Add public APIs to parse BTF from raw data file (e.g.,
/sys/kernel/btf/vmlinux), as well as generic btf__parse(), which will try to
determine correct format, currently either raw or ELF.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200802013219.864880-2-andriin@fb.com

In case of btf_id does not exist, a negative error code -ENOENT
should be returned.

Fixes: c93cc690 ("bpftool: add ability to dump BTF types")
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200802111540.5384-1-tianjia.zhang@linux.alibaba.com

The '&&' command seems to have a bad effect when $(cmd_$(1)) exits with
non-zero effect: the command failure is masked (despite `set -e`) and all but
the first command of $(dep-cmd) is executed (successfully, as they are mostly
printfs), thus overall returning 0 in the end.

This means in practice that despite compilation errors, tools's build Makefile
will return success. We see this very reliably with libbpf's Makefile, which
doesn't get compilation error propagated properly. This in turns causes issues
with selftests build, as well as bpftool and other projects that rely on
building libbpf.

The fix is simple: don't use &&. Given `set -e`, we don't need to chain
commands with &&. The shell will exit on first failure, giving desired
behavior and propagating error properly.

Fixes: 275e2d95 ("tools build: Move dependency copy into function")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200731024244.872574-1-andriin@fb.com

core_retro selftest uses BPF program that's triggered on sys_enter
system-wide, but has no protection from some unrelated process doing syscall
while selftest is running. This leads to occasional test failures with
unexpected PIDs being returned. Fix that by filtering out all processes that
are not test_progs process.

Fixes: fcda189a ("selftests/bpf: Add test relying only on CO-RE and no recent kernel features")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731204957.2047119-1-andriin@fb.com

Andrii Nakryiko says:

====================
This patch set adds new BPF link operation, LINK_DETACH, allowing processes
with BPF link FD to force-detach it from respective BPF hook, similarly how
BPF link is auto-detached when such BPF hook (e.g., cgroup, net_device, netns,
etc) is removed. This facility allows admin to forcefully undo BPF link
attachment, while process that created BPF link in the first place is left
intact.

Once force-detached, BPF link stays valid in the kernel as long as there is at
least one FD open against it. It goes into defunct state, just like
auto-detached BPF link.

bpftool also got `link detach` command to allow triggering this in
non-programmatic fashion.

v1->v2:
- improve error reporting in `bpftool link detach` (Song).
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add info on link detach sub-command to man page. Add detach to bash-completion
as well.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com.
Link: https://lore.kernel.org/bpf/20200731182830.286260-6-andriin@fb.com

Add ability to force-detach BPF link. Also add missing error message, if
specified link ID is wrong.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-5-andriin@fb.com

Add bpf_link__detach() testing to selftests for cgroup, netns, and xdp
bpf_links.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-4-andriin@fb.com

Add low-level bpf_link_detach() API. Also add higher-level bpf_link__detach()
one.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-3-andriin@fb.com

Add LINK_DETACH command to force-detach bpf_link without destroying it. It has
the same behavior as auto-detaching of bpf_link due to cgroup dying for
bpf_cgroup_link or net_device being destroyed for bpf_xdp_link. In such case,
bpf_link is still a valid kernel object, but is defuncts and doesn't hold BPF
program attached to corresponding BPF hook. This functionality allows users
with enough access rights to manually force-detach attached bpf_link without
killing respective owner process.

This patch implements LINK_DETACH for cgroup, xdp, and netns links, mostly
re-using existing link release handling code.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200731182830.286260-2-andriin@fb.com

Nearly every user of cgroup helpers does the same sequence of API calls. So
push these into a single helper cgroup_setup_and_join. The cases that do
a bit of extra logic are test_progs which currently uses an env variable
to decide if it needs to setup the cgroup environment or can use an
existingi environment. And then tests that are doing cgroup tests
themselves. We skip these cases for now.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159623335418.30208.15807461815525100199.stgit@john-XPS-13-9370

There exists an error "404 Not Found" when I click the html link of
"Documentation/networking/filter.rst" in the BPF documentation [1],
fix it.

Additionally, use the new links about "BPF and XDP Reference Guide"
and "bpf(2)" to avoid redirects.

[1] https://www.kernel.org/doc/html/latest/bpf/

Fixes: d9b9170a ("docs: bpf: Rename README.rst to index.rst")
Fixes: cb3f0d56 ("docs: networking: convert filter.txt to ReST")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1596184142-18476-1-git-send-email-yangtiezhu@loongson.cn

The o32, n32 and n64 calling conventions require the return
value to be stored in $v0 which maps to $2 register, i.e.,
the register 2.

Fixes: c1932cdb ("bpf: Add MIPS support to samples/bpf.")
Signed-off-by: Jerry Crunchtime <jerry.c.t@web.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/43707d31-0210-e8f0-9226-1af140907641@web.de

When BPF sk lookup invokes reuseport handling for the selected socket, it
should ignore the fact that reuseport group can contain connected UDP
sockets. With BPF sk lookup this is not relevant as we are not scoring
sockets to find the best match, which might be a connected UDP socket.

Fix it by unconditionally accepting the socket selected by reuseport.

This fixes the following two failures reported by test_progs.

  # ./test_progs -t sk_lookup
  ...
  #73/14 UDP IPv4 redir and reuseport with conns:FAIL
  ...
  #73/20 UDP IPv6 redir and reuseport with conns:FAIL
  ...

Fixes: a57066b1 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200726120228.1414348-1-jakub@cloudflare.com

Most of libbpf "constructors" on failure return ERR_PTR(err) result encoded as
a pointer. It's a common mistake to eventually pass such malformed pointers
into xxx__destroy()/xxx__free() "destructors". So instead of fixing up
clean up code in selftests and user programs, handle such error pointers in
destructors themselves. This works beautifully for NULL pointers passed to
destructors, so might as well just work for error pointers.
Suggested-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729232148.896125-1-andriin@fb.com

Setting IFA_F_NODAD flag for IPv6 addresses to add to loopback is
unnecessary. Duplicate Address Detection does not happen on loopback
device.

Also, passing 'nodad' flag to 'ip address' breaks libbpf CI, which runs in
an environment with BusyBox implementation of 'ip' command, that doesn't
understand this flag.

Fixes: 0ab5539f ("selftests/bpf: Tests for BPF_SK_LOOKUP attach point")
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Andrii Nakryiko <andrii@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200730125325.1869363-1-jakub@cloudflare.com

Check that link is NULL or proper pointer before invoking bpf_link__destroy().
Not doing this causes crash in test_progs, when cg_storage_multi selftest
fails.

Fixes: 3573f384 ("selftests/bpf: Test CGROUP_STORAGE behavior on shared egress + ingress")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729045056.3363921-1-andriin@fb.com

This patch add xdpdrv mode for test_xdp_redirect.sh since veth has support
native mode. After update here is the test result:

  # ./test_xdp_redirect.sh
  selftests: test_xdp_redirect xdpgeneric [PASS]
  selftests: test_xdp_redirect xdpdrv [PASS]
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: William Tu <u9012063@gmail.com>
Link: https://lore.kernel.org/bpf/20200729085658.403794-1-liuhangbin@gmail.com

Augment udp_limit test to set and verify socket storage value.
That should be enough to exercise the changes from the previous
patch.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729003104.1280813-2-sdf@google.com

This lets us use socket storage from the following hooks:

* BPF_CGROUP_INET_SOCK_CREATE
* BPF_CGROUP_INET_SOCK_RELEASE
* BPF_CGROUP_INET4_POST_BIND
* BPF_CGROUP_INET6_POST_BIND

Using existing 'bpf_sk_storage_get_proto' doesn't work because
second argument is ARG_PTR_TO_SOCKET. Even though
BPF_PROG_TYPE_CGROUP_SOCK hooks operate on 'struct bpf_sock',
the verifier still considers it as a PTR_TO_CTX.
That's why I'm adding another 'bpf_sk_storage_get_cg_sock_proto'
definition strictly for BPF_PROG_TYPE_CGROUP_SOCK which accepts
ARG_PTR_TO_CTX which is really 'struct sock' for this program type.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729003104.1280813-1-sdf@google.com

Commit afbf21dc ("bpf: Support readonly/readwrite buffers
in verifier") added readonly/readwrite buffer support which
is currently used by bpf_iter tracing programs. It has
a bug with incorrect parameter ordering which later fixed
by Commit f6dfbe31 ("bpf: Fix swapped arguments in calls
to check_buffer_access").

This patch added a test case with a negative offset access
which will trigger the error path.

Without Commit f6dfbe31, running the test case in the patch,
the error message looks like:
   R1_w=rdwr_buf(id=0,off=0,imm=0) R10=fp0
  ; value_sum += *(__u32 *)(value - 4);
  2: (61) r1 = *(u32 *)(r1 -4)
  R1 invalid (null) buffer access: off=-4, size=4

With the above commit, the error message looks like:
   R1_w=rdwr_buf(id=0,off=0,imm=0) R10=fp0
  ; value_sum += *(__u32 *)(value - 4);
  2: (61) r1 = *(u32 *)(r1 -4)
  R1 invalid rdwr buffer access: off=-4, size=4
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200728221801.1090406-1-yhs@fb.com

Newline characters are added in two verifier error messages,
refactored in Commit afbf21dc ("bpf: Support readonly/readwrite
buffers in verifier"). This way, they do not mix with
messages afterwards.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200728221801.1090349-1-yhs@fb.com

When a tracing BPF program attempts to read memory without using the
bpf_probe_read() helper, the verifier marks the load instruction with
the BPF_PROBE_MEM flag. Since the arm64 JIT does not currently recognize
this flag it falls back to the interpreter.

Add support for BPF_PROBE_MEM, by appending an exception table to the
BPF program. If the load instruction causes a data abort, the fixup
infrastructure finds the exception table and fixes up the fault, by
clearing the destination register and jumping over the faulting
instruction.

To keep the compact exception table entry format, inspect the pc in
fixup_exception(). A more generic solution would add a "handler" field
to the table entry, like on x86 and s390.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200728152122.1292756-2-jean-philippe@linaro.org

Entire net/core subsystem is not built without CONFIG_NET. linux/netdevice.h
just assumes that it's always there, so the easiest way to fix this is to
conditionally compile out bpf_xdp_link_attach() use in bpf/syscall.c.

Fixes: aa8d3a71 ("bpf, xdp: Add bpf_link-based XDP attachment API")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200728190527.110830-1-andriin@fb.com

Using localhost requires the host to have a /etc/hosts file with that
specific line in it. By default my dev box did not, they used
ip6-localhost, so the test was failing. To fix remove the need for any
/etc/hosts and use ::1.

I could just add the line, but this seems easier.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159594714197.21431.10113693935099326445.stgit@john-Precision-5820-Tower

xsk_getsockopt() is copying uninitialized stack memory to userspace when
'extra_stats' is 'false'. Fix it. Doing '= {};' is sufficient since currently
'struct xdp_statistics' is defined as follows:

  struct xdp_statistics {
    __u64 rx_dropped;
    __u64 rx_invalid_descs;
    __u64 tx_invalid_descs;
    __u64 rx_ring_full;
    __u64 rx_fill_ring_empty_descs;
    __u64 tx_ring_empty_descs;
  };

When being copied to the userspace, 'stats' will not contain any uninitialized
'holes' between struct fields.

Fixes: 8aa5a335 ("xsk: Add new statistics")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/bpf/20200728053604.404631-1-yepeilin.cs@gmail.com

There are a couple of arguments of the boolean flag zero_size_allowed and
the char pointer buf_info when calling to function check_buffer_access that
are swapped by mistake. Fix these by swapping them to correct the argument
ordering.

Fixes: afbf21dc ("bpf: Support readonly/readwrite buffers in verifier")
Addresses-Coverity: ("Array compared to 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200727175411.155179-1-colin.king@canonical.com

Add bpf_iter__bpf_map_elem and bpf_iter__bpf_sk_storage_map to bpf_iter.h.

Fixes: 3b1c420b ("selftests/bpf: Add a test for bpf sk_storage_map iterator")
Fixes: 2a7c2fff ("selftests/bpf: Add test for bpf hash map iterators")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200727233345.1686358-1-andriin@fb.com

Due to bpf tree fix merge, bpf_ringbuf_output() signature ended up with int as
a return type, while all other helpers got converted to returning long. So fix
it in bpf-next now.

Fixes: b0659d8a ("bpf: Fix definition of bpf_ringbuf_output() helper in UAPI comments")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200727224715.652037-1-andriin@fb.com

Assign "lsm" as a printed name for BPF_PROG_TYPE_LSM in bpftool, so that
it can use it when listing programs loaded on the system or when probing
features.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200724090618.16378-3-quentin@isovalent.com

For probing program and map types, bpftool loops on type values and uses
the relevant type name in prog_type_name[] or map_type_name[]. To ensure
the name exists, we exit from the loop if we go over the size of the
array.

However, this is not enough in the case where the arrays have "holes" in
them, program or map types for which they have no name, but not at the
end of the list. This is currently the case for BPF_PROG_TYPE_LSM, not
known to bpftool and which name is a null string. When probing for
features, bpftool attempts to strlen() that name and segfaults.

Let's fix it by skipping probes for "unknown" program and map types,
with an informational message giving the numeral value in that case.

Fixes: 93a3545d ("tools/bpftool: Add name mappings for SK_LOOKUP prog and attach type")
Reported-by: Paul Chaignon <paul@cilium.io>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200724090618.16378-2-quentin@isovalent.com

Andrii Nakryiko says:

====================
Following cgroup and netns examples, implement bpf_link support for XDP.

The semantics is described in patch #2. Program and link attachments are
mutually exclusive, in the sense that neither link can replace attached
program nor program can replace attached link. Link can't replace attached
link as well, as is the case for any other bpf_link implementation.

Patch #1 refactors existing BPF program-based attachment API and centralizes
high-level query/attach decisions in generic kernel code, while drivers are
kept simple and are instructed with low-level decisions about attaching and
detaching specific bpf_prog. This also makes QUERY command unnecessary, and
patch #8 removes support for it from all kernel drivers. If that's a bad idea,
we can drop that patch altogether.

With refactoring in patch #1, adding bpf_xdp_link is completely transparent to
drivers, they are still functioning at the level of "effective" bpf_prog, that
should be called in XDP data path.

Corresponding libbpf support for BPF XDP link is added in patch #5.

v3->v4:
- fix a compilation warning in one of drivers (Jakub);

v2->v3:
- fix build when CONFIG_BPF_SYSCALL=n (kernel test robot);

v1->v2:
- fix prog refcounting bug (David);
- split dev_change_xdp_fd() changes into 2 patches (David);
- add extack messages to all user-induced errors (David).
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Now that BPF program/link management is centralized in generic net_device
code, kernel code never queries program id from drivers, so
XDP_QUERY_PROG/XDP_QUERY_PROG_HW commands are unnecessary.

This patch removes all the implementations of those commands in kernel, along
the xdp_attachment_query().

This patch was compile-tested on allyesconfig.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-10-andriin@fb.com

Add selftest validating all the attachment logic around BPF XDP link. Test
also link updates and get_obj_info() APIs.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-9-andriin@fb.com

Sync UAPI header and add support for using bpf_link-based XDP attachment.
Make xdp/ prog type set expected attach type. Kernel didn't enforce
attach_type for XDP programs before, so there is no backwards compatiblity
issues there.

Also fix section_names selftest to recognize that xdp prog types now have
expected attach type.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-8-andriin@fb.com

Implement XDP link-specific show_fdinfo and link_info to emit ifindex.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-7-andriin@fb.com

Add support for LINK_UPDATE command for BPF XDP link to enable reliable
replacement of underlying BPF program.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-6-andriin@fb.com

Add bpf_link-based API (bpf_xdp_link) to attach BPF XDP program through
BPF_LINK_CREATE command.

bpf_xdp_link is mutually exclusive with direct BPF program attachment,
previous BPF program should be detached prior to attempting to create a new
bpf_xdp_link attachment (for a given XDP mode). Once BPF link is attached, it
can't be replaced by other BPF program attachment or link attachment. It will
be detached only when the last BPF link FD is closed.

bpf_xdp_link will be auto-detached when net_device is shutdown, similarly to
how other BPF links behave (cgroup, flow_dissector). At that point bpf_link
will become defunct, but won't be destroyed until last FD is closed.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-5-andriin@fb.com

Further refactor XDP attachment code. dev_change_xdp_fd() is split into two
parts: getting bpf_progs from FDs and attachment logic, working with
bpf_progs. This makes attachment  logic a bit more straightforward and
prepares code for bpf_xdp_link inclusion, which will share the common logic.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-4-andriin@fb.com

Instead of delegating to drivers, maintain information about which BPF
programs are attached in which XDP modes (generic/skb, driver, or hardware)
locally in net_device. This effectively obsoletes XDP_QUERY_PROG command.

Such re-organization simplifies existing code already. But it also allows to
further add bpf_link-based XDP attachments without drivers having to know
about any of this at all, which seems like a good setup.
XDP_SETUP_PROG/XDP_SETUP_PROG_HW are just low-level commands to driver to
install/uninstall active BPF program. All the higher-level concerns about
prog/link interaction will be contained within generic driver-agnostic logic.

All the XDP_QUERY_PROG calls to driver in dev_xdp_uninstall() were removed.
It's not clear for me why dev_xdp_uninstall() were passing previous prog_flags
when resetting installed programs. That seems unnecessary, plus most drivers
don't populate prog_flags anyways. Having XDP_SETUP_PROG vs XDP_SETUP_PROG_HW
should be enough of an indicator of what is required of driver to correctly
reset active BPF program. dev_xdp_uninstall() is also generalized as an
iteration over all three supported mode.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-3-andriin@fb.com