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  1. Aug 27, 2020
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  5. Aug 25, 2020
    • Yonghong Song's avatar
      selftests/bpf: Enable tc verbose mode for test_sk_assign · 0fcdfffe
      Yonghong Song authored 
      

Currently test_sk_assign failed verifier with llvm11/llvm12.
During debugging, I found the default verifier output is
truncated like below
  Verifier analysis:

  Skipped 2200 bytes, use 'verb' option for the full verbose log.
  [...]
  off=23,r=34,imm=0) R5=inv0 R6=ctx(id=0,off=0,imm=0) R7=pkt(id=0,off=0,r=34,imm=0) R10=fp0
  80: (0f) r7 += r2
  last_idx 80 first_idx 21
  regs=4 stack=0 before 78: (16) if w3 == 0x11 goto pc+1
when I am using "./test_progs -vv -t assign".

The reason is tc verbose mode is not enabled.

This patched enabled tc verbose mode and the output looks like below
  Verifier analysis:

  0: (bf) r6 = r1
  1: (b4) w0 = 2
  2: (61) r1 = *(u32 *)(r6 +80)
  3: (61) r7 = *(u32 *)(r6 +76)
  4: (bf) r2 = r7
  5: (07) r2 += 14
  6: (2d) if r2 > r1 goto pc+61
   R0_w=inv2 R1_w=pkt_end(id=0,off=0,imm=0) R2_w=pkt(id=0,off=14,r=14,imm=0)
  ...

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200824222807.100200-1-yhs@fb.com
      0fcdfffe
    • Daniel T. Lee's avatar
      samples: bpf: Refactor tracepoint tracing programs with libbpf · f0c328f8
      Daniel T. Lee authored 
      

For the problem of increasing fragmentation of the bpf loader programs,
instead of using bpf_loader.o, which is used in samples/bpf, this
commit refactors the existing tracepoint tracing programs with libbbpf
bpf loader.

    - Adding a tracepoint event and attaching a bpf program to it was done
    through bpf_program_attach().
    - Instead of using the existing BPF MAP definition, MAP definition
    has been refactored with the new BTF-defined MAP format.

Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-4-danieltimlee@gmail.com
      f0c328f8
    • Daniel T. Lee's avatar
      samples: bpf: Refactor kprobe tracing programs with libbpf · 3677d0a1
      Daniel T. Lee authored 
      

For the problem of increasing fragmentation of the bpf loader programs,
instead of using bpf_loader.o, which is used in samples/bpf, this
commit refactors the existing kprobe tracing programs with libbbpf
bpf loader.

    - For kprobe events pointing to system calls, the SYSCALL() macro in
    trace_common.h was used.
    - Adding a kprobe event and attaching a bpf program to it was done
    through bpf_program_attach().
    - Instead of using the existing BPF MAP definition, MAP definition
    has been refactored with the new BTF-defined MAP format.

Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-3-danieltimlee@gmail.com
      3677d0a1
    • Daniel T. Lee's avatar
      samples: bpf: Cleanup bpf_load.o from Makefile · 35a8b6dd
      Daniel T. Lee authored 
      

Since commit cc7f641d ("samples: bpf: Refactor BPF map performance
test with libbpf") has ommited the removal of bpf_load.o from Makefile,
this commit removes the bpf_load.o rule for targets where bpf_load.o is
not used.

Fixes: cc7f641d ("samples: bpf: Refactor BPF map performance test with libbpf")
Signed-off-by: default avatarDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200823085334.9413-2-danieltimlee@gmail.com
      35a8b6dd
    • Lorenz Bauer's avatar
      selftests: bpf: Fix sockmap update nits · 8c3b3d97
      Lorenz Bauer authored 
      

Address review by Yonghong, to bring the new tests in line with the
usual code style.

Signed-off-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200824084523.13104-1-lmb@cloudflare.com
      8c3b3d97
    • Andrii Nakryiko's avatar
      libbpf: Fix type compatibility check copy-paste error · f872e4bc
      Andrii Nakryiko authored 
      

Fix copy-paste error in types compatibility check. Local type is accidentally
used instead of target type for the very first type check strictness check.
This can result in potentially less strict candidate comparison. Fix the
error.

Fixes: 3fc32f40 ("libbpf: Implement type-based CO-RE relocations support")
Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821225653.2180782-1-andriin@fb.com
      f872e4bc
    • Andrii Nakryiko's avatar
      libbpf: Avoid false unuinitialized variable warning in bpf_core_apply_relo · 3418c56d
      Andrii Nakryiko authored 
      

Some versions of GCC report uninitialized targ_spec usage. GCC is wrong, but
let's avoid unnecessary warnings.

Fixes: ddc7c304 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821225556.2178419-1-andriin@fb.com
      3418c56d
    • Jakub Sitnicki's avatar
      bpf: sk_lookup: Add user documentation · 07ff4f01
      Jakub Sitnicki authored 
      

Describe the purpose of BPF sk_lookup program, how it can be attached, when
it gets invoked, and what information gets passed to it. Point the reader
to examples and further documentation.

Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200821100226.403844-1-jakub@cloudflare.com
      07ff4f01
    • Jianlin Lv's avatar
      docs: Correct subject prefix and update LLVM info · 4d0d1673
      Jianlin Lv authored 
      

bpf_devel_QA.rst:152 The subject prefix information is not accurate, it
should be 'PATCH bpf-next v2'

Also update LLVM version info and add information about
‘-DLLVM_TARGETS_TO_BUILD’ to prompt the developer to build the desired
target.

Signed-off-by: default avatarJianlin Lv <Jianlin.Lv@arm.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200821052817.46887-1-Jianlin.Lv@arm.com
      4d0d1673
    • Alexei Starovoitov's avatar
      Merge branch 'bpf-tcp-header-opts' · 890f4365
      Alexei Starovoitov authored 
      

Martin KaFai Lau says:

====================
The earlier effort in BPF-TCP-CC allows the TCP Congestion Control
algorithm to be written in BPF.  It opens up opportunities to allow
a faster turnaround time in testing/releasing new congestion control
ideas to production environment.

The same flexibility can be extended to writing TCP header option.
It is not uncommon that people want to test new TCP header option
to improve the TCP performance.  Another use case is for data-center
that has a more controlled environment and has more flexibility in
putting header options for internal traffic only.

This patch set introduces the necessary BPF logic and API to
allow bpf program to write and parse header options.

There are also some changes to TCP and they are mostly to provide
the needed sk and skb info to the bpf program to make decision.

Patch 9 is the main patch and has more details on the API and design.

The set includes an example which sends the max delay ack in
the BPF TCP header option and the receiving side can
then adjust its RTO accordingly.

v5:
- Move some of the comments from git commit message to the UAPI bpf.h
  in patch 9

- Some variable clean up in the tests (patch 11).

v4:
- Since bpf-next is currently closed, tag the set with RFC to keep the
  review cadence

- Separate tcp changes in its own patches (5, 6, 7).  It is a bit
  tricky since most of the tcp changes is to call out the bpf prog to
  write and parse the header.  The write and parse callout has been
  modularized into a few bpf_skops_* function in v3.

  This revision (v4) tries to move those bpf_skops_* functions into separate
  TCP patches.  However, they will be half implemented to highlight
  the changes to the TCP stack, mainly:
    - when the bpf prog will be called in the TCP stack and
    - what information needs to pump through the TCP stack to the actual bpf
      prog callsite.

  The bpf_skops_* functions will be fully implemented in patch 9 together
  with other bpf pieces.

- Use struct_size() in patch 1 (Eric)

- Add saw_unknown to struct tcp_options_received in patch 4 (Eric)

v3:
- Add kdoc for tcp_make_synack (Jakub Kicinski)
- Add BPF_WRITE_HDR_TCP_CURRENT_MSS and BPF_WRITE_HDR_TCP_SYNACK_COOKIE
  in bpf.h to give a clearer meaning to sock_ops->args[0] when
  writing header option.
- Rename BPF_SOCK_OPS_PARSE_UNKWN_HDR_OPT_CB_FLAG
  to     BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG

v2:
- Instead of limiting the bpf prog to write experimental
  option (kind:254, magic:0xeB9F), this revision allows the bpf prog to
  write any TCP header option through the bpf_store_hdr_opt() helper.
  That will allow different bpf-progs to write its own
  option and the helper will guarantee there is no duplication.

- Add bpf_load_hdr_opt() helper to search a particular option by kind.
  Some of the get_syn logic is refactored to bpf_sock_ops_get_syn().

- Since bpf prog is no longer limited to option (254, 0xeB9F),
  the TCP_SKB_CB(skb)->bpf_hdr_opt_off is no longer needed.
  Instead, when there is any option kernel cannot recognize,
  the bpf prog will be called if the
  BPF_SOCK_OPS_PARSE_UNKWN_HDR_OPT_CB_FLAG is set.
  [ The "unknown_opt" is learned in tcp_parse_options() in patch 4. ]

- Add BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG.
  If this flag is set, the bpf-prog will be called
  on all tcp packet received at an established sk.
  It will be useful to ensure a previously written header option is
  received by the peer.
  e.g. The latter test is using this on the active-side during syncookie.

- The test_tcp_hdr_options.c is adjusted accordingly
  to test writing both experimental and regular TCP header option.

- The test_misc_tcp_hdr_options.c is added to mainly
  test different cases on the new helpers.

- Break up the TCP_BPF_RTO_MIN and TCP_BPF_DELACK_MAX into
  two patches.

- Directly store the tcp_hdrlen in "struct saved_syn" instead of
  going back to the tcp header to obtain it by "th->doff * 4"

- Add a new optval(==2) for setsockopt(TCP_SAVE_SYN) such
  that it will also store the mac header (patch 9).
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      890f4365
    • Martin KaFai Lau's avatar
      tcp: bpf: Optionally store mac header in TCP_SAVE_SYN · 267cf9fa
      Martin KaFai Lau authored 
      This patch is adapted from Eric's patch in an earlier discussion [1].

The TCP_SAVE_SYN currently only stores the network header and
tcp header.  This patch allows it to optionally store
the mac header also if the setsockopt's optval is 2.

It requires one more bit for the "save_syn" bit field in tcp_sock.
This patch achieves this by moving the syn_smc bit next to the is_mptcp.
The syn_smc is currently used with the TCP experimental option.  Since
syn_smc is only used when CONFIG_SMC is enabled, this patch also puts
the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did
with "IS_ENABLED(CONFIG_MPTCP)".

The mac_hdrlen is also stored in the "struct saved_syn"
to allow a quick offset from the bpf prog if it chooses to start
getting from the network header or the tcp header.

[1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/



Suggested-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20200820190123.2886935-1-kafai@fb.com
      267cf9fa
    • Martin KaFai Lau's avatar
      bpf: selftests: Tcp header options · ad2f8eb0
      Martin KaFai Lau authored 
      

This patch adds tests for the new bpf tcp header option feature.

test_tcp_hdr_options.c:
- It tests header option writing and parsing in 3WHS: regular
  connection establishment, fastopen, and syncookie.
- In syncookie, the passive side's bpf prog is asking the active side
  to resend its bpf header option by specifying a RESEND bit in the
  outgoing SYNACK. handle_active_estab() and write_nodata_opt() has
  some details.
- handle_passive_estab() has comments on fastopen.
- It also has test for header writing and parsing in FIN packet.
- Most of the tests is writing an experimental option 254 with magic 0xeB9F.
- The no_exprm_estab() also tests writing a regular TCP option
  without any magic.

test_misc_tcp_options.c:
- It is an one directional test.  Active side writes option and
  passive side parses option.  The focus is to exercise
  the new helpers and API.
- Testing the new helper: bpf_load_hdr_opt() and bpf_store_hdr_opt().
- Testing the bpf_getsockopt(TCP_BPF_SYN).
- Negative tests for the above helpers.
- Testing the sock_ops->skb_data.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190117.2886749-1-kafai@fb.com
      ad2f8eb0
    • Martin KaFai Lau's avatar
      bpf: selftests: Add fastopen_connect to network_helpers · 8085e1dc
      Martin KaFai Lau authored 
      

This patch adds a fastopen_connect() helper which will
be used in a later test.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190111.2886196-1-kafai@fb.com
      8085e1dc
    • Martin KaFai Lau's avatar
      bpf: tcp: Allow bpf prog to write and parse TCP header option · 0813a841
      Martin KaFai Lau authored 
      [ Note: The TCP changes here is mainly to implement the bpf
  pieces into the bpf_skops_*() functions introduced
  in the earlier patches. ]

The earlier effort in BPF-TCP-CC allows the TCP Congestion Control
algorithm to be written in BPF.  It opens up opportunities to allow
a faster turnaround time in testing/releasing new congestion control
ideas to production environment.

The same flexibility can be extended to writing TCP header option.
It is not uncommon that people want to test new TCP header option
to improve the TCP performance.  Another use case is for data-center
that has a more controlled environment and has more flexibility in
putting header options for internal only use.

For example, we want to test the idea in putting maximum delay
ACK in TCP header option which is similar to a draft RFC proposal [1].

This patch introduces the necessary BPF API and use them in the
TCP stack to allow BPF_PROG_TYPE_SOCK_OPS program to parse
and write TCP header options.  It currently supports most of
the TCP packet except RST.

Supported TCP header option:
───────────────────────────
This patch allows the bpf-prog to write any option kind.
Different bpf-progs can write its own option by calling the new helper
bpf_store_hdr_opt().  The helper will ensure there is no duplicated
option in the header.

By allowing bpf-prog to write any option kind, this gives a lot of
flexibility to the bpf-prog.  Different bpf-prog can write its
own option kind.  It could also allow the bpf-prog to support a
recently standardized option on an older kernel.

Sockops Callback Flags:
──────────────────────
The bpf program will only be called to parse/write tcp header option
if the following newly added callback flags are enabled
in tp->bpf_sock_ops_cb_flags:
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG

A few words on the PARSE CB flags.  When the above PARSE CB flags are
turned on, the bpf-prog will be called on packets received
at a sk that has at least reached the ESTABLISHED state.
The parsing of the SYN-SYNACK-ACK will be discussed in the
"3 Way HandShake" section.

The default is off for all of the above new CB flags, i.e. the bpf prog
will not be called to parse or write bpf hdr option.  There are
details comment on these new cb flags in the UAPI bpf.h.

sock_ops->skb_data and bpf_load_hdr_opt()
─────────────────────────────────────────
sock_ops->skb_data and sock_ops->skb_data_end covers the whole
TCP header and its options.  They are read only.

The new bpf_load_hdr_opt() helps to read a particular option "kind"
from the skb_data.

Please refer to the comment in UAPI bpf.h.  It has details
on what skb_data contains under different sock_ops->op.

3 Way HandShake
───────────────
The bpf-prog can learn if it is sending SYN or SYNACK by reading the
sock_ops->skb_tcp_flags.

* Passive side

When writing SYNACK (i.e. sock_ops->op == BPF_SOCK_OPS_WRITE_HDR_OPT_CB),
the received SYN skb will be available to the bpf prog.  The bpf prog can
use the SYN skb (which may carry the header option sent from the remote bpf
prog) to decide what bpf header option should be written to the outgoing
SYNACK skb.  The SYN packet can be obtained by getsockopt(TCP_BPF_SYN*).
More on this later.  Also, the bpf prog can learn if it is in syncookie
mode (by checking sock_ops->args[0] == BPF_WRITE_HDR_TCP_SYNACK_COOKIE).

The bpf prog can store the received SYN pkt by using the existing
bpf_setsockopt(TCP_SAVE_SYN).  The example in a later patch does it.
[ Note that the fullsock here is a listen sk, bpf_sk_storage
  is not very useful here since the listen sk will be shared
  by many concurrent connection requests.

  Extending bpf_sk_storage support to request_sock will add weight
  to the minisock and it is not necessary better than storing the
  whole ~100 bytes SYN pkt. ]

When the connection is established, the bpf prog will be called
in the existing PASSIVE_ESTABLISHED_CB callback.  At that time,
the bpf prog can get the header option from the saved syn and
then apply the needed operation to the newly established socket.
The later patch will use the max delay ack specified in the SYN
header and set the RTO of this newly established connection
as an example.

The received ACK (that concludes the 3WHS) will also be available to
the bpf prog during PASSIVE_ESTABLISHED_CB through the sock_ops->skb_data.
It could be useful in syncookie scenario.  More on this later.

There is an existing getsockopt "TCP_SAVED_SYN" to return the whole
saved syn pkt which includes the IP[46] header and the TCP header.
A few "TCP_BPF_SYN*" getsockopt has been added to allow specifying where to
start getting from, e.g. starting from TCP header, or from IP[46] header.

The new getsockopt(TCP_BPF_SYN*) will also know where it can get
the SYN's packet from:
  - (a) the just received syn (available when the bpf prog is writing SYNACK)
        and it is the only way to get SYN during syncookie mode.
  or
  - (b) the saved syn (available in PASSIVE_ESTABLISHED_CB and also other
        existing CB).

The bpf prog does not need to know where the SYN pkt is coming from.
The getsockopt(TCP_BPF_SYN*) will hide this details.

Similarly, a flags "BPF_LOAD_HDR_OPT_TCP_SYN" is also added to
bpf_load_hdr_opt() to read a particular header option from the SYN packet.

* Fastopen

Fastopen should work the same as the regular non fastopen case.
This is a test in a later patch.

* Syncookie

For syncookie, the later example patch asks the active
side's bpf prog to resend the header options in ACK.  The server
can use bpf_load_hdr_opt() to look at the options in this
received ACK during PASSIVE_ESTABLISHED_CB.

* Active side

The bpf prog will get a chance to write the bpf header option
in the SYN packet during WRITE_HDR_OPT_CB.  The received SYNACK
pkt will also be available to the bpf prog during the existing
ACTIVE_ESTABLISHED_CB callback through the sock_ops->skb_data
and bpf_load_hdr_opt().

* Turn off header CB flags after 3WHS

If the bpf prog does not need to write/parse header options
beyond the 3WHS, the bpf prog can clear the bpf_sock_ops_cb_flags
to avoid being called for header options.
Or the bpf-prog can select to leave the UNKNOWN_HDR_OPT_CB_FLAG on
so that the kernel will only call it when there is option that
the kernel cannot handle.

[1]: draft-wang-tcpm-low-latency-opt-00
     https://tools.ietf.org/html/draft-wang-tcpm-low-latency-opt-00



Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820190104.2885895-1-kafai@fb.com
      0813a841