Add a manpage for kernel TLS.
This subsumes some of the content from tcp(4) describing the socket options but also adds additional notes. Reviewed by: gallatin, hselasky Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D27272
This commit is contained in:
parent
2e51c2bfd1
commit
d1e0552937
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=368040
@ -250,6 +250,7 @@ MAN= aac.4 \
|
||||
kld.4 \
|
||||
ksyms.4 \
|
||||
ksz8995ma.4 \
|
||||
ktls.4 \
|
||||
ktr.4 \
|
||||
kue.4 \
|
||||
lagg.4 \
|
||||
|
264
share/man/man4/ktls.4
Normal file
264
share/man/man4/ktls.4
Normal file
@ -0,0 +1,264 @@
|
||||
.\" Copyright (c) 2020, Chelsio Inc
|
||||
.\" All rights reserved.
|
||||
.\"
|
||||
.\" Redistribution and use in source and binary forms, with or without
|
||||
.\" modification, are permitted provided that the following conditions are met:
|
||||
.\"
|
||||
.\" 1. Redistributions of source code must retain the above copyright notice,
|
||||
.\" this list of conditions and the following disclaimer.
|
||||
.\"
|
||||
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||||
.\" notice, this list of conditions and the following disclaimer in the
|
||||
.\" documentation and/or other materials provided with the distribution.
|
||||
.\"
|
||||
.\" 3. Neither the name of the Chelsio Inc nor the names of its
|
||||
.\" contributors may be used to endorse or promote products derived from
|
||||
.\" this software without specific prior written permission.
|
||||
.\"
|
||||
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||||
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||||
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||||
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||||
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||||
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||||
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||||
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||||
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||||
.\" POSSIBILITY OF SUCH DAMAGE.
|
||||
.\"
|
||||
.\" * Other names and brands may be claimed as the property of others.
|
||||
.\"
|
||||
.\" $FreeBSD$
|
||||
.\"
|
||||
.Dd November 25, 2020
|
||||
.Dt KTLS 4
|
||||
.Os
|
||||
.Sh NAME
|
||||
.Nm ktls
|
||||
.Nd kernel Transport Layer Security
|
||||
.Sh SYNOPSIS
|
||||
.Cd options KERN_TLS
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Nm
|
||||
facility allows the kernel to perform Transport Layer Security (TLS)
|
||||
framing on TCP sockets.
|
||||
With
|
||||
.Nm ,
|
||||
the initial handshake for a socket using TLS is performed in userland.
|
||||
Once the session keys are negotiated,
|
||||
they are provided to the kernel via the
|
||||
.Dv TCP_TXTLS_ENABLE
|
||||
and
|
||||
.Dv TCP_RXTLS_ENABLE
|
||||
socket options.
|
||||
Both socket options accept a
|
||||
.Vt struct tls_so_enable
|
||||
structure as their argument.
|
||||
The members of this structure describe the cipher suite used for the
|
||||
TLS session and provide the session keys used for the respective
|
||||
direction.
|
||||
.Pp
|
||||
.Nm
|
||||
only permits the session keys to be set once in each direction.
|
||||
As a result,
|
||||
applications must disable rekeying when using
|
||||
.Nm .
|
||||
.Ss Modes
|
||||
.Nm
|
||||
can operate in different modes.
|
||||
A given socket may use different modes for transmit and receive,
|
||||
or a socket may only offload a single direction.
|
||||
The available modes are:
|
||||
.Bl -tag -width "Dv TCP_TLS_MODE_IFNET"
|
||||
.It Dv TCP_TLS_MODE_NONE
|
||||
.Nm
|
||||
is not enabled.
|
||||
.It Dv TCP_TLS_MODE_SW
|
||||
TLS records are encrypted or decrypted in the kernel in the socket
|
||||
layer.
|
||||
Typically the encryption or decryption is performred in software,
|
||||
but it may also be performed by co-processors via
|
||||
.Xr crypto 9 .
|
||||
.It Dv TCP_TLS_MODE_IFNET
|
||||
TLS records are encrypted or decrypted by the network interface card (NIC).
|
||||
In this mode, the network stack does not work with encrypted data.
|
||||
Instead, the NIC is encrypts TLS records as they are being transmitted,
|
||||
or decrypts received TLS records before providing them to the host.
|
||||
.Pp
|
||||
Network interfaces which support this feature will advertise the
|
||||
.Dv TXTLS4
|
||||
(for IPv4)
|
||||
and/or
|
||||
.Dv TXTLS6
|
||||
(for IPv6)
|
||||
capabilities as reported by
|
||||
.Xr ifconfig 8 .
|
||||
These capabilities can also be controlled by
|
||||
.Xr ifconfig 8 .
|
||||
.Pp
|
||||
If a network interface supports rate limiting
|
||||
(also known as packet pacing) for TLS offload,
|
||||
the interface will advertise the
|
||||
.Dv TXTLS_RTLMT
|
||||
capability.
|
||||
.It Dv TCP_TLS_MODE_TOE
|
||||
TLS records are encrypted by the NIC using a TCP offload engine (TOE).
|
||||
This is similar to
|
||||
.Dv TCP_TLS_MODE_IFNET
|
||||
in that the network stack does not work with encrypted data.
|
||||
However, this mode works in tandem with a TOE to handle interactions
|
||||
between TCP and TLS.
|
||||
.El
|
||||
.Ss Transmit
|
||||
Once TLS transmit is enabled by a successful set of the
|
||||
.Dv TCP_TXTLS_ENABLE
|
||||
socket option,
|
||||
all data written on the socket is stored in TLS records and encrypted.
|
||||
Most data is transmitted in application layer TLS records,
|
||||
and the kernel chooses how to partition data among TLS records.
|
||||
Individual TLS records with a fixed length and record type can be sent
|
||||
by
|
||||
.Xr sendmsg 2
|
||||
with the TLS record type set in a
|
||||
.Dv TLS_SET_RECORD_TYPE
|
||||
control message.
|
||||
The payload of this control message is a single byte holding the desired
|
||||
TLS record type.
|
||||
This can be used to send TLS records with a type other than
|
||||
application data (for example, handshake messages) or to send
|
||||
application data records with specific contents (for example, empty
|
||||
fragments).
|
||||
.Pp
|
||||
TLS transmit requires the use of unmapped mbufs.
|
||||
Unmapped mbufs are not enabled by default, but can be enabled by
|
||||
setting the
|
||||
.Va kern.ipc.mb_use_ext_pgs
|
||||
sysctl node to 1.
|
||||
.Pp
|
||||
The current TLS transmit mode of a socket can be queried via the
|
||||
.Dv TCP_TXTLS_MODE
|
||||
socket option.
|
||||
A socket using TLS transmit offload can also set the
|
||||
.Dv TCP_TXTLS_MODE
|
||||
socket option to toggle between
|
||||
.Dv TCP_TLS_MODE_SW
|
||||
and
|
||||
.Dv TCP_TLS_MODE_IFNET .
|
||||
.Ss Receive
|
||||
Once TLS receive is enabled by a successful set of the
|
||||
.Dv TCP_RXTLS_ENABLE
|
||||
socket option,
|
||||
all data read from the socket is returned as decrypted TLS records.
|
||||
Each received TLS record must be read from the socket using
|
||||
.Xr recvmsg 2 .
|
||||
Each received TLS record will contain a
|
||||
.Dv TLS_GET_RECORD
|
||||
control message along with the decrypted payload.
|
||||
The control message contains a
|
||||
.Vt struct tls_get_record
|
||||
which includes fields from the TLS record header.
|
||||
If an invalid or corrupted TLS record is received,
|
||||
recvmsg 2
|
||||
will fail with one of the following errors:
|
||||
.Bl -tag -width Er
|
||||
.It Bq Er EINVAL
|
||||
The version fields in a TLS record's header did not match the version required
|
||||
by the
|
||||
.Vt struct tls_so_enable
|
||||
structure used to enable in-kernel TLS.
|
||||
.It Bq Er EMSGSIZE
|
||||
A TLS record's length was either too small or too large.
|
||||
.It Bq Er EMSGSIZE
|
||||
The connection was closed after sending a truncated TLS record.
|
||||
.It Bq Er EBADMSG
|
||||
The TLS record failed to match the included authentication tag.
|
||||
.El
|
||||
.Pp
|
||||
The current TLS receive mode of a socket can be queried via the
|
||||
.Dv TCP_RXTLS_MODE
|
||||
socket option.
|
||||
At present,
|
||||
the mode cannot be changed.
|
||||
.Ss Sysctl Nodes
|
||||
.Nm
|
||||
uses several sysctl nodes under the
|
||||
.Va kern.ipc.tls
|
||||
node.
|
||||
A few of them are described below:
|
||||
.Bl -tag -width ".Va kern.ipc.tls.cbc_enable"
|
||||
.It Va kern.ipc.tls.enable
|
||||
Determines if new kernel TLS sessions can be created.
|
||||
.It Va kern.ipc.tls.cbc_enable
|
||||
Determines if new kernel TLS sessions with a cipher suite using AES-CBC
|
||||
can be created.
|
||||
.It Va kern.ipc.tls.sw
|
||||
A tree of nodes containing statistics for TLS sessions using
|
||||
.Dv TCP_TLS_MODE_SW .
|
||||
.It Va kern.ipc.tls.ifnet
|
||||
A tree of nodes containing statistics for TLS sessions using
|
||||
.Dv TCP_TLS_MODE_IFNET .
|
||||
.It Va kern.ipc.tls.toe
|
||||
A tree of nodes containing statistics for TLS sessions using
|
||||
.Dv TCP_TLS_MODE_TOE .
|
||||
.It Va kern.ipc.tls.stats
|
||||
A tree of nodes containing various kernel TLS statistics.
|
||||
.El
|
||||
.Ss Backends
|
||||
The base system includes a software backend for the
|
||||
.Dv TCP_TLS_MODE_SW
|
||||
mode which uses
|
||||
.Xr crypto 9
|
||||
to encrypt and decrypt TLS records.
|
||||
This backend can be enabled by loading the
|
||||
.Pa ktls_ocf.ko
|
||||
kernel module.
|
||||
.Pp
|
||||
The
|
||||
.Xr cxgbe 4
|
||||
and
|
||||
.Xr mlx5en 4
|
||||
drivers include support for the
|
||||
.Dv TCP_TLS_MODE_IFNET
|
||||
mode.
|
||||
.Pp
|
||||
The
|
||||
.Xr cxgbe 4
|
||||
driver includes support for the
|
||||
.Dv TCP_TLS_MODE_TOE
|
||||
mode.
|
||||
.Ss Supported Libraries
|
||||
OpenSSL 3.0 and later include support for
|
||||
.Nm .
|
||||
The
|
||||
.Fa devel/openssl
|
||||
port may also be built with support for
|
||||
.Nm
|
||||
by enabling the
|
||||
.Dv KTLS
|
||||
option .
|
||||
.Pp
|
||||
Applications using a supported library should generally work with
|
||||
.Nm
|
||||
without any changes provided they use standard interfaces such as
|
||||
.Xr SSL_read 3
|
||||
and
|
||||
.Xr SSL_write 3 .
|
||||
Additional performance may be gained by the use of
|
||||
.Xr SSL_sendfile 3 .
|
||||
.Sh IMPLEMENTATION NOTES
|
||||
.Nm
|
||||
assumes the presence of a direct map of physical memory when performing
|
||||
software encryption and decryption.
|
||||
As a result, it is only supported on architectures with a direct map.
|
||||
.Sh SEE ALSO
|
||||
.Xr cxgbe 4 ,
|
||||
.Xr mlx5en 4 ,
|
||||
.Xr tcp 4 ,
|
||||
.Xr ifconfig 8 ,
|
||||
.Xr sysctl 8 ,
|
||||
.Xr crypto 9
|
||||
.Sh HISTORY
|
||||
Kernel TLS first appeared in
|
||||
.Fx 13.0 .
|
@ -34,7 +34,7 @@
|
||||
.\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93
|
||||
.\" $FreeBSD$
|
||||
.\"
|
||||
.Dd July 23, 2020
|
||||
.Dd November 25, 2020
|
||||
.Dt TCP 4
|
||||
.Os
|
||||
.Sh NAME
|
||||
@ -300,86 +300,20 @@ Each dropped segment is taken into account in the TCP protocol statistics.
|
||||
.It Dv TCP_TXTLS_ENABLE
|
||||
Enable in-kernel Transport Layer Security (TLS) for data written to this
|
||||
socket.
|
||||
The
|
||||
.Vt struct tls_so_enable
|
||||
argument defines the encryption and authentication algorithms and keys
|
||||
used to encrypt the socket data as well as the maximum TLS record
|
||||
payload size.
|
||||
.Pp
|
||||
All data written to this socket will be encapsulated in TLS records
|
||||
and subsequently encrypted.
|
||||
By default all data written to this socket is treated as application data.
|
||||
Individual TLS records with a type other than application data
|
||||
(for example, handshake messages),
|
||||
may be transmitted by invoking
|
||||
.Xr sendmsg 2
|
||||
with a custom TLS record type set in a
|
||||
.Dv TLS_SET_RECORD_TYPE
|
||||
control message.
|
||||
The payload of this control message is a single byte holding the desired
|
||||
TLS record type.
|
||||
.Pp
|
||||
At present, only a single transmit key may be set on a socket.
|
||||
As such, users of this option must disable rekeying.
|
||||
See
|
||||
.Xr ktls 4
|
||||
for more details.
|
||||
.It Dv TCP_TXTLS_MODE
|
||||
The integer argument can be used to get or set the current TLS transmit mode
|
||||
of a socket.
|
||||
Setting the mode can only used to toggle between software and NIC TLS after
|
||||
TLS has been initially enabled via the
|
||||
.Dv TCP_TXTLS_ENABLE
|
||||
option.
|
||||
The available modes are:
|
||||
.Bl -tag -width "Dv TCP_TLS_MODE_IFNET"
|
||||
.It Dv TCP_TLS_MODE_NONE
|
||||
In-kernel TLS framing and encryption is not enabled for this socket.
|
||||
.It Dv TCP_TLS_MODE_SW
|
||||
TLS records are encrypted by the kernel prior to placing the data in the
|
||||
socket buffer.
|
||||
Typically this encryption is performed in software.
|
||||
.It Dv TCP_TLS_MODE_IFNET
|
||||
TLS records are encrypted by the network interface card (NIC).
|
||||
.It Dv TCP_TLS_MODE_TOE
|
||||
TLS records are encrypted by the NIC using a TCP offload engine (TOE).
|
||||
.El
|
||||
See
|
||||
.Xr ktls 4
|
||||
for more details.
|
||||
.It Dv TCP_RXTLS_ENABLE
|
||||
Enable in-kernel TLS for data read from this socket.
|
||||
The
|
||||
.Vt struct tls_so_enable
|
||||
argument defines the encryption and authentication algorithms and keys
|
||||
used to decrypt the socket data.
|
||||
.Pp
|
||||
Each received TLS record must be read from the socket using
|
||||
.Xr recvmsg 2 .
|
||||
Each received TLS record will contain a
|
||||
.Dv TLS_GET_RECORD
|
||||
control message along with the decrypted payload.
|
||||
The control message contains a
|
||||
.Vt struct tls_get_record
|
||||
which includes fields from the TLS record header.
|
||||
If an invalid or corrupted TLS record is received,
|
||||
recvmsg 2
|
||||
will fail with one of the following errors:
|
||||
.Bl -tag -width Er
|
||||
.It Bq Er EINVAL
|
||||
The version fields in a TLS record's header did not match the version required
|
||||
by the
|
||||
.Vt struct tls_so_enable
|
||||
structure used to enable in-kernel TLS.
|
||||
.It Bq Er EMSGSIZE
|
||||
A TLS record's length was either too small or too large.
|
||||
.It Bq Er EMSGSIZE
|
||||
The connection was closed after sending a truncated TLS record.
|
||||
.It Bq Er EBADMSG
|
||||
The TLS record failed to match the included authentication tag.
|
||||
.El
|
||||
.Pp
|
||||
At present, only a single receive key may be set on a socket.
|
||||
As such, users of this option must disable rekeying.
|
||||
.It Dv TCP_RXTLS_MODE
|
||||
The integer argument can be used to get the current TLS receive mode
|
||||
of a socket.
|
||||
The available modes are the same as for
|
||||
.Dv TCP_TXTLS_MODE .
|
||||
See
|
||||
.Xr ktls 4
|
||||
for more details.
|
||||
.El
|
||||
.Pp
|
||||
The option level for the
|
||||
@ -770,6 +704,7 @@ when trying to use a TCP function block that is not available;
|
||||
.Xr inet 4 ,
|
||||
.Xr intro 4 ,
|
||||
.Xr ip 4 ,
|
||||
.Xr ktls 4 ,
|
||||
.Xr mod_cc 4 ,
|
||||
.Xr siftr 4 ,
|
||||
.Xr syncache 4 ,
|
||||
|
Loading…
Reference in New Issue
Block a user