Andrei Vagin <avagin@xxxxxxxxxxxxx> wrote:
> > > > - mnt = kern_mount_data(&proc_fs_type, ns, 0);
> >
> > Here ns->user_ns and get_current_cred()->user_ns are not always equal
>
> What do you think about the attached patch?
> ...
> - fc = vfs_new_fs_context(&proc_fs_type, NULL, 0,
> - FS_CONTEXT_FOR_KERNEL_MOUNT);
> + fc = vfs_new_fs_context_userns(&proc_fs_type, NULL, 0,
> + FS_CONTEXT_FOR_KERNEL_MOUNT, ns->user_ns);
Or you could just change fc->user_ns immediately after calling
vfs_new_fs_context(). This is what network filesystems should do with
fc->net_ns, for example.
> -struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type,
> +struct fs_context *vfs_new_fs_context_userns(struct file_system_type *fs_type,
> struct dentry *reference,
> unsigned int sb_flags,
> - enum fs_context_purpose purpose)
> + enum fs_context_purpose purpose,
> + struct user_namespace *user_ns)
If you'd really rather add a new parameter, please don't rename the function
to vfs_new_fs_context_userns() - just add a new parameter. There don't need
to be two versions of it.
This brings me to another thought: I want to add the ability to let
namespaces be configured by userspace, for example:
fd = fsopen("nfs");
sprintf(buf, "ns user %d", my_user_ns_fd);
write(fd, buf);
sprintf(buf, "ns net %d", my_net_ns_fd);
write(fd, buf);
write(fd, "s fedoraproject.org:/pub");
write(fd, "o intr");
...
I think therefore, I might need to insert another phase between creating the
context and calling the filesystem initialiser:
fc = vfs_new_fs_context(&afs_fs_type, mntpt, 0,
FS_CONTEXT_FOR_SUBMOUNT);
followed by:
vfs_sb_set_namespace(fc, THIS_IS_USER_NS, user_ns);
vfs_sb_set_namespace(fc, THIS_IS_NET_NS, net_ns);
but then we'd need to do:
vfs_begin_options(fc);
before continuing (unless we made this happen automatically on the receipt of
the first option):
afs_mntpt_set_params(fc, mntpt);
vfs_get_tree(fc);
mnt = vfs_create_mount(fc, 0);
Alternatively, we could do the namespace setting after initialisation and let
the fs apply the changes itself.
David
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