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Ira Weiny 3108f7c788 PCI: Allow drivers to request exclusive config regions
[ Upstream commit 278294798a ]

PCI config space access from user space has traditionally been
unrestricted with writes being an understood risk for device operation.

Unfortunately, device breakage or odd behavior from config writes lacks
indicators that can leave driver writers confused when evaluating
failures.  This is especially true with the new PCIe Data Object
Exchange (DOE) mailbox protocol where backdoor shenanigans from user
space through things such as vendor defined protocols may affect device
operation without complete breakage.

A prior proposal restricted read and writes completely.[1]  Greg and
Bjorn pointed out that proposal is flawed for a couple of reasons.
First, lspci should always be allowed and should not interfere with any
device operation.  Second, setpci is a valuable tool that is sometimes
necessary and it should not be completely restricted.[2]  Finally
methods exist for full lock of device access if required.

Even though access should not be restricted it would be nice for driver
writers to be able to flag critical parts of the config space such that
interference from user space can be detected.

Introduce pci_request_config_region_exclusive() to mark exclusive config
regions.  Such regions trigger a warning and kernel taint if accessed
via user space.

Create pci_warn_once() to restrict the user from spamming the log.

[1] https://lore.kernel.org/all/161663543465.1867664.5674061943008380442.stgit@dwillia2-desk3.amr.corp.intel.com/
[2] https://lore.kernel.org/all/YF8NGeGv9vYcMfTV@kroah.com/

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20220926215711.2893286-2-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Stable-dep-of: 5e70d0acf0 ("PCI: Add locking to RMW PCI Express Capability Register accessors")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-09-13 09:42:46 +02:00
arch arm64: dts: qcom: sc8280xp-x13s: Unreserve NC pins 2023-09-13 09:42:43 +02:00
block block/mq-deadline: use correct way to throttling write requests 2023-09-13 09:42:42 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Use work queue in crypto_destroy_instance 2023-09-13 09:42:32 +02:00
Documentation media: uapi: HEVC: Add num_delta_pocs_of_ref_rps_idx field 2023-09-13 09:42:20 +02:00
drivers PCI: Allow drivers to request exclusive config regions 2023-09-13 09:42:46 +02:00
fs ext4: avoid potential data overflow in next_linear_group 2023-09-13 09:42:46 +02:00
include PCI: Allow drivers to request exclusive config regions 2023-09-13 09:42:46 +02:00
init sched/psi: Select KERNFS as needed 2023-09-13 09:42:28 +02:00
io_uring io_uring: fix drain stalls by invalid SQE 2023-09-13 09:42:43 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel PCI: Allow drivers to request exclusive config regions 2023-09-13 09:42:46 +02:00
lib maple_tree: disable mas_wr_append() when other readers are possible 2023-08-30 16:11:13 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm net-memcg: Fix scope of sockmem pressure indicators 2023-09-13 09:42:33 +02:00
net netrom: Deny concurrent connect(). 2023-09-13 09:42:35 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples/bpf: fix broken map lookup probe 2023-09-13 09:42:34 +02:00
scripts kbuild: rust_is_available: fix confusion when a version appears in the path 2023-09-13 09:42:32 +02:00
security smackfs: Prevent underflow in smk_set_cipso() 2023-09-13 09:42:42 +02:00
sound ALSA: ac97: Fix possible error value of *rac97 2023-09-13 09:42:44 +02:00
tools selftests/bpf: Clean up fmod_ret in bench_rename test script 2023-09-13 09:42:33 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile kbuild: rust_is_available: remove -v option 2023-09-13 09:42:32 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.