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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@google.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2019-04-25 14:37:24 -07:00 committed by Daniel Borkmann
parent 118c8e9ae6
commit 7f0c57fec8
1 changed files with 54 additions and 0 deletions
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54
tools/bpf/bpftool/net.c
View File

@ -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);