Revision 98bda63e20daab95bdc084ce00459a4f622a0505 authored by Roman Kiryanov on 19 February 2020, 21:40:06 UTC, committed by David S. Miller on 20 February 2020, 23:02:02 UTC
The description says 'If unsure, say N.' but the module is built as M by default (once the dependencies are satisfied). When the module is selected (Y or M), it enables NETFILTER_FAMILY_BRIDGE and SKB_EXTENSIONS which alter kernel internal structures. We (Android Studio Emulator) currently do not use this module and think this it is more consistent to have it disabled by default as opposite to disabling it explicitly to prevent enabling NETFILTER_FAMILY_BRIDGE and SKB_EXTENSIONS. Signed-off-by: Roman Kiryanov <rkir@google.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent ac2fcfa
mntpt.c
// SPDX-License-Identifier: GPL-2.0-or-later
/* mountpoint management
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/gfp.h>
#include <linux/fs_context.h>
#include "internal.h"
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
static int afs_mntpt_open(struct inode *inode, struct file *file);
static void afs_mntpt_expiry_timed_out(struct work_struct *work);
const struct file_operations afs_mntpt_file_operations = {
.open = afs_mntpt_open,
.llseek = noop_llseek,
};
const struct inode_operations afs_mntpt_inode_operations = {
.lookup = afs_mntpt_lookup,
.readlink = page_readlink,
.getattr = afs_getattr,
.listxattr = afs_listxattr,
};
const struct inode_operations afs_autocell_inode_operations = {
.getattr = afs_getattr,
};
static LIST_HEAD(afs_vfsmounts);
static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
static const char afs_root_volume[] = "root.cell";
/*
* no valid lookup procedure on this sort of dir
*/
static struct dentry *afs_mntpt_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
_enter("%p,%p{%pd2}", dir, dentry, dentry);
return ERR_PTR(-EREMOTE);
}
/*
* no valid open procedure on this sort of dir
*/
static int afs_mntpt_open(struct inode *inode, struct file *file)
{
_enter("%p,%p{%pD2}", inode, file, file);
return -EREMOTE;
}
/*
* Set the parameters for the proposed superblock.
*/
static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
{
struct afs_fs_context *ctx = fc->fs_private;
struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
struct afs_cell *cell;
const char *p;
int ret;
if (fc->net_ns != src_as->net_ns) {
put_net(fc->net_ns);
fc->net_ns = get_net(src_as->net_ns);
}
if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (ctx->cell) {
afs_put_cell(ctx->net, ctx->cell);
ctx->cell = NULL;
}
if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
/* if the directory is a pseudo directory, use the d_name */
unsigned size = mntpt->d_name.len;
if (size < 2)
return -ENOENT;
p = mntpt->d_name.name;
if (mntpt->d_name.name[0] == '.') {
size--;
p++;
ctx->type = AFSVL_RWVOL;
ctx->force = true;
}
if (size > AFS_MAXCELLNAME)
return -ENAMETOOLONG;
cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
if (IS_ERR(cell)) {
pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
return PTR_ERR(cell);
}
ctx->cell = cell;
ctx->volname = afs_root_volume;
ctx->volnamesz = sizeof(afs_root_volume) - 1;
} else {
/* read the contents of the AFS special symlink */
struct page *page;
loff_t size = i_size_read(d_inode(mntpt));
char *buf;
if (src_as->cell)
ctx->cell = afs_get_cell(src_as->cell);
if (size < 2 || size > PAGE_SIZE - 1)
return -EINVAL;
page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
if (IS_ERR(page))
return PTR_ERR(page);
if (PageError(page)) {
ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
put_page(page);
return ret;
}
buf = kmap(page);
ret = -EINVAL;
if (buf[size - 1] == '.')
ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
kunmap(page);
put_page(page);
if (ret < 0)
return ret;
}
return 0;
}
/*
* create a vfsmount to be automounted
*/
static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
{
struct fs_context *fc;
struct vfsmount *mnt;
int ret;
BUG_ON(!d_inode(mntpt));
fc = fs_context_for_submount(&afs_fs_type, mntpt);
if (IS_ERR(fc))
return ERR_CAST(fc);
ret = afs_mntpt_set_params(fc, mntpt);
if (!ret)
mnt = fc_mount(fc);
else
mnt = ERR_PTR(ret);
put_fs_context(fc);
return mnt;
}
/*
* handle an automount point
*/
struct vfsmount *afs_d_automount(struct path *path)
{
struct vfsmount *newmnt;
_enter("{%pd}", path->dentry);
newmnt = afs_mntpt_do_automount(path->dentry);
if (IS_ERR(newmnt))
return newmnt;
mntget(newmnt); /* prevent immediate expiration */
mnt_set_expiry(newmnt, &afs_vfsmounts);
queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
_leave(" = %p", newmnt);
return newmnt;
}
/*
* handle mountpoint expiry timer going off
*/
static void afs_mntpt_expiry_timed_out(struct work_struct *work)
{
_enter("");
if (!list_empty(&afs_vfsmounts)) {
mark_mounts_for_expiry(&afs_vfsmounts);
queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
afs_mntpt_expiry_timeout * HZ);
}
_leave("");
}
/*
* kill the AFS mountpoint timer if it's still running
*/
void afs_mntpt_kill_timer(void)
{
_enter("");
ASSERT(list_empty(&afs_vfsmounts));
cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
}
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