docs: networking: convert xfrm_device.txt to ReST

- add SPDX header;
- mark code blocks and literals as such;
- mark tables as such;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mauro Carvalho Chehab 2020-05-01 16:44:29 +02:00 committed by David S. Miller
parent c4ea03fdfd
commit c4a0eb9350
2 changed files with 23 additions and 11 deletions

View File

@ -117,6 +117,7 @@ Contents:
vxlan
x25-iface
x25
xfrm_device
.. only:: subproject and html

View File

@ -1,7 +1,9 @@
.. SPDX-License-Identifier: GPL-2.0
===============================================
XFRM device - offloading the IPsec computations
===============================================
Shannon Nelson <shannon.nelson@oracle.com>
@ -19,7 +21,7 @@ hardware offload.
Userland access to the offload is typically through a system such as
libreswan or KAME/raccoon, but the iproute2 'ip xfrm' command set can
be handy when experimenting. An example command might look something
like this:
like this::
ip x s add proto esp dst 14.0.0.70 src 14.0.0.52 spi 0x07 mode transport \
reqid 0x07 replay-window 32 \
@ -34,15 +36,17 @@ Yes, that's ugly, but that's what shell scripts and/or libreswan are for.
Callbacks to implement
======================
/* from include/linux/netdevice.h */
struct xfrmdev_ops {
::
/* from include/linux/netdevice.h */
struct xfrmdev_ops {
int (*xdo_dev_state_add) (struct xfrm_state *x);
void (*xdo_dev_state_delete) (struct xfrm_state *x);
void (*xdo_dev_state_free) (struct xfrm_state *x);
bool (*xdo_dev_offload_ok) (struct sk_buff *skb,
struct xfrm_state *x);
void (*xdo_dev_state_advance_esn) (struct xfrm_state *x);
};
};
The NIC driver offering ipsec offload will need to implement these
callbacks to make the offload available to the network stack's
@ -58,6 +62,8 @@ At probe time and before the call to register_netdev(), the driver should
set up local data structures and XFRM callbacks, and set the feature bits.
The XFRM code's listener will finish the setup on NETDEV_REGISTER.
::
adapter->netdev->xfrmdev_ops = &ixgbe_xfrmdev_ops;
adapter->netdev->features |= NETIF_F_HW_ESP;
adapter->netdev->hw_enc_features |= NETIF_F_HW_ESP;
@ -65,16 +71,20 @@ The XFRM code's listener will finish the setup on NETDEV_REGISTER.
When new SAs are set up with a request for "offload" feature, the
driver's xdo_dev_state_add() will be given the new SA to be offloaded
and an indication of whether it is for Rx or Tx. The driver should
- verify the algorithm is supported for offloads
- store the SA information (key, salt, target-ip, protocol, etc)
- enable the HW offload of the SA
- return status value:
=========== ===================================
0 success
-EOPNETSUPP offload not supported, try SW IPsec
other fail the request
=========== ===================================
The driver can also set an offload_handle in the SA, an opaque void pointer
that can be used to convey context into the fast-path offload requests.
that can be used to convey context into the fast-path offload requests::
xs->xso.offload_handle = context;
@ -88,7 +98,7 @@ return true of false to signify its support.
When ready to send, the driver needs to inspect the Tx packet for the
offload information, including the opaque context, and set up the packet
send accordingly.
send accordingly::
xs = xfrm_input_state(skb);
context = xs->xso.offload_handle;
@ -105,18 +115,21 @@ the packet's skb. At this point the data should be decrypted but the
IPsec headers are still in the packet data; they are removed later up
the stack in xfrm_input().
find and hold the SA that was used to the Rx skb
find and hold the SA that was used to the Rx skb::
get spi, protocol, and destination IP from packet headers
xs = find xs from (spi, protocol, dest_IP)
xfrm_state_hold(xs);
store the state information into the skb
store the state information into the skb::
sp = secpath_set(skb);
if (!sp) return;
sp->xvec[sp->len++] = xs;
sp->olen++;
indicate the success and/or error status of the offload
indicate the success and/or error status of the offload::
xo = xfrm_offload(skb);
xo->flags = CRYPTO_DONE;
xo->status = crypto_status;
@ -136,5 +149,3 @@ hardware needs.
As a netdev is set to DOWN the XFRM stack's netdev listener will call
xdo_dev_state_delete() and xdo_dev_state_free() on any remaining offloaded
states.