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Diffstat (limited to 'include/linux/fs_context.h')
| -rw-r--r-- | include/linux/fs_context.h | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h new file mode 100644 index 000000000..c13e99cbb --- /dev/null +++ b/include/linux/fs_context.h @@ -0,0 +1,237 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Filesystem superblock creation and reconfiguration context. + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#ifndef _LINUX_FS_CONTEXT_H +#define _LINUX_FS_CONTEXT_H + +#include <linux/kernel.h> +#include <linux/refcount.h> +#include <linux/errno.h> +#include <linux/security.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_MOUNT, /* New superblock for explicit mount */ + FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */ + FS_CONTEXT_FOR_RECONFIGURE, /* Superblock reconfiguration (remount) */ +}; + +/* + * 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_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; +}; + +struct p_log { + const char *prefix; + struct fc_log *log; +}; + +/* + * 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/mount_api.rst + */ +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 */ + void *sget_key; + 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 p_log log; /* Logging buffer */ + const char *source; /* The source name (eg. dev path) */ + void *security; /* LSM options */ + 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 s_iflags; /* OR'd with sb->s_iflags */ + enum fs_context_purpose purpose:8; + enum fs_context_phase phase:8; /* The phase the context is in */ + bool need_free:1; /* Need to call ops->free() */ + bool global:1; /* Goes into &init_user_ns */ + bool oldapi:1; /* Coming from mount(2) */ + bool exclusive:1; /* create new superblock, reject existing one */ +}; + +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); + int (*get_tree)(struct fs_context *fc); + int (*reconfigure)(struct fs_context *fc); +}; + +/* + * fs_context manipulation functions. + */ +extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, + unsigned int sb_flags); +extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, + unsigned int sb_flags, + unsigned int sb_flags_mask); +extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type, + struct dentry *reference); + +extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc); +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); +int vfs_parse_monolithic_sep(struct fs_context *fc, void *data, + char *(*sep)(char **)); +extern int generic_parse_monolithic(struct fs_context *fc, void *data); +extern int vfs_get_tree(struct fs_context *fc); +extern void put_fs_context(struct fs_context *fc); +extern int vfs_parse_fs_param_source(struct fs_context *fc, + struct fs_parameter *param); +extern void fc_drop_locked(struct fs_context *fc); +int reconfigure_single(struct super_block *s, + int flags, void *data); + +extern int get_tree_nodev(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc)); +extern int get_tree_single(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc)); +extern int get_tree_keyed(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc), + void *key); + +int setup_bdev_super(struct super_block *sb, int sb_flags, + struct fs_context *fc); +extern int get_tree_bdev(struct fs_context *fc, + 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, 4, 5))) +void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...); + +#define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \ + l, fmt, ## __VA_ARGS__) +#define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \ + l, fmt, ## __VA_ARGS__) +/** + * 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__) +#define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__) +#define infofc(p, fmt, ...) __plog((&(fc)->log), '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__) +#define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__) +#define warnfc(fc, fmt, ...) __plog((&(fc)->log), '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__) +#define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__) +#define errorfc(fc, fmt, ...) __plog((&(fc)->log), '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) +#define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL) +#define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL) + +#endif /* _LINUX_FS_CONTEXT_H */ |