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/
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 66b2352..32a764c 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -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