linux-toradex.git/net/tls/tls_device_fallback.c, branch v5.18

net/tls: Fix use-after-free after the TLS device goes down and up

2021-06-01T22:58:05+00:00

When a netdev with active TLS offload goes down, tls_device_down is
called to stop the offload and tear down the TLS context. However, the
socket stays alive, and it still points to the TLS context, which is now
deallocated. If a netdev goes up, while the connection is still active,
and the data flow resumes after a number of TCP retransmissions, it will
lead to a use-after-free of the TLS context.

This commit addresses this bug by keeping the context alive until its
normal destruction, and implements the necessary fallbacks, so that the
connection can resume in software (non-offloaded) kTLS mode.

On the TX side tls_sw_fallback is used to encrypt all packets. The RX
side already has all the necessary fallbacks, because receiving
non-decrypted packets is supported. The thing needed on the RX side is
to block resync requests, which are normally produced after receiving
non-decrypted packets.

The necessary synchronization is implemented for a graceful teardown:
first the fallbacks are deployed, then the driver resources are released
(it used to be possible to have a tls_dev_resync after tls_dev_del).

A new flag called TLS_RX_DEV_DEGRADED is added to indicate the fallback
mode. It's used to skip the RX resync logic completely, as it becomes
useless, and some objects may be released (for example, resync_async,
which is allocated and freed by the driver).

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Maxim Mikityanskiy 
Reviewed-by: Tariq Toukan 
Signed-off-by: David S. Miller

net/tls: Except bond interface from some TLS checks

2021-01-19T04:48:40+00:00

In the tls_dev_event handler, ignore tlsdev_ops requirement for bond
interfaces, they do not exist as the interaction is done directly with
the lower device.

Also, make the validate function pass when it's called with the upper
bond interface.

Signed-off-by: Tariq Toukan 
Reviewed-by: Boris Pismenny 
Signed-off-by: Jakub Kicinski

net/tls: make inline helpers protocol-aware

2020-11-27T22:32:37+00:00

Inline functions defined in tls.h have a lot of AES-specific
constants. Remove these constants and change argument to struct
tls_prot_info to have an access to cipher type in later patches

Signed-off-by: Vadim Fedorenko 
Signed-off-by: Jakub Kicinski

net: Use skb_frag_off accessors

2019-07-30T21:21:32+00:00

Use accessor functions for skb fragment's page_offset instead
of direct references, in preparation for bvec conversion.

Signed-off-by: Jonathan Lemon 
Signed-off-by: David S. Miller

net/tls: fix socket wmem accounting on fallback with netem

2019-07-09T03:21:10+00:00

netem runs skb_orphan_partial() which "disconnects" the skb
from normal TCP write memory accounting.  We should not adjust
sk->sk_wmem_alloc on the fallback path for such skbs.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: David S. Miller

net/tls: export TLS per skb encryption

2019-06-06T21:13:40+00:00

While offloading TLS connections, drivers need to handle the case where
out of order packets need to be transmitted.

Other drivers obtain the entire TLS record for the specific skb to
provide as context to hardware for encryption. However, other designs
may also want to keep the hardware state intact and perform the
out of order encryption entirely on the host.

To achieve this, export the already existing software encryption
fallback path so drivers could access this.

Signed-off-by: Dirk van der Merwe 
Reviewed-by: Jakub Kicinski 
Signed-off-by: David S. Miller

net/tls: remove false positive warning

2019-06-04T21:33:50+00:00

It's possible that TCP stack will decide to retransmit a packet
right when that packet's data gets acked, especially in presence
of packet reordering.  This means that packets may be in flight,
even though tls_device code has already freed their record state.
Make fill_sg_in() and in turn tls_sw_fallback() not generate a
warning in that case, and quietly proceed to drop such frames.

Make the exit path from tls_sw_fallback() drop monitor friendly,
for users to be able to troubleshoot dropped retransmissions.

Signed-off-by: Jakub Kicinski 
Reviewed-by: Dirk van der Merwe 
Signed-off-by: David S. Miller

net/tls: avoid NULL pointer deref on nskb->sk in fallback

2019-05-01T15:37:56+00:00

update_chksum() accesses nskb->sk before it has been set
by complete_skb(), move the init up.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Jakub Kicinski 
Reviewed-by: Simon Horman 
Signed-off-by: David S. Miller

net/tls: fix refcount adjustment in fallback

2019-04-18T23:51:03+00:00

Unlike atomic_add(), refcount_add() does not deal well
with a negative argument.  TLS fallback code reallocates
the skb and is very likely to shrink the truesize, leading to:

[  189.513254] WARNING: CPU: 5 PID: 0 at lib/refcount.c:81 refcount_add_not_zero_checked+0x15c/0x180
 Call Trace:
  refcount_add_checked+0x6/0x40
  tls_enc_skb+0xb93/0x13e0 [tls]

Once wmem_allocated count saturates the application can no longer
send data on the socket.  This is similar to Eric's fixes for GSO,
TCP:
commit 7ec318feeed1 ("tcp: gso: avoid refcount_t warning from tcp_gso_segment()")
and UDP:
commit 575b65bc5bff ("udp: avoid refcount_t saturation in __udp_gso_segment()").

Unlike the GSO case, for TLS fallback it's likely that the skb has
shrunk, so the "likely" annotation is the other way around (likely
branch being "sub").

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Jakub Kicinski 
Reviewed-by: John Hurley 
Signed-off-by: David S. Miller

net: tls: Add tls 1.3 support

2019-02-01T23:00:55+00:00

TLS 1.3 has minor changes from TLS 1.2 at the record layer.

* Header now hardcodes the same version and application content type in
  the header.
* The real content type is appended after the data, before encryption (or
  after decryption).
* The IV is xored with the sequence number, instead of concatinating four
  bytes of IV with the explicit IV.
* Zero-padding:  No exlicit length is given, we search backwards from the
  end of the decrypted data for the first non-zero byte, which is the
  content type.  Currently recv supports reading zero-padding, but there
  is no way for send to add zero padding.

Signed-off-by: Dave Watson 
Signed-off-by: David S. Miller