *fc)); 154 extern int get_tree_nodev(struct fs_context *fc, 155 int (*fill_super)(struct super_block *sb, 156 struct fs_context *fc)); 157 extern int get_tree_single(struct fs_context *fc, 158 int (*fill_super)(struct super_block *sb, 159 struct fs_context *fc)); 160 161 extern const struct file_operations fscontext_fops; 162 163 /* 164 * Mount error, warning and informational message logging. This structure is 165 * shareable between a mount and a subordinate mount. 166 */ 167 struct fc_log { 168 refcount_t usage; 169 u8 head; /* Insertion index in buffer[] */ 170 u8 tail; /* Removal index in buffer[] */ 171 u8 need_free; /* Mask of kfree'able items in buffer[] */ 172 struct module *owner; /* Owner module for strings that don't then need freeing */ 173 char *buffer[8]; 174 }; 175 176 extern __attribute__((format(printf, 2, 3))) 177 void logfc(struct fs_context *fc, const char *fmt, ...); 178 179 /** 180 * infof - Store supplementary informational message 181 * @fc: The context in which to log the informational message 182 * @fmt: The format string 183 * 184 * Store the supplementary informational message for the process if the process 185 * has enabled the facility. 186 */ 187 #define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); }) 188 189 /** 190 * warnf - Store supplementary warning message 191 * @fc: The context in which to log the error message 192 * @fmt: The format string 193 * 194 * Store the supplementary warning message for the process if the process has 195 * enabled the facility. 196 */ 197 #define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); }) 198 199 /** 200 * errorf - Store supplementary error message 201 * @fc: The context in which to log the error message 202 * @fmt: The format string 203 * 204 * Store the supplementary error message for the process if the process has 205 * enabled the facility. 206 */ 207 #define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); }) 208 209 /** 210 * invalf - Store supplementary invalid argument error message 211 * @fc: The context in which to log the error message 212 * @fmt: The format string 213 * 214 * Store the supplementary error message for the process if the process has 215 * enabled the facility and return -EINVAL. 216 */ 217 #define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; }) 218 219 #endif /* _LINUX_FS_CONTEXT_H */ 220