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Toke Høiland-Jørgensen 92234c8f15 xdp: Support specifying expected existing program when attaching XDP
While it is currently possible for userspace to specify that an existing
XDP program should not be replaced when attaching to an interface, there is
no mechanism to safely replace a specific XDP program with another.

This patch adds a new netlink attribute, IFLA_XDP_EXPECTED_FD, which can be
set along with IFLA_XDP_FD. If set, the kernel will check that the program
currently loaded on the interface matches the expected one, and fail the
operation if it does not. This corresponds to a 'cmpxchg' memory operation.
Setting the new attribute with a negative value means that no program is
expected to be attached, which corresponds to setting the UPDATE_IF_NOEXIST
flag.

A new companion flag, XDP_FLAGS_REPLACE, is also added to explicitly
request checking of the EXPECTED_FD attribute. This is needed for userspace
to discover whether the kernel supports the new attribute.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/158515700640.92963.3551295145441017022.stgit@toke.dk
2020-03-28 14:24:41 -07:00
arch bpf: Support llvm-objcopy for vmlinux BTF 2020-03-19 12:32:38 +01:00
block block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group() 2020-03-06 07:00:58 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation bpf: Document bpf_inspect drgn tool 2020-03-26 00:08:36 +01:00
drivers sfc: fix XDP-redirect in this driver 2020-03-16 18:22:43 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
include xdp: Support specifying expected existing program when attaching XDP 2020-03-28 14:24:41 -07:00
init Tracing updates: 2020-02-26 10:34:42 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel bpf: Enable bpf cgroup hooks to retrieve cgroup v2 and ancestor id 2020-03-27 19:40:39 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-02-29 15:53:35 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 16:19:19 -07:00
net xdp: Support specifying expected existing program when attaching XDP 2020-03-28 14:24:41 -07:00
samples samples, bpf: Refactor perf_event user program with libbpf bpf_link 2020-03-23 22:27:57 +01:00
scripts bpf: Support llvm-objcopy for vmlinux BTF 2020-03-19 12:32:38 +01:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
sound Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 22:34:48 -07:00
tools libbpf, xsk: Init all ring members in xsk_umem__create and xsk_socket__create 2020-03-28 17:12:56 +01:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM/arm fixes for 5.6, take #1 2020-02-28 11:50:06 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2020-03-06 21:50:05 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore selftest/lkdtm: Use local .gitignore 2020-03-02 08:39:39 -07:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-03-13 20:52:03 -07:00
Makefile Linux 5.6-rc5 2020-03-08 17:44:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.