linux/fs/afs/dir_silly.c
David Howells 874c8ca1e6 netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context
While randstruct was satisfied with using an open-coded "void *" offset
cast for the netfs_i_context <-> inode casting, __builtin_object_size() as
used by FORTIFY_SOURCE was not as easily fooled.  This was causing the
following complaint[1] from gcc v12:

  In file included from include/linux/string.h:253,
                   from include/linux/ceph/ceph_debug.h:7,
                   from fs/ceph/inode.c:2:
  In function 'fortify_memset_chk',
      inlined from 'netfs_i_context_init' at include/linux/netfs.h:326:2,
      inlined from 'ceph_alloc_inode' at fs/ceph/inode.c:463:2:
  include/linux/fortify-string.h:242:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
    242 |                         __write_overflow_field(p_size_field, size);
        |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by embedding a struct inode into struct netfs_i_context (which
should perhaps be renamed to struct netfs_inode).  The struct inode
vfs_inode fields are then removed from the 9p, afs, ceph and cifs inode
structs and vfs_inode is then simply changed to "netfs.inode" in those
filesystems.

Further, rename netfs_i_context to netfs_inode, get rid of the
netfs_inode() function that converted a netfs_i_context pointer to an
inode pointer (that can now be done with &ctx->inode) and rename the
netfs_i_context() function to netfs_inode() (which is now a wrapper
around container_of()).

Most of the changes were done with:

  perl -p -i -e 's/vfs_inode/netfs.inode/'g \
        `git grep -l 'vfs_inode' -- fs/{9p,afs,ceph,cifs}/*.[ch]`

Kees suggested doing it with a pair structure[2] and a special
declarator to insert that into the network filesystem's inode
wrapper[3], but I think it's cleaner to embed it - and then it doesn't
matter if struct randomisation reorders things.

Dave Chinner suggested using a filesystem-specific VFS_I() function in
each filesystem to convert that filesystem's own inode wrapper struct
into the VFS inode struct[4].

Version #2:
 - Fix a couple of missed name changes due to a disabled cifs option.
 - Rename nfs_i_context to nfs_inode
 - Use "netfs" instead of "nic" as the member name in per-fs inode wrapper
   structs.

[ This also undoes commit 507160f46c ("netfs: gcc-12: temporarily
  disable '-Wattribute-warning' for now") that is no longer needed ]

Fixes: bc899ee1c8 ("netfs: Add a netfs inode context")
Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
cc: Jonathan Corbet <corbet@lwn.net>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Steve French <smfrench@gmail.com>
cc: William Kucharski <william.kucharski@oracle.com>
cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
cc: Dave Chinner <david@fromorbit.com>
cc: linux-doc@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: samba-technical@lists.samba.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-hardening@vger.kernel.org
Link: https://lore.kernel.org/r/d2ad3a3d7bdd794c6efb562d2f2b655fb67756b9.camel@kernel.org/ [1]
Link: https://lore.kernel.org/r/20220517210230.864239-1-keescook@chromium.org/ [2]
Link: https://lore.kernel.org/r/20220518202212.2322058-1-keescook@chromium.org/ [3]
Link: https://lore.kernel.org/r/20220524101205.GI2306852@dread.disaster.area/ [4]
Link: https://lore.kernel.org/r/165296786831.3591209.12111293034669289733.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165305805651.4094995.7763502506786714216.stgit@warthog.procyon.org.uk # v2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-09 13:55:00 -07:00

283 lines
7.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS silly rename handling
*
* Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from NFS's sillyrename.
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>
#include "internal.h"
static void afs_silly_rename_success(struct afs_operation *op)
{
_enter("op=%08x", op->debug_id);
afs_check_dir_conflict(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[0]);
}
static void afs_silly_rename_edit_dir(struct afs_operation *op)
{
struct afs_vnode_param *dvp = &op->file[0];
struct afs_vnode *dvnode = dvp->vnode;
struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
struct dentry *old = op->dentry;
struct dentry *new = op->dentry_2;
spin_lock(&old->d_lock);
old->d_flags |= DCACHE_NFSFS_RENAMED;
spin_unlock(&old->d_lock);
if (dvnode->silly_key != op->key) {
key_put(dvnode->silly_key);
dvnode->silly_key = key_get(op->key);
}
down_write(&dvnode->validate_lock);
if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) {
afs_edit_dir_remove(dvnode, &old->d_name,
afs_edit_dir_for_silly_0);
afs_edit_dir_add(dvnode, &new->d_name,
&vnode->fid, afs_edit_dir_for_silly_1);
}
up_write(&dvnode->validate_lock);
}
static const struct afs_operation_ops afs_silly_rename_operation = {
.issue_afs_rpc = afs_fs_rename,
.issue_yfs_rpc = yfs_fs_rename,
.success = afs_silly_rename_success,
.edit_dir = afs_silly_rename_edit_dir,
};
/*
* Actually perform the silly rename step.
*/
static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *old, struct dentry *new,
struct key *key)
{
struct afs_operation *op;
_enter("%pd,%pd", old, new);
op = afs_alloc_operation(key, dvnode->volume);
if (IS_ERR(op))
return PTR_ERR(op);
afs_op_set_vnode(op, 0, dvnode);
afs_op_set_vnode(op, 1, dvnode);
op->file[0].dv_delta = 1;
op->file[1].dv_delta = 1;
op->file[0].modification = true;
op->file[1].modification = true;
op->file[0].update_ctime = true;
op->file[1].update_ctime = true;
op->dentry = old;
op->dentry_2 = new;
op->ops = &afs_silly_rename_operation;
trace_afs_silly_rename(vnode, false);
return afs_do_sync_operation(op);
}
/*
* Perform silly-rename of a dentry.
*
* AFS is stateless and the server doesn't know when the client is holding a
* file open. To prevent application problems when a file is unlinked while
* it's still open, the client performs a "silly-rename". That is, it renames
* the file to a hidden file in the same directory, and only performs the
* unlink once the last reference to it is put.
*
* The final cleanup is done during dentry_iput.
*/
int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *dentry, struct key *key)
{
static unsigned int sillycounter;
struct dentry *sdentry = NULL;
unsigned char silly[16];
int ret = -EBUSY;
_enter("");
/* We don't allow a dentry to be silly-renamed twice. */
if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
return -EBUSY;
sdentry = NULL;
do {
int slen;
dput(sdentry);
sillycounter++;
/* Create a silly name. Note that the ".__afs" prefix is
* understood by the salvager and must not be changed.
*/
slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
sdentry = lookup_one_len(silly, dentry->d_parent, slen);
/* N.B. Better to return EBUSY here ... it could be dangerous
* to delete the file while it's in use.
*/
if (IS_ERR(sdentry))
goto out;
} while (!d_is_negative(sdentry));
ihold(&vnode->netfs.inode);
ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
switch (ret) {
case 0:
/* The rename succeeded. */
set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
d_move(dentry, sdentry);
break;
case -ERESTARTSYS:
/* The result of the rename is unknown. Play it safe by forcing
* a new lookup.
*/
d_drop(dentry);
d_drop(sdentry);
}
iput(&vnode->netfs.inode);
dput(sdentry);
out:
_leave(" = %d", ret);
return ret;
}
static void afs_silly_unlink_success(struct afs_operation *op)
{
_enter("op=%08x", op->debug_id);
afs_check_dir_conflict(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[0]);
afs_vnode_commit_status(op, &op->file[1]);
afs_update_dentry_version(op, &op->file[0], op->dentry);
}
static void afs_silly_unlink_edit_dir(struct afs_operation *op)
{
struct afs_vnode_param *dvp = &op->file[0];
struct afs_vnode *dvnode = dvp->vnode;
_enter("op=%08x", op->debug_id);
down_write(&dvnode->validate_lock);
if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
afs_edit_dir_remove(dvnode, &op->dentry->d_name,
afs_edit_dir_for_unlink);
up_write(&dvnode->validate_lock);
}
static const struct afs_operation_ops afs_silly_unlink_operation = {
.issue_afs_rpc = afs_fs_remove_file,
.issue_yfs_rpc = yfs_fs_remove_file,
.success = afs_silly_unlink_success,
.aborted = afs_check_for_remote_deletion,
.edit_dir = afs_silly_unlink_edit_dir,
};
/*
* Tell the server to remove a sillyrename file.
*/
static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
struct dentry *dentry, struct key *key)
{
struct afs_operation *op;
_enter("");
op = afs_alloc_operation(NULL, dvnode->volume);
if (IS_ERR(op))
return PTR_ERR(op);
afs_op_set_vnode(op, 0, dvnode);
afs_op_set_vnode(op, 1, vnode);
op->file[0].dv_delta = 1;
op->file[0].modification = true;
op->file[0].update_ctime = true;
op->file[1].op_unlinked = true;
op->file[1].update_ctime = true;
op->dentry = dentry;
op->ops = &afs_silly_unlink_operation;
trace_afs_silly_rename(vnode, true);
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
/* If there was a conflict with a third party, check the status of the
* unlinked vnode.
*/
if (op->error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
op->file[1].update_ctime = false;
op->fetch_status.which = 1;
op->ops = &afs_fetch_status_operation;
afs_begin_vnode_operation(op);
afs_wait_for_operation(op);
}
return afs_put_operation(op);
}
/*
* Remove sillyrename file on iput.
*/
int afs_silly_iput(struct dentry *dentry, struct inode *inode)
{
struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
struct afs_vnode *vnode = AFS_FS_I(inode);
struct dentry *alias;
int ret;
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
_enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
down_read(&dvnode->rmdir_lock);
alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
if (IS_ERR(alias)) {
up_read(&dvnode->rmdir_lock);
return 0;
}
if (!d_in_lookup(alias)) {
/* We raced with lookup... See if we need to transfer the
* sillyrename information to the aliased dentry.
*/
ret = 0;
spin_lock(&alias->d_lock);
if (d_really_is_positive(alias) &&
!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
alias->d_flags |= DCACHE_NFSFS_RENAMED;
ret = 1;
}
spin_unlock(&alias->d_lock);
up_read(&dvnode->rmdir_lock);
dput(alias);
return ret;
}
/* Stop lock-release from complaining. */
spin_lock(&vnode->lock);
vnode->lock_state = AFS_VNODE_LOCK_DELETED;
trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
spin_unlock(&vnode->lock);
afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
up_read(&dvnode->rmdir_lock);
d_lookup_done(alias);
dput(alias);
return 1;
}