From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>
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: [PATCH bpf-next v2 2/5] bpf: Add support for setting chain call sequence for programs
Date: Fri, 04 Oct 2019 19:22:42 +0200 [thread overview]
Message-ID: <157020976257.1824887.7683650534515359703.stgit@alrua-x1> (raw)
In-Reply-To: <157020976030.1824887.7191033447861395957.stgit@alrua-x1>
From: Alan Maguire <alan.maguire@oracle.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 febe8934d19a..b5dbc49fa1a3 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 c2a49df5f921..054b1f7c83f8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2112,6 +2112,79 @@ 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_array *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 no chain_progs array is set, that's because the chain call flag
+ * was not set on program load, and so we can't support chain calls.
+ */
+ if (!prog->aux->chain_progs)
+ 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->ptrs + index, next_prog);
+ if (old_prog)
+ bpf_prog_put(old_prog);
+ ret = 0;
+ break;
+ case BPF_PROG_CHAIN_DEL:
+ old_prog = xchg(array->ptrs + 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->ptrs + 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,
@@ -2884,6 +2957,11 @@ 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:[~2019-10-04 17:22 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 17:22 [PATCH bpf-next v2 0/5] xdp: Support multiple programs on a single interface through chain calls Toke Høiland-Jørgensen
2019-10-04 17:22 ` [PATCH bpf-next v2 1/5] bpf: Support injecting chain calls into BPF programs on load Toke Høiland-Jørgensen
2019-10-04 20:51 ` kbuild test robot
2019-10-04 21:12 ` kbuild test robot
2019-10-04 23:17 ` Jakub Kicinski
2019-10-05 10:29 ` Toke Høiland-Jørgensen
2019-10-06 3:39 ` Jakub Kicinski
2019-10-06 15:52 ` Toke Høiland-Jørgensen
2019-10-05 10:32 ` Toke Høiland-Jørgensen
2019-10-07 0:27 ` Alexei Starovoitov
2019-10-07 10:11 ` Toke Høiland-Jørgensen
2019-10-07 20:22 ` Daniel Borkmann
2019-10-08 9:00 ` Toke Høiland-Jørgensen
2019-10-07 20:45 ` Alexei Starovoitov
2019-10-08 9:02 ` Toke Høiland-Jørgensen
2019-10-04 17:22 ` Toke Høiland-Jørgensen [this message]
2019-10-04 23:18 ` [PATCH bpf-next v2 2/5] bpf: Add support for setting chain call sequence for programs Jakub Kicinski
2019-10-05 10:30 ` Toke Høiland-Jørgensen
2019-10-04 17:22 ` [PATCH bpf-next v2 3/5] tools: Update bpf.h header for program chain calls Toke Høiland-Jørgensen
2019-10-04 17:22 ` [PATCH bpf-next v2 4/5] libbpf: Add syscall wrappers for BPF_PROG_CHAIN_* commands Toke Høiland-Jørgensen
2019-10-04 17:22 ` [PATCH bpf-next v2 5/5] selftests: Add tests for XDP chain calls Toke Høiland-Jørgensen
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