Commit 3978d816 authored by David Howells's avatar David Howells
Browse files

afs: Add missing vnode validation checks 



afs_d_revalidate() should only be validating the directory entry it is
given and the directory to which that belongs; it shouldn't be validating
the inode/vnode to which that dentry points.  Besides, validation need to
be done even if we don't call afs_d_revalidate() - which might be the case
if we're starting from a file descriptor.

In order for afs_d_revalidate() to be fixed, validation points must be
added in some other places.  Certain directory operations, such as
afs_unlink(), already check this, but not all and not all file operations
either.

Note that the validation of a vnode not only checks to see if the
attributes we have are correct, but also gets a promise from the server to
notify us if that file gets changed by a third party.

Add the following checks:

 - Check the vnode we're going to make a hard link to.
 - Check the vnode we're going to move/rename.
 - Check the vnode we're going to read from.
 - Check the vnode we're going to write to.
 - Check the vnode we're going to sync.
 - Check the vnode we're going to make a mapped page writable for.

Some of these aren't strictly necessary as we're going to perform a server
operation that might get the attributes anyway from which we can determine
if something changed - though it might not get us a callback promise.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Tested-by: default avatarMarkus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/163111667354.283156.12720698333342917516.stgit@warthog.procyon.org.uk/
parent 581b2027

fs/afs/dir.c

+11 −0
Original line number Diff line number Diff line
@@ -1792,6 +1792,10 @@ static int afs_link(struct dentry *from, struct inode *dir, 
		goto error;

	}



	ret = afs_validate(vnode, op->key);

	if (ret < 0)

		goto error_op;



	afs_op_set_vnode(op, 0, dvnode);

	afs_op_set_vnode(op, 1, vnode);

	op->file[0].dv_delta = 1;
@@ -1805,6 +1809,8 @@ static int afs_link(struct dentry *from, struct inode *dir, 
	op->create.reason	= afs_edit_dir_for_link;

	return afs_do_sync_operation(op);



error_op:

	afs_put_operation(op);

error:

	d_drop(dentry);

	_leave(" = %d", ret);
@@ -1989,6 +1995,11 @@ static int afs_rename(struct user_namespace *mnt_userns, struct inode *old_dir, 
	if (IS_ERR(op))

		return PTR_ERR(op);



	ret = afs_validate(vnode, op->key);

	op->error = ret;

	if (ret < 0)

		goto error;



	afs_op_set_vnode(op, 0, orig_dvnode);

	afs_op_set_vnode(op, 1, new_dvnode); /* May be same as orig_dvnode */

	op->file[0].dv_delta = 1;

fs/afs/file.c

+15 −1
Original line number Diff line number Diff line
@@ -24,12 +24,13 @@ static void afs_invalidatepage(struct page *page, unsigned int offset, 
static int afs_releasepage(struct page *page, gfp_t gfp_flags);



static void afs_readahead(struct readahead_control *ractl);

static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);



const struct file_operations afs_file_operations = {

	.open		= afs_open,

	.release	= afs_release,

	.llseek		= generic_file_llseek,

	.read_iter	= generic_file_read_iter,

	.read_iter	= afs_file_read_iter,

	.write_iter	= afs_file_write,

	.mmap		= afs_file_mmap,

	.splice_read	= generic_file_splice_read,
@@ -503,3 +504,16 @@ static int afs_file_mmap(struct file *file, struct vm_area_struct *vma) 
		vma->vm_ops = &afs_vm_ops;

	return ret;

}



static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)

{

	struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));

	struct afs_file *af = iocb->ki_filp->private_data;

	int ret;



	ret = afs_validate(vnode, af->key);

	if (ret < 0)

		return ret;



	return generic_file_read_iter(iocb, iter);

}

fs/afs/write.c

+15 −2
Original line number Diff line number Diff line
@@ -807,6 +807,7 @@ int afs_writepages(struct address_space *mapping, 
ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)

{

	struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));

	struct afs_file *af = iocb->ki_filp->private_data;

	ssize_t result;

	size_t count = iov_iter_count(from);
@@ -822,6 +823,10 @@ ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from) 
	if (!count)

		return 0;



	result = afs_validate(vnode, af->key);

	if (result < 0)

		return result;



	result = generic_file_write_iter(iocb, from);



	_leave(" = %zd", result);
@@ -835,13 +840,18 @@ ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from) 
 */

int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)

{

	struct inode *inode = file_inode(file);

	struct afs_vnode *vnode = AFS_FS_I(inode);

	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));

	struct afs_file *af = file->private_data;

	int ret;



	_enter("{%llx:%llu},{n=%pD},%d",

	       vnode->fid.vid, vnode->fid.vnode, file,

	       datasync);



	ret = afs_validate(vnode, af->key);

	if (ret < 0)

		return ret;



	return file_write_and_wait_range(file, start, end);

}
@@ -855,11 +865,14 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 
	struct file *file = vmf->vma->vm_file;

	struct inode *inode = file_inode(file);

	struct afs_vnode *vnode = AFS_FS_I(inode);

	struct afs_file *af = file->private_data;

	unsigned long priv;

	vm_fault_t ret = VM_FAULT_RETRY;



	_enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);



	afs_validate(vnode, af->key);



	sb_start_pagefault(inode->i_sb);



	/* Wait for the page to be written to the cache before we allow it to