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Date: Wed, 24 Apr 2019 14:31:41 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
jakub.kicinski@...ronome.com, quentin.monnet@...ronome.com,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v4 2/2] bpftool: show flow_dissector attachment status
Right now there is no way to query whether BPF flow_dissector program
is attached to a network namespace or not. In previous commit, I added
support for querying that info, show it when doing `bpftool net`:
$ bpftool prog loadall ./bpf_flow.o \
/sys/fs/bpf/flow type flow_dissector \
pinmaps /sys/fs/bpf/flow
$ bpftool prog
3: flow_dissector name _dissect tag 8c9e917b513dd5cc gpl
loaded_at 2019-04-23T16:14:48-0700 uid 0
xlated 656B jited 461B memlock 4096B map_ids 1,2
btf_id 1
...
$ bpftool net -j
[{"xdp":[],"tc":[],"flow_dissector":[]}]
$ bpftool prog attach pinned \
/sys/fs/bpf/flow/flow_dissector flow_dissector
$ bpftool net -j
[{"xdp":[],"tc":[],"flow_dissector":["id":3]}]
Doesn't show up in a different net namespace:
$ ip netns add test
$ ip netns exec test bpftool net -j
[{"xdp":[],"tc":[],"flow_dissector":[]}]
Non-json output:
$ bpftool net
xdp:
tc:
flow_dissector:
id 3
v2:
* initialization order (Jakub Kicinski)
* clear errno for batch mode (Quentin Monnet)
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
tools/bpf/bpftool/net.c | 54 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index db0e7de49d49..67e99c56bc88 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -3,6 +3,7 @@
#define _GNU_SOURCE
#include <errno.h>
+#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
@@ -12,6 +13,8 @@
#include <linux/rtnetlink.h>
#include <linux/tc_act/tc_bpf.h>
#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
#include <bpf.h>
#include <nlattr.h>
@@ -48,6 +51,10 @@ struct bpf_filter_t {
int ifindex;
};
+struct bpf_attach_info {
+ __u32 flow_dissector_id;
+};
+
static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
{
struct bpf_netdev_t *netinfo = cookie;
@@ -180,8 +187,45 @@ static int show_dev_tc_bpf(int sock, unsigned int nl_pid,
return 0;
}
+static int query_flow_dissector(struct bpf_attach_info *attach_info)
+{
+ __u32 attach_flags;
+ __u32 prog_ids[1];
+ __u32 prog_cnt;
+ int err;
+ int fd;
+
+ fd = open("/proc/self/ns/net", O_RDONLY);
+ if (fd < 0) {
+ p_err("can't open /proc/self/ns/net: %d",
+ strerror(errno));
+ return -1;
+ }
+ prog_cnt = ARRAY_SIZE(prog_ids);
+ err = bpf_prog_query(fd, BPF_FLOW_DISSECTOR, 0,
+ &attach_flags, prog_ids, &prog_cnt);
+ close(fd);
+ if (err) {
+ if (errno == EINVAL) {
+ /* Older kernel's don't support querying
+ * flow dissector programs.
+ */
+ errno = 0;
+ return 0;
+ }
+ p_err("can't query prog: %s", strerror(errno));
+ return -1;
+ }
+
+ if (prog_cnt == 1)
+ attach_info->flow_dissector_id = prog_ids[0];
+
+ return 0;
+}
+
static int do_show(int argc, char **argv)
{
+ struct bpf_attach_info attach_info = {};
int i, sock, ret, filter_idx = -1;
struct bpf_netdev_t dev_array;
unsigned int nl_pid;
@@ -199,6 +243,10 @@ static int do_show(int argc, char **argv)
usage();
}
+ ret = query_flow_dissector(&attach_info);
+ if (ret)
+ return -1;
+
sock = libbpf_netlink_open(&nl_pid);
if (sock < 0) {
fprintf(stderr, "failed to open netlink sock\n");
@@ -227,6 +275,12 @@ static int do_show(int argc, char **argv)
}
NET_END_ARRAY("\n");
}
+
+ NET_START_ARRAY("flow_dissector", "%s:\n");
+ if (attach_info.flow_dissector_id > 0)
+ NET_DUMP_UINT("id", "id %u", attach_info.flow_dissector_id);
+ NET_END_ARRAY("\n");
+
NET_END_OBJECT;
if (json_output)
jsonw_end_array(json_wtr);
--
2.21.0.593.g511ec345e18-goog
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