Commit Graph

33 Commits

Author SHA1 Message Date
Ido Schimmel
b3899830aa bpf: lwtunnel: Unmask upper DSCP bits in bpf_lwt_xmit_reroute()
Unmask the upper DSCP bits when calling ip_route_output_key() so that in
the future it could perform the FIB lookup according to the full DSCP
value.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-09-09 14:14:52 +01:00
Sebastian Andrzej Siewior
401cb7dae8 net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.
The XDP redirect process is two staged:
- bpf_prog_run_xdp() is invoked to run a eBPF program which inspects the
  packet and makes decisions. While doing that, the per-CPU variable
  bpf_redirect_info is used.

- Afterwards xdp_do_redirect() is invoked and accesses bpf_redirect_info
  and it may also access other per-CPU variables like xskmap_flush_list.

At the very end of the NAPI callback, xdp_do_flush() is invoked which
does not access bpf_redirect_info but will touch the individual per-CPU
lists.

The per-CPU variables are only used in the NAPI callback hence disabling
bottom halves is the only protection mechanism. Users from preemptible
context (like cpu_map_kthread_run()) explicitly disable bottom halves
for protections reasons.
Without locking in local_bh_disable() on PREEMPT_RT this data structure
requires explicit locking.

PREEMPT_RT has forced-threaded interrupts enabled and every
NAPI-callback runs in a thread. If each thread has its own data
structure then locking can be avoided.

Create a struct bpf_net_context which contains struct bpf_redirect_info.
Define the variable on stack, use bpf_net_ctx_set() to save a pointer to
it, bpf_net_ctx_clear() removes it again.
The bpf_net_ctx_set() may nest. For instance a function can be used from
within NET_RX_SOFTIRQ/ net_rx_action which uses bpf_net_ctx_set() and
NET_TX_SOFTIRQ which does not. Therefore only the first invocations
updates the pointer.
Use bpf_net_ctx_get_ri() as a wrapper to retrieve the current struct
bpf_redirect_info. The returned data structure is zero initialized to
ensure nothing is leaked from stack. This is done on first usage of the
struct. bpf_net_ctx_set() sets bpf_redirect_info::kern_flags to 0 to
note that initialisation is required. First invocation of
bpf_net_ctx_get_ri() will memset() the data structure and update
bpf_redirect_info::kern_flags.
bpf_redirect_info::nh is excluded from memset because it is only used
once BPF_F_NEIGH is set which also sets the nh member. The kern_flags is
moved past nh to exclude it from memset.

The pointer to bpf_net_context is saved task's task_struct. Using
always the bpf_net_context approach has the advantage that there is
almost zero differences between PREEMPT_RT and non-PREEMPT_RT builds.

Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-15-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-24 16:41:24 -07:00
Sebastian Andrzej Siewior
3414adbd6a lwt: Don't disable migration prio invoking BPF.
There is no need to explicitly disable migration if bottom halves are
also disabled. Disabling BH implies disabling migration.

Remove migrate_disable() and rely solely on disabling BH to remain on
the same CPU.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-12-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-24 16:41:23 -07:00
Yan Zhai
29b22badb7 lwt: Fix return values of BPF xmit ops
BPF encap ops can return different types of positive values, such like
NET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function
skb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return
values would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in
ip(6)_finish_output2. When this happens, skbs that have been freed would
continue to the neighbor subsystem, causing use-after-free bug and
kernel crashes.

To fix the incorrect behavior, skb_do_redirect return values can be
simply discarded, the same as tc-egress behavior. On the other hand,
bpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU
information. Thus convert its return values to avoid the conflict with
LWTUNNEL_XMIT_CONTINUE.

Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure")
Reported-by: Jordan Griege <jgriege@cloudflare.com>
Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/0d2b878186cfe215fec6b45769c1cd0591d3628d.1692326837.git.yan@cloudflare.com
2023-08-18 16:05:26 +02:00
Eyal Birger
b02d196c44 bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook
xmit_check_hhlen() observes the dst for getting the device hard header
length to make sure a modified packet can fit. When a helper which changes
the dst - such as bpf_skb_set_tunnel_key() - is called as part of the
xmit program the accessed dst is no longer valid.

This leads to the following splat:

 BUG: kernel NULL pointer dereference, address: 00000000000000de
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 0 PID: 798 Comm: ping Not tainted 5.18.0-rc2+ #103
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
 RIP: 0010:bpf_xmit+0xfb/0x17f
 Code: c6 c0 4d cd 8e 48 c7 c7 7d 33 f0 8e e8 42 09 fb ff 48 8b 45 58 48 8b 95 c8 00 00 00 48 2b 95 c0 00 00 00 48 83 e0 fe 48 8b 00 <0f> b7 80 de 00 00 00 39 c2 73 22 29 d0 b9 20 0a 00 00 31 d2 48 89
 RSP: 0018:ffffb148c0bc7b98 EFLAGS: 00010282
 RAX: 0000000000000000 RBX: 0000000000240008 RCX: 0000000000000000
 RDX: 0000000000000010 RSI: 00000000ffffffea RDI: 00000000ffffffff
 RBP: ffff922a828a4e00 R08: ffffffff8f1350e8 R09: 00000000ffffdfff
 R10: ffffffff8f055100 R11: ffffffff8f105100 R12: 0000000000000000
 R13: ffff922a828a4e00 R14: 0000000000000040 R15: 0000000000000000
 FS:  00007f414e8f0080(0000) GS:ffff922afdc00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000000000de CR3: 0000000002d80006 CR4: 0000000000370ef0
 Call Trace:
  <TASK>
  lwtunnel_xmit.cold+0x71/0xc8
  ip_finish_output2+0x279/0x520
  ? __ip_finish_output.part.0+0x21/0x130

Fix by fetching the device hard header length before running the BPF code.

Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220420165219.1755407-1-eyal.birger@gmail.com
2022-04-22 17:45:25 +02:00
Jakub Kicinski
b6459415b3 net: Don't include filter.h from net/sock.h
sock.h is pretty heavily used (5k objects rebuilt on x86 after
it's touched). We can drop the include of filter.h from it and
add a forward declaration of struct sk_filter instead.
This decreases the number of rebuilt objects when bpf.h
is touched from ~5k to ~1k.

There's a lot of missing includes this was masking. Primarily
in networking tho, this time.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org
2021-12-29 08:48:14 -08:00
Cong Wang
e3366884b3 lwt_bpf: Replace preempt_disable() with migrate_disable()
migrate_disable() is just a wrapper for preempt_disable() in
non-RT kernel. It is safe to replace it, and RT kernel will
benefit.

Note that it is introduced since Feb 2020.

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201205075946.497763-2-xiyou.wangcong@gmail.com
2020-12-07 11:53:40 -08:00
Dongdong Wang
d9054a1ff5 lwt: Disable BH too in run_lwt_bpf()
The per-cpu bpf_redirect_info is shared among all skb_do_redirect()
and BPF redirect helpers. Callers on RX path are all in BH context,
disabling preemption is not sufficient to prevent BH interruption.

In production, we observed strange packet drops because of the race
condition between LWT xmit and TC ingress, and we verified this issue
is fixed after we disable BH.

Although this bug was technically introduced from the beginning, that
is commit 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure"),
at that time call_rcu() had to be call_rcu_bh() to match the RCU context.
So this patch may not work well before RCU flavor consolidation has been
completed around v5.0.

Update the comments above the code too, as call_rcu() is now BH friendly.

Signed-off-by: Dongdong Wang <wangdongdong.6@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Cong Wang <cong.wang@bytedance.com>
Link: https://lore.kernel.org/bpf/20201205075946.497763-1-xiyou.wangcong@gmail.com
2020-12-07 11:53:39 -08:00
Alexander Aring
faee676944 net: add net available in build_state
The build_state callback of lwtunnel doesn't contain the net namespace
structure yet. This patch will add it so we can check on specific
address configuration at creation time of rpl source routes.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-29 22:30:57 -07:00
Sabrina Dubroca
6c8991f415 net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup
ipv6_stub uses the ip6_dst_lookup function to allow other modules to
perform IPv6 lookups. However, this function skips the XFRM layer
entirely.

All users of ipv6_stub->ip6_dst_lookup use ip_route_output_flow (via the
ip_route_output_key and ip_route_output helpers) for their IPv4 lookups,
which calls xfrm_lookup_route(). This patch fixes this inconsistent
behavior by switching the stub to ip6_dst_lookup_flow, which also calls
xfrm_lookup_route().

This requires some changes in all the callers, as these two functions
take different arguments and have different return types.

Fixes: 5f81bd2e5d ("ipv6: export a stub for IPv6 symbols used by vxlan")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-04 12:27:13 -08:00
Jiri Benc
9e8acd9c44 bpf: lwtunnel: Fix reroute supplying invalid dst
The dst in bpf_input() has lwtstate field set. As it is of the
LWTUNNEL_ENCAP_BPF type, lwtstate->data is struct bpf_lwt. When the bpf
program returns BPF_LWT_REROUTE, ip_route_input_noref is directly called on
this skb. This causes invalid memory access, as ip_route_input_slow calls
skb_tunnel_info(skb) that expects the dst->lwstate->data to be
struct ip_tunnel_info. This results to struct bpf_lwt being accessed as
struct ip_tunnel_info.

Drop the dst before calling the IP route input functions (both for IPv4 and
IPv6).

Reported by KASAN.

Fixes: 3bd0b15281 ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Oskolkov <posk@google.com>
Link: https://lore.kernel.org/bpf/111664d58fe4e9dd9c8014bb3d0b2dab93086a9e.1570609794.git.jbenc@redhat.com
2019-10-14 11:43:48 -07:00
Thomas Gleixner
5b497af42f treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of version 2 of the gnu general public license as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 64 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:38 +02:00
Johannes Berg
8cb081746c netlink: make validation more configurable for future strictness
We currently have two levels of strict validation:

 1) liberal (default)
     - undefined (type >= max) & NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted
     - garbage at end of message accepted
 2) strict (opt-in)
     - NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted

Split out parsing strictness into four different options:
 * TRAILING     - check that there's no trailing data after parsing
                  attributes (in message or nested)
 * MAXTYPE      - reject attrs > max known type
 * UNSPEC       - reject attributes with NLA_UNSPEC policy entries
 * STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
 * nla_parse           -> nla_parse_deprecated
 * nla_parse_strict    -> nla_parse_deprecated_strict
 * nlmsg_parse         -> nlmsg_parse_deprecated
 * nlmsg_parse_strict  -> nlmsg_parse_deprecated_strict
 * nla_parse_nested    -> nla_parse_nested_deprecated
 * nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
    @@
    expression TB, MAX, HEAD, LEN, POL, EXT;
    @@
    -nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
    +nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression TB, MAX, NLA, POL, EXT;
    @@
    -nla_parse_nested(TB, MAX, NLA, POL, EXT)
    +nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

    @@
    expression START, MAX, POL, EXT;
    @@
    -nla_validate_nested(START, MAX, POL, EXT)
    +nla_validate_nested_deprecated(START, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, MAX, POL, EXT;
    @@
    -nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
    +nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-27 17:07:21 -04:00
Michal Kubecek
ae0be8de9a netlink: make nla_nest_start() add NLA_F_NESTED flag
Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-27 17:03:44 -04:00
David Ahern
3616d08bcb ipv6: Move ipv6 stubs to a separate header file
The number of stubs is growing and has nothing to do with addrconf.
Move the definition of the stubs to a separate header file and update
users. In the move, drop the vxlan specific comment before ipv6_stub.

Code move only; no functional change intended.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-29 10:53:45 -07:00
Peter Oskolkov
ea0371f787 net: fix GSO in bpf_lwt_push_ip_encap
GSO needs inner headers and inner protocol set properly to work.

skb->inner_mac_header: skb_reset_inner_headers() assigns the current
mac header value to inner_mac_header; but it is not set at the point,
so we need to call skb_reset_inner_mac_header, otherwise gre_gso_segment
fails: it does

    int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
    ...
    if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
    ...

skb->inner_protocol should also be correctly set.

Fixes: ca78801a81 ("bpf: handle GSO in bpf_lwt_push_encap")
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-03-07 10:41:29 +01:00
Peter Oskolkov
bd16693f35 net: fix double-free in bpf_lwt_xmit_reroute
dst_output() frees skb when it fails (see, for example,
ip_finish_output2), so it must not be freed in this case.

Fixes: 3bd0b15281 ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-02-24 22:24:50 -08:00
Peter Oskolkov
fb405883c1 bpf: fix memory leak in bpf_lwt_xmit_reroute
On error the skb should be freed. Tested with diff/steps
provided by David Ahern.

v2: surface routing errors to the user instead of a generic EINVAL,
    as suggested by David Ahern.

Reported-by: David Ahern <dsahern@gmail.com>
Fixes: 3bd0b15281 ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c")
Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-02-14 15:10:06 -08:00
Peter Oskolkov
3bd0b15281 bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c
This patch builds on top of the previous patch in the patchset,
which added BPF_LWT_ENCAP_IP mode to bpf_lwt_push_encap. As the
encapping can result in the skb needing to go via a different
interface/route/dst, bpf programs can indicate this by returning
BPF_LWT_REROUTE, which triggers a new route lookup for the skb.

v8 changes: fix kbuild errors when LWTUNNEL_BPF is builtin, but
   IPV6 is a module: as LWTUNNEL_BPF can only be either Y or N,
   call IPV6 routing functions only if they are built-in.

v9 changes:
   - fixed a kbuild test robot compiler warning;
   - call IPV6 routing functions via ipv6_stub.

v10 changes: removed unnecessary IS_ENABLED and pr_warn_once.

v11 changes: fixed a potential dst leak.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-02-13 18:27:55 -08:00
Peter Oskolkov
ca78801a81 bpf: handle GSO in bpf_lwt_push_encap
This patch adds handling of GSO packets in bpf_lwt_push_ip_encap()
(called from bpf_lwt_push_encap):

* IPIP, GRE, and UDP encapsulation types are deduced by looking
  into iphdr->protocol or ipv6hdr->next_header;
* SCTP GSO packets are not supported (as bpf_skb_proto_4_to_6
  and similar do);
* UDP_L4 GSO packets are also not supported (although they are
  not blocked in bpf_skb_proto_4_to_6 and similar), as
  skb_decrease_gso_size() will break it;
* SKB_GSO_DODGY bit is set.

Note: it may be possible to support SCTP and UDP_L4 gso packets;
      but as these cases seem to be not well handled by other
      tunneling/encapping code paths, the solution should
      be generic enough to apply to all tunneling/encapping code.

v8 changes:
   - make sure that if GRE or UDP encap is detected, there is
     enough of pushed bytes to cover both IP[v6] + GRE|UDP headers;
   - do not reject double-encapped packets;
   - whitelist TCP GSO packets rather than block SCTP GSO and
     UDP GSO.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-02-13 18:27:55 -08:00
Peter Oskolkov
52f278774e bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap
Implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap BPF helper.
It enables BPF programs (specifically, BPF_PROG_TYPE_LWT_IN and
BPF_PROG_TYPE_LWT_XMIT prog types) to add IP encapsulation headers
to packets (e.g. IP/GRE, GUE, IPIP).

This is useful when thousands of different short-lived flows should be
encapped, each with different and dynamically determined destination.
Although lwtunnels can be used in some of these scenarios, the ability
to dynamically generate encap headers adds more flexibility, e.g.
when routing depends on the state of the host (reflected in global bpf
maps).

v7 changes:
 - added a call skb_clear_hash();
 - removed calls to skb_set_transport_header();
 - refuse to encap GSO-enabled packets.

v8 changes:
 - fix build errors when LWT is not enabled.

Note: the next patch in the patchset with deal with GSO-enabled packets,
which are currently rejected at encapping attempt.

Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-02-13 18:27:55 -08:00
Willem de Bruijn
e7c87bd6cc bpf: in __bpf_redirect_no_mac pull mac only if present
Syzkaller was able to construct a packet of negative length by
redirecting from bpf_prog_test_run_skb with BPF_PROG_TYPE_LWT_XMIT:

    BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:345 [inline]
    BUG: KASAN: slab-out-of-bounds in skb_copy_from_linear_data include/linux/skbuff.h:3421 [inline]
    BUG: KASAN: slab-out-of-bounds in __pskb_copy_fclone+0x2dd/0xeb0 net/core/skbuff.c:1395
    Read of size 4294967282 at addr ffff8801d798009c by task syz-executor2/12942

    kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
    check_memory_region_inline mm/kasan/kasan.c:260 [inline]
    check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
    memcpy+0x23/0x50 mm/kasan/kasan.c:302
    memcpy include/linux/string.h:345 [inline]
    skb_copy_from_linear_data include/linux/skbuff.h:3421 [inline]
    __pskb_copy_fclone+0x2dd/0xeb0 net/core/skbuff.c:1395
    __pskb_copy include/linux/skbuff.h:1053 [inline]
    pskb_copy include/linux/skbuff.h:2904 [inline]
    skb_realloc_headroom+0xe7/0x120 net/core/skbuff.c:1539
    ipip6_tunnel_xmit net/ipv6/sit.c:965 [inline]
    sit_tunnel_xmit+0xe1b/0x30d0 net/ipv6/sit.c:1029
    __netdev_start_xmit include/linux/netdevice.h:4325 [inline]
    netdev_start_xmit include/linux/netdevice.h:4334 [inline]
    xmit_one net/core/dev.c:3219 [inline]
    dev_hard_start_xmit+0x295/0xc90 net/core/dev.c:3235
    __dev_queue_xmit+0x2f0d/0x3950 net/core/dev.c:3805
    dev_queue_xmit+0x17/0x20 net/core/dev.c:3838
    __bpf_tx_skb net/core/filter.c:2016 [inline]
    __bpf_redirect_common net/core/filter.c:2054 [inline]
    __bpf_redirect+0x5cf/0xb20 net/core/filter.c:2061
    ____bpf_clone_redirect net/core/filter.c:2094 [inline]
    bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2066
    bpf_prog_41f2bcae09cd4ac3+0xb25/0x1000

The generated test constructs a packet with mac header, network
header, skb->data pointing to network header and skb->len 0.

Redirecting to a sit0 through __bpf_redirect_no_mac pulls the
mac length, even though skb->data already is at skb->network_header.
bpf_prog_test_run_skb has already pulled it as LWT_XMIT !is_l2.

Update the offset calculation to pull only if skb->data differs
from skb->network_header, which is not true in this case.

The test itself can be run only from commit 1cf1cae963 ("bpf:
introduce BPF_PROG_TEST_RUN command"), but the same type of packets
with skb at network header could already be built from lwt xmit hooks,
so this fix is more relevant to that commit.

Also set the mac header on redirect from LWT_XMIT, as even after this
change to __bpf_redirect_no_mac that field is expected to be set, but
is not yet in ip_finish_output2.

Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-01-20 01:11:48 +01:00
David S. Miller
1ba982806c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:

====================
pull-request: bpf-next 2018-08-07

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

The main changes are:

1) Add cgroup local storage for BPF programs, which provides a fast
   accessible memory for storing various per-cgroup data like number
   of transmitted packets, etc, from Roman.

2) Support bpf_get_socket_cookie() BPF helper in several more program
   types that have a full socket available, from Andrey.

3) Significantly improve the performance of perf events which are
   reported from BPF offload. Also convert a couple of BPF AF_XDP
   samples overto use libbpf, both from Jakub.

4) seg6local LWT provides the End.DT6 action, which allows to
   decapsulate an outer IPv6 header containing a Segment Routing Header.
   Adds this action now to the seg6local BPF interface, from Mathieu.

5) Do not mark dst register as unbounded in MOV64 instruction when
   both src and dst register are the same, from Arthur.

6) Define u_smp_rmb() and u_smp_wmb() to their respective barrier
   instructions on arm64 for the AF_XDP sample code, from Brian.

7) Convert the tcp_client.py and tcp_server.py BPF selftest scripts
   over from Python 2 to Python 3, from Jeremy.

8) Enable BTF build flags to the BPF sample code Makefile, from Taeung.

9) Remove an unnecessary rcu_read_lock() in run_lwt_bpf(), from Taehee.

10) Several improvements to the README.rst from the BPF documentation
    to make it more consistent with RST format, from Tobin.

11) Replace all occurrences of strerror() by calls to strerror_r()
    in libbpf and fix a FORTIFY_SOURCE build error along with it,
    from Thomas.

12) Fix a bug in bpftool's get_btf() function to correctly propagate
    an error via PTR_ERR(), from Yue.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-07 11:02:05 -07:00
Taehee Yoo
1f821611f4 lwt_bpf: remove unnecessary rcu_read_lock in run_lwt_bpf
run_lwt_bpf is called by bpf_{input/output/xmit}.
These functions are already protected by rcu_read_lock.
because lwtunnel_{input/output/xmit} holds rcu_read_lock
and then calls bpf_{input/output/xmit}.
So that rcu_read_lock in the run_lwt_bpf is unnecessary.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-31 09:26:34 +02:00
Taehee Yoo
71eb5255f5 bpf: use GFP_ATOMIC instead of GFP_KERNEL in bpf_parse_prog()
bpf_parse_prog() is protected by rcu_read_lock().
so that GFP_KERNEL is not allowed in the bpf_parse_prog().

[51015.579396] =============================
[51015.579418] WARNING: suspicious RCU usage
[51015.579444] 4.18.0-rc6+ #208 Not tainted
[51015.579464] -----------------------------
[51015.579488] ./include/linux/rcupdate.h:303 Illegal context switch in RCU read-side critical section!
[51015.579510] other info that might help us debug this:
[51015.579532] rcu_scheduler_active = 2, debug_locks = 1
[51015.579556] 2 locks held by ip/1861:
[51015.579577]  #0: 00000000a8c12fd1 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x2e0/0x910
[51015.579711]  #1: 00000000bf815f8e (rcu_read_lock){....}, at: lwtunnel_build_state+0x96/0x390
[51015.579842] stack backtrace:
[51015.579869] CPU: 0 PID: 1861 Comm: ip Not tainted 4.18.0-rc6+ #208
[51015.579891] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
[51015.579911] Call Trace:
[51015.579950]  dump_stack+0x74/0xbb
[51015.580000]  ___might_sleep+0x16b/0x3a0
[51015.580047]  __kmalloc_track_caller+0x220/0x380
[51015.580077]  kmemdup+0x1c/0x40
[51015.580077]  bpf_parse_prog+0x10e/0x230
[51015.580164]  ? kasan_kmalloc+0xa0/0xd0
[51015.580164]  ? bpf_destroy_state+0x30/0x30
[51015.580164]  ? bpf_build_state+0xe2/0x3e0
[51015.580164]  bpf_build_state+0x1bb/0x3e0
[51015.580164]  ? bpf_parse_prog+0x230/0x230
[51015.580164]  ? lock_is_held_type+0x123/0x1a0
[51015.580164]  lwtunnel_build_state+0x1aa/0x390
[51015.580164]  fib_create_info+0x1579/0x33d0
[51015.580164]  ? sched_clock_local+0xe2/0x150
[51015.580164]  ? fib_info_update_nh_saddr+0x1f0/0x1f0
[51015.580164]  ? sched_clock_local+0xe2/0x150
[51015.580164]  fib_table_insert+0x201/0x1990
[51015.580164]  ? lock_downgrade+0x610/0x610
[51015.580164]  ? fib_table_lookup+0x1920/0x1920
[51015.580164]  ? lwtunnel_valid_encap_type.part.6+0xcb/0x3a0
[51015.580164]  ? rtm_to_fib_config+0x637/0xbd0
[51015.580164]  inet_rtm_newroute+0xed/0x1b0
[51015.580164]  ? rtm_to_fib_config+0xbd0/0xbd0
[51015.580164]  rtnetlink_rcv_msg+0x331/0x910
[ ... ]

Fixes: 3a0af8fd61 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-07-28 21:23:24 +02:00
Daniel Borkmann
6aaae2b6c4 bpf: rename bpf_compute_data_end into bpf_compute_data_pointers
Just do the rename into bpf_compute_data_pointers() as we'll add
one more pointer here to recompute.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-09-26 13:36:44 -07:00
David Ahern
9ae2872748 net: add extack arg to lwtunnel build state
Pass extack arg down to lwtunnel_build_state and the build_state callbacks.
Add messages for failures in lwtunnel_build_state, and add the extarg to
nla_parse where possible in the build_state callbacks.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-30 11:55:32 -04:00
Johannes Berg
fceb6435e8 netlink: pass extended ACK struct to parsing functions
Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-13 13:58:22 -04:00
David Ahern
30357d7d8a lwtunnel: remove device arg to lwtunnel_build_state
Nothing about lwt state requires a device reference, so remove the
input argument.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-30 15:14:22 -05:00
David S. Miller
4e8f2fc1a5 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Two trivial overlapping changes conflicts in MPLS and mlx5.

Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-28 10:33:06 -05:00
Robert Shearman
88ff7334f2 net: Specify the owning module for lwtunnel ops
Modules implementing lwtunnel ops should not be allowed to unload
while there is state alive using those ops, so specify the owning
module for all lwtunnel ops.

Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-24 16:21:36 -05:00
Wei Yongjun
79471b10d6 lwt_bpf: bpf_lwt_prog_cmp() can be static
Fixes the following sparse warning:

net/core/lwt_bpf.c:355:5: warning:
 symbol 'bpf_lwt_prog_cmp' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-12 10:04:40 -05:00
Thomas Graf
3a0af8fd61 bpf: BPF for lightweight tunnel infrastructure
Registers new BPF program types which correspond to the LWT hooks:
  - BPF_PROG_TYPE_LWT_IN   => dst_input()
  - BPF_PROG_TYPE_LWT_OUT  => dst_output()
  - BPF_PROG_TYPE_LWT_XMIT => lwtunnel_xmit()

The separate program types are required to differentiate between the
capabilities each LWT hook allows:

 * Programs attached to dst_input() or dst_output() are restricted and
   may only read the data of an skb. This prevent modification and
   possible invalidation of already validated packet headers on receive
   and the construction of illegal headers while the IP headers are
   still being assembled.

 * Programs attached to lwtunnel_xmit() are allowed to modify packet
   content as well as prepending an L2 header via a newly introduced
   helper bpf_skb_change_head(). This is safe as lwtunnel_xmit() is
   invoked after the IP header has been assembled completely.

All BPF programs receive an skb with L3 headers attached and may return
one of the following error codes:

 BPF_OK - Continue routing as per nexthop
 BPF_DROP - Drop skb and return EPERM
 BPF_REDIRECT - Redirect skb to device as per redirect() helper.
                (Only valid in lwtunnel_xmit() context)

The return codes are binary compatible with their TC_ACT_
relatives to ease compatibility.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-02 10:51:49 -05:00