On 16-Jul 00:59, KP Singh wrote:
> On 15-Jul 14:57, Martin KaFai Lau wrote:
> > On Thu, Jul 09, 2020 at 12:12:37PM +0200, KP Singh wrote:
> > > From: KP Singh <kpsingh@xxxxxxxxxx>
> > >
> > > Similar to bpf_local_storage for sockets, add local storage for inodes.
> > > The life-cycle of storage is managed with the life-cycle of the inode.
> > > i.e. the storage is destroyed along with the owning inode.
> > >
> > > The BPF LSM allocates an __rcu pointer to the bpf_local_storage in the
> > > security blob which are now stackable and can co-exist with other LSMs.
> > >
> > > Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
> >
> > [ ... ]
> >
> >
> > > +static void *bpf_inode_storage_lookup_elem(struct bpf_map *map, void *key)
> > > +{
> > > + struct bpf_local_storage_data *sdata;
> > > + struct inode *inode;
> > > + int err = -EINVAL;
> > > +
> > > + if (key) {
> > > + inode = *(struct inode **)(key);
> > The bpf_inode_storage_lookup_elem() here and the (update|delete)_elem() below
> > are called from the userspace syscall. How the userspace may provide this key?
>
> I realized this when I replied about the _fd_ name in the sk helpers.
> I am going to mark them as unsupported for now for inodes.
>
> We could, probably and separately, use a combination of the device
> and inode number as a key from userspace.
I actually implemented these as:
static int bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
{
struct file *f;
int fd;
fd = *(int *)key;
f = fcheck(fd);
if (!f)
return -EINVAL;
return inode_storage_delete(f->f_inode, map);
}
This keeps it similar to sk_storage and the userspace can just pass an
fd.
- KP
>
> - KP
>
> >
> > > + sdata = inode_storage_lookup(inode, map, true);
> > > + return sdata ? sdata->data : NULL;
> > > + }
> > > +
> > > + return ERR_PTR(err);
> > > +}
> > > +
> > > +static int bpf_inode_storage_update_elem(struct bpf_map *map, void *key,
> > > + void *value, u64 map_flags)
> > > +{
> > > + struct bpf_local_storage_data *sdata;
> > > + struct inode *inode;
> > > + int err = -EINVAL;
> > > +
> > > + if (key) {
> > > + inode = *(struct inode **)(key);
> > > + sdata = map->ops->map_local_storage_update(inode, map, value,
> > > + map_flags);
> > > + return PTR_ERR_OR_ZERO(sdata);
> > > + }
> > > + return err;
> > > +}
> > > +
> > > +static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
> > > +{
> > > + struct bpf_local_storage_data *sdata;
> > > +
> > > + sdata = inode_storage_lookup(inode, map, false);
> > > + if (!sdata)
> > > + return -ENOENT;
> > > +
> > > + bpf_selem_unlink_map_elem(SELEM(sdata));
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int bpf_inode_storage_delete_elem(struct bpf_map *map, void *key)
> > > +{
> > > + struct inode *inode;
> > > + int err = -EINVAL;
> > > +
> > > + if (key) {
> > > + inode = *(struct inode **)(key);
> > > + err = inode_storage_delete(inode, map);
> > > + }
> > > +
> > > + return err;
> > > +}
> > > +
> >
> > [ ... ]
> >
> > > +static int inode_storage_map_btf_id;
> > > +const struct bpf_map_ops inode_storage_map_ops = {
> > > + .map_alloc_check = bpf_local_storage_map_alloc_check,
> > > + .map_alloc = inode_storage_map_alloc,
> > > + .map_free = inode_storage_map_free,
> > > + .map_get_next_key = notsupp_get_next_key,
> > > + .map_lookup_elem = bpf_inode_storage_lookup_elem,
> > > + .map_update_elem = bpf_inode_storage_update_elem,
> > > + .map_delete_elem = bpf_inode_storage_delete_elem,
> > > + .map_check_btf = bpf_local_storage_map_check_btf,
> > > + .map_btf_name = "bpf_local_storage_map",
> > > + .map_btf_id = &inode_storage_map_btf_id,
> > > + .map_local_storage_alloc = inode_storage_alloc,
> > > + .map_selem_alloc = inode_selem_alloc,
> > > + .map_local_storage_update = inode_storage_update,
> > > + .map_local_storage_unlink = unlink_inode_storage,
> > > +};
> > > +
