* [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type
@ 2019-04-24 16:09 Stanislav Fomichev
2019-04-24 16:09 ` [PATCH bpf-next v2 2/2] bpftool: show flow_dissector attachment status Stanislav Fomichev
2019-04-24 21:01 ` [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Jann Horn
0 siblings, 2 replies; 4+ messages in thread
From: Stanislav Fomichev @ 2019-04-24 16:09 UTC (permalink / raw)
To: netdev, bpf
Cc: davem, ast, daniel, jakub.kicinski, quentin.monnet, Stanislav Fomichev
target_fd is target namespace. If there is a flow dissector BPF program
attached to that namespace, its (single) id is returned.
v2:
* don't sleep in rcu critical section (Jakub Kicinski)
* check input prog_cnt (exit early)
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
include/linux/skbuff.h | 8 ++++++++
kernel/bpf/syscall.c | 2 ++
net/core/flow_dissector.c | 37 +++++++++++++++++++++++++++++++++++++
3 files changed, 47 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 998256c2820b..9f499c0ac53b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1258,11 +1258,19 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
unsigned int key_count);
#ifdef CONFIG_NET
+int skb_flow_dissector_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr);
int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog);
int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
#else
+static int skb_flow_dissector_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 92c9b8a32b50..b0de49598341 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2009,6 +2009,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
break;
case BPF_LIRC_MODE2:
return lirc_prog_query(attr, uattr);
+ case BPF_FLOW_DISSECTOR:
+ return skb_flow_dissector_prog_query(attr, uattr);
default:
return -EINVAL;
}
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index fac712cee9d5..12b92c7d1eae 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -65,6 +65,43 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
}
EXPORT_SYMBOL(skb_flow_dissector_init);
+int skb_flow_dissector_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
+ u32 prog_id, prog_cnt = 0, flags = 0;
+ struct bpf_prog *attached;
+ struct net *net;
+
+ if (attr->query.query_flags)
+ return -EINVAL;
+
+ net = get_net_ns_by_fd(attr->query.target_fd);
+ if (IS_ERR(net))
+ return PTR_ERR(net);
+
+ rcu_read_lock();
+ attached = rcu_dereference(net->flow_dissector_prog);
+ if (attached) {
+ prog_cnt = 1;
+ prog_id = attached->aux->id;
+ }
+ rcu_read_unlock();
+
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
+ return -EFAULT;
+ if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
+ return -EFAULT;
+
+ if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
+ return 0;
+
+ if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
+ return -EFAULT;
+
+ return 0;
+}
+
int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{
--
2.21.0.593.g511ec345e18-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH bpf-next v2 2/2] bpftool: show flow_dissector attachment status
2019-04-24 16:09 [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Stanislav Fomichev
@ 2019-04-24 16:09 ` Stanislav Fomichev
2019-04-24 21:01 ` [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Jann Horn
1 sibling, 0 replies; 4+ messages in thread
From: Stanislav Fomichev @ 2019-04-24 16:09 UTC (permalink / raw)
To: netdev, bpf
Cc: davem, ast, daniel, jakub.kicinski, quentin.monnet, Stanislav Fomichev
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>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type
2019-04-24 16:09 [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Stanislav Fomichev
2019-04-24 16:09 ` [PATCH bpf-next v2 2/2] bpftool: show flow_dissector attachment status Stanislav Fomichev
@ 2019-04-24 21:01 ` Jann Horn
2019-04-24 21:06 ` Stanislav Fomichev
1 sibling, 1 reply; 4+ messages in thread
From: Jann Horn @ 2019-04-24 21:01 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: Network Development, bpf, David S. Miller, Alexei Starovoitov,
Daniel Borkmann, jakub.kicinski, quentin.monnet
On Wed, Apr 24, 2019 at 6:09 PM Stanislav Fomichev <sdf@google.com> wrote:
> target_fd is target namespace. If there is a flow dissector BPF program
> attached to that namespace, its (single) id is returned.
>
> v2:
> * don't sleep in rcu critical section (Jakub Kicinski)
> * check input prog_cnt (exit early)
>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
[...]
> +int skb_flow_dissector_prog_query(const union bpf_attr *attr,
> + union bpf_attr __user *uattr)
> +{
[...]
> + net = get_net_ns_by_fd(attr->query.target_fd);
> + if (IS_ERR(net))
> + return PTR_ERR(net);
At this point, you're holding a refcounted reference to `net`. It
looks like that reference is never dropped?
> +
> + rcu_read_lock();
> + attached = rcu_dereference(net->flow_dissector_prog);
> + if (attached) {
> + prog_cnt = 1;
> + prog_id = attached->aux->id;
> + }
> + rcu_read_unlock();
> +
> + if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
> + return -EFAULT;
[...]
> +}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type
2019-04-24 21:01 ` [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Jann Horn
@ 2019-04-24 21:06 ` Stanislav Fomichev
0 siblings, 0 replies; 4+ messages in thread
From: Stanislav Fomichev @ 2019-04-24 21:06 UTC (permalink / raw)
To: Jann Horn
Cc: Stanislav Fomichev, Network Development, bpf, David S. Miller,
Alexei Starovoitov, Daniel Borkmann, jakub.kicinski,
quentin.monnet
On 04/24, Jann Horn wrote:
> On Wed, Apr 24, 2019 at 6:09 PM Stanislav Fomichev <sdf@google.com> wrote:
> > target_fd is target namespace. If there is a flow dissector BPF program
> > attached to that namespace, its (single) id is returned.
> >
> > v2:
> > * don't sleep in rcu critical section (Jakub Kicinski)
> > * check input prog_cnt (exit early)
> >
> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> [...]
> > +int skb_flow_dissector_prog_query(const union bpf_attr *attr,
> > + union bpf_attr __user *uattr)
> > +{
> [...]
> > + net = get_net_ns_by_fd(attr->query.target_fd);
> > + if (IS_ERR(net))
> > + return PTR_ERR(net);
>
> At this point, you're holding a refcounted reference to `net`. It
> looks like that reference is never dropped?
Ah, indeed, put_net is missing, thanks!
> > +
> > + rcu_read_lock();
> > + attached = rcu_dereference(net->flow_dissector_prog);
> > + if (attached) {
> > + prog_cnt = 1;
> > + prog_id = attached->aux->id;
> > + }
> > + rcu_read_unlock();
> > +
> > + if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
> > + return -EFAULT;
> [...]
> > +}
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-04-24 16:09 [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Stanislav Fomichev
2019-04-24 16:09 ` [PATCH bpf-next v2 2/2] bpftool: show flow_dissector attachment status Stanislav Fomichev
2019-04-24 21:01 ` [PATCH bpf-next v2 1/2] bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type Jann Horn
2019-04-24 21:06 ` Stanislav Fomichev
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