Re: [PATCH bpf-next v1 2/2] selftests: bpf: read netns from struct bpf_sock_ops

From: Song Liu
Date: Tue Apr 16 2019 - 17:51:00 EST

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On Tue, Apr 16, 2019 at 2:07 AM Alban Crequy <alban@xxxxxxxxxx> wrote:
>
> On Fri, Apr 12, 2019 at 8:21 PM Song Liu <liu.song.a23@xxxxxxxxx> wrote:
> >
> > On Fri, Apr 12, 2019 at 3:02 AM Alban Crequy <alban.crequy@xxxxxxxxx> wrote:
> > >
> > > From: Alban Crequy <alban@xxxxxxxxxx>
> > >
> > > This shows how a sockops program could be restricted to a specific
> > > network namespace. The sockops program looks at the current netns via
> > > (struct bpf_sock_ops)->netns and checks if the value matches the
> > > configuration in the new BPF map "sock_netns".
> > >
> > > The test program ./test_sockmap accepts a new parameter "--netns"; the
> > > default value is the current netns found by stat() on /proc/self/ns/net,
> > > so the previous tests still pass:
> > >
> > > sudo ./test_sockmap
> > > ...
> > > Summary: 412 PASSED 0 FAILED
> > > ...
> > > Summary: 824 PASSED 0 FAILED
> > >
> > > I run my additional test in the following way:
> > >
> > > NETNS=$(readlink /proc/self/ns/net | sed 's/^net:\[$.*$\]$/\1/')
> > > CGR=/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-5.scope/
> > > sudo ./test_sockmap --cgroup $CGR --netns $NETNS &
> > >
> > > cat /sys/kernel/debug/tracing/trace_pipe
> > >
> > > echo foo | nc -l 127.0.0.1 8080 &
> > > echo bar | nc 127.0.0.1 8080
> > >
> > > => the connection goes through the sockmap
> > >
> > > When testing with a wrong $NETNS, I get the trace_pipe log:
> > > > not binding connection on netns 4026531992
> > >
> > > Signed-off-by: Alban Crequy <alban@xxxxxxxxxx>
> >
> > Acked-by: Song Liu <songliubraving@xxxxxx>
> >
> > I think we should also add verifier tests for this?
>
> Ok. In tools/testing/selftests/bpf/verifier/var_off.c I could add a
> test with expected result = ACCEPT that reads the 'netns' field.

That sounds good.

Thanks,
Song

>
> Were you thinking of something else or would that be enough?
>
> Thanks,
> Alban
>
>
> > Thanks,
> > Song
> >
> > > ---
> > > tools/include/uapi/linux/bpf.h | 1 +
> > > tools/testing/selftests/bpf/test_sockmap.c | 38 +++++++++++++++++--
> > > .../testing/selftests/bpf/test_sockmap_kern.h | 19 ++++++++++
> > > 3 files changed, 55 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > > index 31a27dd337dc..5afaab25f205 100644
> > > --- a/tools/include/uapi/linux/bpf.h
> > > +++ b/tools/include/uapi/linux/bpf.h
> > > @@ -3069,6 +3069,7 @@ struct bpf_sock_ops {
> > > __u32 sk_txhash;
> > > __u64 bytes_received;
> > > __u64 bytes_acked;
> > > + __u64 netns;
> > > };
> > >
> > > /* Definitions for bpf_sock_ops_cb_flags */
> > > diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
> > > index 3845144e2c91..5a1b9c96fca1 100644
> > > --- a/tools/testing/selftests/bpf/test_sockmap.c
> > > +++ b/tools/testing/selftests/bpf/test_sockmap.c
> > > @@ -2,6 +2,7 @@
> > > // Copyright (c) 2017-2018 Covalent IO, Inc. http://covalent.io
> > > #include <stdio.h>
> > > #include <stdlib.h>
> > > +#include <stdint.h>
> > > #include <sys/socket.h>
> > > #include <sys/ioctl.h>
> > > #include <sys/select.h>
> > > @@ -21,6 +22,7 @@
> > > #include <sys/resource.h>
> > > #include <sys/types.h>
> > > #include <sys/sendfile.h>
> > > +#include <sys/stat.h>
> > >
> > > #include <linux/netlink.h>
> > > #include <linux/socket.h>
> > > @@ -63,8 +65,8 @@ int s1, s2, c1, c2, p1, p2;
> > > int test_cnt;
> > > int passed;
> > > int failed;
> > > -int map_fd[8];
> > > -struct bpf_map *maps[8];
> > > +int map_fd[9];
> > > +struct bpf_map *maps[9];
> > > int prog_fd[11];
> > >
> > > int txmsg_pass;
> > > @@ -84,6 +86,7 @@ int txmsg_ingress;
> > > int txmsg_skb;
> > > int ktls;
> > > int peek_flag;
> > > +uint64_t netns_opt;
> > >
> > > static const struct option long_options[] = {
> > > {"help", no_argument, NULL, 'h' },
> > > @@ -111,6 +114,7 @@ static const struct option long_options[] = {
> > > {"txmsg_skb", no_argument, &txmsg_skb, 1 },
> > > {"ktls", no_argument, &ktls, 1 },
> > > {"peek", no_argument, &peek_flag, 1 },
> > > + {"netns", required_argument, NULL, 'n'},
> > > {0, 0, NULL, 0 }
> > > };
> > >
> > > @@ -1585,6 +1589,7 @@ char *map_names[] = {
> > > "sock_bytes",
> > > "sock_redir_flags",
> > > "sock_skb_opts",
> > > + "sock_netns",
> > > };
> > >
> > > int prog_attach_type[] = {
> > > @@ -1619,6 +1624,8 @@ static int populate_progs(char *bpf_file)
> > > struct bpf_object *obj;
> > > int i = 0;
> > > long err;
> > > + struct stat netns_sb;
> > > + uint64_t netns_ino;
> > >
> > > obj = bpf_object__open(bpf_file);
> > > err = libbpf_get_error(obj);
> > > @@ -1655,6 +1662,28 @@ static int populate_progs(char *bpf_file)
> > > }
> > > }
> > >
> > > + if (netns_opt == 0) {
> > > + err = stat("/proc/self/ns/net", &netns_sb);
> > > + if (err) {
> > > + fprintf(stderr,
> > > + "ERROR: cannot stat network namespace: %ld (%s)\n",
> > > + err, strerror(errno));
> > > + return -1;
> > > + }
> > > + netns_ino = netns_sb.st_ino;
> > > + } else {
> > > + netns_ino = netns_opt;
> > > + }
> > > + i = 1;
> > > + err = bpf_map_update_elem(map_fd[8], &netns_ino, &i, BPF_ANY);
> > > + if (err) {
> > > + fprintf(stderr,
> > > + "ERROR: bpf_map_update_elem (netns): %ld (%s)\n",
> > > + err, strerror(errno));
> > > + return -1;
> > > + }
> > > +
> > > +
> > > return 0;
> > > }
> > >
> > > @@ -1738,7 +1767,7 @@ int main(int argc, char **argv)
> > > if (argc < 2)
> > > return test_suite(-1);
> > >
> > > - while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:p:q:",
> > > + while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:p:q:n:",
> > > long_options, &longindex)) != -1) {
> > > switch (opt) {
> > > case 's':
> > > @@ -1805,6 +1834,9 @@ int main(int argc, char **argv)
> > > return -1;
> > > }
> > > break;
> > > + case 'n':
> > > + netns_opt = strtoull(optarg, NULL, 10);
> > > + break;
> > > case 0:
> > > break;
> > > case 'h':
> > > diff --git a/tools/testing/selftests/bpf/test_sockmap_kern.h b/tools/testing/selftests/bpf/test_sockmap_kern.h
> > > index e7639f66a941..3bad9c70376b 100644
> > > --- a/tools/testing/selftests/bpf/test_sockmap_kern.h
> > > +++ b/tools/testing/selftests/bpf/test_sockmap_kern.h
> > > @@ -91,6 +91,13 @@ struct bpf_map_def SEC("maps") sock_skb_opts = {
> > > .max_entries = 1
> > > };
> > >
> > > +struct bpf_map_def SEC("maps") sock_netns = {
> > > + .type = BPF_MAP_TYPE_HASH,
> > > + .key_size = sizeof(__u64),
> > > + .value_size = sizeof(int),
> > > + .max_entries = 16
> > > +};
> > > +
> > > SEC("sk_skb1")
> > > int bpf_prog1(struct __sk_buff *skb)
> > > {
> > > @@ -132,9 +139,21 @@ int bpf_sockmap(struct bpf_sock_ops *skops)
> > > {
> > > __u32 lport, rport;
> > > int op, err = 0, index, key, ret;
> > > + int i = 0;
> > > + __u64 netns;
> > > + int *allowed;
> > >
> > >
> > > op = (int) skops->op;
> > > + netns = skops->netns;
> > > + bpf_printk("bpf_sockmap: netns = %lu\n", netns);
> > > +
> > > + // Only allow sockmap connection on the configured network namespace
> > > + allowed = bpf_map_lookup_elem(&sock_netns, &netns);
> > > + if (allowed == NULL || *allowed == 0) {
> > > + bpf_printk("not binding connection on netns %lu\n", netns);
> > > + return 0;
> > > + }
> > >
> > > switch (op) {
> > > case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
> > > --
> > > 2.20.1
> > >

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Previous message: Sven Van Asbroeck: "Re: [PATCH v10 0/7] Add Fieldbus subsystem + support HMS Profinet card"
In reply to: Alban Crequy: "Re: [PATCH bpf-next v1 2/2] selftests: bpf: read netns from struct bpf_sock_ops"
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