lkml.org 
[lkml]   [2017]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 03/14] VFS: Implement a filesystem superblock creation/configuration context [ver #6]
From
Date
Implement a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount.

The mounting procedure then becomes:

(1) Allocate new fs_context context.

(2) Configure the context.

(3) Create superblock.

(4) Mount the superblock any number of times.

(5) Destroy the context.

Rather than calling fs_type->mount(), an fs_context struct is created and
fs_type->init_fs_context() is called to set it up.
fs_type->fs_context_size says how much space should be allocated for the
config context. The fs_context struct is placed at the beginning and any
extra space is for the filesystem's use.

A set of operations has to be set by ->init_fs_context() to provide
freeing, duplication, option parsing, binary data parsing, validation,
mounting and superblock filling.

Legacy filesystems are supported by the provision of a set of legacy
fs_context operations that build up a list of mount options and then invoke
fs_type->mount() from within the fs_context ->get_tree() operation. This
allows all filesystems to be accessed using fs_context.

It should be noted that, whilst this patch adds a lot of lines of code,
there is quite a bit of duplication with existing code that can be
eliminated should all filesystems be converted over.

Signed-off-by: David Howells <dhowells@redhat.com>
---

Documentation/filesystems/mounting.txt | 7
fs/Makefile | 3
fs/fs_context.c | 526 ++++++++++++++++++++++++++++++++
fs/internal.h | 2
fs/libfs.c | 17 +
fs/namespace.c | 337 ++++++++++++++-------
fs/super.c | 294 +++++++++++++++++-
include/linux/fs.h | 16 +
include/linux/fs_context.h | 37 ++
include/linux/lsm_hooks.h | 6
include/linux/mount.h | 2
security/security.c | 4
security/selinux/hooks.c | 6
13 files changed, 1107 insertions(+), 150 deletions(-)
create mode 100644 fs/fs_context.c

diff --git a/Documentation/filesystems/mounting.txt b/Documentation/filesystems/mounting.txt
index 8c0b0351e949..ba73066c151c 100644
--- a/Documentation/filesystems/mounting.txt
+++ b/Documentation/filesystems/mounting.txt
@@ -192,7 +192,7 @@ structure is not refcounted.

VFS, security and filesystem mount options are set individually with
vfs_parse_mount_option(). Options provided by the old mount(2) system call as
-a page of data can be parsed with generic_monolithic_mount_data().
+a page of data can be parsed with generic_parse_monolithic().

When mounting, the filesystem is allowed to take data from any of the pointers
and attach it to the superblock (or whatever), provided it clears the pointer
@@ -264,7 +264,7 @@ manage the filesystem context. They are as follows:

If the filesystem (eg. NFS) needs to examine the data first and then finds
it's the standard key-val list then it may pass it off to
- generic_monolithic_mount_data().
+ generic_parse_monolithic().

(*) int (*validate)(struct fs_context *fc);

@@ -407,9 +407,10 @@ returned.
[NOTE] ->validate() could perhaps be rolled into ->get_tree() and
->remount_fs_fc().

- (*) struct vfsmount *vfs_kern_mount_fc(struct fs_context *fc);
+ (*) struct vfsmount *vfs_create_mount(struct fs_context *fc);

Create a mount given the parameters in the specified filesystem context.
+ Note that this does not attach the mount to anything.

(*) int vfs_set_fs_source(struct fs_context *fc, char *source);

diff --git a/fs/Makefile b/fs/Makefile
index 7bbaca9c67b1..ffe728cc15e1 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -11,7 +11,8 @@ obj-y := open.o read_write.o file_table.o super.o \
attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o \
- stack.o fs_struct.o statfs.o fs_pin.o nsfs.o
+ stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
+ fs_context.o

ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o block_dev.o direct-io.o mpage.o
diff --git a/fs/fs_context.c b/fs/fs_context.c
new file mode 100644
index 000000000000..a3a7ccb4323d
--- /dev/null
+++ b/fs/fs_context.c
@@ -0,0 +1,526 @@
+/* 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)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/fs_context.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/parser.h>
+#include <linux/mnt_namespace.h>
+#include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
+#include <net/net_namespace.h>
+#include "mount.h"
+
+struct legacy_fs_context {
+ struct fs_context fc;
+ char *legacy_data; /* Data page for legacy filesystems */
+ char *secdata;
+ unsigned int data_usage;
+};
+
+static const struct fs_context_operations legacy_fs_context_ops;
+
+static const match_table_t common_set_sb_flag = {
+ { SB_DIRSYNC, "dirsync" },
+ { SB_LAZYTIME, "lazytime" },
+ { SB_MANDLOCK, "mand" },
+ { SB_POSIXACL, "posixacl" },
+ { SB_RDONLY, "ro" },
+ { SB_SYNCHRONOUS, "sync" },
+ { },
+};
+
+static const match_table_t common_clear_sb_flag = {
+ { SB_LAZYTIME, "nolazytime" },
+ { SB_MANDLOCK, "nomand" },
+ { SB_RDONLY, "rw" },
+ { SB_SILENT, "silent" },
+ { SB_SYNCHRONOUS, "async" },
+ { },
+};
+
+static const match_table_t forbidden_sb_flag = {
+ { 0, "bind" },
+ { 0, "move" },
+ { 0, "private" },
+ { 0, "remount" },
+ { 0, "shared" },
+ { 0, "slave" },
+ { 0, "unbindable" },
+ { 0, "rec" },
+ { 0, "noatime" },
+ { 0, "relatime" },
+ { 0, "norelatime" },
+ { 0, "strictatime" },
+ { 0, "nostrictatime" },
+ { 0, "nodiratime" },
+ { 0, "dev" },
+ { 0, "nodev" },
+ { 0, "exec" },
+ { 0, "noexec" },
+ { 0, "suid" },
+ { 0, "nosuid" },
+ { },
+};
+
+/*
+ * Check for a common mount option that manipulates s_flags.
+ */
+static int vfs_parse_sb_flag_option(struct fs_context *fc, char *data)
+{
+ substring_t args[MAX_OPT_ARGS];
+ unsigned int token;
+
+ token = match_token(data, common_set_sb_flag, args);
+ if (token) {
+ fc->sb_flags |= token;
+ return 1;
+ }
+
+ token = match_token(data, common_clear_sb_flag, args);
+ if (token) {
+ fc->sb_flags &= ~token;
+ return 1;
+ }
+
+ token = match_token(data, forbidden_sb_flag, args);
+ if (token)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
+ * vfs_parse_mount_option - Add a single mount option to a superblock config
+ * @fc: The filesystem context to modify
+ * @p: The option to apply.
+ *
+ * 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_mount_option(struct fs_context *fc, char *p)
+{
+ int ret;
+
+ ret = vfs_parse_sb_flag_option(fc, p);
+ if (ret < 0)
+ return ret;
+ if (ret == 1)
+ return 0;
+
+ ret = security_fs_context_parse_option(fc, p);
+ if (ret < 0)
+ return ret;
+ if (ret == 1)
+ return 0;
+
+ if (fc->ops->parse_option)
+ return fc->ops->parse_option(fc, p);
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL(vfs_parse_mount_option);
+
+/**
+ * vfs_set_fs_source - Set the source/device name in a filesystem context
+ * @fc: The filesystem context to alter
+ * @source: The name of the source
+ * @slen: Length of @source string
+ */
+int vfs_set_fs_source(struct fs_context *fc, const char *source, size_t slen)
+{
+ if (fc->source)
+ return -EINVAL;
+ if (source) {
+ fc->source = kmemdup_nul(source, slen, GFP_KERNEL);
+ if (!fc->source)
+ return -ENOMEM;
+ }
+
+ if (fc->ops->parse_source)
+ return fc->ops->parse_source(fc);
+ return 0;
+}
+EXPORT_SYMBOL(vfs_set_fs_source);
+
+/**
+ * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data
+ * @mc: 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 *ctx, void *data)
+{
+ char *options = data, *p;
+ int ret;
+
+ if (!options)
+ return 0;
+
+ while ((p = strsep(&options, ",")) != NULL) {
+ if (*p) {
+ ret = vfs_parse_mount_option(ctx, p);
+ if (ret < 0)
+ return ret;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(generic_parse_monolithic);
+
+/**
+ * vfs_new_fs_context - Create a filesystem context.
+ * @fs_type: The filesystem type.
+ * @src_sb: A superblock from which this one derives (or NULL)
+ * @sb_flags: Superblock flags and op flags (such as MS_REMOUNT)
+ * @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 (@src_sb), may have parameters such as namespaces copied
+ * across from that superblock.
+ */
+struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type,
+ struct super_block *src_sb,
+ unsigned int sb_flags,
+ enum fs_context_purpose purpose)
+{
+ struct fs_context *fc;
+ size_t fc_size = fs_type->fs_context_size;
+ int ret;
+
+ BUG_ON(fs_type->init_fs_context && fc_size < sizeof(*fc));
+
+ if (!fs_type->init_fs_context)
+ fc_size = sizeof(struct legacy_fs_context);
+
+ fc = kzalloc(fc_size, GFP_KERNEL);
+ if (!fc)
+ return ERR_PTR(-ENOMEM);
+
+ fc->purpose = purpose;
+ fc->sb_flags = sb_flags;
+ fc->fs_type = get_filesystem(fs_type);
+ fc->cred = get_current_cred();
+
+ switch (purpose) {
+ case FS_CONTEXT_FOR_KERNEL_MOUNT:
+ fc->sb_flags |= SB_KERNMOUNT;
+ /* Fallthrough */
+ case FS_CONTEXT_FOR_USER_MOUNT:
+ fc->user_ns = get_user_ns(fc->cred->user_ns);
+ fc->net_ns = get_net(current->nsproxy->net_ns);
+ break;
+ case FS_CONTEXT_FOR_SUBMOUNT:
+ fc->user_ns = get_user_ns(src_sb->s_user_ns);
+ fc->net_ns = get_net(current->nsproxy->net_ns);
+ break;
+ case FS_CONTEXT_FOR_REMOUNT:
+ /* We don't pin any namespaces as the superblock's
+ * subscriptions cannot be changed at this point.
+ */
+ break;
+ }
+
+
+ /* TODO: Make all filesystems support this unconditionally */
+ if (fc->fs_type->init_fs_context) {
+ ret = fc->fs_type->init_fs_context(fc, src_sb);
+ if (ret < 0)
+ goto err_fc;
+ } else {
+ fc->ops = &legacy_fs_context_ops;
+ }
+
+ /* Do the security check last because ->init_fs_context may change the
+ * namespace subscriptions.
+ */
+ ret = security_fs_context_alloc(fc, src_sb);
+ if (ret < 0)
+ goto err_fc;
+
+ return fc;
+
+err_fc:
+ put_fs_context(fc);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(vfs_new_fs_context);
+
+/**
+ * vfs_sb_reconfig - Create a filesystem context for remount/reconfiguration
+ * @mnt: The mountpoint to open
+ * @sb_flags: Superblock flags and op flags (such as MS_REMOUNT)
+ *
+ * Open a mounted filesystem and create a filesystem context such that a
+ * remount can be effected.
+ */
+struct fs_context *vfs_sb_reconfig(struct vfsmount *mnt,
+ unsigned int sb_flags)
+{
+ return vfs_new_fs_context(mnt->mnt_sb->s_type, mnt->mnt_sb,
+ sb_flags, FS_CONTEXT_FOR_REMOUNT);
+}
+
+/**
+ * vfs_dup_fc_config: Duplicate a filesytem context.
+ * @src_fc: The context to copy.
+ */
+struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc)
+{
+ struct fs_context *fc;
+ size_t fc_size;
+ int ret;
+
+ if (!src_fc->ops->dup)
+ return ERR_PTR(-ENOTSUPP);
+
+ fc_size = src_fc->fs_type->fs_context_size;
+ if (!src_fc->fs_type->init_fs_context)
+ fc_size = sizeof(struct legacy_fs_context);
+
+ fc = kmemdup(src_fc, src_fc->fs_type->fs_context_size, GFP_KERNEL);
+ if (!fc)
+ return ERR_PTR(-ENOMEM);
+
+ 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);
+
+ /* 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);
+
+/**
+ * put_fs_context - Dispose of a superblock configuration context.
+ * @sc: 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->ops && fc->ops->free)
+ fc->ops->free(fc);
+
+ security_fs_context_free(fc);
+ if (fc->net_ns)
+ put_net(fc->net_ns);
+ put_user_ns(fc->user_ns);
+ if (fc->cred)
+ put_cred(fc->cred);
+ kfree(fc->subtype);
+ 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 = container_of(fc, struct legacy_fs_context, fc);
+
+ free_secdata(ctx->secdata);
+ kfree(ctx->legacy_data);
+}
+
+/*
+ * Duplicate a legacy config.
+ */
+static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
+{
+ struct legacy_fs_context *ctx = container_of(fc, struct legacy_fs_context, fc);
+ struct legacy_fs_context *src_ctx = container_of(src_fc, struct legacy_fs_context, fc);
+
+ ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!ctx->legacy_data)
+ return -ENOMEM;
+ memcpy(ctx->legacy_data, src_ctx->legacy_data, sizeof(PAGE_SIZE));
+ return 0;
+}
+
+/*
+ * Add an option to a legacy config. We build up a comma-separated list of
+ * options.
+ */
+static int legacy_parse_option(struct fs_context *fc, char *p)
+{
+ struct legacy_fs_context *ctx = container_of(fc, struct legacy_fs_context, fc);
+ unsigned int usage = ctx->data_usage;
+ size_t len = strlen(p);
+
+ if (len > PAGE_SIZE - 2 - usage)
+ return -EINVAL;
+ if (memchr(p, ',', len) != NULL)
+ return -EINVAL;
+ if (!ctx->legacy_data) {
+ ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!ctx->legacy_data)
+ return -ENOMEM;
+ }
+
+ ctx->legacy_data[usage++] = ',';
+ memcpy(ctx->legacy_data + usage, p, len);
+ usage += len;
+ ctx->legacy_data[usage] = '\0';
+ ctx->data_usage = usage;
+ return 0;
+}
+
+/*
+ * Add monolithic mount data.
+ */
+static int legacy_parse_monolithic(struct fs_context *fc, void *data)
+{
+ struct legacy_fs_context *ctx = container_of(fc, struct legacy_fs_context, fc);
+
+ if (ctx->data_usage != 0) {
+ pr_warn("VFS: Can't mix monolithic and individual options\n");
+ return -EINVAL;
+ }
+ if (!data)
+ return 0;
+ if (!ctx->legacy_data) {
+ ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!ctx->legacy_data)
+ return -ENOMEM;
+ }
+
+ memcpy(ctx->legacy_data, data, PAGE_SIZE);
+ ctx->data_usage = PAGE_SIZE;
+ return 0;
+}
+
+/*
+ * Use the legacy mount validation step to strip out and process security
+ * config options.
+ */
+static int legacy_validate(struct fs_context *fc)
+{
+ struct legacy_fs_context *ctx = container_of(fc, struct legacy_fs_context, fc);
+
+ if (!ctx->legacy_data || ctx->fc.fs_type->fs_flags & FS_BINARY_MOUNTDATA)
+ return 0;
+
+ ctx->secdata = alloc_secdata();
+ if (!ctx->secdata)
+ return -ENOMEM;
+
+ return security_sb_copy_data(ctx->legacy_data, ctx->secdata);
+}
+
+/*
+ * Determine the superblock subtype.
+ */
+static int legacy_set_subtype(struct fs_context *fc)
+{
+ const char *subtype = strchr(fc->fs_type->name, '.');
+
+ if (subtype) {
+ subtype++;
+ if (!subtype[0])
+ return -EINVAL;
+ } else {
+ subtype = "";
+ }
+
+ fc->subtype = kstrdup(subtype, GFP_KERNEL);
+ if (!fc->subtype)
+ return -ENOMEM;
+ return 0;
+}
+
+/*
+ * Get a mountable root with the legacy mount command.
+ */
+static int legacy_get_tree(struct fs_context *fc)
+{
+ struct legacy_fs_context *ctx = container_of(fc, struct legacy_fs_context, fc);
+ struct super_block *sb;
+ struct dentry *root;
+ int ret;
+
+ root = ctx->fc.fs_type->mount(ctx->fc.fs_type, ctx->fc.sb_flags,
+ ctx->fc.source, ctx->legacy_data);
+ if (IS_ERR(root))
+ return PTR_ERR(root);
+
+ sb = root->d_sb;
+ BUG_ON(!sb);
+
+ if ((ctx->fc.fs_type->fs_flags & FS_HAS_SUBTYPE) &&
+ !fc->subtype) {
+ ret = legacy_set_subtype(fc);
+ if (ret < 0)
+ goto err_sb;
+ }
+
+ ctx->fc.root = root;
+ return 0;
+
+err_sb:
+ dput(root);
+ deactivate_locked_super(sb);
+ return ret;
+}
+
+static const struct fs_context_operations legacy_fs_context_ops = {
+ .free = legacy_fs_context_free,
+ .dup = legacy_fs_context_dup,
+ .parse_option = legacy_parse_option,
+ .parse_monolithic = legacy_parse_monolithic,
+ .validate = legacy_validate,
+ .get_tree = legacy_get_tree,
+};
diff --git a/fs/internal.h b/fs/internal.h
index 48cee21b4f14..e7fb460e7ca4 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -89,7 +89,7 @@ extern struct file *get_empty_filp(void);
/*
* super.c
*/
-extern int do_remount_sb(struct super_block *, int, void *, int);
+extern int do_remount_sb(struct super_block *, int, void *, int, struct fs_context *);
extern bool trylock_super(struct super_block *sb);
extern struct dentry *mount_fs(struct file_system_type *,
int, const char *, void *);
diff --git a/fs/libfs.c b/fs/libfs.c
index 7ff3cb904acd..756e552709fa 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -9,6 +9,7 @@
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/mount.h>
+#include <linux/fs_context.h>
#include <linux/vfs.h>
#include <linux/quotaops.h>
#include <linux/mutex.h>
@@ -574,13 +575,27 @@ static DEFINE_SPINLOCK(pin_fs_lock);

int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
{
+ struct fs_context *fc;
struct vfsmount *mnt = NULL;
+ int ret;
+
spin_lock(&pin_fs_lock);
if (unlikely(!*mount)) {
spin_unlock(&pin_fs_lock);
- mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
+
+ fc = vfs_new_fs_context(type, NULL, 0, FS_CONTEXT_FOR_KERNEL_MOUNT);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
+
+ ret = vfs_get_tree(fc);
+ if (ret < 0)
+ return ret;
+
+ mnt = vfs_create_mount(fc);
+ put_fs_context(fc);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
+
spin_lock(&pin_fs_lock);
if (!*mount)
*mount = mnt;
diff --git a/fs/namespace.c b/fs/namespace.c
index a6508e4c0a90..d6b0b0067f6d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -25,8 +25,10 @@
#include <linux/magic.h>
#include <linux/bootmem.h>
#include <linux/task_work.h>
+#include <linux/file.h>
#include <linux/sched/task.h>
#include <uapi/linux/mount.h>
+#include <linux/fs_context.h>

#include "pnode.h"
#include "internal.h"
@@ -1017,55 +1019,6 @@ static struct mount *skip_mnt_tree(struct mount *p)
return p;
}

-struct vfsmount *
-vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
-{
- struct mount *mnt;
- struct dentry *root;
-
- if (!type)
- return ERR_PTR(-ENODEV);
-
- mnt = alloc_vfsmnt(name);
- if (!mnt)
- return ERR_PTR(-ENOMEM);
-
- if (flags & SB_KERNMOUNT)
- mnt->mnt.mnt_flags = MNT_INTERNAL;
-
- root = mount_fs(type, flags, name, data);
- if (IS_ERR(root)) {
- mnt_free_id(mnt);
- free_vfsmnt(mnt);
- return ERR_CAST(root);
- }
-
- mnt->mnt.mnt_root = root;
- mnt->mnt.mnt_sb = root->d_sb;
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt_parent = mnt;
- lock_mount_hash();
- list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
- unlock_mount_hash();
- return &mnt->mnt;
-}
-EXPORT_SYMBOL_GPL(vfs_kern_mount);
-
-struct vfsmount *
-vfs_submount(const struct dentry *mountpoint, struct file_system_type *type,
- const char *name, void *data)
-{
- /* Until it is worked out how to pass the user namespace
- * through from the parent mount to the submount don't support
- * unprivileged mounts with submounts.
- */
- if (mountpoint->d_sb->s_user_ns != &init_user_ns)
- return ERR_PTR(-EPERM);
-
- return vfs_kern_mount(type, SB_SUBMOUNT, name, data);
-}
-EXPORT_SYMBOL_GPL(vfs_submount);
-
static struct mount *clone_mnt(struct mount *old, struct dentry *root,
int flag)
{
@@ -1592,7 +1545,7 @@ static int do_umount(struct mount *mnt, int flags)
return -EPERM;
down_write(&sb->s_umount);
if (!sb_rdonly(sb))
- retval = do_remount_sb(sb, SB_RDONLY, NULL, 0);
+ retval = do_remount_sb(sb, SB_RDONLY, NULL, 0, NULL);
up_write(&sb->s_umount);
return retval;
}
@@ -2275,6 +2228,20 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
}

/*
+ * Parse the monolithic page of mount data given to sys_mount().
+ */
+static 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);
+}
+
+/*
* change filesystem flags. dir should be a physical root of filesystem.
* If you've mounted a non-root directory somewhere and want to do remount
* on it - tough luck.
@@ -2282,9 +2249,11 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
static int do_remount(struct path *path, int ms_flags, int sb_flags,
int mnt_flags, void *data)
{
+ struct fs_context *fc = NULL;
int err;
struct super_block *sb = path->mnt->mnt_sb;
struct mount *mnt = real_mount(path->mnt);
+ struct file_system_type *type = sb->s_type;

if (!check_mnt(mnt))
return -EINVAL;
@@ -2319,9 +2288,25 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
return -EPERM;
}

- err = security_sb_remount(sb, data);
- if (err)
- return err;
+ if (type->init_fs_context) {
+ fc = vfs_sb_reconfig(path->mnt, sb_flags);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
+
+ err = parse_monolithic_mount_data(fc, data);
+ if (err < 0)
+ goto err_fc;
+
+ if (fc->ops->validate) {
+ err = fc->ops->validate(fc);
+ if (err < 0)
+ goto err_fc;
+ }
+ } else {
+ err = security_sb_remount(sb, data);
+ if (err)
+ return err;
+ }

down_write(&sb->s_umount);
if (ms_flags & MS_BIND)
@@ -2329,7 +2314,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
else if (!capable(CAP_SYS_ADMIN))
err = -EPERM;
else
- err = do_remount_sb(sb, sb_flags, data, 0);
+ err = do_remount_sb(sb, sb_flags, data, 0, fc);
if (!err) {
lock_mount_hash();
mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
@@ -2338,6 +2323,9 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
unlock_mount_hash();
}
up_write(&sb->s_umount);
+err_fc:
+ if (fc)
+ put_fs_context(fc);
return err;
}

@@ -2421,29 +2409,6 @@ static int do_move_mount(struct path *path, const char *old_name)
return err;
}

-static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
-{
- int err;
- const char *subtype = strchr(fstype, '.');
- if (subtype) {
- subtype++;
- err = -EINVAL;
- if (!subtype[0])
- goto err;
- } else
- subtype = "";
-
- mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
- err = -ENOMEM;
- if (!mnt->mnt_sb->s_subtype)
- goto err;
- return mnt;
-
- err:
- mntput(mnt);
- return ERR_PTR(err);
-}
-
/*
* add a mount into a namespace's mount tree
*/
@@ -2491,40 +2456,89 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags);

/*
- * create a new mount for userspace and request it to be added into the
- * namespace's tree
+ * Create a new mount using a superblock configuration and request it
+ * be added to the namespace tree.
*/
-static int do_new_mount(struct path *path, const char *fstype, int sb_flags,
- int mnt_flags, const char *name, void *data)
+static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,
+ unsigned int mnt_flags)
{
- struct file_system_type *type;
struct vfsmount *mnt;
- int err;
-
- if (!fstype)
- return -EINVAL;
-
- type = get_fs_type(fstype);
- if (!type)
- return -ENODEV;
+ int ret;

- mnt = vfs_kern_mount(type, sb_flags, name, data);
- if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
- !mnt->mnt_sb->s_subtype)
- mnt = fs_set_subtype(mnt, fstype);
+ ret = security_sb_mountpoint(fc, mountpoint);
+ if (ret < 0)
+ return ret;;

- put_filesystem(type);
+ mnt = vfs_create_mount(fc);
if (IS_ERR(mnt))
return PTR_ERR(mnt);

+ ret = -EPERM;
if (mount_too_revealing(mnt, &mnt_flags)) {
- mntput(mnt);
- return -EPERM;
+ pr_warn("VFS: Mount too revealing\n");
+ goto err_mnt;
+ }
+
+ ret = do_add_mount(real_mount(mnt), mountpoint, mnt_flags);
+ if (ret < 0)
+ goto err_mnt;
+ return ret;
+
+err_mnt:
+ mntput(mnt);
+ return ret;
+}
+
+/*
+ * create a new mount for userspace and request it to be added into the
+ * namespace's tree
+ */
+static int do_new_mount(struct path *mountpoint, const char *fstype,
+ int sb_flags, int mnt_flags, const char *name,
+ void *data)
+{
+ struct file_system_type *fs_type;
+ struct fs_context *fc;
+ int err = -EINVAL;
+
+ if (!fstype)
+ goto err;
+
+ err = -ENODEV;
+ fs_type = get_fs_type(fstype);
+ if (!fs_type)
+ goto err;
+
+ fc = vfs_new_fs_context(fs_type, NULL, sb_flags,
+ FS_CONTEXT_FOR_USER_MOUNT);
+ put_filesystem(fs_type);
+ if (IS_ERR(fc)) {
+ err = PTR_ERR(fc);
+ goto err;
}

- err = do_add_mount(real_mount(mnt), path, mnt_flags);
+ err = vfs_set_fs_source(fc, name, name ? strlen(name) : 0);
+ if (err < 0)
+ goto err_fc;
+
+ err = parse_monolithic_mount_data(fc, data);
+ if (err < 0)
+ goto err_fc;
+
+ err = vfs_get_tree(fc);
+ if (err < 0)
+ goto err_fc;
+
+ err = do_new_mount_fc(fc, mountpoint, mnt_flags);
if (err)
- mntput(mnt);
+ goto err_fc;
+
+ put_fs_context(fc);
+ return 0;
+
+err_fc:
+ put_fs_context(fc);
+err:
return err;
}

@@ -3063,6 +3077,116 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
return ret;
}

+/**
+ * vfs_create_mount - Create a mount for a configured superblock
+ * fc: The configuration context with the superblock attached
+ *
+ * Create a mount to an already configured superblock. If necessary, the
+ * caller should invoke vfs_get_tree() before calling this.
+ *
+ * Note that this does not attach the mount to anything.
+ */
+struct vfsmount *vfs_create_mount(struct fs_context *fc)
+{
+ struct mount *mnt;
+
+ if (!fc->root)
+ return ERR_PTR(-EINVAL);
+
+ mnt = alloc_vfsmnt(fc->source ?: "none");
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
+
+ if (fc->purpose == FS_CONTEXT_FOR_KERNEL_MOUNT)
+ /* It's a longterm mount, don't release mnt until we unmount
+ * before file sys is unregistered
+ */
+ mnt->mnt.mnt_flags = MNT_INTERNAL;
+
+ atomic_inc(&fc->root->d_sb->s_active);
+ mnt->mnt.mnt_sb = fc->root->d_sb;
+ mnt->mnt.mnt_root = dget(fc->root);
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
+
+ lock_mount_hash();
+ list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);
+ unlock_mount_hash();
+ return &mnt->mnt;
+}
+EXPORT_SYMBOL(vfs_create_mount);
+
+struct vfsmount *vfs_kern_mount(struct file_system_type *type,
+ int sb_flags, const char *devname, void *data)
+{
+ struct fs_context *fc;
+ struct vfsmount *mnt;
+ int ret;
+
+ if (!type)
+ return ERR_PTR(-EINVAL);
+
+ fc = vfs_new_fs_context(type, NULL, sb_flags,
+ sb_flags & SB_KERNMOUNT ?
+ FS_CONTEXT_FOR_KERNEL_MOUNT :
+ FS_CONTEXT_FOR_USER_MOUNT);
+ if (IS_ERR(fc))
+ return ERR_CAST(fc);
+
+ ret = vfs_set_fs_source(fc, devname, devname ? strlen(devname) : 0);
+ if (ret < 0)
+ goto err_fc;
+
+ ret = parse_monolithic_mount_data(fc, data);
+ if (ret < 0)
+ goto err_fc;
+
+ ret = vfs_get_tree(fc);
+ if (ret < 0)
+ goto err_fc;
+
+ mnt = vfs_create_mount(fc);
+ if (IS_ERR(mnt)) {
+ ret = PTR_ERR(mnt);
+ goto err_fc;
+ }
+
+ put_fs_context(fc);
+ return mnt;
+
+err_fc:
+ put_fs_context(fc);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(vfs_kern_mount);
+
+struct vfsmount *
+vfs_submount(const struct dentry *mountpoint, struct file_system_type *type,
+ const char *name, void *data)
+{
+ /* Until it is worked out how to pass the user namespace
+ * through from the parent mount to the submount don't support
+ * unprivileged mounts with submounts.
+ */
+ if (mountpoint->d_sb->s_user_ns != &init_user_ns)
+ return ERR_PTR(-EPERM);
+
+ return vfs_kern_mount(type, MS_SUBMOUNT, name, data);
+}
+EXPORT_SYMBOL_GPL(vfs_submount);
+
+struct vfsmount *kern_mount(struct file_system_type *type)
+{
+ return vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
+}
+EXPORT_SYMBOL_GPL(kern_mount);
+
+struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
+{
+ return vfs_kern_mount(type, SB_KERNMOUNT, type->name, data);
+}
+EXPORT_SYMBOL_GPL(kern_mount_data);
+
/*
* Return true if path is reachable from root
*
@@ -3283,21 +3407,6 @@ void put_mnt_ns(struct mnt_namespace *ns)
free_mnt_ns(ns);
}

-struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
-{
- struct vfsmount *mnt;
- mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, data);
- if (!IS_ERR(mnt)) {
- /*
- * it is a longterm mount, don't release mnt until
- * we unmount before file sys is unregistered
- */
- real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
- }
- return mnt;
-}
-EXPORT_SYMBOL_GPL(kern_mount_data);
-
void kern_unmount(struct vfsmount *mnt)
{
/* release long term mount so mount point can be released */
diff --git a/fs/super.c b/fs/super.c
index 02da00410de8..e7d411d1d435 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -35,6 +35,7 @@
#include <linux/lockdep.h>
#include <linux/user_namespace.h>
#include <uapi/linux/mount.h>
+#include <linux/fs_context.h>
#include "internal.h"


@@ -173,16 +174,13 @@ static void destroy_super(struct super_block *s)
}

/**
- * alloc_super - create new superblock
- * @type: filesystem type superblock should belong to
- * @flags: the mount flags
- * @user_ns: User namespace for the super_block
+ * alloc_super - Create new superblock
+ * @fc: The filesystem configuration context
*
* Allocates and initializes a new &struct super_block. alloc_super()
* returns a pointer new superblock or %NULL if allocation had failed.
*/
-static struct super_block *alloc_super(struct file_system_type *type, int flags,
- struct user_namespace *user_ns)
+static struct super_block *alloc_super(struct fs_context *fc)
{
struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
static const struct super_operations default_op;
@@ -192,7 +190,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
return NULL;

INIT_LIST_HEAD(&s->s_mounts);
- s->s_user_ns = get_user_ns(user_ns);
+ s->s_user_ns = get_user_ns(fc->user_ns);

if (security_sb_alloc(s))
goto fail;
@@ -200,12 +198,12 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
for (i = 0; i < SB_FREEZE_LEVELS; i++) {
if (__percpu_init_rwsem(&s->s_writers.rw_sem[i],
sb_writers_name[i],
- &type->s_writers_key[i]))
+ &fc->fs_type->s_writers_key[i]))
goto fail;
}
init_waitqueue_head(&s->s_writers.wait_unfrozen);
s->s_bdi = &noop_backing_dev_info;
- s->s_flags = flags;
+ s->s_flags = fc->sb_flags;
if (s->s_user_ns != &init_user_ns)
s->s_iflags |= SB_I_NODEV;
INIT_HLIST_NODE(&s->s_instances);
@@ -222,7 +220,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
goto fail;

init_rwsem(&s->s_umount);
- lockdep_set_class(&s->s_umount, &type->s_umount_key);
+ lockdep_set_class(&s->s_umount, &fc->fs_type->s_umount_key);
/*
* sget() can have s_umount recursion.
*
@@ -242,7 +240,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
s->s_count = 1;
atomic_set(&s->s_active, 1);
mutex_init(&s->s_vfs_rename_mutex);
- lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
+ lockdep_set_class(&s->s_vfs_rename_mutex, &fc->fs_type->s_vfs_rename_key);
init_rwsem(&s->s_dquot.dqio_sem);
s->s_maxbytes = MAX_NON_LFS;
s->s_op = &default_op;
@@ -455,6 +453,96 @@ void generic_shutdown_super(struct super_block *sb)
EXPORT_SYMBOL(generic_shutdown_super);

/**
+ * sget_fc - Find or create a superblock
+ * @fc: Filesystem context.
+ * @test: Comparison callback
+ * @set: Setup callback
+ *
+ * Find or create a superblock using the parameters stored in the filesystem
+ * context and the two callback functions.
+ *
+ * If an extant superblock is matched, then that will be returned with an
+ * elevated reference count that the caller must transfer or discard.
+ *
+ * If no match is made, a new superblock will be allocated and basic
+ * initialisation will be performed (s_type, s_fs_info and s_id will be set and
+ * the set() callback will be invoked), the superblock will be published and it
+ * will be returned in a partially constructed state with SB_BORN and SB_ACTIVE
+ * as yet unset.
+ */
+struct super_block *sget_fc(struct fs_context *fc,
+ int (*test)(struct super_block *, struct fs_context *),
+ int (*set)(struct super_block *, struct fs_context *))
+{
+ struct super_block *s = NULL;
+ struct super_block *old;
+ int err;
+
+ if (!(fc->sb_flags & SB_KERNMOUNT) &&
+ fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
+ /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+ * over the namespace.
+ */
+ if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT) &&
+ !capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ else if (!ns_capable(fc->user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ }
+
+retry:
+ spin_lock(&sb_lock);
+ if (test) {
+ hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) {
+ if (!test(old, fc))
+ continue;
+ if (fc->user_ns != old->s_user_ns) {
+ spin_unlock(&sb_lock);
+ if (s) {
+ up_write(&s->s_umount);
+ destroy_super(s);
+ }
+ return ERR_PTR(-EBUSY);
+ }
+ if (!grab_super(old))
+ goto retry;
+ if (s) {
+ up_write(&s->s_umount);
+ destroy_super(s);
+ s = NULL;
+ }
+ return old;
+ }
+ }
+ if (!s) {
+ spin_unlock(&sb_lock);
+ s = alloc_super(fc);
+ if (!s)
+ return ERR_PTR(-ENOMEM);
+ goto retry;
+ }
+
+ s->s_fs_info = fc->s_fs_info;
+ err = set(s, fc);
+ if (err) {
+ s->s_fs_info = NULL;
+ spin_unlock(&sb_lock);
+ up_write(&s->s_umount);
+ destroy_super(s);
+ return ERR_PTR(err);
+ }
+ s->s_type = fc->fs_type;
+ strlcpy(s->s_id, s->s_type->name, sizeof(s->s_id));
+ list_add_tail(&s->s_list, &super_blocks);
+ hlist_add_head(&s->s_instances, &s->s_type->fs_supers);
+ spin_unlock(&sb_lock);
+ get_filesystem(s->s_type);
+ register_shrinker(&s->s_shrink);
+ return s;
+}
+EXPORT_SYMBOL(sget_fc);
+
+/**
* sget_userns - find or create a superblock
* @type: filesystem type superblock should belong to
* @test: comparison callback
@@ -503,7 +591,14 @@ struct super_block *sget_userns(struct file_system_type *type,
}
if (!s) {
spin_unlock(&sb_lock);
- s = alloc_super(type, (flags & ~SB_SUBMOUNT), user_ns);
+ {
+ struct fs_context fc = {
+ .fs_type = type,
+ .sb_flags = flags & ~SB_SUBMOUNT,
+ .user_ns = user_ns,
+ };
+ s = alloc_super(&fc);
+ }
if (!s)
return ERR_PTR(-ENOMEM);
goto retry;
@@ -805,10 +900,13 @@ struct super_block *user_get_super(dev_t dev)
* @sb_flags: revised superblock flags
* @data: the rest of options
* @force: whether or not to force the change
+ * @fc: the superblock config for filesystems that support it
+ * (NULL if called from emergency or umount)
*
* Alters the mount options of a mounted file system.
*/
-int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
+int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force,
+ struct fs_context *fc)
{
int retval;
int remount_ro;
@@ -850,8 +948,14 @@ int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
}
}

- if (sb->s_op->remount_fs) {
- retval = sb->s_op->remount_fs(sb, &sb_flags, data);
+ if (sb->s_op->remount_fs_fc ||
+ sb->s_op->remount_fs) {
+ if (sb->s_op->remount_fs_fc) {
+ retval = sb->s_op->remount_fs_fc(sb, fc);
+ sb_flags = fc->sb_flags;
+ } else {
+ retval = sb->s_op->remount_fs(sb, &sb_flags, data);
+ }
if (retval) {
if (!force)
goto cancel_readonly;
@@ -898,7 +1002,7 @@ static void do_emergency_remount(struct work_struct *work)
/*
* What lock protects sb->s_flags??
*/
- do_remount_sb(sb, SB_RDONLY, NULL, 1);
+ do_remount_sb(sb, SB_RDONLY, NULL, 1, NULL);
}
up_write(&sb->s_umount);
spin_lock(&sb_lock);
@@ -1048,6 +1152,89 @@ struct dentry *mount_ns(struct file_system_type *fs_type,

EXPORT_SYMBOL(mount_ns);

+static int set_anon_super_fc(struct super_block *sb, struct fs_context *fc)
+{
+ return set_anon_super(sb, NULL);
+}
+
+static int test_keyed_super(struct super_block *sb, struct fs_context *fc)
+{
+ return sb->s_fs_info == fc->s_fs_info;
+}
+
+static int test_single_super(struct super_block *s, struct fs_context *fc)
+{
+ return 1;
+}
+
+/**
+ * vfs_get_super - Get a superblock with a search key set in s_fs_info.
+ * @fc: The filesystem context holding the parameters
+ * @keying: How to distinguish superblocks
+ * @fill_super: Helper to initialise a new superblock
+ *
+ * Search for a superblock and create a new one if not found. The search
+ * criterion is controlled by @keying. If the search fails, a new superblock
+ * is created and @fill_super() is called to initialise it.
+ *
+ * @keying can take one of a number of values:
+ *
+ * (1) vfs_get_single_super - Only one superblock of this type may exist on the
+ * system. This is typically used for special system filesystems.
+ *
+ * (2) vfs_get_keyed_super - Multiple superblocks may exist, but they must have
+ * distinct keys (where the key is in s_fs_info). Searching for the same
+ * key again will turn up the superblock for that key.
+ *
+ * (3) vfs_get_independent_super - Multiple superblocks may exist and are
+ * unkeyed. Each call will get a new superblock.
+ *
+ * A permissions check is made by sget_fc() unless we're getting a superblock
+ * for a kernel-internal mount or a submount.
+ */
+int vfs_get_super(struct fs_context *fc,
+ enum vfs_get_super_keying keying,
+ int (*fill_super)(struct super_block *sb,
+ struct fs_context *fc))
+{
+ int (*test)(struct super_block *, struct fs_context *);
+ struct super_block *sb;
+
+ switch (keying) {
+ case vfs_get_single_super:
+ test = test_single_super;
+ break;
+ case vfs_get_keyed_super:
+ test = test_keyed_super;
+ break;
+ case vfs_get_independent_super:
+ test = NULL;
+ break;
+ default:
+ BUG();
+ }
+
+ sb = sget_fc(fc, test, set_anon_super_fc);
+ if (IS_ERR(sb))
+ return PTR_ERR(sb);
+
+ if (!sb->s_root) {
+ int err;
+ err = fill_super(sb, fc);
+ if (err) {
+ deactivate_locked_super(sb);
+ return err;
+ }
+
+ sb->s_flags |= SB_ACTIVE;
+ }
+
+ if (!fc->root)
+ fc->root = dget(sb->s_root);
+ return 0;
+}
+EXPORT_SYMBOL(vfs_get_super);
+
#ifdef CONFIG_BLOCK
static int set_bdev_super(struct super_block *s, void *data)
{
@@ -1196,7 +1383,7 @@ struct dentry *mount_single(struct file_system_type *fs_type,
}
s->s_flags |= SB_ACTIVE;
} else {
- do_remount_sb(s, flags, data, 0);
+ do_remount_sb(s, flags, data, 0, NULL);
}
return dget(s->s_root);
}
@@ -1529,3 +1716,76 @@ int thaw_super(struct super_block *sb)
return 0;
}
EXPORT_SYMBOL(thaw_super);
+
+/**
+ * vfs_get_tree - Get the mountable root
+ * @fc: The superblock configuration context.
+ *
+ * The filesystem is invoked to get or create a superblock which can then later
+ * be used for mounting. The filesystem places a pointer to the root to be
+ * used for mounting in @fc->root.
+ */
+int vfs_get_tree(struct fs_context *fc)
+{
+ struct super_block *sb;
+ int ret;
+
+ if (fc->root)
+ return -EBUSY;
+
+ if (fc->ops->validate) {
+ ret = fc->ops->validate(fc);
+ if (ret < 0)
+ return ret;
+ }
+
+ /* The filesystem may transfer preallocated resources from the
+ * configuration context to the superblock, thereby rendering the
+ * config unusable for another attempt at creation if this one fails.
+ */
+ if (fc->degraded)
+ return -EBUSY;
+
+ /* Get the mountable root in fc->root, with a ref on the root and a ref
+ * on the superblock.
+ */
+ ret = fc->ops->get_tree(fc);
+ if (ret < 0)
+ return ret;
+
+ BUG_ON(!fc->root);
+ sb = fc->root->d_sb;
+ WARN_ON(!sb->s_bdi);
+
+ ret = security_sb_get_tree(fc);
+ if (ret < 0)
+ goto err_sb;
+
+ ret = -ENOMEM;
+ if (fc->subtype && !sb->s_subtype) {
+ sb->s_subtype = kstrdup(fc->subtype, GFP_KERNEL);
+ if (!sb->s_subtype)
+ goto err_sb;
+ }
+
+ sb->s_flags |= SB_BORN;
+
+ /* Filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
+ * but s_maxbytes was an unsigned long long for many releases. Throw
+ * this warning for a little while to try and catch filesystems that
+ * violate this rule.
+ */
+ WARN(sb->s_maxbytes < 0,
+ "%s set sb->s_maxbytes to negative value (%lld)\n",
+ fc->fs_type->name, sb->s_maxbytes);
+
+ up_write(&sb->s_umount);
+ return 0;
+
+err_sb:
+ dput(fc->root);
+ fc->root = NULL;
+ deactivate_locked_super(sb);
+ return ret;
+}
+EXPORT_SYMBOL(vfs_get_tree);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bd2ee00e03ff..f391263c62a1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -58,6 +58,7 @@ struct workqueue_struct;
struct iov_iter;
struct fscrypt_info;
struct fscrypt_operations;
+struct fs_context;

extern void __init inode_init(void);
extern void __init inode_init_early(void);
@@ -717,6 +718,11 @@ static inline void inode_unlock(struct inode *inode)
up_write(&inode->i_rwsem);
}

+static inline int inode_lock_killable(struct inode *inode)
+{
+ return down_write_killable(&inode->i_rwsem);
+}
+
static inline void inode_lock_shared(struct inode *inode)
{
down_read(&inode->i_rwsem);
@@ -1814,6 +1820,7 @@ struct super_operations {
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
+ int (*remount_fs_fc) (struct super_block *, struct fs_context *);
void (*umount_begin) (struct super_block *);

int (*show_options)(struct seq_file *, struct dentry *);
@@ -2072,8 +2079,10 @@ struct file_system_type {
#define FS_HAS_SUBTYPE 4
#define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */
#define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */
+ unsigned short fs_context_size; /* Size of superblock config context to allocate */
struct dentry *(*mount) (struct file_system_type *, int,
const char *, void *);
+ int (*init_fs_context)(struct fs_context *, struct super_block *);
void (*kill_sb) (struct super_block *);
struct module *owner;
struct file_system_type * next;
@@ -2113,6 +2122,9 @@ void deactivate_locked_super(struct super_block *sb);
int set_anon_super(struct super_block *s, void *data);
int get_anon_bdev(dev_t *);
void free_anon_bdev(dev_t);
+struct super_block *sget_fc(struct fs_context *fc,
+ int (*test)(struct super_block *, struct fs_context *),
+ int (*set)(struct super_block *, struct fs_context *));
struct super_block *sget_userns(struct file_system_type *type,
int (*test)(struct super_block *,void *),
int (*set)(struct super_block *,void *),
@@ -2155,8 +2167,8 @@ mount_pseudo(struct file_system_type *fs_type, char *name,

extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
-extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
-#define kern_mount(type) kern_mount_data(type, NULL)
+extern struct vfsmount *kern_mount(struct file_system_type *);
+extern struct vfsmount *kern_mount_data(struct file_system_type *, void *);
extern void kern_unmount(struct vfsmount *mnt);
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index 645c57e10764..8af6ff0e869e 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -27,9 +27,10 @@ struct user_namespace;
struct vfsmount;

enum fs_context_purpose {
- FS_CONTEXT_FOR_NEW, /* New superblock for direct mount */
+ FS_CONTEXT_FOR_USER_MOUNT, /* New superblock for user-specified mount */
+ FS_CONTEXT_FOR_KERNEL_MOUNT, /* New superblock for kernel-internal mount */
FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */
- FS_CONTEXT_FOR_REMOUNT, /* Superblock reconfiguration for remount */
+ FS_CONTEXT_FOR_REMOUNT, /* Superblock reconfiguration for remount */
};

/*
@@ -53,7 +54,8 @@ struct fs_context {
char *source; /* The source name (eg. device) */
char *subtype; /* The subtype to set on the superblock */
void *security; /* The LSM context */
- unsigned int sb_flags; /* The superblock flags (MS_*) */
+ void *s_fs_info; /* Proposed s_fs_info */
+ unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
bool sloppy; /* Unrecognised options are okay */
bool silent;
bool degraded; /* True if the context can't be reused */
@@ -70,4 +72,33 @@ struct fs_context_operations {
int (*get_tree)(struct fs_context *fc);
};

+/*
+ * fs_context manipulation functions.
+ */
+extern struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type,
+ struct super_block *src_sb,
+ unsigned int ms_flags,
+ enum fs_context_purpose purpose);
+extern struct fs_context *vfs_sb_reconfig(struct vfsmount *mnt,
+ unsigned int ms_flags);
+extern struct fs_context *vfs_dup_fs_context(struct fs_context *src);
+extern int vfs_set_fs_source(struct fs_context *fc, const char *source, size_t slen);
+extern int vfs_parse_mount_option(struct fs_context *fc, char *data);
+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);
+
+/*
+ * sget() wrapper to be called from the ->get_tree() op.
+ */
+enum vfs_get_super_keying {
+ vfs_get_single_super, /* Only one such superblock may exist */
+ vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */
+ vfs_get_independent_super, /* Multiple independent superblocks may exist */
+};
+extern int vfs_get_super(struct fs_context *fc,
+ enum vfs_get_super_keying keying,
+ int (*fill_super)(struct super_block *sb,
+ struct fs_context *fc));
+
#endif /* _LINUX_FS_CONTEXT_H */
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 85398ba0b533..74aeccb041a2 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -91,7 +91,7 @@
* @fs_context_free:
* Clean up a filesystem context.
* @fc indicates the filesystem context.
- * @fs_context_parse_one:
+ * @fs_context_parse_option:
* Userspace provided an option to configure a superblock. The LSM may
* reject it with an error and may use it for itself, in which case it
* should return 1; otherwise it should return 0 to pass it on to the
@@ -1419,7 +1419,7 @@ union security_list_options {
int (*fs_context_alloc)(struct fs_context *fc, struct super_block *src_sb);
int (*fs_context_dup)(struct fs_context *fc, struct fs_context *src_sc);
void (*fs_context_free)(struct fs_context *fc);
- int (*fs_context_parse_one)(struct fs_context *fc, char *opt);
+ int (*fs_context_parse_option)(struct fs_context *fc, char *opt);
int (*sb_get_tree)(struct fs_context *fc);
int (*sb_mountpoint)(struct fs_context *fc, struct path *mountpoint);

@@ -1745,7 +1745,7 @@ struct security_hook_heads {
struct list_head fs_context_alloc;
struct list_head fs_context_dup;
struct list_head fs_context_free;
- struct list_head fs_context_parse_one;
+ struct list_head fs_context_parse_option;
struct list_head sb_get_tree;
struct list_head sb_mountpoint;
struct list_head sb_alloc_security;
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 1ce85e6fd95f..f47306b4bf72 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -20,6 +20,7 @@ struct super_block;
struct vfsmount;
struct dentry;
struct mnt_namespace;
+struct fs_context;

#define MNT_NOSUID 0x01
#define MNT_NODEV 0x02
@@ -87,6 +88,7 @@ struct path;
extern struct vfsmount *clone_private_mount(const struct path *path);

struct file_system_type;
+extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
int flags, const char *name,
void *data);
diff --git a/security/security.c b/security/security.c
index 55383a0e764d..7826a493c02a 100644
--- a/security/security.c
+++ b/security/security.c
@@ -366,9 +366,9 @@ void security_fs_context_free(struct fs_context *fc)
call_void_hook(fs_context_free, fc);
}

-int security_fs_context_parse_one(struct fs_context *fc, char *opt)
+int security_fs_context_parse_option(struct fs_context *fc, char *p)
{
- return call_int_hook(fs_context_parse_one, 0, fc, opt);
+ return call_int_hook(fs_context_parse_option, 0, fc, p);
}

int security_sb_get_tree(struct fs_context *fc)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0dda7350b5af..ca57e61f9c43 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2927,7 +2927,7 @@ static void selinux_fs_context_free(struct fs_context *fc)
fc->security = NULL;
}

-static int selinux_fs_context_parse_one(struct fs_context *fc, char *opt)
+static int selinux_fs_context_parse_option(struct fs_context *fc, char *opt)
{
struct security_mnt_opts *opts = fc->security;
substring_t args[MAX_OPT_ARGS];
@@ -3014,7 +3014,7 @@ static int selinux_sb_get_tree(struct fs_context *fc)
return rc;

/* Allow all mounts performed by the kernel */
- if (fc->sb_flags & MS_KERNMOUNT)
+ if (fc->purpose & FS_CONTEXT_FOR_KERNEL_MOUNT)
return 0;

ad.type = LSM_AUDIT_DATA_DENTRY;
@@ -6445,7 +6445,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(fs_context_alloc, selinux_fs_context_alloc),
LSM_HOOK_INIT(fs_context_dup, selinux_fs_context_dup),
LSM_HOOK_INIT(fs_context_free, selinux_fs_context_free),
- LSM_HOOK_INIT(fs_context_parse_one, selinux_fs_context_parse_one),
+ LSM_HOOK_INIT(fs_context_parse_option, selinux_fs_context_parse_option),
LSM_HOOK_INIT(sb_get_tree, selinux_sb_get_tree),
LSM_HOOK_INIT(sb_mountpoint, selinux_sb_mountpoint),

\
 
 \ /
  Last update: 2017-10-06 17:56    [W:0.235 / U:0.720 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site