kernel/linux.git/include/net/tcp.h, branch v5.10.7

bpf: tcp: Do not limit cb_flags when creating child sk from listen sk

2020-10-02T18:34:48+00:00

The commit 0813a841566f ("bpf: tcp: Allow bpf prog to write and parse TCP header option") unnecessarily introduced bpf_skops_init_child() which limited the child sk from inheriting all bpf_sock_ops_cb_flags of the listen sk. That breaks existing user expectation. This patch removes the bpf_skops_init_child() and just allows sock_copy() to do its job to copy everything from listen sk to the child sk. Fixes: 0813a841566f ("bpf: tcp: Allow bpf prog to write and parse TCP header option") Reported-by: Stanislav Fomichev Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201002013448.2542025-1-kafai@fb.com

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2020-09-23T20:11:11+00:00

Alexei Starovoitov says: ==================== pull-request: bpf-next 2020-09-23 The following pull-request contains BPF updates for your *net-next* tree. We've added 95 non-merge commits during the last 22 day(s) which contain a total of 124 files changed, 4211 insertions(+), 2040 deletions(-). The main changes are: 1) Full multi function support in libbpf, from Andrii. 2) Refactoring of function argument checks, from Lorenz. 3) Make bpf_tail_call compatible with functions (subprograms), from Maciej. 4) Program metadata support, from YiFei. 5) bpf iterator optimizations, from Yonghong. ==================== Signed-off-by: David S. Miller

mptcp: call tcp_cleanup_rbuf on subflows

2020-09-14T20:28:02+00:00

That is needed to let the subflows announce promptly when new space is available in the receive buffer. tcp_cleanup_rbuf() is currently a static function, drop the scope modifier and add a declaration in the TCP header. Reviewed-by: Mat Martineau Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller

tcp: simplify tcp_set_congestion_control(): Always reinitialize

2020-09-11T03:53:01+00:00

Now that the previous patches ensure that all call sites for tcp_set_congestion_control() want to initialize congestion control, we can simplify tcp_set_congestion_control() by removing the reinit argument and the code to support it. Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: Alexei Starovoitov Acked-by: Yuchung Cheng Acked-by: Kevin Yang Cc: Lawrence Brakmo

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2020-09-01T20:22:59+00:00

Daniel Borkmann says: ==================== pull-request: bpf-next 2020-09-01 The following pull-request contains BPF updates for your *net-next* tree. There are two small conflicts when pulling, resolve as follows: 1) Merge conflict in tools/lib/bpf/libbpf.c between 88a82120282b ("libbpf: Factor out common ELF operations and improve logging") in bpf-next and 1e891e513e16 ("libbpf: Fix map index used in error message") in net-next. Resolve by taking the hunk in bpf-next: [...] scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx); data = elf_sec_data(obj, scn); if (!scn || !data) { pr_warn("elf: failed to get %s map definitions for %s\n", MAPS_ELF_SEC, obj->path); return -EINVAL; } [...] 2) Merge conflict in drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c between 9647c57b11e5 ("xsk: i40e: ice: ixgbe: mlx5: Test for dma_need_sync earlier for better performance") in bpf-next and e20f0dbf204f ("net/mlx5e: RX, Add a prefetch command for small L1_CACHE_BYTES") in net-next. Resolve the two locations by retaining net_prefetch() and taking xsk_buff_dma_sync_for_cpu() from bpf-next. Should look like: [...] xdp_set_data_meta_invalid(xdp); xsk_buff_dma_sync_for_cpu(xdp, rq->xsk_pool); net_prefetch(xdp->data); [...] We've added 133 non-merge commits during the last 14 day(s) which contain a total of 246 files changed, 13832 insertions(+), 3105 deletions(-). The main changes are: 1) Initial support for sleepable BPF programs along with bpf_copy_from_user() helper for tracing to reliably access user memory, from Alexei Starovoitov. 2) Add BPF infra for writing and parsing TCP header options, from Martin KaFai Lau. 3) bpf_d_path() helper for returning full path for given 'struct path', from Jiri Olsa. 4) AF_XDP support for shared umems between devices and queues, from Magnus Karlsson. 5) Initial prep work for full BPF-to-BPF call support in libbpf, from Andrii Nakryiko. 6) Generalize bpf_sk_storage map & add local storage for inodes, from KP Singh. 7) Implement sockmap/hash updates from BPF context, from Lorenz Bauer. 8) BPF xor verification for scalar types & add BPF link iterator, from Yonghong Song. 9) Use target's prog type for BPF_PROG_TYPE_EXT prog verification, from Udip Pant. 10) Rework BPF tracing samples to use libbpf loader, from Daniel T. Lee. 11) Fix xdpsock sample to really cycle through all buffers, from Weqaar Janjua. 12) Improve type safety for tun/veth XDP frame handling, from Maciej Żenczykowski. 13) Various smaller cleanups and improvements all over the place. ==================== Signed-off-by: David S. Miller

net: ipv4: remove unused arg exact_dif in compute_score

2020-08-31T20:08:29+00:00

The arg exact_dif is not used anymore, remove it. inet_exact_dif_match() is no longer needed after the above is removed, so remove it too. Signed-off-by: Miaohe Lin Signed-off-by: David S. Miller

bpf: tcp: Allow bpf prog to write and parse TCP header option

2020-08-24T21:35:00+00:00

[ 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: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200820190104.2885895-1-kafai@fb.com

bpf: tcp: Add bpf_skops_hdr_opt_len() and bpf_skops_write_hdr_opt()

2020-08-24T21:35:00+00:00

The bpf prog needs to parse the SYN header to learn what options have been sent by the peer's bpf-prog before writing its options into SYNACK. This patch adds a "syn_skb" arg to tcp_make_synack() and send_synack(). This syn_skb will eventually be made available (as read-only) to the bpf prog. This will be the only SYN packet available to the bpf prog during syncookie. For other regular cases, the bpf prog can also use the saved_syn. When writing options, the bpf prog will first be called to tell the kernel its required number of bytes. It is done by the new bpf_skops_hdr_opt_len(). The bpf prog will only be called when the new BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG is set in tp->bpf_sock_ops_cb_flags. When the bpf prog returns, the kernel will know how many bytes are needed and then update the "*remaining" arg accordingly. 4 byte alignment will be included in the "*remaining" before this function returns. The 4 byte aligned number of bytes will also be stored into the opts->bpf_opt_len. "bpf_opt_len" is a newly added member to the struct tcp_out_options. Then the new bpf_skops_write_hdr_opt() will call the bpf prog to write the header options. The bpf prog is only called if it has reserved spaces before (opts->bpf_opt_len > 0). The bpf prog is the last one getting a chance to reserve header space and writing the header option. These two functions are half implemented to highlight the changes in TCP stack. The actual codes preparing the bpf running context and invoking the bpf prog will be added in the later patch with other necessary bpf pieces. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/bpf/20200820190052.2885316-1-kafai@fb.com

bpf: tcp: Add bpf_skops_established()

2020-08-24T21:35:00+00:00

In tcp_init_transfer(), it currently calls the bpf prog to give it a chance to handle the just "ESTABLISHED" event (e.g. do setsockopt on the newly established sk). Right now, it is done by calling the general purpose tcp_call_bpf(). In the later patch, it also needs to pass the just-received skb which concludes the 3 way handshake. E.g. the SYNACK received at the active side. The bpf prog can then learn some specific header options written by the peer's bpf-prog and potentially do setsockopt on the newly established sk. Thus, instead of reusing the general purpose tcp_call_bpf(), a new function bpf_skops_established() is added to allow passing the "skb" to the bpf prog. The actual skb passing from bpf_skops_established() to the bpf prog will happen together in a later patch which has the necessary bpf pieces. A "skb" arg is also added to tcp_init_transfer() such that it can then be passed to bpf_skops_established(). Calling the new bpf_skops_established() instead of tcp_call_bpf() should be a noop in this patch. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200820190039.2884750-1-kafai@fb.com

tcp: bpf: Add TCP_BPF_RTO_MIN for bpf_setsockopt

2020-08-24T21:35:00+00:00

This patch adds bpf_setsockopt(TCP_BPF_RTO_MIN) to allow bpf prog to set the min rto of a connection. It could be used together with the earlier patch which has added bpf_setsockopt(TCP_BPF_DELACK_MAX). A later selftest patch will communicate the max delay ack in a bpf tcp header option and then the receiving side can use bpf_setsockopt(TCP_BPF_RTO_MIN) to set a shorter rto. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Eric Dumazet Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20200820190027.2884170-1-kafai@fb.com