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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: David Howells <dhowells@redhat.com>
Tested-by: Markus 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/
This commit is contained in:
David Howells 2021-09-01 19:22:50 +01:00
parent 581b2027af
commit 3978d81652
3 changed files with 41 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/afs/dir.c
View File

@ -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;

16
fs/afs/file.c
View File

@ -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);
}

17
fs/afs/write.c
View File

@ -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