[PATCH 3/6] afs: Add missing vnode validation checks
From: David Howells <dhowells@redhat.com>
Date: 2021-09-08 15:58:08
Also in:
linux-fsdevel
Subsystem:
afs filesystem, filesystems (vfs and infrastructure), the rest · Maintainers:
David Howells, Marc Dionne, Alexander Viro, Christian Brauner, Linus Torvalds
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> cc: linux-afs@lists.infradead.org --- fs/afs/dir.c | 11 +++++++++++ fs/afs/file.c | 16 +++++++++++++++- fs/afs/write.c | 17 +++++++++++++++-- 3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index ac829e63c570..a8e3ae55f1f9 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c@@ -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;
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 6688fff14b0b..4c8d786b53e0 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c@@ -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); +}
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 66b235266893..32a764c24284 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