Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 183 insertions, 0 deletions

diff --git a/Documentation/networking/psp.rst b/Documentation/networking/psp.rst
new file mode 100644
index 000000000..4ac09e64e
--- /dev/null
+++ b/Documentation/networking/psp.rst
@@ -0,0 +1,183 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=====================
+PSP Security Protocol
+=====================
+
+Protocol
+========
+
+PSP Security Protocol (PSP) was defined at Google and published in:
+
+https://raw.githubusercontent.com/google/psp/main/doc/PSP_Arch_Spec.pdf
+
+This section briefly covers protocol aspects crucial for understanding
+the kernel API. Refer to the protocol specification for further details.
+
+Note that the kernel implementation and documentation uses the term
+"device key" in place of "master key", it is both less confusing
+to an average developer and is less likely to run afoul any naming
+guidelines.
+
+Derived Rx keys
+---------------
+
+PSP borrows some terms and mechanisms from IPsec. PSP was designed
+with HW offloads in mind. The key feature of PSP is that Rx keys for every
+connection do not have to be stored by the receiver but can be derived
+from device key and information present in packet headers.
+This makes it possible to implement receivers which require a constant
+amount of memory regardless of the number of connections (``O(1)`` scaling).
+
+Tx keys have to be stored like with any other protocol, but Tx is much
+less latency sensitive than Rx, and delays in fetching keys from slow
+memory is less likely to cause packet drops. Preferably, the Tx keys
+should be provided with the packet (e.g. as part of the descriptors).
+
+Key rotation
+------------
+
+The device key known only to the receiver is fundamental to the design.
+Per specification this state cannot be directly accessible (it must be
+impossible to read it out of the hardware of the receiver NIC).
+Moreover, it has to be "rotated" periodically (usually daily). Rotation
+means that new device key gets generated (by a random number generator
+of the device), and used for all new connections. To avoid disrupting
+old connections the old device key remains in the NIC. A phase bit
+carried in the packet headers indicates which generation of device key
+the packet has been encrypted with.
+
+User facing API
+===============
+
+PSP is designed primarily for hardware offloads. There is currently
+no software fallback for systems which do not have PSP capable NICs.
+There is also no standard (or otherwise defined) way of establishing
+a PSP-secured connection or exchanging the symmetric keys.
+
+The expectation is that higher layer protocols will take care of
+protocol and key negotiation. For example one may use TLS key exchange,
+announce the PSP capability, and switch to PSP if both endpoints
+are PSP-capable.
+
+All configuration of PSP is performed via the PSP netlink family.
+
+Device discovery
+----------------
+
+The PSP netlink family defines operations to retrieve information
+about the PSP devices available on the system, configure them and
+access PSP related statistics.
+
+Securing a connection
+---------------------
+
+PSP encryption is currently only supported for TCP connections.
+Rx and Tx keys are allocated separately. First the ``rx-assoc``
+Netlink command needs to be issued, specifying a target TCP socket.
+Kernel will allocate a new PSP Rx key from the NIC and associate it
+with given socket. At this stage socket will accept both PSP-secured
+and plain text TCP packets.
+
+Tx keys are installed using the ``tx-assoc`` Netlink command.
+Once the Tx keys are installed, all data read from the socket will
+be PSP-secured. In other words act of installing Tx keys has a secondary
+effect on the Rx direction.
+
+There is an intermediate period after ``tx-assoc`` successfully
+returns and before the TCP socket encounters it's first PSP
+authenticated packet, where the TCP stack will allow certain nondata
+packets, i.e. ACKs, FINs, and RSTs, to enter TCP receive processing
+even if not PSP authenticated. During the ``tx-assoc`` call, the TCP
+socket's ``rcv_nxt`` field is recorded. At this point, ACKs and RSTs
+will be accepted with any sequence number, while FINs will only be
+accepted at the latched value of ``rcv_nxt``. Once the TCP stack
+encounters the first TCP packet containing PSP authenticated data, the
+other end of the connection must have executed the ``tx-assoc``
+command, so any TCP packet, including those without data, will be
+dropped before receive processing if it is not successfully
+authenticated. This is summarized in the table below. The
+aforementioned state of rejecting all non-PSP packets is labeled "PSP
+Full".
+
++----------------+------------+------------+-------------+-------------+
+| Event          | Normal TCP | Rx PSP     | Tx PSP      | PSP Full    |
++================+============+============+=============+=============+
+| Rx plain       | accept     | accept     | drop        | drop        |
+| (data)         |            |            |             |             |
++----------------+------------+------------+-------------+-------------+
+| Rx plain       | accept     | accept     | accept      | drop        |
+| (ACK|FIN|RST)  |            |            |             |             |
++----------------+------------+------------+-------------+-------------+
+| Rx PSP (good)  | drop       | accept     | accept      | accept      |
++----------------+------------+------------+-------------+-------------+
+| Rx PSP (bad    | drop       | drop       | drop        | drop        |
+| crypt, !=SPI)  |            |            |             |             |
++----------------+------------+------------+-------------+-------------+
+| Tx             | plain text | plain text | encrypted   | encrypted   |
+|                |            |            | (excl. rtx) | (excl. rtx) |
++----------------+------------+------------+-------------+-------------+
+
+To ensure that any data read from the socket after the ``tx-assoc``
+call returns success has been authenticated, the kernel will scan the
+receive and ofo queues of the socket at ``tx-assoc`` time. If any
+enqueued packet was received in clear text, the Tx association will
+fail, and the application should retry installing the Tx key after
+draining the socket (this should not be necessary if both endpoints
+are well behaved).
+
+Because TCP sequence numbers are not integrity protected prior to
+upgrading to PSP, it is possible that a MITM could offset sequence
+numbers in a way that deletes a prefix of the PSP protected part of
+the TCP stream. If userspace cares to mitigate this type of attack, a
+special "start of PSP" message should be exchanged after ``tx-assoc``.
+
+Rotation notifications
+----------------------
+
+The rotations of device key happen asynchronously and are usually
+performed by management daemons, not under application control.
+The PSP netlink family will generate a notification whenever keys
+are rotated. The applications are expected to re-establish connections
+before keys are rotated again.
+
+Kernel implementation
+=====================
+
+Driver notes
+------------
+
+Drivers are expected to start with no PSP enabled (``psp-versions-ena``
+in ``dev-get`` set to ``0``) whenever possible. The user space should
+not depend on this behavior, as future extension may necessitate creation
+of devices with PSP already enabled, nonetheless drivers should not enable
+PSP by default. Enabling PSP should be the responsibility of the system
+component which also takes care of key rotation.
+
+Note that ``psp-versions-ena`` is expected to be used only for enabling
+receive processing. The device is not expected to reject transmit requests
+after ``psp-versions-ena`` has been disabled. User may also disable
+``psp-versions-ena`` while there are active associations, which will
+break all PSP Rx processing.
+
+Drivers are expected to ensure that a device key is usable and secure
+upon init, without explicit key rotation by the user space. It must be
+possible to allocate working keys, and that no duplicate keys must be
+generated. If the device allows the host to request the key for an
+arbitrary SPI - driver should discard both device keys (rotate the
+device key twice), to avoid potentially using a SPI+key which previous
+OS instance already had access to.
+
+Drivers must use ``psp_skb_get_assoc_rcu()`` to check if PSP Tx offload
+was requested for given skb. On Rx drivers should allocate and populate
+the ``SKB_EXT_PSP`` skb extension, and set the skb->decrypted bit to 1.
+
+Kernel implementation notes
+---------------------------
+
+PSP implementation follows the TLS offload more closely than the IPsec
+offload, with per-socket state, and the use of skb->decrypted to prevent
+clear text leaks.
+
+PSP device is separate from netdev, to make it possible to "delegate"
+PSP offload capabilities to software devices (e.g. ``veth``).