Split BPF operations that are allowed under CAP_SYS_ADMIN into
combination of CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN.
For backward compatibility include them in CAP_SYS_ADMIN as well.

The end result provides simple safety model for applications that use BPF:
- to load tracing program types
  BPF_PROG_TYPE_{KPROBE, TRACEPOINT, PERF_EVENT, RAW_TRACEPOINT, etc}
  use CAP_BPF and CAP_PERFMON
- to load networking program types
  BPF_PROG_TYPE_{SCHED_CLS, XDP, SK_SKB, etc}
  use CAP_BPF and CAP_NET_ADMIN

There are few exceptions from this rule:
- bpf_trace_printk() is allowed in networking programs, but it's using
  tracing mechanism, hence this helper needs additional CAP_PERFMON
  if networking program is using this helper.
- BPF_F_ZERO_SEED flag for hash/lru map is allowed under CAP_SYS_ADMIN only
  to discourage production use.
- BPF HW offload is allowed under CAP_SYS_ADMIN.
- bpf_probe_write_user() is allowed under CAP_SYS_ADMIN only.

CAPs are not checked at attach/detach time with two exceptions:
- loading BPF_PROG_TYPE_CGROUP_SKB is allowed for unprivileged users,
  hence CAP_NET_ADMIN is required at attach time.
- flow_dissector detach doesn't check prog FD at detach,
  hence CAP_NET_ADMIN is required at detach time.

CAP_SYS_ADMIN is required to iterate BPF objects (progs, maps, links) via get_next_id
command and convert them to file descriptor via GET_FD_BY_ID command.
This restriction guarantees that mutliple tasks with CAP_BPF are not able to
affect each other. That leads to clean isolation of tasks. For example:
task A with CAP_BPF and CAP_NET_ADMIN loads and attaches a firewall via bpf_link.
task B with the same capabilities cannot detach that firewall unless
task A explicitly passed link FD to task B via scm_rights or bpffs.
CAP_SYS_ADMIN can still detach/unload everything.

Two networking user apps with CAP_SYS_ADMIN and CAP_NET_ADMIN can
accidentely mess with each other programs and maps.
Two networking user apps with CAP_NET_ADMIN and CAP_BPF cannot affect each other.

CAP_NET_ADMIN + CAP_BPF allows networking programs access only packet data.
Such networking progs cannot access arbitrary kernel memory or leak pointers.

bpftool, bpftrace, bcc tools binaries should NOT be installed with
CAP_BPF and CAP_PERFMON, since unpriv users will be able to read kernel secrets.
But users with these two permissions will be able to use these tracing tools.

CAP_PERFMON is least secure, since it allows kprobes and kernel memory access.
CAP_NET_ADMIN can stop network traffic via iproute2.
CAP_BPF is the safest from security point of view and harmless on its own.

Having CAP_BPF and/or CAP_NET_ADMIN is not enough to write into arbitrary map
and if that map is used by firewall-like bpf prog.
CAP_BPF allows many bpf prog_load commands in parallel. The verifier
may consume large amount of memory and significantly slow down the system.

Existing unprivileged BPF operations are not affected.
In particular unprivileged users are allowed to load socket_filter and cg_skb
program types and to create array, hash, prog_array, map-in-map map types.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200513230355.7858-2-alexei.starovoitov@gmail.com

In Cilium we've recently switched to make use of bpf_jiffies64() for
parts of our tc and XDP datapath since bpf_ktime_get_ns() is more
expensive and high-precision is not needed for our timeouts we have
anyway. Our agent has a probe manager which picks up the json of
bpftool's feature probe and we also use the macro output in our C
programs e.g. to have workarounds when helpers are not available on
older kernels.

Extend the kernel config info dump to also include the kernel's
CONFIG_HZ, and rework the probe_kernel_image_config() for allowing a
macro dump such that CONFIG_HZ can be propagated to BPF C code as a
simple define if available via config. Latter allows to have _compile-
time_ resolution of jiffies <-> sec conversion in our code since all
are propagated as known constants.

Given we cannot generally assume availability of kconfig everywhere,
we also have a kernel hz probe [0] as a fallback. Potentially, bpftool
could have an integrated probe fallback as well, although to derive it,
we might need to place it under 'bpftool feature probe full' or similar
given it would slow down the probing process overall. Yet 'full' doesn't
fit either for us since we don't want to pollute the kernel log with
warning messages from bpf_probe_write_user() and bpf_trace_printk() on
agent startup; I've left it out for the time being.

  [0] https://github.com/cilium/cilium/blob/master/bpf/cilium-probe-kernel-hz.cSigned-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NQuentin Monnet <quentin@isovalent.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200513075849.20868-1-daniel@iogearbox.net

Jesper Dangaard Brouer says:

====================
V4:
- Fixup checkpatch.pl issues
- Collected more ACKs

V3:
- Fix issue on virtio_net patch spotted by Jason Wang
- Adjust name for variable in mlx5 patch
- Collected more ACKs

V2:
- Fix bug in mlx5 for XDP_PASS case
- Collected nitpicks and ACKs from mailing list

V1:
- Fix bug in dpaa2

XDP have evolved to support several frame sizes, but xdp_buff was not
updated with this information. This have caused the side-effect that
XDP frame data hard end is unknown. This have limited the BPF-helper
bpf_xdp_adjust_tail to only shrink the packet. This patchset address
this and add packet tail extend/grow.

The purpose of the patchset is ALSO to reserve a memory area that can be
used for storing extra information, specifically for extending XDP with
multi-buffer support. One proposal is to use same layout as
skb_shared_info, which is why this area is currently 320 bytes.

When converting xdp_frame to SKB (veth and cpumap), the full tailroom
area can now be used and SKB truesize is now correct. For most
drivers this result in a much larger tailroom in SKB "head" data
area. The network stack can now take advantage of this when doing SKB
coalescing. Thus, a good driver test is to use xdp_redirect_cpu from
samples/bpf/ and do some TCP stream testing.

Use-cases for tail grow/extend:
(1) IPsec / XFRM needs a tail extend[1][2].
(2) DNS-cache responses in XDP.
(3) HAProxy ALOHA would need it to convert to XDP.
(4) Add tail info e.g. timestamp and collect via tcpdump

[1] http://vger.kernel.org/netconf2019_files/xfrm_xdp.pdf
[2] http://vger.kernel.org/netconf2019.html

Examples on howto access the tail area of an XDP packet is shown in the
XDP-tutorial example[3].

[3] https://github.com/xdp-project/xdp-tutorial/blob/master/experiment01-tailgrow/
====================
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Extend BPF selftest xdp_adjust_tail with grow tail tests, which is added
as subtest's. The first grow test stays in same form as original shrink
test. The second grow test use the newer bpf_prog_test_run_xattr() calls,
and does extra checking of data contents.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945350567.97035.9632611946765811876.stgit@firesoul

Current selftest for BPF-helper xdp_adjust_tail only shrink tail.
Make it more clear that this is a shrink test case.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945350058.97035.17280775016196207372.stgit@firesoul

Update the memory requirements, when adding xdp.frame_sz in BPF test_run
function bpf_prog_test_run_xdp() which e.g. is used by XDP selftests.

Specifically add the expected reserved tailroom, but also allocated a
larger memory area to reflect that XDP frames usually comes in this
format. Limit the provided packet data size to 4096 minus headroom +
tailroom, as this also reflect a common 3520 bytes MTU limit with XDP.

Note that bpf_test_init already use a memory allocation method that clears
memory.  Thus, this already guards against leaking uninit kernel memory.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945349549.97035.15316291762482444006.stgit@firesoul

Clearing memory of tail when grow happens, because it is too easy
to write a XDP_PASS program that extend the tail, which expose
this memory to users that can run tcpdump.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945349039.97035.5262100484553494.stgit@firesoul

Finally, after all drivers have a frame size, allow BPF-helper
bpf_xdp_adjust_tail() to grow or extend packet size at frame tail.

Remember that helper/macro xdp_data_hard_end have reserved some
tailroom.  Thus, this helper makes sure that the BPF-prog don't have
access to this tailroom area.

V2: Remove one chicken check and use WARN_ONCE for other
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945348530.97035.12577148209134239291.stgit@firesoul

The mlx5 driver have multiple memory models, which are also changed
according to whether a XDP bpf_prog is attached.

The 'rx_striding_rq' setting is adjusted via ethtool priv-flags e.g.:
 # ethtool --set-priv-flags mlx5p2 rx_striding_rq off

On the general case with 4K page_size and regular MTU packet, then
the frame_sz is 2048 and 4096 when XDP is enabled, in both modes.

The info on the given frame size is stored differently depending on the
RQ-mode and encoded in a union in struct mlx5e_rq union wqe/mpwqe.
In rx striding mode rq->mpwqe.log_stride_sz is either 11 or 12, which
corresponds to 2048 or 4096 (MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ).
In non-striding mode (MLX5_WQ_TYPE_CYCLIC) the frag_stride is stored
in rq->wqe.info.arr[0].frag_stride, for the first fragment, which is
what the XDP case cares about.

To reduce effect on fast-path, this patch determine the frame_sz at
setup time, to avoid determining the memory model runtime. Variable
is named frame0_sz to make it clear that this is only the frame
size of the first fragment.

This mlx5 driver does a DMA-sync on XDP_TX action, but grow is safe
as it have done a DMA-map on the entire PAGE_SIZE. The driver also
already does a XDP length check against sq->hw_mtu on the possible
XDP xmit paths mlx5e_xmit_xdp_frame() + mlx5e_xmit_xdp_frame_mpwqe().

V3+4: Change variable name first_frame_sz to frame0_sz

V2: Fix that frag_size need to be recalc before creating SKB.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NTariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Link: https://lore.kernel.org/bpf/158945348021.97035.12295039384250022883.stgit@firesoul

Intel drivers implement native AF_XDP zerocopy in separate C-files,
that have its own invocation of bpf_prog_run_xdp(). The setup of
xdp_buff is also handled in separately from normal code path.

This patch update XDP frame_sz for AF_XDP zerocopy drivers i40e, ice
and ixgbe, as the code changes needed are very similar.  Introduce a
helper function xsk_umem_xdp_frame_sz() for calculating frame size.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NBjörn Töpel <bjorn.topel@intel.com>
Cc: intel-wired-lan@lists.osuosl.org
Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/158945347511.97035.8536753731329475655.stgit@firesoul

This driver uses different memory models depending on PAGE_SIZE at
compile time. For PAGE_SIZE 4K it uses page splitting, meaning for
normal MTU frame size is 2048 bytes (and headroom 192 bytes). For
larger MTUs the driver still use page splitting, by allocating
order-1 pages (8192 bytes) for RX frames. For PAGE_SIZE larger than
4K, driver instead advance its rx_buffer->page_offset with the frame
size "truesize".

For XDP frame size calculations, this mean that in PAGE_SIZE larger
than 4K mode the frame_sz change on a per packet basis. For the page
split 4K PAGE_SIZE mode, xdp.frame_sz is more constant and can be
updated once outside the main NAPI loop.

The default setting in the driver uses build_skb(), which provides
the necessary headroom and tailroom for XDP-redirect in RX-frame
(in both modes).

There is one complication, which is legacy-rx mode (configurable via
ethtool priv-flags). There are zero headroom in this mode, which is a
requirement for XDP-redirect to work. The conversion to xdp_frame
(convert_to_xdp_frame) will detect this insufficient space, and
xdp_do_redirect() call will fail. This is deemed acceptable, as it
allows other XDP actions to still work in legacy-mode. In
legacy-mode + larger PAGE_SIZE due to lacking tailroom, we also
accept that xdp_adjust_tail shrink doesn't work.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Link: https://lore.kernel.org/bpf/158945347002.97035.328088795813704587.stgit@firesoul

This driver uses different memory models depending on PAGE_SIZE at
compile time. For PAGE_SIZE 4K it uses page splitting, meaning for
normal MTU frame size is 2048 bytes (and headroom 192 bytes). For
larger MTUs the driver still use page splitting, by allocating
order-1 pages (8192 bytes) for RX frames. For PAGE_SIZE larger than
4K, driver instead advance its rx_buffer->page_offset with the frame
size "truesize".

For XDP frame size calculations, this mean that in PAGE_SIZE larger
than 4K mode the frame_sz change on a per packet basis. For the page
split 4K PAGE_SIZE mode, xdp.frame_sz is more constant and can be
updated once outside the main NAPI loop.

The default setting in the driver uses build_skb(), which provides
the necessary headroom and tailroom for XDP-redirect in RX-frame
(in both modes).

There is one complication, which is legacy-rx mode (configurable via
ethtool priv-flags). There are zero headroom in this mode, which is a
requirement for XDP-redirect to work. The conversion to xdp_frame
(convert_to_xdp_frame) will detect this insufficient space, and
xdp_do_redirect() call will fail. This is deemed acceptable, as it
allows other XDP actions to still work in legacy-mode. In
legacy-mode + larger PAGE_SIZE due to lacking tailroom, we also
accept that xdp_adjust_tail shrink doesn't work.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Link: https://lore.kernel.org/bpf/158945346494.97035.12809400414566061815.stgit@firesoul

This patch mirrors the changes to ixgbe in previous patch.

This VF driver doesn't support XDP_REDIRECT, but correct tailroom is
still necessary for BPF-helper xdp_adjust_tail.  In legacy-mode +
larger PAGE_SIZE, due to lacking tailroom, we accept that
xdp_adjust_tail shrink doesn't work.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Link: https://lore.kernel.org/bpf/158945345984.97035.13518286183248025173.stgit@firesoul

This driver uses different memory models depending on PAGE_SIZE at
compile time. For PAGE_SIZE 4K it uses page splitting, meaning for
normal MTU frame size is 2048 bytes (and headroom 192 bytes). For
larger MTUs the driver still use page splitting, by allocating
order-1 pages (8192 bytes) for RX frames. For PAGE_SIZE larger than
4K, driver instead advance its rx_buffer->page_offset with the frame
size "truesize".

For XDP frame size calculations, this mean that in PAGE_SIZE larger
than 4K mode the frame_sz change on a per packet basis. For the page
split 4K PAGE_SIZE mode, xdp.frame_sz is more constant and can be
updated once outside the main NAPI loop.

The default setting in the driver uses build_skb(), which provides
the necessary headroom and tailroom for XDP-redirect in RX-frame
(in both modes).

There is one complication, which is legacy-rx mode (configurable via
ethtool priv-flags). There are zero headroom in this mode, which is a
requirement for XDP-redirect to work. The conversion to xdp_frame
(convert_to_xdp_frame) will detect this insufficient space, and
xdp_do_redirect() call will fail. This is deemed acceptable, as it
allows other XDP actions to still work in legacy-mode. In
legacy-mode + larger PAGE_SIZE due to lacking tailroom, we also
accept that xdp_adjust_tail shrink doesn't work.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: intel-wired-lan@lists.osuosl.org
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Link: https://lore.kernel.org/bpf/158945345455.97035.14334355929030628741.stgit@firesoul

The ixgbe driver have another memory model when compiled on archs with
PAGE_SIZE above 4096 bytes. In this mode it doesn't split the page in
two halves, but instead increment rx_buffer->page_offset by truesize of
packet (which include headroom and tailroom for skb_shared_info).

This is done correctly in ixgbe_build_skb(), but in ixgbe_rx_buffer_flip
which is currently only called on XDP_TX and XDP_REDIRECT, it forgets
to add the tailroom for skb_shared_info. This breaks XDP_REDIRECT, for
veth and cpumap.  Fix by adding size of skb_shared_info tailroom.

Maintainers notice: This fix have been queued to Jeff.

Fixes: 64530739 ("ixgbe: add initial support for xdp redirect")
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Link: https://lore.kernel.org/bpf/158945344946.97035.17031588499266605743.stgit@firesoul

The virtio_net driver is running inside the guest-OS. There are two
XDP receive code-paths in virtio_net, namely receive_small() and
receive_mergeable(). The receive_big() function does not support XDP.

In receive_small() the frame size is available in buflen. The buffer
backing these frames are allocated in add_recvbuf_small() with same
size, except for the headroom, but tailroom have reserved room for
skb_shared_info. The headroom is encoded in ctx pointer as a value.

In receive_mergeable() the frame size is more dynamic. There are two
basic cases: (1) buffer size is based on a exponentially weighted
moving average (see DECLARE_EWMA) of packet length. Or (2) in case
virtnet_get_headroom() have any headroom then buffer size is
PAGE_SIZE. The ctx pointer is this time used for encoding two values;
the buffer len "truesize" and headroom. In case (1) if the rx buffer
size is underestimated, the packet will have been split over more
buffers (num_buf info in virtio_net_hdr_mrg_rxbuf placed in top of
buffer area). If that happens the XDP path does a xdp_linearize_page
operation.

V3: Adjust frame_sz in receive_mergeable() case, spotted by Jason Wang.

The code is really hard to follow, so some hints to reviewers.
The receive_mergeable() case gets frames that were allocated in
add_recvbuf_mergeable() which uses headroom=virtnet_get_headroom(),
and 'buf' ptr is advanced this headroom.  The headroom can only
be 0 or VIRTIO_XDP_HEADROOM, as virtnet_get_headroom is really
simple:

  static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
  {
	return vi->xdp_queue_pairs ? VIRTIO_XDP_HEADROOM : 0;
  }

As frame_sz is an offset size from xdp.data_hard_start, reviewers
should notice how this is calculated in receive_mergeable():

  int offset = buf - page_address(page);
  [...]
  data = page_address(xdp_page) + offset;
  xdp.data_hard_start = data - VIRTIO_XDP_HEADROOM + vi->hdr_len;

The calculated offset will always be VIRTIO_XDP_HEADROOM when
reaching this code.  Thus, xdp.data_hard_start will be page-start
address plus vi->hdr_len.  Given this xdp.frame_sz need to be
reduced with vi->hdr_len size.

IMHO a followup patch should cleanup this code to make it easier
to maintain and understand, but it is outside the scope of this
patchset.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/bpf/158945344436.97035.9445115070189151680.stgit@firesoul

In vhost_net_build_xdp() the 'buf' that gets queued via an xdp_buff
have embedded a struct tun_xdp_hdr (located at xdp->data_hard_start)
which contains the buffer length 'buflen' (with tailroom for
skb_shared_info). Also storing this buflen in xdp->frame_sz, does not
obsolete struct tun_xdp_hdr, as it also contains a struct
virtio_net_hdr with other information.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/bpf/158945343928.97035.4620233649151726289.stgit@firesoul

The tun driver have two code paths for running XDP (bpf_prog_run_xdp).
In both cases 'buflen' contains enough tailroom for skb_shared_info.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/bpf/158945343419.97035.9594485183958037621.stgit@firesoul

The netronome nfp driver use PAGE_SIZE when xdp_prog is set, but
xdp.data_hard_start begins at offset NFP_NET_RX_BUF_HEADROOM.
Thus, adjust for this when setting xdp.frame_sz, as it counts
from data_hard_start.

When doing XDP_TX this driver is smart and instead of a full DMA-map
does a DMA-sync on with packet length. As xdp_adjust_tail can now
grow packet length, add checks to make sure that grow size is within
the DMA-mapped size.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NJakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/158945342911.97035.11214251236208648808.stgit@firesoul

To help reviewers these are the defines related to RCV_FRAG_LEN

 #define DMA_BUFFER_LEN	1536 /* In multiples of 128bytes */
 #define RCV_FRAG_LEN	(SKB_DATA_ALIGN(DMA_BUFFER_LEN + NET_SKB_PAD) + \
			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: Sunil Goutham <sgoutham@marvell.com>
Cc: Robert Richter <rrichter@marvell.com>
Link: https://lore.kernel.org/bpf/158945342402.97035.12649844447148990032.stgit@firesoul

The mlx4 drivers size of memory backing the RX packet is stored in
frag_stride. For XDP mode this will be PAGE_SIZE (normally 4096).
For normal mode frag_stride is 2048.

Also adjust MLX4_EN_MAX_XDP_MTU to take tailroom into account.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Link: https://lore.kernel.org/bpf/158945341893.97035.2688142527052329942.stgit@firesoul

Frame size ENA_PAGE_SIZE is limited to 16K on systems with larger
PAGE_SIZE than 16K. Change ENA_XDP_MAX_MTU to also take into account
the reserved tailroom.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NSameeh Jubran <sameehj@amazon.com>
Cc: Arthur Kiyanovski <akiyano@amazon.com>
Link: https://lore.kernel.org/bpf/158945341384.97035.907403694833419456.stgit@firesoul

The driver code cpsw.c and cpsw_new.c both use page_pool
with default order-0 pages or their RX-pages.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://lore.kernel.org/bpf/158945340875.97035.752144756428532878.stgit@firesoul

The driver qede uses a full page, when XDP is enabled. The drivers value
in rx_buf_seg_size (struct qede_rx_queue) will be PAGE_SIZE when an
XDP bpf_prog is attached.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: Ariel Elior <aelior@marvell.com>
Cc: GR-everest-linux-l2@marvell.com
Link: https://lore.kernel.org/bpf/158945340366.97035.7764939691580349618.stgit@firesoul

The hyperv NIC driver does memory allocation and copy even without XDP.
In XDP mode it will allocate a new page for each packet and copy over
the payload, before invoking the XDP BPF-prog.

The positive thing it that its easy to determine the xdp.frame_sz.

The XDP implementation for hv_netvsc transparently passes xdp_prog
to the associated VF NIC. Many of the Azure VMs are using SRIOV, so
majority of the data are actually processed directly on the VF driver's XDP
path. So the overhead of the synthetic data path (hv_netvsc) is minimal.

Then XDP is enabled on this driver, XDP_PASS and XDP_TX will create the
SKB via build_skb (based on the newly allocated page). Now using XDP
frame_sz this will provide more skb_tailroom, which netstack can use for
SKB coalescing (e.g tcp_try_coalesce -> skb_try_coalesce).

V3: Adjust patch desc to be more positive.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Link: https://lore.kernel.org/bpf/158945339857.97035.10212138582505736163.stgit@firesoul

The dpaa2-eth driver reserve some headroom used for hardware and
software annotation area in RX/TX buffers. Thus, xdp.data_hard_start
doesn't start at page boundary.

When XDP is configured the area reserved via dpaa2_fd_get_offset(fd) is
448 bytes of which XDP have reserved 256 bytes. As frame_sz is
calculated as an offset from xdp_buff.data_hard_start, an adjust from
the full PAGE_SIZE == DPAA2_ETH_RX_BUF_RAW_SIZE.

When doing XDP_REDIRECT, the driver doesn't need this reserved headroom
any-longer and allows xdp_do_redirect() to use it. This is an advantage
for the drivers own ndo-xdp_xmit, as it uses part of this headroom for
itself.  Patch also adjust frame_sz in this case.

The driver cannot support XDP data_meta, because it uses the headroom
just before xdp.data for struct dpaa2_eth_swa (DPAA2_ETH_SWA_SIZE=64),
when transmitting the packet. When transmitting a xdp_frame in
dpaa2_eth_xdp_xmit_frame (call via ndo_xdp_xmit) is uses this area to
store a pointer to xdp_frame and dma_size, which is used in TX
completion (free_tx_fd) to return frame via xdp_return_frame().
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Link: https://lore.kernel.org/bpf/158945339348.97035.8562488847066908856.stgit@firesoul

The veth driver can run XDP in "native" mode in it's own NAPI
handler, and since commit 9fc8d518 ("veth: Handle xdp_frames in
xdp napi ring") packets can come in two forms either xdp_frame or
skb, calling respectively veth_xdp_rcv_one() or veth_xdp_rcv_skb().

For packets to arrive in xdp_frame format, they will have been
redirected from an XDP native driver. In case of XDP_PASS or no
XDP-prog attached, the veth driver will allocate and create an SKB.

The current code in veth_xdp_rcv_one() xdp_frame case, had to guess
the frame truesize of the incoming xdp_frame, when using
veth_build_skb(). With xdp_frame->frame_sz this is not longer
necessary.

Calculating the frame_sz in veth_xdp_rcv_skb() skb case, is done
similar to the XDP-generic handling code in net/core/dev.c.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NLorenzo Bianconi <lorenzo@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Acked-by: NToshiaki Makita <toshiaki.makita1@gmail.com>
Link: https://lore.kernel.org/bpf/158945338840.97035.935897116345700902.stgit@firesoul

When native XDP redirect into a veth device, the frame arrives in the
xdp_frame structure. It is then processed in veth_xdp_rcv_one(),
which can run a new XDP bpf_prog on the packet. Doing so requires
converting xdp_frame to xdp_buff, but the tricky part is that
xdp_frame memory area is located in the top (data_hard_start) memory
area that xdp_buff will point into.

The current code tried to protect the xdp_frame area, by assigning
xdp_buff.data_hard_start past this memory. This results in 32 bytes
less headroom to expand into via BPF-helper bpf_xdp_adjust_head().

This protect step is actually not needed, because BPF-helper
bpf_xdp_adjust_head() already reserve this area, and don't allow
BPF-prog to expand into it. Thus, it is safe to point data_hard_start
directly at xdp_frame memory area.

Fixes: 9fc8d518 ("veth: Handle xdp_frames in xdp napi ring")
Reported-by: NMao Wenan <maowenan@huawei.com>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToshiaki Makita <toshiaki.makita1@gmail.com>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945338331.97035.5923525383710752178.stgit@firesoul

Knowing the memory size backing the packet/xdp_frame data area, and
knowing it already have reserved room for skb_shared_info, simplifies
using build_skb significantly.

With this change we no-longer lie about the SKB truesize, but more
importantly a significant larger skb_tailroom is now provided, e.g. when
drivers uses a full PAGE_SIZE. This extra tailroom (in linear area) can be
used by the network stack when coalescing SKBs (e.g. in skb_try_coalesce,
see TCP cases where tcp_queue_rcv() can 'eat' skb).
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945337822.97035.13557959180460986059.stgit@firesoul

Use hole in struct xdp_frame, when adding member frame_sz, which keeps
same sizeof struct (32 bytes)

Drivers ixgbe and sfc had bug cases where the necessary/expected
tailroom was not reserved. This can lead to some hard to catch memory
corruption issues. Having the drivers frame_sz this can be detected when
packet length/end via xdp->data_end exceed the xdp_data_hard_end
pointer, which accounts for the reserved the tailroom.

When detecting this driver issue, simply fail the conversion with NULL,
which results in feedback to driver (failing xdp_do_redirect()) causing
driver to drop packet. Given the lack of consistent XDP stats, this can
be hard to troubleshoot. And given this is a driver bug, we want to
generate some more noise in form of a WARN stack dump (to ID the driver
code that inlined convert_to_xdp_frame).

Inlining the WARN macro is problematic, because it adds an asm
instruction (on Intel CPUs ud2) what influence instruction cache
prefetching. Thus, introduce xdp_warn and macro XDP_WARN, to avoid this
and at the same time make identifying the function and line of this
inlined function easier.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945337313.97035.10015729316710496600.stgit@firesoul

The SKB "head" pointer points to the data area that contains
skb_shared_info, that can be found via skb_end_pointer(). Given
xdp->data_hard_start have been established (basically pointing to
skb->head), frame size is between skb_end_pointer() and data_hard_start,
plus the size reserved to skb_shared_info.

Change the bpf_xdp_adjust_tail offset adjust of skb->len, to be a positive
offset number on grow, and negative number on shrink.  As this seems more
natural when reading the code.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945336804.97035.7164852191163722056.stgit@firesoul

This driver takes advantage of page_pool PP_FLAG_DMA_SYNC_DEV that
can help reduce the number of cache-lines that need to be flushed
when doing DMA sync for_device. Due to xdp_adjust_tail can grow the
area accessible to the by the CPU (can possibly write into), then max
sync length *after* bpf_prog_run_xdp() needs to be taken into account.

For XDP_TX action the driver is smart and does DMA-sync. When growing
tail this is still safe, because page_pool have DMA-mapped the entire
page size.
Signed-off-by: NIlias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NLorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/bpf/158945336295.97035.15034759661036971024.stgit@firesoul

This marvell driver mvneta uses PAGE_SIZE frames, which makes it
really easy to convert.  Driver updates rxq and now frame_sz
once per NAPI call.

This driver takes advantage of page_pool PP_FLAG_DMA_SYNC_DEV that
can help reduce the number of cache-lines that need to be flushed
when doing DMA sync for_device. Due to xdp_adjust_tail can grow the
area accessible to the by the CPU (can possibly write into), then max
sync length *after* bpf_prog_run_xdp() needs to be taken into account.

For XDP_TX action the driver is smart and does DMA-sync. When growing
tail this is still safe, because page_pool have DMA-mapped the entire
page size.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NLorenzo Bianconi <lorenzo@kernel.org>
Cc: thomas.petazzoni@bootlin.com
Link: https://lore.kernel.org/bpf/158945335786.97035.12714388304493736747.stgit@firesoul

This driver uses RX page-split when possible. It was recently fixed
in commit 86e85bf6 ("sfc: fix XDP-redirect in this driver") to
add needed tailroom for XDP-redirect.

After the fix efx->rx_page_buf_step is the frame size, with enough
head and tail-room for XDP-redirect.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945335278.97035.14611425333184621652.stgit@firesoul

This driver uses full PAGE_SIZE pages when XDP is enabled.

In case of XDP uses driver uses __bnxt_alloc_rx_page which does full
page DMA-map. Thus, xdp_adjust_tail grow is DMA compliant for XDP_TX
action that does DMA-sync.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NAndy Gospodarek <gospo@broadcom.com>
Cc: Michael Chan <michael.chan@broadcom.com>
Cc: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Link: https://lore.kernel.org/bpf/158945334769.97035.13437970179897613984.stgit@firesoul

XDP have evolved to support several frame sizes, but xdp_buff was not
updated with this information. The frame size (frame_sz) member of
xdp_buff is introduced to know the real size of the memory the frame is
delivered in.

When introducing this also make it clear that some tailroom is
reserved/required when creating SKBs using build_skb().

It would also have been an option to introduce a pointer to
data_hard_end (with reserved offset). The advantage with frame_sz is
that (like rxq) drivers only need to setup/assign this value once per
NAPI cycle. Due to XDP-generic (and some drivers) it's not possible to
store frame_sz inside xdp_rxq_info, because it's varies per packet as it
can be based/depend on packet length.

V2: nitpick: deduct -> deduce
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158945334261.97035.555255657490688547.stgit@firesoul

Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-05-14

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Merged tag 'perf-for-bpf-2020-05-06' from tip tree that includes CAP_PERFMON.

2) support for narrow loads in bpf_sock_addr progs and additional
   helpers in cg-skb progs, from Andrey.

3) bpf benchmark runner, from Andrii.

4) arm and riscv JIT optimizations, from Luke.

5) bpf iterator infrastructure, from Yonghong.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Andrey Ignatov says:

====================
v2->v3:
- better documentation for bpf_sk_cgroup_id in uapi (Yonghong Song)
- save/restore errno in network helpers (Yonghong Song)
- cleanup leftover after switching selftest to skeleton (Yonghong Song)
- switch from map to skel->bss in selftest (Yonghong Song)

v1->v2:
- switch selftests to skeleton.

This patch set allows a bunch of existing sk lookup and skb cgroup id
helpers, and adds two new bpf_sk_{,ancestor_}cgroup_id helpers to be used
in cgroup skb programs.

It fills the gap to cover a use-case to apply intra-host cgroup-bpf network
policy based on a source cgroup a packet comes from.

For example, there can be multiple containers A, B, C running on a host.
Every such container runs in its own cgroup that can have multiple
sub-cgroups. But all these containers can share some IP addresses.

At the same time container A wants to have a policy for a server S running
in it so that only clients from this same container can connect to S, but
not from other containers (such as B, C). Source IP address can't be used
to decide whether to allow or deny a packet, but it looks reasonable to
filter by cgroup id.

The patch set allows to implement the following policy:
* when an ingress packet comes to container's cgroup, lookup peer (client)
  socket this packet comes from;
* having peer socket, get its cgroup id;
* compare peer cgroup id with self cgroup id and allow packet only if they
  match, i.e. it comes from same cgroup;
* the "sub-cgroup" part of the story can be addressed by getting not direct
  cgroup id of the peer socket, but ancestor cgroup id on specified level,
  similar to existing "ancestor" flavors of cgroup id helpers.

A newly introduced selftest implements such a policy in its basic form to
provide a better idea on the use-case.

Patch 1 allows existing sk lookup helpers in cgroup skb.
Patch 2 allows skb_ancestor_cgroup_id in cgrou skb.
Patch 3 introduces two new helpers to get cgroup id of socket.
Patch 4 extends network helpers to use them in the next patch.
Patch 5 adds selftest / example of use-case.
====================
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

Test bpf_sk_lookup_tcp, bpf_sk_release, bpf_sk_cgroup_id and
bpf_sk_ancestor_cgroup_id helpers from cgroup skb program.

The test creates a testing cgroup, starts a TCPv6 server inside the
cgroup and creates two client sockets: one inside testing cgroup and one
outside.

Then it attaches cgroup skb program to the cgroup that checks all TCP
segments coming to the server and allows only those coming from the
cgroup of the server. If a segment comes from a peer outside of the
cgroup, it'll be dropped.

Finally the test checks that client from inside testing cgroup can
successfully connect to the server, but client outside the cgroup fails
to connect by timeout.

The main goal of the test is to check newly introduced
bpf_sk_{,ancestor_}cgroup_id helpers.

It also checks a couple of socket lookup helpers (tcp & release), but
lookup helpers were introduced much earlier and covered by other tests.
Here it's mostly checked that they can be called from cgroup skb.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/171f4c5d75e8ff4fe1c4e8c1c12288b5240a4549.1589486450.git.rdna@fb.com

Add two new network helpers.

connect_fd_to_fd connects an already created client socket fd to address
of server fd. Sometimes it's useful to separate client socket creation
and connecting this socket to a server, e.g. if client socket has to be
created in a cgroup different from that of server cgroup.

Additionally connect_to_fd is now implemented using connect_fd_to_fd,
both helpers don't treat EINPROGRESS as an error and let caller decide
how to proceed with it.

connect_wait is a helper to work with non-blocking client sockets so
that if connect_to_fd or connect_fd_to_fd returned -1 with errno ==
EINPROGRESS, caller can wait for connect to finish or for connection
timeout. The helper returns -1 on error, 0 on timeout (1sec,
hard-coded), and positive number on success.
Signed-off-by: NAndrey Ignatov <rdna@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/1403fab72300f379ca97ead4820ae43eac4414ef.1589486450.git.rdna@fb.com