Messages in this thread | | | From | David Howells <> | Subject | Re: [12/24] proc: Add fs_context support to procfs [ver #7] | Date | Tue, 26 Jun 2018 09:57:07 +0100 |
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Andrei Vagin <avagin@virtuozzo.com> 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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