From: Daniel Borkmann <daniel@iogearbox.net>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
Marek Majkowski <marek@cloudflare.com>,
Lorenz Bauer <lmb@cloudflare.com>,
Alan Maguire <alan.maguire@oracle.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 2/5] bpf: Add support for setting chain call sequence for programs
Date: Mon, 7 Oct 2019 22:38:55 +0200 [thread overview]
Message-ID: <20191007203855.GE27307@pc-66.home> (raw)
In-Reply-To: <157046883723.2092443.3902769602513209987.stgit@alrua-x1>
On Mon, Oct 07, 2019 at 07:20:37PM +0200, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke@redhat.com>
>
> This adds support for setting and deleting bpf chain call programs through
> a couple of new commands in the bpf() syscall. The CHAIN_ADD and CHAIN_DEL
> commands take two eBPF program fds and a return code, and install the
> 'next' program to be chain called after the 'prev' program if that program
> returns 'retcode'. A retcode of -1 means "wildcard", so that the program
> will be executed regardless of the previous program's return code.
>
>
> The syscall command names are based on Alexei's prog_chain example[0],
> which Alan helpfully rebased on current bpf-next. However, the logic and
> program storage is obviously adapted to the execution logic in the previous
> commit.
>
> [0] https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git/commit/?h=prog_chain&id=f54f45d00f91e083f6aec2abe35b6f0be52ae85b&context=15
>
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
> include/uapi/linux/bpf.h | 10 ++++++
> kernel/bpf/syscall.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 88 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 1ce80a227be3..b03c23963af8 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -107,6 +107,9 @@ enum bpf_cmd {
> BPF_MAP_LOOKUP_AND_DELETE_ELEM,
> BPF_MAP_FREEZE,
> BPF_BTF_GET_NEXT_ID,
> + BPF_PROG_CHAIN_ADD,
> + BPF_PROG_CHAIN_DEL,
> + BPF_PROG_CHAIN_GET,
> };
>
> enum bpf_map_type {
> @@ -516,6 +519,13 @@ union bpf_attr {
> __u64 probe_offset; /* output: probe_offset */
> __u64 probe_addr; /* output: probe_addr */
> } task_fd_query;
> +
> + struct { /* anonymous struct used by BPF_PROG_CHAIN_* commands */
> + __u32 prev_prog_fd;
> + __u32 next_prog_fd;
> + __u32 retcode;
> + __u32 next_prog_id; /* output: prog_id */
> + };
> } __attribute__((aligned(8)));
>
> /* The description below is an attempt at providing documentation to eBPF
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index b8a203a05881..be8112e08a88 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2113,6 +2113,79 @@ static int bpf_prog_test_run(const union bpf_attr *attr,
> return ret;
> }
>
> +#define BPF_PROG_CHAIN_LAST_FIELD next_prog_id
> +
> +static int bpf_prog_chain(int cmd, const union bpf_attr *attr,
> + union bpf_attr __user *uattr)
> +{
> + struct bpf_prog *prog, *next_prog, *old_prog;
> + struct bpf_prog **array;
> + int ret = -EOPNOTSUPP;
> + u32 index, prog_id;
> +
> + if (CHECK_ATTR(BPF_PROG_CHAIN))
> + return -EINVAL;
> +
> + /* Index 0 is wildcard, encoded as ~0 by userspace */
> + if (attr->retcode == ((u32) ~0))
> + index = 0;
> + else
> + index = attr->retcode + 1;
> +
> + if (index >= BPF_NUM_CHAIN_SLOTS)
> + return -E2BIG;
> +
> + prog = bpf_prog_get(attr->prev_prog_fd);
> + if (IS_ERR(prog))
> + return PTR_ERR(prog);
> +
> + /* If the chain_calls bit is not set, that's because the chain call flag
> + * was not set on program load, and so we can't support chain calls.
> + */
> + if (!prog->chain_calls)
> + goto out;
> +
> + array = prog->aux->chain_progs;
> +
> + switch (cmd) {
> + case BPF_PROG_CHAIN_ADD:
> + next_prog = bpf_prog_get(attr->next_prog_fd);
> + if (IS_ERR(next_prog)) {
> + ret = PTR_ERR(next_prog);
> + break;
> + }
> + old_prog = xchg(array + index, next_prog);
> + if (old_prog)
> + bpf_prog_put(old_prog);
> + ret = 0;
> + break;
How are circular dependencies resolved here? Seems the situation is
not prevented, so progs unloaded via XDP won't get the __bpf_prog_free()
call where they then drop the references of all the other progs in the
chain.
> + case BPF_PROG_CHAIN_DEL:
> + old_prog = xchg(array + index, NULL);
> + if (old_prog) {
> + bpf_prog_put(old_prog);
> + ret = 0;
> + } else {
> + ret = -ENOENT;
> + }
> + break;
> + case BPF_PROG_CHAIN_GET:
> + old_prog = READ_ONCE(array[index]);
> + if (old_prog) {
> + prog_id = old_prog->aux->id;
> + if (put_user(prog_id, &uattr->next_prog_id))
> + ret = -EFAULT;
> + else
> + ret = 0;
> + } else
> + ret = -ENOENT;
> + break;
> + }
> +
> +out:
> + bpf_prog_put(prog);
> + return ret;
> +}
> +
> #define BPF_OBJ_GET_NEXT_ID_LAST_FIELD next_id
>
> static int bpf_obj_get_next_id(const union bpf_attr *attr,
> @@ -2885,6 +2958,11 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
> case BPF_PROG_TEST_RUN:
> err = bpf_prog_test_run(&attr, uattr);
> break;
> + case BPF_PROG_CHAIN_ADD:
> + case BPF_PROG_CHAIN_DEL:
> + case BPF_PROG_CHAIN_GET:
> + err = bpf_prog_chain(cmd, &attr, uattr);
> + break;
> case BPF_PROG_GET_NEXT_ID:
> err = bpf_obj_get_next_id(&attr, uattr,
> &prog_idr, &prog_idr_lock);
>
next prev parent reply other threads:[~2019-10-07 20:39 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 17:20 [PATCH bpf-next v3 0/5] xdp: Support multiple programs on a single interface through chain calls Toke Høiland-Jørgensen
2019-10-07 17:20 ` [PATCH bpf-next v3 1/5] bpf: Support chain calling multiple BPF programs after each other Toke Høiland-Jørgensen
2019-10-07 20:42 ` Alexei Starovoitov
2019-10-08 8:07 ` Toke Høiland-Jørgensen
2019-10-09 1:51 ` Alexei Starovoitov
2019-10-09 8:03 ` Toke Høiland-Jørgensen
2019-10-10 4:41 ` Alexei Starovoitov
2019-10-14 12:35 ` Toke Høiland-Jørgensen
2019-10-14 17:08 ` John Fastabend
2019-10-14 18:48 ` Toke Høiland-Jørgensen
2019-10-15 16:30 ` Edward Cree
2019-10-15 16:42 ` Toke Høiland-Jørgensen
2019-10-15 18:33 ` Edward Cree
2019-10-17 12:11 ` Toke Høiland-Jørgensen
2019-10-22 17:27 ` Edward Cree
2019-10-22 18:07 ` Toke Høiland-Jørgensen
2019-11-12 2:51 ` static and dynamic linking. Was: [PATCH bpf-next v3 1/5] bpf: Support chain calling multiple BPF Alexei Starovoitov
2019-11-12 16:20 ` Toke Høiland-Jørgensen
2019-11-12 19:52 ` Alexei Starovoitov
2019-11-12 21:25 ` Edward Cree
2019-11-12 23:18 ` Alexei Starovoitov
2019-11-13 18:30 ` Edward Cree
2019-11-13 18:51 ` Andrii Nakryiko
2019-11-15 2:13 ` Alexei Starovoitov
2019-11-15 16:56 ` John Fastabend
2019-11-12 23:25 ` John Fastabend
2019-11-13 0:21 ` Alexei Starovoitov
2019-11-13 5:33 ` John Fastabend
2019-11-15 1:50 ` Alexei Starovoitov
2019-11-15 16:39 ` John Fastabend
2019-11-14 15:41 ` Toke Høiland-Jørgensen
2019-11-12 16:32 ` Edward Cree
2019-11-15 11:48 ` Lorenz Bauer
2019-11-15 23:02 ` Alexei Starovoitov
2019-11-18 13:29 ` Lorenz Bauer
2019-10-21 23:51 ` [PATCH bpf-next v3 1/5] bpf: Support chain calling multiple BPF programs after each other Edward Cree
2019-10-16 2:28 ` Alexei Starovoitov
2019-10-16 8:27 ` Jesper Dangaard Brouer
2019-10-16 10:35 ` Daniel Borkmann
2019-10-16 11:16 ` Toke Høiland-Jørgensen
2019-10-16 13:51 ` Toke Høiland-Jørgensen
2019-10-19 20:09 ` bpf indirect calls Alexei Starovoitov
2019-10-20 10:58 ` Toke Høiland-Jørgensen
2019-10-25 16:30 ` Alexei Starovoitov
2019-10-27 12:15 ` Toke Høiland-Jørgensen
2023-09-27 13:27 ` Matt Bobrowski
2023-09-29 21:06 ` Alexei Starovoitov
2023-10-02 18:50 ` Barret Rhoden
2023-10-06 9:36 ` Matt Bobrowski
2023-10-06 18:49 ` Alexei Starovoitov
2023-10-19 12:28 ` Matt Bobrowski
2019-10-09 10:19 ` [PATCH bpf-next v3 1/5] bpf: Support chain calling multiple BPF programs after each other Jesper Dangaard Brouer
2019-10-09 17:57 ` Alexei Starovoitov
2019-10-07 17:20 ` [PATCH bpf-next v3 2/5] bpf: Add support for setting chain call sequence for programs Toke Høiland-Jørgensen
2019-10-07 20:38 ` Daniel Borkmann [this message]
2019-10-08 8:09 ` Toke Høiland-Jørgensen
2019-10-07 17:20 ` [PATCH bpf-next v3 3/5] tools: Update bpf.h header for program chain calls Toke Høiland-Jørgensen
2019-10-07 17:20 ` [PATCH bpf-next v3 4/5] libbpf: Add syscall wrappers for BPF_PROG_CHAIN_* commands Toke Høiland-Jørgensen
2019-10-07 17:20 ` [PATCH bpf-next v3 5/5] selftests: Add tests for XDP chain calls Toke Høiland-Jørgensen
2019-10-07 18:58 ` [PATCH bpf-next v3 0/5] xdp: Support multiple programs on a single interface through " John Fastabend
2019-10-08 8:42 ` Toke Høiland-Jørgensen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191007203855.GE27307@pc-66.home \
--to=daniel@iogearbox.net \
--cc=alan.maguire@oracle.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=brouer@redhat.com \
--cc=davem@davemloft.net \
--cc=kafai@fb.com \
--cc=lmb@cloudflare.com \
--cc=marek@cloudflare.com \
--cc=netdev@vger.kernel.org \
--cc=songliubraving@fb.com \
--cc=toke@redhat.com \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).