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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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944c74f472
In AFS, mountpoints appear as symlinks with mode 0644 and normal symlinks have mode 0777, so use this to distinguish them rather than reading the content and parsing it. In the case of a mountpoint, the symlink body is a formatted string indicating the location of the target volume. Note that with this, kAFS no longer 'pre-fetches' the contents of symlinks, so afs_readpage() may fail with an access-denial because when the VFS calls d_automount(), it wraps the call in an credentials override that sets the initial creds - thereby preventing access to the caller's keyrings and the authentication keys held therein. To this end, a patch reverting that change to the VFS is required also. Reported-by: Jeffrey Altman <jaltman@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com>
218 lines
5.2 KiB
C
218 lines
5.2 KiB
C
/* mountpoint management
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*
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* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/gfp.h>
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#include "internal.h"
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags);
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static int afs_mntpt_open(struct inode *inode, struct file *file);
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static void afs_mntpt_expiry_timed_out(struct work_struct *work);
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const struct file_operations afs_mntpt_file_operations = {
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.open = afs_mntpt_open,
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.llseek = noop_llseek,
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};
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const struct inode_operations afs_mntpt_inode_operations = {
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.lookup = afs_mntpt_lookup,
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.readlink = page_readlink,
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.getattr = afs_getattr,
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};
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const struct inode_operations afs_autocell_inode_operations = {
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.getattr = afs_getattr,
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};
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static LIST_HEAD(afs_vfsmounts);
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static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
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static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
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/*
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* no valid lookup procedure on this sort of dir
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*/
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static struct dentry *afs_mntpt_lookup(struct inode *dir,
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struct dentry *dentry,
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unsigned int flags)
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{
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_enter("%p,%p{%pd2}", dir, dentry, dentry);
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return ERR_PTR(-EREMOTE);
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}
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/*
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* no valid open procedure on this sort of dir
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*/
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static int afs_mntpt_open(struct inode *inode, struct file *file)
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{
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_enter("%p,%p{%pD2}", inode, file, file);
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return -EREMOTE;
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}
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/*
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* create a vfsmount to be automounted
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*/
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static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
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{
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struct afs_super_info *super;
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struct vfsmount *mnt;
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struct afs_vnode *vnode;
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struct page *page;
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char *devname, *options;
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bool rwpath = false;
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int ret;
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_enter("{%pd}", mntpt);
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BUG_ON(!d_inode(mntpt));
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ret = -ENOMEM;
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devname = (char *) get_zeroed_page(GFP_KERNEL);
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if (!devname)
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goto error_no_devname;
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options = (char *) get_zeroed_page(GFP_KERNEL);
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if (!options)
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goto error_no_options;
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vnode = AFS_FS_I(d_inode(mntpt));
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if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
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/* if the directory is a pseudo directory, use the d_name */
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static const char afs_root_cell[] = ":root.cell.";
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unsigned size = mntpt->d_name.len;
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ret = -ENOENT;
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if (size < 2 || size > AFS_MAXCELLNAME)
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goto error_no_page;
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if (mntpt->d_name.name[0] == '.') {
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devname[0] = '#';
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memcpy(devname + 1, mntpt->d_name.name, size - 1);
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memcpy(devname + size, afs_root_cell,
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sizeof(afs_root_cell));
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rwpath = true;
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} else {
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devname[0] = '%';
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memcpy(devname + 1, mntpt->d_name.name, size);
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memcpy(devname + size + 1, afs_root_cell,
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sizeof(afs_root_cell));
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}
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} else {
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/* read the contents of the AFS special symlink */
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loff_t size = i_size_read(d_inode(mntpt));
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char *buf;
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ret = -EINVAL;
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if (size > PAGE_SIZE - 1)
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goto error_no_page;
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page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
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if (IS_ERR(page)) {
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ret = PTR_ERR(page);
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goto error_no_page;
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}
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ret = -EIO;
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if (PageError(page))
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goto error;
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buf = kmap_atomic(page);
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memcpy(devname, buf, size);
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kunmap_atomic(buf);
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put_page(page);
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page = NULL;
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}
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/* work out what options we want */
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super = AFS_FS_S(mntpt->d_sb);
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memcpy(options, "cell=", 5);
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strcpy(options + 5, super->volume->cell->name);
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if (super->volume->type == AFSVL_RWVOL || rwpath)
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strcat(options, ",rwpath");
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/* try and do the mount */
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_debug("--- attempting mount %s -o %s ---", devname, options);
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mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);
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_debug("--- mount result %p ---", mnt);
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free_page((unsigned long) devname);
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free_page((unsigned long) options);
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_leave(" = %p", mnt);
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return mnt;
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error:
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put_page(page);
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error_no_page:
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free_page((unsigned long) options);
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error_no_options:
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free_page((unsigned long) devname);
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error_no_devname:
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_leave(" = %d", ret);
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return ERR_PTR(ret);
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}
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/*
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* handle an automount point
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*/
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struct vfsmount *afs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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_enter("{%pd}", path->dentry);
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newmnt = afs_mntpt_do_automount(path->dentry);
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if (IS_ERR(newmnt))
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return newmnt;
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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_leave(" = %p", newmnt);
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return newmnt;
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}
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/*
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* handle mountpoint expiry timer going off
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*/
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static void afs_mntpt_expiry_timed_out(struct work_struct *work)
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{
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_enter("");
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if (!list_empty(&afs_vfsmounts)) {
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mark_mounts_for_expiry(&afs_vfsmounts);
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queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
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afs_mntpt_expiry_timeout * HZ);
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}
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_leave("");
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}
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/*
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* kill the AFS mountpoint timer if it's still running
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*/
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void afs_mntpt_kill_timer(void)
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{
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_enter("");
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ASSERT(list_empty(&afs_vfsmounts));
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cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
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}
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