[linux-block.git] / fs / fs_context.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Provide a way to create a superblock configuration context within the kernel
 * that allows a superblock to be set up prior to mounting.
 *
 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/magic.h>
#include <linux/security.h>
#include <linux/mnt_namespace.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <net/net_namespace.h>
#include <asm/sections.h>
#include "mount.h"
#include "internal.h"

enum legacy_fs_param {
	LEGACY_FS_UNSET_PARAMS,
	LEGACY_FS_MONOLITHIC_PARAMS,
	LEGACY_FS_INDIVIDUAL_PARAMS,
};

struct legacy_fs_context {
	char			*legacy_data;	/* Data page for legacy filesystems */
	size_t			data_size;
	enum legacy_fs_param	param_type;
};

static int legacy_init_fs_context(struct fs_context *fc);

static const struct constant_table common_set_sb_flag[] = {
	{ "dirsync",	SB_DIRSYNC },
	{ "lazytime",	SB_LAZYTIME },
	{ "mand",	SB_MANDLOCK },
	{ "posixacl",	SB_POSIXACL },
	{ "ro",		SB_RDONLY },
	{ "sync",	SB_SYNCHRONOUS },
	{ },
};

static const struct constant_table common_clear_sb_flag[] = {
	{ "async",	SB_SYNCHRONOUS },
	{ "nolazytime",	SB_LAZYTIME },
	{ "nomand",	SB_MANDLOCK },
	{ "rw",		SB_RDONLY },
	{ "silent",	SB_SILENT },
	{ },
};

static const char *const forbidden_sb_flag[] = {
	"bind",
	"dev",
	"exec",
	"move",
	"noatime",
	"nodev",
	"nodiratime",
	"noexec",
	"norelatime",
	"nostrictatime",
	"nosuid",
	"private",
	"rec",
	"relatime",
	"remount",
	"shared",
	"slave",
	"strictatime",
	"suid",
	"unbindable",
};

/*
 * Check for a common mount option that manipulates s_flags.
 */
static int vfs_parse_sb_flag(struct fs_context *fc, const char *key)
{
	unsigned int token;
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++)
		if (strcmp(key, forbidden_sb_flag[i]) == 0)
			return -EINVAL;

	token = lookup_constant(common_set_sb_flag, key, 0);
	if (token) {
		fc->sb_flags |= token;
		fc->sb_flags_mask |= token;
		return 0;
	}

	token = lookup_constant(common_clear_sb_flag, key, 0);
	if (token) {
		fc->sb_flags &= ~token;
		fc->sb_flags_mask |= token;
		return 0;
	}

	return -ENOPARAM;
}

/**
 * vfs_parse_fs_param - Add a single parameter to a superblock config
 * @fc: The filesystem context to modify
 * @param: The parameter
 *
 * A single mount option in string form is applied to the filesystem context
 * being set up.  Certain standard options (for example "ro") are translated
 * into flag bits without going to the filesystem.  The active security module
 * is allowed to observe and poach options.  Any other options are passed over
 * to the filesystem to parse.
 *
 * This may be called multiple times for a context.
 *
 * Returns 0 on success and a negative error code on failure.  In the event of
 * failure, supplementary error information may have been set.
 */
int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
{
	int ret;

	if (!param->key)
		return invalf(fc, "Unnamed parameter\n");

	ret = vfs_parse_sb_flag(fc, param->key);
	if (ret != -ENOPARAM)
		return ret;

	ret = security_fs_context_parse_param(fc, param);
	if (ret != -ENOPARAM)
		/* Param belongs to the LSM or is disallowed by the LSM; so
		 * don't pass to the FS.
		 */
		return ret;

	if (fc->ops->parse_param) {
		ret = fc->ops->parse_param(fc, param);
		if (ret != -ENOPARAM)
			return ret;
	}

	/* If the filesystem doesn't take any arguments, give it the
	 * default handling of source.
	 */
	if (strcmp(param->key, "source") == 0) {
		if (param->type != fs_value_is_string)
			return invalf(fc, "VFS: Non-string source");
		if (fc->source)
			return invalf(fc, "VFS: Multiple sources");
		fc->source = param->string;
		param->string = NULL;
		return 0;
	}

	return invalf(fc, "%s: Unknown parameter '%s'",
		      fc->fs_type->name, param->key);
}
EXPORT_SYMBOL(vfs_parse_fs_param);

/**
 * vfs_parse_fs_string - Convenience function to just parse a string.
 */
int vfs_parse_fs_string(struct fs_context *fc, const char *key,
			const char *value, size_t v_size)
{
	int ret;

	struct fs_parameter param = {
		.key	= key,
		.type	= fs_value_is_flag,
		.size	= v_size,
	};

	if (value) {
		param.string = kmemdup_nul(value, v_size, GFP_KERNEL);
		if (!param.string)
			return -ENOMEM;
		param.type = fs_value_is_string;
	}

	ret = vfs_parse_fs_param(fc, &param);
	kfree(param.string);
	return ret;
}
EXPORT_SYMBOL(vfs_parse_fs_string);

/**
 * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data
 * @ctx: The superblock configuration to fill in.
 * @data: The data to parse
 *
 * Parse a blob of data that's in key[=val][,key[=val]]* form.  This can be
 * called from the ->monolithic_mount_data() fs_context operation.
 *
 * Returns 0 on success or the error returned by the ->parse_option() fs_context
 * operation on failure.
 */
int generic_parse_monolithic(struct fs_context *fc, void *data)
{
	char *options = data, *key;
	int ret = 0;

	if (!options)
		return 0;

	ret = security_sb_eat_lsm_opts(options, &fc->security);
	if (ret)
		return ret;

	while ((key = strsep(&options, ",")) != NULL) {
		if (*key) {
			size_t v_len = 0;
			char *value = strchr(key, '=');

			if (value) {
				if (value == key)
					continue;
				*value++ = 0;
				v_len = strlen(value);
			}
			ret = vfs_parse_fs_string(fc, key, value, v_len);
			if (ret < 0)
				break;
		}
	}

	return ret;
}
EXPORT_SYMBOL(generic_parse_monolithic);

/**
 * alloc_fs_context - Create a filesystem context.
 * @fs_type: The filesystem type.
 * @reference: The dentry from which this one derives (or NULL)
 * @sb_flags: Filesystem/superblock flags (SB_*)
 * @sb_flags_mask: Applicable members of @sb_flags
 * @purpose: The purpose that this configuration shall be used for.
 *
 * Open a filesystem and create a mount context.  The mount context is
 * initialised with the supplied flags and, if a submount/automount from
 * another superblock (referred to by @reference) is supplied, may have
 * parameters such as namespaces copied across from that superblock.
 */
static struct fs_context *alloc_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)
{
	int (*init_fs_context)(struct fs_context *);
	struct fs_context *fc;
	int ret = -ENOMEM;

	fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
	if (!fc)
		return ERR_PTR(-ENOMEM);

	fc->purpose	= purpose;
	fc->sb_flags	= sb_flags;
	fc->sb_flags_mask = sb_flags_mask;
	fc->fs_type	= get_filesystem(fs_type);
	fc->cred	= get_current_cred();
	fc->net_ns	= get_net(current->nsproxy->net_ns);

	mutex_init(&fc->uapi_mutex);

	switch (purpose) {
	case FS_CONTEXT_FOR_MOUNT:
		fc->user_ns = get_user_ns(fc->cred->user_ns);
		break;
	case FS_CONTEXT_FOR_SUBMOUNT:
		fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
		break;
	case FS_CONTEXT_FOR_RECONFIGURE:
		atomic_inc(&reference->d_sb->s_active);
		fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
		fc->root = dget(reference);
		break;
	}

	/* TODO: Make all filesystems support this unconditionally */
	init_fs_context = fc->fs_type->init_fs_context;
	if (!init_fs_context)
		init_fs_context = legacy_init_fs_context;

	ret = init_fs_context(fc);
	if (ret < 0)
		goto err_fc;
	fc->need_free = true;
	return fc;

err_fc:
	put_fs_context(fc);
	return ERR_PTR(ret);
}

struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
					unsigned int sb_flags)
{
	return alloc_fs_context(fs_type, NULL, sb_flags, 0,
					FS_CONTEXT_FOR_MOUNT);
}
EXPORT_SYMBOL(fs_context_for_mount);

struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
					unsigned int sb_flags,
					unsigned int sb_flags_mask)
{
	return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags,
				sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE);
}
EXPORT_SYMBOL(fs_context_for_reconfigure);

struct fs_context *fs_context_for_submount(struct file_system_type *type,
					   struct dentry *reference)
{
	return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT);
}
EXPORT_SYMBOL(fs_context_for_submount);

void fc_drop_locked(struct fs_context *fc)
{
	struct super_block *sb = fc->root->d_sb;
	dput(fc->root);
	fc->root = NULL;
	deactivate_locked_super(sb);
}

static void legacy_fs_context_free(struct fs_context *fc);

/**
 * vfs_dup_fc_config: Duplicate a filesystem context.
 * @src_fc: The context to copy.
 */
struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
{
	struct fs_context *fc;
	int ret;

	if (!src_fc->ops->dup)
		return ERR_PTR(-EOPNOTSUPP);

	fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
	if (!fc)
		return ERR_PTR(-ENOMEM);

	mutex_init(&fc->uapi_mutex);

	fc->fs_private	= NULL;
	fc->s_fs_info	= NULL;
	fc->source	= NULL;
	fc->security	= NULL;
	get_filesystem(fc->fs_type);
	get_net(fc->net_ns);
	get_user_ns(fc->user_ns);
	get_cred(fc->cred);
	if (fc->log)
		refcount_inc(&fc->log->usage);

	/* Can't call put until we've called ->dup */
	ret = fc->ops->dup(fc, src_fc);
	if (ret < 0)
		goto err_fc;

	ret = security_fs_context_dup(fc, src_fc);
	if (ret < 0)
		goto err_fc;
	return fc;

err_fc:
	put_fs_context(fc);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL(vfs_dup_fs_context);

/**
 * logfc - Log a message to a filesystem context
 * @fc: The filesystem context to log to.
 * @fmt: The format of the buffer.
 */
void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...)
{
	va_list va;
	struct va_format vaf = {.fmt = fmt, .va = &va};

	va_start(va, fmt);
	if (!log) {
		switch (level) {
		case 'w':
			printk(KERN_WARNING "%s%s%pV\n", prefix ? prefix : "",
						prefix ? ": " : "", &vaf);
			break;
		case 'e':
			printk(KERN_ERR "%s%s%pV\n", prefix ? prefix : "",
						prefix ? ": " : "", &vaf);
			break;
		default:
			printk(KERN_NOTICE "%s%s%pV\n", prefix ? prefix : "",
						prefix ? ": " : "", &vaf);
			break;
		}
	} else {
		unsigned int logsize = ARRAY_SIZE(log->buffer);
		u8 index;
		char *q = kasprintf(GFP_KERNEL, "%c %s%s%pV\n", level,
						prefix ? prefix : "",
						prefix ? ": " : "", &vaf);

		index = log->head & (logsize - 1);
		BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) ||
			     sizeof(log->tail) != sizeof(u8));
		if ((u8)(log->head - log->tail) == logsize) {
			/* The buffer is full, discard the oldest message */
			if (log->need_free & (1 << index))
				kfree(log->buffer[index]);
			log->tail++;
		}

		log->buffer[index] = q ? q : "OOM: Can't store error string";
		if (q)
			log->need_free |= 1 << index;
		else
			log->need_free &= ~(1 << index);
		log->head++;
	}
	va_end(va);
}
EXPORT_SYMBOL(logfc);

/*
 * Free a logging structure.
 */
static void put_fc_log(struct fs_context *fc)
{
	struct fc_log *log = fc->log;
	int i;

	if (log) {
		if (refcount_dec_and_test(&log->usage)) {
			fc->log = NULL;
			for (i = 0; i <= 7; i++)
				if (log->need_free & (1 << i))
					kfree(log->buffer[i]);
			kfree(log);
		}
	}
}

/**
 * put_fs_context - Dispose of a superblock configuration context.
 * @fc: The context to dispose of.
 */
void put_fs_context(struct fs_context *fc)
{
	struct super_block *sb;

	if (fc->root) {
		sb = fc->root->d_sb;
		dput(fc->root);
		fc->root = NULL;
		deactivate_super(sb);
	}

	if (fc->need_free && fc->ops && fc->ops->free)
		fc->ops->free(fc);

	security_free_mnt_opts(&fc->security);
	put_net(fc->net_ns);
	put_user_ns(fc->user_ns);
	put_cred(fc->cred);
	put_fc_log(fc);
	put_filesystem(fc->fs_type);
	kfree(fc->source);
	kfree(fc);
}
EXPORT_SYMBOL(put_fs_context);

/*
 * Free the config for a filesystem that doesn't support fs_context.
 */
static void legacy_fs_context_free(struct fs_context *fc)
{
	struct legacy_fs_context *ctx = fc->fs_private;

	if (ctx) {
		if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS)
			kfree(ctx->legacy_data);
		kfree(ctx);
	}
}

/*
 * Duplicate a legacy config.
 */
static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
{
	struct legacy_fs_context *ctx;
	struct legacy_fs_context *src_ctx = src_fc->fs_private;

	ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL);
	if (!ctx)
		return -ENOMEM;

	if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) {
		ctx->legacy_data = kmemdup(src_ctx->legacy_data,
					   src_ctx->data_size, GFP_KERNEL);
		if (!ctx->legacy_data) {
			kfree(ctx);
			return -ENOMEM;
		}
	}

	fc->fs_private = ctx;
	return 0;
}

/*
 * Add a parameter to a legacy config.  We build up a comma-separated list of
 * options.
 */
static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
	struct legacy_fs_context *ctx = fc->fs_private;
	unsigned int size = ctx->data_size;
	size_t len = 0;

	if (strcmp(param->key, "source") == 0) {
		if (param->type != fs_value_is_string)
			return invalf(fc, "VFS: Legacy: Non-string source");
		if (fc->source)
			return invalf(fc, "VFS: Legacy: Multiple sources");
		fc->source = param->string;
		param->string = NULL;
		return 0;
	}

	if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS)
		return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options");

	switch (param->type) {
	case fs_value_is_string:
		len = 1 + param->size;
		/* Fall through */
	case fs_value_is_flag:
		len += strlen(param->key);
		break;
	default:
		return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported",
			      param->key);
	}

	if (len > PAGE_SIZE - 2 - size)
		return invalf(fc, "VFS: Legacy: Cumulative options too large");
	if (strchr(param->key, ',') ||
	    (param->type == fs_value_is_string &&
	     memchr(param->string, ',', param->size)))
		return invalf(fc, "VFS: Legacy: Option '%s' contained comma",
			      param->key);
	if (!ctx->legacy_data) {
		ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
		if (!ctx->legacy_data)
			return -ENOMEM;
	}

	ctx->legacy_data[size++] = ',';
	len = strlen(param->key);
	memcpy(ctx->legacy_data + size, param->key, len);
	size += len;
	if (param->type == fs_value_is_string) {
		ctx->legacy_data[size++] = '=';
		memcpy(ctx->legacy_data + size, param->string, param->size);
		size += param->size;
	}
	ctx->legacy_data[size] = '\0';
	ctx->data_size = size;
	ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS;
	return 0;
}

/*
 * Add monolithic mount data.
 */
static int legacy_parse_monolithic(struct fs_context *fc, void *data)
{
	struct legacy_fs_context *ctx = fc->fs_private;

	if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) {
		pr_warn("VFS: Can't mix monolithic and individual options\n");
		return -EINVAL;
	}

	ctx->legacy_data = data;
	ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS;
	if (!ctx->legacy_data)
		return 0;

	if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA)
		return 0;
	return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security);
}

/*
 * Get a mountable root with the legacy mount command.
 */
static int legacy_get_tree(struct fs_context *fc)
{
	struct legacy_fs_context *ctx = fc->fs_private;
	struct super_block *sb;
	struct dentry *root;

	root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
				      fc->source, ctx->legacy_data);
	if (IS_ERR(root))
		return PTR_ERR(root);

	sb = root->d_sb;
	BUG_ON(!sb);

	fc->root = root;
	return 0;
}

/*
 * Handle remount.
 */
static int legacy_reconfigure(struct fs_context *fc)
{
	struct legacy_fs_context *ctx = fc->fs_private;
	struct super_block *sb = fc->root->d_sb;

	if (!sb->s_op->remount_fs)
		return 0;

	return sb->s_op->remount_fs(sb, &fc->sb_flags,
				    ctx ? ctx->legacy_data : NULL);
}

const struct fs_context_operations legacy_fs_context_ops = {
	.free			= legacy_fs_context_free,
	.dup			= legacy_fs_context_dup,
	.parse_param		= legacy_parse_param,
	.parse_monolithic	= legacy_parse_monolithic,
	.get_tree		= legacy_get_tree,
	.reconfigure		= legacy_reconfigure,
};

/*
 * Initialise a legacy context for a filesystem that doesn't support
 * fs_context.
 */
static int legacy_init_fs_context(struct fs_context *fc)
{
	fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL);
	if (!fc->fs_private)
		return -ENOMEM;
	fc->ops = &legacy_fs_context_ops;
	return 0;
}

int parse_monolithic_mount_data(struct fs_context *fc, void *data)
{
	int (*monolithic_mount_data)(struct fs_context *, void *);

	monolithic_mount_data = fc->ops->parse_monolithic;
	if (!monolithic_mount_data)
		monolithic_mount_data = generic_parse_monolithic;

	return monolithic_mount_data(fc, data);
}

/*
 * Clean up a context after performing an action on it and put it into a state
 * from where it can be used to reconfigure a superblock.
 *
 * Note that here we do only the parts that can't fail; the rest is in
 * finish_clean_context() below and in between those fs_context is marked
 * FS_CONTEXT_AWAITING_RECONF.  The reason for splitup is that after
 * successful mount or remount we need to report success to userland.
 * Trying to do full reinit (for the sake of possible subsequent remount)
 * and failing to allocate memory would've put us into a nasty situation.
 * So here we only discard the old state and reinitialization is left
 * until we actually try to reconfigure.
 */
void vfs_clean_context(struct fs_context *fc)
{
	if (fc->need_free && fc->ops && fc->ops->free)
		fc->ops->free(fc);
	fc->need_free = false;
	fc->fs_private = NULL;
	fc->s_fs_info = NULL;
	fc->sb_flags = 0;
	security_free_mnt_opts(&fc->security);
	kfree(fc->source);
	fc->source = NULL;

	fc->purpose = FS_CONTEXT_FOR_RECONFIGURE;
	fc->phase = FS_CONTEXT_AWAITING_RECONF;
}

int finish_clean_context(struct fs_context *fc)
{
	int error;

	if (fc->phase != FS_CONTEXT_AWAITING_RECONF)
		return 0;

	if (fc->fs_type->init_fs_context)
		error = fc->fs_type->init_fs_context(fc);
	else
		error = legacy_init_fs_context(fc);
	if (unlikely(error)) {
		fc->phase = FS_CONTEXT_FAILED;
		return error;
	}
	fc->need_free = true;
	fc->phase = FS_CONTEXT_RECONF_PARAMS;
	return 0;
}
Commit	Line	Data
b4d0d230	1	// SPDX-License-Identifier: GPL-2.0-or-later
9bc61ab1 DH	2	/* Provide a way to create a superblock configuration context within the kernel
	3	* that allows a superblock to be set up prior to mounting.
	4	*
	5	* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
	6	* Written by David Howells (dhowells@redhat.com)
9bc61ab1 DH	7	*/
	8
	9	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
007ec26c	10	#include <linux/module.h>
9bc61ab1	11	#include <linux/fs_context.h>
3e1aeb00	12	#include <linux/fs_parser.h>
9bc61ab1 DH	13	#include <linux/fs.h>
	14	#include <linux/mount.h>
	15	#include <linux/nsproxy.h>
	16	#include <linux/slab.h>
	17	#include <linux/magic.h>
	18	#include <linux/security.h>
	19	#include <linux/mnt_namespace.h>
	20	#include <linux/pid_namespace.h>
	21	#include <linux/user_namespace.h>
	22	#include <net/net_namespace.h>
007ec26c	23	#include <asm/sections.h>
9bc61ab1 DH	24	#include "mount.h"
	25	#include "internal.h"
	26
3e1aeb00 DH	27	enum legacy_fs_param {
	28	LEGACY_FS_UNSET_PARAMS,
	29	LEGACY_FS_MONOLITHIC_PARAMS,
	30	LEGACY_FS_INDIVIDUAL_PARAMS,
	31	};
	32
9bc61ab1 DH	33	struct legacy_fs_context {
	34	char legacy_data; / Data page for legacy filesystems */
	35	size_t data_size;
3e1aeb00	36	enum legacy_fs_param param_type;
9bc61ab1 DH	37	};
	38
	39	static int legacy_init_fs_context(struct fs_context *fc);
	40
3e1aeb00 DH	41	static const struct constant_table common_set_sb_flag[] = {
	42	{ "dirsync", SB_DIRSYNC },
	43	{ "lazytime", SB_LAZYTIME },
	44	{ "mand", SB_MANDLOCK },
	45	{ "posixacl", SB_POSIXACL },
	46	{ "ro", SB_RDONLY },
	47	{ "sync", SB_SYNCHRONOUS },
34264ae3	48	{ },
3e1aeb00 DH	49	};
	50
	51	static const struct constant_table common_clear_sb_flag[] = {
	52	{ "async", SB_SYNCHRONOUS },
	53	{ "nolazytime", SB_LAZYTIME },
	54	{ "nomand", SB_MANDLOCK },
	55	{ "rw", SB_RDONLY },
	56	{ "silent", SB_SILENT },
34264ae3	57	{ },
3e1aeb00 DH	58	};
	59
	60	static const char *const forbidden_sb_flag[] = {
	61	"bind",
	62	"dev",
	63	"exec",
	64	"move",
	65	"noatime",
	66	"nodev",
	67	"nodiratime",
	68	"noexec",
	69	"norelatime",
	70	"nostrictatime",
	71	"nosuid",
	72	"private",
	73	"rec",
	74	"relatime",
	75	"remount",
	76	"shared",
	77	"slave",
	78	"strictatime",
	79	"suid",
	80	"unbindable",
	81	};
	82
	83	/*
	84	* Check for a common mount option that manipulates s_flags.
	85	*/
	86	static int vfs_parse_sb_flag(struct fs_context fc, const char key)
	87	{
	88	unsigned int token;
	89	unsigned int i;
	90
	91	for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++)
	92	if (strcmp(key, forbidden_sb_flag[i]) == 0)
	93	return -EINVAL;
	94
	95	token = lookup_constant(common_set_sb_flag, key, 0);
	96	if (token) {
	97	fc->sb_flags \|= token;
	98	fc->sb_flags_mask \|= token;
	99	return 0;
	100	}
	101
	102	token = lookup_constant(common_clear_sb_flag, key, 0);
	103	if (token) {
	104	fc->sb_flags &= ~token;
	105	fc->sb_flags_mask \|= token;
	106	return 0;
	107	}
	108
	109	return -ENOPARAM;
	110	}
	111
	112	/**
	113	* vfs_parse_fs_param - Add a single parameter to a superblock config
	114	* @fc: The filesystem context to modify
	115	* @param: The parameter
	116	*
	117	* A single mount option in string form is applied to the filesystem context
	118	* being set up. Certain standard options (for example "ro") are translated
	119	* into flag bits without going to the filesystem. The active security module
	120	* is allowed to observe and poach options. Any other options are passed over
	121	* to the filesystem to parse.
122	*
123	* This may be called multiple times for a context.
124	*
125	* Returns 0 on success and a negative error code on failure. In the event of
126	* failure, supplementary error information may have been set.
127	*/
128	int vfs_parse_fs_param(struct fs_context fc, struct fs_parameter param)
129	{
130	int ret;
131
132	if (!param->key)
133	return invalf(fc, "Unnamed parameter\n");
134
135	ret = vfs_parse_sb_flag(fc, param->key);
136	if (ret != -ENOPARAM)
137	return ret;
138
139	ret = security_fs_context_parse_param(fc, param);
140	if (ret != -ENOPARAM)
141	/* Param belongs to the LSM or is disallowed by the LSM; so
142	* don't pass to the FS.
143	*/
144	return ret;
145
146	if (fc->ops->parse_param) {
147	ret = fc->ops->parse_param(fc, param);
148	if (ret != -ENOPARAM)
149	return ret;
150	}
151
152	/* If the filesystem doesn't take any arguments, give it the
153	* default handling of source.
154	*/
155	if (strcmp(param->key, "source") == 0) {
156	if (param->type != fs_value_is_string)
157	return invalf(fc, "VFS: Non-string source");
158	if (fc->source)
159	return invalf(fc, "VFS: Multiple sources");
160	fc->source = param->string;
161	param->string = NULL;
162	return 0;
163	}
164
165	return invalf(fc, "%s: Unknown parameter '%s'",
166	fc->fs_type->name, param->key);
167	}
168	EXPORT_SYMBOL(vfs_parse_fs_param);
169
170	/**
171	* vfs_parse_fs_string - Convenience function to just parse a string.
172	*/
173	int vfs_parse_fs_string(struct fs_context fc, const char key,
174	const char *value, size_t v_size)
175	{
176	int ret;
177
178	struct fs_parameter param = {
179	.key = key,
0f89589a	180	.type = fs_value_is_flag,
3e1aeb00 DH	181	.size = v_size,
	182	};
	183
0f89589a	184	if (value) {
3e1aeb00 DH	185	param.string = kmemdup_nul(value, v_size, GFP_KERNEL);
	186	if (!param.string)
	187	return -ENOMEM;
0f89589a	188	param.type = fs_value_is_string;
3e1aeb00 DH	189	}
	190
	191	ret = vfs_parse_fs_param(fc, &param);
	192	kfree(param.string);
	193	return ret;
	194	}
	195	EXPORT_SYMBOL(vfs_parse_fs_string);
	196
	197	/**
	198	* generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data
	199	* @ctx: The superblock configuration to fill in.
	200	* @data: The data to parse
	201	*
	202	* Parse a blob of data that's in key[=val][,key[=val]]* form. This can be
	203	* called from the ->monolithic_mount_data() fs_context operation.
	204	*
	205	* Returns 0 on success or the error returned by the ->parse_option() fs_context
	206	* operation on failure.
	207	*/
	208	int generic_parse_monolithic(struct fs_context fc, void data)
	209	{
	210	char options = data, key;
	211	int ret = 0;
	212
	213	if (!options)
	214	return 0;
	215
	216	ret = security_sb_eat_lsm_opts(options, &fc->security);
	217	if (ret)
	218	return ret;
	219
	220	while ((key = strsep(&options, ",")) != NULL) {
	221	if (*key) {
	222	size_t v_len = 0;
	223	char *value = strchr(key, '=');
	224
	225	if (value) {
	226	if (value == key)
	227	continue;
	228	*value++ = 0;
	229	v_len = strlen(value);
	230	}
	231	ret = vfs_parse_fs_string(fc, key, value, v_len);
	232	if (ret < 0)
	233	break;
	234	}
	235	}
	236
	237	return ret;
	238	}
	239	EXPORT_SYMBOL(generic_parse_monolithic);
	240
9bc61ab1 DH	241	/**
	242	* alloc_fs_context - Create a filesystem context.
	243	* @fs_type: The filesystem type.
	244	* @reference: The dentry from which this one derives (or NULL)
	245	* @sb_flags: Filesystem/superblock flags (SB_*)
	246	* @sb_flags_mask: Applicable members of @sb_flags
	247	* @purpose: The purpose that this configuration shall be used for.
	248	*
	249	* Open a filesystem and create a mount context. The mount context is
	250	* initialised with the supplied flags and, if a submount/automount from
	251	* another superblock (referred to by @reference) is supplied, may have
	252	* parameters such as namespaces copied across from that superblock.
	253	*/
	254	static struct fs_context alloc_fs_context(struct file_system_type fs_type,
	255	struct dentry *reference,
	256	unsigned int sb_flags,
	257	unsigned int sb_flags_mask,
	258	enum fs_context_purpose purpose)
	259	{
f3a09c92	260	int (init_fs_context)(struct fs_context );
9bc61ab1 DH	261	struct fs_context *fc;
	262	int ret = -ENOMEM;
	263
	264	fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);
	265	if (!fc)
	266	return ERR_PTR(-ENOMEM);
	267
	268	fc->purpose = purpose;
	269	fc->sb_flags = sb_flags;
	270	fc->sb_flags_mask = sb_flags_mask;
	271	fc->fs_type = get_filesystem(fs_type);
	272	fc->cred = get_current_cred();
	273	fc->net_ns = get_net(current->nsproxy->net_ns);
	274
24dcb3d9 DH	275	mutex_init(&fc->uapi_mutex);
24dcb3d9 DH	276
9bc61ab1 DH	277	switch (purpose) {
	278	case FS_CONTEXT_FOR_MOUNT:
	279	fc->user_ns = get_user_ns(fc->cred->user_ns);
	280	break;
e1a91586 AV	281	case FS_CONTEXT_FOR_SUBMOUNT:
	282	fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
	283	break;
8d0347f6	284	case FS_CONTEXT_FOR_RECONFIGURE:
8d0347f6	285	atomic_inc(&reference->d_sb->s_active);
1dd9bc08	286	fc->user_ns = get_user_ns(reference->d_sb->s_user_ns);
8d0347f6 DH	287	fc->root = dget(reference);
8d0347f6 DH	288	break;
9bc61ab1 DH	289	}
9bc61ab1 DH	290
f3a09c92 AV	291	/* TODO: Make all filesystems support this unconditionally */
	292	init_fs_context = fc->fs_type->init_fs_context;
	293	if (!init_fs_context)
	294	init_fs_context = legacy_init_fs_context;
	295
	296	ret = init_fs_context(fc);
9bc61ab1 DH	297	if (ret < 0)
	298	goto err_fc;
	299	fc->need_free = true;
	300	return fc;
	301
	302	err_fc:
	303	put_fs_context(fc);
	304	return ERR_PTR(ret);
	305	}
	306
	307	struct fs_context fs_context_for_mount(struct file_system_type fs_type,
	308	unsigned int sb_flags)
	309	{
	310	return alloc_fs_context(fs_type, NULL, sb_flags, 0,
	311	FS_CONTEXT_FOR_MOUNT);
	312	}
	313	EXPORT_SYMBOL(fs_context_for_mount);
	314
8d0347f6 DH	315	struct fs_context fs_context_for_reconfigure(struct dentry dentry,
	316	unsigned int sb_flags,
	317	unsigned int sb_flags_mask)
	318	{
	319	return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags,
	320	sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE);
	321	}
	322	EXPORT_SYMBOL(fs_context_for_reconfigure);
	323
e1a91586 AV	324	struct fs_context fs_context_for_submount(struct file_system_type type,
	325	struct dentry *reference)
	326	{
	327	return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT);
	328	}
	329	EXPORT_SYMBOL(fs_context_for_submount);
	330
c9ce29ed AV	331	void fc_drop_locked(struct fs_context *fc)
	332	{
	333	struct super_block *sb = fc->root->d_sb;
	334	dput(fc->root);
	335	fc->root = NULL;
	336	deactivate_locked_super(sb);
	337	}
	338
9bc61ab1	339	static void legacy_fs_context_free(struct fs_context *fc);
8d0347f6	340
0b52075e AV	341	/**
	342	* vfs_dup_fc_config: Duplicate a filesystem context.
	343	* @src_fc: The context to copy.
	344	*/
	345	struct fs_context vfs_dup_fs_context(struct fs_context src_fc)
	346	{
	347	struct fs_context *fc;
	348	int ret;
	349
	350	if (!src_fc->ops->dup)
	351	return ERR_PTR(-EOPNOTSUPP);
	352
	353	fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL);
	354	if (!fc)
	355	return ERR_PTR(-ENOMEM);
	356
24dcb3d9 DH	357	mutex_init(&fc->uapi_mutex);
24dcb3d9 DH	358
0b52075e AV	359	fc->fs_private = NULL;
	360	fc->s_fs_info = NULL;
	361	fc->source = NULL;
	362	fc->security = NULL;
	363	get_filesystem(fc->fs_type);
	364	get_net(fc->net_ns);
	365	get_user_ns(fc->user_ns);
	366	get_cred(fc->cred);
007ec26c DH	367	if (fc->log)
007ec26c DH	368	refcount_inc(&fc->log->usage);
0b52075e AV	369
	370	/* Can't call put until we've called ->dup */
	371	ret = fc->ops->dup(fc, src_fc);
	372	if (ret < 0)
	373	goto err_fc;
	374
	375	ret = security_fs_context_dup(fc, src_fc);
	376	if (ret < 0)
	377	goto err_fc;
	378	return fc;
	379
	380	err_fc:
	381	put_fs_context(fc);
	382	return ERR_PTR(ret);
	383	}
	384	EXPORT_SYMBOL(vfs_dup_fs_context);
	385
e7582e16 DH	386	/**
	387	* logfc - Log a message to a filesystem context
	388	* @fc: The filesystem context to log to.
	389	* @fmt: The format of the buffer.
	390	*/
9f09f649	391	void logfc(struct fc_log log, const char prefix, char level, const char *fmt, ...)
e7582e16 DH	392	{
e7582e16 DH	393	va_list va;
9f09f649	394	struct va_format vaf = {.fmt = fmt, .va = &va};
e7582e16 DH	395
e7582e16 DH	396	va_start(va, fmt);
007ec26c	397	if (!log) {
9f09f649	398	switch (level) {
007ec26c	399	case 'w':
9f09f649 AV	400	printk(KERN_WARNING "%s%s%pV\n", prefix ? prefix : "",
9f09f649 AV	401	prefix ? ": " : "", &vaf);
007ec26c DH	402	break;
007ec26c DH	403	case 'e':
9f09f649 AV	404	printk(KERN_ERR "%s%s%pV\n", prefix ? prefix : "",
9f09f649 AV	405	prefix ? ": " : "", &vaf);
007ec26c DH	406	break;
007ec26c DH	407	default:
9f09f649 AV	408	printk(KERN_NOTICE "%s%s%pV\n", prefix ? prefix : "",
9f09f649 AV	409	prefix ? ": " : "", &vaf);
007ec26c DH	410	break;
007ec26c DH	411	}
007ec26c DH	412	} else {
	413	unsigned int logsize = ARRAY_SIZE(log->buffer);
	414	u8 index;
9f09f649 AV	415	char *q = kasprintf(GFP_KERNEL, "%c %s%s%pV\n", level,
	416	prefix ? prefix : "",
	417	prefix ? ": " : "", &vaf);
007ec26c DH	418
	419	index = log->head & (logsize - 1);
	420	BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) \|\|
	421	sizeof(log->tail) != sizeof(u8));
	422	if ((u8)(log->head - log->tail) == logsize) {
	423	/* The buffer is full, discard the oldest message */
	424	if (log->need_free & (1 << index))
	425	kfree(log->buffer[index]);
	426	log->tail++;
	427	}
e7582e16	428
9f09f649 AV	429	log->buffer[index] = q ? q : "OOM: Can't store error string";
	430	if (q)
	431	log->need_free \|= 1 << index;
	432	else
	433	log->need_free &= ~(1 << index);
007ec26c DH	434	log->head++;
007ec26c DH	435	}
e7582e16 DH	436	va_end(va);
	437	}
	438	EXPORT_SYMBOL(logfc);
007ec26c DH	439
	440	/*
	441	* Free a logging structure.
	442	*/
	443	static void put_fc_log(struct fs_context *fc)
	444	{
	445	struct fc_log *log = fc->log;
	446	int i;
	447
	448	if (log) {
	449	if (refcount_dec_and_test(&log->usage)) {
	450	fc->log = NULL;
	451	for (i = 0; i <= 7; i++)
	452	if (log->need_free & (1 << i))
	453	kfree(log->buffer[i]);
	454	kfree(log);
	455	}
	456	}
	457	}
e7582e16	458
9bc61ab1 DH	459	/**
	460	* put_fs_context - Dispose of a superblock configuration context.
	461	* @fc: The context to dispose of.
	462	*/
	463	void put_fs_context(struct fs_context *fc)
	464	{
	465	struct super_block *sb;
	466
	467	if (fc->root) {
	468	sb = fc->root->d_sb;
	469	dput(fc->root);
	470	fc->root = NULL;
	471	deactivate_super(sb);
	472	}
	473
f3a09c92 AV	474	if (fc->need_free && fc->ops && fc->ops->free)
f3a09c92 AV	475	fc->ops->free(fc);
9bc61ab1 DH	476
9bc61ab1 DH	477	security_free_mnt_opts(&fc->security);
8d0347f6	478	put_net(fc->net_ns);
9bc61ab1 DH	479	put_user_ns(fc->user_ns);
9bc61ab1 DH	480	put_cred(fc->cred);
007ec26c	481	put_fc_log(fc);
9bc61ab1 DH	482	put_filesystem(fc->fs_type);
	483	kfree(fc->source);
	484	kfree(fc);
	485	}
	486	EXPORT_SYMBOL(put_fs_context);
	487
	488	/*
	489	* Free the config for a filesystem that doesn't support fs_context.
	490	*/
	491	static void legacy_fs_context_free(struct fs_context *fc)
	492	{
3e1aeb00 DH	493	struct legacy_fs_context *ctx = fc->fs_private;
	494
	495	if (ctx) {
	496	if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS)
	497	kfree(ctx->legacy_data);
	498	kfree(ctx);
	499	}
	500	}
	501
0b52075e AV	502	/*
	503	* Duplicate a legacy config.
	504	*/
	505	static int legacy_fs_context_dup(struct fs_context fc, struct fs_context src_fc)
	506	{
	507	struct legacy_fs_context *ctx;
	508	struct legacy_fs_context *src_ctx = src_fc->fs_private;
	509
	510	ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL);
	511	if (!ctx)
	512	return -ENOMEM;
	513
	514	if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) {
	515	ctx->legacy_data = kmemdup(src_ctx->legacy_data,
	516	src_ctx->data_size, GFP_KERNEL);
	517	if (!ctx->legacy_data) {
	518	kfree(ctx);
	519	return -ENOMEM;
	520	}
	521	}
	522
	523	fc->fs_private = ctx;
	524	return 0;
	525	}
	526
3e1aeb00 DH	527	/*
	528	* Add a parameter to a legacy config. We build up a comma-separated list of
	529	* options.
	530	*/
	531	static int legacy_parse_param(struct fs_context fc, struct fs_parameter param)
	532	{
	533	struct legacy_fs_context *ctx = fc->fs_private;
	534	unsigned int size = ctx->data_size;
	535	size_t len = 0;
	536
	537	if (strcmp(param->key, "source") == 0) {
	538	if (param->type != fs_value_is_string)
	539	return invalf(fc, "VFS: Legacy: Non-string source");
	540	if (fc->source)
	541	return invalf(fc, "VFS: Legacy: Multiple sources");
	542	fc->source = param->string;
	543	param->string = NULL;
	544	return 0;
	545	}
	546
3e1aeb00 DH	547	if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS)
	548	return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options");
	549
	550	switch (param->type) {
	551	case fs_value_is_string:
	552	len = 1 + param->size;
	553	/* Fall through */
	554	case fs_value_is_flag:
	555	len += strlen(param->key);
	556	break;
	557	default:
	558	return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported",
	559	param->key);
	560	}
	561
	562	if (len > PAGE_SIZE - 2 - size)
	563	return invalf(fc, "VFS: Legacy: Cumulative options too large");
	564	if (strchr(param->key, ',') \|\|
	565	(param->type == fs_value_is_string &&
	566	memchr(param->string, ',', param->size)))
	567	return invalf(fc, "VFS: Legacy: Option '%s' contained comma",
	568	param->key);
	569	if (!ctx->legacy_data) {
	570	ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
	571	if (!ctx->legacy_data)
	572	return -ENOMEM;
	573	}
	574
	575	ctx->legacy_data[size++] = ',';
	576	len = strlen(param->key);
	577	memcpy(ctx->legacy_data + size, param->key, len);
	578	size += len;
	579	if (param->type == fs_value_is_string) {
	580	ctx->legacy_data[size++] = '=';
	581	memcpy(ctx->legacy_data + size, param->string, param->size);
	582	size += param->size;
	583	}
	584	ctx->legacy_data[size] = '\0';
	585	ctx->data_size = size;
	586	ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS;
	587	return 0;
9bc61ab1 DH	588	}
	589
	590	/*
	591	* Add monolithic mount data.
	592	*/
	593	static int legacy_parse_monolithic(struct fs_context fc, void data)
	594	{
	595	struct legacy_fs_context *ctx = fc->fs_private;
3e1aeb00 DH	596
	597	if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) {
	598	pr_warn("VFS: Can't mix monolithic and individual options\n");
	599	return -EINVAL;
	600	}
	601
9bc61ab1	602	ctx->legacy_data = data;
3e1aeb00	603	ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS;
9bc61ab1 DH	604	if (!ctx->legacy_data)
9bc61ab1 DH	605	return 0;
3e1aeb00	606
9bc61ab1 DH	607	if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA)
	608	return 0;
	609	return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security);
	610	}
	611
	612	/*
	613	* Get a mountable root with the legacy mount command.
	614	*/
f3a09c92	615	static int legacy_get_tree(struct fs_context *fc)
9bc61ab1 DH	616	{
	617	struct legacy_fs_context *ctx = fc->fs_private;
	618	struct super_block *sb;
	619	struct dentry *root;
	620
	621	root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
	622	fc->source, ctx->legacy_data);
	623	if (IS_ERR(root))
	624	return PTR_ERR(root);
	625
	626	sb = root->d_sb;
	627	BUG_ON(!sb);
	628
	629	fc->root = root;
	630	return 0;
	631	}
	632
8d0347f6 DH	633	/*
	634	* Handle remount.
	635	*/
f3a09c92	636	static int legacy_reconfigure(struct fs_context *fc)
8d0347f6 DH	637	{
	638	struct legacy_fs_context *ctx = fc->fs_private;
	639	struct super_block *sb = fc->root->d_sb;
	640
	641	if (!sb->s_op->remount_fs)
	642	return 0;
	643
	644	return sb->s_op->remount_fs(sb, &fc->sb_flags,
	645	ctx ? ctx->legacy_data : NULL);
	646	}
	647
f3a09c92 AV	648	const struct fs_context_operations legacy_fs_context_ops = {
f3a09c92 AV	649	.free = legacy_fs_context_free,
0b52075e	650	.dup = legacy_fs_context_dup,
3e1aeb00	651	.parse_param = legacy_parse_param,
f3a09c92 AV	652	.parse_monolithic = legacy_parse_monolithic,
	653	.get_tree = legacy_get_tree,
	654	.reconfigure = legacy_reconfigure,
	655	};
	656
9bc61ab1 DH	657	/*
	658	* Initialise a legacy context for a filesystem that doesn't support
	659	* fs_context.
	660	*/
	661	static int legacy_init_fs_context(struct fs_context *fc)
	662	{
	663	fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL);
	664	if (!fc->fs_private)
	665	return -ENOMEM;
f3a09c92	666	fc->ops = &legacy_fs_context_ops;
9bc61ab1 DH	667	return 0;
	668	}
	669
	670	int parse_monolithic_mount_data(struct fs_context fc, void data)
	671	{
f3a09c92	672	int (monolithic_mount_data)(struct fs_context , void *);
3e1aeb00	673
f3a09c92	674	monolithic_mount_data = fc->ops->parse_monolithic;
3e1aeb00 DH	675	if (!monolithic_mount_data)
	676	monolithic_mount_data = generic_parse_monolithic;
	677
f3a09c92	678	return monolithic_mount_data(fc, data);
9bc61ab1	679	}
ecdab150 DH	680
	681	/*
	682	* Clean up a context after performing an action on it and put it into a state
	683	* from where it can be used to reconfigure a superblock.
	684	*
	685	* Note that here we do only the parts that can't fail; the rest is in
	686	* finish_clean_context() below and in between those fs_context is marked
	687	* FS_CONTEXT_AWAITING_RECONF. The reason for splitup is that after
	688	* successful mount or remount we need to report success to userland.
	689	* Trying to do full reinit (for the sake of possible subsequent remount)
	690	* and failing to allocate memory would've put us into a nasty situation.
	691	* So here we only discard the old state and reinitialization is left
	692	* until we actually try to reconfigure.
	693	*/
	694	void vfs_clean_context(struct fs_context *fc)
	695	{
	696	if (fc->need_free && fc->ops && fc->ops->free)
	697	fc->ops->free(fc);
	698	fc->need_free = false;
	699	fc->fs_private = NULL;
	700	fc->s_fs_info = NULL;
	701	fc->sb_flags = 0;
	702	security_free_mnt_opts(&fc->security);
ecdab150 DH	703	kfree(fc->source);
	704	fc->source = NULL;
	705
	706	fc->purpose = FS_CONTEXT_FOR_RECONFIGURE;
	707	fc->phase = FS_CONTEXT_AWAITING_RECONF;
	708	}
	709
	710	int finish_clean_context(struct fs_context *fc)
	711	{
	712	int error;
	713
	714	if (fc->phase != FS_CONTEXT_AWAITING_RECONF)
	715	return 0;
	716
	717	if (fc->fs_type->init_fs_context)
	718	error = fc->fs_type->init_fs_context(fc);
	719	else
	720	error = legacy_init_fs_context(fc);
	721	if (unlikely(error)) {
	722	fc->phase = FS_CONTEXT_FAILED;
	723	return error;
	724	}
	725	fc->need_free = true;
	726	fc->phase = FS_CONTEXT_RECONF_PARAMS;
	727	return 0;
	728	}